(finally)Falsifying String Theory by Jacques Distler

[marcus]

a theory is not science---it is predictively empty---unless there is possible some future observation which it could not accept

a specific measurement which, if it turned out against it, would refute the theory

It looks like Distler may have come through.

http://arxiv.org/abs/hep-ph/0604255
Falsifying String Theory Through WW Scattering
Jacques Distler, Benjamin Grinstein, Ira Z. Rothstein
4 pages, 2 figures

"We show that the coefficients of operators in the electroweak chiral Lagrangian can be bounded if the underlying theory obeys the usual assumptions of Lorentz invariance, analyticity and unitarity for all scales. Violations of these bounds can be explained by either the existence of new physics below the naive cut-off of the the effective theory, or by the breakdown of one of these assumptions in the short distance theory. If no light resonances are found, then a measured violation of the bound would falsify string theory."

On the surface of it, this seems to offer a TEST!

I hope this is the real thing, and would welcome it warmly in that case.

The absence of such a paper is the main thing that Peter Woit has been complaining about. And it is presumably what Feynman was objecting to when he said "String theorists don't make predictions, they make excuses."

Now this unsatisfactory situation may be changing. Let's hope.

 

[francesca]

Distler-Grinstein-Rothstein
In the absence of a light Higgs or other light resonances, a violation of the bound on (α4, α5) would indicate a breakdown of one or more basic properties of the S-matrix. [...] Most importantly, these assumptions must be obeyed for arbitrarily short distances. String theory, which is designed to be valid at all distance scales, is constructed to produce an S-matrix with precisely these properties. Giving up Lorentz invariance as a fundamental symmetry is a possibility that has been extensively studied in the literature and thus a violation of our bounds could be taken as indirect evidence for its existence.

For light Higgs they mean the usual prediction about 115 Gev, isn't it?

so, viceversa, if they find Higgs would we worry about Lorentz invariace?

 

[marcus]

For light Higgs they mean the usual prediction about 115 Gev, isn't it?

so, viceversa, if they find Higgs would we worry about Lorentz invariace?

Maybe you have found a "catch" in Distler's article. I hope someone else can answer this more definitely. To me it now seems a little fishy.
Instead of falsifying string theory, it looks like it might merely cause the theorists to switch to a DSR version of relativity---which several of the non-string quantum gravitists have already done!
The falsification would then be of string-with-strict-Lorentz
but not of (if it can be formulated) string-with-deformed-Lorentz.

Maybe that is still all right? In a sense, any kind of falsifiability is progress. Any hard prediction which, if denied by Nature, must force a major reorganization of the theory

 

[marcus]

Peter Woit said (off blog) something that makes me think he might agree with francesca, interestingly enough. It may be that, at bottom, Distler paper does not really have to do with a falsifiable test of string theory.

In any case maybe one should be cautious about drawing conclusions about what the Distler paper accomplishes or does not. Woit will probably write about the paper in a day or two, and then people will discuss at Not Even Wrong blog.

 

[selfAdjoint]

I think this passage that francesca quoted:

In the absence of a light Higgs or other light resonances, a violation of the bound on (α4, α5) would indicate a breakdown of one or more basic properties of the S-matrix. [...] Most importantly, these assumptions must be obeyed for arbitrarily short distances. String theory, which is designed to be valid at all distance scales, is constructed to produce an S-matrix with precisely these properties. Giving up Lorentz invariance as a fundamental symmetry is a possibility that has been extensively studied in the literature and thus a violation of our bounds could be taken as indirect evidence for its existence

Boils down to four boolean propositions.
H: There is no light Higgs boson (how light they mean they don't say).
N: Physics is Analytic, Unitary and Lorentzian (N for "nice").
B: The bounds they calculate are violated.
F: String theory is falsified.

And the paragraph asserts that
H => (N AND B => F)
H and B, and to a lesser degree N are empirical questions that could be verified at LHC. If you find both H and B then the only way to deny F would be to falsify N. The paper's citation on this point is to a discussion of tests of Lorentz invariance, but you could show Analyticity or Unitarity is violated instead. If H is false, that is if there turns out to be a light Higgs, then the whole argument is vitiated.

This is certainly a valid proposal for a test of falsification: whether the falsifaction stands or falls is put up to empirically testible propositions.

 

[marcus]

I think this passage that francesca quoted:Boils down to four boolean propositions...

Thanks! that lays the issues out clearly and squarely.

 

[marcus]

Peter Woit had some what I think is rather perceptive comment on Distler's paper today:

Sample quote:

"...It turns out that the author’s proposal isn’t actually a proposal to falsify string theory at all, but a proposal to falsify the idea that physics satisfies Lorentz invariance, analyticity and unitarity at high energies. This would falsify our standard ideas about QFT, but I don’t think it would actually falsify current ideas about string theory..."

http://www.math.columbia.edu/~woit/wordpress/?p=385

Any reactions?

 

[Chronos]

I had the same impression, marcus. Distler's proposal would not be a stake in the heart of string, but would rule out certain models. I seriously doubt it is even possible to falsify the fundamental premises of ST. It is a slippery fish.

 

[selfAdjoint]

Peter Woit had some what I think is rather perceptive comment on Distler's paper today:

Sample quote:

"...It turns out that the author’s proposal isn’t actually a proposal to falsify string theory at all, but a proposal to falsify the idea that physics satisfies Lorentz invariance, analyticity and unitarity at high energies. This would falsify our standard ideas about QFT, but I don’t think it would actually falsify current ideas about string theory..."

http://www.math.columbia.edu/~woit/wordpress/?p=385

Any reactions?

Based on my reading in my post #5, this is false. Distler, Grinstein and Rothstein mention the possibility of falsifying Lorentz invariance just in the spirit of examining all the options. But the TITLE of the paper refers to falsifying string theory (specifically the string theory amplitude matrix).

I usually groove on Woit's posts but I found this one ill tempered and unsound. His other criticisms of the paper, that it doesn't cover the whole case for SST falsification, is also off base; this paper has citation links to previous papers by others making the case in other ways; this paper was just a neat way to reach the same conclusion.

 

[marcus]

Based on my reading in my post #5, this is false. ...

I usually groove on Woit's posts but I found this one ill tempered and unsound. His other criticisms of the paper, that it doesn't cover the whole case for SST falsification, is also off base; this paper has citation links to previous papers by others making the case in other ways; this paper was just a neat way to reach the same conclusion.

If Woit has over-reached in his initial critique of the paper then this has a potential for lively controversy! I wonder if he has received any reaction on the blog by now. Will check presently.

 

[notevenwrong]

Based on my reading in my post #5, this is false. Distler, Grinstein and Rothstein mention the possibility of falsifying Lorentz invariance just in the spirit of examining all the options. But the TITLE of the paper refers to falsifying string theory (specifically the string theory amplitude matrix).

I usually groove on Woit's posts but I found this one ill tempered and unsound. His other criticisms of the paper, that it doesn't cover the whole case for SST falsification, is also off base; this paper has citation links to previous papers by others making the case in other ways; this paper was just a neat way to reach the same conclusion.

I know what the title of the paper says, my claim is that it is inaccurate and way overhyped, and I explain why in the posting. I've had a discussion involving e-mail from Distler and one of his co-authors. Distler just engaged in his usual melange of arrogance, sneering, refusal to address issues, and personal attacks on my competence (which has something to do with my perhaps ill-tempered tone in discussing this, and anything involving him in general), but his collaborators seem to be perfectly reasonable people who behave professionally. Based on these discussions, I see no reason to change my claim about this paper. What they are hoping to do is to get some bounds on electroweak scattering amplitudes, purely based on 3 assumptions: unitarity, analyticity and Lorentz invariance, something which would be interesting.

The assumptions they are making are standard assumptions about QFT, so if their bounds were violated it would be indication of a failure of our usual ideas about QFT. String theory is just completely irrelevant to what they are doing, note that the papers they are quoting to back up their calculations are not string theory papers. I suspect that if their bounds were actually experimentally falsified, what most string theorists would say is not that string theory has been falsified, but that QFT has been falsified, and that this implies one has to do string theory.

If their argument works, and you find violations of the bounds they promise to work out, the consequence would be that in one's high energy theory one has to give up Lorentz invariance, analyticity or unitarity. Unitarity is pretty fundamental to the whole idea of quantum mechanics, so people are unlikely to give that up. While perturbative string theory amplitudes in flat space have the assumed Lorentz invariance and analyticity properties, it is not at all clear that this is true of non-perturbative string theory, or of string theory in certain kinds of backgrounds. Some string theorists have speculated about Lorentz non-invariant backgrounds, and, as I mentioned in my posting, if non-perturbative string theory really does, as often claimed, involve getting rid of standard space-time, you quite possibly would also lose analyticity and/or Lorentz invariance.

 

[josh1]

I know what the title of the paper says, my claim is that it is inaccurate and way overhyped, and I explain why in the posting. I've had a discussion involving e-mail from Distler and one of his co-authors. Distler just engaged in his usual melange of arrogance, sneering, refusal to address issues, and personal attacks on my competence (which has something to do with my perhaps ill-tempered tone in discussing this, and anything involving him in general), but his collaborators seem to be perfectly reasonable people who behave professionally. Based on these discussions, I see no reason to change my claim about this paper. What they are hoping to do is to get some bounds on electroweak scattering amplitudes, purely based on 3 assumptions: unitarity, analyticity and Lorentz invariance, something which would be interesting.

The assumptions they are making are standard assumptions about QFT, so if their bounds were violated it would be indication of a failure of our usual ideas about QFT. String theory is just completely irrelevant to what they are doing, note that the papers they are quoting to back up their calculations are not string theory papers. I suspect that if their bounds were actually experimentally falsified, what most string theorists would say is not that string theory has been falsified, but that QFT has been falsified, and that this implies one has to do string theory.

If their argument works, and you find violations of the bounds they promise to work out, the consequence would be that in one's high energy theory one has to give up Lorentz invariance, analyticity or unitarity. Unitarity is pretty fundamental to the whole idea of quantum mechanics, so people are unlikely to give that up. While perturbative string theory amplitudes in flat space have the assumed Lorentz invariance and analyticity properties, it is not at all clear that this is true of non-perturbative string theory, or of string theory in certain kinds of backgrounds. Some string theorists have speculated about Lorentz non-invariant backgrounds, and, as I mentioned in my posting, if non-perturbative string theory really does, as often claimed, involve getting rid of standard space-time, you quite possibly would also lose analyticity and/or Lorentz invariance.

Hmm, very, very interesting.

 

[marcus]

I think this passage that francesca quoted:

Boils down to four boolean propositions.
H: There is no light Higgs boson (how light they mean they don't say).
N: Physics is Analytic, Unitary and Lorentzian (N for "nice").
B: The bounds they calculate are violated.
F: String theory is falsified.

And the paragraph asserts that
H => (N AND B => F)
...

this is a clear and probably a fair outline of the reasoning in the paper. It seems to me to be an accurate straightforward paraphrase---although one has to leave room for Distler to suddenly jump up and say No that is not our argument! Maybe he would object to something (but I can't see what.)

In this case one has to point out that prop N can not be empirically verified. It is not something that one can OBSERVE.
Therefore the paper's argument does not provide a way to falsify string theory based on empirical observation.

Prop N is intriguing and appealing. My guess is that it is wrong but the main thing is that it is not something one can show is true by experiment. Physics is a human construct consisting of theories and many of these theories are at present formulated using mathematical models that are Lor. Invar. and Unitary and Analytic (in the sense of analytic functions of a complex variable). But not ALL theories are.

Also as a side comment keep in mind that parts of modern mathematics use functions which are NONanalytic, and operators which are NONunitary, and investigate symmetries which are modified Lorentz and depart from Lorentz invariance in some fashion.

It would be impossible to prove that Physics at the present moment is "Nice"----that is, that all the competing human theories use mathematics which is unitary, analytic, Lor invar. I think in fact that it is demonstrably false. I know of physical theories that have not been disproved which involve departures from exact unitarity (because of using a realistic quantum clock) and theories which use other classes of functions besides the analytic, and of theories which use a modified Lorentz invariance.

To prove that Physics is "Nice" one would have to falsify these theories, which has not been done. Also one would have to prove that no similar theories could ever be constructed in the future.

It seems that Prop N is not something that one can OBSERVE to be true, nor ought one decide arbitrarily to BELIEVE that it is true for subjective reasons such as that one simply feels attracted to it and likes it.

And therefore I conclude that the logical scheme of the paper, which selfAdjoint kindly outlines for us here, has no chance of proving F (i.e. falsifying string)
H => (N AND B => F)
because there is no way to verify N.

There could well be more controversy in store, so I plan to keep watching and maybe the picture will change.

 

[Chronos]

Agreed, marcus, and I agree with Peter. I have seen these smoke and mirror tactics too many times to be swayed by them. Conveniently ignoring observational evidence is . . . convenient.

 

[marcus]

Agreed, marcus, and I agree with Peter. I have seen these smoke and mirror tactics too many times to be swayed by them. Conveniently ignoring observational evidence is . . . convenient.

Chronos thanks so much for your agreement and support! However saying smoke and mirrors goes well beyond what I can do at the moment. I suspect Distler is dead serious and that he intends (after LHC has found no light Higgs) to hold the gun to the "nice" baby. He may be deluding himself but I suspect that he thinks he has a serious "proof" here of string validity. He can say "BELIEVE IN STRING
OR ELSE ACCEPT THAT PHYSICKS IZ NOT NICE!
And if we do not all bow our heads and accept string then he will shoot the baby and declare that Physicks must be not Analytick, or not Yoonitaree, or not Lorentziak.

I think that a statement like "Physics" is analytic Lorentz invariant unitary is a METAPHYSICAL type statement, not an empirical or observational one. The reality is that some of the theories which have so far not been experimentally falsified ARE and some are NOT. But about "Physics" we cannot observe if she is these things. Nevertheless I suspect that Distler imagines that he has a real argument involving empirical falsifiability, as his title indicates, and that he is SINCERE.

But so far this is just my hunch. I want to wait and see. He could, of course, NOT be sincere (as you suggest) and be doing smoke and mirrors. Or he could turn out to be right! Anything could happen so for now I think just watch and see how it plays.

 

[selfAdjoint]

Well Marcus, the last few comments on Woit's discuss N. Of the three components of N. Lorentz Invariance seems to be the shakiest, and also the one easiest to test experimentally, I can't imagine why you think it is "unobservable".

Much the same goes for Unitarity any violation of this would require the abandonment of the Born rule, which considering the trouble it has caused (hi Patrick!) would be a benefit in my view.

Analyticity doesn't mean the functions of physics are eveywhere holomorphic; the only everywhere holomorphic functions are constants! Singularities, such as the poles of meromorphic functions, their locations and their residues play a BIG role in physics. I believe a failure of analyticity would be a proof that the wave function was nowhere differentiable, or at least so throughout some open set in spacetime.

 

[marcus]

Well Marcus, the last few comments on Woit's discuss N. Of the three components of N. Lorentz Invariance seems to be the shakiest, and also the one easiest to test experimentally, I can't imagine why you think it is "unobservable".

Much the same goes for Unitarity any violation of this would require the abandonment of the Born rule, which considering the trouble it has caused (hi Patrick!) would be a benefit in my view.

Analyticity doesn't mean the functions of physics are eveywhere holomorphic; the only everywhere holomorphic functions are constants! Singularities, such as the poles of meromorphic functions, their locations and their residues play a BIG role in physics. I believe a failure of analyticity would be a proof that the wave function was nowhere differentiable, or at least so throughout some open set in spacetime.

I'm hip to the distinction between holomorphic and meromorphic---I tend to use the term "analytic" loosely to cover both cases---and also real analytic meaning that you can expand it in a powerseries most places.

I like the general tenor of your comment. And I am glad that people are discussing the extent to which one ought to expect physical theories to use series-expandable functions, and have normpreserving ("unitary") hibertspace operators do their time-evolution and so forth.

More power to them. Let them all discuss these issues. I am making a different point.

Physical theories can not be ultimately verified, only falsified and replaced by better. "Physics" I take to be the collection of theories which have not yet been refuted and discarded.
The statement "Physics is nice (unitar. anal. Lor)" is IMPOSSIBLE TO VERIFY.

IN ORDER TO USE IT IN THE distler SYLLOGISM you provided us, so as to logically falsify string (your statement F) you have to VERIFY niceness. It is not sufficient to be able to falsify statement N, "niceness".

I am very happy if people want to prove to us that physics is not necessarily Lorentz invariant. In fact that seems obvious to me because there are excellent physics theories like Freidel's spinfoam unification which are clearly NOT---they use a modified Lorentz invariance. And so on. Gambini and Pullin have an interesting way of proving physics can not have a unitary time-evolution. Gambini Pullin has not yet been falsified and neither has Freidel. So they are part of physics and they are not nice.

But simply proving that physics is not nice does not make the syllogism work. To get to your F you would have to VERIFY your N and your N can not be verified observationally. Even if it weren't obviously wrong (to a lot of us) it couldn't even in principle be verified observationally. It is a normative statement about the physical models that humans can construct and therefore metaphysics.

I do believe it is highly QUESTIONABLE metaphysics. But if someone stubbornly wants to believe that all human models of physical nature OUGHT to be unitar. anal. and Lor----then he will just go ahead and believe that. I can try persuasion and show examples of theories that are not and which achieve interesting results. But I don't see how I can design an experiment to demonstrate to him that physical theories do not OUGHT to be those things.

Am I missing something? It seems to me that to demonstrate to a steadfast believer I would have to do something like show that Freidel spinfoam is CORRECT. And that is something you cannot do with physical theories, you can only falsify them. If they pass this year then the next year's experiment can still show them wrong.

 

[Chronos]

Chronos thanks so much for your agreement and support! However saying smoke and mirrors goes well beyond what I can do at the moment. I suspect Distler is dead serious and that he intends (after LHC has found no light Higgs) to hold the gun to the "nice" baby. He may be deluding himself but I suspect that he thinks he has a serious "proof" here of string validity. He can say "BELIEVE IN STRING
OR ELSE ACCEPT THAT PHYSICKS IZ NOT NICE!
And if we do not all bow our heads and accept string then he will shoot the baby and declare that Physicks must be not Analytick, or not Yoonitaree, or not Lorentziak.

I think that a statement like "Physics" is analytic Lorentz invariant unitary is a METAPHYSICAL type statement, not an empirical or observational one. The reality is that some of the theories which have so far not been experimentally falsified ARE and some are NOT. But about "Physics" we cannot observe if she is these things. Nevertheless I suspect that Distler imagines that he has a real argument involving empirical falsifiability, as his title indicates, and that he is SINCERE.

But so far this is just my hunch. I want to wait and see. He could, of course, NOT be sincere (as you suggest) and be doing smoke and mirrors. Or he could turn out to be right! Anything could happen so for now I think just watch and see how it plays.

Since when has physics been nice? I reject nice physics out of hand. I'm an engineer, and convinced physics is cold and evil at heart. I watched a prototype machine run perfectly for 12 hours: almost without blinking. I then made the fatal mistake of taking a potty break. When I returned, it was laying on the floor in pieces.

I do not doubt Distler is sincere. But, it does appear to be a disengenuos argument with a splashy title. I see no new ideas, just spin doctoring.

 

[selfAdjoint]

I'm hip to the distinction between holomorphic and meromorphic---I tend to use the term "analytic" loosely to cover both cases---and also real analytic meaning that you can expand it in a powerseries most places.

I like the general tenor of your comment. And I am glad that people are discussing the extent to which one ought to expect physical theories to use series-expandable functions, and have normpreserving ("unitary") hibertspace operators do their time-evolution and so forth.

More power to them. Let them all discuss these issues. I am making a different point.

Physical theories can not be ultimately verified, only falsified and replaced by better. "Physics" I take to be the collection of theories which have not yet been refuted and discarded.
The statement "Physics is nice (unitar. anal. Lor)" is IMPOSSIBLE TO VERIFY.

IN ORDER TO USE IT IN THE distler SYLLOGISM you provided us, so as to logically falsify string (your statement F) you have to VERIFY niceness. It is not sufficient to be able to falsify statement N, "niceness".

I am very happy if people want to prove to us that physics is not necessarily Lorentz invariant. In fact that seems obvious to me because there are excellent physics theories like Freidel's spinfoam unification which are clearly NOT---they use a modified Lorentz invariance. And so on. Gambini and Pullin have an interesting way of proving physics can not have a unitary time-evolution. Gambini Pullin has not yet been falsified and neither has Freidel. So they are part of physics and they are not nice.

But simply proving that physics is not nice does not make the syllogism work. To get to your F you would have to VERIFY your N and your N can not be verified observationally. Even if it weren't obviously wrong (to a lot of us) it couldn't even in principle be verified observationally. It is a normative statement about the physical models that humans can construct and therefore metaphysics.

I do believe it is highly QUESTIONABLE metaphysics. But if someone stubbornly wants to believe that all human models of physical nature OUGHT to be unitar. anal. and Lor----then he will just go ahead and believe that. I can try persuasion and show examples of theories that are not and which achieve interesting results. But I don't see how I can design an experiment to demonstrate to him that physical theories do not OUGHT to be those things.

Am I missing something? It seems to me that to demonstrate to a steadfast believer I would have to do something like show that Freidel spinfoam is CORRECT. And that is something you cannot do with physical theories, you can only falsify them. If they pass this year then the next year's experiment can still show them wrong.

Well if you have a belief that nature is not Lorentz invariant, of course the caveat of Distler et al might seem disingenuous. But recall that those three properties - Lorentz invariance, unitarity, and analyticity, were the ones they used in deriving their resul, so it is REQUIRED for them to make that caveat.

And I just can't see it as metaphysics. My math background leads me to allow some slack to physics where the concept of proof is concerned, but physics proofs, like physics theories, can be well supported, and that's all we can expect in the real world, which always has the freedom to blindside us. Distler et al are consistent with other physics - not just SST in their caveat, and I don't think they need to be slammed as sly deceivers because of Popperiem or some personal doubts about the Lorentz transformations.

 

[marcus]

...And I just can't see it as metaphysics. My math background leads me to allow some slack to physics where the concept of proof is concerned, but physics proofs, like physics theories, can be well supported, and that's all we can expect in the real world,..

My math background probably does not prepare me to allow in quite quite the same fashion as you----I may allow more or less than you in different situations. But it is traditional to expect physics to run more on physical intuition and less on rigor----and to expect some formal expressions that are heuristic instead of well-defined---and to give benefit of doubt----compared to math.

I'm happy simply to disagree on this.

You misundertood me about "disingenuous". I said the opposite. I said I think Distler may be sincere. May actually think he has found a way to test string in a Popper way, so that it is "falsifiable" ( a word that Popper popplerized.)

By using a Popper word in his title, Distler walks into Popper's parlor and opens up a Popper discourse. I don't say he is being disingenuous (or using smoke mirrors as someone suggested). Rather I think he may be sincerely deluded, if he thinks he has found a falsifying test of string.

The operational test (that gives meaning to it all) is what do we see see string theorists do if suchandsuch is observed?

What actually has, in that case, been refuted?

What lines of research, what claims of promised explanation, do we see them abandon?

It might be interesting to know what you have in mind along these lines.

===================

Smolin has just come out with a paper about QG GENERIC PREDICTIONS with a discussion of the role that a new theory's predictions can play even before the theory is not completely worked out and is still a broad CLASS of theories.

I started a thread. Would very much appreciate your comment there.

He explicitly says, at the start, that he is talking about "soft" predictions and he doesn't say "falsify" LQG in a blanket way in the title. So you may find that the article is somewhat different in tone and spirit.
It is more seat-of-pants, but interesting.

He points out that some specific versions of QG can indeed be falsified, depending on which matter particles they predict. If they predict the wrong matter, out they go! but that is a minor part of the discussion towards the end.

the main burden is about generic "soft" predictions from a whole class of QG models.

Despite this difference, you might find parallels! which would be interesting.

 

[selfAdjoint]

I was just reading Smolin's new paper and got down to the section where he is giving his heuristic discussion in why Friedel and Levine found a length preserved as well as a speed in 2+1 LQG, hence DSR. And he asks what is the situation in 3+!? And I got bemused.

For what do we know about 3+1 GR that is not true of 2+1? Local excitations (of curvature, i.e gravity). 2+1 GR hasn't got any. And suppose we take a relational stance and ask what is preserved in local intractions between different frames? Evidently they have to have the same G.

So postulate a group of transformations that preserve c, h, and G (I have suggested this before). Automatically they preserve the Planck length. As G-> 0 and h -> 0 you retrieve classical SR. As c -> infinity and G -> 0 you have non-relativistic QM (Merriam relational version). If g-> 0 but h and c are measurably finite you get relativistic QM and RQFT. Only as you approach Planck energy levels do the full transforms become relevant.

It shouldn't be hard at all to define these 3-paprameter transformations so that they obey the appropriate limits. Call it twice-special relativity or TSR.

Well just an OT random thought, but I thought I'd share it. If inappropriate feel free to delete this post.

 

[marcus]

I was just reading Smolin's new paper and got down to the section where he is giving his heuristic discussion in why Friedel and Levine found a length preserved as well as a speed in 2+1 LQG, hence DSR. And he asks what is the situation in 3+!? And I got bemused.

For what do we know about 3+1 GR that is not true of 2+1? Local excitations (of curvature, i.e gravity). 2+1 GR hasn't got any. And suppose we take a relational stance and ask what is preserved in local intractions between different frames? Evidently they have to have the same G.

So postulate a group of transformations that preserve c, h, and G (I have suggested this before). Automatically they preserve the Planck length. As G-> 0 and h -> 0 you retrieve classical SR. As c -> infinity and G -> 0 you have non-relativistic QM (Merriam relational version). If g-> 0 but h and c are measurably finite you get relativistic QM and RQFT. Only as you approach Planck energy levels do the full transforms become relevant.

It shouldn't be hard at all to define these 3-paprameter transformations so that they obey the appropriate limits. Call it twice-special relativity or TSR.

Well just an OT random thought, but I thought I'd share it. If inappropriate feel free to delete this post.

I am reading Smolin's "Generic Predictions" too---his latest. It draws a lot of themes together (unification, matter degrees of freedom, a role for the cosmological constant with both large scale and small scale impact, speed of light increasing with energy...lots of things too many to mention)

I think one could usefully compare the papers' different approaches to prediction. Distler's paper is more concerned with showing string falsifiable---and thus a genuinely testable scientific theory. By contrast, in "Generic Predictions" Smolin seems concerned with something else besides falsification. He emphasizes "suprise"---maybe it is just the other side of the coin.

---quote---
...But theories triumph not because they do what is expected, but because of the surprises they lead to. A good theory must predict new phenomena, which are then observed. In the case of causal spin network theories we see several unexpected consequences which all have implications for experiment and observations. These are
• The symmetry of the ground state is DSR, leading to an energy dependent, parity even, speed of light.
• There is evidence that LQG predicts that spacelike singularities bounce. This opens up the possibility of tuning the parameters that govern low energy physics through a dynamical mechanism like cosmological natural selection (CNS)[53].
• These theories have emergent local degrees of freedom, hence they automatically unify geometry and matter.
• Disordered locality has consequences for cosmological observations because even at small levels that make it unobservable in local experiments it dominates in the early universe and at cosmological scales. A rough estimate of such effects shows that this mechanism has a possibility to naturally solve the horizon problem while predicting the correct spectrum of fluctuations of the CMB.
---endquote---

have to look at the issues again tomorrow when fresh

 

[selfAdjoint]

Marcus, I do wish you would get off this comparison and derogation of Distler's paper; it's not collegial and you have so many more worthy roles to play here. There is surely no lack of posters with obsessive agendas, and you have always been the breath of fresh air that blows away their cobwebs.

Before I go, I don't see how Distler can be called deluded since he did properly make his conclusion dependent on what we might call the LAU criterion - what I called above proposition N.

 

[marcus]

Marcus, I do wish you would get off this comparison and derogation of Distler's paper;.

my last post was meant to BE off. sorry you got the wrong impression.

I was worried that you were thinking your post was off topic, when you brought up Smolin's paper, and my point was that they were both about prediction but in two different ways----so one could compare WITHOUT saying that one's concern was better than the others.

Personally I think it is RIGHT to be concerned with making a theory predictive so that it can be falsified----and Distler can be commended for focusing on that.

the contrast is, to point out in this case that Smolin is dealing as he says at the outset with "soft" predictions which are generic to a class of theories. What new phenomena do these point to.

I absolutely did not mean to suggest that one approach was right and the other wrong. Probably one should have both.

Hard predictions that allow theories to be discarded if they don't pass the test.

Soft predictions of a more heuristic nature that inspire both theoreticians and experimentalists to think about, and look for, new phenomena.

(unifying electricty and magnetism suggested a new phenomenon, radio waves)

I think you misunderstood my last post, which was NOT derogatory to Distler, and admonished me unnecessarily. But I forgive you
(you have had plenty of other provocations, it must be admitted)

 

[marcus]

...So postulate a group of transformations that preserve c, h, and G (I have suggested this before). Automatically they preserve the Planck length. As G-> 0 and h -> 0 you retrieve classical SR. As c -> infinity and G -> 0 you have non-relativistic QM (Merriam relational version). If g-> 0 but h and c are measurably finite you get relativistic QM and RQFT. Only as you approach Planck energy levels do the full transforms become relevant.

It shouldn't be hard at all to define these 3-paprameter transformations so that they obey the appropriate limits. Call it twice-special relativity or TSR.
...

In case you might want to compare some other people's ideas of TSR
(I think similar to what you propose if maybe not exactly the same)

http://www.arxiv.org/abs/hep-th/0407080
Linear Form of 3-scale Relativity Algebra and the Relevance of Stability
C. Chryssomalakos, E. Okon
5 pages
Int.J.Mod.Phys. D13 (2004) 1817-1822
"We show that the algebra of the recently proposed Triply Special Relativity can be brought to a linear (ie, Lie) form by a correct identification of its generators. The resulting Lie algebra is the stable form proposed by Vilela Mendes a decade ago, itself a reapparition of Yang's algebra, dating from 1947. As a corollary we assure that, within the Lie algebra framework, there is no Quadruply Special Relativity."

http://www.arxiv.org/abs/hep-th/0406276
Triply Special Relativity
J. Kowalski-Glikman, Lee Smolin
13 pages
Phys.Rev. D70 (2004) 065020
"We describe an extension of special relativity characterized by three invariant scales: the speed of light, a mass, and a length..."

my comment: I think preserving a speed a mass and a length amounts to essentially the same as preserving c, hbar, and G.

 

[selfAdjoint]

In case you might want to compare some other people's ideas of TSR
(I think similar to what you propose if maybe not exactly the same)

http://www.arxiv.org/abs/hep-th/0407080
Linear Form of 3-scale Relativity Algebra and the Relevance of Stability
C. Chryssomalakos, E. Okon
5 pages
Int.J.Mod.Phys. D13 (2004) 1817-1822
"We show that the algebra of the recently proposed Triply Special Relativity can be brought to a linear (ie, Lie) form by a correct identification of its generators. The resulting Lie algebra is the stable form proposed by Vilela Mendes a decade ago, itself a reapparition of Yang's algebra, dating from 1947. As a corollary we assure that, within the Lie algebra framework, there is no Quadruply Special Relativity."

http://www.arxiv.org/abs/hep-th/0406276
Triply Special Relativity
J. Kowalski-Glikman, Lee Smolin
13 pages
Phys.Rev. D70 (2004) 065020
"We describe an extension of special relativity characterized by three invariant scales: the speed of light, a mass, and a length..."

my comment: I think preserving a speed a mass and a length amounts to essentially the same as preserving c, hbar, and G.

Thanks much for these links Marcus! I will pursue them. I am especially interested in that Lie Algebra angle.

Re the bolded comment, I agree, for let them be the Planck mass and length, and given c is preserved, you have two equations for G and h.