tag:blogger.com,1999:blog-8666091.post8809003589261320683..comments2021-10-04T19:28:06.851+02:00Comments on The Reference Frame: Bousso's pseudoarguments against \(ER=EPR\), black hole complementarityLuboš Motlhttp://www.blogger.com/profile/17487263983247488359noreply@blogger.comBlogger21125tag:blogger.com,1999:blog-8666091.post-45275669103945659812013-08-20T11:39:18.395+02:002013-08-20T11:39:18.395+02:00Dear Anonreader,
I am used to Matrix theory'...Dear Anonreader,<br /><br /><br />I am used to Matrix theory's being forgotten. As long as that there are at least some people who don't forget all of science, the situation isn't hopeless.<br /><br /><br />It is not clear to me what you mean by "in the first place" when you talk about the existence of the horizons. What does it mean? If it means that they're there in an approximation, the answer is Yes. If it means that they were there first historically when gravity started to be studied as the curved spacetime, it's Yes. There may be other "in the first place" approaches - starting from other starting points in the first place - that don't have the horizon in the "first place". It's not an exact notion if the black hole is evaporating.<br /><br /><br />Yes, the equivalence principle also presupposes that the space near the large black hole horizon has all the properties expected from an empty flat space because the space is supposed to be nearly flat according to classical GR (plus small corrections). If the fluctuations near the horizons become larger or qualitatively different from those you could say in empty space, I would say that the equivalence principle is violated, too - simply because they would allow you to detect whether there is a horizon gravitational field, or whether it's due to acceleration, and that's what the equivalence principle is supposed not to allow you to distinguish.Luboš Motlhttp://motls.blogspot.com/noreply@blogger.comtag:blogger.com,1999:blog-8666091.post-48453931135141635342013-08-20T07:18:46.876+02:002013-08-20T07:18:46.876+02:00Thanks again -- this is very helpful. And sorry ab...Thanks again -- this is very helpful. And sorry about forgetting about Matrix theory!<br /><br /><br /><br />I guess my question boils down to how circular some of these arguments are. If we assume that there's a horizon, then obviously any exp(-S) effects that allow information to go back through the horizon to the outside world must be nonlocal. But if the horizon isn't exactly a horizon in the first place, then why must leaking information be nonlocal?<br /><br /><br />As for the equivalence principle, that presupposes some given gravitational field, and says that the gravitational field should look like nothing to a free-falling observer. But if the gravitational field is corrected by fluctuating exp(-S) effects, then the necessary free-fall frame keeps changing, and so a smoothly traveling observer won't be able to stay in exactly the right free fall frame all the time, and should see fluctuations. But that's not really a violation of the equivalence principle, right, because the field itself keeps fluctuating. Or is this incorrect?<br /><br /><br />Thanks so much for humoring my confusions!Anonreadernoreply@blogger.comtag:blogger.com,1999:blog-8666091.post-55202603012357912452013-08-20T07:12:14.695+02:002013-08-20T07:12:14.695+02:00Umm, I'm not so sure that it is hopeless as wh...Umm, I'm not so sure that it is hopeless as where should be a way to compute the relative entropy of the two regions. That is my question for now. Thanks.Stephen Paul Kingnoreply@blogger.comtag:blogger.com,1999:blog-8666091.post-4904013256183598642013-08-20T07:09:50.438+02:002013-08-20T07:09:50.438+02:00Dear Anonreader,
the classical equations and the...Dear Anonreader,<br /><br /><br />the classical equations and their solutions are surely not precise descriptions of reality up to the precision exp(-S). They're just the leading approximation and already the first power-law corrections, of which R^2 squared-curvature terms are an example, represent quantum corrections that surely do appear in the reality.<br /><br /><br />What is precisely said about the exponentially tiny corrections is that corrections of size comparable to exp(-S) etc. are those that violate not only the precise form of the classical equations but even the *principles* of the classical theory - locality - that are apparently preserved by all conceivable higher-order corrections.<br /><br /><br />Yes, this (exponentially tinily) leaking horizon is exactly what may be credited for the preservation of the information. The Hawking radiation arises from the tunneling of a sort. So when one talks about the microscopic details, every piece of information can leak. But when one observes low-energy phenomena, the horizon should behave classically.<br /><br /><br />It is not true that AdS/CFT is the only precise UV complete description of QG we have. At least Matrix theory is another example.<br /><br /><br />All black holes preserve information - as far as these qualitative properties go, the properties of all black holes in all quantum theories of gravity is the same.<br /><br /><br />Best wishes<br />LMLuboš Motlhttp://motls.blogspot.com/noreply@blogger.comtag:blogger.com,1999:blog-8666091.post-30381124545921931202013-08-20T07:04:18.577+02:002013-08-20T07:04:18.577+02:00It tells us something but the information is proba...It tells us something but the information is probably hopelessly scrambled.<br /><br /><br />Yes, it's monogamous because those measurements on the Hawking radiation far away and some of the properties of the black hole interior are the *same* degrees of freedom - geometrically, they are functional of field modes on two regions of spacetime that are actually very close to each other if one walks over the bridge.Luboš Motlhttp://motls.blogspot.com/noreply@blogger.comtag:blogger.com,1999:blog-8666091.post-36810992815670629582013-08-20T06:51:35.615+02:002013-08-20T06:51:35.615+02:00Thanks for the clear response!
I am perfectly co...Thanks for the clear response!<br /><br /><br />I am perfectly comfortable believing in classical GR all the way down to exp(-S) corrections, which are obviously extremely tiny for all but the tiniest black holes.<br /><br /><br />But how can we trust that the classical solution for the gravitational field is correct all the way down to that level of exp(-S) precision? And if the event horizon is "broken" at the level of such tiny corrections, then won't it leak just enough information to ensure the outgoing radiation is unitary?<br /><br /><br />I know that event horizons are global concepts, but the real question is whether there are gravitational fields that are strong enough and consistent enough all the way down to those tiny corrections that they can keep ahold of every bit of information and prevent it from escaping, and how do we know we can trust quantum gravitational fields to do that?<br /><br />The only precise UV complete theory of quantum gravity we have is from AdS/CFT, and the CFT duals to black holes leak information, and are consistent with unitarity. So isn't that evidence that the quantum black holes in the bulk are slightly leaky too?<br /><br /><br />Thanks again!Anonreadernoreply@blogger.comtag:blogger.com,1999:blog-8666091.post-30176946355968458472013-08-20T06:51:18.153+02:002013-08-20T06:51:18.153+02:00Would this tell us things about the "back act...Would this tell us things about the "back action" of measuring the Hawking radiation? It seems that it should due to monogamy. Just wondering.Stephen Paul Kingnoreply@blogger.comtag:blogger.com,1999:blog-8666091.post-81559017529010932032013-08-20T06:42:46.225+02:002013-08-20T06:42:46.225+02:00Hi, well, this is a good question, the same fundam...Hi, well, this is a good question, the same fundamental question that underlies this very controversy.<br /><br /><br />My view is that we know that the event horizons are formed even with QG effects included because they are a classical GR phenomenon and they are unambiguously implied by the evolution in GR whose terms in the equations have been validated experimentally. Only when some well-defined observables reach extreme values not compatible with the classical GR approximation, the quantum effects may kick in.<br /><br /><br />One may perhaps argue that the black hole interior - and even vicinity of the horizon - is already transgressing to the quantum regime although such a view is a violation of the equivalence principle which allows us to use a flat-space-like description for regions that are nearly flat even though they are "naturally" described by singular coordinate systems as well.<br /><br /><br />But if someone claims that there are new effects near the would-be horizon of a young black hole, and Bousso does, it is an extra problem: the location of the event horizon isn't even determined before all the evolution ends. A point on the surface of a neutron star may suddenly turn out to be in the black hole interior although it looks very similar to the point just a nanosecond earlier which was outside. So claiming that some quantum effects appear in between them violates not only the equivalence principle but also causality - such a distinction would have to know the future history in advance.<br /><br /><br />One could perhaps change the moment when the quantum effects become substantial to another surface near the event horizon such as the apparent horizon etc. Nature may be hiding surprises but I personally don't think that She will force us to abandon the equivalence principle near the event horizon completely because the interior and exterior start as connected through ordinary nearly flat space and there's no reason why the nature of the connection should qualitatively change over time - and I even think that the normal continuation of the space past a surface (horizon) is the only consistent way to continue physics. There are all kinds of microscopic correlations but those are exponentially tiny so that they become invisible to a low-energy observer.Luboš Motlhttp://motls.blogspot.com/noreply@blogger.comtag:blogger.com,1999:blog-8666091.post-19176860672601071192013-08-20T06:33:12.805+02:002013-08-20T06:33:12.805+02:00Alice - I suppose you mean an infalling observer -...Alice - I suppose you mean an infalling observer - doesn't have the access to all the microscopic degrees of freedom. Her limited time until the rest of her life clearly prevents her from measuring every detailed microscopic property of the black hole.<br /><br /><br />That doesn't mean that those degrees of freedom can't affect her and the rest of her life. Of course that they can. The ER bridge picture makes the reason manifest. The black hole interior is connected with wormholes to distant places of the Hawking radiation so the operations done with the Hawking radiations do influence the black hole interior seen by Alice.Luboš Motlhttp://motls.blogspot.com/noreply@blogger.comtag:blogger.com,1999:blog-8666091.post-39800164477087818612013-08-20T04:34:26.290+02:002013-08-20T04:34:26.290+02:00Apologies in advance for my naive question, Lubos....Apologies in advance for my naive question, Lubos.<br /><br />Given that we don't yet have a sufficiently completely understood theory of quantum gravity yet and are relying on semiclassical gravity in a lot of these black hole discussions, how do we know for sure that black holes truly develop exact event horizons in the first place? At the classical level, sure, black holes have nice event horizons, but how do we know once we start taking quantum-gravity effects into account that event horizons on black holes (as opposed to, say de Sitter horizons) are really, exactly information-trapping and don't leak information, beyond Hawking's original prediction of thermal radiation? And if black holes, as quantum objects, don't have exact event horizons, then don't a lot of these puzzles go away?<br /><br />I'm hoping you can tell me (or point me to a paper with) the most trustworthy argument in favor of the view that event horizons can be trusted to be exact even once we open the door to (not fully understood) quantum-gravity effects.<br /><br />Thanks!Anonreadernoreply@blogger.comtag:blogger.com,1999:blog-8666091.post-39936718983455223562013-08-20T03:13:37.172+02:002013-08-20T03:13:37.172+02:00Please explain this: "Of course that there ca...Please explain this: "Of course that there can't be any contradiction if we're forced to look <br />at the out state whenever we want to restrict our attention to <br />microstates that see the vacuum near the horizon." How are these microstates measurable by Alice?Stephen Paul Kingnoreply@blogger.comtag:blogger.com,1999:blog-8666091.post-55686671820658709922013-08-20T02:01:13.673+02:002013-08-20T02:01:13.673+02:00There is a certain madness to the amount of ads in...There is a certain madness to the amount of ads in your posts. Just saying.Sandranoreply@blogger.comtag:blogger.com,1999:blog-8666091.post-47210824480339478132013-08-19T22:28:34.703+02:002013-08-19T22:28:34.703+02:00Are you referring to anything in Bousso's pape...Are you referring to anything in Bousso's paper? I can't see any mention of anything topological. However, I think Kauffman has done some work the relationship between knots, braids, quantum entanglement and quantum computing.lucretiusnoreply@blogger.comtag:blogger.com,1999:blog-8666091.post-8516321777351571282013-08-19T22:25:49.518+02:002013-08-19T22:25:49.518+02:00I can't understand why this whole culture of &...I can't understand why this whole culture of "the equivalence principle <br />has to be totally wrong" has spread in the quantum gravity literature. <br />It's so self-evidently wrong and it's been discussed for decades. For <br />two decades, we have known why similar would-be arguments that lead to <br />paradoxes don't really work. Every expert was saying these things. Why <br />didn't they protest 15 or 20 years ago?<br /><br /><a href="http://hcgrecipesphase2z.com/hcg-diet-recipes-phase-2/" rel="nofollow">best hcg diet recipes phase 2</a> <br>Brooke Ansteyhttp://hcgrecipesphase2z.com/noreply@blogger.comtag:blogger.com,1999:blog-8666091.post-19639784665239840392013-08-19T21:29:36.642+02:002013-08-19T21:29:36.642+02:00Yep, they should send it for peer review to Lumo, ...Yep, they should send it for peer review to Lumo, and Lumo posts the review here on TRF :-)<br /><br /><br />Indeed, this article reads like a peer review that says "reject" at the end ;-)Dilatonnoreply@blogger.comtag:blogger.com,1999:blog-8666091.post-7868940772983745002013-08-19T21:18:22.774+02:002013-08-19T21:18:22.774+02:00I was trying to see if I can give a sort of "...I was trying to see if I can give a sort of "topological interpretation" to quantum mechanics... now that everyone is interested in "interpretations"... apparently others did it first but the field is not exhaustedandnoreply@blogger.comtag:blogger.com,1999:blog-8666091.post-5213457699599554922013-08-19T21:12:34.194+02:002013-08-19T21:12:34.194+02:00Are there any more comments or explanations about ...Are there any more comments or explanations about how entanglement is a topological charge?andnoreply@blogger.comtag:blogger.com,1999:blog-8666091.post-54072217960601646942013-08-19T17:32:46.656+02:002013-08-19T17:32:46.656+02:00agreed and liked! agreed and liked! andnoreply@blogger.comtag:blogger.com,1999:blog-8666091.post-28486796198796611792013-08-19T15:36:57.241+02:002013-08-19T15:36:57.241+02:00Dear lucretius, believe me that rather than the ex...Dear lucretius, believe me that rather than the excess material for criticism, I would be excited about further advances that would be e.g. comparable to ER-EPR every other day. ;-)Luboš Motlhttp://motls.blogspot.com/noreply@blogger.comtag:blogger.com,1999:blog-8666091.post-48072058665808361222013-08-19T15:28:18.356+02:002013-08-19T15:28:18.356+02:00But if they stop posting it, we will loose your in...But if they stop posting it, we will loose your instuctive and entertaining commentary/criticism. Maybe they should just send it straight to you? ;-)lucretiusnoreply@blogger.comtag:blogger.com,1999:blog-8666091.post-23368485447064458372013-08-19T13:17:14.386+02:002013-08-19T13:17:14.386+02:00A lot of papers are overly complex, it's as if...A lot of papers are overly complex, it's as if the author is <br />deliberately out to distract and confuse, while promoting how <br />intelligent they are due to the complexity of their work.Sparksnoreply@blogger.com