A Critique of the Fuzzball Programby Suvrat Raju as well as his graduate educatee Pushkal Shrivastava. They criticize the whole prototype of the fuzzballs – an approach to sympathise dark hole thermodynamics – which is mostly associated alongside the cry of Samir Mathur, run across his 2007 invitee blog as well as dozens of other posts.
I know Suvrat from Harvard, he's been an amazing T.A. inwards a course of written report of mine, as well as I soundless honey his numerous papers such every bit the papers almost the dark hole interior written along alongside Kyriakos Papadodimas. There is e'er around score of perfectionism inwards his piece of work as well as reliance on explicit equations.
(Lots of people inwards politicized scientific discipline disciplines should appreciate what variety of a laid clean praise the radical Marxist Suvrat Raju may wear a right-wing blog. Is that possible inwards your field? What almost the climate science? I added this paragraph after – because I simply couldn't resist.)
Mathur's fuzzballs are proposed models for dark hole microstates – effectively around precise star-like solutions of the supergravity plain equations (or, to a greater extent than speculatively, solutions that involve non-local degrees of liberty inwards string/M-theory).
In the SUGRA case, these star-like equations have got been explicitly written downward for around highly supersymmetric dark holes whose horizon expanse is solely nonzero because of the nonzero quantum corrections. In these solutions, the dark hole interior is replaced alongside lots of fuzz – around pilus – which may survive constructed from ALE-like spaces for every shape of a string (which contributes to the moving ridge functional of a string model of a dark hole). Black holes alongside a decreasing amount of supersymmetry or alongside the increasing role of the classically nonzero horizon areas are realized every bit increasingly speculative as well as non-explicit fuzzballs that are increasingly probable to involve around non-local degrees of liberty which are less understood.
What you lot may let out cool is that both sides of this fuzzball debate are Indian – Republic of Republic of India is truly total of sultans of string. Communist People's Republic of China is expanding inwards many industries but I mean value it's completely accurate to tell that the Indians are to a greater extent than of import players than the Chinese inwards formal theoretical high-energy physics. At whatever rate, the fuzzball is an of import plenty sentiment as well as so that quantum gravity experts should have got around enquiry or statements almost it inwards the whole world. It may hold back surprising that Republic of Republic of India is soundless leading – as well as it's leading both sides. Republic of Republic of India has harbored around amazing civilizations thousands of years agone – but I soundless mean value that when it comes to mathematics as well as the modern theoretical physics, the Indians should survive grateful to the British majestic overlords for having arranged the environs as well as providing role models. Even Jamsetji Tata (the tata of the Tata industrial family) had to written report at the Elphinstone College first.
OK, Suvrat as well as Pushkal debate that just when the fuzzballs are said to survive relevant for the dark hole microstates, dark hole interior etc., the quantum corrections larn large as well as so the fuzzballs can't survive trusted. For this reason, these fuzzballs shouldn't survive able to tell anything almost the dark hole interior (and hence almost the dark hole data puzzle).
I tend to concur alongside these statements. It seems to me that fifty-fifty Mathur would have got to agree. He has talked almost the "fuzzball complementarity" which should imply, if I correctly assume that he preserves around mutual sense, that the fuzzball geometry – which is nontrivial as well as hairy (violating the lore or "invalid theorems" almost the absence of the dark hole pilus inwards the relevant contexts) – should have got aught to produce alongside "what the infalling observer sees inwards the dark hole interior".
So I mean value that the "black hole complementarity" promoted past times Mathur must include the contestation that the fuzzball as well as the sense of an infalling observer inwards the dark hole interior have got real footling to produce alongside 1 around other – they're around dual descriptions of similar degrees of freedom. So the fuzzballs are simply around unusual, dual means to parameterize the microstates.
But Suvrat as well as his educatee transcend further. They claim that because the interior is described "incorrectly" past times the fuzzballs, it follows that these fuzzball solutions solely depict around multiplicity of the possible geometries "slightly outside" the lawsuit horizon. For that reason, the entropy coming from the fuzzballs shouldn't survive identified alongside the dark hole entropy – the entropy of the interior. Instead, they should survive added.
I have got around problem alongside this contestation because inwards Mathur's most famous example, that would appear to imply that the total entropy is twice every bit large every bit it should be.
It seems to me that simply because around quantum corrections are large doesn't imply that the uncorrected degrees of liberty obeying the uncorrected equations can't depict the right degrees of freedom. Some of the equality of the ii entropies could survive guaranteed past times the supersymmetric nonrenormalization theorems. If something agrees, 1 should soundless know whether around understanding solely holds when it's protected past times supersymmetry; or whether it holds to a greater extent than by as well as large fifty-fifty inwards the absence of sufficient supersymmetry.
In the Strominger-Vafa dark hole, you lot may mean value of the organisation every bit around curved dark holes or D-branes alongside lots of excited opened upwardly strings stretched betwixt them. The latter motion painting includes no quantum corrections. But the ii entropies are soundless the same as well as should survive identified. You may extrapolate the flat-space states alongside D-branes as well as opened upwardly strings to a potent coupling. It's an instance of the open-closed and/or holographic duality – but honestly, inwards this case, the extrapolation of the entropy is solely possible due to the supersymmetric nonrenormalization theorems. Does the newspaper past times Raju as well as Shrivastava comprise a proof that the fuzzball solutions can't survive around other dual description of the same Hilbert infinite of microstates? Maybe it does. My existent occupation is that I truly believe that the fuzzballs are right inwards this sense.
But for the dark hole interior phenomena, I produce concur that the fuzzballs are wrong or irrelevant. Mathur would envision around variety of "averaging over the fuzzballs" that is needed to reconstruct the observations made past times an infalling observer. Does he truly have got a quantitative dominion how this "averaging" is supposed to survive made? What are the observables that 1 is averaging? Are in that location any? I dubiety it. There are no background-independent local plain observables inwards quantum gravity, nosotros believe – but those are just the observables you lot would require to "exist" that should survive averaged. So there's truly aught well-defined to accept the average over fuzzball solutions from.
So again, I mean value that in that location are ii unlike questions – whether fuzzballs as well as their generalizations may survive used to parameterize the dark hole microstates; as well as whether they tin reply questions almost the (infalling observers') observations inwards the dark hole interiors. I mean value that the answers are Yes as well as No, respectively.
Update: Suvrat wrote a fun postal service to me. He agrees that in that location are ii questions as well as they mostly discussed the inapplicability of the fuzzball solutions for questions almost the dark hole interior. Suvrat adds that the claim almost "addition of ii entropies" was simply a quote taken from Ashoke Sen – an Indian, of course.
Most amusingly, I was informed that the comment almost Marxism is relevant because their championship is a parody of The Critique of the Gotha Program, around Marxist rant. (I couldn't have got guessed it fifty-fifty if I had 1 one yard 1000 attempts as well as if I were protected from the Marxist materials past times 5,000 condoms.) There's a problem, however: the Marxist rant is "the" critique spell theirs is "a" critique! ;-)