# Black-hole firewall and holographic principle

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Can the firewall be viewed as the holographic boundary? Naively a hologram 3d image can not cross the hologram 2d surface that produces that image. According to the metaphor the boundary - 2d field quantum theory without gravity - could act as a firewall for the enclosed space - 3d string theory with gravity and black holes. Yet information won't be lost by the presence of the firewall, because the digital bits would be just the pixels of that firewall/boundary. Doesn't this settle the paradox of entanglements non-locality with quantum gravity? " we must carefully impose the laws of thermodynamics and/or statistical physics to Maxwell's Demon himself and when we do so, his miraculous abilities to create a paradox evaporate." In the same way I'm asking to impose the boundary S matrix unitarity to the firewall ;-) The entangled partner behind the firewall is then a kind of fictitious hologram according to the Wheeler DeWitt diffeomorphism of quantum gravity, isn't it?

This post imported from StackExchange Physics at 2014-03-07 13:38 (UCT), posted by SE-user user2829483
asked Oct 28, 2013
I don't understand people downvoting a question without commenting

This post imported from StackExchange Physics at 2014-03-07 13:38 (UCT), posted by SE-user user2829483
I'm not one of the downvoters, but I do think the question shows a lack of effort. There is lots of stuff around about firewalls, and if you spent some time working through it you would answer your own question. Much of it is hard of course, but for example Joe Polchinski's talk at youtube.com/watch?v=tEtt4A7WsDg would be a start.

This post imported from StackExchange Physics at 2014-03-07 13:38 (UCT), posted by SE-user John Rennie
I disagree that someone could answer this question just by studying what experts say about firewalls. It requires some understanding of the holographic principle, maybe the membrane paradigm for black hole event horizons, and other concepts. I will answer if I can think of a reasonable thing to say.

This post imported from StackExchange Physics at 2014-03-07 13:38 (UCT), posted by SE-user Mitchell Porter
@Mitchell Porter: Thanks for your comment and your help. Below I tried to find an answer by myself, but I agree with you: for sure it is incomplete because I should better understand the holographic principle. In fact also the article I quoted is using the "effective field theory" instead of the complete "quantum field theory" as per my original question...

This post imported from StackExchange Physics at 2014-03-07 13:38 (UCT), posted by SE-user user2829483
@MitchellPorter: Maybe, but what is the question even asking? The firewall supposedly is at the event horizon, isn't it?

This post imported from StackExchange Physics at 2014-03-07 13:38 (UCT), posted by SE-user Dimensio1n0
Thanks for your vote. I've read your question about the holographic principle, the correction of Mitchell Porter on the blog post and the answer of Joshphysics that you accepted. So we have a bulk quantum gravity or scattering amplitudes (S Matrix) for strings in AdS that is equivalent to correlation functions in momentum space of CFT, with general covariance where H vanishes

This post imported from StackExchange Physics at 2014-03-07 13:38 (UCT), posted by SE-user user2829483
We should consider the entire solution to the Wheeler deWitt equation if we are to understand the physics of black holes

This post imported from StackExchange Physics at 2014-03-07 13:38 (UCT), posted by SE-user user2829483

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First we need to discuss what is meant by a boundary.

Consider a rectangular sheet of paper. The boundary of the whole sheet is a rectangle, the edge of the paper. It's where the paper ends.

Now draw a circle on the sheet of paper. The circle is the boundary of a disk-shaped region of paper inside the circle, but the paper doesn't stop there. This boundary has an outside as well as an inside.

The firewall, if it existed, would be like the boundary of the circle. But holographic duality involves the edge of the paper. The dual field theory describes everything on the sheet of paper, not just what happens inside the circle.

This post imported from StackExchange Physics at 2014-03-07 13:38 (UCT), posted by SE-user Mitchell Porter
answered Nov 1, 2013 by (1,850 points)
Perfect! You understood my question. Now I ask you a favor: take some scissors and cut the circle off the paper so that now there is an hole in the paper, so that now the circle is also an edge or a boundary of the paper. Can you now apply the holographic principle also on that circle? If you show me that that is wrong I will mark this as answered

This post imported from StackExchange Physics at 2014-03-07 13:38 (UCT), posted by SE-user user2829483
Hmm. I believe the original idea of black hole complementarity was that everything behind the event horizon is dual to degrees of freedom which pile up just outside the horizon, and then get re-radiated. So in the second picture, the Hawking radiation doesn't come from the other side...

This post imported from StackExchange Physics at 2014-03-07 13:38 (UCT), posted by SE-user Mitchell Porter
If such a picture were true, rather than being an addendum to holographic duality on the boundary, I think it would be just a possible redescription of the "bulk" theory. That is, you wouldn't have a new boundary theory which was defined on "rectangle+circle" (edge of space but event horizon)...

This post imported from StackExchange Physics at 2014-03-07 13:38 (UCT), posted by SE-user Mitchell Porter
However, I am somewhat skeptical of this picture (original BHC), and very skeptical of firewalls. The recent papers by Papadodimas and Raju look more plausible to me - no firewall, the AMPS paradox is avoided by a nuance of how the boundary theory describes the black hole interior...

This post imported from StackExchange Physics at 2014-03-07 13:38 (UCT), posted by SE-user Mitchell Porter
But I also liked Mathur's fuzzball concept, which could imply that the black hole is generically an extended object reaching out to the horizon - that even with a giant black hole, the event horizon isn't just homogeneous empty space on either side...

This post imported from StackExchange Physics at 2014-03-07 13:38 (UCT), posted by SE-user Mitchell Porter
It might be best if we created a room on chat.physics.SE or otherwise had a dialogue about these topics.

This post imported from StackExchange Physics at 2014-03-07 13:38 (UCT), posted by SE-user Mitchell Porter
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I found the answer here where they say

We present a further argument that typical black holes with field theory duals have firewalls at the horizon.

And I've also found the following notes inside:

Gauge/gravity duality in its various forms [1, 2] provides a construction of quantum gravity in spacetimes with special boundary conditions. This construction is algorithmic, following from that [3] of the dual field theory (DFT).

...

In §2 we present an argument that, without other significant departures from effective field theory (EFT), typical black holes must have firewalls at their horizons.

....

In §5 we argue that the usual calculation of the Hawking flux is valid even with the firewall. ...

This post imported from StackExchange Physics at 2014-03-07 13:38 (UCT), posted by SE-user user2829483
answered Oct 31, 2013 by (5 points)
This is a research topic. There are newer papers stating that there is no need of firewalls. see for example motls.blogspot.gr/2013/10/… and links therein. One has to have strong mathematical background to wade into this.

This post imported from StackExchange Physics at 2014-03-07 13:38 (UCT), posted by SE-user anna v
Thank you very much for your comment. Hopefully I'm not wading into this if I just add the following note "one will have to accept either state dependence or firewalls as an integral part of quantum mechanics in the presence of black holes" from physics.aps.org/articles/pdf/10.1103/Physics.6.115 "What’s Inside a Black Hole’s Horizon?". Thanks again

This post imported from StackExchange Physics at 2014-03-07 13:38 (UCT), posted by SE-user user2829483
Looking at that site you can find also some bitter comment about Matt Strassler and also about Emilio Pisanty, one of the experienced person who [put on hold] my question. Just as an example of "wading into st": motls.blogspot.it/2012/10/in-awe-about-entanglement.html where you can read: "For example, take this Emilio Pisanty guy, a Mexican currently in London who studies some "quantum dynamics"... In quantum mechanics, entanglement and correlation is the very same thing. "Those old children don't want to hear anything of the sort."

This post imported from StackExchange Physics at 2014-03-07 13:38 (UCT), posted by SE-user user2829483
@user2829483 you can find also some bitter comment about Matt Strassler and also about Emilio Pisanty No news, you can find bitter comments about almost everyone there.

This post imported from StackExchange Physics at 2014-03-07 13:38 (UCT), posted by SE-user jinawee
Sure thing :-) I don't know if this Hilbert space of comments is separable but just now I've noticed from the Oxford dictionary that using the word comment as uncountable could imply a slight difference in the meaning... Sorry if I was unclear and thanks to you all

This post imported from StackExchange Physics at 2014-03-07 13:38 (UCT), posted by SE-user user2829483

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