Does Hawking deserve a Nobel prize for his singularity theorem?

Phrak

I'd like to see someone defend his assertion against the strong doubts as I've expressed in my signature below. Maybe I'm just too stupid to get it, but without it, I'll continue to think the black hole believers are happily delusional.

JesseM

Do you think it's delusional to think general relativity is probably correct at far lower energy densities than the Planck scale, and thus that its theoretical predictions about collapsing stars becoming black holes are very likely to be correct too? Or do you think that, even given the assumption that GR is correct on a theoretical level, it's delusional to think that various astronomical objects which appear to fit the profile for what GR would predict about black holes (like this one, which does have what seems to be an accretion disc and jets in photos...likewise, see here and here for photos of a jet from the center of M87 which is believed to contain a supermassive black hole) are in fact black holes?

Altabeh

Actually I feel you are a little bit too delusional about things that are not today talked about from the angle you see 'em because it's been a long time since they were discovered in the real world. You get to have a look at this article which provides an observational evidence for the accretion disk origin for a radio jet or just visit Arxiv.org and start searching the relevant stuff in there to find over than 1,000 entries on the subject of accretion disks, removing your doubt in their existence!

AB

Frame Dragger

I'm going to go out on a limb here and assume that Phrak is aware of current imaging studies of (commonly accepted, by me as well) BHs. I think he's positing that something other than a singularity enshrouded by an event horizon is causing polar jets, and accretion discs. At this point however I'd say that's a pointless speculation. BHs are not wild theory, but the best working material a pretty well verified theory (GR) provides us with. Does that mean that the superdense object behaving like a BH is actually a point where... well... everything is destroyed utterly at the singularity? Who knows, and new theories to describe such a space aren't being developed by people who reject their existence entirely.

Personally, I don't think it matters right now, because the models of whatever is generating the artifacts observed in the images linked by JesseM and Altabeh must be VERY close to an object that would be hidden by an Event Horizon. Does it really matter if it's a String Theory "Fuzzball" behind that event horizon, or "Green Slime and Lost Socks"? No. Unless earthbound anaogues of BHs can show experimental evidence of HR, we'll just have to wait in even more precise mesurements. That said, from a purely phenomenological it doesn't matter one way or the other.

Singularities are predicted by GR, and the associated artifacts have PROBABLY been observed, and provide explanations of LGRBs, superluminal jets, etc... Before you stand on the mountaintop and shout that everyone is a fool for believing in, or working with, the best current observations backing up a well verified theory... offer YOUR brilliant explanation... and please, in the kind of detail you'd expect from someone with a view contrary to your own.

Finally... if you want to make a point in a serious discussion online, your signiture is not the best delivery mechanism. ;)

stevebd1

While I have no issue with current black hole theory, I do think the alternative black star sounds interesting.

Related paper-

'Small, dark, and heavy: But is it a black hole?' by Matt Visser, Carlos Barcelo, Stefano Liberati & Sebastiano Sonego (2009)

http://arxiv.org/abs/0902.0346

Frame Dragger

It is interesting, but as with formulations for naked singularities, gravstars, etc... it doesn't work in all of the multitutde of situations where (gravitational) singularities arise in GR. Before we go off inventing theories that are essentially baseless because we dislike the IDEA of a BH, maybe closer examination of these massive bodies is warrented?

atyy

Visser's work is motivated by quantum gravity considerations. At present, there is no known way to extend the Einstein-Hilbert to the Planck scale. So the possibility that the EH action is only a low energy effective action is being explored. However, the Weinberg-Witten says that the EH action cannot be a low energy effective action if the high energy action is Lorentz invariant, 4 dimensional etc. Thus high energy actions without Lorentz invariance are being theoretically explored by Visser and Horava, among others. If Lorentz invariance is broken, there is an argument from Ted Jacobson that black holes can be perpetual motion machines, which suggests either that Lorentz invariance is not broken or that black holes do not exist.

Frame Dragger

I think that the simple fact that there is no unification between the macroscopic and microscopic makes me leery of challenges to the existance of BHs such as those from Ted Jacobson. There are plenty of theories which are consistant with observations and GR/SQM, but they are unproven and maybe unrproveable. Alas. Then again, maybe BHs really are enshrouded singularities, or boundary conditions on which information is encoded a la The Holographic Principle. Nothing I've read from Visser or others is convincing in all of the many ways that collapse or accretion could lead to some BHs. In some cases they make more sense... but when has that ever mattered?

atyy

What is SQM?

Frame Dragger

Standard Quantum Mechanics.

EDIT: good point... could be Scaled, or Supersymmetric. Lets just say GR/QM

Altabeh

But this is in a total disagreement with the mechanism of Kerr black holes, because they lose mass by the emission of massive particles and HR and therefore angular momentum and this means they will stop rotating someday. Though it is not proved practically that the primordial rotating black holes would become motionless today nor is it that HR exists in the real world, I can't completely disagree with the Jacobson's idea! What if the HR is just a theory?

AB

atyy

As I understand, Jacobson's idea (http://arxiv.org/abs/0804.2720) isn't relevant in standard GR or QFT on curved spacetime since those are have local Lorentz invariance.

People have suggested that there should be analogues of black holes in condensed matter systems, and that we should be able to detect Hawking radiation from them. But many of these suggestions don't have Lorentz invariance, so does that mean that we can have perpetual motion machines or that we can't have black hole analogues? These guys say we can't have perpetual motion machines, we can't have event horizons, but we can get Hawking radiation (http://arxiv.org/abs/gr-qc/0607008).

Frame Dragger

This is why, when I start talking about this kind of thing with friends who are NOT interested in theoretical physics, they walk away with their eyes rolling.

I don't know... and I don't know that anyone does for sure. GR and QM alone can only describe a BH to a certain extent... mostly up to the EH. To be honest however, even the exact flows in the accretion disk have only been partially modeled. I wouldn't assume that BHs are PMMs, violate Unitarity, or crush matter out of existence at a singularity before the math advances, or an analgoue DOES produce confirmatory evidene of an existing theory.

After all, what happens beyond the EH, stays beyond the EH for any external observer, unless it's encoded on the EH... *head hurts*.

If a BH loses mass through periods of NOT accreting, and emitting HR, to the point of eventual destruction (whatever form that takes) I fail to see how they can be perpetual motion machines, even in theory. They require angular momentum from their original collapsing body, or from infalling matter to rotate, and without infalling matter they slowly shrink and "get hotter". Seems like a strange thermodynamic process (or analogue thereof), but it seems limited.

sezw

i think if they gave obama a peace prize for continuing a war they should definately give hawkins a nobel physics award

mgb_phys

Sorry - is that supposed to make sense?
If they gave Halle Berry the oscar for the worst Bond movie in history - they should give Terry Pratchett the Booker prize for Good Omens.

Frame Dragger

1.) HAHAHAHAHHAAHA

2.) I think perhaps he doesn't grasp the division between one prize awarded by politicians, and the other which is awarded by academicians.

3.) That is a warped sense of parity indeed.

JesseM

But is he positing that this would be possible in GR, or is he positing that GR is incorrect even in the classical limit? I think they've shown that, based on the mass of the objects inferred from orbiting stars and the maximum possible radius inferred from the radius at which the stars closest to them are orbiting, that they are definitely over the Schwarzschild limit, so according to GR there doesn't seem to be any way to escape the conclusion that they're black holes and not just really dense quark stars or whatever...