Is String Theory A Waste Of Time?

[Juan R.]

Jaun: String theory is a waste of time.

I dissagree. I don't know if string theory is correct or not, and I really don't care. But, even if it is completely wrong, basically no theory is a waste of time, as long as it is well developed and researched. A lot of times, the journey is more important than the goal, I think. All these extremely intelligent people are sitting around pondering string theory. Now imagine if one realized that it was complete BS. If they did, they would have a reason why, and therefore they have created a new theory. So, it isn't a waste of time, even if it is completely wrong, because it prompts debate and refining of the theory. Just think--pretty much all of Aristotles theorys were completely wrong, but people heard about his theorys, and thought that it couldn't be right, and created theorys of their own, which were better and more refined. Generally in physics, you have to be wrong before you can be right.

--Demodocus

But hey, what do I know?


"But, even if it is completely wrong, basically no theory is a waste of time, as long as it is well developed and researched."

The problem is that it is not well developed and researched. As said by Nobel laureate P. Anderson this year, string theory is a futile exercise as physics.

"A lot of times, the journey is more important than the goal, I think."

Well, perhaps, but anybody agree that Einstein unified field theory was a waste of time. He simply ignored experimental data on favour of a "beatiful" idea and he failed. As often ask Nobel laureate Glasgow, why Einstein few years enedeavor is seen like a failure but 30 years-1000 physicists research in string theory do not?

"All these extremely intelligent people are sitting around pondering string theory."

Yes this is another of myths of string theory propaganda. "String theorists are very smart, rest of people is stupid." Still, and this is a really interesting point, no one string theorists have solved or provided solution to some of most difficult open problems of physics, and some of proposed solutions by them are simply stupid. For example, Brian Greene ideas on quantum-classical correspondence were ridiculized last year by Dyson (Nobel laureate).

I think that your emphasis on theories that are still in a initial stage or still nobody know if are both correct or wrong. However, people is critizing string theory because is wrong.

[Igor_S]

However, people is critizing string theory because is wrong.

I'm not a string theorist (nor I plan to be :) ), but can you explain why do you think string theory is wrong ? I thought there are no experimental evidance that go either in favor or against strings and that we should wait until the first results of LHC.

[Demodocus]

Imagine this--

It is the days before newton. One semi-retarded man writes an elaborate paper saying everything falls up. Another man, named Newton, reads this paper, and says.

"What a retard! Things fall down!"

So, Newton writes a paper, which says-

"No, I have never seen anything ever fall up. In fact, things fall down, except for ballons. Ballons are weird. So, things fall down. Mostly."

Everyone doesn't believe this, cause it well, sounds stupid, and not thought out. And also, it has one itsy-bitsy exception.

So, for a while, the world believes everything falls up, because the theory is so elegant and refined.

Newton is pissed off. He spends months testing his theory, while everyone is calling him a idiot. He drops lead balls. He drops ping-pong balls. Soon, he has created a brilliant set of laws defining things falling down. He calls them gravity.



Now, imagine if that first man had not written his paper on things falling up. Newton wouldn't of had to prove him wrong, with good evidence. And, the laws of gravity would of not been found. People would of just accepted the fact that things generally fall down, without really understanding why. A great loss to science.

[Chronos]

String theory is vulnerable, but the concept is sound. I agree it is losing ground, but handwaving objections are objectionable. Don't take that as meaning you are wrong, I just think the right thing to do is to substantiate all objections. You may not arrive at the same conclusion if you think it through. ST is not as weak as it sometimes appears. I have reread Witten's papers a dozen times by now, and he has some very good points. I can't refute them. My gut feeling is ST is wrong, but I have no right to object without a substantive reason.

[Juan R.]

I'm not a string theorist (nor I plan to be :) ), but can you explain why do you think string theory is wrong ? I thought there are no experimental evidance that go either in favor or against strings and that we should wait until the first results of LHC.

First i am not claiming that some parts of string theory can be useful in strong force for example. I was claiming that string theory is wrong like a TOE.

Remember that string theory is, in the words of its more popular practitioners, the Final Theory: the Last True.

The list of obious failures and experimental incorrections of string theory is so imppresive that one needs more than 100 pages for detailing all the math. A small, non-technical o:), criticism is available at www.canonicalscience.com/stringcriticism.pdf.

The idea string theory has been no tested is wrong. String theory has been always tested and always has failed :yuck: . It was tested in the strong force regime 30 years ago and continue to be tested now. For example, some years ago they claimed a cosmological brane model explaining universe. In a tour of force, Andrei Linde (the same of inflationary theory) showed that the model was wrong and the claimed "explainings" do not fit known experimental data.

String theory is wrong; it has failed for explaining everything. It has failed for quantize gravity (perturbative series is not well defined and nonperturbative regime is unknown), it cannot explain GR (contrary to popular Witten claims string theory does not predict gravity, really string theory is adapted to previously known gravity), etc.

String, stwing, M-theory, and all that stuff are a waste of time. Since that their research is based in irrelevant mathematical formalisms and outdated concepts :zzz: . String M-theorists (here and thereafter SMt) are so arrogant that with a superfitial mathematical knowledge of other fields of science, they claim for a Theory Of Everything. The list of outdated concepts and irrelevant mathematical formalisms is greater than number of estimated vacua (-:

- Usual quantization of the classical bosonic string violates cosmological boundaries. (I wait that SMts will recognize this error before 2050 :-).

- The spacetime used (CY, G2, etc.) do not account for the non-differential character of stochastic processes. It will be funny like string theorists will attempt to model spacetime-foam noisy contributions to a triple D0-brane collision. I wait to see their faces then!

- In the usual unitary vectors space of string mathematics the L-product of two elements is not defined. Only in the L-space the relation I+(rs)I+(tu) = I+(ru)delta(st) is defined. No similar product relation exists in the H-space (dimension n) because L-space (dimension nn) is more general. That is, the supposed TOE cannot explain, for instance, Ernst’s work in NMR (that received the Nobel prize) :-)

- The fixed background S-matrix is, undoubtedly, a funny caricature of real-word processes. There are dozens of well-known papers on the topic and even a new branch of string theory developed!

- Vector states used in the standard spectral decomposition of strings (branes) are of course valid only in the limit T --> 0. This was known for decades in other fields of science like plasma physics (quark-gluon plasma). Only the last 5 years, after of three decades of totally wrong research and funny claims, SMts fixed this sound error and developed the very recent Dp-branes theory with the (~) operators, which only work in the linear regime. Far from eq. one cannot use the tilde (~) operators due to well-known presence of dynamical bubbles coupling spacetime events. Of course, all this advanced mathematical stuff was/is ignored by leading researchers like Witten, Greene, Vafa, Schwartz, etc. Witten, the great genius, the great theoretician, the new "Einstein", did NONE contribution to recent doubled space Dp-branes theory. In fact, his great mind did not know the problem with the use of standard states because he like other string theorists study the topics just superficially. He is a great string theorist sure :-)

- String theorists still claim for the derivation of an unitary theory, whereas people in other experimentally proved theories are working with LPS theory in Gelfand triplets. The theorems used are outside of the simple and outdated string mathematics, and one needs a lot of recent mathematical work in rigged spaces and involutive Banach algebra of bounded operators. These non C*-algebras are, of course, ignored by SMTs and their irrelevant TOE. It is impossible to explain recent models for neutral Kaons and its counterparts in higher-flavor-generations from the basic mathematical framework of string, M theory. Concretely the models developed in the last decade by Sudarshan (e.g. generalizing the LOY model) does not fit to string M-theory because are more general.

- Non-critical string theory is more advanced that usual critical (Witten-Schwartz-Vafa-Greene-etc.) one in fixed backgrounds but again irrelevant for a TOE. The most advanced formulation today in non-critical theory simply use “Lindblad–like” operators (which is only valid if one take the zero limit of the correlation functions for the different vacua) to take into account quantum transitions between different critical string vacua. Moreover, the non-critical string theory has unsolved problems. One can show (with the aid of mathematical methods unknown for SMts and still don't applied to noncritical formulation) that non-critical string theory formulation is just a shadow to more consistent and generalized theories.

- Etc, etc, etc, etc, etc.

M-theory is "the best candidate for a theory of everything", sound like that old claim of "all universe is understood from Newton mechanics".

All of us know how accurate was the claim :biggrin:

[Juan R.]

Regardless of the theories merits themselves, I hope we can all agree that the way string theory has been dissiminated to the public is appaling.

Many string theorists are very arrogant. If your theory permits to you compute nothing you would say this to people. It appears that they want emulate to Einstein ant become smart. But sincerely, no one string theorist has done nothing interesting in physics (in other fields like biology, chemistry or non-linear economoy the contribution of string theorists is easily summarized none). Gross won the Nobel Prize for his work on particle physics and Witten was awarded by his mathematical work. No one string theorist has solved some of most important open problems of theoretical physics: quantum measuring, arrow of time, chaos, quantum gravity, unification, etc.

As claimed by particle physicist Peter Woit, the only success of string theory has been in mass media. Many people, undergraduate students, other scientists, etc. are very confused with REAL status of string theory.

For example, in his "popular" Elegant Universe Brian Greene claim that one can explain why there is three spatial extended dimensions from string theory. Why are there 3 instead of 5 or more? Greene explains to his inexpert public that was explained by string theoris (Vafa and others).

Compare that with recent Witten reply to question:

NOVA: If these extra dimensions exist, does string theory offer any explanation of why there are apparently three space dimensions larger than the rest?

Witten: That's a big problem that has to be explained. As of now, string theorists have no explanation of why there are three large dimensions as well as time, and the other dimensions are microscopic. Proposals about that have been all over the map.

There are dozens of other examples of obvious manipulation of true.

**************************************
Is all this lot of false claims, mass media and students manipulation, outdated mathematical research, incorrect hyphotesis, ambiguity (there is no string theory just a program called string theory), incompatibility (some papers claim contrary of others), false propaganda (only 1000 physicists follow this theory and most of smart people and Nobel laureates do not like it) the current fad in theoretical physics?

[Berislav]

The idea string theory has been no tested is wrong. String theory has been always tested and always has failed . It was tested in the strong force regime 30 years ago and continue to be tested now. String theory proved succesful in that respect - the relation of the scattering amplitudes of resonance states of baryons and mesons to the Regge trajectories.

For example, some years ago they claimed a cosmological brane model explaining universe. In a tour of force, Andrei Linde (the same of inflationary theory) showed that the model was wrong and the claimed "explainings" do not fit known experimental data. The brane model you are refering to is a rather crude one, if I'm not mistaken. There have been significant improvements in that regard, particulary pertaining to the use of anti-de Sitter space coupled with conformal field theory. See for instance:
http://arxiv.org/abs/hep-th/0004056
http://ej.iop.org/links/q56/+Z5PIFb0wJ11K+QyiuY82g/jhep062002026.pdf

It has failed for quantize gravity (perturbative series is not well defined and nonperturbative regime is unknown), It's true that there's no non-pertubative string theory.

it cannot explain GR (contrary to popular Witten claims string theory does not predict gravity, really string theory is adapted to previously known gravity), etc. Doesn't massless spin-2 field work?

- Usual quantization of the classical bosonic string violates cosmological boundaries. (I wait that SMts will recognize this error before 2050 :-). How can quantization of strings violate cosmology? Note: A simple method of quantization (which I know of) is to start with a classical string then impose the quantum light-cone gauge and use the Virasoro algebra.

- The spacetime used (CY, G2, etc.) do not account for the non-differential character of stochastic processes. What's non-differential?

[Hurkyl]

It's false that research into String Theory hasn't produced any results in other fields: not only has it generated a wealth of new mathematical ideas, but these theoretical physicists seem to have a knack for solving tough problems in classical mathematics, number theory in particular.

[Hurkyl]

It seems to me that people are criticizing string theory essentially on the basis that it's work in progress, rather than a finished product.

That's a rather absurd way of looking at things. When you have an idea, the corresponding full-fledged theory doesn't appear out of thin air, ripe for testing.

[Juan R.]

String theory proved succesful in that respect - the relation of the scattering amplitudes of resonance states of baryons and mesons to the Regge trajectories.

False!!! The history of physics is there!!! The development of a string theory of ALL aspects of hadrons failed, and the theory was abandoned in favor of the, then new, QCD developed by Gell-Mann. This early failure of string theory is recognized even by string fanatics as Schwartz, who said


Be that as it may, the attempts to construct a string theory of hadrons were not fully successful.


The brane model you are refering to is a rather crude one, if I'm not mistaken. There have been significant improvements in that regard, particulary pertaining to the use of anti-de Sitter space coupled with conformal field theory. See for instance:
http://arxiv.org/abs/hep-th/0004056
http://ej.iop.org/links/q56/+Z5PIFb...ep062002026.pdf

I was referring to J. Khoury, B. A. Ovrut, P. J. Steinhardt and N. Turok. Phys. Rev. D 64, 123522 (2001), what is more modern that your ArXiv link. Lindé did not comment on the paper because was “rude” or “few detailed” still. Simply the computations were completely wrong (even if string theory was correct!!!) and, moreover, the authors introduced lots of assumptions and hidden hypothesis. Moreover in future works, string theorists (arrogant as they are) ignore all failures. Lindé says


The original version of the ekpyrotic scenario contained many incorrect and unproven statements. In particular, instead of expansion of the colliding branes described in [article], one has contraction to a singularity. Despite the optimistic statements of the authors, the singularity problem in this scenario remains unsolved. The theory of density perturbations in this scenario is controversial; most authors believe that the mechanism of generation of density perturbations proposed does not lead to adiabatic perturbations with a at spectrum. Most importantly, this scenario offers no solution to major cosmological problems such as the homogeneity, flatness and entropy problems.

In fact, the homogeneity problem in this scenario is even much more complicated than in the usual non-inflationary big bang theory.

and add


its authors recently issued a paper advertising this scenario in the popular
press and another one aimed at astrophysicists. These new papers, which were supposed to give a summary of the state of the cyclic universe theory, omitted any mention of the criticisms of the scenario. It was claimed in that the cyclic scenario is able to reproduce all of the successful predictions of the consensus model (i.e. of inflationary cosmology -A.L.) with the same exquisite detail.

Of course, Lindé like many of others experts disagree with last above claim. String theory does not work and when it is showed that does not work string theorist ignore the criticism and sent notes to mass media. This make part of string community sociology.

Linde expresses our belief in a brilliant form


I really mean it. I think that we should be very grateful to its authors. Indeed, if a model speculating about an infinite number of singularities is the best alternative to inflation invented during the last 20 years, this means that inflationary theory is in a very good shape.

Cosmologists Kraus called string theory a colossal failure and, if I am now wrong, he is writing a book on the topic that will released this year.


Doesn't massless spin-2 field work?

You are following Feynman’s idea too arbitrarily. Let me focus on details. String action works in 10D and “defines” a perturbative expansion in a fixed background. 1) Gravitons has been not detected, in fact, even gravitational waves are not detected still. 2) The perturbative splitting of metric is incompatible with GR; in fact, GR causality is not supported. 3) If GR was unknown, nobody had substituted the fixed metric in the string by a dynamical one. Therefore, one is forcing ST to compatibility with GR, not deriving the latter from ST. 4) compactification to 4D is done by hand and, moreover, required (ad hoc) for compatibility with usual experimental data not predicted by ST. 5) string theory does not explain astronomical spacetime 6) string spacetime does not account cosmological expansion. 7) The practice in string theory is to assume that spacetime quantum field theory describes the large distance physics. First, a macroscopic background spacetime is chosen by hand, arbitrarily, from among the manifold of possibilities. 8) Etc.


How can quantization of strings violate cosmology? Note: A simple method of quantization (which I know of) is to start with a classical string then impose the quantum light-cone gauge and use the Virasoro algebra.

You are very wrong, just like string theorists. What is the wavefunction of universe, if any?


What's non-differential?

Hum, a note for navigators, Polchinski two volumes on string theory is not I call high-level physics. Brian Greene’s research in Calabi-Yaus is not I call sophisticated math.

In a differential manifold R4 (SR), Calabi-Yau (string theory), G2 (M theory), etc.

The space dx is


dx = vdt


with v the velocity. In general, this is an approximation. The most correct formula is

dx = vdt + fdt

with fdt a non-differentiable element. Most of interesting formulas used in many fields (e.g. Ca^{2+} transport in living cells) are empirical (ad hoc). For example, the assumptions of


\langle f(t) \rangle = 0


and


\langle f(t)f(t') \rangle = cte \ \delta (t-t')


used in white chemical noise.

In canonical science (many times more sophisticated and advanced that stupid string theory), all of these standard formulas arise from basic topological properties of omega coefficients and non-differential character of spacetime foam.


I agree the public has been badly served by the PR of string theory; but such is the case with all of theoretical physics.

The public has been led to believe that the Big Bang and Black Holes at the center of galaxies are both certainties.

I agree, but in other cases, the theories are at least partially useful. The Big bang is not perfect but rationalizes lot of data. From string theory, one can predict or compute nothing in rigor. In fact, all popular claims on string theory are simply wrong. There is a joke in Internet that said that now string theory is a theory without strings, but people ignores this!!!


A purpose of string theory and its derivatives is to unite SR GR and QM in such a way that natural phenomena can be explained with a single and/or a few fundamental concepts. String theory, thus, is a small, limited step towards TOE.

Yes, but it has failed in the unification. In fact, ALL string theorists -so excited in the past- now agree that string theory cannot do it and are searching for a new theory that nobody know and is dubbed M theory.


The fundamental theory (TOE) must unify relativity and quantum mechanics and the non-physics disciplines as well.

Fantastic!!! But since string theorists have no idea of nothing complex (many of them still believe in the reductionist approach!!!), their theory is completely outdated. Canonical science is not reductionist, it unifies chemistry with ecology, economy, physics, etc. but still is not a true TOE. The TOE is a myth; it does not exist.

All macro-predictions of string theory (e.g. Black holes, cosmology, dark matter, etc.) are incorrect or very deficient. In cosmological issues, the discrepancy between theory (string th) and experimental data is far for more than 50 orders of magnitude. Yes you are read ok, 50!!


It's false that research into String Theory hasn't produced any results in other fields: not only has it generated a wealth of new mathematical ideas, but these theoretical physicists seem to have a knack for solving tough problems in classical mathematics, number theory in particular.

Nobody said that string theory was not useful in some mathematical issues. Moreover, there is a popular exaggeration that said that modern math is just string theory math, which is simply stupid. The number of mathematicians working in string theory stuff or similar is really small. People working in other fields has also advanced math without working in string M-theory.


It seems to me that people are criticizing string theory essentially on the basis that it's work in progress, rather than a finished product.

Of course than no!! This is a typical string argumentation. The theory is permanently open by them!!

If string theorist claim for a consistent perturbative regime of quantum gravity (e.g. without infinites) then I could say hey nobody has demonstrated absence of infinites at all orders. Then string theorist could claim that theory is open and I agree.

But if a string theorist claim that universe manifold is aCY or a G2 I said that is wrong and that is independelty of open issues regarding both of those manifolds. If string theorist write the wavefunction for a bosonic string I said that that is wrong if he argues that from string theory he can explain all I said that has no idea of nothing, etc.

That is I am not claiming that string M-theory is almost good with some obscure points that would be corrected in a future because the research is still open. I am claiming that ALL of current string M-theory is completely wrong for a TOE (or quasy-TOE).

The problem is that the name string theory has been maintained by marketing purposes. Many people think that string theory now is the same that two or three decades ago, which is completely false. In fact, the history of string theory is a history of succesive failure due that string theorists are unable to achieve a consistent theory.

I find the next quote that will add to me own collection:


But skeptics suggest it's the latest sign of how string theorists, sometimes called "superstringers," try to colorfully camouflage the theory's flaws, like "a 50-year-old woman wearing way too much lipstick," jokes Robert B. Laughlin, a Nobel Prize-winning physicist at Stanford. "People have been changing string theory in wild ways because it has never worked."

[Tom Mattson]

handwaving objections are objectionable.


Indeed! And I've just finished pruning several of those handwaving objections out of this thread. Let us have no more talk of personalities, no more blanket charges of arrogance, and no more empty arguments propped up by quotes from famous people. Let's raise the standard here. Arguments against string theory should address the theory itself, not those who work on it or things that people say about it.

Juan R: I like what you are doing here. You're getting specific. For instance:


- Usual quantization of the classical bosonic string violates cosmological boundaries. (I wait that SMts will recognize this error before 2050 :-).

- The spacetime used (CY, G2, etc.) do not account for the non-differential character of stochastic processes. It will be funny like string theorists will attempt to model spacetime-foam noisy contributions to a triple D0-brane collision. I wait to see their faces then!

- In the usual unitary vectors space of string mathematics the L-product of two elements is not defined. Only in the L-space the relation I+(rs)I+(tu) = I+(ru)delta(st) is defined. No similar product relation exists in the H-space (dimension n) because L-space (dimension nn) is more general. That is, the supposed TOE cannot explain, for instance, Ernst’s work in NMR (that received the Nobel prize) :-)

- The fixed background S-matrix is, undoubtedly, a funny caricature of real-word processes. There are dozens of well-known papers on the topic and even a new branch of string theory developed!

- Vector states used in the standard spectral decomposition of strings (branes) are of course valid only in the limit T --> 0. This was known for decades in other fields of science like plasma physics (quark-gluon plasma). Only the last 5 years, after of three decades of totally wrong research and funny claims, SMts fixed this sound error and developed the very recent Dp-branes theory with the (~) operators, which only work in the linear regime. Far from eq. one cannot use the tilde (~) operators due to well-known presence of dynamical bubbles coupling spacetime events. Of course, all this advanced mathematical stuff was/is ignored by leading researchers like Witten, Greene, Vafa, Schwartz, etc. Witten, the great genius, the great theoretician, the new "Einstein", did NONE contribution to recent doubled space Dp-branes theory. In fact, his great mind did not know the problem with the use of standard states because he like other string theorists study the topics just superficially. He is a great string theorist sure :-)

- String theorists still claim for the derivation of an unitary theory, whereas people in other experimentally proved theories are working with LPS theory in Gelfand triplets. The theorems used are outside of the simple and outdated string mathematics, and one needs a lot of recent mathematical work in rigged spaces and involutive Banach algebra of bounded operators. These non C*-algebras are, of course, ignored by SMTs and their irrelevant TOE. It is impossible to explain recent models for neutral Kaons and its counterparts in higher-flavor-generations from the basic mathematical framework of string, M theory. Concretely the models developed in the last decade by Sudarshan (e.g. generalizing the LOY model) does not fit to string M-theory because are more general.

- Non-critical string theory is more advanced that usual critical (Witten-Schwartz-Vafa-Greene-etc.) one in fixed backgrounds but again irrelevant for a TOE. The most advanced formulation today in non-critical theory simply use “Lindblad–like” operators (which is only valid if one take the zero limit of the correlation functions for the different vacua) to take into account quantum transitions between different critical string vacua. Moreover, the non-critical string theory has unsolved problems. One can show (with the aid of mathematical methods unknown for SMts and still don't applied to noncritical formulation) that non-critical string theory formulation is just a shadow to more consistent and generalized theories.


I'd like to see the discussion follow these leads. How can we know that these points are true? Why would the truth of these points mean that string theory is wrong? Let's see more of that sort of thing, let's keep it dispassionate, and let's keep it specific. Otherwise I am going to shut this thread down.

[Juan R.]

Let us have no more talk of personalities, no more blanket charges of arrogance, and no more empty arguments propped up by quotes from famous people. Let's raise the standard here. Arguments against string theory should address the theory itself, not those who work on it or things that people say about it.


Well, I beleve that this is a forum, and one would open the hand. Of course, one may search strict scientific/mathematical terms in a formal paper, but here i could one day to say that M(atrix) cannot explain a chemical reaction in condensed phase (is mathematically imposible) and, other, i can say that Lubos Motl is a very arrogant guy with no education (I know that his internet style is "you are @#$%t!!").

People doing mocking of string theory community is doing because string theorist are very arrogant. Each day are proposed dozens of theories/hypotesis. The problem is the "macho-arrogant" attitude of string theorists resumed on string theory is great if you are not working in it a) your are not smart or b) you are stupid and cannot see its "elegance". String theorists are manipulating public, young students (how many students began a PhD in string theory and after leave the field when discover that was ugly?), and public.

Moreover, they did (and continue to do it) many dishonest actions against other theories/people. For example, it is well-known that Glashow (Nobel Prize for physics) was forced to abandon the university due to his incisive criticism to string "theory".

Of course, this is just my point.


How can we know that these points are true?

Studying them, as it is normal in science!



Why would the truth of these points mean that string theory is wrong?

This is obvious. E.g. if your TOE cannot explain RMN spectrum of a protein in solution (the relation I+(rs)I+(tu) = I+(ru)delta(st) is not defined for wavefunctions in a Hilbert-Fock space), then your TOE is not complete and people working in other fields is not doing "applied" stuff.

If string theorists like Schwartz are claiming that string theory is unitary and are searching for an unitary evolutor then i may sday that them have no idea of nothing. There are fields of science that are dozens of times more advanced that string theory but string theorists have no idea of notgin and continue working in outdated stuff.

This is not so surprising for me. Still many physicists believe (of course incorrectly) that chemistry was reduced to QM. In fact, Witten said that in a recent interview. Why? because Dirac said it! Whow what argument!!!

Chemists smile of that mith (look some of multiple papers in Foundations of chemistry journal. Murray Gell-Mann (probably the most smart physicists living) has said in the Quark and the Jaguar that, of course, Dirac famous quote was an exageration.

The question of failure of string theory is joined to string theorists. This is a fact. String theorists do a sect otherwise the scandal around string theory is not seen in other fields of quantum gravity: NC, triangulations, geometrodynamics, LQG (except Smolin and some friends), etc.

[Berislav]

False!!! The history of physics is there!!! The development of a string theory of ALL aspects of hadrons failed Some references would be nice. :smile:

I was referring to J. Khoury, B. A. Ovrut, P. J. Steinhardt and N. Turok. Phys. Rev. D 64, 123522 (2001), what is more modern that your ArXiv link. I am not personally subscribed to APS so I can't view the paper at this time. I will read it as soon as I start my undergraduate courses (via my university's subscription).

String action works in 10D and “defines” a perturbative expansion in a fixed background. Actions of string theory work in other forms in dimensions other than 10.

1) Gravitons has been not detected, in fact, even gravitational waves are not detected still. The former can be attributed to lack of technical ability, while the latter is not only a problem that string theory should be concerned about.

2) The perturbative splitting of metric is incompatible with GR; in fact, GR causality is not supported. Since standard string theory is not backround independent and hence not complatible with GR to begin with the point is moot.

4) compactification to 4D is done by hand and, moreover, required (ad hoc) for compatibility with usual experimental data not predicted by ST. T-duality is a very useful mathematical tool. It makes to theories for all intents and purpuses equivalent. If you can show that it is somehow incorrect then that argument would be fatal to string theory.


How can quantization of strings violate cosmology? Note: A simple method of quantization (which I know of) is to start with a classical string then impose the quantum light-cone gauge and use the Virasoro algebra.

You are very wrong, just like string theorists. How can I be wrong? I merely asked a question, not made a statement.

Most of interesting formulas used in many fields (e.g. LaTeX graphic is being generated. Reload this page in a moment. transport in living cells) are empirical (ad hoc). For example, the assumptions of I am not familiar with physical chemistry, so you will have to forgive my ignorance as I will ask for some references.

[Tom Mattson]

Well, I beleve that this is a forum, and one would open the hand.


You believe wrongly. :smile: Physics Forums is not a place to rant and rave about personalities.


Of course, one may search strict scientific/mathematical terms in a formal paper, but here i could one day to say that M(atrix) cannot explain a chemical reaction in condensed phase (is mathematically imposible) and, other, i can say that Lubos Motl is a very arrogant guy with no education (I know that his internet style is "you are @#$%t!!").


Please stick to the former, avoid the latter. What Lubos Motl does elsewhere on the internet has no bearing on our policies. And I can promise you that if he were to do that here, he would be warned about it.

I'm skipping over the next part, because it is exactly the sort of thing I'd like to avoid.


Tom: How can we know that these points are true?

Juan: Studying them, as it is normal in science!


I mean: Where are the references?


Tom: Why would the truth of these points mean that string theory is wrong?

Juan: This is obvious. E.g. if your TOE cannot explain RMN spectrum of a protein in solution (the relation I+(rs)I+(tu) = I+(ru)delta(st) is not defined for wavefunctions in a Hilbert-Fock space), then your TOE is not complete and people working in other fields is not doing "applied" stuff.


OK, let's back it up a step or two. I find it difficult to accept this as a valid criticism. I can see how one might argue that the calculation you describe above is just too complicated to do with a theory as supposedly fundamental as string theory. What would you say to that? Are you saying that it is impossible to do such a calculation with string theory, even in principle? If so, then how do you know that?


If string theorists like Schwartz are claiming that string theory is unitary and are searching for an unitary evolutor then i may sday that them have no idea of nothing. There are fields of science that are dozens of times more advanced that string theory but string theorists have no idea of notgin and continue working in outdated stuff.


Sure you may say it, but what's the reasoning behind your statements?


The question of failure of string theory is joined to string theorists. This is a fact. String theorists do a sect otherwise the scandal around string theory is not seen in other fields of quantum gravity: NC, triangulations, geometrodynamics, LQG (except Smolin and some friends), etc.


I'll say it one more time: This forum is not for the discussing of personalities.

[brunardot]

Imagine this--

It is the days before newton. One semi-retarded man writes an elaborate paper saying everything falls up. Another man, named Newton, reads this paper, and says.

"What a retard! Things fall down!"

So, Newton writes a paper...

The real moral would seem to be: One should be careful who one calls a semi-retard.

Assuming that “falls” implies acceleration; and, by "up," what actually is intended to be connoted was “outward”; it is now known . . . and well accepted, thanks to the Hubble Space Telescope’s confirmations, that massive Cosmic bodies do “fall up.”

Newton was also wrong about inertia. The HST indicates that inertia should be a force (counter to gravity); however, its acceleration and elliptical curvature, at anthropic scale, is too minuscule to observe because of the great distance from which it operates.

Einstein did have the concept of a Cosmological constant right; only, it’s not constant. And, Einstein, also, had the source, and therefore, the direction wrong.

However, as Einstein well knew, such an adjustment to GR was a structural requisite without the Big Bang. Einstein has the excuse that he couldn’t be aware of later counter-intuitive observations. What excuse do today’s theoretical physicists have?

[Juan R.]

Some references would be nice. :smile:

I'm sorry, I have no time for providing you detailed references. I am very busy and have no time for searching now the papers, but most of i say is based in an abundant recopilated literature (physics, biology, ecology, physics, etc.) that i cited in several works, preprints, books, etc.

Check on canonicalscience.com for papers, non-technical documents, and full lists of references in some time. I believe that my articles on CPS are not available due to closing, but there will be available again in the web above.

I believe that you can search by yourself the history of failure of string theory and of string force simply in Google (i do not check this).


Actions of string theory work in other forms in dimensions other than 10.

Yes, i was refering to "correct" (2, 10) scan of supersymmetric version.


The former can be attributed to lack of technical ability, while the latter is
not only a problem that string theory should be concerned about.

Well, perhaps "can be". Some people like Dyson agrees that there is no gravitons after all.


Since standard string theory is not backround independent and hence not complatible with GR to begin with the point is moot.

That contrast a bit with usual exagerated claims from string theorists. It is wel-known that Witten claimed in popular press that string theory predicts GR. In a recent Scientific American, B. Greene lists one of main advantages of ST over LQG the existence of well defined classical limit that is GR.

Therefore, from "string theory unifies QM and GR" you now are broadly admiting that ST is, in fact, incompatible with GR (just as relativist claimed for decades). Well, please explain that to miles of readers of string theory literature or just to editors of popular magazines like New York times or similar.

Moreover, i believe that you ignores that, in the past, string theorists thought that full background invariance of GR was just a macroscopic approximation and initially they really thought that the split was correct. In fact, the perturbation of classical flat metric was interpreted like the real graviton.


T-duality is a very useful mathematical tool. It makes to theories for all intents and purpuses equivalent. If you can show that it is somehow incorrect then that argument would be fatal to string theory.

I was talking about compactification M10 -> R4 x M6.



How can I be wrong? I merely asked a question, not made a statement.

Ok. I believe that you do not know about these issues because you ask on it. I think that you believe that there is a wavefunction for the universe, otherwise you would not ask "How can quantization of strings violate cosmology?".

[Juan R.]

Please stick to the former, avoid the latter. What Lubos Motl does elsewhere on the internet has no bearing on our policies. And I can promise you that if he were to do that here, he would be warned about it.

Well perhaps you are right. However, some people in

http://www.physicsforums.com/showthread.php?t=75197&page=3&pp=15

focused in stupid personal attack, and Lubos Motl indirectly entered in the convestation with a 'moo'. Curiosly D. Gross (Nobel laureate and one of leaders of string theory said similar stuff that i said. I wonder if Lubos would "moo" to David.)


I mean: Where are the references?

I replied above. I think that you have not problem in doing automated search in databases for obtaining papers or preprints. I'm sorry by the inconvenience.


OK, let's back it up a step or two. I find it difficult to accept this as a valid criticism. I can see how one might argue that the calculation you describe above is just too complicated to do with a theory as supposedly fundamental as string theory. What would you say to that? Are you saying that it is impossible to do such a calculation with string theory, even in principle? If so, then how do you know that?

This is a typical physicists' error. "Chemistry is reduced to physics but is computationally difficult". This is false. I was not talking about computational issues. I was saying that higher levels of matter have new information that cannot be reduced to low levels. The computation of RMN from strings is not a computational problem. The math involved in string theory is not sufficient. just an approximation, because algebra is more complex and above product is not computationally diffcult: it is not defined in string theory based in usual Hilbert space math.

the relation I+(rs)I+(tu) = I+(ru)delta(st) is not defined for wavefunctions in a Hilbert-Fock space). Therefore you cannot even formally represent a protein like a huge collection of strings, some what like you cannot represent they like a collection of classical particles. It is not about computational difficulty


Sure you may say it, but what's the reasoning behind your statements?

Universe is nonunitary, therefore string theory is in the wrong way. Search nonunitary theories used in laboratories of all world. I recomend to you look to Prigogine institute for example and search for his generalization of scattering theory.

[selfAdjoint]

Juan, can I jump in here for just one post? Our custom here at PF is that if you make a strong claim (which you have) it is your responsibiolity, not your readers' to come up with the citations, preferably online. So you claim that string theory not only does not explain or predict NMR results but that it cannot, that there is something wrong with it that prevents that. Well, give us a paper we can look at that explains why that is so, and doens't just baldly assert it. Or if you choose to explain this yourself, give us references (books should be OK in this case) to back up your derivations. In any case, you haven't done your job as advocate if when asked for backup you just shout louder. (Old math joke: paper found in great mathematician's notes for a talk: "Argument weak; use colored chalk.")

This is all said in respect for you, because I am not contradicting you, just asking you for what any professional seminar would.

[Nereid]

Some references would be nice.
I'm sorry, I have no time for providing you detailed references. I am very busy and have no time for searching now the papers, but most of i say is based in an abundant recopilated literature (physics, biology, ecology, physics, etc.) that i cited in several works, preprints, books, etc.
I am going to be considerably less polite than SelfAdjoint. :surprised

Juan R., if you are so busy, why are you wasting time writing posts in Physics Forums? Surely your precious time would be far, far better spent slaving over a hot sheet of paper, churning out revolutionary new theories of physics and piercingly accurate rebuttals of string theories? Or, perhaps, formatting your next great paper, in preparation for submission to PRL?

Now, before any reader reaches for the mouse to click the "Report" button, let me add that I greatly value Juan R.'s contributions to this thread, and PF in general; I am only calling him (?) to account on something he must surely have to hand (if he's serious, and is doing his own research, he will have to have these references before he can submit a paper in any case). Or, if not, then isn't reasonable to conclude it's little different from 'a snow job' (have I got the American idiom correct?)?

[Berislav]

Yes, i was refering to "correct" (2, 10) scan of supersymmetric version. Would you mind sharing with us what you found to be wrong with it?

Therefore, from "string theory unifies QM and GR" I never said that. :wink:

you now are broadly admiting that ST is, in fact, incompatible with GR I never said that, either. In fact, there exist formulations in which strings propagate in curved spacetime. For instance, http://arxiv.org/abs/hep-th/9112070.

Moreover, i believe that you ignores that, in the past, string theorists thought that full background invariance of GR was just a macroscopic approximation and initially they really thought that the split was correct. In fact, the perturbation of classical flat metric was interpreted like the real graviton. AFAIK, supersymmetry coupled with GR is the limit of superstring theory, but instead of Riemannian manifold, spacetime is a supermanifold (http://en.wikipedia.org/wiki/Supermanifold).

I was talking about compactification M10 -> R4 x M6.
Right then. What's wrong with that? The fibration of the four dimensions? The Calabi-Yau n-fold? Again, the same thing as with T-duality - can you show that something is wrong with those approaches?

P.S.
Also, Lindé doesn't seem to be completly against string theory:
http://arxiv.org/abs/hep-th/0503195

[Juan R.]

Juan, can I jump in here for just one post? Our custom here at PF is that if you make a strong claim (which you have) it is your responsibiolity, not your readers' to come up with the citations, preferably online. So you claim that string theory not only does not explain or predict NMR results but that it cannot, that there is something wrong with it that prevents that. Well, give us a paper we can look at that explains why that is so, and doens't just baldly assert it. Or if you choose to explain this yourself, give us references (books should be OK in this case) to back up your derivations. In any case, you haven't done your job as advocate if when asked for backup you just shout louder. (Old math joke: paper found in great mathematician's notes for a talk: "Argument weak; use colored chalk.")

I see no problem with the use of automated engines for search information (Note: I search information by myself without problems!!!). Since that I am very busy now with multiple occupations I leave the discussion. Perhaps in a future I can re-open it.


Juan R., if you are so busy, why are you wasting time writing posts in Physics Forums? Surely your precious time would be far, far better spent slaving over a hot sheet of paper, churning out revolutionary new theories of physics and piercingly accurate rebuttals of string theories? Or, perhaps, formatting your next great paper, in preparation for submission to PRL?

Now, before any reader reaches for the mouse to click the "Report" button, let me add that I greatly value Juan R.'s contributions to this thread, and PF in general; I am only calling him (?) to account on something he must surely have to hand (if he's serious, and is doing his own research, he will have to have these references before he can submit a paper in any case). Or, if not, then isn't reasonable to conclude it's little different from 'a snow job' (have I got the American idiom correct?)?

At my best knowledge nobody in the world is doing so many contributions to physics, chemistry, ecology, etc. Even people doing research in complexity is just focusing in one or two themes (e.g. vehicular traffic, virus disease, etc.). Sincerely, I was doing an effort for some people can obtain new ideas and was not misunderstand on ST (there are two ST, that appearing in popular books and talks and that shown in journals). Now, I will focus in pure scientific work. If you want learn some, please search in literature.


Would you mind sharing with us what you found to be wrong with it?


GR is not a perturbation around a flat metric. This is the reason that ST does not quantize gravity.


Therefore, from "string theory unifies QM and GR"
I never said that.

I do not said that! I mean

“Therefore, from [POPULAR STRING CLAIM] ‘string theory unifies QM and GR’ you now are broadly admiting that”


you now are broadly admiting that ST is, in fact, incompatible with GR
I never said that, either. In fact, there exist formulations in which strings propagate in curved spacetime. For instance, http://arxiv.org/abs/hep-th/9112070.


Yes, of course there are formulations of strings in curved spacetime. But that is not full compatible with GR. From ST, one cannot quantize gravity and this is the reason for the searching of an unknown M theory.


AFAIK, supersymmetry coupled with GR is the limit of superstring theory, but instead of Riemannian manifold, spacetime is a supermanifold.

It is not that. In the past, string theorists claimed that full GR was an approximation with an underlying classical metric in the style of QFT. Now are admitting that were wrong and one needs a new non-perturbative approach (that is not string theory). That is, LQG researchers were right. String theory does not quantize GR.


Right then. What's wrong with that? The fibration of the four dimensions? The Calabi-Yau n-fold? Again, the same thing as with T-duality - can you show that something is wrong with those approaches?

Compactification is done by hand. One does not derive GR from string theory, one force St to be compatible (so say) with GR. That is very different. In all applications of ST one choose the manifold by hand. That is not theory and precisely is linked to failure of string theory like a predictive theory. It cannot predict anything, new or no!

P.S:
Lindé, like many others (for example Hawking) is cautious. He is not “against” string theory, because he has studied string theory just from a single side (inflation and cosmology).

Moreover let me add that initial string aim was the substitution

Inflation (based in QFT) --> string theory cosmology.

Lindé shown that was very incorrect

“Steinhardt and Turok's idea sounds appealing, but fellow astrophysicists are not greeting it with open arms. "The community is very, very sceptical," says David Lyth, a cosmologist at the University of Lancaster, UK.

Others are more scathing. "It's a very bad idea popular only among journalists," says one of the chief critics of the cyclic model, Andrei Linde of Stanford University, California. "It's an extremely complicated theory and simply does not work," adds Linde, the originator of a rival model of the Universe.”

(http://www.nature.com/news/2002/020422/pf/020422-17_pf.html)

or

Another developer of the inflation model, Andrei Linde of Stanford University, takes a much dimmer view of the new work and has posted several papers on the Internet lambasting the ekpyrotic model. He says that to produce galaxies, Steinhardt and his colleagues have to choose a highly specialized, unrealistic form of interaction between branes. Moreover, Linde claims that the branes in the ekpyrotic model are not truly uniform in structure and therefore can't account for the large-scale uniformity of the universe.

"Instead of a theory, we have only wishful thinking," he says.

and now are researching other different thing

Old inflation --> string theory cosmology + inflation

Therefore from criticism Linde now is exploring new versions of modified string theory more inflation.

That is, string theory is modified for accounting (does not predict it!!) inflation. In fact, in the NC version one introduces the space-time expansion (with inflation or without) directly, by hand, in the equations of strings/branes, whereas the critical version ignores that fact and works with a fixed background without transitions between different vacua.


string theorists are arrogant enough that whatever comes up in their
research, they will call it string theory.

But history of the field is the history of successive failure.

[marcus]

Hi Berislav, I must say that I value both your and Juan R contribution here very much. Also I don't like to argue about whether "string is a waste of time". This is to be decided by those young researchers who have enough informed options to make a choice. I dislike arguments in general and ordinarily prefer to simply watch events and sometimes to report. Of course I hope that students choosing careers in research will have enough information and options open to them to chose intelligently.

Some things from your posts #7 and #13 caught my attention, Berislav. You were replying to Juan, whom I also quote here:


It has failed for quantize gravity (perturbative series is not well defined and nonperturbative regime is unknown),


It's true that there's no non-pertubative string theory.

it cannot explain GR (contrary to popular Witten claims string theory does not predict gravity, really string theory is adapted to previously known gravity), etc.


Doesn't massless spin-2 field work?






2) The perturbative splitting of metric is incompatible with GR; in fact, GR causality is not supported.

Since standard string theory is not backround independent and hence not complatible with GR to begin with the point is moot.


Here are the links to post 7 and 13 to give context, if anyone wants
http://www.physicsforums.com/showpost.php?p=677612&postcount=7
http://www.physicsforums.com/showpost.php?p=680638&postcount=13

It seems to me that you and Juan are discussing very fundamental issues (perturbative/nonperturbative issue, the issue that not being background independent implies not compatible with General Relativity).

Unfortunately, I thought, there was a purely verbal misunderstanding later where Juan said "from" where he should have said "instead of" or "in contrast to". I think you misunderstood what he was trying to say in post #16. Please correct me if I am wrong:




Since standard string theory is not backround independent and hence not complatible with GR to begin with the point is moot.

That contrast a bit with usual exagerated claims from string theorists. It is wel-known that Witten claimed in popular press that string theory predicts GR. In a recent Scientific American, B. Greene lists one of main advantages of ST over LQG the existence of well defined classical limit that is GR.

Therefore, from "string theory unifies QM and GR" you now are broadly admiting that ST is, in fact, incompatible with GR (just as relativist claimed for decades). Well, please explain that to miles of readers of string theory literature or just to editors of popular magazines like New York times or similar.


I think instead of "from" Juan meant this:
Therefore, in contrast to "string theory unifies QM and GR" you now are broadly admiting that ST is, in fact, incompatible...

It was just a problem with the preposition. I believe he meant in marked contrast to what String proponents have earlier said in public, you are now saying something different from that. He can correct me if I misunderstood him. Personally I think it is to your, Berislav's, credit that you take a different position from earlier proponents publicizing String. So pointing this out is really not a criticism.

[marcus]

What I mean is that Juan did not accuse YOU BERISLAV of ever saying
"string theory unifies QM and GR".
In fact you do not say this, that is something from the earlier publicity and the popularizations.
You say something different, that inasmuch as ST fails to be background independent, it is incompatible with GR.
If Juan accuses you of saying "string theory unifies QM and GR", then he is clearly wrong.


For my part, when I consider the topic of this thread Is String Theory A Waste of Time? I cannot think of this in a vacuum. I have to ask
COMPARED TO WHAT?

Since as a general rule, at least in the standard versions you have referred to, ST fails to be nonperturbative and background independent, I naturally compare it to the QG approaches featured in this conference

http://loops05.aei.mpg.de/

which are explicitly both nonperturbative and background independent.
By coincidence this is how the homepage defines the conference,namely
"the annual international meeting on non-perturbative/background independent quantum gravity"

There is some evidence that at least one of the approaches to be represented at the conference has desired classical largescale limit and semiclassical quantum cosmology behavior---also welldefined dynamics, by-passing some of the obstacles met by LQG.

[marcus]

Juan and Berislav both, here are 8 papers which appeared in the past 12 months all of which in different ways I think represent a change of the climate in which one asks "is ST a waste of time?"
http://arxiv.org/find/grp_physics/1/OR+OR+abs:+AND+triangulations+AND+Lorentzian+dynam ical+abs:+AND+triangulations+AND+causal+dynamical+ ti:+AND+gravity+AND+Lorentzian+quantum/0/1/0/past/0/1

the ones not by Loll are not necessarily to study (!) but they count because they are by newcomers (including several grad students and postdocs who just got into this line of research)

BTW if Juan's time does not permit him to continue this discussion, I will try to substitute for his side of the discussion (though perhaps in less argumentative style :smile:). I think important issues have been raised and maybe we can get some additional clarity about them.

[Berislav]

Hi Berislav, I must say that I value both your and Juan R contribution here very much. Also I don't like to argue about whether "string is a waste of time". This is to be decided by those young researchers who have enough informed options to make a choice. I dislike arguments in general and ordinarily prefer to simply watch events and sometimes to report. Of course I hope that students choosing careers in research will have enough information and options open to them to chose intelligently.
Thank you for your kind words.
I agree, this should be left to new researchers, which is what I hope to be one day. My problem is that now I am confused as to which approach I should pursue. I hope that things will become clearer in five years when I will have to make a decision.

I believe he meant in marked contrast to what String proponents have earlier said in public, you are now saying something different. He can correct me if I misunderstood him. Yes, it was most likely a simple misunderstanding.

There is some evidence that at least one of the approaches to be represented at the conference has desired classical largescale limit and semiclassical quantum cosmology behavior---also welldefined dynamics, by-passing some of the obstacles met by LQG. Very interesting. Are you refering to the approach you brought to attention in this thread: http://www.physicsforums.com/showthread.php?t=82129




Since Juan R. said that he has other obligations and can not discuss here at this time, I will retort to his post and await his return. :smile:

GR is not a perturbation around a flat metric. This is the reason that ST does not quantize gravity. In almost every text on GR one is first introduced to the curved spacetime as gravity method by pertubation around a flat metric. One is then convinced that the geodesic motion reduces to standard Newtonian mechanics. This is of course not general relativity, but my point is that since a perturbation as such does not account for all the phenomena that GR predicts one can not be sure that it will not be possible in the future. Perhaps this could be achived by some radical new discovery in differential geometry?


Compactification is done by hand. One does not derive GR from string theory, one force St to be compatible (so say) with GR. Yes, but compactification doesn't change the physics of the theory. That's why string theorists use the concept of fibrations, the functions defined on the spaces are topologically homotopic.

In all applications of ST one choose the manifold by hand. String theory allows different manifolds, but that doesn't mean that...

That is not theory and precisely is linked to failure of string theory like a predictive theory. It cannot predict anything, new or no! This is not true. For instance, D-branes wrapped over compactified dimensions act like black holes and predict black hole entropy. Astronomical observations seem to favor the existance of cosmic strings:http://arxiv.org/abs/astro-ph/0506400

That is, string theory is modified for accounting (does not predict it!!) inflation. In fact, in the NC version one introduces the space-time expansion (with inflation or without) directly, by hand, in the equations of strings/branes, whereas the critical version ignores that fact and works with a fixed background without transitions between different vacua. It seems to me that most of your objections to string theory stem from the fact that by itself it can't explain everything. IMHO, this is no reason to stop pursuing string theory as it would far too ambitious to require of the theory to be so fundamental, especially since everyone admits that is a work in progress.

[Berislav]

Juan and Berislav both, here are 8 papers which appeared in the past 12 months all of which in different ways I think represent a change of the climate in which one asks "is ST a waste of time?"
http://arxiv.org/find/grp_physics/1.../0/1/0/past/0/1 This looks very interesting.

BTW if Juan's time does not permit him to continue this discussion, I will try to substitute for his side of the discussion (though perhaps in less argumentative style ). I think important issues have been raised and maybe we can get some additional clarity about them. I will try to continue, but I don't think that I will be a match for you. :smile:

[marcus]

This looks very interesting.

I will try to continue, but I don't think that I will be a match for you. :smile:

come on Berislav, no false modesty here, you are great
:smile:

I dont pretend to debate with you, just to continue an interesting conversation
and others will come in and help out

[Tom Mattson]

I see no problem with the use of automated engines for search information

Juan, you've just been informed by 3 staff members that there is in fact a problem here. Claimants always either supply links or present full arguments. That is how we do things at PF. If you haven't got the time to present references (as marcus and Berislav do), then you haven't got the time to make claims such as the ones you have been making.

I really meant it when I said that I like what you are doing (attacking specific points), but you need to follow through on them with citations.

[Juan R.]

As already explained i was not acussing to Berislav.

Note: i already cited some known failures of ST beyond background independence and failure of compactification.


For my part, when I consider the topic of this thread Is String Theory A Waste of Time? I cannot think of this in a vacuum. I have to ask
COMPARED TO WHAT?

Compared to other less popularized approaches that advanced the field. Not only ST does not advanced physics, still it appointed to the wrong way and other theories did the work. In unification, TOE, quantum gravity, thermal phenomena, foundations of quantum mechanics, relativity, cosmology, etc. ST (and string theorists) did no contribution to physics.

String theorists simply copy the work done by others (and often copy incorrectly because have no idea of serious stuff).

[Juan R.]

Juan and Berislav both, here are 8 papers which appeared in the past 12 months all of which in different ways I think represent a change of the climate in which one asks "is ST a waste of time?"
http://arxiv.org/find/grp_physics/1/OR+OR+abs:+AND+triangulations+AND+Lorentzian+dynam ical+abs:+AND+triangulations+AND+causal+dynamical+ ti:+AND+gravity+AND+Lorentzian+quantum/0/1/0/past/0/1

Good references!

In fact, we did a joke of hep-th/0505154, in "Not Even wrong" some time ago.

Since that from recnt computaitonal work in triangulation approasch to QG author claim for a reduction of dimensionality on small scales we did the joke of (see my previous quote on arrogance of string theorists) how many time it would be need for that string theorists calimed that that result (2D) is obtained (predicted) from string theory.

[Juan R.]

In almost every text on GR one is first introduced to the curved spacetime as gravity method by pertubation around a flat metric. One is then convinced that the geodesic motion reduces to standard Newtonian mechanics. This is of course not general relativity, but my point is that since a perturbation as such does not account for all the phenomena that GR predicts one can not be sure that it will not be possible in the future. Perhaps this could be achived by some radical new discovery in differential geometry?

No!!! In "perturbative" GR causality is defined with respect to full metric g, not to flat metric h!!! There is no violation of GR by GR methods!!!!

String theory is different and inconsistent, this is the reason for searching of M theory.


Yes, but compactification doesn't change the physics of the theory. That's why string theorists use the concept of fibrations, the functions defined on the spaces are topologically homotopic.

No!!! String theory "predicts" 10D. Universe looks 4D. String theory does not explain why and compactification is forced by hand. That is not theory or derivation. Moreover, with each compactification one obtain a different universe (different physics) and the question is on choosing the correct physics "explaining" universe that we look. One is not obtaininr or predicting one is doing a kind of phenomenological adaptation (previous) of theory to reality. One need to know first the correct answer for "obtaining" it from ST. That is not physics!!

This is not true. For instance, D-branes wrapped over compactified dimensions act like black holes and predict black hole entropy. Astronomical observations seem to favor the existance of cosmic strings:http://arxiv.org/abs/astro-ph/0506400

No!!! prediction is when one take the theory and obtain a result, no when one know the result and force the theory (adapt it) to previously known result. Moreover, there is no serious astronomical observation of cosmic strings and "BH" "derived" in string theory are idealized models not the same BH predicted by GR (in fact this is a criticism by LQG, which work with GR BH).

Note: string theory desesperetely needs some empirical confirmation. Each certain time (since 20 years ago) a string is observed in some place. It is a recurrent theme somewhat like perpetual machines :-) I still remember past claims of first observation of cosmological strings...

It seems to me that most of your objections to string theory stem from the fact that by itself it can't explain everything. IMHO, this is no reason to stop pursuing string theory as it would far too ambitious to require of the theory to be so fundamental, especially since everyone admits that is a work in progress.

Everything? No!!! I am saying that all that work is a waste of time, like money, 30 years, and net results (zero) confirm. Even Lubos Motl admits that current string theory cannot predict anything (see my non-technical article).

It is wrongly developed with outdated concepts. It is not a TOE, in fact it is not even a correct apporach to quantum theory of gravity or to unification, as said in my firsts posts.

I call "a work in progress" when one introduces 5 (open) postulates and after of research one discovers that a postulate was wrong and other needed to be admended. That is WORK IN PROGRESS.

String theory is "to claim 5 postulates that explains all". No wait, are incorrect, claim other 5, not wait, now claim 6 postulates, not wait, now claim 3 postulates, not wait. Begin again, now claim 5 postulates for the Final Theory (this and this other guy are wrong), not wait they are not wrong, copy their work and to make a new theory. Huy, we forget this, copy this theory and launch a new theory...

The multiple (10^1) versions of the theory are my best proof. Moreover, string theorists are copying the work done by others and after rename like "string theory" (i even cited to a string theorist that admit this) and people (layman) think that WAS discovered by string theorists.

Open theory would be, for example

Universe dimension is 4D, not wait it is finally 5D. GOOD!!

String theory research look like

Universe dimension is 4D,

not wait it is 5D,

not wait it is 26D,

not wait it is 10D,

not wait it is 11D,

now there are people working in more that a time dimensions, whereas Segal claim that we are missing versions of 4D-string theory...

[Juan R.]

Juan, you've just been informed by 3 staff members that there is in fact a problem here. Claimants always either supply links or present full arguments. That is how we do things at PF. If you haven't got the time to present references (as marcus and Berislav do), then you haven't got the time to make claims such as the ones you have been making.

I really meant it when I said that I like what you are doing (attacking specific points), but you need to follow through on them with citations.

No problem!!!

I and others already know that string theory is a waste of time. During a time i followed the last fad in the theory but i discover that was a complete waste of time. Only "100" fanatics believes on them (i do not count layman who have no idea).

I waited to open a non-technical debate in this interesting topic. Especially seeing that some people contacted with me despite my criticism on string theory. Some young students are very confounded and begin a PhD in string theory...

Some years after they leave the field.

I respect you criticism to that i may suply correct links, full references. Ok i respect PF "policies". Of course, this is not the place for a thecnical discussion on string theory. It was no my aim!

I only was searching for some distended discussion. I'm sorry to say this but i do not see PF like a high thecnical forum for discussion of string theory and most of references that i would cite are very advanced.

Whereas the last fad in Dp-brane today is to substitute outdated Hilbert-Fock space quantization by doubled H-space and tilde operators (developed by other people of course), when that is already substituted in gluon-quark plasma by TFD-II or NESOM-TFD in doubled L-space because one cannot explain spacetime bubbles with the old approach.

If the most "advanced" noncritical formulation of "strings" one is substituting usual QM framework and evolution equations of standard ST by a mixture of open spacetime foam following Brushels formalism developed in 60s :surprised. But that formalism is outdated!!!! and now we are working in LPS in Gelfand triplets!!! Moreover, basic equation (10) of arXiv:hep-th/9403133 is incorrect. But author have idea of nothing and cannot see the errors. Of course, other parts of article are a complete nonsense. It is funy! String theorists are smart!

Schwartz and his infinite ignorance is still claiming for a unitary evolutor in the 2003!!

arXiv:astro-ph/0304507

When in the 70 we already discover that an unitary evolutor is a approximation to universe!!!

See p17 of

http://nobelprize.org/chemistry/laureates/1977/prigogine-lecture.pdf

Of course that work is outdated but was copied (incorrectly) in recent non-critical string theory.

In the last conference Quantum Future one heard


"Although much progress has been made, of course, in elaborating
the formalism, particularly in quantum field theory, its main elements, such
as the superposition principle and the probability interpretation as encoded in
the Hilbert space formalism, have been left unchanged. This is even true for
tentative frameworks such as GUT theories or superstring theory. Although the latter may seem "exotic" in some of its aspects (containing D-branes, many spacetime dimensions, etc.), it is very traditional in the sense of the quantum theoretical formalism employed."

(The black font is mine)

Of course string theory is fantastic!! String theorists are advancing science a lot of!!! In chemistry we are perplexed :rofl: of high mathematical level of string theory, so great that even cannot explain RMN protein formalism

http://nobelprize.org/chemistry/laureates/1991/ernst-lecture.pdf

(which is developed in L and S spaces and therefore does not reduced to string M-theory that need to be generalized, for example by crane theory (abandoned because string theory is wrong and i don't waste my time with it more) what is many times more complex that noncriticla string approsach which is, even in his more recent approaches, valid only in very idealized situations, e.g. markovian limit for vacuum transitions, commutative differential manifolds, linear approach for quantum states, second order in coupling contant, reducction of S-space algebra to minimum, idealization of states by stable quantum states (string theory based in QFT cannot explain rigogorusly instable quantum systems, look for Sudahshan work in Kaon systems, etc) etc, etc, etc, etc, etc.).


I'm sorry but this occupies to me many time and i leave this post now. If people want learn more please to search in literature.

[Chronos]

Nice try, Tom. I haven't succeded in getting Juan to explain how binary pulsar orbits decay without invoking gravitational waves. Specific questions seem to elicit vague replies.

[marcus]

Berislav, I want to congratulate you, since I have not yet done so, on your beginning your undergraduate physics studies as of this October.
Hope to see more of your posts and sometime to have chance for PF internet discussion

[Berislav]

No!!! In "perturbative" GR causality is defined with respect to full metric g, not to flat metric h!!! There is no violation of GR by GR methods!!!! Yes, you are right in that regard. The fact that you mentioned that leads me to think that you misunderstood what I was trying to point out. I was merely giving an example of how pertubations can work well in low-energy cases and hinted at the possibility that this could be exploited in some way in the future by string theory.

String theory is different and inconsistent, this is the reason for searching of M theory. Yes, string theory has it's problems.

No!!! String theory "predicts" 10D. Universe looks 4D. String theory does not explain why and compactification is forced by hand This is because compactification is one of the viable explanations as to why we observe the universe to have 3+1 dimensions.

Moreover, with each compactification one obtain a different universe (different physics) and the question is on choosing the correct physics "explaining" universe that we look. One is not obtaininr or predicting one is doing a kind of phenomenological adaptation (previous) of theory to reality. One need to know first the correct answer for "obtaining" it from ST. That is not physics!! It is the choice of the space on which the compactification is carried out which changes the properties not the compactification itself. But, I see your point - "trying out" different spaces until one finds the one that suits your theory is not a very exact method. Still, I don't think that it's a sufficient reason to dismiss string theory.

Moreover, there is no serious astronomical observation of cosmic strings With which part of the cited paper do you disagree with? That is, why do you think the observation mentioned in it is not a serious candidate?

and "BH" "derived" in string theory are idealized models not the same BH predicted by GR (in fact this is a criticism by LQG, which work with GR BH).
IMO, it can't be exactly the same black hole predicted by GR. After all, string theory should be a theory of quantum gravity.

I waited to open a non-technical debate in this interesting topic I don't think that's possible. Since you are questioning the worth of a theory, you will have to show why you think it's not credible and hence go into the technical aspects.

I'm sorry to say this but i do not see PF like a high thecnical forum for discussion of string theory and most of references that i would cite are very advanced. I'm not sure how I would fare against the full wrath of technicality, but many members here are very knowlegable, some are even experts so you don't have to hold back. :biggrin:
In fact I think that you should give some more concrete and detailed explanations as to why you think string theory is a lost cause, if your time permits it, of course.

Whereas the last fad in Dp-brane today is to substitute outdated Hilbert-Fock space quantization Quantization via Hilbert spaces is outdated? :confused:

Brushels formalism developed in 60s I have no idea what that is. :frown:


come on Berislav, no false modesty here, you are great
:blushing: Thank you for the compliment.

I dont pretend to debate with you, just to continue an interesting conversation
and others will come in and help out I look foward to it. :smile:

Berislav, I want to congratulate you, since I have not yet done so, on your beginning your undergraduate physics studies as of this October. Thank you.

Hope to see more of your posts and sometime to have chance for PF internet discussion I'm sure that I will benifit from and enjoy participating in PF's discussions during my undergraduate studies and hopefuly even later, as I did before.


P.S.
Juan, as I stated before, I don't know much about physical chemistry, so I can't comment on your other statements.

[mcgucken]

Does string theory have any postulates or laws?

Is string theory the first physical theory without postulates and laws?

I've been trying to find string theory's postulates and laws somewhere.

Thanks!

[Donski]

It seems that String Theory has no postulates nor laws. Does it even want postualtes or laws?

I only have one thing to say about strings, "lissajous", it's just an illusion so postulates and laws could expose it for what it is. :rolleyes:

[Icebreaker]

What sort of answer would sufficiently satisfy the question of "why" there are, for example, 10 spatial dimensions as opposed to any other number? Empirical evidence? Or some sort of mathematical deduction?

[ahrkron]

What sort of answer would sufficiently satisfy the question of "why" there are, for example, 10 spatial dimensions... ?

I think it needs to be two-fold: you'd need to show some basic principle to be true via experiment, and then find a solid argument showing that the same principle logically implies N dimensions (of course, this is a greatly simplified description).

[selfAdjoint]

I think it needs to be two-fold: you'd need to show some basic principle to be true via experiment, and then find a solid argument showing that the same principle logically implies N dimensions (of course, this is a greatly simplified description).

IF there were expeiments that validated superstring theory - a big if - then it would follow that there are 10 or 11 dimensions because superstring theory (resp M-theory) cannot live without 10 (resp 11) dimensions. That end of the inference is firm. The problem is to get superstring theory to make some distinctive and testable prediction.

[Juan R.]

With which part of the cited paper do you disagree with? That is, why do you think the observation mentioned in it is not a serious candidate?

If experimental data is correct, with the part, "Hey guy since we cannot explain, a priori, this data from 'usual' lensing thecniques, then that may be a cosmic string." This appears a joke, like the recent claim of string in a superconductor.

People is a bit exhausted of crankers. Somewhat like perpetual machines and cold fusion and all that.


IMO, it can't be exactly the same black hole predicted by GR. After all, string theory should be a theory of quantum gravity.

No. In LQG gravity one works with realistic BHs. In fact, one can derive the entropy for a Schwarzschild BH in the semiclassical limit. String theory does not work with realistic BH (in fact, ST works with noting real), it works just with a conjetured mathematical concept called BPS states. In the words of Smolin,


The results in string theory do not concern, precisely, black holes, as they are found in a limit in which the gravitational constant is turned off but they concern systems with the same quantum numbers as certain black holes

Those "BH" are not GR BH and are called extremal BH. Again string propaganda has effect...

Quantization via Hilbert spaces is outdated?

That standard quantization via the Hilbert-Fock space is outdated was well known for decades in other fields of science (people in other fields also use their brains :eek:).

See above link to Prigogine Nobel lecture for chemistry. String theorists, arrogant and ignorant as they are, claimed that all would be explained by ST a wonderful theory (they believed!!). Of course, people did mocking of that.

Now after of 40 years, they are begining to admit (so say, of course they do not say that others were corrects 40 years ago) that was completely wrong and the last fad is quantization via thermal spaces and tilde operators (they do not developed nothing of this).

Still that is not suficient (string theorists are really ignorant and crackpots :surprised ) but i suspect that around 2040 they will launch a new theory with ideas that others are working now.

[Juan R.]

Does string theory have any postulates or laws?

Is string theory the first physical theory without postulates and laws?

I've been trying to find string theory's postulates and laws somewhere.

Thanks!

Other theories have well defined laws, postulates, etc. For example LQG has well defined laws and experimental predictions.

In string theory there is no laws or postulates, just a mathematical gulash that is adapted each time that an inconsistency or sound error is found in the formalism. In fact, there is no real theory. String theory is a just program for searching a theory already called string theory. In M-theory is still poor. Nobody know that M-theory is, but it is claimed that is elegant :bugeye:

What arrogance!!

Since string theorists are arrogant crackpots with no idea like Nature work, they call string theory to ALL is introduced in string theory even if was developed by others (then they do not cite the source). A mathematician has confirmed to me this point in a personal mail, since mathematical work developed decades ago is being introduced now in M-theory like if it was invented by string theorists!!!

This begin to be admited even by some honest string theorists


string theorists are arrogant enough that whatever comes up in their
research, they will call it string theory.

Ethic (or absence of) apart, a Nobel Prize-winning physicist at Stanford admits

People have been changing string theory in wild ways because it has never worked.

For a simple non-technical review of dozens and dozens of string theories and why all failed please see www.canonicalscience.com/stringcriticism.pdf

[Juan R.]

What sort of answer would sufficiently satisfy the question of "why" there are, for example, 10 spatial dimensions as opposed to any other number? Empirical evidence? Or some sort of mathematical deduction?

i cited above Robert B. Laughlin (Nobel laureate) words.

String theory is best explained like the history of succesive 40 years failure. Nothing, absolutely nothing can be predicted or rigorously computed from string theory. All there exists is fascinating marketing program for laymen.

One of miths of string theory is that is not testable and then string theorist are forced to do research in difficult situations. Oh my God!

But it is false, as noted by Laughlin. String theory always was tested and all test invalid it. String theorists will say to you that whereas 4D dimensionality is introduced by hand in the standard model, 10 or 26 dimensions are required in string theory. Therefore, string theory is the best, best, best theory newer invented because provide answers to inimaginable question... Bla, bla, bla, bla, bla... Just propaganda.

Curiously string theorists omit to say to public why bosonic string theory needs of 26 dimensions. It is not a prediction (it is a needed) because other dimensionality is permited by the formalism.

But for D =/= 26 one finds either inconsistent answers or experimental violation, e.g. presence of tachions which are not observed in experiment (it would violates SR). Therefore the D=26 is the result of an experimental test.

The reduction to D=10 is the result of other experimental data (fermions), the compactification 10D -> 4D x 6D is the result of other experimental data (GR and experimental evidence of macrospacetime is for 4D), etc, etc, etc.

[selfAdjoint]

But it is false, as noted by Laughlin. String theory always was tested and all test invalid it. String theorists will say to you that whereas 4D dimensionality is introduced by hand in the standard model, 10 or 26 dimensions are required in string theory. Therefore, string theory is the best, best, best theory newer invented because provide answers to inimaginable question... Bla, bla, bla, bla, bla... Just propaganda

The bolded text is untrue. The extra dimensions ARE required by the stringy physics. Seems to me all you express in these posts is attitude, your own or somebody else's. There are pertinent things to say against string theory, but you haven't said them, and you can't as long as you refuse to couple to what the theory really says. I recommend Zweibach's book for a fast track introduction..

[Mike2]

The bolded text is untrue. The extra dimensions ARE required by the stringy physics. Seems to me all you express in these posts is attitude, your own or somebody else's. There are pertinent things to say against string theory, but you haven't said them, and you can't as long as you refuse to couple to what the theory really says. I recommend Zweibach's book for a fast track introduction..
So, selfAdjoint, did you ever finish Zweibach's book? Did you manage to do the exercises too?

[selfAdjoint]

So, selfAdjoint, did you ever finish Zweibach's book? Did you manage to do the exercises too?


Nope, too many other calls on my time. I am now TRYING to go through Peskin & Schroeder again. People tell me if you do it a second time the right way you can break through to real understanding.

[Juan R.]

The bolded text is untrue. The extra dimensions ARE required by the stringy physics. Seems to me all you express in these posts is attitude, your own or somebody else's. There are pertinent things to say against string theory, but you haven't said them, and you can't as long as you refuse to couple to what the theory really says. I recommend Zweibach's book for a fast track introduction..

Please read carefully my complete post before doing "incorrect" replies.

As said


Curiously string theorists omit to say to public why bosonic string theory needs of 26 dimensions. It is not a prediction (it is a needed) because other dimensionality is permited by the formalism.


I was expressing that popular idea of that 10D is a consequence of elegance of string theory is not true, since that dimensionality is forced to fit experimental data on tachions and others inconsistencies. Therefore, it is a adaptation of the formalism of string theory to available experimental data and not a question of mathematical elegance or a "derivation" from it.

Moreover, let me illustrate to you that some people is searching 4D versions of string theory like a form of eliminating compatification problems.

[Berislav]

If experimental data is correct, with the part, "Hey guy since we cannot explain, a priori, this data from 'usual' lensing thecniques, then that may be a cosmic string." Well, if it has the observed properties of a cosmic string.

In fact, one can derive the entropy for a Schwarzschild BH in the semiclassical limit. One can do that without quantum gravity. It can derived from QFT in curved spacetime, as done by Hawking. So, I really don't see your point.

String theory does not work with realistic BH (in fact, ST works with noting real), it works just with a conjetured mathematical concept called BPS states. In the words of Smolin,

Quote:
Originally Posted by Smolin
The results in string theory do not concern, precisely, black holes, as they are found in a limit in which the gravitational constant is turned off but they concern systems with the same quantum numbers as certain black holes


Those "BH" are not GR BH and are called extremal BH. Again string propaganda has effect...
If ST black holes were GR black holes then something would be wrong with ST. ST should be a theory of quantum gravity. If it predicted only GR black holes then it wouldn't be complete, because, for one thing, the BH wouldn't be quantizated.

That standard quantization via the Hilbert-Fock space is outdated was well known for decades in other fields of science (people in other fields also use their brains ). There's no reason for this and other insults. :frown:

Curiously string theorists omit to say to public why bosonic string theory needs of 26 dimensions. Insisting that the quantization be Lorentz covariant forces the 26 dimensionality (there are residual terms in the commutation of the Lorentz boost + angular momentum operator)

But for D =/= 26 one finds either inconsistent answers or experimental violation, e.g. presence of tachions which are not observed in experiment (it would violates SR). One finds a tachionic vacuum even when D=26 in bosonic string theory.



Nope, too many other calls on my time. I am now TRYING to go through Peskin & Schroeder again. People tell me if you do it a second time the right way you can break through to real understanding. Would this book be good after reading 't Hooft's lectures?

There are pertinent things to say against string theory, but you haven't said them, and you can't as long as you refuse to couple to what the theory really says. Quite. I'm still waiting for him to mention the Landscape. :biggrin:

[selfAdjoint]

Would this book {Peskin & Schroeder} be good after reading 't Hooft's lectures?

A friend told me the way to do a physics text was (a) Read through for meaning, and don't worry about derivations or excercises), then (b) read again doing the derivations if possible and getting someone to help you if you run into trouble, and finally (c) do the excercises with the same stipulations as (b). So right now I am finishing up (a) on chapter two of P&S and next weeek I'll start on (b). This is where I fell down before, but now I have people who can help me. If I can get over this hump, I am hoping I can eventual go forward on my own. It's "the tricks of the trade" that give me problems.

Whether it would be good after 't Hooft depends on what you want. P&S is oriented to giving you the capability of doing relevant calculations: N point functions, crossing symmetries, cross sections, lifetimes, et al. It's a real working physics text.

[Juan R.]

Well, if it has the observed properties of a cosmic string.

Yes, if. The idea of observed strings (like the idea of observed supersimmetry) is recurrent. It sound like perpetual machines invented each some time by guys, or like the experimental "proofs" of violations of the second law. The last "proof" i know was published in 2002 in PR.

Already in 1986 Paczinski published a paper suggestinge that several large separation gravitational lens candidates could be explained by the existence of cosmic strings. It was very popular then, because a lens with such a large separation is difficult to explain with unseen conventional objects and requires a large mass to light ratio for the lens. The first cosmic verification of string theory. Whow!!

Subsequent observations suggested that the quasar pair was not lensed!

Moreover, even if data is correct, the claim that one could explain that from a string theory is, obviously, a nonsense. It is a waste of time :yuck:


One can do that without quantum gravity. It can derived from QFT in curved spacetime, as done by Hawking. So, I really don't see your point.

Rigorously? does he not used quantum gravity? Also logaritmic corrections? If it is so simple, why is the derivation of "BH" entropy claimed to be one of main successes of ST, e.g. in the Elegant Universe?


If ST black holes were GR black holes then something would be wrong with ST. ST should be a theory of quantum gravity. If it predicted only GR black holes then it wouldn't be complete, because, for one thing, the BH wouldn't be quantizated.

1) Correspondence principle 2) one may derive the proportionality factor and a counting of the microscopic states of entropy. ST may explain GR black holes, not idealized (extremal) "BH" which are not studied (predicted) in Eintein GR.

You claim is completely wrong. If ST was only a theory of quantum gravity as you claim, then would be a nonsense the ST popular claim of derivation of Einstein field equations and the string criticism to LQG of that still cannot derive them.

LQG does not predict only GR black holes, as already said, but ST cannot obtain GR black holes. You would be not hungry with me if ST is a waste of time.


There's no reason for this and other insults. :frown:


There exist not insults on


That standard quantization via the Hilbert-Fock space is outdated was well known for decades in other fields of science

or


(people in other fields also use their brains ).

but the the string philosophy of

i-have-no-idea-of-you-are-working-but-my-theory-is-the-most-fundamental-possible-
and-you-are-doing-nothing-important

expresed elocuently by


string theory continues to show ever increasing signs of being the
correct approach to understanding nature at its most fundamental level.

Or the talk/book popular claim of string theory "is the only approach to quantum gravity" is also other form of insult, it sounds like "hey guy your decades of work on loops are nothing."

There is dozens of insults, like the idea of people that does not study string theory is not smart. One recent is the following


For five years, I and Lubos have disagreed about the consistency of gauge anomalies. His argument was always "A gauge symmetry is a redundancy of the description, you idiot". With my last post, I think I convinced him that he was wrong, since a counterexample can be found in the most elementary chapter of GSW.

One first step in the developing of a new theory is to know that is being done in the field by others. In fact, this basic principle of scientific research is just ignored by crackpots and hoaxes like Peter Lynds.

If Ed Witten claim, in a popular interview, that all of chemistry is already reduced to physics and he has not studied chemistry seriously and newer read articles in Foundation of chemistry (for instance), then he is not different (here) from other hoaxes or crackpots.


Insisting that the quantization be Lorentz covariant forces the 26 dimensionality (there are residual terms in the commutation of the Lorentz boost + angular momentum operator)

As said if D=/=26 either you obtain an inconsistent theory or violating experimental data one, e.g. special relativity. There is no special elegance in D=26 version, the result obtained from string theory are not elegant ones, just the result of adapting it to experimental data known. As brilliantly explained by Nobel laureate i cited above, string theory is modified each x time because it has newer work. Moreover the idea of string theory is untestabel is another mith. If was untestable, one would not worry of failure of Veneziano formula for describing correctly the cross sections that we observe, unseen tachionic behavior, or compactification, or supersimmetry (also unobserved), or p-branes, etc.

All of that added for compatibility with experimental data

People is being just misinformed. Take like the last example that i known, the recent Sean article in cosmic variance (http://cosmicvariance.com/2005/07/21/two-cheers-for-string-theory/)

Whow, that fantastic sound string theory in popular press!!!

But when you read comments on the blog you discover that almost all is either completely wrong or exagerated. It is impressive like Sean talk about things that he does not know (increasing the miths about string theory between laymen).

I posted a long reply. I said to Sean that he is misguiding several importants points, e.g. she does not notice that today string theory is not a theory of strings.

String theorist Lubos Motls has posteriorly said the same in his own blog

http://motls.blogspot.com/2005/07/strings-as-microsoft.html

I repeat again all past claims of string theorists were false and the name string theory is leaved by marketing purposes.


One finds a tachionic vacuum even when D=26 in bosonic string theory.

Yes, but whereas one could attempt to "re-absorved" it in a vacuum redefinition, there are not posibilities for advancing already with the first excited state, and D=26 arises due to violating of experimental data known.

[Berislav]

Subsequent observations suggested that the quasar pair was not lensed! Yes, but until further data debunks the paper I mentioned there is no reason to think that it is not a credible observation.

If it is so simple, why is the derivation of "BH" entropy claimed to be one of main successes of ST, e.g. in the Elegant Universe? I'm not sure. Maybe it's because string theory predicts a phenomena that is derived from an established theory which boarders with quantum gravity.

As said if D=/=26 either you obtain an inconsistent theory or violating experimental data one, e.g. special relativity. That's seems like a weird statement to me. It's like saying that QFT is wrong because Feynman's invariant perturbation formulation is only adapting it to special relativity.

If ST was only a theory of quantum gravity as you claim, then would be a nonsense the ST popular claim of derivation of Einstein field equations and the string criticism to LQG of that still cannot derive them. I would like to see some references to the contrary.



Whether it would be good after 't Hooft depends on what you want. P&S is oriented to giving you the capability of doing relevant calculations: N point functions, crossing symmetries, cross sections, lifetimes, et al. It's a real working physics text. I see. Thank you for the information. I think that I will purchase it sometime in the near future.


A friend told me the way to do a physics text was (a) Read through for meaning, and don't worry about derivations or excercises), then (b) read again doing the derivations if possible and getting someone to help you if you run into trouble, and finally (c) do the excercises with the same stipulations as (b). It sounds like good advice. I too will try to use that method.

[Chronos]

But when you read comments on the blog you discover that almost all is either completely wrong or exagerated. It is impressive like Sean talk about things that he does not know (increasing the miths about string theory between laymen).So Sean Carroll is the latest addition to your wax museum of scientists who don't know what they are talking about? Absurd, but still hilarious.

[Juan R.]

Yes, but until further data debunks the paper I mentioned there is no reason to think that it is not a credible observation.

I agree. Simply i said that the asumption of that that effect was predicted from string theory is wrong, because from string theory one cannot predcit anything (see also Lubos Motls comments on his blog below or quote in my non-technical article www.canonicalscience.com/stringcriticism.pdf in its four page).


I'm not sure. Maybe it's because string theory predicts a phenomena that is derived from an established theory which boarders with quantum gravity.

No, string theory does not predict that result, string theory is adapted to that previously known result. Moreover, as already said one only obtain a numerical coincidence with entropy of GR BH, because, string theory does not work with GR BH, unlike LQG.


As said if D=/=26 either you obtain an inconsistent theory or violating experimental data one, e.g. special relativity.

That's seems like a weird statement to me. It's like saying that QFT is wrong because Feynman's invariant perturbation formulation is only adapting it to special relativity.

No! You are not fixing the point.

If you develop a QFT violating SR, then you are developing a wrong theory, because violates experimental data known. Then one formulates a QFT consistent with SR postulates and the bundle is called relativistic QFT. OK?

Now turn to ST. You can mathematically develop bosonic ST for D=4, D= 9, D=236945, etc. The point is that for D < 26 you obtain tachionic behavior and this is incompatible with SR (you obtain imaginary masses states). Then you force your bosonic theory to D=26. Therefore, D=26 is not an elegant derivation from string theory as is claimed in talks or oriented laymen books. Simply the result D=26 is an adaptation of ST to experimental data known. That is, it is a test of ST.

This is an important point, because the history of ST is the history of succesive experimental failure. Veneziano formula was invalidated experimentally, and abandoned by QCD.

Then people suggested a generalization to gravity (string theory was not only a theory of strong force they claimed). Bosonic string theory in 4D is experimentally inconsistent and then one introduces 26D, but our world is 4D (that is another violation of experimental data) and one introduces Kaluza-Klein (that in original unification scheme predicted "Dicke" scalar field not experimentally found) and one obtain again inconsistency with experimental data and then one add supersimmetry (newer experimentally found where "predicted" and then the scale of energy increased by hand several times for consistency) and posibility for fermion families (string theory was not only a theory of strong force more gravity they claimed)) and again one obtain an experimentally inconsistent theory (nobody has shown breaking of supersimmetry to low energies required by experimental data) and after of more than 30 years...

Finally one obtains a perturbative series that nobody has shown to be convergent for a theory (of everything) in a classical flat metric with perturbation, but again this is experimentally incorrect, since GR claims that causality is defined on curved g metric not on a flat n metric and then people searchs for M-theory that nobody knows that is but all people agrees that is not a theory of strings.

Note: In the past, string theorists claimed that one would not take GR seriously and one would define causality on the flat metric with graviton like a perturbative addition. Still yesterday James Graber has claimed in Cosmic variance (see above link) that


That is, despite the observational confirmations of General Relativity predictions and the success of Inflationary ideas, it still appears that we live in a flat universe. The fact that quantum mechanics is so hard to formulate in curved spacetime may be telling us that we live in a universe that is necesarily exactly flat, not just approximately flat, or accidentally flat. Perhaps the universe is not background independent, but rather requires a flat background.

Which is obviously a complete nonsense and by this reason people is searching a M-theory. That is string theory is the history of succesive failure, and string theorists simply are modifing their ideas to ideas expreseed previously by others.

Still Hilbert-Fock quantization of string is incompatible with experimental data on quark gluon plasma and now people is using doubled quantization and tilde operators in a new version of Dp-brane theory, but that new quantization methods were not originated on string theory they were in plasma physics, etc.

And recent noncritical approach in Gelfand triplets is also wrong and violates basic experimental stuff known in other fields, etc.

and recent unitary theorems (including unitarity in BH evaporation) are wrong with well-known material in chemical physics (see Nobel lecture that i cited above). a simple electron transfer reaction already violates superstring theory and recent Schwartz (2002) claims.

Etc, etc, etc.

Since that string theory is a waste of time, there is a joke that said that recent failure of string theory in cosmology ("complete failure" according to cosmologist Krauss who is writting a book about the joke called string theory) implies that string theory was not a theory of everything it was really a theory of more than everything.



I would like to see some references to the contrary.

I do not understand. Contrary to what?

[Juan R.]

So Sean Carroll is the latest addition to your wax museum of scientists who don't know what they are talking about? Absurd, but still hilarious.

Nice comments Chronos! Let me quote to Lubos Motl (from link above).


Also, another problem with Sean's text is that he paints string theory as we knew it 20 years ago or so.

And


Today, string theory is not just a theory of strings.

And, also,


Today, "string theory" is a kind of misnomer.

It is also interesting the real status of string theory like a theory of everything where one is deriving all, including cosmic strings.


But in order to achieve the goal fully, it should also be used to derive the right spectrum of particles with the right parameters either from no input or from a smaller set of assumptions than required by the previous theories.

Today, "string theory" cannot predict anything of this world, it is not a theory, it is not based in strings, and Sean would remain silent...

[brunardot]

Other theories have well defined laws, postulates, etc. For example LQG has well defined laws and experimental predictions.

In string theory there is no laws or postulates, just a mathematical gulash that is adapted each time that an inconsistency or sound error is found in the formalism. In fact, there is no real theory. String theory is a just program for searching a theory already called string theory. In M-theory is still poor. Nobody know that M-theory is, but it is claimed that is elegant :bugeye:

What arrogance!!

In general, I agree with your statement; however:

From ST, that is, the logic of the geometry of the strings' formation and coalescence, Pauling, shortly before his death, indicated that he agreed that one might predict the mechanics of bonding . . . as applicable to subatomic bonds, atomic bonds (5 chemical bonds), including the Bjerknes hydrodynamic “action-at-a-distance” effect, van der Waals forces, and the Casimir force.

[Juan R.]

In general, I agree with your statement; however:

From ST, that is, the logic of the geometry of the strings' formation and coalescence, Pauling, shortly before his death, indicated that he agreed that one might predict the mechanics of bonding . . . as applicable to subatomic bonds, atomic bonds (5 chemical bonds), including the Bjerknes hydrodynamic “action-at-a-distance” effect, van der Waals forces, and the Casimir force.

?

A related question for you:

What is a bond?

[Juan R.]

Some people claim in Cosmic variance for experimental observation of decreasing of newtonian force at short scales. If true this would be the final knock to string theory before the well-known claim of that string theory will be finished at HLC.

String and M-theories "predicts" strong effective gravitational interaction to shorter distances.

Somewhat like the rule 1/r^(2+d) for d extra dimensions (some recent RS brane model introduces Yukawa like exponential correction from extra 5th dimension).

I will say next is not rigorous but intuitive.

We can observe that smooth behavior is obtained formally with

d < 0 for r –> 0 on 1/r^(2+d) for d "extra" dimensions.

It is interesting the chossing d = -2 for short scales (dimensionality in string M theory is fixed to 10-11D but it is not in other advanced approaches) because:

i) It is compatible with recent advances in triangulations quantum gravity (hep-th/0505154). Where dimensionality of spacetime is reduced not increased to short scales.

That is, Calabi-Yau manifolds conjeture vanishes and all formalism of string theory turns wrong. Moreover spacetime become fractal to shorter scales and therefore the use of differentiable manifolds (CY, G2) on string, brane, and M theory again is an oudated (wrong) method.
Again i was correct and string M theorists (of course smart as they are :-) completely wrong.

As explained in April www.canonicalscience.com/stringcriticism.pdf

I and others are working in nondifferentiable manifolds time ago, but string theorists (irrelevant and ignorant as they are) still believe that one can model universe using a CY (10D string theory) or recent M2 manifolds (in 11D M-theory).

Above June preprint exposes ideas similar to derived from canonical science: fractality and non-diferentiability.

ii) d -2 for r –> 0 imply formally elimination of divergencies on (1/r^2) force strengh since (1/r^2) —-> (1/r^0) and this would permit to us the developing of a non-divergent full quantum gravity.

[Berislav]

Simply i said that the asumption of that that effect was predicted from string theory is wrong, because from string theory one cannot predcit anything (see also Lubos Motls comments on his blog below or quote in my non-technical article I disagree. String theory predicts the existance of cosmic strings. The newly discovered phenomena can be interpreted as a cosmic string and to my knowledge not as anything else, for the time being, at least.

No, string theory does not predict that result, string theory is adapted to that previously known result. I will respond to this issue later. Since I can't find any references at this time.

Now turn to ST. You can mathematically develop bosonic ST for D=4, D= 9, D=236945, etc. The point is that for D < 26 you obtain tachionic behavior and this is incompatible with SR (you obtain imaginary masses states). Bosonic string theory is devoloped by at first leaving the number of dimensions unknown. One then (as I said before) because of unphysical (as you say, tachionic) residual terms in the commutation relation of the Lorentz boost and angular momentum operator imposes the 26 dimensionality. The residual terms are then zero. I don't see anything wrong with this. Maybe it isn't "elegant", but then again that is a subjective concept.

and then one add supersimmetry (newer experimentally found where "predicted" and then the scale of energy increased by hand several times for consistency) and posibility for fermion families (string theory was not only a theory of strong force more gravity they claimed)) and again one obtain an experimentally inconsistent theory (nobody has shown breaking of supersimmetry to low energies required by experimental data) and after of more than 30 years... Aha. So you dislike supesymmetry as well as string theory. :grumpy:

Still Hilbert-Fock quantization of string is incompatible with experimental data on quark gluon plasma and now people is using doubled quantization and tilde operators in a new version of Dp-brane theory, but that new quantization methods were not originated on string theory they were in plasma physics, etc.

And recent noncritical approach in Gelfand triplets is also wrong and violates basic experimental stuff known in other fields, etc. I don't know about those approaches. I do know however about the BRST formalism, which is a supersymmetry! And to my knowledge works quite well.

I do not understand. Contrary to what? Contrary to "the ST popular claim of derivation of Einstein field equations". That is, that supersymmetry coupled with gravity isn't the low energy limit of superstring theory.

Some people claim in Cosmic variance for experimental observation of decreasing of newtonian force at short scales. This sounds like a very important discovery! I thought that we couldn't reach the necessary energy to observe such radical changes in the laws of spacetime. Some references, please!


In general, I agree with your statement; however:

From ST, that is, the logic of the geometry of the strings' formation and coalescence, Pauling, shortly before his death, indicated that he agreed that one might predict the mechanics of bonding . . . as applicable to subatomic bonds, atomic bonds (5 chemical bonds), including the Bjerknes hydrodynamic “action-at-a-distance” effect, van der Waals forces, and the Casimir force.

?
I agree with Juan R. :biggrin:

[mcgucken]

The beautiful paradox of String Theory is that anyone dumb enough to devote 30 years of their life to a non-theory--a theory without postulates, laws, and experimental evidence--will also be dumb enough to defend that theory to the death.

[brunardot]

?

A related question for you:

What is a bond?

A bond, as originally referenced herein, must be a physical manifestation, as must all phenomena . . . unlike currently proposed “action-at-a-distance.”

A bond is an attractive force that arises from the motion of energy when that energy is such that it is trying to separate that which intrinsically resists separation because of counter forces or the intrinsic nature of the source of that which will not separate.

Fundamental bonds are interacting, hyper-relativistic, complex-oscillating solitons that are within and without the nucleus of an atom. “Dark” energy is an extreme example of this solitonic phenomena as heuristically described by Taisoids. See: http://www.2-CQ.info/TaisoidDiscussion/

The beautiful paradox of String Theory is that anyone dumb enough to devote 30 years of their life to a non-theory--a theory without postulates, laws, and experimental evidence--will also be dumb enough to defend that theory to the death.

I have similar sentiments concerning the defense of paradigms that do not internally reconcile, do not reconcile with one another, and only reconcile with observation within narrowly, contrived parameters.

Concerning alternative theory, as per Weinberg's "new physics," Planck appears to have it right with his pessimism concerning "scientific innovation."

[RandallB]

Concerning alternative theory, as per Weinberg's "new physics," Planck appears to have it right with his pessimism concerning "scientific innovation."Was able to find Plank's quote - that is pessimistic !–
I hope it isn’t really that bad when something well documented and verifiable is brought forward. I know it took some time for Einstein but as verification came in the majority of those disagreeing with it accepted relativity rather than disappearing – some maybe never did.
I’d hope things would be better now.

As to Weinberg's "new physics" comment.
I assume your referring to the one in the Bryce DeWitt Physics Today article Jan 2005. Also rather pessimistic.
I'd hope we can all do better than that.

RB

[brunardot]

Was able to find Plank's quote - that is pessimistic !–
I hope it isn’t really that bad when something well documented and verifiable is brought forward. I know it took some time for Einstein but as verification came in the majority of those disagreeing with it accepted relativity rather than disappearing – some maybe never did.
I’d hope things would be better now.

As to Weinberg's "new physics" comment.
I assume your referring to the one in the Bryce DeWitt Physics Today article Jan 2005. Also rather pessimistic.
I'd hope we can all do better than that.

RB

Weinberg has been calling for the apparent need for a "new physics" since before "Dreams of a Final Theory," 1992.

Einstein was never personally accepted by American academia. A special institute (IAS) had to be built just for him because, as an outsider, he was not personally acceptable within the "Halls of Academia." His Nobel was given as a "slap in the face"; as, he didn't believe in QM for which he set the ground work; and, was so rewarded. SR and GR never earned him a Nobel . . .

As for someone coming forward that is "well documented and verifiable"; they must pass peer review to be so qualified. Peer review is a conspiracy to protect the sinecure of those threatened by such a Paradigm Shift.

I am nothing but pessimistic in the vein of Planck.

An important scientific innovation rarely makes its way by gradually winning over and converting its opponents: it rarely happens that Saul becomes Paul.

What does happen is that its opponents gradually
die out and that the growing generation is familiarized with the idea from the beginning.

Max Planck [1858-1947]
The Philosophy of Physics, 1936

Carefully examine the logic of the posts at the two closed threads in this forum at: Number Theory, 1.) An elliptical constant; and, 2.) Is -1 a prime number?

Then compare the above, by clicking the below link, to the open-minded expression that is viewed elsewhere for discussion.

Number Theory (http://www.2-CQ.com/Number_Theory)

Truth will out when the marketplace for ideas is open and free flowing.

"Ye shall know the truth, and the truth shall make you mad." -Aldous Huxley

[selfAdjoint]

Einstein was never personally accepted by American academia. A special institute (IAS) had to be built just for him because, as an outsider, he was not personally acceptable within the "Halls of Academia." His Nobel was given as a "slap in the face"; as, he didn't believe in QM for which he set the ground work; and, was so rewarded. SR and GR never earned him a Nobel . . .

The statement about the Institute for Advanced Study is wrong. When the IAS was planned, Einstein was still an apparently contented Professor at Berlin; it was only after it had been created and had its first members (the American mathematician Otto Veblen and others), that the Hitler regime come to power and Einstein was forced to leave Germany. The IAS leaped at the opportunity to offer the most famous physicst in the world a place.

I well remember that Einstein had a much better reception in "red state" academia than did Quantum Mechanics. Indiana University, for example had Vaclav Hlavaty, a worker in Einstein's Unified theory in the 1950s, but the physics department was trying mightlily to establish a modern classical physics tradition to compete with QM, for which not one course was given.

[brunardot]

The statement about the Institute for Advanced Study is wrong. When the IAS was planned, Einstein was still an apparently contented Professor at Berlin; it was only after it had been created and had its first members (the American mathematician Otto Veblen and others), that the Hitler regime come to power and Einstein was forced to leave Germany. The IAS leaped at the opportunity to offer the most famous physicst in the world a place.

I well remember that Einstein had a much better reception in "red state" academia than did Quantum Mechanics. Indiana University, for example had Vaclav Hlavaty, a worker in Einstein's Unified theory in the 1950s, but the physics department was trying mightlily to establish a modern classical physics tradition to compete with QM, for which not one course was given.

At my age, details often slightly transmute from conversations with Philip Morrison 50 years ago.

IAS was incorporated May 20, 1930; but did not open its doors until 1933, at which time Albert Einstein was its first professor.

[Juan R.]

A bond is an attractive force that arises from the motion of energy when that energy is such that it is trying to separate that which intrinsically resists separation because of counter forces or the intrinsic nature of the source of that which will not separate.

Fundamental bonds are interacting, hyper-relativistic, complex-oscillating solitons that are within and without the nucleus of an atom. “Dark” energy is an extreme example of this solitonic phenomena as heuristically described by Taisoids.

Only can say
!


P.S: Drugs are not good :yuck:

Intrinsically of course

[Juan R.]

As said from string theory, one cannot predict anything. This irritatting point begins to be broadly admitted by most honest string theorists.

That experimental observation, if real, cannot be explained from string theory but, and this is my point, you can modify string theory for adapting it to that data once you know that data. Historically that was the way.

You appears rather confounded, I recomend to you The book “Hiding in the Mirror: The Mysterious Allure of Extra Dimensions,” to be published this year by Krauss.

Krauss, a leading expert on cosmic dark matter and dark energy, argues that string theorists have produced no satisfactory explanations for anything.

That is, basically, I said in April.


Bosonic string theory is devoloped by at first leaving the number of dimensions unknown. One then (as I said before) because of unphysical (as you say, tachionic) residual terms in the commutation relation of the Lorentz boost and angular momentum operator imposes the 26 dimensionality. The residual terms are then zero. I don't see anything wrong with this. Maybe it isn't "elegant", but then again that is a subjective concept.

I will explain again. String theorists claimed to public that theory was elegant; all was fixed in the theory in a natural manner (still people believe that string theory contains a single parameter), and cannot be experimentally tested.

Reality is as follow. You begin from a 4D formulation (initially people did not leave dimensionality unknown) but quantizing the open bosonic string, you obtain the spectral decomposition for the first excited state.


m^2 = (2 \pi T_{0}) \left[1 - \frac{D-2}{24}\right]


For D<26 you obtain violation of Lorentz invariance, and for D>26 you obtain negative square mass states and by Einstein mass formula


m = \frac{m_{0}}{\sqrt{1 - \frac{v^2}{c^2}}}


tachionic behavior (v > c). Both behaviors are not observed in nature (the tachionic behavior of ground state is ignored now), therefore the result D=26 is the direct outcome of a direct experimental test of string theory. String theory may be consistent with previous theories, which explain past and present experiments. E.g. choosing D=4, bosonic string theory cannot explain data that special relativity already explain.

Since 40 years ago, string theory has been experimentally tested and modified for adapting it to known data. This is the point that string theorists fail to adequately explain to people, young students, etc.


Aha. So you dislike supesymmetry as well as string theory.

Physics is not about like or dislike. Physics may explain the world we know. The world that we know does not provide signs of multidimensional strings or supersymmetric states.

Until now, all our experience is about non-supersymmetric universe in 4D. A honest physicist would construct a theory for a non-supersymmetric universe in 4D and after if one day additional dimensions or supersimmetry are discovered then generalize the framework. But string theorists first developed a mathematical theory for 26D and then began the 40-years dark age.

Remember that supersimmetry was added to string theory for solving some of its consistency problems and violation of experimental data.

All of string theory is about add, and add, and add, and add until that one day you obtain a theory that nobody know, is not defined, it has so many conjectures, unproved beliefs and open questions that can say anything and the contrary of anything. For example, if supersymmetry is not observed in next accelerator generation, then string theoreticians will be invoke a new change of scale (as in the past) or will add some new mathematical device that “cancels” it. The “theory” (so say) is permanently in a safe state.


I don't know about those approaches.

Ok, but people working in other fields knew it, and those true physicists developed those fantastic approaches without pompous claims such as that of Brian Greene and friends. String theorists, arrogant as they are, claimed that all was already known and explained by string theory: the most important theory! The Last formulation!

if I remember correctly, they discovered that traditional quantization is not sufficient 5 years ago, and now are adaptation previous old version of brane theory to new formalism as explained in article. Still today, they are working with the simplest version of formalism (developed 20 or 30 years ago by others) now we are working with new more general theories. Perhaps by 2015, some string theorist will say “hey guys, this is not rigorous, we may use this theory” (we are working today) for obtaining the 123th version of string theory.


Contrary to "the ST popular claim of derivation of Einstein field equations". That is, that supersymmetry coupled with gravity isn't the low energy limit of superstring theory.

From ST one cannot derive GR.


This sounds like a very important discovery! I thought that we couldn't reach the necessary energy to observe such radical changes in the laws of spacetime. Some references, please!

As said it is a rumor, there is not paper still, but is appears that result is solid.
It seems that deviations from Newton's gravitational law at distances slightly below 100 microns were detected at the "4 sigma" confidence level. Since assertion would be revolutionary an increase to "8 sigma" is being worked. Traditionally string theory has claimed for the contrary fact, (I even have seen the r^-7 corrections to Newtonian potential from Matrix theory) but don’t worry, if finally true, string theorists will invoke some new mathematical device for saving string theory again. That is will develop the 45th version of the “theory”.


People have been changing string theory in wild ways because it has never worked.

[RandallB]

His Nobel was given as a "slap in the face"; as, he didn't believe in QM for which he set the ground work; and, was so rewarded. SR and GR never earned him a Nobel . .Somebody gave you a bad "time line" on this as well.
His Noble Prize was in 1922. Quantum Mechanics didn’t start until 1925/26.

Quantum Physics is not incompatible with Classic Physics. Just as relativity is “classical” so is Quantum Physics, as Einstein choose to continue to work on it, is “classical”.
It is the Quantum Mechanical interpretation and explanation of Quantum Physics that is non-classical due to the uncertainty issue, as are theories that grow from it like Strings.
Is it frustrating, sure, most honest QM’ers admit it is too, but they work with it because it works.

The biggest problem I see with most opposition to QM is that they just oppose, or produce something with no real foundation (Classical or QM), but instead an even more bizarre foundation than uncertainty.

As to strings being a waste,
maybe some of the extreme versions are, but the idea has set some additional higher standards that any future explanation needs to cover in order to be a replacement theory.

For example:
Strings has been shown to be dependent on having 6 additional dimensions. However, that allowed for at least 5 “string viable” independent interpretations that couldn’t be reconciled until one more dimension was added, “M Theory”, for a total of 11.
To me this means a complete theory, be it classical or QM, must explain:
A) If real – Show where these extra dimensions are and what they do.
OR
B) If not real – explain why it appeared they were real.

Does this set the bar higher and more difficult?
Or is it more information and data that will helpful in reaching the goal?

I think it can be helpful, trick is figuring out how to climb the data.

RB

[brunardot]

As said from string theory, one cannot predict anything. This irritatting point begins to be broadly admitted by most honest string theorists.


ST can predict much with slight adjustments in the theory.

Like for instance: the internal geometry of the "strings."

Unfortunately, its predictions cover the gamut of current enigmas, which theoretical physicists are loathe to discuss in detail. Probably, for fear their house of cards and their grants and sinecures will fall.

[Juan R.]

The beautiful paradox of String Theory is that anyone dumb enough to devote 30 years of their life to a non-theory--a theory without postulates, laws, and experimental evidence--will also be dumb enough to defend that theory to the death.


Great!!

Specially when in those 30 years other people have studied things that really work.

Due to failure of string M-theory for explaining physics, some string theorists are this year given talks on "religious" implications of string theory :biggrin:

[brunardot]

Somebody gave you a bad "time line" on this as well.
His Noble Prize was in 1922. Quantum Mechanics didn’t start until 1925/26.


I will stand (or fall) on my basic statement.

(Did you miss the phrase, "he set the groundwork"?

[Juan R.]

ST can predict much with slight adjustments in the theory.

Like for instance: the internal geometry of the "strings."

Unfortunately, its predictions cover the gamut of current enigmas, which theoretical physicists are loathe to discuss in detail. Probably, for fear their house of cards and their grants and sinecures will fall.

On non-technical article cited above I talk of physical predictions.

In a this year preprint, Giddings even admits that he wait that string theory could not finally predict anything.

Some celebrated string theorists as Susskind begin to accept that the theory
cannot explain anything and this has caused some recent trouble. Susskind
adds:


More and more as time goes on, the opponents of the idea admit that
they are simply in a state of depression and desperation.


The famous “cyber-string” theorist Luboš Motl has recently wrote


Some people really seem to be excited by the very fact that they can
embed a relatively convincing framework into string theory whose
conclusion is that we can't predict anything.

Etc

[RandallB]

I will stand (or fall) on my basic statement.

(Did you miss the phrase, "he set the groundwork"?That basic statement was; (His Nobel was a "slap in the face"; as, he didn't believe in QM .....)
The issue in 1911 to 1922 was that relativity was controversial, AND he was German; WW1 political issues between Nations etc. that obviously only got worse and these issues affected the Noble Committee.
Not a slap in the face prize, but a reluctant giving by a committee forced to give due to popular worldwide demand for the man and for SR & GR. So, even if they refused to put SR & GR in the award, that’s what really got him there - wide acceptance of his new "scientific innovation".

Yes, the prize highlighted Light as quantum – setting the groundwork from 1900 for Quantum Physics, not Quantum Mechanics. The groundwork for Quantum Mechanics wasn’t set until 5 years later, thus that QM issue with Einstein did not start until after 1925.

I’ll vote for FALL

[selfAdjoint]

if I remember correctly, they discovered that traditional quantization is not sufficient 5 years ago

You have said this before. Could you gives us a statement or link to clarify it? Is it light cone quantization you are talking about or something else?

[Berislav]

Is it light cone quantization you are talking about or something else? I don't think he's refering to that. He mentioned something about: LPS in Gelfand triplets!!! in post #32.

[brunardot]

That basic statement was; (His Nobel was a "slap in the face"; as, he didn't believe in QM .....)
The issue in 1911 to 1922 was that relativity was controversial, AND he was German; WW1 political issues between Nations etc. that obviously only got worse and these issues affected the Noble Committee.
Not a slap in the face prize, but a reluctant giving by a committee forced to give due to popular worldwide demand for the man and for SR & GR. So, even if they refused to put SR & GR in the award, that’s what really got him there - wide acceptance of his new "scientific innovation".

Yes, the prize highlighted Light as quantum – setting the groundwork from 1900 for Quantum Physics, not Quantum Mechanics. The groundwork for Quantum Mechanics wasn’t set until 5 years later, thus that QM issue with Einstein did not start until after 1925.

I’ll vote for FALL

The intent of intellectual discussion should be that all participants remain upright with a broadened vision.

There was plenty of time before the morning of April 19, 1955 to award a Nobel for SR and GR if the original intent was not a "slap in the face" by the inside academic elite.

Don't forget that for many of these years Einstein detested the cavalierness of Oppenheimer, which was reciprocal if you carefully read "between the lines.".

I raise salient issues throughout this thread and other threads on this forum; yet, everyone attacks minutia and stops/locks large threads without letting me reply; yet, there is a loud "ignore"-ance on the important issues that I raise for discussion.

Am I to understand the salient issues that I raise are accepted without discussion as being correct; and, only the minutia requires tweaking?

Where is sensibility and intellectual inquiry within theoretical physics, which I continue to insist is entirely based on metaphysical concepts of forces and mathematics.

[Juan R.]

People, laymen, young undergraduate students are rather wrong about real status of string theory. One reads articles in popular magazines like Scientific American, news on New York Times or simply read methaphysical books by Kaku, Greene, etc. and one say Woh! string theory is fantastic.

But when one take courses, read articles, and study last advances in the topic, non-commutative strings theory, spacetime foam non critical, M(atrix), TFD-Dp-brane theory, etc., one discovers that:

i) many string theorists are very arrogant.

ii) the theory is not sophisticated in a number of points.

In fact string theory is very trivial in a number of aspects. They ignore the work of others and are working in a theory that others know that is childish. For example, in the 60 Nobel laureate for Chemistry Ilya Prigogine developed novel mathematical thecniques that begin to be used on string theory now!!! But now Prigogine has developed at least three new versions of his old theory. Again string theory is completely outdated, as claimed by many many many specialists.

iii) The "success" of string theory is, on own words of Peter Woit, on public media.

People know string theory but the flaws of theory are always "hidden" on public talks and books. In Elegant Universe you learn about by string theory shows that universe like 4D. But some years after Witten states in an interview that nobody know that (?) and add that string theorists have not reply.

I said during last years that idea of prediction from string theory is completely false. From string theory one can rigorously compute nothing. All claimed exageratios one can derive parts of standard model, or dimensionality of universe, or predicting gravity, or the entropy of Black holes, or obtaining Einstein GR are as follow.

String theory says A = x + y. We know that y = 5.

- Hey guy, what is the experimental value obtained for A?
- 12.

Then x = 7. String theory predicts the correct value A = 12!

Obviously that is not a prediction. And, morever, as denunciated during decades by others theorists, string theory can predict anything and contrary to anything. If experimental value was -12 then they would take x = -17.

I am increasing my personal collections of recent quotes from string theorists. The last is from Maldacena.


I agree with Fredrik that studying the Landscape is very important.
It would be nice to find a smaller number of vacua, so that
predictions are possible.

so that predictions are possible. But 1) nobody has found the correct vacua and cannot predict and 2) last studies show that the number is "infinite", 10^500 or more.

Exceptics of the quote can find it here

http://cosmicvariance.com/2005/07/21/two-cheers-for-string-theory/

[Juan R.]

Is it light cone quantization you are talking about or something else?

I am talking of serious stuff. No Berislav, string theorists are totally outdated. They yet unkown RHS quantization of LPS, that was discussed (if i remember correctly in the Solvay Conference of 1996), i suspect that string theorists will discover that around 2015 or so.

Then, as always they do, will omit all quote to people of conference or in usual literature and call to that string theory. In fact, that is normal unethical phylosophy on that field


string theorists are arrogant enough that whatever comes up in their
research, they will call it string theory.

I was talking of new vector states |Phy>> (which are not Dirac states |Phy>), the new thermal vacuum, the new tilde operation, the new doubled hamiltonian, etc, etc.

On page 10 and 11 of

www.canonicalscience.com/stringcriticism.pdf

you will find more information. After use a simply literature engine and learn that material. I am sorry but i have no time now for search literature for you. I am with the translation of material to new sede of the Center.

Moreover, i am preparing an small, rather revolutionary, article for submision (probably Phys Rev letters). If i am correct, and did no error, then this article shows in a convincing form that string theory is completely wrong.

[marcus]

I am sorry but i have no time now for search literature for you. I am with the translation of material to new sede of the Center.

Moreover, i am preparing an small, rather revolutionary, article for submision (probably Phys Rev letters). If i am correct, and did no error, then this article shows in a convincing form that string theory is completely wrong.

Hello Juan, what direction are you translating: is it for example Spanish to English? I don't understand your phrase "new sede of the Center", my first guess is that you are preparing a new web-page or a new web-site. Did you mean to write "new site for the Center"?

I wish you success in preparing your article. I hope that you are able to post it on arXiv, in preprint form, so that those of us who wish to can have a look.

the main reason for my posting is that I would like to add two papers to the discussion of the fruitfulness (or barrenness) of string research.

these papers suggest that the answer to your original question could be a QUALIFIED NO. One possible position one could take, it seems to me, is to say that NO, the research would not be a waste of time IF it is directed towards constructing a formulation of string which is BACKGROUND INDEPENDENT.

A possible avenue is offered here
http://www.arxiv.org/abs/hep-th/0503140
A quantization of topological M theory
Lee Smolin
20 pages
"A conjecture is made as to how to quantize topological M theory. We study a Hamiltonian decomposition of Hitchin's 7-dimensional action and propose a formulation for it in terms of 13 first class constraints. The theory has 2 degrees of freedom per point, and hence is diffeomorphism invariant, but not strictly speaking topological. The result is argued to be equivalent to Hitchin's formulation. The theory is quantized using loop quantum gravity methods. An orthonormal basis for the diffeomorphism invariant states is given by diffeomorphism classes of networks of two dimensional surfaces in the six dimensional manifold. The hamiltonian constraint is polynomial and can be regulated by methods similar to those used in LQG.
To connect topological M theory to full M theory, a reduction from 11 dimensional supergravity to Hitchin's 7 dimensional theory is proposed. One important conclusion is that the complex and symplectic structures represent non-commuting degrees of freedom. This may have implications for attempts to construct phenomenologies on Calabi-Yau compactifications."

and an argument that a correct theory of quantum gravity must be background independent (together with a discussion of what this means) is given here
http://www.arxiv.org/abs/hep-th/0507235
The case for background independence
Lee Smolin
46 pages
"The aim of this paper is to explain carefully the arguments behind the assertion that the correct quantum theory of gravity must be background independent. We begin by recounting how the debate over whether quantum gravity must be background independent is a continuation of a long-standing argument in the history of physics and philosophy over whether space and time are relational or absolute. This leads to a careful statement of what physicists mean when we speak of background independence. Given this we can characterize the precise sense in which general relativity is a background independent theory. The leading background independent approaches to quantum gravity are then discussed, including causal set models, loop quantum gravity and dynamical triangulations and their main achievements are summarized along with the problems that remain open. Some first attempts to cast string/M theory into a background independent formulation are also mentioned.
The relational/absolute debate has implications also for other issues such as unification and how the parameters of the standard models of physics and cosmology are to be explained. The recent issues concerning the string theory landscape are reviewed and it is argued that they can only be resolved within the context of a background independent formulation. Finally, we review some recent proposals to make quantum theory more relational."

[Juan R.]

Hello Juan, what direction are you translating: is it for example Spanish to English? I don't understand your phrase "new sede of the Center", my first guess is that you are preparing a new web-page or a new web-site. Did you mean to write "new site for the Center"?

I wish you success in preparing your article. I hope that you are able to post it on arXiv, in preprint form, so that those of us who wish to can have a look.

the main reason for my posting is that I would like to add two papers to the discussion of the fruitfulness (or barrenness) of string research.

these papers suggest that the answer to your original question could be a QUALIFIED NO. One possible position one could take, it seems to me, is to say that NO, the research would not be a waste of time IF it is directed towards constructing a formulation of string which is BACKGROUND INDEPENDENT.

A possible avenue is offered here
http://www.arxiv.org/abs/hep-th/0503140
A quantization of topological M theory
Lee Smolin
20 pages
"A conjecture is made as to how to quantize topological M theory. We study a Hamiltonian decomposition of Hitchin's 7-dimensional action and propose a formulation for it in terms of 13 first class constraints. The theory has 2 degrees of freedom per point, and hence is diffeomorphism invariant, but not strictly speaking topological. The result is argued to be equivalent to Hitchin's formulation. The theory is quantized using loop quantum gravity methods. An orthonormal basis for the diffeomorphism invariant states is given by diffeomorphism classes of networks of two dimensional surfaces in the six dimensional manifold. The hamiltonian constraint is polynomial and can be regulated by methods similar to those used in LQG.
To connect topological M theory to full M theory, a reduction from 11 dimensional supergravity to Hitchin's 7 dimensional theory is proposed. One important conclusion is that the complex and symplectic structures represent non-commuting degrees of freedom. This may have implications for attempts to construct phenomenologies on Calabi-Yau compactifications."

and an argument that a correct theory of quantum gravity must be background independent (together with a discussion of what this means) is given here
http://www.arxiv.org/abs/hep-th/0507235
The case for background independence
Lee Smolin
46 pages
"The aim of this paper is to explain carefully the arguments behind the assertion that the correct quantum theory of gravity must be background independent. We begin by recounting how the debate over whether quantum gravity must be background independent is a continuation of a long-standing argument in the history of physics and philosophy over whether space and time are relational or absolute. This leads to a careful statement of what physicists mean when we speak of background independence. Given this we can characterize the precise sense in which general relativity is a background independent theory. The leading background independent approaches to quantum gravity are then discussed, including causal set models, loop quantum gravity and dynamical triangulations and their main achievements are summarized along with the problems that remain open. Some first attempts to cast string/M theory into a background independent formulation are also mentioned.
The relational/absolute debate has implications also for other issues such as unification and how the parameters of the standard models of physics and cosmology are to be explained. The recent issues concerning the string theory landscape are reviewed and it is argued that they can only be resolved within the context of a background independent formulation. Finally, we review some recent proposals to make quantum theory more relational."

Hello Marcus, thanks by your proffesional advice!

First i would apologize by my lasts errors on posts. Since that it is so important for you, let me to say the trick "translating -> moving" and "sede -> 'office'".

No, I do not post it on ArXiv, it was submited.

Let me be highly sceptic of the "QUALIFIED NO".

Even if you obtain a BACKGROUND INDEPENDENT formulation of string theory the reply continues to be not NO.

Thanks by articles, but are not of utility for me. M theory is waste of time and relationism does not work (in fact, it is wrong).

[Berislav]

First of all let my apologize for not responding sooner. I've been away and didn't have access to the internet.

You appears rather confounded, I recomend to you The book “Hiding in the Mirror: The Mysterious Allure of Extra Dimensions,” to be published this year by Krauss. Thank you, but I would prefer a technical account of string theory's suppossed fatal flaws. Pop-science books would make me even more confounded.

You begin from a 4D formulation (initially people did not leave dimensionality unknown) but quantizing the open bosonic string, you obtain the spectral decomposition for the first excited state.... etc. Yes. I think that you will find exactly that after applying the spectral theorem to the operator I mentioned. And like I said I agree with you that this doesn't seem elegant.

I wish you success in preparing your article. I too wish you success, Juan R.

[Telos]

There are many different pursuits within string theory that might be a waste of time, but the basic ideas certainly are not.

But string theory has done something WORSE than be a waste of time. It has been the poster child for a harmful and misleading crusade against young people - that physicists are near the end of their journey and we don't need anymore help thank you very much. Championing string theory via the Elegant Universe to the public while in its current form was shameful and irresponsible.

[marcus]

There are many different pursuits within string theory that might be a waste of time, but the basic ideas certainly are not.

But string theory has done something WORSE than be a waste of time. It has been the poster child for a harmful and misleading crusade against young people - that physicists are near the end of their journey and we don't need anymore help thank you very much. Championing string theory via the Elegant Universe to the public while in its current form was shameful and irresponsible.

that's an interesting point of view, Telos. basically you are disapproving of the hype to the public, and not the internal hype and self-indulgence (among initiates) or the over-investment of brain-time. I think quite a few people would agree with you, can't say that I would entirely.

[Juan R.]

Thank you, but I would prefer a technical account of string theory's suppossed fatal flaws. Pop-science books would make me even more confounded.


On that book you will find references to modern work.

[marcus]

You appear rather confounded, I recommend to you The book “Hiding in the Mirror: The Mysterious Allure of Extra Dimensions,” to be published this year by Krauss.

On that book you will find references to modern work.

Juan you have made me curious. How do you know? Have you seen a draft copy, or some preprint sections, of Larry Krauss' book? Please share what information you have about the book.

[Juan R.]

There are many different pursuits within string theory that might be a waste of time, but the basic ideas certainly are not.

The basic ideas also were a waste of time. For instance:

- the idea that a single parameter could be used for predicting all (False).
- The idea of unidimensional strings explaining all (False). The hundred of elementary particles would be reduced to a single string vibrating in different modes (False). M-theory is many times more complex that QFT, with all kind of unobserved objects from pointlike particles (D0) to nine-dimensional objects, passing by membranes, etc.
- The idea of that field theory pointlike behavior was "stupid", a heavy approximation to elegant math of extended objects (False).
- The idea of quantum gravitation WAS a spin-2 perturbation on a classical flat metric (False).
- Etc.

For example, i remain atonished that string theorists have a special facility for hiddeing to public that the formulation of M-theory known is a quantum mechanics of pointlike particles: the D0-branes. The old concept of string -as other extended objects of old theory- arises like an approximation.

[marcus]

The basic ideas also were a waste of time. For instance:



Dear Juan, I do wish you didn't SOUND so opinionated. Sure we probably all are opinionated in some ways but we dont express it quite so categorically, and the conversation benefits, I think, from that restraint. But maybe that is just your STYLE and I shouldn't quibble about stylistic oddities.

By the way thank you for informing us about Krauss book, scheduled to come out in just two months (October 20)!


You appear rather confounded, I recommend to you The book “Hiding in the Mirror: The Mysterious Allure of Extra Dimensions,” to be published this year by Krauss.

On that book you will find references to modern work.

I didn't know about this book until you mentioned it just now. I found this on google

http://www.amazon.com/exec/obidos/tg/detail/-/0670033952/104-0053556-9027905?v=glance

[marcus]

My goodness!
Following Juan's pointer I went to Amazon and found Krauss book ("the allure of hidden dimensions, from Plato to String Theory") due out 20 october, but I also came across this!

http://www.amazon.co.uk/exec/obidos/ASIN/0465078389/qid=1124203447/sr=1-10/ref=sr_1_2_10/202-7931077-6960601

All Strung Out

by Lee Smolin!

For sale at Amazon.co.UK, the price is 19.15 sterling.
Apparently the publisher Basic Books brought it out on 3 July.

[Telos]

Juan, I do not think it is a waste of time to show that something is false.

Interesting book, though!

[Juan R.]

Juan you have made me curious. How do you know? Have you seen a draft copy, or some preprint sections, of Larry Krauss' book? Please share what information you have about the book.

No i did not see the book. I was informed about him talking with a friend. Moreover, it appears that its publication data has been delayed but i am not sure.

[Juan R.]

Dear Juan, I do wish you didn't SOUND so opinionated. Sure we probably all are opinionated in some ways but we dont express it quite so categorically, and the conversation benefits, I think, from that restraint. But maybe that is just your STYLE and I shouldn't quibble about stylistic oddities.


Marcus, i understand that talking about quantum gravity is often a heated debate. But you would appreciate my evaluation of the theory. I am not alone here. Many other scientists have said similar words about string “theory” and lot of them assure like I am doing that string theory is a waste of time, including a previous student that began a PhD on string theory and abandoned the fields because considered that was a waste of time.

You can be sceptic of my evaluation of the theory (that is not a problem for me). But my evaluation is, exactly, that string theory is a waste of time (and money). I could search other words for you but the message would be the same.

You are well-versed Marcus and probably know the history of Albert Einstein, who failed in his search to find a unified theory of forces in the universe, spending the last three decades of his life isolated from the scientific community.

Glashow (the Nobel laureate) said,


So when one person spends 30 years, it's a waste, but when thousands waste 20 years in modern day, they celebrate with champagne. I find that curious.

Einstein unified field theory was a waste of time because Einstein did not follow the scientific method (Einstein ignored experimental data on nuclear forces for instance).

String theory is completely outdated. It is based in concepts and ideas of the 90s. To work in it is a waste of time (and money).

[marcus]

Juan, I do not think it is a waste of time to show that something is false.

Interesting book, though!

I see the book Juan mentioned (that amazon says is due out in October) is by the same physicist/cosmologist/popular author who wrote "The Physics of Star Trek" and "Fear of Phyics: a Guide to the Perplexed".

Telos, you are definitely on to something about time spent drawing testable conclusions from a theory so that it may be shown false.

[marcus]

You can be sceptic of my evaluation of the theory (that is not a problem for me). But my evaluation is, exactly, that string theory is a waste of time (and money). I could search other words for you but the message would be the same.
...

I am skeptical of the broad way the evaluation is stated. There are several things to say. One is that your opinion is shared (in a qualified way) by a growing number of physicists, for reasons that were mentioned in this earlier PF thread:
http://www.physicsforums.com/showthread.php?t=80760

In this thread, which Ratzinger started in June 2005, some knowledgeable PF people like Haelfix, selfAdjoint, Ohwilleke, concisely reported some reasons why there has been a decline, over the past 3 years or so, in interest and popularity of string research.

Increasing worry and pessimism among string researchers was reflected in the Toronto discussion video.
http://www.physicsforums.com/showthread.php?t=84585
One encounters expressions of disillusion among graduate students---some of whom are changing fields---and symptomatic efforts being made by string-loyal bloggers (such as Motl and Distler) to shore up morale among the graduate students.

We also see some statistical indications of the decline in string interest, popularity, optimism. One can always argue about how to interpret the various statistical measures, however.

I must say that observing this string "downsizing" going on has increased my respect for the honesty and courage of certain researchers such as Andy Strominger. He made an excellent two minute statement in the Toronto discussion at time 1:28:20
It put me in mind of a story in the Bible where a general tells his soldiers that anyone who wants to can go home, and about half of them leave (this is called "downsizing"), then the remaining ones go on to win the battle.

Anyway Juan, I will try to say what I think about your message that string theory is a waste of time.

[marcus]

...Anyway Juan, I will try to say what I think about your message that string theory is a waste of time.

1. it doesnt mean anything unless you say FOR WHOM it is a waste of time.

2. increasing numbers of people seem to be deciding that FOR THEM it is a waste of time, and so they are getting out of the field, or they are not writing so many research papers as they did. (However on arxiv I see a growing number of string papers by people at Beijing Normal and other large Chinese universities. These people do not think string is a waste of time for them and they are responsible for an increasing fraction of the research postings.)

3. your statement does not have a clear meaning unless you specify a waste of time AS WHAT. I think a lot of people would agree that string theory can lead to ideas and results that are interesting AS MATHEMATICS.

4. your statement would not apply to a mathematically gifted young person who goes into string and discovers something interesting and valuable AS MATHEMATICS. You cannot say that such a person is wasting their time!
What gives mathematics intrinsic WORTH is the interest it evokes from other mathematicians. It does not need to be a fundamental testable model of nature.

5. however your message, suitably qualified and restricted, is a very helpful one to have expressed---and voicing it actually DOES STRING THEORISTS A FAVOR by increasing the pressure on them to arrive at a nonperturbative background independent formulation that makes falsifiable predictions. This is the only way to be sure that string theorizing is not a waste of time AS PHYSICS.

[Telos]

Telos, you are definitely on to something about time spent drawing testable conclusions from a theory so that it may be shown false.

Wish I could say I thought of it myself!

[marcus]

Wish I could say I thought of it myself!

the important ideas are like that. you only pass them along, instead of originating them

[Juan R.]

As said, I do not think that the decline of string research program is just temporary one. In the past, there were difficulties but now people is seeing that each year original objectives of string theory are far, and far, and farther. String theory history looks like a divergent asymptotic series.


I must say that observing this string "downsizing" going on has increased my respect for the honesty and courage of certain researchers such as Andy Strominger.

Said I the contrary? I am against half-true that many string physicists popularized as the new standard in scientific communication. I am also against arrogance typical of many string theorists (of course not all).

Now, let me reply your very interesting comments.


1. it doesnt mean anything unless you say FOR WHOM it is a waste of time.

I disagree; I provided abundant data in all aspects of the theory (geometry, hidden dimensions pointlike behavior, spectral decomposition, relativity, arrow of time, reductionism, etc.) and already explained that I was talking of string theory like a TOE on post #5.

As said by Nobel laureate P. Anderson this year, string theory is a futile exercise as physics. I substituted “futile exercise” by “waste of time” but my evaluation of string theory continues being correct.

I would state that string theorists provide none serious argument why we would believe on string theory, only bold statements like "it is the most promising way" or wrong claims like "is the only was to quantum gravity". I see an injustice here with people that are not string believers.


2. increasing numbers of people seem to be deciding that FOR THEM it is a waste of time, and so they are getting out of the field, or they are not writing so many research papers as they did. (However on arxiv I see a growing number of string papers by people at Beijing Normal and other large Chinese universities. These people do not think string is a waste of time for them and they are responsible for an increasing fraction of the research postings.)

I am sorry to say this Marcus but this kind of argument is childish. A theory (or hypothesis) is not a “futile exercise as physics” on function of the number of papers or researchers working in it. Or would I remember to you the number of papers in early investigation of perturbative quantum gravity until was shown that QGR was nonrenormalizable on independence of parameter of expansion taken. All previous work in dozens of attempts to quantize GR directly were a waste of time.



3. your statement does not have a clear meaning unless you specify a waste of time AS WHAT. I think a lot of people would agree that string theory can lead to ideas and results that are interesting AS MATHEMATICS.

The premise is obvious when one know why was formulated string theory. String theory is a “theory” of physics. Its main objectives are unification of forces quantizing gravity, systematization of the standard model, and possibly the explanation of some cosmological mysterious.

Has string theory been interesting on mathematical topics? Of course, but that does not justify the hype around it and its study on physics dept. Moreover, let me say that the impact of string theory in the whole of mathematics is not so huge, at least, it is not more important (by orders of magnitude) that impact of some field theoretical techniques. For example, contrary to popular belief, Fields Medal awarded to Witten was not by the application of pure string theory methods to math, most of mathematical work of Witten was from field theory. Atiyah, who is many times more smart and versed that i in these topics, affirms that string theory has had an impact on mathematics which has been really quite extraordinary. Well, he said that in a popular interview. However, far from popular claims, I see not radical advances on mathematics as provided by the own Atiyah on "index theorems" (theory of quantum operators in quantum field theory).


4. your statement would not apply to a mathematically gifted young person who goes into string and discovers something interesting and valuable AS MATHEMATICS. You cannot say that such a person is wasting their time!
What gives mathematics intrinsic WORTH is the interest it evokes from other mathematicians. It does not need to be a fundamental testable model of nature.

Already replied. That young mathematician, if interested in string “theory”, would focus on the mathematical branches below string physical theory, including non-commutative geometry, G2 manifolds, K theory, topology, and news branches of analyses and algebra, etc. Of course, with an eye in the “physical” stuff.


5. however your message, suitably qualified and restricted, is a very helpful one to have expressed---and voicing it actually DOES STRING THEORISTS A FAVOR by increasing the pressure on them to arrive at a nonperturbative background independent formulation that makes falsifiable predictions. This is the only way to be sure that string theorizing is not a waste of time AS PHYSICS.

This is a very, very astonishing simplification of the problem. Background independence is not the magical cure to all problems of string theory. Even if one day a background independent version of string theory is achieved (I doubt), string theory will continue to be a waste of time like a TOE. Moreover, it will continue to be as non-predictive like is now.

Do not forget that LQG is claimed background independent whereas continue to be an “inefficient” approach to quantum gravity. In fact, there is no possibility for obtaining a consistent classical limit converging to GR after of 40 years from Hamiltonina gravity: geometrodynamics, Astherkar QGR, LQG, etc.

Smolin, as others loop theoreticians, assumes that relationism is correct, but it is not as already said. The idea of that causality becomes a fuzzy notion because of fluctuation of light cones is completely wrong.

[lightcone]

i am sure strings are going to disappear and first sign of this is the idea os landscape of vacuua. it is such a comic trash that during seminar you feel like quiting physics because such are the things promoted as future directions.

but stringers cannot fool th world much long and more so because some of them are serious researchers with a conscience still alive.

plase read freeman dyson: disturbing the universe and you will know hy string theory qualifies as a failure.

The problem of delay in this being branded a failure is obvious, INERTIA. there are too many researchers persuing it who are trained as stringers unlike the masters who were all high energy physicists. S now we have this young generation of ignorant people who doesnt even know where to find mistake to stop doing it since they simply do not know physics. It is just poor quality mathematics.

[marcus]

i am sure strings are going to disappear and first sign of this is the idea os landscape of vacuua. it is such a comic trash that during seminar you feel like quiting physics because such are the things promoted as future directions.

but stringers cannot fool th world much long and more so because some of them are serious researchers with a conscience still alive.
...

I agree with the respect you show for serious and principled researchers
"...serious researchers with a conscience..."

Public support for physics ultimately depends on the trust that nonspecialists have in the self-critical, "self-policing" ability of theorists to remain engaged with empirical reality. So your perception that there are some who are not indulging in a mathematical escapade is very important.

[marcus]

"inefficient"
CDT path integral has not given any signs of being an inefficient approach to quantum gravity, and to the extent that one can compare the two rather different approaches I would say that it is MORE background independent than canonical LQG.

Among tested, well-established theories, General Relativity is the most background independent model we have. When quantizing Gen Rel, it is obvious to try to preserve the B.I. feature if one can. The comparative success or failure of various attempts to do this is not relevant to the validity of the effort.

With both String and canonical Loop experiencing difficulties, one sees that it is actually the most background independent approach that is currently making the most progress.

[RandallB]

Marcus
On Strings I feel it’s future may well becoming a waste land. But I believe it has been very valuable in identifying the 11 dimensions issue. Lack of progress indicates that this idea is likely just wrong. But ANY future theory that proves 11 D as wrong, should also be able to explain why the 11 D issue appeared to be viable at all. Just this additional ‘test’ of future theories, I think that can be worth quite a bit.

Also, You mentioned something else I could use a little help on “how I think”
Among tested, well-established theories, General Relativity is the most background independent model we have.Having never really put it into words before, but I’d though of GM as background dependent. That is with the “warping” of space time was still a manipulation of a background dependent interpretation of space and time.

Your comment tells me I need to Fine Tune my thinking a bit. Does the following make sense:

SR Special Relativity - background dependent
Works on a ‘dependant’ background of space and time in a classical manner. Just the Newton formulas were inadequate and the measures of space or distance over time need to be understood by the better formulas provided by relativity.

GR General Relativity - background independent
The use of a warping of time and space into “space/time’ to understand gravity, releases us from a background dependent measure. That is the physics we see, relativity included, is not dependent on any background traceable measure in either distance. But rather only dependent on the “relationships” between physics events that cannot be tied down to a measurable background reference of space and time.

A fine point but seems an important one I’d not fully recognized.

In a similar fashion :

Quantum Theory - background dependent
Quantized the minimum amount of energy to be found in light “packets” now photons. And set minimum size of change in measure we could expect to ever make in both time and distance (space). Natural limitations associated with this made near impossible to make significant progress until.

Quantum Mechanics - background independent
Instead of “warping” the relationship of time and space, used the uncertainty principal to allow measure and predictions at the quantum level to become understandable.
Thus one way to explain the inability of combining the physics of QM and GR even though they are both “background independent” is that they arrived at their independence in dramatically different forms (warping vs., probabilities) that we so far have been unable to interrelate.
(I'd previously considered not being able to combine the two as a dependent vs. independent issue)

Is this a reasonable tune up to my thinking?
Let me know if I’ve gone off track on the “background” issue as it is a bit new to me.

Also are there any other “well-established theories” that arrive at their background independence though some other manner than GR or QM? I’m assuming that most all, like M-Strings, have their foundation in QM.

Thanks
RB

[marcus]

Marcus
On Strings I feel it’s future may well becoming a waste land. But I believe it has been very valuable in identifying the 11 dimensions issue. Lack of progress indicates that this idea is likely just wrong. But ANY future theory that proves 11 D as wrong, should also be able to explain why the 11 D issue appeared to be viable at all. Just this additional ‘test’ of future theories, I think that can be worth quite a bit.

Also, You mentioned something else I could use a little help on “how I think”

Among tested, well-established theories, General Relativity is the most background independent model we have.

Having never really put it into words before, but I’d though of GM as background dependent. That is with the “warping” of space time was still a manipulation of a background dependent interpretation of space and time.

Your comment tells me I need to Fine Tune my thinking a bit...

this is a sign we need a link to basic Differential Geometry primer where the idea of a "differentiable manifold" (often a "smooth manifold") is defined

does anyone have an Intro to D.G. or Intro to Manifolds link?

Randall there are two abstr. math. ideas you need that are actually very simple and easy to get-----Manifold and Metric-on-the-manifold.

For 150 years the fundamental paradigm for a continuum that everyone uses is a Manifold (defined by Riemann around 1850).

the most common meaning of B.I. is you start with a Manifold without a metric.

in a B.D. theory you start with a manifold and give yourself a metric on it to start with as well

have to go back later

[marcus]

Randall it is soooooo simple. I wish you would take a moment and think it over and come back and say honestly that you understand perfectly clear as day.

the reason we accumulate math concepts over the decades is ultimately MENTAL ECONOMY. they make thinking more efficient. and this is a case

the fundamental object in D.G. is the manifold which corresponds to the idea of a continuum without geometry. it is a blob that has coordinate functions defined on it
(local charts that are smooth and compat where they overlap)
but does not have any dingus or appliance that can tell you the distance between two points

because it has coordinates, at any point on the manifold you can explore all the possible directions in which you can take the derivative!!!!!!
All the possible DEE-EXES, and when you think calmly and patiently about this for a while you realize that this collection of all possible dee-exes IS the tangent space. it captures the essence of what we want the tangentspace at any give point to do for us. and it is intrinsic (defined without reference to anything surrounding the manifold)

this is a fundamental Idea of Western Civilization, like the freedom of the individual and the rule of law etc. this is the Idea of the Continuum which has been standard for 150 years

It is INTRINSIC. it doesnt have to be embedded in any larger space for you to know its tangent space at each point and be able to do calculus etc, and it STILL HAS NO IDEA OF GEOMETRY built in.

to do geometry you introduce a "metric" gizmo which is a bi-linear dingus defined on the tangent space at every point blah blah
and once you have a metric g(m) defined at every point m of the manifold then you can compute distances, angles, areas, volumes etc.

The most common meaning of B.I. is that you start with a manifold without a metric.

In Gen Rel you start with a 4D spacetime manifold and some matter and you set up this equation and Presto! you PULL THE METRIC OUT OF THE HAT! (EDIT: selfAdjoint objects to the wording. I mean that you solve for the gravitational field, which is the metric. more discussion of details of this in later posts...)

the metric, or geometry, can be totally freeform and it is determined dynamically by interaction with matter through the equation of the model.

This is VERY DIFFERENT FROM perturbative STRING THEORY where they start with a manifold that already has a prior-chosen metric defined on it.
Having a prior chosen metric lets you define the twangy equation by which the little thangs be vibratin'. Without that prior metric you got nothing to start with, stringywise.

[selfAdjoint]

In Gen Rel you start with a 4D spacetime manifold and some matter and you set up this equation and Presto! you PULL THE METRIC OUT OF THE HAT!


That's not quite right. You don't need the matter, it's strictly geometry. You don't pull the metric out of a hat, you introduce it as a general symmetric quadratic form, the coefficients of which turn out to form form a symmetric rank two tensor. This is just a generalization of Pythagoras's (or Lorentz's) rule. You can then express the very special connection (Levi-Civita) in terms of derivatives of the metric tensor, and from the connection coefficients you define the curvature tensor (Riemann-Christoffel tensor). In Riemannian geometry the metric comes before everything else.

[marcus]

the fundamental string stumbling block is that in over 20 years nobody has succeeded in doing string without prior-choosing a metric

but to truly do Gen Rel you cannot choose the metric because geometry is a dynamic thing that comes out of the model----the geometry of the manifold is gravity and you do not stipulate it in advance

in standard vintage Gen Rel the gravitational field IS the metric g(m)
and it is what you solve for
it is the unknown distance function that the Einstein equation is about.

this is the basic obstacle that string research has always been up against

----------------------------

an amusing behavior of string theorists, which you can see recently over at the Coffee Table blog, is that whenever anybody reminds them of this major roadblock they immediately start talking defensively.

they dont stop, take a breath, and say "Yes that is right, we really need to put some effort into a nonperturbative, background independent formulation!"

Instead, they start making excuses and talking about the INADEQUACIES OF LOOP which is really irrelevant. They get into this complicated distracting discussion about how String "really" doesnt need to be B.I. and how it "really" is B.I. (if you define B.I. right) and how Loop is not "really" B.I. (if you define B.I. a certain way), and sometimes they start complaining that it isnt NICE of anyone to point out this defect because it might give non-experts the idea there was something wrong.

We just had an example of this at a couple of stringy blogs this month when folks were reacting to Smolin's paper "The Case for Background Independence". That paper was friendly advice, and the reaction was defensive, as if it were an attack. Check this out:

http://golem.ph.utexas.edu/string/archives/000621.html

I am waiting for someone like Andy Stromiger (who I suspect has guts) to come out with a clear statement on this and say "yes we need a B.I. formulation that we can really calculate with, and we ought to give his high priority and work on it, and we can do it"

[marcus]

... In Riemannian geometry the metric comes before everything else.

I agree totally. what I mean by pulling the metric out of a hat is that you SOLVE for the metric.

all the terms in the equation are defined based on the metric, so the metric comes before all that other stuff---curvature tensor like you say.

the idea I am trying to get across is somewhat simpler and more basic:

the gravitational field IS the metric
you don't start off knowing the metric
you SOLVE for it


exactly as you say, part of solving for the metric is going through stuff like the Riemann-Christophel tensor whose definition is based on the metric

thanks for adding some clarification, selfAdjoint.
would be great to have some standard links to basic D.G.
and a standard exposition of what B.I. is about
I appreciate your help

[marcus]

my idea of a really background independent nonperturbative approach to QG is Loll triangulations path integral. I will get some links

http://arxiv.org/hep-th/0404156

Emergence of a 4D World from Causal Quantum Gravity

http://arxiv.org/hep-th/0505154

Reconstructing the Universe

http://arxiv.org/hep-th/0505113

Spectral Dimension of the Universe

http://arxiv.org/hep-th/0411152

Semiclassical Universe from First Principles

more here
http://arxiv.org/find/grp_physics/1/au:+Loll/0/1/0/all/0/1

Eventually I hope to see some string theorists implement a version of string theory on the Loll CDT spacetime as a foundation. (rather than on their usual kind of manifold)

The original work in Dynamical Triangulations in early 1990s (which led to Loll CDT path integral in 1998) was actually an attempt by Ambjorn to find a NONPERTURBATIVE FORMULATION OF STRING---he thought he was doing matrix theory and he ended up with the CDT path integral.

One of Smolin's points is that a head-on effort to make string non-perturbative, or background independent, is likely to be fruitful (as it has been in the past) whether or not one finds a passage to the original goal

Another is that by throwing out assumptions one makes a theory more predictive---the less you assume the harder it is to build and the more restrictive it is---so the more falsifiable. So he proposes making the theory less dependent on comfortable background assumptions as a way out of the landscape confusion.

[Hurkyl]

because it has coordinates, at any point on the manifold you can explore all the possible directions in which you can take the derivative!!!!!! ...

I feel the need to make a slight correction: you need a differentiable manifold to do this extra stuff!


Some manifolds are just so miserable that there is no way to equip them with a differentiable structure. Thus, no derivatives for you!

Some other manifolds are too accomodating: there are many fundamentally different ways to equip them with a differentiable structure! So you have to select which one you like before using derivatives!

[marcus]

I feel the need to make a slight correction: you need a differentiable manifold to do this extra stuff!


Some manifolds are just so miserable that there is no way to equip them with a differentiable structure. Thus, no derivatives for you!

Some other manifolds are too accomodating: there are many fundamentally different ways to equip them with a differentiable structure! So you have to select which one you like before using derivatives!

You are absolutely right. I mean a differentiable manifold every time I say manifold. It just gets tiresome to type it after I have said it once.

Personally I like C-infinity, but at least C-one!

[Mike2]

The most common meaning of B.I. is that you start with a manifold without a metric.
...
the metric, or geometry, can be totally freeform and it is determined dynamically by interaction with matter through the equation of the model.
Interesting! If there are no particles, then it becomes impossible to say how far apart things are; there are no reference points to say how far apart things are with respect to. It becomes completely meaningless to say how far apart things are if there are no things between which to measure. So it seems, no particles, no metric. The laws of physics before particles seems to be totally invariant with whatever metric one might impose or imagine. Particles seem to arise with the emergence of a metric. The particle characteristics derive from various kinds of symmetry which are only describable with a metric. So... no metric, no particles.

So the question becomes, how did particle and/or the metric come into existence to begin with? How was the initial total symmetry broken? Did the metric have to start out with zero distance between particles? I'm sure without a metric to start with, we have to rely on topological characteristics to answer how a metric came to be.

[Hurkyl]

At least once you have a C1 manifold, there's a unique way to turn it into a C&infin; manifold. :smile:

[Hurkyl]

Interesting! If there are no particles, then it becomes impossible to say how how far apart things are; there are no reference points to say how far apart things are with respect to.

The presence or lack of particles has no bearing upon whether the metric exists.

What you're touching upon is the problem of measurement.


The laws of physics before particles seems to be totally invariant with whatever metric one might impose or imagine.

Yes and no... the equations themselves are invariant, but they often take the metric as a parameter.


In fact, the metric isn't even fundamental -- General Relativity can be reformulated without any reference to a metric. (At least if I understand correctly)

[Mike2]

The presence or lack of particles has no bearing upon whether the metric exists.

I'm not sure what epoc of cosmology you are referring to when there was curved spacetime before particles existed.

As I recall, it requires matter to produce curved space in Einstein's eq.

Perhaps you are refering to massive particles only?

I'm trying to imagine what measure one would use when there are no objects to measure with respect to, or no center, or no edge. It would seem one measure would be just as effective an any other.

[marcus]

-- General Relativity can be reformulated without any reference to a metric. (At least if I understand correctly)

you understand correctly. I would just say that I've never heard anyone say that the metric formulation is any less fundamental than some other formulation (e.g. Sen-Ashtekar variables)

I think one can argue that neither is more fundamental they are just different ways. Maybe other people have differing views on this.

Thiemann's postdoc Bianca Dittrich (one of the strongest LQG researchers now) just posted a paper in which she chose to work with the metric instead of the connection formulation (Ashtekar style). Several others have made this choice also in some if not all of their recent papers (Reuter, Husain, Winkler, Modesto). So the metric continues in use in quantum gravity and there seems no clear choice for the moment.

Dittrich's paper was
http://www.arxiv.org/abs/gr-qc/0507106
Partial and Complete Observables for Canonical General Relativity
B. Dittrich
33 pages
"In this work we will consider the concepts of partial and complete observables for canonical general relativity. These concepts provide a method to calculate Dirac observables. The central result of this work is that one can compute Dirac observables for general relativity by dealing with just one constraint. For this we have to introduce spatial diffeomorphism invariant Hamiltonian constraints. It will turn out that these can be made to be Abelian. Furthermore the methods outlined here provide a connection between observables in the space--time picture, i.e. quantities invariant under space--time diffeomorphisms, and Dirac observables in the canonical picture."

[CarlB]

All the possible DEE-EXES, and when you think calmly and patiently about this for a while you realize that this collection of all possible dee-exes IS the tangent space. it captures the essence of what we want the tangentspace at any give point to do for us. and it is intrinsic (defined without reference to anything surrounding the manifold)

this is a fundamental Idea of Western Civilization, like the freedom of the individual and the rule of law etc. this is the Idea of the Continuum which has been standard for 150 years.
...
This is VERY DIFFERENT FROM perturbative STRING THEORY where they start with a manifold that already has a prior-chosen metric defined on it.

Having a prior chosen metric lets you define the twangy equation by which the little thangs be vibratin'. Without that prior metric you got nothing to start with, stringywise.

I think that the problem with defining geometry through the tangent vectors of the underlying manifold is the unusual symmetry breaking observed in the standard model. The conventional solution to this problem is to retain the assumption that space-time possesses, for example, left / right symmetry, but that the vacuum does not.

However, if you build up geometry from the tangent spaces of the points of the manifold, then you can arrange for the symmetry breaking to occur in space-time itself. This is a modification of the ideas of David Hestenes with the Geometric Algebra.

The GA takes the tangent vectors of the manifold and uses them as the generators of a Clifford algebra. The signature of the Clifford algebra is typically taken to be (-+++) or (+---); this is a feature that doesn't show up in the manifold but has to be added.

Anyway, if you begin with the GA, you end up with same symmetry that the usual version of space-time possesses, but it is possible to generalize the relationship between the tangent vectors and the Clifford algebra in a manner that reproduces the symmetry breaking that distinguishes between the symmetry of space-time and the symmetry of the observed vacuum.

Carl

[marcus]

... GA takes the tangent vectors of the manifold and uses them as the generators of a Clifford algebra. The signature of the Clifford algebra is typically taken to be (-+++) or (+---); this is a feature that doesn't show up in the manifold but has to be added.
...

Hi Carl, the original question that Randall asked was about background independence

what I want to focus attention on here is WHAT CAN YOU DO WITH NO PRIOR METRIC?

so there is no bilinear form on the tangent space at a point.

(when you talk about "signature" you are assuming some bilinear form on the tangent space, I want to stop well before that point and look around)

the B.I. viewpoint is all you have is the manifold----a continuum without prior assumed geometry----and then the gravitational field arises dynamically AS the geometry.

So we are going in opposite directions here: you are looking for more prior structure (which could be mathematically very nifty, like Clifford algebras) and I want to illustrate (in case anyone is interested in Background Independence) what it looks like with LESS prior structure.

The various non-string QG approaches tend to be built on a manifold WITHOUT metric, or to have even less structure.

For example in Loll CDT Triangulations YOU DON'T EVEN ASSUME THAT THE CONTINUUM IS A MANIFOLD. You just approximate it, in a certain sense, by manifolds. And of course there is no prior metric and no Clifford algebra or any of that stuff.

Background Independent means "no frills"
you try to assume as little as possible to get started with
and the surprise is when something we associate with familiar macroscopic space EMERGES.

Like 4D dimensionality, as reported here:
http://arxiv.org/hep-th/0404156

this is one of the articles I gave links to some 8 or 9 posts back. Maybe I should bring up that list of links.

[marcus]

It is really remarkable, Carl. They dont even put in that space is supposed to be 4D and it COMES OUT THAT WAY at macroscopic scale, although at very short range the spectral dimension measured by diffusion processes comes out less. Carl I think you have read some CDT--weren't we discussing that in the "Introduction" thread? But in case anyone else is reading along with us I will bring up that list of CDT links from a few posts back

my idea of a really background independent nonperturbative approach to QG is Loll triangulations path integral. I will get some links

http://arxiv.org/hep-th/0404156

Emergence of a 4D World from Causal Quantum Gravity

http://arxiv.org/hep-th/0505154

Reconstructing the Universe

http://arxiv.org/hep-th/0505113

Spectral Dimension of the Universe

http://arxiv.org/hep-th/0411152

Semiclassical Universe from First Principles

more here
http://arxiv.org/find/grp_physics/1/au:+Loll/0/1/0/all/0/1

Eventually I hope to see some string theorists implement a version of string theory on the Loll CDT spacetime as a foundation. (rather than on their usual kind of manifold)

.

[Chronos]

Ouch. I am amazed that background independence is somehow irrelevant. It seems a difficult and awkward position from which to propose a 'theory of everything'.

[CarlB]

Hi Carl, the original question that Randall asked was about background independence

what I want to focus attention on here is WHAT CAN YOU DO WITH NO PRIOR METRIC?

so there is no bilinear form on the tangent space at a point.

(when you talk about "signature" you are assuming some bilinear form on the tangent space, I want to stop well before that point and look around).

When you require a mixed signature, I agree with you, that is, I agree that one must have something in addition to the manifold itself.

However, it is also possible to treat time as an independent variable. That is, one can treat time as separate from the geometry of space. If you do this, then the signature becomes (++++), and you don't need to specify a bilinear form. Instead, one defines the tangent vectors as velocity vectors. In other words, the metric is a result of the continua having a characteristic velocity. This is a classical way of treating space and time, that is separately.

Having read the links you've provided, I must say that I am singularly unimpressed with their lack of assumptions about the physical world. I saw no "emergence of a 4D World". Instead they begin with 4D simplices and end up with a 4D world. This is no more surprising to me than starting with little cubes and ending up with big cubes. Please correct me here. I see this as just a gravity from QM paper, not something that separates metric from manifold.

Carl

[marcus]

. I saw no "emergence of a 4D World". Instead they begin with 4D simplices and end up with a 4D world. This is no more surprising to me than starting with little cubes and ending up with big cubes. Please correct me here.
...

One way to understand it is to read the paper carefully and follow their references to the literature.

It may be that you have not read the first page of the article, Carl. this is page 2 (the abstract occupies page 1). Here is a quote from page 2:

----quote from "Emergence of a 4D world---
Note that the dynamical nature of “dimensionality” implies that the Hausdorff dimension of the quantum geometry is not a priori determined by the dimensionality at the cut-off scale a, which is simply the fixed dimensionality d of the building blocks of the regularized version of the theory. An example in point are the attempts to define theories of quantum geometry via “Euclidean Dynamical Triangulations”, much-studied during the 1980s and ‘90s. In these models, if the dimension d is larger than 2, and if all geometries contribute to the path integral with equal weight, a geometry with no linear extension and dHausdorff= infinity is created with probability one. If instead – as is natural for a gravityinspired theory – the Boltzmann weight of each geometry is taken to be the exponential of (minus) the Euclidean Einstein-Hilbert action, one finds for small values of the bare gravitational coupling constant a first-order phase transition to a phase of the opposite extreme, namely, one in which the quantum geometry satisfies dHausdorff= 2. This is indicative of a different type of degeneracy, where typical
(i.e. probability one) configurations are so-called branched polymers or trees (see [11, 12, 13, 14, 15, 16, 17] for details of the phase structure and geometric properties of the four-dimensional Euclidean theory).
----end quote----

The Dynamical Triangulations literature all through the 1990s is a history of frustration where they would put together, say, 4-simplices
and the result would be something of small dimensionality like 2
or the dimensionality would go off to infinity.

the 2004 result reported in "Emergence..." was highly nontrivial, as they say, and as they explain by reference to the earlier work.

this behavior has been discussed in quite a few papers---not just in 4D case but also in 3D

For instance look around page 7 of Loll's introductory paper "A discrete history..."
hep-th/0212340
which was written for grad students entering the field. She describes the 3D case, which is easier to picture.


in the 3D case, one randomly assembles 3-simplices (tetrahedrons), but for a decade or so the result was always something highly branched out or highly compacted---- either 2 dimensional or very high, essentially infinite, dimensional.

Loll provides some pictures, which I can't.

[CarlB]

But it's not starting from a point of "NO PRIOR METRIC". Instead they're talking about starting without a coordinate system. For example, from your very useful link:

A nice feature of such simplicial manifolds is that their geometric properties are completely described by the discrete set {l^2_i } of the squared lengths of their edges. Note that this amounts to a description of geometry without the use of coordinates.
http://www.arxiv.org/PS_cache/hep-th/pdf/0212/0212340.pdf

In fact, each of the simplices that these guys are adding up does possess a metric structure. That's what gives the squared lengths of their edges. For that matter, if one knows the squared lengths of the edges, it's easy enough to define a coordinate system and metric for the simplice (which is assumed to be flat in the above link).

This concept of getting space back from just the edge lengths of simplices smells to me of pure mathematics. It's just not amazing to me except that so many people would work so hard on it. It's like a chapter from Bourbaki. What's more, it appears to provide no explanation for any physical phenomena such as masses or coupling constants or anything else not already covered by the standard model.

Carl

Also see:
The simplicial building blocks of the models are taken to be pieces of Minkowski space, and their edges have squared lengths +a^2 or -a^2. For example, the two types of four-simplices that are used in Lorentzian dynamical triangulations in dimension four are shown in Fig.5. The first of them has four time-like and six space-like links (and therefore contains 4 time-like and 1 space-like tetrahedron), whereas the second one has six time-like and four space-like links (and contains 5 time-like tetrahedra). Since both are subspaces of flat space with signature (− + ++), they possess well-defined light-cone structures everywhere.

In general, gluings between pairs of d-simplices are only possible when the metric properties of their (d−1)-faces match. ...

So the metric nature of the simplices is quite explicit.

It seems to me that the whole difficulty in this endeavor comes from the requirement that the result be Lorentz symmetric. But there is also an apparent assumption of the existence of a global time: Creating closed time-like curves will be avoided by requiring that all space-times contributing to the path sum possess a global “time” function t.

The underlying problem here is not with QM or gravity, it is in the unification. The above seems to me to suggest that the real problem is the assumption of Lorentz symmetry.

By the way, Hestenes believes that there is a method of putting gravitation onto a flat copy of his space time algebra (STA). Thus the underlying manifold would be flat. The method was found by Lasenby, Doran and Gull. If this is the case, wouldn't it make the whole problem of having to sum over bizarre geometries trivial? Here's a link to his article, please comment (as I know little about gravitation):
http://modelingnts.la.asu.edu/pdf/NEW_GRAVITY.pdf

Carl

[RandallB]

Randall it is soooooo simple. Amazing how something so simple can generate so many comments. – But rather helpful ones, as I took your advise and thought this one over a bit.

The tune up in my thinking was where I’d though of Special and General Relativity both as being Classical 4D ideas. My problem was thinking Classical as 4 D. But as said here: However, it is also possible to treat time as an independent variable. That is, one can treat time as separate from the geometry of space. --- a classical way of treating space and time. . I.E. Classical is not 4 Dimensional but 3 D with time being separate from Euclidian space.

This classical way was fine for SR with the SR equations being more precise solutions to the ones Newton provided.

But the classical was unable to depict how gravity worked. So we have the first really significant application of Riemannian geometry (from mid 1800’s I think) in order to build General Relativity. As 4D thinking to create “Warped space-time” was needed. Thus I shouldn’t think of Time by itself as being a dimension independent of three spatial ones where all four would have a metric. But instead : In Gen Rel you start with a 4D space-time manifold (without a metric) and some matter …. where you solve for the gravitational field, which is becomes the metric. So on the main point - understanding GR as being non-classical, is because of the need for Riemannian, I think I’m very clear on that and how that works.

In the QM arena :
On the issue of “perturbative” (String & M Theory) and “non- perturbative” (CDT, Triangulations) Background Independence are both of these significantly different that the BI of Gen Rel?
Is QM by definition Background Independent? with perturbative just one way of recognizing that aspect of QM.
Or is there even such a thing a Background Dependent QM theory?

Thanks for the links, and comments from all.
RB

[Juan R.]

"inefficient"

CDT path integral has not given any signs of being an inefficient approach to quantum gravity, and to the extent that one can compare the two rather different approaches I would say that it is MORE background independent than canonical LQG.

Among tested, well-established theories, General Relativity is the most background independent model we have. When quantizing Gen Rel, it is obvious to try to preserve the B.I. feature if one can. The comparative success or failure of various attempts to do this is not relevant to the validity of the effort.

With both String and canonical Loop experiencing difficulties, one sees that it is actually the most background independent approach that is currently making the most progress.

I would remark that in post #99 i said (readers could think that i said other thing since you cited to me out of context)


Do not forget that LQG is claimed background independent whereas continue to be an “inefficient” approach to quantum gravity.

[marcus]

Juan, you are doing the right thing to re-focus the discussion on the main question. I will try to prevent any misunderstanding by also giving CONTEXT of quotation. It is a very good idea. Here is my post #96

1. it doesnt mean anything unless you say FOR WHOM it is a waste of time.

2. increasing numbers of people seem to be deciding that FOR THEM it is a waste of time, and so they are getting out of the field, or they are not writing so many research papers as they did. (However on arxiv I see a growing number of string papers by people at Beijing Normal and other large Chinese universities. These people do not think string is a waste of time for them and they are responsible for an increasing fraction of the research postings.)

3. your statement does not have a clear meaning unless you specify a waste of time AS WHAT. I think a lot of people would agree that string theory can lead to ideas and results that are interesting AS MATHEMATICS.

4. your statement would not apply to a mathematically gifted young person who goes into string and discovers something interesting and valuable AS MATHEMATICS. You cannot say that such a person is wasting their time!
What gives mathematics intrinsic WORTH is the interest it evokes from other mathematicians. It does not need to be a fundamental testable model of nature.

5. however your message, suitably qualified and restricted, is a very helpful one to have expressed---and voicing it actually DOES STRING THEORISTS A FAVOR by increasing the pressure on them to arrive at a nonperturbative background independent formulation that makes falsifiable predictions. This is the only way to be sure that string theorizing is not a waste of time AS PHYSICS.

You responded in a forceful and substantive way to ALL my points in your post #99, but right now I want to focus on your reply to point 5. You argued that it would NOT BE A MAGIC CURE for the troubles of string theory for researchers to concentrate their effort on finding a nonperturbative and background independent formulation, and you gave an example where background independence has, by itself, not led to complete success (as I would freely admit.)

Do not forget that LQG is claimed background independent whereas continue to be an “inefficient” approach to quantum gravity

And I will agree with you that there are no magic cures (this was your phrase in post #99) in other words no certain method to rescue string from the landscape quagmire and make it a predictive testable theory. But nevertheless, have a look at this chart that shows my perspective and will help you understand why I think that working on a nonperturbative version of string COULD help the field advance. the percentage change is output is over the 3 years 2002-2004:


QG approach % change in output progress
strings (least indep) decline bogged down in landscape
loops (indep) increase cosmology, Freidel TFT, uniqueness theorem
triangles (most indep) rapid increase dramatic advance


strings is the least indep, assuming a manifold WITH prior metric, and it has experienced a substantial decline in research output: number of papers per year. except in China, people seem to be leaving the field.

loops is more indep, assuming a manifold WITHOUT prior metric, and has had something like 50% increase in research output, people entering the field

CDT triangles is a small field, but it is the MOST indep, and its spacetime is not even a differentiable manifold (although piecewise flat manifs are used in an approximation method). So this is radical, taking independence to a new level, and this approach has made the most pronounced progress, with percentagewise more people entering the field

Juan, you can challenge any of this because this is largely my personal perspective. Progress is hard to measure objectively and one must use individual judgement. But I am giving you this comparison chart so you will better understand my point of view.

You have argued that it would NOT help string become more predictive (that is: falsifiable) to develop a version that DOES NOT ASSUME A PRIOR METRIC. This would be the first kind of independence to ask for---a version that you can CALCULATE from without depending on a prior metric on the manifold.

My guess is that, on the contrary, it WOULD help theorists arrive at a falsifiable theory, if they would focus effort on making it nonperturbative.
Nonperturbative theories are harder to construct, and the difficulty narrows down the range of options. By denying themselves the convenience of a prior-chosen metric, the researchers might very well arrive at a theory that could be falsified through inconsistency or by experiment. This is how scientific theories are supposed to be and would constitute a kind of long-delayed success. And so i see it as a hopeful possibility---but I certainly confess that it is not a certainty!

[Juan R.]

Juan, you are doing the right thing to re-focus the discussion on the main question. I will try to prevent any misunderstanding by also giving CONTEXT of quotation. It is a very good idea. Here is my post #96



You responded in a forceful and substantive way to ALL my points in your post #99, but right now I want to focus on your reply to point 5. You argued that it would NOT BE A MAGIC CURE for the troubles of string theory for researchers to concentrate their effort on finding a nonperturbative and background independent formulation, and you gave an example where background independence has, by itself, not led to complete success (as I would freely admit.)



And I will agree with you that there are no magic cures (this was your phrase in post #99) in other words no certain method to rescue string from the landscape quagmire and make it a predictive testable theory. But nevertheless, have a look at this chart that shows my perspective and will help you understand why I think that working on a nonperturbative version of string COULD help the field advance. the percentage change is output is over the 3 years 2002-2004:


QG approach % change in output progress
strings (least indep) decline bogged down in landscape
loops (indep) increase cosmology, Freidel TFT, uniqueness theorem
triangles (most indep) rapid increase dramatic advance


strings is the least indep, assuming a manifold WITH prior metric, and it has experienced a substantial decline in research output: number of papers per year. except in China, people seem to be leaving the field.

loops is more indep, assuming a manifold WITHOUT prior metric, and has had something like 50% increase in research output, people entering the field

CDT triangles is a small field, but it is the MOST indep, and its spacetime is not even a differentiable manifold (although piecewise flat manifs are used in an approximation method). So this is radical, taking independence to a new level, and this approach has made the most pronounced progress, with percentagewise more people entering the field

Juan, you can challenge any of this because this is largely my personal perspective. Progress is hard to measure objectively and one must use individual judgement. But I am giving you this comparison chart so you will better understand my point of view.

You have argued that it would NOT help string become more predictive (that is: falsifiable) to develop a version that DOES NOT ASSUME A PRIOR METRIC. This would be the first kind of independence to ask for---a version that you can CALCULATE from without depending on a prior metric on the manifold.

My guess is that, on the contrary, it WOULD help theorists arrive at a falsifiable theory, if they would focus effort on making it nonperturbative.
Nonperturbative theories are harder to construct, and the difficulty narrows down the range of options. By denying themselves the convenience of a prior-chosen metric, the researchers might very well arrive at a theory that could be falsified through inconsistency or by experiment. This is how scientific theories are supposed to be and would constitute a kind of long-delayed success. And so i see it as a hopeful possibility---but I certainly confess that it is not a certainty!


In short, string theory fails because is NOT a theory about our universe. This validation of the theory is rather broad and is not based in specific issues like BI.

Our universe is TODAY 4D and non supersymmetric, therefore we may develop a quantum theory for 4D and nonsupersimmetriy. Perhaps tomorrow new experiments discover hidden dimensions or super partners of currently known particles, but FIRST one may develop a theory for the uinverse that we know TODAY.

The problem of 40 year of impressive failure of ST is in the violation of scientific method. String theorists followed an initial "beatiful" idea and develop a theory for 26, 10 or 11D with supersimmetry and other stuff according to mathematical incosistency of the beatiful initial idea. How there is no posibility for developing a consistent theory for 4D without supersymmetry, there is possibility for computing nothing of this world from ST. Precisely this is the history of the field on last 30 years. Nothing computed or when computed with wrong behavior (nuclear force), wrong models (spliting of metric violating GR) or discrepancies of 50 orders of magnitude between theory and data.

And all of that even ignoring recent advanced stuff that is developed in other fields of theoretical science and ignored by super masterminds string theorists (of course some are respectful and hones but others are not). Stuff known in chemistry during 30 years (see Nobel lecture by Prigogine) is being introduced these days by string theorists in a new revolution.

That is, that was known 20 or 30 years ago in other fields is the last fad for ignorant (but very arrogant) people like Witten, Vafa, Greene, Schwartz, Motl, etc.

already explained that even with 2 or 3 new revolutions, string theory continue to be a joke (irrelevant) for people working in serious stuff.

Finalize saying that the idea of nondifferentiable spacetimes is also one of my ideas, but string and M theorists (yes those that claim for the Final theory the theory most sophisticated of the world, etc, etc.) continue working with "old" differentiable manifolds (e.g. famous CY of string theory or the new G2 of M-theory).

The arrogance of many string theorists permit to me writte this hard words (that i newer wrote for other honest researchers, including trinagulation ones)

I would say that there is posibility for reduction of dimensionality on my work and contacted with the author of paper you cite time ago. We discussed the rumour that a decrease on Newton force has been measured. If finally true this is another hard knock for ST which always has claimed that Newton force may be stronger on small distances.

F = (1/r^(2+D))

with D additional dimensions. Curiously doing D = -2, that is, reduction of dimensionality, one obtains less force (if confirmed experimentally) and absence of divergences for r = 0.

This argument is not riguroius but offer an idea of the surprising things that one can learn from alternative points of view.

[Juan R.]

According to

http://www.physicsforums.com/showthread.php?t=85971

there is not violations of Newtonian force known.

[marcus]

According to

http://www.physicsforums.com/showthread.php?t=85971

there is not violations of Newtonian force known.

Hello Juan, I liked your most recent long post. We still should provide some documentation---I should supply some data for the percentage changes in research output over the 3 years 2002-2004 and so forth.
But I couldnt think of anything more to say right now.

Yes, about the short range newton law measurments. I know. Ohwilleke noted this in a thread in this section also. If you want to post on Ohwilleke's thread you might get some discussion. I dont connect this immediately to string theory because I dont find string theory very interesting and in the long run it might not be all that important. but verifying newton law of gravity at short range does seem interesting. maybe Ohwilleke or somebody will expand on this subject

GRAVITY NORMAL AT SMALL SCALES
http://www.physicsforums.com/showthread.php?t=85989

check it out. Haelfix and Chronos have already replied on that thread.

--------------------------

by the way, something different. Do you know the story (arivero told me) of the two men discussing whether a white-ish block of material soap or cheese
one says it is soap, the other says it is cheese, and to prove it he cuts a sample and starts chewing it up----he will show it is cheese by eating some.
After a while he begins to foam and bubble at the mouth, and he stops chewing and says:

"Sabe a jabon, pero es queso."

We might translate this as
IT TASTES LIKE EPICYCLES, BUT IT'S REALLY A THEORY OF EVERYTHING.
:smile:

[CarlB]

But the classical was unable to depict how gravity worked. So we have the first really significant application of Riemannian geometry (from mid 1800’s I think) in order to build General Relativity. As 4D thinking to create “Warped space-time” was needed.

This is outside my area, but there are a few physicists who are convinced that gravity can be done on a Euclidean basis. I think the best explanation is that of David Hestenes:

Lasenby, Doran and Gull have recently created a powerful coordinate-free reformulation, re¯nement, and extension of general relativity [1,2]. It is a gauge theory on °at spacetime, but it retains the attractive geometric structure of Einstein's theory.
...
Indeed, the method amounts to a new approach to differential geometry which could fairly be called gauge geometry.
...
Part II develops gauge covariant Riemannian geometry on flat spacetime. The main objective is to clarify the fundamental ideas and provide a systematic account of the definitions, theorems, proofs, and computational techniques needed to apply the spacetime calculus efficiently to any physical problem. Specific physical applications are not addressedhere; excellent examples, which amply demonstrate the computational power of the calculus, have been worked out in [1,2] and [9-13].
...

http://modelingnts.la.asu.edu/pdf/NEW_GRAVITY.pdf

Unfortunately, understanding the above paper requires a certain amount of understanding of "geometric algebra", which is a type of Clifford algebra where the basis vectors are associated with the tangent vectors at a given point of the manifold of space-time.

Carl

[Juan R.]

This is outside my area, but there are a few physicists who are convinced that gravity can be done on a Euclidean basis.

Carl

Well, the popular understanding of GR is that gravity is spacetime curvature, but this is rather difficult to believe by several motives.

1) Nobody has measured spacetime curvature directly.

2) Spacetime curvature does not imply curved space. Usual popular image of curved space around Sun is pictorial only.

3) The curved spacetime view is not exclusive. E.g. torsion formulations, Cartan-Ehelers reformulation, etc.

4) The curved spacetime view is problematic on the Newtonian limit. Far from common understanding, nobody has derived the Newtonian limit from GR. This is easy to understand. In the limit c -> infinite the curvature of spacetime may be zero like correspond to the Newtonian approach but then, if gravity is curvature, gravity may be zero. Textbook’s derivation of Newton second law is a derivation valid only when c is finite and the approximation is non linear. c finite contradicts Newtonian theory. Ehlers reformulation of GR does not obtain the Newtonian limit (even if Ehlers claims the contrary). His formulation on flat spacetime has problems: I) the splitting of curved derivatives is not unique and additional equations does not contained in GR are needed, ii) the compatibility with Newtonian limit is done invoking “asymptotic flatness”, which is experimentally unsustainable.

5) The geometric approach breaks the unification with rest of forces.

6) Far from standard claims the geometric approach of GR does not explain the misterium of gravity. This is easy to understand. In Newtonian theory, one has an equation for computing the force, but none explaining of underlying mechanism of it. In Einstein (really Hilbert-Einstein-Grossmann) theory, one has equations for computing spacetime curvature, but none explaining of underlying mechanism of it. GR substitutes the question "How does Earth know that force that Sun does" by "How does Earth know the curvature that Sun does". Far from common statements in GR literature, GR does not explain gravity.

The solution is not a geometric approach to quantum gravity. The solution is a force-like approach to GR that can be quantized more a demonstration of that GR is, strictly speaking, wrong.

Regarding your link, not only the choosing of Minkoskian spacetime metric is not correct (related to imposibility for obtaining correct Newtonian limit, that was the source for the search of alternatives like NCG and similar), moreover, i see fundamental difficulties with the "gauge" line element (7.7) that appears to be the basis of all the "gauge" approach.

[Mike2]

At best String Theory can only be an effective theory, not a TOE. This is because there seems to be nothing in String/M-theory itself that explains where the strings or membranes came from to begin with. What process creates these membranes/strings from the background? I suppose that there was a background without strings when the universe was very, very small, and then at some later time some process gave rise to strings and/or other membranes. How did that happen?

I suspect that if we knew the process by which strings/membranes come into existence, then this might give us constraints on which strings/branes can exist and allow a choice from the landscape.

[RandallB]

there are a few physicists who are convinced that gravity can be done on a Euclidean basis. I think the best explanation is that of David Hestenes:
http://modelingnts.la.asu.edu/pdf/NEW_GRAVITY.pdf
If you know of one, I’d love to see where someone makes a serious attempt at a Euclidean explanation, I’ve never seen one.

I have to disagree on David Hestenes. He cannot be talking about a Euclidean basis while using GR and Riemannian geometry. That is 4D and Euclidean is 3D where time is just a variable. GR/Riemannian is also “Background Independent” as I understand it, and Euclidean would be Background Dependent.
While the successful current theories GR and QM are not.
At least I think QM is background independent.

The ideas that wish to replace or correct GR and/or QM, all seem to get more complex in both their concept and mathematics. Maybe that’s because reality is complex.

I still feel that String theory has been successful in showing that 11 dimensions “appear” to be required. Therefore, in my opinion any proposed new theory needs to explain why that appeared to be true. That includes variations on Strings, canonical science, and even Euclidean explanations.

RB

[Juan R.]

At best String Theory can only be an effective theory, not a TOE. This is because there seems to be nothing in String/M-theory itself that explains where the strings or membranes came from to begin with. What process creates these membranes/strings from the background? I suppose that there was a background without strings when the universe was very, very small, and then at some later time some process gave rise to strings and/or other membranes. How did that happen?

I suspect that if we knew the process by which strings/membranes come into existence, then this might give us constraints on which strings/branes can exist and allow a choice from the landscape.

An effective theory for that? From ST one can compute absolutely nothing and nothing can be explained on a sound basis. ST is mathematical gulash with no link with nothing of this world.

The strings of string M theory -really one would talk of the p-branes- are really inmortal on the formulation proposed. In fact some brane inspired cosmology models claim that the big bang was (of course is just a especulation) the outcome of a collision of two 5D branes.

[Juan R.]

If you know of one, I’d love to see where someone makes a serious attempt at a Euclidean explanation, I’ve never seen one.

I have to disagree on David Hestenes. He cannot be talking about a Euclidean basis while using GR and Riemannian geometry. That is 4D and Euclidean is 3D where time is just a variable. GR/Riemannian is also “Background Independent” as I understand it, and Euclidean would be Background Dependent.
While the successful current theories GR and QM are not.
At least I think QM is background independent.

RB

I will say nothing on your claim that QM is BI.

Regarding above link you would read it first before disagree :biggrin:. Already in the abstract you can see that are talking of a flat spacetime not a flat space. See also my post #131.

The ideas that wish to replace or correct GR and/or QM, all seem to get more complex in both their concept and mathematics. Maybe that’s because reality is complex.
RB

One may simply explain world. Often this is done by the use of more complex formulations and novel mathematical tools. All attempt to quantize gravity rely on new math and concepts do not included on GR + QM.

But whereas many of others approaches focus on physical insight, ST is just a mathematical goulash around an initially "beatiful" idea that was discarded in accelerator experiments many decades ago.

I still feel that String theory has been successful in showing that 11 dimensions “appear” to be required. Therefore, in my opinion any proposed new theory needs to explain why that appeared to be true. That includes variations on Strings, canonical science, and even Euclidean explanations.

RB

Required for what? for fulfilling ArXiv with dozens of ineffective preprints? After of more than 30 years, string theory is even poor that when began.

Things are much more simple: any proposed new theory needs to explain the world like it appears to us. Today we know that the world is 4D and non supersymmetric, therefore the first quantum theory of gravity may be a formulation for 4D and without supersimmetry. Precisely this is the point of LQG and other approaches.

If at 2007, supersimmetry is experimentally observed. No problem!! your theory will continue to be correct (as Newtonian mechanics is in Formula 1), simply you will need generalize to supersimmetry.

The problem of ST and M theory is that 11D and supersymmetry, and the rest of mathematical gulash, are just a mathematical gulash added to the theory because was internally inconsistent or violated experimental data. For example supersymmetry was added ad hoc in the 80s because string theory without it predicted tachions which were newer observed :tongue2:

The aim of physics is to explain universe as it is, is not to develop a theory of "like world would be for me".

All on string theory is about things that are not about our universe. Nothing of standard model or of GR is obtained from ST. At the best, one obtains certain models (after of tricks and ad hoc asumptions) that look like but are not equivalent.

Almost any young student knows the myth that ST predicts gravity or that GR is recovered in the low energy limit but both of those claims are not true.

In fact, causality in ST is defined in a flat metric whereas causality in GR is not. Then what? In the past they say like ST is not 100% compatible with GR and ST is mathematically "beatiful" then the problem may be with GR.

In fact, you appears to ignore that only some years ago string theorists claimed that one would do not take GR "too seriously" :eek: . Even today some guys claim that one would ignore experimental data of GR in favor of string theory!!!

All of this is a nonsense, ST is outside of physics.

Those "details" are do that ST was a waste of time or in the words of P.W. Anderson

a futile exercise like physics

[marcus]

...

I still feel that String theory has been successful in showing that 11 dimensions “appear” to be required. Therefore, in my opinion any proposed new theory needs to explain why that appeared to be true. That includes variations on Strings, canonical science, and even Euclidean explanations.


strange thought, Randall

to the ancient alchemists, it appeared that all matter could be explained by combining 4 elements

shall we require of all future theories of matter that they explain why that appeared true to the alchemists?

[Juan R.]

strange thought, Randall

to the ancient alchemists, it appeared that all matter could be explained by combiniing 4 elements

shall we require of all future theories of matter that they explain why that appeared true to the alchemists?

Nice reply!!!

You explained better and shorter (= two time better) than my :smile:

[marcus]

Nice reply!!!

You explained better and shorter (= two time better) than my :smile:

I owe this entirely to your inspiring example, Juan :smile:
thank you kindly


however on another matter, I feel a deep attachment to the geometric explanation of gravity and, although I am disinclined to argue with you, I wish you would not so often castigate it with your disapproval

but if you must, by your very nature as Juan, then I guess you must

[CarlB]

If you know of one, I’d love to see where someone makes a serious attempt at a Euclidean explanation, I’ve never seen one. I have to disagree on David Hestenes. He cannot be talking about a Euclidean basis while using GR and Riemannian geometry. That is 4D and Euclidean is 3D where time is just a variable.

Look at chapter IV of this link, which is from Foundations of Physics, 35: 1-67 (2005):
http://modelingnts.la.asu.edu/pdf/GTG.w.GC.FP.pdf
http://modelingnts.la.asu.edu/html/GCgravity.html

I think the above link is a better article in its explanation of the theory than the one I originally posted.

GR/Riemannian is also “Background Independent” as I understand it, and Euclidean would be Background Dependent. While the successful current theories GR and QM are not. At least I think QM is background independent.

I believe that the standard model of QM is background dependent. Or more precisely, that it can be cast in a background dependent interpretation. Here's an arxiv article on the subject that explains it pretty much the way I see it, except that I think that background dependence is a good thing, not something to be gotten rid of:
http://arxiv.org/PS_cache/hep-th/pdf/0409/0409048.pdf

A typical QFT textbook will deal with the background dependence of the theory by showing that while the calculations do assume a background (in the form of a particular metric), the results of the calculations are compatible with Lorentz / Poincare symmetry. That is, if you assume a different reference frame, your calculation will be different but the final result will be the same. The fact that they have to show this is an indication that the theory is not in itself inherently background independent. From my point of view, this is evidence that the universe does have a "background". It's just that since we're a part of the universe, we have great difficulty figuring out exactly what that background is.

The ideas that wish to replace or correct GR and/or QM, all seem to get more complex in both their concept and mathematics. Maybe that’s because reality is complex.

Even simple equations can have very complex solutions. If one were to look at the table of the elements, one might conclude that Schroedinger's wave equation, which pretty much explains the thing, must also be complex. My guess is that simplicity should be at the core.

I still feel that String theory has been successful in showing that 11 dimensions “appear” to be required. Therefore, in my opinion any proposed new theory needs to explain why that appeared to be true. That includes variations on Strings, canonical science, and even Euclidean explanations.

I only bought one string theory text book. Different chapters in the book purport to prove why N dimensions are necessary for a consistent theory. The only problem is that N is not a constant but changes from chapter to chapter.

My guess is that quarks and leptons are the results of a two stage condensation. The second stage is the combination of left and right handed massless chiral particles to form fermions. This is almost a part of the standard model, the difference being that the standard model requires a Higgs particle to be absorbed (or emitted) at the vertices where left and right handed chiral fermions convert to each other. The first stage of the condensation is one that produces the massless chiral fermions and is beyond the scope of this discussion. But this sort of concept does get back to string theory, or at least to the concept of hidden dimensions, by the fact that if one ignores a condensation of subparticles, (that is, if one only looks at the interactions of the combined system), one will end up with unexplained degrees of freedom. These extra degrees of freedom can be naturally explained through the notion of hidden dimensions.

As an example, if two subparticles combine to form a tightly bound composite particle, we will use center of mass coordinates for the composite particle. But there will still be a set of relative coordinates for the two subparticles. Since it is a bound state, the relative coordinates will be compact and therefore will look (mathematically) like a space of compactified dimensions. This gives some hope of determining the topology of string theory from the mechanics of the subparticles.

Carl

[RandallB]

strange thought, Randall

to the ancient alchemists, it appeared that all matter could be explained by combiniing 4 elements

shall we require of all future theories of matter that they explain why that appeared true to the alchemists?Excellent point and
YES WE SHOULD
BUT - “ancient alchemists” ideas have been explained as wrong, based on current science. And we do understand how their old view of reality; lead them to think they way they did.
So that job has been done.
I also understand need for a New Theory to show the old wrong theories to be wrong to make way for a new one.
However, loudly proclaiming that GR and QM are wrong is far short of showing them to be wrong.

True enough not every idea that falls off the truck should qualifies to set yet another standard that must be disproved of proved by any future new theory. That will always be an individual judgment call. But where rigorous scientific interpretation of observations and rigorous math has been applied to build a view of a theory - some explanation as to why the theory was constructed incorrectly should be proved by a replacing better theory. Just as has been done with Alchemists Theories. If it cannot do so what makes the new theory better?
In the worst case view of both GR and QM they have certainly met that standard.
But, for all those that have better answers than GR or QM, I've never seen a reasoned explanation as to why GR and QM work so well and are yet wrong.

Now I’m no String or M theory expert, in fact I don’t see how they could be correct. But based the quality of the people and the work they have done, I trust and I believe the ideas were rigorously formed. And for me the idea of 10 or 11 dimensions was reasonable reached in this case. So for me I feel they have met the standard. Even though I do not believe in extra dimensions myself I feel it’s only responsible to accept the higher standard. Therefore if I want to show strings to be wrong, and there is something better, I must understand how they made the mistake of assuming the extra dimensions. If I can’t take the responsibility to do that, then why should anyone take a new idea seriously?

I just find this a more reasoned and logic approach to the issue rather than just cobbling a bunch of ideas together with no proofs, and no explanations of how the others made the wrong conclusions.

Is that easy to do – of course not it's harder, nobody promised easy.

RB

[selfAdjoint]

I have to disagree on David Hestenes. He cannot be talking about a Euclidean basis while using GR and Riemannian geometry. That is 4D and Euclidean is 3D where time is just a variable. GR/Riemannian is also “Background Independent” as I understand it, and Euclidean would be Background Dependent.

"Euclidean" in this context refers to any geometry where the line element ds^2 = g_{ab}dx^adx^b is positive definite. So you can have Riemannian geometry that is Euclidean. The line element of GR is not positive definite, because the "time" term is a different sign from the "space" terms.

And "background independent" is a property of the physics together with the geometry, not the kind of geometry alone. If the physics acts on the geometry, and the geometry determines the physics, so there is self-interaction, then you have background indpendence.

[marcus]

...And "background independent" is a property of the physics together with the geometry, not the kind of geometry alone. If the physics acts on the geometry, and the geometry determines the physics, so there is self-interaction, then you have background independence.

nice way to put it. points up a positive quality instead of the negative quality of not being dependent on something like a prior fixed choice of background metric. different ways of saying the same thing but more intuitive/evocative to say it in this positive way

[Juan R.]

however on another matter, I feel a deep attachment to the geometric explanation of gravity and, although I am disinclined to argue with you, I wish you would not so often castigate it with your disapproval

At the best, i think that you would only find difficulty with point 4) of post #131, since rest is standard or almost standard. And, of course, with my own solution to the problem.

I think that once the paper was published you could study it carefully and write a public comment if you consider that GR is still a good approach after of reading my work.

If i am wrong you will help to me to understand correctly gravitation :biggrin:.

If i am not wrong then I will help to you to understand correctly gravitation.

[Juan R.]

I only bought one string theory text book. Different chapters in the book purport to prove why N dimensions are necessary for a consistent theory. The only problem is that N is not a constant but changes from chapter to chapter.

Carl

Very good point!!

In fact the history of dimensions is

4D, 5D, 26D, 10D, 11D, ...

According to B. Greene some string theorists are now working in the posibility of more than one time dimension whereas others claim that the fail of compactification may indicate that there are still unknown 4D-versions of "string" theory.

Also the size of strings changes from "chapter to chapter" from "infinitely" small (Planck) to mm range to again "infinitely" small to infinitely large. There is a version that says that compactified dimension are the usual 4D ones, etc.

The rest of "theory" is also chapter-dependant and even book-dependant or author-dependant!!

[Juan R.]

Now I’m no String or M theory expert, in fact I don’t see how they could be correct. But based the quality of the people and the work they have done, I trust and I believe the ideas were rigorously formed. And for me the idea of 10 or 11 dimensions was reasonable reached in this case. So for me I feel they have met the standard. Even though I do not believe in extra dimensions myself I feel it’s only responsible to accept the higher standard. Therefore if I want to show strings to be wrong, and there is something better, I must understand how they made the mistake of assuming the extra dimensions. If I can’t take the responsibility to do that, then why should anyone take a new idea seriously?

I just find this a more reasoned and logic approach to the issue rather than just cobbling a bunch of ideas together with no proofs, and no explanations of how the others made the wrong conclusions.

Is that easy to do – of course not it's harder, nobody promised easy.

RB

This sounds like the main argument for studying string theory that some string theorists use: "Because Witten believes on it".

That is not a scientific argument.

The "quality" of people is a subjective concept and, moreover, is not guarantee of a good work. Look for example the history of QFT, almost all great guys Schrödinger, Dirac, etc. did the wrong work and a new generation of young people did QFT. In fact, this argument against string theory has been recently used by Dyson.

Regarding the "quality" of the work they have done, i could say that the quality is very low, with lot of wrong details that are corrected after of decades. Material known in other fields is introduced decades after in string theory. In concrete points, I can assure that the quality of Seiberg's work on NC geomstry is low, the quality of Schwartz's work on unitarity is low, the quality of Witten's work on QM foundations is low, the quality of Nanopoulos' work on the arrow of time problem is low, etc.


So for me I feel they have met the standard.


Curiosly the standard in quantum gravity research is not that.


Therefore if I want to show strings to be wrong, and there is something better, I must understand how they made the mistake of assuming the extra dimensions.

Curiously science does not work on that way. Are string theorists who may show that universe is 11D!! Curiously string theorists have shown nothing and none of their initial promises has been done after of more than 30 years!

It is time for exploring other alternatives.

[RandallB]

It is time for exploring other alternatives.Well at least that's one point we completly agree on.
I just hope and even expect that a good alternative will prove strings wrong by show how/why it appeared to them there should be multi D's. I'd even expect proving so can be helpful.
RB

[RandallB]

"Euclidean" in this context refers to any geometry where the line element ds^2 = g_{ab}dx^adx^b is positive definite. So you can have Riemannian geometry that is Euclidean. The line element of GR is not positive definite, because the "time" term is a different sign from the "space" terms.

And "background independent" is a property of the physics together with the geometry, not the kind of geometry alone. If the physics acts on the geometry, and the geometry determines the physics, so there is self-interaction, then you have background indpendence.
So is GR consided background indpendent ??
Does "The line element of GR is not positive definite" address this issue?

The Lee Smolin link (Thanks for finding Marcus)
http://arxiv.org/abs/hep-th/0507235
Provides a firm argument the GR is “relational” or background independent.
At least where “warping” is concerned.
Is this generally accepted as the case or is this a “debated point” ?

[CarlB]

In fact the history of dimensions is
4D, 5D, 26D, 10D, 11D,

If you attribute the hidden dimensions in string theory to internal degrees of freedom between constituents of the supposedly fundamental particles, then the varying number of hidden dimensions is an obvious indication that the number of constituents varies between the particles.

If spin-1 bosons have more internal constituents than spin-1/2 fermions, (as one might expect if all these particles were condensed from fermionic subparticles) it is quite natural that in string theory, the fundamental bosons would have a larger number of hidden dimensions than the fundamental fermions.

The quarks and leptons seem to require 10 or 11 dimensions in total, while the various gauge bosons require 26. (I'm reading Polchinski.) These numbers are about right for the spin-1/2 fermions to be composed of three fundamental subparticles, while the spin-1 bosons are composed of six. That is, three subparticle fermions would have a total of something around 12 degrees of freedom, while six subparticles would have about 24.

Various authors have proposed that the quarks and leptons are condensed states and the number of subparticles is frequently given as three. My own proposal is along this line, but is somewhat radical:
http://brannenworks.com/PHENO2005.pdf

Carl

[Juan R.]

If you attribute the hidden dimensions in string theory to internal degrees of freedom between constituents of the supposedly fundamental particles, then the varying number of hidden dimensions is an obvious indication that the number of constituents varies between the particles.

If spin-1 bosons have more internal constituents than spin-1/2 fermions, (as one might expect if all these particles were condensed from fermionic subparticles) it is quite natural that in string theory, the fundamental bosons would have a larger number of hidden dimensions than the fundamental fermions.

The quarks and leptons seem to require 10 or 11 dimensions in total, while the various gauge bosons require 26. (I'm reading Polchinski.) These numbers are about right for the spin-1/2 fermions to be composed of three fundamental subparticles, while the spin-1 bosons are composed of six. That is, three subparticle fermions would have a total of something around 12 degrees of freedom, while six subparticles would have about 24.

Various authors have proposed that the quarks and leptons are condensed states and the number of subparticles is frequently given as three. My own proposal is along this line, but is somewhat radical:
http://brannenworks.com/PHENO2005.pdf

Carl

However, in string theory, the hidden dimensions are not related to internal degrees of freedom on a 4D universe.

"then the varying number of hidden dimensions is an obvious indication that the number of constituents varies between the particles."

I do not understand to you here. The varying number of hidden dimensions is just historical one. In superstring theory, the number of dimensions is 10 and 11 in the new M theory, but is not 10D for some particles and 26D for others. Superstring theory is a priori valid for both bosons and fermions. Only the old bosonic string theory is for 26D.

I do not know if fermions are elementary or composed objects. Nobody know that, still let me highlight that in superstring, brane and M theory fermions are elementary objects, of course are vibrational states of the p-brane but are not composed of collection of branes. They are the brane itself.

[CarlB]

However, in string theory, the hidden dimensions are not related to internal degrees of freedom on a 4D universe. ... I do not understand you here. The varying number of hidden dimensions is just historical one. In superstring theory, the number of dimensions is 10 and 11 in the new M theory, but is not 10D for some particles and 26D for others. Superstring theory is a priori valid for both bosons and fermions. Only the old bosonic string theory is for 26D.

I don't mean to argue that string theory is correct, but instead to point out that the dimensional regularization that leads to various assumptions of dimensions in string theory is an argument that can also be applied to the hidden dimensions arising from multi particle bound states.

Since string theory, like Kaluza-Klein, only deals with the lowest modes, there will inevitably be many different physical arrangements that will give those same modes. In other words, by ignoring all but the lowest energy modes, the mathematics problem of defining the physical situation from the spectrum is severely under constrained. What I'm suggesting is that the modes that correspond to the standard model can be written as the lowest modes resulting from composite particles. I think that this can be done in a manner compelling in its simplicity. But when you're done with this, there may be a way to solve the string theory vacua problem, at least on a particle type by particle type basis.

Carl

[Juan R.]

I don't mean to argue that string theory is correct, but instead to point out that the dimensional regularization that leads to various assumptions of dimensions in string theory is an argument that can also be applied to the hidden dimensions arising from multi particle bound states.

Since string theory, like Kaluza-Klein, only deals with the lowest modes, there will inevitably be many different physical arrangements that will give those same modes. In other words, by ignoring all but the lowest energy modes, the mathematics problem of defining the physical situation from the spectrum is severely under constrained. What I'm suggesting is that the modes that correspond to the standard model can be written as the lowest modes resulting from composite particles. I think that this can be done in a manner compelling in its simplicity. But when you're done with this, there may be a way to solve the string theory vacua problem, at least on a particle type by particle type basis.

Carl

Aha!

Well, unfortunately i cannot help to you here. I am a bit confused on the question of unification and i do not know which could be the best (promising!) way.

- Perhaps composite particles.
- Perhaps pure geometric arguments on 4D on style of Connes program.
- Etc.

Unfortunately, i cannot valuate your proposal now. I am just focusing in quantization of pure gravity and spacetime.

[sssddd]

i would really like to know the background of the guy who says string theory is a waste of time.

[RandallB]

i would really like to know the background of the guy who says string theory is a waste of time.He has promoted links to canonical science in earlier posts here that might help. I could never make heads or tails of it though. Maybe you’ll have more luck.