I What problems would 'black holes' not being formed solve?

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there is nothing to stop the formation of the event horizon. Time dilation is not a local phenomena, so locally a particle falling toward the event horizon just passes through it without even noticing.
This seems to be quite popular argument but it is obviously faulty as it assumes conclusion.
This is not a case of assuming the conclusion, it is a rebuttal of a specific argument. The argument is that there would be infinite time dilation near a horizon. The rebuttal that time dilation is not a local phenomenon is valid.

The argument assumes the horizon and tries to show proof by argumentum ad absurdum that the horizon does not exist. The rebuttal is perfectly entitled to assume the horizon (required in fact) in demonstrating the non-absurdity of the result.
 

zonde

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it is a rebuttal of a specific argument. The argument is that there would be infinite time dilation near a horizon.
No, that was not the argument. The post to which russ_watters replied was talking about the very center of collapsing body and formation of singularity along with event horizon there.
and if you take a collapsing star, the singularity would form at the centre, right? And the event horizon would expand from there as the star fell into it..

But why would a singularity form at all? As time dilation rose, then the matter compressing in the area would rise, slowing compression. I don't see how time dilation could ever reach infinity at any point, like I said, as matter at the centre compressed, the process would slow down, and prevent infinite time dilation occurring and hence a singularity..
 
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No, that was not the argument. The post to which russ_watters replied was talking about the very center of collapsing body and formation of singularity along with event horizon there.
Hmm, I don’t see where you are coming from. The formation of the event horizon is clearly assumed since that is where time dilation becomes infinite.

It is an argumentum ad absurdum. The whole point of argumentum ad absurdum is to assume the thing you wish to disprove. Formation of an event horizon predicts infinite time dilation, infinite time dilation is absurd, therefore the event horizon cannot form. And the rebuttal is that infinite time dilation is not absurd after all.

Edit: perhaps you and I are understanding @DarkStar42’s argument differently, and hence the rebuttal also. In any case the rebuttal is not “obviously” faulty, since with at least one reasonable understanding of the argument it is not faulty at all.
 
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russ_watters

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In first sentence you talk about formation of event horizon, but in second sentence you talk about particle falling towards already formed event horizon.
Ok, going back and reminding myself of the OP and the issue a bit, I see that I changed the scenario slightly from an event horizon never forming to an object falling into an already formed event horizon. I wrote this a while ago, but I believe the reason is that the OP's event horizon never forming scenario is a logically flawed scenario because it describes something that doesn't exist preventing its own formation. Mine avoids the issue of arguing that something that doesn't exist can prevent its own formation. The logic is the same for both (there is actually nothing there to prevent collapse), but mine avoids that contradiction.

[edit2] Note, reducto ad absurdum is a legitimate logical tool, not a fallacy. The OP used the logical tool correctly, but was simply missing a piece of key information about reality that then led to the wrong conclusion. But there's nothing wrong with the approach. It's really just falsification.

[edit3]
And not for nothing, but pretty much nobody ever talks about logical fallicies in scientific contexts. The logic of science is precise; it's derived from [it is] math. This isn't politics, where there are no right answers and arguments can be won on strong rhetoric alone.
 
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zonde

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I wrote this a while ago, but I believe the reason is that the OP's event horizon never forming scenario is a logically flawed scenario because it describes something that doesn't exist preventing its own formation.
You are a bit cryptic so I have to guess that "something" is infinite time dilation. In that case it's not quite the case. OP expressed his doubts that ever increasing finite time dilation prevents configuration from reaching infinite time dilation. So I see no flaw you are talking about.

Note, reducto ad absurdum is a legitimate logical tool, not a fallacy.
Yes, reducto ad absurdum is a legitimate logical tool.
Ok, now I see what you are getting at.
We assume the opposite - that ever increasing finite time dilation does not allow reaching infinite time dilation. In that case particle falling into BH will never cross event horizon which is absurd, right? But your example requires us to believe that BH model is the only possible explanation for super massive astronomical objects we call "Back Holes". Well, it still seems circular reasoning to me.

And not for nothing, but pretty much nobody ever talks about logical fallicies in scientific contexts. The logic of science is precise; it's derived from [it is] math. This isn't politics, where there are no right answers and arguments can be won on strong rhetoric alone.
I'm not sure what do you mean by "logic of science". In any case in science there are no right answers (there are answers that work within some domain of applicability), but certainly there are plenty of answers that are wrong (they contradict observations), inconsistent, ambiguous, untestable. And in science you try to get rid of all these answers.
 

zonde

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It is an argumentum ad absurdum. The whole point of argumentum ad absurdum is to assume the thing you wish to disprove. Formation of an event horizon predicts infinite time dilation, infinite time dilation is absurd, therefore the event horizon cannot form. And the rebuttal is that infinite time dilation is not absurd after all.
OP does not say or suggest that he considers infinite time dilation as absurd. He said that ever increasing finite time dilation will prevent infinite time dilation occurring.

Edit: perhaps you and I are understanding @DarkStar42’s argument differently, and hence the rebuttal also. In any case the rebuttal is not “obviously” faulty, since with at least one reasonable understanding of the argument it is not faulty at all.
You can not justify faulty argument by constructing a "straw man".
 

russ_watters

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You are a bit cryptic so I have to guess that "something" is infinite time dilation.
There is nothing cryptic here: this discussion is about the existence or non-existence of the event horizon. The OP assumes its existence in his argument that it can't exist. And there is no logical fallacy in doing so.
Ok, now I see what you are getting at.
We assume the opposite - that ever increasing finite time dilation does not allow reaching infinite time dilation. In that case particle falling into BH will never cross event horizon which is absurd, right?
No. You had it right up to the conclusion. The OP's argument is self-contained and consistent for what it is. In essence, he's describing a divide-by-zero error you get by plugging a "0" into the equation for time dilation at a given distance from the event horizon (vs infinite distance, I believe). Divide by zero is an error, so the event horizon can't form. That's his argument.
But your example requires us to believe that BH model is the only possible explanation for super massive astronomical objects we call "Back Holes". Well, it still seems circular reasoning to me.
No. My argument is a specific rebuttal to the specific claim that a certain math says black holes can't exist/form. It does not go beyond that. There certainly may exist other models that can explain our observations, that haven't been found yet.
I'm not sure what do you mean by "logic of science". In any case in science there are no right answers (there are answers that work within some domain of applicability), but certainly there are plenty of answers that are wrong (they contradict observations), inconsistent, ambiguous, untestable. And in science you try to get rid of all these answers.
[separate post]
You can not justify faulty argument by constructing a "straw man".
Yes, you didn't follow what I mean, and you repeated your faulty approach because of it. What I mean is you should not be looking for rhetorical logic fallacies because they don't apply in science. They're just too hard to actually create. Keep them in the humanities where they belong.

Specifically: Pointing out that while one set of math fails (to allow an event horizon), a different set of math works (to allow an event horizon) is not a logical [strawman] fallacy. As you correctly pointed out: science is about finding the "best" among competing models.

More direct: Please stop citing supposed logical fallacies. Real scientists don't do that when debating each other because they aren't a "thing" in science. You aren't helping yourself with this tactic.
 
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zonde

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There is nothing cryptic here: this discussion is about the existence or non-existence of the event horizon.
Not exactly. Discussion is about formation of event horizon. These are two related but distinct things: existence of event horizon and formation of event horizon.
There is massive object without event horizon. Then some time later there is "massive object" (region of spacetime) with event horizon. The question is what according to model happens in between.

Ok, it does not seem that this is going anywhere. Your are not accepting my criticism and I am not accepting yours. So I will stop here.
 
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There is nothing cryptic here: this discussion is about the existence or non-existence of the event horizon. The OP assumes its existence in his argument that it can't exist.
I read the the posts of the OP again but didn't find such an argumentation. Can you please quote what you are referring to?
 

russ_watters

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I read the the posts of the OP again but didn't find such an argumentation. Can you please quote what you are referring to?
My mistake: the Opening/Original Poster introduced the idea in post #27, not in post #1. And there are several minor variations of the issue being discussed.
 
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My mistake: the Opening/Original Poster introduced the idea in post #27, not in post #1.
I don't even see it in #27. I read it the same way as zonde. The OP does not assume the existence of a singularity. He concludes that it does not exists because it never forms due to an ever increasing but finit time delation. This argumentation is at least valid for an external observer. And I expect it to be even valid for an observer in the center when Hawking radiation comes into play.
 

russ_watters

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I don't even see it in #27. I read it the same way as zonde. The OP does not assume the existence of a singularity. He concludes that it does not exists because it never forms due to an ever increasing but finit time delation.
I'm not seeing a difference. You can call it "ever increasing but finite", but it "approaches infinity" and the existence of the asymptote is one of the features of that math. It's like saying for y=1/x as x approaches 0, y "approaches infinity" but remains finite. Even if you don't state the existence of the asymptote it is still there, as a feature of the math used in the argument.

And I don't understand why you and apparently zobd think this is an issue: we're not claiming the description is mathematically wrong, however you want to word it!

[edit] Btw, maybe what you really should want to know is why, if the scenarios are similar, did I introduce a slight alteration? I did it because it is cleaner. The changes in the arrangement of matter and simultaneous changes in the shape of the gravitational field are complex and I doubt have even been well modeled. So I think it is easier to visualize a static gravitational field and an object dropping into it. It's the same logic/question applied to a simplified problem.

[edit2] Acually, I would think the moment of creation requires quantum mechanics and general relativity: you'd have to describe something like the gravitational field around two neutrons that collapse into each other and form a tiny black hole. After that, everything else is the scenario I describe(with the addition of a non negligible growth rate).
 
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It's like saying for y=1/x as x approaches 0, y "approaches infinity" but remains finite.
Exactly. And that's something completely different than y=1/x with x=0. Or do you really think that there is no difference between x=0 and x<>0?
 

russ_watters

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Exactly. And that's something completely different than y=1/x with x=0. Or do you really think that there is no difference between x=0 and x<>0?
I'm saying that the equation describes both, whether someone mentions both or not. And again I ask: why are we splitting this hair?
 
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And again I ask: why are we splitting this hair?
Because that's the topic. The argumentation of the OP means in your analogy above, that x will never reach the singularity x=0.
 

russ_watters

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Because that's the topic. The argumentation of the OP means in your analogy above, that x will never reach the singularity x=0.
That's not an answer to my question. I'm asking what relevant difference there is that makes one description useful and the other not.

It's like we're discussing the speed of a pink racecar and you are arguing that it is salmon, not pink. So what? What does that have to do with the issue being discussed?
 
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OP does not say or suggest that he considers infinite time dilation as absurd. He said that ever increasing finite time dilation
That is infinite. Infinite means that if you pick any finite number, it gets bigger.

You can not justify faulty argument by constructing a "straw man".
I don’t think that I am. I think that you are misunderstanding the OP’s argument.
 
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These are two related but distinct things: existence of event horizon and formation of event horizon.
But the specific “absurdum” argued applies equally to both. The argued “absurdum” is infinite time dilation which occurs just outside the event horizon regardless of whether you are talking about Schwarzschild or OS.
 

zonde

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But the specific “absurdum” argued applies equally to both. The argued “absurdum” is infinite time dilation which occurs just outside the event horizon regardless of whether you are talking about Schwarzschild or OS.
In Schwarzschild solution infinite time dilation occurs at finite proper time of infalling particle. It is not obvious that by analogy adopting proper time of particle at the center of collapsing body would be a good strategy in case of OS solution. Say distant observer is observing two different massive bodies shortly before gravitational collapse that have different gravitational time dilation at the center of the body. There is no reason to prefer time at the center of one body over the time at the center of the other body. But if we would try to adopt coordinate chart where each center of the body runs at it's own proper time we would accumulate time difference over time (for static bodies). So the obvious choice for distant observer is to keep his own time for coordinate chart. But in that chart infinite time dilation for collapsing body would be reached at infinite future of this coordinate chart or in plain English - never.
Alternatively you could try to adopt simultaneity that depends on dynamics of collapsing body. But this is highly non-trivial and besides it might lead to break point in simultaneity planes at the center of the body. If you try to avoid that it becomes even less trivial.

So the point is that analogy between Schwarzschild and OS regarding infinite time dilation is far from obvious.
 

zonde

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I would like to add that from my previous post it seems that conclusion about physical situation might depend on the size of adopted coordinate chart. This situation is known by more than 2000 years from the time when Zeno came up with Achilles and the tortoise paradox. However philosophers have not reached consensus how the paradox should be solved.
My position is that the right resolution to the paradox is given by Diogenes i.e. (the reasoning of Zeno is sound but) it contradicts observations. It is sort of the thing that in science is taken as obvious: not every correct mathematical model describes reality and therefore we have to test our models against observations.
 
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I'm asking what relevant difference there is that makes one description useful and the other not.
The difference is no singularity in one description and a singularity in the other.
 
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That is infinite. Infinite means that if you pick any finite number, it gets bigger.
That just means that the limit is infinite but not the numbers and we are talking about the numbers.
 
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That just means that the limit is infinite but not the numbers and we are talking about the numbers.
There is no infinite number. Infinite is inherently a limit.
 
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There is no infinite number. Infinite is inherently a limit.
If you know that, why do you claim, that an "ever increasing finite time dilation" "is ifinite"? It always remains finite and defined. And no matter how big the number is, almost all positive numbers are bigger.
 
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It is not obvious that by analogy adopting proper time of particle at the center of collapsing body would be a good strategy in case of OS solution.
I agree, so I would not pick that point. I would stay away from the center because that is where the singularity is and we expect our models to break down there. So pick another point where we expect the model to work, and all I said above applies.

We also do not pick the center of the Schwarzschild solution, so I was not even considering picking the center of the OS solution.

But in that chart infinite time dilation for collapsing body would be reached at infinite future of this coordinate chart or in plain English - never.
Yes, this is understood. Hence the OP’s “absurdum” and then the rebuttal follows validly pointing out that the observer’s coordinate chart doesn’t change the local physics at all.

So the point is that analogy between Schwarzschild and OS regarding infinite time dilation is far from obvious.
That is only because you are choosing a bad point to examine. Outside the singularity at the center the analogy is good. I was considering a point away from the singularity.

I think that is the source of our disagreement.
 
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