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B So the holographic principle doesn't have much evidence?

  1. Mar 8, 2016 #1
    I heard the holographic principle is a sham and that there is no evidence to back it up and that 99% of physicists don't accept the idea as credible.

    Is this true?
  2. jcsd
  3. Mar 8, 2016 #2


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    Its not so much that as the principle doesn't say as much as it might seem.

    Consider that (classically) you can via the dynamics map the 3 dimensional spatial information of "the universe right now" (as seen by some observational frame) into the 4-dimensional future. Hence the 4-dim space-time event history is "holographically" expressed this way. Now given relativity there's a spatial component to dynamics and we can likewise express 4-dim space-time history onto the boundary conditions over time which when you make time implicit seems to imply 3dim space is holograpically represented in 2-dim spatial boundary. There's also the null middle case where the 4-dim event history out side a BH's event horizon is "recorded" in the event horizon itself. But that event horizon is a 3-dim object. Topologically it is a spherical surface over "time" but that t coordinate happens to be null (null doesn't mean zero).

    The mistake, I believe in arguments beginning with discussions of the event horizon of a black hole is the assumption, simultaneously, of a stationary black hole and of in-falling "information" (with its requisite matter-energy) which will alter the event horizon of the black hole. Of course one is being a bit loose here and the not-quite stationary behavior is understood... or apparently so. But there are easy traps to fall into, exemplified by apparent paradoxes such as the BH info paradox. t'Hooft made a more complete analysis of Hawking's BH information paradox around these lines. (according to wikipedia). I would say it this way, one is not so much mapping to a 2-dim membrane but rather a 3-dim "thin" neighborhood of a 2-dim membrane when discussing BH's horizons encoding of infalling info. (Note this is also necessarily true of non-monochromatic actual holograms. One must use a photographic emulsion with some thickness rather than a simple planar pattern. So I'm still in a sense describing a holographic principle.)

    Now I don't know if my answer addresses your question as you did not give any specifics as to what you think the holographic principle says. So I'll listen out for further queries.
  4. Mar 8, 2016 #3


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    That is not the impression I get. There is a new paper actually by Hawking and two coauthors providing a hint towards the solution of the information paradox. It basically says that black holes actually have "soft hair" and is related to these asymptotic symmetries. I don't know much about the details but my friend explained a bit to me.

    In terms of the AdS/CFT correspondence, that really is just a duality between theories of gravity and gauge theories without gravity. It shows that in a certain situation these theories are essentially "the same" and you can relate what happens on either side to the other through some mathematical tools and using the equivalence of the two partition functions at the boundary. It provides you with a lot of insight conceptually.
  5. Mar 9, 2016 #4
    The problem with statements like 99% of physicists agree or disagree with... is that how would anyone know? What is current consensual thought is an individual assessment of the current research and peoples attitude to it. You can read papers in respected journals and on Arxiv but in the end the assessment is a personal one. After some time has passed a theory might reach some sort of general acceptance, but when that happens is anyone's guess.

    As for Holographic theory, it seems quite a few eminent scientists believe in it and if it is a scientist I trust I believe it too, but who is to say who is eminent and who isn't?

    All IMHO of course.
  6. Mar 9, 2016 #5
    so you think of it as like a 3d object/anomaly compressed into an almost 2d like size/state?

    sorry if im getting the wrong impression, im in a little over my head here but i like how you dont talk down to me

    do you know of studies supporting this hypothesis?

    i was saying the exact same thing before [person], its all opinion and you can gain alot of knowledge by asking people rather than just googling the mainstream answer! so many different views of real people, its much more interesting.
  7. Mar 10, 2016 #6
    Chrisjohnson, you should start from the beginning not from the end. There is much to learn in terms of established facts and science before jumping onto the speculative stuff imo.
  8. Mar 10, 2016 #7


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    The norm in this forum is to provide a link to a suitable reference (when asking something as generic as your question), so that there is something specific to discuss. If you are linking to a popular science article, you should include the underlying scientific references too (rather than leave to others to look it up).

    Could you pass that on, please.
  9. Mar 10, 2016 #8


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    It is one thing to claim that bulk theory and boundary theory are closely related, and another to claim that they are completely equivalent to each other. There is no doubt that the former is true, but the latter is still far from being proven.
    See also http://lanl.arxiv.org/abs/1507.00591
  10. Mar 11, 2016 #9


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    In the case of AdS/CFT (the first example of a higher dimensional object to clearly exhibit gauge gravity duality) that is definitely true. They are nowhere near to proving the correspondence is rigorous. However, people shown that it works for a lot of different things and produces very sensible, physical results (basically the best hope of proving it is by brute force). Many of these results for strongly coupled QFTs are things that people are typically unable to do by other methods.

    For example, it shows that in terms of transport problems that you can reproduce the results using hydrodynamic methods in that limit. That intuition comes from the fluid gravity correspondence. You can calculate these things in the deep IR on the horizon and match them to the boundary UV CFT. You can calculate the lower viscosity bound, which actually is very low and has been observed in the RHIC. The correspondence also naturally encodes the Wick rotation in the metric and the dissipative dynamics of many strongly correlated systems.

    If you put fermions into the charged RN black hole, specifically for the RN metal, that depending on the charge to mass ratio you can get Fermi surface like objects. This also also provides very interesting things like "hairy" black holes from bulk fields and also shows you can have spontaneous discharge from the production of these mesons/mesino pairs.

    The things that I find very beautiful about the correspondence is that it basically shows you that the gravity problem and the gauge theory are the same thing. You don't see the QFT gauge fields in the gravity side (I say this carefully because you do have "gauge" fields in the bulk, but they correspond to global symmetries on the boundary). From the gravity side you basically get all the things like the Ward identity in QFT for free which is great evidence for this. In this way, the correspondence is indeed very physical. Before I studied it many people made it sound like witchcraft, but I would argue it is most definitely not.
  11. Mar 11, 2016 #10
    Well I didn't hear it from a well respected physicist or anything, it's just my friend who's teacher in physics 101 (or whatever) told him that the holographic principle was completely inaccurate and has little to no evidence to support it.

    I am not planning on taking classes but physics still interests me and based on the little research i did on this (because it was interesting) it's supposed to be a legitimate theory accepted by many people.

    Im just wondering if that's right, wrong, or undetermined. A short elaboration is welcome but I don't want any of you to waste your time with extremely technical explanations because I don't have the time or energy to interpret it.
  12. Mar 12, 2016 #11


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    The simplest answer is - undetermined. There are good reasons to think it might be right, but also there are good reasons for not being convinced.
  13. Mar 13, 2016 #12
    Thank you, perfect answer.
    I'm going to go look into this more.

  14. Mar 13, 2016 #13
    It's a theory and as such it is not inaccurate and certainly not completely inaccurate. It is accurate in the sense that there are some axioms and some assumptions and from these it makes sense.
  15. Mar 13, 2016 #14
    So more or less the evidence is solid and even the assumptions based on the evidence are more than likely solid as well.

    Just like the "theory" of evolution.

  16. Mar 13, 2016 #15
    I should mention the word theory does not mean its normal definition in scientific context.

    The definition in that area is "a comprehensive explanation of some aspect of nature that is supported by a vast body of evidence."
    (Source: http://www.nas.edu/evolution/TheoryOrFact.html)
  17. Mar 14, 2016 #16
    Yes haha I'm aware...

  18. Mar 15, 2016 #17
    There's no sham. The holographic principle is property of string theories. I'd suggest you start with the easier question of - 'what is the evidence to support string theories?'.

    Whether 99% of physicists accept the holographic principle as credible is a very misleasing statement, for two reasons, no such survey of physicists has been conducted, secondly to understand the holographic principle requires highly specialised understanding of theoretical physics, which very few physicists have. As a ballpark estimate, I would say that only about 1% of physics graduates actually go on to the prerequisite subject matter in order to properly understand the holographic principle.

    For the purposes of training your own critical thought, and that of your friend, I think it would be useful to go back the source of your information and examine it more carefully. I suspect that what actually happened was that your friend raised the subject of the holographic principle in an beginner physics class and was offered direction towards understanding the basics first. There's also no particular reason to believe that someone teaching a 'Physics 101 class' would have a strong understanding of the holographic principle.
    Last edited: Mar 15, 2016
  19. Mar 15, 2016 #18


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    I requested Chris provide this, but so far he has not. How can we rationally discuss something someone "heard" ?
    Last edited: Mar 15, 2016
  20. Mar 15, 2016 #19
    Fair enough

  21. Mar 17, 2016 #20
    told you my teacher said it. we went over this. you can ask her for her sources.
  22. Mar 18, 2016 #21


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    No, we can't, because she's not the one posting here, you are. Please review the PF rules for sources.

    In any case, the original question has been adequately answered. Thread closed.
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