Has the use of the holographic principle of string theory in condensed matter physics silenced the skeptics?

Question

It seems to me that the use of string theory in calculations of strongly-interacting matter in condensed matter physics is an example of the theory being on the right track. And then there's the application of string theory to black holes. Have these quieted the skeptics? If not, what's the deal? Could a theory be used in making accurate calculations and still be wrong? Aren't the odds of that happening rather small?

This post imported from StackExchange Physics at 2014-04-11 15:50 (UCT), posted by SE-user Joebevo

Comments

Which skeptics?

This post imported from StackExchange Physics at 2014-04-11 15:50 (UCT), posted by SE-user user1504

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I meant the skeptics of String Theory.

This post imported from StackExchange Physics at 2014-04-11 15:50 (UCT), posted by SE-user Joebevo

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Yes, which ones?

This post imported from StackExchange Physics at 2014-04-11 15:50 (UCT), posted by SE-user user1504

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Do you mean this one for example? Such people would never ever be satisfied before they have achieved the goal of their "holy crusade"; which explicitely stated is makeing ST and everything related completely disappear from the landscape of allowed research directions ...

This post imported from StackExchange Physics at 2014-04-11 15:50 (UCT), posted by SE-user Dilaton

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Yes, I did have Peter Woit in mind. And perhaps Lee Smolin. I suppose the latter is a more balanced skeptic, although I have to admit I haven't read his views.

This post imported from StackExchange Physics at 2014-04-11 15:50 (UCT), posted by SE-user Joebevo

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Lee Smolin is at least not that destructive and unfair as PW as far as I know ...

This post imported from StackExchange Physics at 2014-04-11 15:50 (UCT), posted by SE-user Dilaton

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Why should applications to Condensed Matter physics, where string theory is essentially used as a mathematical tool, say anything about the correctness of string theory as a theory of quantum gravity (and more)? Not sure I follow the logic.

This post imported from StackExchange Physics at 2014-04-11 15:50 (UCT), posted by SE-user Heidar

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I'm only at a senior undergraduate level, so I don't know much about this. But naively speaking, if a theory postulates something (say, like a set of axioms), and the consequences of these postulates correspond to reality, then it seems to me that the theory is better off for it. Although, I suppose there COULD be multiple theories that satisfy the criteria. (I'm being more philosophical than scientific.) Again, I'm not sure quite how string theory is used in the context of CMPhy.

This post imported from StackExchange Physics at 2014-04-11 15:50 (UCT), posted by SE-user Joebevo

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@Joebevo Well, the whole AdS/CMT (and generalizations of it) are not really physical predictions of string theory, where you start with strings and at low energies derive standard model and continue to lower energies and describe non-relativistic electrons and superconductivity. In physics there exist many examples of two theories which are dual to each other. One important example is holographic dualities (gravity is non-local in a certain sense). The applications of string theory to condensed matter physics is essentially purely mathematical, and takes advantage of this duality.

This post imported from StackExchange Physics at 2014-04-11 15:50 (UCT), posted by SE-user Heidar

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Its not really a physical consequence of string theory as such. So I don't think it says so much about the correctness of string theory as a theory of "everything". But it indicates once more that the theory seems quit consistent and attractive, indeed! But as I discussed in my answer, the whole AdS/CMT business seems to be far from being under control and so far is of very limited use. This will hopefully change.

This post imported from StackExchange Physics at 2014-04-11 15:50 (UCT), posted by SE-user Heidar

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This question (v1) seems primarily opinion-based.

This post imported from StackExchange Physics at 2014-04-11 15:50 (UCT), posted by SE-user Qmechanic

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This question seems too opinion based to me and indeed it attracts after a nice one rather opinionated answers too ...

This post imported from StackExchange Physics at 2014-04-11 15:50 (UCT), posted by SE-user Dilaton

Answer 1

I know very little about this field, so please don't take my answer too seriously.

My impression is that, it's mainly string theorists who are excited about this line of research; condensed matter physicists are mostly skeptical (but many are following the field with interest). I guess the main reason is that these holographic calculations have not yet (as far as I know) given anything which is both new and impressive (from condensed matter perspective). But I have to add that, recently I have noticed papers using holographic methods with only conventional (and serious) condensed matter authors (say, this one). This might be a sign of slow acceptance by part of the condensed matter community...?

My impression is also that these holographic calculations are in no way under control (compared to the original Maldacena proposal) and relies on many layers of conjectures. Given a QFT, I don't think anybody knows how to systematically construct the gravitational dual. People just try to construct space times with the correct asymptotic symmetries (AdS, Lifshitz, Schrödinger, ...), try different matter configurations and then assume that the AdS/CFT dictonary is still valid.

They only try to say certain generic things about a big class of QFTs, using holographic methods, rather than calculate precise quantities for a very specific QFT. But these tools have potential to become very useful for non-perturbative physics if they come under control in the future.

But whether string theory can make precise and useful calculations for condensed matter physics, won't say anything about how correct it is as a theory of quantum gravity (or "everything"), as you seem to imply. What application to black holes do you have in mind? Microscopic calculations of black hole entropy? These calculations show that string theory is consistent as a theory of gravity (there are many other impressive calculations of this sort). Only few people would disagree on the impressive consistency of string theory and no alternative theory has been as successful in this regard. But consistency is not enough to declare a theory as correct.

This post imported from StackExchange Physics at 2014-04-11 15:50 (UCT), posted by SE-user Heidar

Answer 2

Well, it is not about "silencing skeptics"... first of all skepticism is not something bad. I am skeptic too... we are speaking about science not about belief systems. The ideas behind the holographic principle have been published, the world took notice and can continue to be skeptic... a publication is not a proof. Then, the "positive" results in condensed matter are not that positive after all... they are just particular cases and there are lots of violation of the holographic principle at least for the domains claimed to be valid too by some "believers". As a conclusion, the holographic principle has a rather limited area of applicability but is by far not as fundamental as some might believe...

This post imported from StackExchange Physics at 2014-04-11 15:50 (UCT), posted by SE-user user33923

Comments

Are your conclusions based on believe/disbelieve or do you have some deep technical knowledge about the topic...? This answer looks rather opinion than knowledge based to me, the same goes for the question too.

This post imported from StackExchange Physics at 2014-04-11 15:50 (UCT), posted by SE-user Dilaton

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Well, of course I can bring arguments. First of all, the holographic principle is a conjecture. It works for some interpretations of quantum gravity as a theory but we do not have a correct and complete formulation of quantum gravity. It is also based upon one interpretation of entropy (Beckenstein Hawking) and that is just an interpretation too. It counts only the degrees of freedom on the horizon. Is there nothing else inside? Is the only representation that exists the one on the surface? Cobordism in topology is one of the weakest characterizations but some appear to give it great value...

This post imported from StackExchange Physics at 2014-04-11 15:50 (UCT), posted by SE-user user33923