Is the firewall explained by the Penrose interpretation?

[T S Bailey]

The firewall has been proposed to explain why entanglement monogamy isn't violated in the AMPS thought experiment. The firewall is hypothesized to break the entanglement between the particle pairs of Hawking radiation created near the horizon so that the total sum of radiation emitted by the black hole can be maximally entangled. However, if the Penrose interpretation is correct then the firewall becomes superfluous, as entangled states (or different possible states of a wave function) which reside in spacetimes with sufficiently different geometries will collapse. The ill-definedness of their respective energies due to relativistic effects causes the quantum states to decohere. Could this potentially explain the loss of Hawking radiation pair entanglement?

 

[marcus]

How about some links? An arXiv link for "the Penrose interpretation" would be helpful.
I admit everybody should already have some familiarity with the AMPS paper, but maybe a link to that one too? Some people interested by your post might find it helpful to look back and see what caused the "firewall" uproar back in 2012.

I have the impression that the firewall excitement has quieted down---haven't heard so much about it for the past couple of years. You may have watched it more closely and have a better idea what has been going on.

 

[T S Bailey]

http://arxiv.org/abs/1207.3123 The AMPS paper.
http://citeseerx.ist.psu.edu/viewdoc/download?doi=10.1.1.468.2731&rep=rep1&type=pdf. Penrose's paper
As far as I know no one really takes the firewall seriously as it seems to defy the equivalence principle, but if Penrose is correct then we'd have an entirely different reason to believe in a firewall of sorts without any such violation. The ad hoc nature of the firewall has caused much doubt in the physics community, and I think this is to blame for the relative silence on the subject.

 

[marcus]

Thanks! You might be interested in a recent paper that has a somewhat related idea---quantum gravity effects are invoked and the firewall obviated:
http://arxiv.org/abs/1410.7062
No firewalls in quantum gravity: the role of discreteness of quantum geometry in resolving the information loss paradox
Alejandro Perez
(Submitted on 26 Oct 2014 (v1), last revised 27 Jan 2015 (this version, v2))
In an approach to quantum gravity where space-time arises from coarse graining of fundamentally discrete structures, black hole formation and subsequent evaporation can be described by a unitary evolution without the problems encountered by the standard remnant scenario or the schemes where information is assumed to come out with the radiation while evaporation (firewalls and complementarity). The final state is purified by correlations with the fundamental pre-geometric structures (in the sense of Wheeler) which are available in such approaches, and, like defects in the underlying space-time weave, can carry zero energy.
13 pages, 8 figures. To appear in the special issue "Entanglement and Quantum Gravity" of CQG

 

[marcus]

I see William Unruh has a recent paper that cites the 1996 Penrose paper you pointed out.
http://arxiv.org/abs/1407.7149

==quote Unruh Gooding page 1==
Whereas the decoherence produced by entangling internal degrees of freedom to a center-of-mass coordinate could be considered “third-party” decoherence [10], what we are concerned with here is whether or not there is something about gravity itself that could lead to such intrinsic decoherence. Penrose’s intuition says yes: the path a mass takes alters the associated spacetime and especially the flow of time. Since the quantum phase is determined by the flow of time, the phase evolution is also altered by which path the mass takes. When one tries to interfere the two paths, these “random” phases (because it is impossible to uniquely map one spacetime onto another) cause decoherence. It is this gravitational intrinsic decoherence that we explore here.
==endquote==

Self-gravitating Interferometry and Intrinsic Decoherence
Cisco Gooding, William G. Unruh
(Submitted on 26 Jul 2014 )
To investigate the possibility that intrinsic gravitational decoherence can be theoretically demonstrated within canonical quantum gravity, we develop a model of a self-gravitating interferometer. We search for evidence in the resulting interference pattern that would indicate coherence is fundamentally limited due to general relativistic effects...
...
16 pages, 6 figures. Accepted for publication in Phys. Rev. D

 

[Demystifier]

According to wikipedia
https://en.wikipedia.org/wiki/Black_hole_information_paradox
there are 7 different types of proposed solutions of the information paradox. The firewall is nothing but one sub-type of the type number 2 (Information gradually leaks out during the black-hole evaporation). With so many possibilities, the relevance of the firewall proposal seems largely overemphasized. Other possibilities should be studied too.

Concerning the Penrose proposal, let me only note that it is a sub-type of the type number 1 (Information is irretrievably lost).

 

[marcus]

According to wikipedia
https://en.wikipedia.org/wiki/Black_hole_information_paradox
there are 7 different types of proposed solutions of the information paradox. The firewall is nothing but one sub-type of the type number 2 (Information gradually leaks out during the black-hole evaporation). With so many possibilities, the relevance of the firewall proposal seems largely overemphasized. Other possibilities should be studied too.

Concerning the Penrose proposal, let me only note that it is a sub-type of the type number 1 (Information is irretrievably lost).

I notice your interesting contributions to the BH info paradox discussion, Demy!
Nikolic, Hrvoje (2015). "Violation of unitarity by Hawking radiation does not violate energy-momentum conservation" 04. JCAP: 002. arXiv:1502.04324.
Nikolic, Hrvoje (2015). "Gravitational crystal inside the black hole" 30. Mod Phys. Lett A: 1550201. arXiv:1505.04088.
Nikolic, Hrvoje (2009). "Resolving the black-hole information paradox by treating time on an equal footing with space". Physics Letters B (Phys. Lett.) 678 (2): 218–221. arXiv:0905.0538. Bibcode:2009PhLB..678..218N. doi:https://dx.doi.org/10.1016%2Fj.physletb.2009.06.029 .

I understand your point about the different resolutions to BHIP. This is very important if one's perspective is focussed on that particular problem. Then "firewall" can be seen as just one of many sub-types (maybe not even very interesting or credible compared with other resolutions to BHIP)

But there is another perspective where one is interested in other problems as well which don't involve BH. And the solution to the different problems can overlap. So I'm interested (as a non-expert) in UNRUH talking about intrinsic decoherence. Let me know if this has been debunked and I shouldn't be.
I find it intriguing because it seems like it could resolve SEVERAL puzzles or paradoxes. It could address an intersection of problems, it seems.

TS Bailey's post and Alejandro Perez paper suggest to me how it could resolve BHIP and obviate "firewall" but saying that is more like calling attention to one aspect or application, that is or recently was, somewhat topical. It doesn't define or limit the interest in that idea.

 

[no-ir]

Not really the same as the intrinsic decoherence of Unruh (or perhaps it is?), but the following article might be of interest:

http://www.nature.com/nphys/journal/vaop/ncurrent/full/nphys3366.html
Universal decoherence due to gravitational time dilation
Igor Pikovski, Magdalena Zych, Fabio Costa & Časlav Brukner
Nature Physics (2015) | doi:10.1038/nphys3366
Received 22 January 2014 | Accepted 11 May 2015 | Published online 15 June 2015

The physics of low-energy quantum systems is usually studied without explicit consideration of the background spacetime. Phenomena inherent to quantum theory in curved spacetime, such as Hawking radiation, are typically assumed to be relevant only for extreme physical conditions: at high energies and in strong gravitational fields. Here we consider low-energy quantum mechanics in the presence of gravitational time dilation and show that the latter leads to the decoherence of quantum superpositions. Time dilation induces a universal coupling between the internal degrees of freedom and the centre of mass of a composite particle. The resulting correlations lead to decoherence in the particle position, even without any external environment. We also show that the weak time dilation on Earth is already sufficient to affect micrometre-scale objects. Gravity can therefore account for the emergence of classicality and this effect could in principle be tested in future matter-wave experiments.

---

Might it also be relevant to the BH information paradox, especially Hawking's recent proposal (haven't read his final article yet, though), since it points out that even at low energies gravitational time dilation should lead to "a universal coupling of internal [quantum] degrees of freedom and the centre of mass of a composite particle [a gravitational property of the particle]"?

 

[marcus]

Here's the arXiv link for the Pikovski et al "Universal decoherence..." and also a link to a 2015 follow-up:
http://arxiv.org/abs/1311.1095
Universal decoherence due to gravitational time dilation
Igor Pikovski, Magdalena Zych, Fabio Costa, Caslav Brukner
(Submitted on 5 Nov 2013 (v1), last revised 23 Jun 2015 (this version, v2))
The physics of low-energy quantum systems is usually studied without explicit consideration of the background spacetime... Gravity therefore can account for the emergence of classicality and the effect can in principle be tested in future matter wave experiments.
6+4 pages, 3 figures. Revised manuscript in Nature Physics (2015)
http://inspirehep.net/record/1263356?ln=en (8 cites)

http://arxiv.org/abs/1508.03296
Time Dilation in Quantum Systems and Decoherence: Questions and Answers
Igor Pikovski, Magdalena Zych, Fabio Costa, Caslav Brukner
(Submitted on 13 Aug 2015)
Recent work has shown that relativistic time dilation results in correlations between a particle's internal and external degrees of freedom, leading to decoherence of the latter. In this note, we briefly summarize the results and address the comments and concerns that have been raised towards these findings. In addition to brief replies to the comments, we provide a pedagogical discussion of some of the underlying principles of the work. This note serves to clarify some of the counterintuitive aspects arising when the two theories are jointly considered.
10 pages, 1 figure
http://inspirehep.net/record/1387746?ln=en (3 cites)

Here are links to the related Gooding&Unruh papers, to have them handy.
http://arxiv.org/abs/1407.7149
http://arxiv.org/abs/1503.05488
In the latter, G&U are critical of some aspect of the Pikovski et al paper in Nature Physics.
You might want to check the conclusions section:
==quote Gooding and Unruh==
In the last section, we demonstrated intrinsic decoherence due to time dilation. The decoherence basis is in general a combination of position and momentum, reducing to purely position in the limit of negligible shell momentum. In the system described by Pikovski et al. [2], which includes spacetime curvature caused by the external gravitational field of the earth, the part of the time dilation decoherence that involves the position basis should vanish in the absence of the earth’s gravitational influence: without the earth, the center-of-mass coordinate they use defines the origin of an inertial frame, and in that frame the proper time associated with the center-of-mass coordinate is equal to the coordinate time [9]. However, in our system, this decoherence is present even in the limit of flat spacetime (ignoring both external gravitational fields and self-gravitation), because of the nonzero acceleration of the shell due to the position dependence of the mass (Mˆ = M (X )). We then see a confirmation that the time dilation decoherence proposed in [2] is not necessarily related to gravity, but produced by proper time differences in composite systems with nonzero accelerations.
...
...
It is still an open question whether or not Penrose-type gravitational decoherence can be demonstrated within canonical quantum gravity, without introducing any new physics (for further discussion, see [1]).
...
We have therefore arrived at a type of intrinsic decoherence similar to the “third-party” decoherence described by Stamp [5], though in contrast to the use of the Earth as the third party as proposed by Pikovski et al. [2], we have bootstrapped the idea by incorporating gravitational self-interaction, effectively producing third- party decoherence without the third party.
==endquote==

In http://arxiv.org/abs/1508.03296 , Pikovski et al reply to Gooding and Unruh. See page 6, the first paragraph beginning after equation (7).