Quantcast
  • Register
PhysicsOverflow is a next-generation academic platform for physicists and astronomers, including a community peer review system and a postgraduate-level discussion forum analogous to MathOverflow.

Welcome to PhysicsOverflow! PhysicsOverflow is an open platform for community peer review and graduate-level Physics discussion.

Please help promote PhysicsOverflow ads elsewhere if you like it.

News

New printer friendly PO pages!

Migration to Bielefeld University was successful!

Please vote for this year's PhysicsOverflow ads!

Please do help out in categorising submissions. Submit a paper to PhysicsOverflow!

... see more

Tools for paper authors

Submit paper
Claim Paper Authorship

Tools for SE users

Search User
Reclaim SE Account
Request Account Merger
Nativise imported posts
Claim post (deleted users)
Import SE post

Users whose questions have been imported from Physics Stack Exchange, Theoretical Physics Stack Exchange, or any other Stack Exchange site are kindly requested to reclaim their account and not to register as a new user.

Public \(\beta\) tools

Report a bug with a feature
Request a new functionality
404 page design
Send feedback

Attributions

(propose a free ad)

Site Statistics

145 submissions , 122 unreviewed
3,930 questions , 1,398 unanswered
4,847 answers , 20,601 comments
1,470 users with positive rep
501 active unimported users
More ...

Analogy for the AdS/CFT Correspondence

+ 5 like - 0 dislike
115 views

Some time ago, I heard about a simple analogy for the AdS/CFT correspondence to something in everyday life. Consider a room filled with furniture, with the walls of the room covered in mirrors. The 2D mirrors we can think of as an N-dimensional CFT--the furniture is the corresponding entities in the N+1-dimensional AdS.

I feel like this is an over-simplification. What is lost in the actual AdS/CFT correspondence in this analogy? I feel like information in the 3D world is lost in the 2D mirror--is this true in the AdS/CFT correspondence? That is, is there information in the AdS that can't be expressed in the CFT?

This post imported from StackExchange Physics at 2015-06-05 09:23 (UTC), posted by SE-user Joshuah Heath
asked May 4, 2015 in Theoretical Physics by Joshuah Heath (60 points) [ no revision ]
The mirror won't tell you everything about the room. It can't tell you distances between objects, for example, and you will lose information if one object obstructs the view of another object. AdS/CFT is an exact equivalence. Knowing all observables in the boundary CFT lets you construct any observable in the bulk theory.

This post imported from StackExchange Physics at 2015-06-05 09:23 (UTC), posted by SE-user Andrew
Where did you hear about this? Is this analogy accurate ?

This post imported from StackExchange Physics at 2015-06-05 09:23 (UTC), posted by SE-user Prathyush
@Prathyush I don't remember exactly where--like I said in the post, it was quite some time ago. I think it was in some popular science magazine, and thus I was (and still am) somewhat skeptical about the accuracy of such an analogy. Nevertheless, it does raise the question of whether or not there is anything lost when going to the AdS, but if Andrew is right, then the AdS/CFT correspondence is an "exact equivalence", and thus nothing appears to be lost.

This post imported from StackExchange Physics at 2015-06-05 09:23 (UTC), posted by SE-user Joshuah Heath
@JoshuahHeath, I just want to know if any aspect of this analogy is even remotely correct.

This post imported from StackExchange Physics at 2015-06-05 09:23 (UTC), posted by SE-user Prathyush
@Andrew - just a thought about the accuracy of the analogy. Can't you tell the distance between objects by using the fact that there are two images (one on each side of the room)? To do this you'd need to know the size of the room, but this is encoded in the boundary data. This seems like a nice property of the analogy since then boundary data at separated points is encoded by passage through the bulk... It would be interesting to hear people's take on this!

This post imported from StackExchange Physics at 2015-06-05 09:23 (UTC), posted by SE-user Edward Hughes

1 Answer

+ 0 like - 1 dislike

The analogy is not perfect. In principle the AdS/CFT correspondence is exact, however the mirror analogy is not. It is well known in psychophysics that recovering the structure of a scene from a 2d image is an ill posed problem. There are may heuristics you can use to recover the shape and depth of objects based only on the projected image, and these usually give accurate enough results, but there is an infinite number of solutions, all compatible with the same image.

This post imported from StackExchange Physics at 2015-06-05 09:23 (UTC), posted by SE-user bruce smitherson
answered Jun 5, 2015 by bruce smitherson (-10 points) [ no revision ]
Is there anything about analogy that is actually correct?

This post imported from StackExchange Physics at 2015-06-05 09:23 (UTC), posted by SE-user Prathyush

Your answer

Please use answers only to (at least partly) answer questions. To comment, discuss, or ask for clarification, leave a comment instead.
To mask links under text, please type your text, highlight it, and click the "link" button. You can then enter your link URL.
Please consult the FAQ for as to how to format your post.
This is the answer box; if you want to write a comment instead, please use the 'add comment' button.
Live preview (may slow down editor)   Preview
Your name to display (optional):
Privacy: Your email address will only be used for sending these notifications.
Anti-spam verification:
If you are a human please identify the position of the character covered by the symbol $\varnothing$ in the following word:
p$\hbar$ysicsOve$\varnothing$flow
Then drag the red bullet below over the corresponding character of our banner. When you drop it there, the bullet changes to green (on slow internet connections after a few seconds).
To avoid this verification in future, please log in or register.




user contributions licensed under cc by-sa 3.0 with attribution required

Your rights
...