Does Kerr's argument against singularities apply to all black holes?

[Suekdccia]

TL;DR Summary

Does Kerr's argument against singularities apply to all types of black hole solutions?

Roy Kerr has recently written a preprint (https://arxiv.org/abs/2312.00841) in which he strongly argues against the possible existence of singularities inside Black Holes.

I've read that his arguments are really powerful and that he is most likely right.

But, does it mean that Kerr has undoubtedly ruled out singularities?

Do his arguments apply to all Black Hole solutions (for example, do they apply for non-rotating Schwarzschild Black Holes)?

What about the Big Bang? Has he ruled out that there was a singularity in those conditions?

Even more, I've read that his arguments mean that, as there are no singularities, there is nothing wrong with quantum mechanics and relativity applied to extreme conditions such as Black Holes' interiors or the Big Bang itself, meaning that all efforts to find new physics, theories of quantum gravity and theories of everything have been in vain. But is this true? Wouldn't that make Kerr's preprint the most important one in theoretical physics for almost half a century? Shouldn't it have hundreds if not thousands of citations by now and published in the most important journals already?

 

[Dale]

TL;DR Summary: Does Kerr's argument against singularities apply to all types of black hole solutions?

But, does it mean that Kerr has undoubtedly ruled out singularities?

No, it means that he has rebutted one argument for singularities. A proof against singularities in general is much more difficult than a rebuttal of a particular argument for singularities.

TL;DR Summary: Does Kerr's argument against singularities apply to all types of black hole solutions?

What about the Big Bang? Has he ruled out that there was a singularity in those conditions?

No. At least not as I understand the argument.

TL;DR Summary: Does Kerr's argument against singularities apply to all types of black hole solutions?

Shouldn't it have hundreds if not thousands of citations by now and published in the most important journals already?

No. Definitely not.

 

[PeterDonis]

Roy Kerr has recently written a preprint (https://arxiv.org/abs/2312.00841) in which he strongly argues against the possible existence of singularities inside Black Holes.

We had two threads on this paper not long ago:

https://www.physicsforums.com/threads/kerr-disputes-singularities-in-kerr-black-holes.1057975/

https://www.physicsforums.com/threads/do-black-holes-have-singularities.1059405/

As you will see if you read those threads, the issue is not as simple as Kerr's paper makes it appear (let alone pop science articles on it). One key point: Kerr is using the wrong definition of "singularities", and while his mathematical proof is valid, what it proves is basically irrelevant to the actual issue of singularities in black hole solutions in GR. It does not mean that, for example, there are no singularities in Kerr spacetime (the solution he discovered) by the standard definition of "singularities" in the literature. In short, Kerr is actually not disagreeing at all with the "consensus" position among relativists that he claims to be arguing against. (See my post #2 in the first thread linked to above for more details.)

I've read that his arguments are really powerful and that he is most likely right.

You've read where?

does it mean that Kerr has undoubtedly ruled out singularities?

Do his arguments apply to all Black Hole solutions (for example, do they apply for non-rotating Schwarzschild Black Holes)?

What about the Big Bang? Has he ruled out that there was a singularity in those conditions?

As you will see if you read those previous threads, the answer to all these questions is "no".

Even more, I've read that his arguments mean that, as there are no singularities, there is nothing wrong with quantum mechanics and relativity applied to extreme conditions such as Black Holes' interiors or the Big Bang itself, meaning that all efforts to find new physics, theories of quantum gravity and theories of everything have been in vain. But is this true?

Not because of any of Kerr's arguments, no.

There are other arguments in the literature for the idea that the things we now call "black holes" are actually objects without any singularities, using the standard definition of that term in the literature (and for that matter, without event horizons); for example, arguments based on models like the Bardeen black hole. But Kerr does not consider those types of models at all, and his arguments have nothing to do with them.

Wouldn't that make Kerr's preprint the most important one in theoretical physics for almost half a century? Shouldn't it have hundreds if not thousands of citations by now and published in the most important journals already?

The fact that the second item here is certainly not the case should raise strong doubts in your mind as to whether the first is the case. (Hint: it isn't.)

 

[Suekdccia]

In short, Kerr is actually not disagreeing at all with the "consensus" position among relativists that he claims to be arguing against. (See my post #2 in the first thread linked to above for more details.)

I think that Kerr is supporting views that are not held by other relativists.

Here he argues that there is nothing singular or strange happening inside black holes, but that they contain a massive spinning neutron star inside (<quora is not a professional scientific source>) which is the first time I've seen that claim as to what happens inside a black hole

And here (<quora is not a professional scientific source>) he says that his colleagues ignore his proof because their careers are built on mistaken foundations (I think that he refers to all physicists working on theoretical ideas of new physics and unified theories of gravity, because if nothing's wrong inside black holes, then there's no need for them)

And also, in the comments of that answer, you can see his argument that inside black holes there are no gravitationally collapsed objects, just ordinary neutron stars, that due to centrifugal forces do not collapse (hence, my question on whether his argument would apply to non rotating Schwarzschild black holes, even if they are unrealistic)

 

[PeterDonis]

I think that Kerr is supporting views that are not held by other relativists.

Some of what he says is, yes. But not his claims about "singularities".

Here he argues that there is nothing singular or strange happening inside black holes, but that they contain a massive spinning neutron star inside

Yes, but he does not claim to have actually found such a solution, just that he thinks one exists. He is mistaken, for reasons I gave in the previous threads I linked to. Briefly, the Penrose diagram of Kerr spacetime shows that there is no way to actually join such an interior solution to Kerr spacetime anywhere inside the event horizon. (As I commented in one of the previous threads, Kerr's disdain for looking at maximal analytic extensions, which is what Penrose diagrams are diagrams of, is misplaced; there is important information there that Kerr ignores.)

he says that his colleagues ignore his proof because their careers are built on mistaken foundations

This is just his unsupported opinion, and since he appears to misunderstand the standard viewpoint, I don't think his opinion carries much weight here.

also, in the comments of that answer, you can see his argument that inside black holes there are no gravitationally collapsed objects, just ordinary neutron stars

Quora wants me to sign in to see the comments, and I don't have an account and don't want to start one. In any case, the arguments that matter are the ones he has put in his papers, not what he says on Quora.

 

[Dale]

Here he argues that …

And here (<quora is not a professional scientific source>) he says

Please review the forum rules on suitable references. We typically allow some latitude in the question of a thread, but not in answers or discussions.

In this case the paper in the OP has not been published in a peer reviewed journal. So even the paper probably would not be acceptable as a response, and certainly his quora posts are not acceptable. In particular, the argument in the second one is the standard crackpot refrain.

 

[PeterDonis]

In this case the paper in the OP has not been published in a peer reviewed journal.

Since we have already had previous threads on the paper, I don't think we can disqualify it. (The fact that it's by Roy Kerr makes it, IMO, at least interesting enough to warrant some kind of PF thread.) But of course that reasoning doesn't apply to Quora posts.

 

[Dale]

Since we have already had previous threads on the paper, I don't think we can disqualify it.

I agree, as an OP, like is done here. We are more relaxed for questions and thread starts than for answers and arguments.

 

[Suekdccia]

Please review the forum rules on suitable references. We typically allow some latitude in the question of a thread, but not in answers or discussions.

In this case the paper in the OP has not been published in a peer reviewed journal. So even the paper probably would not be acceptable as a response, and certainly his quora posts are not acceptable. In particular, the argument in the second one is the standard crackpot refrain.

I understand that quora is not a scientific source, but I was indicating sources coming directly from Mr. Kerr

 

[Dale]

I understand that quora is not a scientific source, but I was indicating sources coming directly from Mr. Kerr

So what? What does that have to do with the acceptability?

 

[Suekdccia]

So what? What does that have to do with the acceptability?

I think it might be insightful to consider other sources outside of strict published papers when the author himself is the one posting them... but it's just my opinion, I'm not a moderator

 

[Dale]

I think it might be insightful to consider other sources outside of strict published papers when the author himself is the one posting them.

Well-respected authors often say many things that would not pass peer review when they are writing in non peer reviewed venues. Therefore such sources are not acceptable except insofar as they are consistent with the professional scientific literature.

In particular, the argument that Kerr makes in the second post is anti-insightful. Far from actually supporting his argument, it makes him look like a crackpot himself by his espousing this staple crackpot complaint. It severely undermines his credibility, and it sheds no light on the technical argument.

 

[PeterDonis]

I think it might be insightful to consider other sources outside of strict published papers when the author himself is the one posting them

Not from the standpoint of PF, it isn't, for the same reason that we don't accept pop science books as sources even when they are written by scientists who have published papers or even won Nobel Prizes. What scientists are able to claim in textbooks and peer-reviewed papers is limited, because there are other scientists in the loop who can push back against errors or unjustified claims. What scientists claim in other venues are not constrained by those considerations, and that makes what they say in those venues unreliable as a source for learning actual science, however informative it may be about the personal opinions of that particular scientist.