Is String Theory A Waste Of Time?

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Demodocus said:
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.
 

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  • #2
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Juan R. said:
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.
 
  • #3
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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.
 
  • #4
Chronos
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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.
 
  • #5
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Igor_S said:
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[/URL].

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:
 
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  • #6
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Locrian said:
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?
 
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  • #7
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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 [Broken]

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?
 
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  • #8
Hurkyl
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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.
 
  • #9
Hurkyl
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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.
 
  • #10
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string theory is a waste of time

Berislav said:
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

Schwartz said:
Be that as it may, the attempts to construct a string theory of hadrons were not fully successful.
Berislav said:
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 [Broken]
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

Lindé said:
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

Lindé said:
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

Lindé said:
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.

Berislav said:
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.

Berislav said:
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?

Berislav said:
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 [tex]dx[/tex] is

[tex]
dx = vdt
[/tex]

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

[tex]dx = vdt + fdt[/tex]

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

[tex]
\langle f(t) \rangle = 0
[/tex]

and

[tex]
\langle f(t)f(t') \rangle = cte \ \delta (t-t')
[/tex]

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.

brunardot said:
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!!!

brunardot said:
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.

brunardot said:
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!!

Hurkyl said:
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.

Hurkyl said:
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:

Keay Davidson said:
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."
 
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  • #11
Tom Mattson
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Chronos said:
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:

JuanR said:
- 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.
 
  • #12
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Tom Mattson said:
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.

Tom Mattson said:
How can we know that these points are true?
Studying them, as it is normal in science!


Tom Mattson said:
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.
 
  • #13
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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.

Berislav said:
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.
 
  • #14
Tom Mattson
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Juan R. said:
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.
 
  • #15
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Falling "up"

Demodocus said:
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?
 
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  • #16
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Berislav said:
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).

Berislav said:
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.

Berislav said:
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.

Berislav said:
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.

Berislav said:
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.


Berislav said:
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?".
 
  • #17
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Tom Mattson said:
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

https://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.)

Tom Mattson said:
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.

Tom Mattson said:
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

Tom Mattson said:
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.
 
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  • #18
selfAdjoint
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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.
 
  • #19
Nereid
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Juan R. said:
Berislav said:
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?)?
 
  • #20
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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.

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
 
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  • #21
416
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selfAdjoint said:
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.

Nereid said:
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.

Berislav said:
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.

Berislav said:
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”

Berislav said:
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.

Berislav said:
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.

Berislav said:
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 theorist Seiberg said:
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.
 
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  • #22
marcus
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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:

Berislav said:
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?

Berislav said:
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
https://www.physicsforums.com/showpost.php?p=677612&postcount=7
https://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:

Juan R. said:
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.
 
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  • #23
marcus
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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.
 
  • #24
marcus
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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...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.
 
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  • #25
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marcus said:
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: https://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.
 

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