What is Holographic principle: Definition and 60 Discussions

The holographic principle is a tenet of string theories and a supposed property of quantum gravity that states that the description of a volume of space can be thought of as encoded on a lower-dimensional boundary to the region—such as a light-like boundary like a gravitational horizon. First proposed by Gerard 't Hooft, it was given a precise string-theory interpretation by Leonard Susskind, who combined his ideas with previous ones of 't Hooft and Charles Thorn. As pointed out by Raphael Bousso, Thorn observed in 1978 that string theory admits a lower-dimensional description in which gravity emerges from it in what would now be called a holographic way. The prime example of holography is the AdS/CFT correspondence.
The holographic principle was inspired by black hole thermodynamics, which conjectures that the maximal entropy in any region scales with the radius squared, and not cubed as might be expected. In the case of a black hole, the insight was that the informational content of all the objects that have fallen into the hole might be entirely contained in surface fluctuations of the event horizon. The holographic principle resolves the black hole information paradox within the framework of string theory.
However, there exist classical solutions to the Einstein equations that allow values of the entropy larger than those allowed by an area law, hence in principle larger than those of a black hole. These are the so-called "Wheeler's bags of gold". The existence of such solutions conflicts with the holographic interpretation, and their effects in a quantum theory of gravity including the holographic principle are not fully understood yet.

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  1. S

    I Holographic principle in continuous spacetime?

    Can the holographic principle be applied to spacetimes and metrics that are (fundamentally) continuous/smooth? Or only to discrete ones?
  2. S

    I Multiple (Non-Interacting) Universes?

    Before anything, I would like to clarify that I am aware that this is speculative physics more than established mainstream physics (and Smoot is not claiming that his ideas are true). However I think that it is interesting to discuss these models even if they are not yet proven to be right. I...
  3. S

    I How many apparent horizons could the Universe have?

    I was reading a paper written by George Smoot [1], which assumes the holographic principle as true and conjectures that our universe would be encoded on the "surface" of an apparent horizon as the weighted average of all possible histories. In that way, there would be one world (or universe)...
  4. geshel

    I Holographic Principle and/or implications of the entropy bound

    Hi all, First post here. I'm a casual physics enthusiast, but I've been reading and thinking a lot about this topic lately. The thing I'm most interested in is the fact that black hole formation involves the simultaneous limits of two things: time dilation and the information bound. I find it...
  5. H

    A Holographic principle (I'm looking for a paper that I read)

    I read a paper a long time ago. And i forgot who wrote it. The author said that information was not encoded on space time but on the boundaries of regions of space time. there was 3 parts on this boundaries. a space like part (for the initial conditions) . another one for the "out" state...
  6. BiGyElLoWhAt

    B Searching for a Lost PhD Thesis on Black Holes

    The paper is reasonably old and was written as a phd thesis by (I believe) a man from china. It was basically the first paper on the subject and in it he effectively (from what I understand) dropped particles into a black hole, counting the information added, and saw that the black hole changed...
  7. nomadreid

    I What use is the AdS/CFT correspondence in a flat universe?

    All the accounts which I have read (and which are accessible to my limited knowledge of General Relativity and its mathematics) on the holographic principle says vaguely that the AdS/CFT correspondence is very enlightening, but with the caveat that, well, we don't happen to live in an AdS space...
  8. S

    A Is the Randall-Sundrum model background independent?

    Randall-Sundrum model (https://en.wikipedia.org/wiki/Randall%E2%80%93Sundrum_model) is related to string theory. String theory can be background independent (https://en.wikipedia.org/wiki/Background_independence): "String theory is usually formulated with perturbation theory around a fixed...
  9. S

    I Is the holographic principle based on fuzzy logic?

    Physicist Craig Hogan has proposed that the universe is based on holographic principle. To prove that the universe is a "hologram" he (and other physicists) have designed an experiment named "The Holometer" to measure quantum fluctuations that would become fuzzy at Planck scale...
  10. S

    A How does this study affect the holographic principle?

    In a recent study (https://phys.org/news/2018-08-flaw-emergent-gravity.html) it has been discovered an important flaw in Emergent/Entropic Gravity because it has been discovered that holographic screens cannot behave according to thermodynamics... But then, doesn't this also invalidate...
  11. nomadreid

    I ER=EPR baby steps: causation or not?

    The questions concern the extension of the holographic principle to the identification of a wormhole between two black holes with negative cosmological constant and an entangled pair on its boundary, included in the conjecture known as EPR=ER ( Maldacena, Susskind). I refer to...
  12. S

    A Could information in a boundary be modified once encoded?

    Could information in a boundary be modified once encoded in holographic principle?There are models of universes where holographic principle has a different correspondence (there is absolutely no reason to assume that this would hold true for all possible universes. You could have a universe...
  13. S

    A What does this article mean? (The holographic principle and M-cosmology)

    I was reading an article about holographic principle and M-cosmology and how could they be used to interpret QM mechanics. But there's a part where it talks about holographic principle in a strange way to me. What does this article mean with this?: "Since for the participant observer the...
  14. S

    A Information encoding in the Holographic principle

    Can whatever type of information be encoded in a boundary in holographic principle? in a question some years ago regarding holography (https://physics.stackexchange.com/questions/75436/are-stokes-theorem-and-gausss-theorem-examples-of-the-holographic-principle) It is said that AdS/CFT is the...
  15. .Scott

    I Event Horizons - Holographic Principle

    Another thread (now closed), got me thinking about the holographic principle. So I looked it up and found a couple of surprises. First it seems to be attached in some peculiar way to string theory. Second, it seems to be applied more restrictively than it I thought. It's especially that...
  16. S

    A Can a 3d holographic universe exist in 3d?

    In a holographic universe model, could our 3D universe be encoded in 3D and still be a holographic universe, instead of 3D information encoded in 2D space? Or is the standard model (non-holographic) of the universe already 3d information encoded into 3d space...
  17. Michael27

    B Can the Holographic Principle make predictions

    I have been following the online lectures of Leonard Susskind regarding the holographic principle and entanglement.see Holographic Principle Lecture Part2 The universe can be seen as two-dimensional information on a cosmological horizon. (see https://en.wikipedia.org/wiki/Holographic_principle)...
  18. nomadreid

    I Holographic principle versus no-cloning

    If I understand the holographic principle for black holes correctly (which is highly unlikely, but this is a start), the information of a particle falling into a black hole is encoded on the event horizon. But from the view of General Relativity, the particle will not notice a change upon...
  19. FallenApple

    A Argument for Holographic Principle

    So around 44:00, Susskind begins his argument. He put a variety of items into a region of space, and the added a minimal shell of material surrounding the items, then squeezed that material to form a black hole around the item. Then he said that the amount of original information cannot be...
  20. J

    Cosmology Book on Black Holes, Strings, AdS/CFT

    Hello, I would really like a book like Susskind's "An Introduction To Black Holes, Information And The String Theory Revolution: The Holographic Universe" but not so condensed. If you have anything to suggest please do so. Also, if you know of any book that contains any part of the above book in...

    B Is it possible Earth is a black hole?

    Yes I know. Sounds silly. I'm not a physicist, but it occurred to me to wonder: is it possible Earth is a black hole with data encoded in two dimensions on its surface? What would the proofs look like? Discuss.
  22. Buzz Bloom

    I Is the Holographic Principle the Key to Understanding Our Universe?

    I have just come across the following on the Astronomy Picture of the Day. https://apod.nasa.gov/apod/ap170423.html Here is a quote that I would like to learn more about. The Holographic Principle, yet unproven, states that there is a maximum amount of information content held by regions...
  23. FallenApple

    I How does the Holographic Principle relate to 11 dimensions?

    So the Holographic Principle says that our 3 dimensonal world is encoded in the 2d surface of the cosmological horizon. What about the remaining dimensions? Are they there in the regular 3space or are they also encoded?
  24. A

    I Holographic principle, non-locality, and Lorentz invariance

    Hi all, Some recent comments from the forums here led me to do a bit of reading on the holographic principle, and to a posting on "The Reference Frame" by Lubos Moti about the (likely lack of) 'holographic noise' in the experiment by Craig Hogan at Fermilab...
  25. M

    I Holographic Principle discussion in Sean Carroll's book

    am reading Sean Carroll's pop-science book 'From Eternity to Here' and am having trouble connecting the links in his discussion of the Holographic Principle. At the outset, I would ask that you try to answer in terms of Carroll's discussion and without moving into concepts much more advanced...
  26. C

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

    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?
  27. ohwilleke

    LQG has not been shown to violate the holographic principle

    Backreaction has the story: http://backreaction.blogspot.com/2015/09/no-loop-quantum-gravity-has-not-been.html debunking this article: Violation of the Holographic Principle in the Loop Quantum Gravity Ozan Sargın, Mir Faizal http://arxiv.org/abs/1509.00843 and also showing the authors behaving...
  28. K

    Is there a holographic principle in loop quantum gravity?

    for example, is loop quantum gravity/SF in 4 dimensions dual to a CFT in 3 dimensions? does a serious proposal of QG have to respect the holographic principle?
  29. I

    Holographic Principle question

    So I've been looking up things on the Holographic Principle for a while now, but there's still a few questions I have. As I understand it, the Principle says that if I drop a book into a black hole the book's information would be 3D inside the black hole and it would also be 2D on the event...
  30. M

    Holographic principle and string theory

    Hi. I am no physicist but I am trying to know something about the holographic principle. As I understand, everything is happening in a surface and our three-dimensionality is an illusion of our senses. On the other side, string theory assume the existence of 11 dimensions. Are the two theories...
  31. Nim

    How does the Holographic Principle apply to different scenarios and dimensions?

    I first came across this concept in a Scientific American magazine. At the time it was nigh impossible to find much more information on it. Even now I am having a hard time wrapping my head around it. So I have a few questions. From what I understand, it basically says: Every single bit of...
  32. I

    Holographic Principle Projection

    Hi. I have a question about the Holographic Principle. I've been looking up things about it for a while now, and I think I understand it. The total content of a space is propositional to the area surrounding it and not the volume. The thing I'm having trouble with is how everything seems 3d...
  33. S

    Holographic principle in reverse

    I'm getting a rough idea of the holographic principle relating the shannon entropy of a boundary surface to the thermodynamic entropy contained within the bounded volume. So far as I understand the primary claim is that the total information needed to describe the entirety of the internal...
  34. M

    Susskind process and holographic principle

    Why is it that Susskind in describing the holographic principle - why is it that he considers a quantized universe?
  35. T

    Holographic principle, mathematical universe & dimensional reduction

    If the holographic principle says that the the observable universe could be represented as a two dimensional surface, and we accept the idea that the universe is itself a mathematical object, and cantor showed that we could in some cases represent higher dimensional sets within lower dimensional...
  36. L

    Can the Holographic Principle Explain All Physical Information in a Surface?

    What is the reason/ explanation (possibly in a nutshell!) that all the physical information of a volume can be encoded in the surface surrounding that volume?Because, you know, that sounds silly, at first! I browsed some introductory sources, but could not find any quick answers. Also, if...
  37. nomadreid

    In holographic principle, the boundary is wrt which light cone?

    It is stated that in the holographic principle (e.g., in http://en.wikipedia.org/wiki/Holographic_principle) that the the description of a volume of space is encoded on a light-like boundary to the region. But with respect to which position in the volume? In a black hole, it is clear, because...
  38. L

    Does the holographic principle remove the need for dark matter

    I appreciate that the holographic principle is just a theory, but if I accept it and the related aspects of string theory, does it do away with the need for dark matter (since I think that the mass approaches infinity as one changes the reference frame in which one observes the the mass)...
  39. D

    Holographic Principle: Quantum Gravity & String Theory

    Hi All, :smile: 1. Is it a property of all quantum gravity theories? 2. Do all string theorists and not just Susskind, Maldacena, t'Hooft, believe HP to be property of string theory? 3. As most prominent basis for Holographic Principle is associated with dependence of Black Hole Entropy...
  40. S

    Holographic principle and conservation of energy

    Hi PF! I was wondering, if the holographic principle (from string theory) really can be true. I see some physical flaws in the way it works. Here is why: Suppose that the second law of thermodynamics is true. It states that for any system, the multiplicity of the system must increase, ergo...
  41. T

    Question: Greene's The Hidden Reality : the holographic principle

    Question: Greene's "The Hidden Reality": the holographic principle On pp. 260-261 of "The Hidden Reality" Brian Greene says the following: I puzzled over this for quite awhile and it seems as though Greene, probably inadvertently, phrased this somewhat more decisively than is justified - that...
  42. haael

    Holographic principle as an answer to few mysteries

    Some time ago I had finished the book "The Black Hole War" by Leonard Susskind. I was impressed about the idea of explaining 2 phenomenons as a consequence of the holographic principle. We all here know what the holographic principle is. The maximum amount of information in some region of...
  43. L

    Exploring the Holographic Principle: Questions and Answers

    Hi,I don't understand the holographic principle,how can the entire physics in a space be done on its boundary,arent we supressing a dimension and there by losing the information contained in it?,and is it neccesary that the boundary be closed?
  44. C

    Lack of quantum fluctuations rules out holographic principle ?

    Recent searching of the light from the quasars indicate lack of the quantum fluctuation of the spacetime. http://arxiv.org/PS_cache/arxiv/pdf/1108/1108.6005v1.pdf Does it mean the lack of quantum foam rules out the discretness of the spacetime too ? How to explain Casimir effect and...
  45. J

    Does the holographic principle imply that the Universe has a Schwartzchild radius?

    I understand that the holographic principle applies to black holes and states that they are objects of maximum information/entropy. It states further that this information/entropy is bounded by the black hole's area rather than its volume. Apparently the holographic principle might apply to...
  46. Pengwuino

    Holographic principle and entropy mapping of a BH

    I've just started reading up on the holographic principle and eventually want to work my way to figuring out what Verlinde has proposed using it for. One thing I've noticed in a couple of papers is the mapping of the entropy of a black hole onto a holographic screen. Why are families of light...
  47. C

    Holographic Principle and missing Antimatter

    QCD does not violate the CP symmetry as easily as the electroweak theory; unlike the electroweak theory in which the gauge fields couple to chiral currents constructed from the fermionic fields, the gluons couple to vector currents. Experiments do not indicate any CP violation in the QCD sector...
  48. I

    Quantum Uncertainty in the Holographic Principle

    Hi all, A question about the Holographic Principle. I've recently started reading up about this, and watched Bousso's neat introductory video . I thought, "Ah, this is so refreshingly simple!", and proceeded to write down my own notes. However here things revealed themselves to be not...
  49. C

    The holometer - experimentally testing the holographic principle?

    "The holometer"-- experimentally testing the holographic principle? Several popular-science type news sources are reporting this weekend on an experiment at Fermilab that claims to experimentally test the holographic principle.. Popsci then says a bunch of vague stuff that sounds like they...
  50. C

    Is Holographic Principle a confirmed theory ?

    Gerard 't Hooft proposes the dimensional reduction, Leonard Suskind uses the Holographic Principle in String Theory, Juan Maldacena wrotes AdS/CFT correspondence. There are hundreds articles in 2010 since Erik Verlinde wrote its "Origin of the gravity". Many astronomical phenomenons like Dark...