Holographic and trapped surfaces

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    Holographic Surfaces
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Discussion Overview

The discussion centers on recent developments in the understanding of holographic principles and area laws in general relativity, particularly through the works of Raphael Bousso and collaborators. Participants explore the implications of these theories for black holes, generalized holography, and the relationship between geometry and quantum theory.

Discussion Character

  • Exploratory
  • Technical explanation
  • Debate/contested

Main Points Raised

  • Some participants highlight Bousso's contributions to area laws in general relativity, referencing specific papers and conjectures related to quantum focusing and generalized entropy.
  • There is a discussion about the nature of holography, with one participant expressing uncertainty about how generalized holography relates to established theories like AdS/CFT, suggesting that Bousso bounds might have a dual form related to entanglement.
  • Some participants emphasize the importance of recognizing all authors in collaborative works, particularly in the context of Bousso's papers, while others debate the significance of authorship order in different fields.
  • One participant mentions a conjecture regarding a Generalized Second Law for cosmology, which posits that generalized entropy increases outside certain hypersurfaces, raising questions about its implications for black holes and cosmological models.

Areas of Agreement / Disagreement

Participants express differing views on the implications of Bousso's work and the nature of authorship in scientific publications. There is no consensus on the relationship between Bousso's bounds and established holographic principles, nor on the significance of the contributions of co-authors.

Contextual Notes

Some statements rely on specific assumptions about the nature of quantum gravity and the definitions of generalized entropy and holography, which remain unresolved in the discussion.

MTd2
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This the breaktrhough by bousso, which was a student from Hawking. It sees it was accepted under peer review magazines in 2 months. You can find the versions at:

1. arXiv:1504.07660 [pdf, other]
Proof of a New Area Law in General Relativity
Raphael Bousso, Netta Engelhardt
Comments: 15 pages, 10 figures; v4: conclusion of Theorem IV.2 strengthened
Journal-ref: Phys. Rev. D 92, 044031 (2015)
Subjects: General Relativity and Quantum Cosmology (gr-qc); High Energy Physics - Theory (hep-th)

2. arXiv:1504.07627 [pdf, other]
A New Area Law in General Relativity
Raphael Bousso, Netta Engelhardt
Comments: 4 pages, 2 figures; v3: typos fixed
Journal-ref: Phys. Rev. Lett. 115, 081301 (2015)
Subjects: High Energy Physics - Theory (hep-th); General Relativity and Quantum Cosmology (gr-qc)I really think this might yield for the solutions Hawings offer. But first take these papers into consideration: arxiv.org/abs/1506.02669

High Energy Physics - Theory
A Quantum Focussing Conjecture
Raphael Bousso, Zachary Fisher, Stefan Leichenauer, and Aron C. Wall
(Submitted on 8 Jun 2015)
We propose a universal inequality that unifies the Bousso bound with the classical focussing theorem. Given a surface σ that need not lie on a horizon, we define a finite generalized entropy Sgen as the area of σ in Planck units, plus the von Neumann entropy of its exterior. Given a null congruence N orthogonal to σ, the rate of change of Sgen per unit area defines a quantum expansion. We conjecture that the quantum expansion cannot increase along N. This extends the notion of universal focussing to cases where quantum matter may violate the null energy condition. Integrating the conjecture yields a precise version of the Strominger-Thompson Quantum Bousso Bound. Applied to locally parallel light-rays, the conjecture implies a Quantum Null Energy Condition: a lower bound on the stress tensor in terms of the second derivative of the von Neumann entropy. We sketch a proof of this novel relation in quantum field theory.
You can dare to identify the foliations defined by Bousso as related to mambrane paradigm. It's discussed here:

http://backreaction.blogspot.com.br/2015/09/more-about-hawking-and-perrys-new.html

There, you can find more links.

But I think consciously or not, the black hole is being hologramophied with matter, and we see what happens with it.
 
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I record for posterity that this was MTd2's 2000th post.

I wish I knew how to think about generalized holography. AdS/CFT was weird but one gets used to it: the physics in the AdS space, is equivalent to a different physics on its boundary.

But these Bousso bounds are for surfaces "in the interior". Also they don't involve a dual description... In the AdS/CFT case, a focus on *part* of the interior of the AdS space, can correspond to a truncation of the dual CFT. So it might be that Bousso bounds also have a dual form, as statements about entanglement in an underlying quantum theory from which space-time emerges...

I might even guess, that geometric symmetries of the emergent space-time, correspond to algebraic symmetries of the pre-space theory. And perhaps this could apply to the BMS group.
 
MTd2 said:
This the breaktrhough by bousso,

Hey, give Netta some credit. Authors on Hep-th papers are always listed alphabetically, unlike other fields where "first author" has some kind of meaning.
 
Ben Niehoff said:
Hey, give Netta some credit. Authors on Hep-th papers are always listed alphabetically, unlike other fields where "first author" has some kind of meaning.

Why should we? Non-first authors in other fields deserve credit too.
 
http://arxiv.org/abs/1510.02099

Generalized Second Law for Cosmology
Raphael Bousso, Netta Engelhardt
(Submitted on 7 Oct 2015)
We conjecture a novel Generalized Second Law that can be applied in cosmology, regardless of whether an event horizon is present: the generalized entropy increases monotonically outside of certain hypersurfaces we call past Q-screens. A past Q-screen is foliated by surfaces whose generalized entropy (sum of area and entanglement entropy) is stationary along one future null direction and increasing along the other. We prove that our Generalized Second Law holds in spacetimes obeying the Quantum Focussing Conjecture. An analogous law applies to future Q-screens, which appear inside evaporating black holes and in collapsing regions.
 

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