How to explain the benefits of string theory to my grandmother

[chrisina]

My grandmother asked me "what has string theory achieved so far ?"
(poor her, she seems to think I could answer that question, so I tried my best not to deceive her...)

I gave here the analogy of a crime scene investigation (CSI):

- suppose you´re a detective (string theorist) and you are presented with a very mysterious crime scene (our universe) with aprroximately 50 indices (the fundamental constants of nature). You are asked to find the culprit (the laws of nature).
- so you think, the best approach (the scientific one) is to build a CSI model, with all the most advanced mathematics (and you even develop new ones).

In the process, you become very enthusiastic, because your model also provides better explanations on other crime related issues : for example, how a cat gets destroyed in a washing machine (black hole entropy).

- then you say : well, our conclusion, is that probably we´ll never be able to solve the crime, because our model shows that there are at least 10^300 possible culprits. But rest assured, the crime really happened, because we were there to observe it... we are pretty confident that our model is the best to explain how crimes are performed (including the one with the cat).

So my grandmother says : " so they don´t solve the crime ? Christian, you probably got it wrong"

I surely did, so now suppose I am your grandmother...

PS : despite the cynical and somewhat irreverentious tone, this is a GENUINE question.

 

[neutrino]

what has string theory achieved so far ?

Don't worry gran'ma, even the string theorists haven't answered that yet.

 

[ccdantas]

I suppose you are looking for a ST version of this:

http://arxiv.org/abs/quant-ph/0305045

 

[Demystifier]

Chrisina, in order to successfully explain the benefits of string theory to your grandmother, you have to choose a different strategy. The analogy with CSI is simply bad. I would start from the assumption that your grandmother is religious (most grandmothers are) and compare the benefits of string theory with the benefits of her religion. Even if she is not religious in a traditional sense, she certainly believes in something, in some ideals for which a proof does not exist, which can always be taken for a basis of the analogy.

 

[Demystifier]

An additional, more serious comment: In the modern landscape view of string theory, asking string theory to explain the Standard Model is like asking quantum electrodynamics to explain life on the planet Earth.

 

[chrisina]

come on ST fans, isn´t it possible to find at least one single, easy to explain achievement for a theory which has cost more than 10000 man year of cumulated effort... ?

 

[Demystifier]

come on ST fans, isn´t it possible to find at least one single, easy to explain achievement for a theory which has cost more than 10000 man year of cumulated effort... ?

Let me compare it with religion. Has religion (that costs much more) made any achievement? One may say that it gave us a hope. Well, so did ST.

 

[CyberRBT]

chrisina:
What has ST achieved thus far (in our verse)? Well ... it has managed to voraciously devour 10K man-years from some of the best theoretical minds on our planet. :)

Perhaps a less conCERNed model of comparison is in order. This is what i would tell my grandmother.

"What has a one-month old baby achieved? What has a two-month old baby achieved? Granny, string theory is that eager infant squirming in its crib. Right now she mostly sleeps, but she is starting to interact with us and sometimes you can catch her smiling. She's developing from head to foot. Lots of good folks are attentively working with baby Esstee teaching her to talk and to walk. They feed her; clean her; clothe her; and, they enjoy playing with her. Soon, she will talk ... soon, she will walk. And, granny, when she learns to run you won't need to ask 'what has she achieved'. Instead, you'll be installing child safety gates, double-locking the cabinets, and wondering where she gets all that energy."


Demystifier: (deify timers?)
Religion is religion, and ST is ST; never the twain shall meet? Or, shall they?

 

[Leopold Infeld]

I thought there were 10^500 culprits give or take?

Eric Cartman would have made the best investigator :P

 

[Demystifier]

This is what i would tell my grandmother.

"What has a one-month old baby achieved? What has a two-month old baby achieved? Granny, string theory is that eager infant squirming in its crib. Right now she mostly sleeps, but she is starting to interact with us and sometimes you can catch her smiling. She's developing from head to foot. Lots of good folks are attentively working with baby Esstee teaching her to talk and to walk. They feed her; clean her; clothe her; and, they enjoy playing with her. Soon, she will talk ... soon, she will walk. And, granny, when she learns to run you won't need to ask 'what has she achieved'. Instead, you'll be installing child safety gates, double-locking the cabinets, and wondering where she gets all that energy."

The best answer so far. Now I will tell to my grandmather the same.

 

[Fra]

The best answer so far. Now I will tell to my grandmather the same.

As long as we have faith in the method I'd buy this. But the method is exactly my personal problem with string theory, thus I would have no faith in the result if there is no other proof than self consistency. Self consistency alone, devised by means of a line of reasoning that isn't very attractive.

Since our attempts is considered to be an investment, the minimum requirement I would like is to justify the method, not hope that maybe or maybe not the result can be justified.

/Fredrik

 

[neutrino]

Granny better not have watched those Discovery Channel shows where they talk about the growth of a baby, and what they achieve (as human beings) as they become a year or two old.

 

[CyberRBT]

neutrino:
One can not ignore the gravity of your admonition. :)

 

[Demystifier]

As long as we have faith in the method I'd buy this. But the method is exactly my personal problem with string theory, thus I would have no faith in the result if there is no other proof than self consistency. Self consistency alone, devised by means of a line of reasoning that isn't very attractive.

Since our attempts is considered to be an investment, the minimum requirement I would like is to justify the method, not hope that maybe or maybe not the result can be justified.

Unfortunately, as we cannot do experiments at energies as large as the Planck scale, self-consistency is the only guide. There are only two possibilities: We can either not even try to say anything about phenomena on these energies, or try to do the best using only what we have - self-consistency. One should not forget that general relativity (GR) was also constructed from almost nothing but self-consistency. As GR latter turned out to be correct, it does not seem so unreasonable to hope that string theory could be right as well.

 

[Fra]

Unfortunately, as we cannot do experiments at energies as large as the Planck scale, self-consistency is the only guide. There are only two possibilities: We can either not even try to say anything about phenomena on these energies, or try to do the best using only what we have - self-consistency. One should not forget that general relativity (GR) was also constructed from almost nothing but self-consistency. As GR latter turned out to be correct, it does not seem so unreasonable to hope that string theory could be right as well.

Yes, but consistency has meaning only within a given foundation. At best it seems string theory is trying to answer how the universe will look like, if the minimum block is a string, and everything else is explained in terms of string dynamics.

But IMO that is the answer to the wrong question. String theorists seem to pose both the question and and answer to make them consistent.

I can not wrap my head around the idea that these string ideas can qualify as some kind of first principles. It's at special case, or IMO weird approach at best. I can buy that. So even if it ends up useful, it is still not possibly the final answer. So I see no reason at all that I should waste my time on earth, trying to the the answer to a question that I find wrongly posed to start with. In a certain sense posing the right questions is part of the problem, and often part of the solution involves reformulating the question. But still. In my thinking the whole string philosophy is too off target to get my attention. Wether that's due to string theory, or my incompetence, does in fact not matter from my subjective point of view, because any incompetence is intrinsic and not something I can choose away in fractions of a second.

However, perhaps you're right that there hasn't been much options around. I'm too young and ignorant about the exact history to have an opinion on that, but I will speak for myself today and currently I see some very exciting approaches that IMO, outperforms string theory in its ambitions. However these approaches are too young to be able to compete on total progress level, but to me the string route is not radical and fundamental enough. Mathematically fancy maybe. But that's not what physics is about for me at least. I want a clean, logically and philosophicall consistenct line of reasoning behind all this.

/Fredrik

 

[Fra]

> So my grandmother says : " so they don´t solve the crime ? Christian, you
> probably got it wrong"

Perhaps we may have understimated old grandmothers wisdom ;)

/Fredrik

 

[Anonym]

So my grandmother says : " so they don´t solve the crime ? Christian, you probably got it wrong"

I surely did, so now suppose I am your grandfather...

Christian, suppose that there is no crime, do not exist. How do you explain that?

Grandfather.

 

[CyberRBT]

re: Planck, i believe it was he who said

"A new scientific truth does not triumph by convincing its opponents and making them see the light, but rather its opponents eventually die, and a new generation grows up that is familiar with it."


Fra:
If we reflexively reject an established though nascent scientific/mathematical pursuit predicated on its inability to fit snugly within our own conceptual framework, how else can we establish the foundation upon which to attain your next 'radical' superset of theories? Perhaps some independent, punctuated theory will abruptly emerge. But, until we have repeatable experimental validation there is, IMO, no substantive differential between the "fancy math" of ST and "mathematical genius".

 

[Demystifier]

Christian, suppose that there is no crime, do not exist. How do you explain that?

Possible in principle, but not very likely. Every society we know has crime.

 

[mjsd]

My grandmother asked me "what has string theory achieved so far ?"
(poor her, she seems to think I could answer that question, so I tried my best not to deceive her...)

Was she really asking a question or being cynical? Now if she was just asking a genuine question on the status/development of string theory, you could go on for hours/days to tell her all the exciting (and frustrating) development. If she was being cynical, ie. she was really asking "WTF is the use for String Theory?" then there are two approaches (at least) in my opinion to answer the question
First choice is to (pretend you don't understand what she is getting at) ask back "what do you mean by what has ST has achieved? ST has achieved more things than we can ever comprehend, it is like God itself who has done so much for mankind and yet we constantly take things for granted and when things don't work to our satisfaction, we start condemning..."

Second choice is to (become like her) and reply "not a lot really, just enough to stir up some interest/fundings for those who really love knowledge and doing it as a hobby. It is quite fun sometimes too, doing integrals with weird symbols, it is like playing scrabble!"

cheers

 

[Anonym]

Possible in principle, but not very likely. Every society we know has crime.

You are right, but 10^300 or 10^500 culprits is much more even than entire Moslem world. Do not look reasonable.

Regards, Dany.

 

[Anonym]

ST has achieved more things than we can ever comprehend, it is like God itself who has done so much for mankind.

I have impression that even God itself can’t ever comprehend ST achievements.

Regards, Dany.

 

[Fra]

Fra:
If we reflexively reject an established though nascent scientific/mathematical pursuit predicated on its inability to fit snugly within our own conceptual framework, how else can we establish the foundation upon which to attain your next 'radical' superset of theories?

Naturally each individual has the benefit to place his own bets and the proof is in the success. "My" bets implies "my potential loss" or "my potential gain", ultimately my responsibility.

In general I'm in favour for multiple attempts. I think that those who have
their heart in string theory should go for it, no doubt.

In general I'm in favour for multiple attempts. But part of the complicating factor with "public research" is the public funding of scientific research for benefit of the public. I guess this is partly a political question, which I've chosen to stay out of. But, I am not pleased to see my share of tax money going into string research.

Perhaps some independent, punctuated theory will abruptly emerge. But, until we have repeatable experimental validation there is, IMO, no substantive differential between the "fancy math" of ST and "mathematical genius".

I see differences in *risk*. The whole idea with risk analysis is that you don't know, thus you have to guess. But you can further just "estimate the risk". But it's true that different people may make different judgments. I can buy that. If that's as far as we can agree, that's fair enough. I make my bets and you place yours. I guss time will show what grows faster. But for a fair game I think the financial support should be in proportion to the estimated benefit. It's true though that splitting a small amount of money in too many bins, will not be efficient either. But I am still doubtful.

You might think similary, that since nonone can predict the stock market, you might place your bets arbitrary - it's just a potluck game anyway. But that is un unsatisfactory idea to me. If it's truly random - don't play! (ie take minimal risks). Humanity has plenty of other research areas to feed as well. Many that is extremely interesting. If it is not potluck, there should be discriminating evidence to what is the better place to bet (assuming you have to make a single bet), ideally if the splitting isn't too degrading for performance, a risk spreading seems wise.

To me string theory is a true high risk project. That might make large progress if successful, but also a large loss if wrong. To say that we have no other options and thus need to spend even more on this, sounds like those people addicted to gaming. They've already so large "investments made" that would be totally lost if they give up, so they need to keep investing and hope to "get lucky".

Getting lucky isn't what I associate with scientific methods. I picture that a good bet is one that can be fully defended even in the event is is proven wrong. How would the string community defend this in the event it's wrong? Was it the only choice we had? really? Was it the best bet?

I am not to judge anything or anyone but "in my world", I don't understand how string theory is up to standard in what I picture as a scientific method. It's is too speculative. Nothing wrong with that as such, the problem I have is that there seems to be no ranking of the degree of speculation and that just bugs me to the bones. Of course I'm just an amateur, and no professional. But I make my own judgements like everyone else should.

I guess am a happy fool :shy:

/Fredrik

 

[Demystifier]

You are right, but 10^300 or 10^500 culprits is much more even than entire Moslem world. Do not look reasonable.

I do not find unreasonable to have such large numbers. In fact, it is more surprising to me that this number is finite, rather than infinite. This is just the number of stable solutions. Loosely speaking, one can compare it to some simple classical equation of motion in which the number of stable solutions may very well be infinite, which usually nobody finds problematic.

I also like to put it this way:
Asking string theory to explain the Standard Model of particles is like asking quantum electrodynamics to explain life on Earth.

 

[Anonym]

You are presented with a very mysterious crime scene (our universe). You are asked to find the culprit (the laws of nature).

I do not find unreasonable to have such large numbers. In fact, it is more surprising to me that this number is finite, rather than infinite. This is just the number of stable solutions. Loosely speaking, one can compare it to some simple classical equation of motion in which the number of stable solutions may very well be infinite, which usually nobody finds problematic.

Yes, loosely speaking, you ignore Chrisina’s definitions. The universe is not a crime scene and the laws of nature are unique, moreover, extremely exceptional.

Indeed, it is matter of attitude.

Consider, for example, P.A.M. Dirac, Proceedings of the Royal Society, A133 , 60 (1931). It ignites my curiosity: if so, why it is not there? The alternative is what would happen if it would be there? Amusingly, usually that attitude is presented by the people that claim that the moon is there only when they look at it and denies the existence of photon. Chrisina consider that kind of activity “sexy”, I agree that this is kind of sexual activity but use a different name.

In the process, you become very enthusiastic, because your model also provides better explanations on other crime related issues: for example, how a cat gets destroyed in a washing machine (black hole entropy).

Ask Begemot about his opinion. I guess he will answer:” It, in my view, cheap consideration, however, your judgment is better indeed.”

Regards, Dany.

 

[Demystifier]

Y Amusingly, usually that attitude is presented by the people that claim that the moon is there only when they look at it and denies the existence of photon. Chrisina consider that kind of activity “sexy”, I agree that this is kind of sexual activity but use a different name.

Yes, there is something sexy about it. For analogy, no woman is sexy when nobody looks at her.

 

[rewebster]

Yes, there is something sexy about it. For analogy, no woman is sexy when nobody looks at her.

I read someplace that one of the reasons that there was a flurry of 'new' work being put out around the year 1900 was that science/physicists had 'used up' most of the possibilities of the 'classical' theories, and that something/anything would seem 'more' interesting. This may the case with 'string/MWI theory' too. With Quantum and relativity, 'they' thought had been researched to death and 'anything' would be more interesting (sort of like a 'new' hair style for a woman).--so, maybe, tell your dear ol' grandma that 'string theory' is like a NEW designer dress! (you know, make it relate to her).

 

[chrisina]

First of all, to mjsd, no, my grandmother was not being cynical, but genuinely interested in the question. I had just shown her this "elegant universe" TV show that I found via this forum. The thing, you should meet my grandma, she's going on her 95th birthday but is still very alert and loves to keep up to date ... maybe the fact that, as a young woman she was between 1932 and 1939 the secretary of a certain Louis de Broglie at the Paris University is for something...
Secondly, I do not buy in the "fun / sexiness" arguments. I am passionately convinced that we are living some of the most exciting years in Physics since the 1920s, because there seems to be so much we need to understand again. I mean so much Fundamental we need to understand.

 

[marcus]

I am passionately convinced that we are living some of the most exciting years in Physics since the 1920s, because there seems to be so much we need to understand again. I mean so much Fundamental we need to understand.

You are right.

Also I believe the Prince was a gentleman. It was a happier position than being, for example, the secretary of Schroedinger.

 

[rewebster]

---Well, then,--not just a hypothetical situation about a 'grandma'--hmmmm-- I might tell her that most of the 'better' theories didn't have any, even minor, results of related experiments to help support those theories until years later, and that, since 'string theory' is complex, it may be a while, like the other 'earlier theories' to have supported and related data from 'not yet conceived' experiments.

Could you ask her if she has any 'stories' about de Broglie that she would like to share?

--------------------------------------------
I'm not a string/MWI enthusiast still though.

 

[chrisina]

Rewebster, if I may disagree : let's take two examples of what may be considered as "good" and fundamentally new theories : General Relativity and Quantum mechanics.
GR was written in 1915, and it immediately could explain what was then a mystery at the time, the anomalous perihelion precession of Mercury. It only took 4 years for Eddington to come up with a series of experiments / observations on stars near the eclipsed sun that confirmed GR. I could add the failure to explain Michelson / Morley's experiments (1897) which by far preceeded the advent of GR...
Let's look at the history of quantum mechanics, you will see again a recurring theme : the failure of understang current experimental results gave rise to "new Physics" :
1900 : failure to understand the reason for the pattern of black body radiation (1862): Planck introduces quantization of energy
1905 : failure to understand the photoelectric effect (1839) : Einstein, based on Planck's quantum hypothesis introduces the new theory of light
1913 : failure to understand the Rydberg formula (1888) : Bohr introduces his new model of the atom based on the 2 previous ideas

etc...

As you can see, science progressed fundamentally because of it's failure to understand experimental results which had already been carried.

I believe we have now a BEAUTIFUL case of the same : our failure to understand the cosmological constant problem.

If the only way we can explain it is to resort to the anthropic landscape of string theory, me will miss on an opportunity to discover fundamentally new things.
Because let's not forget that the main motivation to do theoretical physics, is not to have "fun" (although of course I am not excluding it...), but the conviction that it is the most profound way for mankind to improve its ability to exploit the resources of nature.

 

[Anonym]

Let's look at the history of quantum mechanics, you will see again a recurring theme : the failure of understang current experimental results gave rise to "new Physics" :
1900 : failure to understand the reason for the pattern of black body radiation (1862): Planck introduces quantization of energy
1905 : failure to understand the photoelectric effect (1839) : Einstein, based on Planck's quantum hypothesis introduces the new theory of light
1913 : failure to understand the Rydberg formula (1888) : Bohr introduces his new model of the atom based on the 2 previous ideas

etc...

Could you complete a list down to end of 20 century?

Regards, Dany.

 

[rewebster]

Rewebster, if I may disagree : let's take two examples of what may be considered as "good" and fundamentally new theories : General Relativity and Quantum mechanics.
GR was written in 1915, and it immediately could explain what was then a mystery at the time, the anomalous perihelion precession of Mercury. It only took 4 years for Eddington to come up with a series of experiments / observations on stars near the eclipsed sun that confirmed GR. I could add the failure to explain Michelson / Morley's experiments (1897) which by far preceded the advent of GR...
Let's look at the history of quantum mechanics, you will see again a recurring theme : the failure to understand current experimental results gave rise to "new Physics" :
1900 : failure to understand the reason for the pattern of black body radiation (1862): Planck introduces quantization of energy
1905 : failure to understand the photoelectric effect (1839) : Einstein, based on Planck's quantum hypothesis introduces the new theory of light
1913 : failure to understand the Rydberg formula (1888) : Bohr introduces his new model of the atom based on the 2 previous ideas

etc...

As you can see, science progressed fundamentally because of it's failure to understand experimental results which had already been carried.

I believe we have now a BEAUTIFUL case of the same : our failure to understand the cosmological constant problem.

If the only way we can explain it is to resort to the anthropic landscape of string theory, me will miss on an opportunity to discover fundamentally new things.
Because let's not forget that the main motivation to do theoretical physics, is not to have "fun" (although of course I am not excluding it...), but the conviction that it is the most profound way for mankind to improve its ability to exploit the resources of nature.

my, my, MY...


I wasn't expecting such an intensive reply from your grandmother...



...but she seems to be agreeing with me rather than disagreeing with me as to the amount of time it takes sometimes to get a result from a hypothesis/theory/initial observation to 'some kind' of a example/result to help the 'unknown' initial query along.



...and I can guess that you haven't read some of my other answers (in other threads), then, about the 'unknowns'/fundamentals; as I try to promote the 'search' and not to accept them as 'givens' and to try to understand more of the 'reasons' of what the 'fundamental' classical processes are.

 

[chrisina]

... the point I was making (not my grandmother), is that experimental confirmations came relatively quickly after the first "good" hypothesis were made. And this despite the very revolutionary character of these hypothesis.

Try to think of someone living in the early 1900s and you get two "crackpots" like Planck and Einstein who come up with their crazy theories. How long did it take before the first experimental confiirmations came ? A few years. How long before general scientific consensus that they had found something really interesting, a bit longer.

I watched the debate between Smolin and Damour online, and this issue of the criticality of speed in the experimental confirmation came up.

This is precisely the main objection to String theory, people have been working on it for more than 25 years, and still no light of any experimental confirmation... This never happened in the past.

 

[rewebster]

How long of a 'time' period was it between Newton's 'ideas' and Einstein's 'ideas'?

Atoms were 'purposed' in Greek times---how long did it take to substantiate THAT claim?


----------------------------
--and then there were a lot of astronomical observations back in medieval times...
------------------------------

... the point I was making (not my grandmother), is that experimental confirmations came relatively quickly after the first "good" hypothesis were made. And this despite the very revolutionary character of these hypothesis.

Try to think of someone living in the early 1900s and you get two "crackpots" like Planck and Einstein who come up with their crazy theories. How long did it take before the first experimental confirmations came ? A few years. How long before general scientific consensus that they had found something really interesting, a bit longer.

I watched the debate between Smolin and Damour online, and this issue of the criticality of speed in the experimental confirmation came up.
This is precisely the main objection to String theory, people have been working on it for more than 25 years, and still no light of any experimental confirmation... This never happened in the past.

I think you're looking at the trees rather than the forest here (taking/*looking at* specific examples rather than the larger overview of the 'history' of most initial/starting points of a thought to 'some' additional supporting data)




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

Again, I am not a string/MWI person. I like the classical, semi-quantum, causality with a perspective/touch of relativity view.

 

[Anonym]

As you can see, science progressed fundamentally because of it's failure to understand experimental results which had already been carried.

I believe we have now a BEAUTIFUL case of the same : our failure to understand the cosmological constant problem.

What is the experimental value of the cosmological constant?

Apparently you miss a point. There are always tons of the experimental results which we fail to explain and understand (yet). Some high IQ people choose simply to ignore them. But this is not a matter. The matter is how to extract the universal experimental result crucial for formulation of the adequate physical theory.

I will give you three examples related with A. Einstein and one after his death:

1.The inertial and gravitational mass is identical (known about 400 years since Galileo).
2.The pattern of black body radiation (the peaceful coexistence of CED and QED, known since I.Newton). It was demonstrated by Y.B. Zeldovich et al that with the gravitation the situation is the same.
3.The collapse of the wave packet called The Measurement Problem (known since the 1920s).

and

4.The stability of proton (known since 1980s; the existence of QM ground state in the QCD).

Let me define the experimental result crucial for formulation of QG: the universe is 4-dim space-time continuum with the signature {+,-,-,-}. Only the consideration which will naturally contain the explanation of that has chance to be adequate after the proper development.

If you believe that without deep understanding of QM you will be able to understand anything in gravitation you are hopelessly naïve.

Indeed, any kind of the scientific research is legitimate, except one: it seems that your QG friends (ST, LQG, Cosmology model makers, etc) are involved too much in the PR activity, which has nothing to do with the science (compare with the ugly history of EPR).

Regards, Dany.

 

[chrisina]

Rewebster, sorry to say, but you are again missing my point :

before Newton, there was a lot of experimental data about the movement of the planets, but no theory which could explain it. Newton came up with a new theory (the word is even too small), and it din't take long for a wealth of experimental data (unknowns of the past + new predictions) to confirm that it was a "good" theory. The fact that it took 300 years before Einstein could improve it doesn't eliminate the fact that Newton's proposal was right on and very quickly confirmed by experiments.

About the greeks and the atoms, I do not call a vague supposition a scientific theory. For example, I can make a supposition like :
" the universe is actually a giant atom", but I'd need to substantiate it with some scientific theory.

About the experimental value of the cosmological constant, I just don't understand what that sentence means. The cosmological constant has no experimental value per say. It's like saying, "what's the experimental value of Planck's constant".
My point was, there are experiments, called WMAP, COBE, etc... that seam to indicate that there is a small cosmological constant, but there does not exist today any quantum field theory which can explain its value, by orders of magnitude...

About your affirmation that the apparent fact that we live in 4d space time continuum {+,-,-,-} is the most important experimental result for the formulation of QG, I will refrain from any comments...

 

[Anonym]

About the experimental value of the cosmological constant, I just don't understand what that sentence means. The cosmological constant has no experimental value per say. It's like saying, "what's the experimental value of Planck's constant".

and

there are experiments, called WMAP, COBE, etc... that seam to indicate that there is a small cosmological constant.

Ask your grandma to give you the calmative tablets.

Bye.

 

[rewebster]

Anyone at anytime is living in the 'present'---by living in the 'present' , we have the ability to look at 'history' in hindsight (with *mostly* 20/20 vision).

before Newton, there was a lot of experimental data about the movement of the planets, but no theory which could explain it.

but, they did try to come up with different theories

Newton's proposal was right on and very quickly confirmed by experiments.

A lot his were observations of the physical--different story, different set of knowledge for the time

You, chrisina, (and all of us really) have the ability to pick and choose your topics and your comparisons of all that has come before, look at them from a 20/20 hindsight, AND compress them (compress the timeline) to make the comparisons. Looking at string/MWI, WE ARE living in the time when it is now being looked at (very little 20/20 hindsight and time compression to work with). Some of your comments about the 'lack' of any progress/discoveries with string/MWI sound more like personal frustration rather than seeing the 'bigger picture' of how long 'some' ideas and theories take to have some/any substantiation.

Do you have some reason why you keep using "experimental value of the cosmological constant" as an example?


From my personal viewpoint, string/MWI may NEVER have any experimental data related on a grand scale (as a complete system/theory), but there may be small related outcomes that are generated from experiments that were initially started as 'research' into string/MWI. It's been over a hundred years and we have made no 'macro' object come even close to c (speed of light) to get data/conclusive experimental results about that part of relativity.

And IF I am still 'missing your point'--sorry, you're not still defining the 'point' you're trying to make clear enough. I think part of the problem is that you wanted/posted what/how/why string/MWI has produced (for granma), and you're also bringing into conversation points that bother you.

 

[chrisina]

Yes, you are right, it does bother me a bit that there still has been no experimental confirmation of string theory.
I mean, like many, I had been attracted to it via the media PR touting that it was "the theory of Everything"...
Now, it is clearer to me that it is just work in progress and I think it should be communicated that way. I agree that in the future, it could be that String theory is shown to be the right approach, or as you say that new roads emerge thanks to string theory which become the right approach.

My point in the earlier posts had been that experimental confirmation of "good" theories had followed relatively quickly. Which is probably what explains a growing "unease" of parts of the scientific community towards string theory.

As far as the cosmological constant problem is concerned, I referred to it as an example of an apparent experimental result which had no theoretical explanation so far. The link with String Theory being that some people (eg L. Süsskind- sorry if I misspell) are now advocating the fact that out of the 10^500 (or whatever) versions of ST possible, one could be compatible with the universe we live in, and with the value of the cosmological constant observed so far.
And, yes, this bothers me as an explanation. But to be perfectly honest, it's just gut-feal...

 

[marcus]

...
About the experimental value of the cosmological constant, I just don't understand what that sentence means. The cosmological constant has no experimental value per se. It's like saying, "what's the experimental value of Planck's constant".
My point was, there are experiments, called WMAP, COBE, etc... that seem to indicate that there is a small cosmological constant, but there does not exist today any quantum field theory which can explain its value, by orders of magnitude...

Hi chrisina, I think you are saying something interesting here which may need clarification. I don't want to get involved in arguments with the other posters---I just want to satisfy my curiosity.

I agree that Planck's constant is not a dimensionless number, so per se (by itself, purely of itself) it has no experimental value. Perhaps the most obvious value for it to have is 1, exact unity :-) but no experiment I can imagine would establish this.

If this is what you are saying about Planck's constant, I certainly agree. But I am not sure of what you are saying about the cosmo constant. It is a fascinating quantity.
I like to imagine it as a curvature-----or as an area, inverse of that curvature----or as a length, the square root of that area.

also as an energy density of about 0.6 joules per cubic kilometer,
or as a pure number of around 10^-120, when one makes
G = hbar = c = 1.

and perhaps it does not even exist!

(I found the recent paper "The Dark Side of a Patchwork Universe" by Martin B. provocative----in there the cosmo constant is merely an illusion and the observed acceleration comes from correction in the kinetic term of hamiltonian---it is appealingly simple and also shows a humorous teasing aspect of nature, that one could picture as a playful "see, I fooled you" smile.)

So I am hoping you will say a bit more about your point of view on the cosmo const. I think I might be interested in what you have to say.

 

[rewebster]

Most theories (probably the ones that you 'like' that have had some 'confirmation') -that are used- are based on observations, thoughts on observations, flukes in experiments that led to theories, etc., and after the initial theory, variations/interpretations can follow. String/MWI isn't--it's origins, from all that I've read, are math based (the origin is a math equation)-then related to observables. To me, its like saying, 'I've found this equation that looks like its important, "1=1"!, and THEN relating it to the entire universe.

I still think the "experimental confirmation of "good" theories had followed relatively quickly" are the ones that 'stand out' and that 'you like' and 'can relate to', and a lot of them take a while to 'confirm' in the time line.


by the way, did you ask granma if she had any 'good' stories from back 'when'?


------------
OOOps---I was writing and posted the above when the one you (marcus) posted appeared---My "1=1" didn't refer to your post at all. co-incidence!

 

[Anonym]

I just want to satisfy my curiosity.

You may satisfy your curiosity reading a good high school introductory textbook in physics.

 

[chrisina]

I think there is a misunderstanding (probably because of the word "value")
I stated in post #31 :

"As you can see, science progressed fundamentally because of it's failure to understand experimental results which had already been carried.
I believe we have now a BEAUTIFUL case of the same : our failure to understand the cosmological constant problem.
If the only way we can explain it is to resort to the anthropic landscape of string theory, me will miss on an opportunity to discover fundamentally new things. "

To which Anonym replied (post #36)
"What is the experimental value of the cosmological constant?"
and Rewebster (post #39)
"Do you have some reason why you keep using "experimental value of the cosmological constant" as an example? "

which I tried to answered in post #37 and #40.

I agree with you, Marcus, I find the Cosmological Constant problem absolutely facinating., so much so that I have been reading everything I can found related to it over the past 12 months. I did read the recent Bojowald paper on the patchwork universe and loved it.

I've been trying to come up with something similar for quite some time, except that I am not using any LQG results but a simpler deformable cubic lattice where I make use of probabilistic number theory (the riemann zeroes playing an important role) to see if I can get to a density matrix which is compatible with the standard parameters and coupling constants. It is still too immature, but I am not loosing hope. Why I am so interested with Lambda, is that it is the only parameter that I use in the model, the rest is just pure geometry and number theory.
But its still not working...

 

[chrisina]

Anonym, please stop being insulting with everybody...

 

[Anonym]

Anonym, please stop being insulting with everybody...

You miss my intention. I agree with Rewebster that your comments sound like personal frustrations. And I do not see any reason for that now, but imagine what may happen after 10 or 20 years. With dimension consideration you (as well as Marcus) did rough physical mistake. The choice of the natural units and physical meaning of that is really discussed in high school, but if you shame I suggest A.B. Migdal “Qualitative Methods in Quantum Theory”. You will not be cleverer denying mistake, it is nothing bad to return and check the point again.

I agree with you, Marcus, I find the Cosmological Constant problem absolutely facinating., so much so that I have been reading everything I can found related to it over the past 12 months.

I only attract your attention that A.Einstein studied that point and came to conclusion that lambda=0. Do what you want, but remember that A.Einstein understood something in physics in general and in gravitation in particular.

I think that this thread is over.

 

[rewebster]

About the greeks and the atoms, I do not call a vague supposition a scientific theory.

But...at that time, they (some Greeks) probably THOUGHT it was the most important breakthrough of the day.


and as far as: "a vague supposition a scientific theory."---'they' may be saying that about Einstein in 50 or 100 years.

All the work on String/MWI theory may be like on the work done on pre-Copernican astronomy.

 

[marcus]

... make use of probabilistic number theory ... to see if I can get to a density matrix which is compatible with the standard parameters and coupling constants. ...

Chrisina, do you know the conjecture of Smolin that the standard model parameters, including coupling constants, are well adapted to produce a lot of black holes?

Together, the constants of cosmology and particle physics, are at a local optimum for the condensation of galaxies and stars culminating in the collapse of stellar remnants to form black holes-----this is the hypothesis.

So far no one has been able to refute it----that is, no one has been able to think of a small change in one of the parameters which would cause the universe to be richer in astrophysical black holes.

Smolin has proposed ways to empirically falsify this hypothesis by astronomical observation (measuring the masses of neutron stars) but so far it has not been falsified by observation.

This is in the same spirit as your research interest, but by different means. You both want to see a PATTERN in the parameters of cosmology and particle physics, which might some day lead to a physical understanding.

Smolin's hypothesis is Chapter 20 of a new book from Cambridge University Press, called Universe or Multiverse edited by Bernard Carr, a professor of mathematics and astronomy at Queen Mary London.
http://www.cambridge.org/catalogue/catalogue.asp?isbn=9780521848411
I don't think I would like the entire book, but I have Chapter 20 separately and like it very much.

 

[marcus]

I see one of the posters on this thread says "THIS THREAD IS NOW OVER!"

But actually Chrisina I think you asked a very interesting question, which has not been very adequately addressed. I think that to make it more convenient to answer one should divide it into two steps.

How to explain to my grandmother the EFFECTS of the recent epoch of string dominance in theoretical particle physics...?

And only as a secondary issue, in what sense can one consider these effects to have been beneficial?

If you want to talk about the first of these two questions---the value-neutral part---then I would be willing to give it a try. I would simply ignore posts by people who do not seem to "get" it, otherwise such a discussion can become too much work. Everybody can express their views and if there is a difference, fine! There does not have to be complete agreement, nor need there be arguing or altercation either.

But if you are already tired of discussing the effects of the string epoch on physics, we can let it drop. I would certainly be content with that as well.

 

[chrisina]

Well Marcus, I think it is a good idea to split the question into two, parts, a value neutral one and a more sujective one. Would welcome here the inputs of some advocates of String theory.

I haven't started this thread in order to prove a point, ie String theory has had many benefits, or hasn't had many benefits.
I started this thread with a "genuine" question, that of my Grandmother : what are the benefits ?

I actually also like the discussion with Rewebster because it is very helpful to look at the history of science in order to find some parrallels with what is happening today with String Theory.

His point about the greeks and the atoms is a very interesting one when we look at it in the context of String Theory.

Let me try to explain my point of view :

1. there is no doubt in my mind that ST has done a lot in establishing a new conceptual framework and in the advancement of pure mathematics. These are clear benefits from a scientific viewpoint.

2. However, and this is the crutial point, the press has not chosen to communicate these benefits, but rather has chosen to portray ST as THE solution to the quest for a "theory of Everything".

3. The question then is, why did this happen ? In my view, this essentially has to do with what is implied with the word "benefit" in the mind of the press, the general public, and, my grandmother : would they accept the explanation given in point 1. as benefits ? I don't think so.

Fundamental physics has very much been portrayed in the past as the mother-science for the technological advancement of humanity (and this especially during the first half of last century). Einstein, Planck, Bohr, Schrödinger, and I'd say up to Feynman where all very well known by the general public and were seen as heroes.

The general public is not dumb. If physics is so detached from reality, they loose interest. So they only want to know, and that is the only question they keep asking again and again, is String Theory the "theory of Everything ?". In other words, is it going to have an impact on our lives and that of future generations ?
And the problem is, theoretical physisicts know very well that without experimental confirmation, that question will remain unanswered.

So coming back to the greeks and the atom, the parrallel with ST is in my view quite striking :
. as Rewebster mentionned, the greeks purposed the atom more than 2000 years ago. Did this have any benefit on peoples lives ? No, because they didn't have the means to experimentally verify it. One had to wait first for completely unrelated ideas to develop (Newtonian mechanics, then Maxwell, then Planck, then Einstein) until finally we had the means to verify it, and then only it started to have an impact on people's lives.

How long will it take before we have the means to experiment at Planckian scales ? I have no idea. But it seems to me that before that, we will need to develop new areas of Physics, for example Physics of Dark Energy. Is it related to Quantum Gravity ? Is it the theory of Everything ? Maybe not. But Dark Energy is a concrete new physical phenomena that has been discovered and has no theoretical model. And experiments can be made by improving the resolution and mesuring polarisation of the cosmic microwave background. So why not attack this problem first before one makes suppositions on grand unification ?


Check these two videos :

http://nobelprize.org/cgi-bin/asxgen.asx?id=79&type=interview&year=2006
(Interview with the 2006 Nobel Laureates in Physics, John C. Mather and George F. Smoot, 6 December 2006, the discoverers of the CMB signal.)

http://nobelprize.org/nobel_prizes/physics/laureates/1999/veltman-interview.ram
(Interview with Professor Martinus J.G. Veltman, Nobel Prize winner, in December 1999. Listen to what he has to say about "grand unification")

Well that's all folks, its just a point of view, and welcome the debate.