There IS no interior of a black hole

M

Mike_Fontenot

Registered Senior Member
One of the "made my day" moments in my life was when I had been studying Schwarzchild's GR solution for a spherical non-rotating massive object. He gets a quadratic equation, and its two solutions are almost universally interpreted as being the exterior and interior of a black hole. But I didn't (and don't) think that was right: I thought that (as often happens in physics) only one of the two quadratic solutions applied to the problem at hand, and the other was just a spurious mathematical result with no physical significance. So with my interpretation, there IS nothing beyond the event horizon. I expressed that view on a moderated usenet group ("foundations", which no longer exists), and said that I realized I was in the tiny minority in that view. The moderator told me I was in good company, though ... Dirac had published a paper in the mid 60's concluding the same thing. The moderator gave me an on-line link to his paper, and I read it, and confirmed that our views were the same. If Dirac ever changed his mind, I'm not aware of it.
 
Why do you think there is nothing beyond the event horizon? Do you think the dense matter that gives rise to the black hole suddenly disappears? You think it is a hold of... nothing? How does the "nothing" create the super-dense environment?
Might it not be the case that the solutions are, while mathematically distinct, actually causally related: one solution relies on the existence of the other? Physical reality being a case of either no solution or both?
 
Sarkus said:
Why do you think there is nothing beyond the event horizon? Do you think the dense matter that gives rise to the black hole suddenly disappears?
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I think the mass of the black hole is distributed over the surface of the event horizon. The black hole has no volume!
 
Is the core of anything really all that dense?

objects could easily be flung by the core and land in the “mantle” so to speak.
 
Mike_Fontenot said:
I think the mass of the black hole is distributed over the surface of the event horizon. The black hole has no volume!
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The event horizon of a Schwarzschild black hole is a sphere. If the surface area of that sphere is not zero, then the volume enclosed by that sphere cannot be zero either. (In fact, the Schwarzschild solution says, in effect, that the volume of space inside the event horizon will be larger than the volume enclosed by a sphere of the same radius in a flat spacetime.)
 
James R said:
The event horizon of a Schwarzschild black hole is a sphere. If the surface area of that sphere is not zero, then the volume enclosed by that sphere cannot be zero either. (In fact, the Schwarzschild solution says, in effect, that the volume of space inside the event horizon will be larger than the volume enclosed by a sphere of the same radius in a flat spacetime.)
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You may be right ... my memory about all that is very fuzzy now. I've tried to reproduce my conclusions about black holes from long ago, and haven't been able to find the equations that I used when doing that work. What I DO remember is, after doing my work, I read a paper by Dirac that concluded the same thing. I've tried to find that paper, but haven't been successful. It was published in 1962, when Dirac had left Cambridge and was a professor at Florida State University ... he had come there because that's where his daughter lived then, I think. I don't know if he ever changed his mind about the lack of existence of an interior of black holes, or not. But I THINK his and my conclusion at that time was that, not only is there no MASS inside of the event horizon, there is no space or time in there either. There IS no there.

In your comments above, you said:

"The event horizon of a Schwarzschild black hole is a sphere." I think the correct statement is that the event horizon is a spherical SURFACE.
 
Mike:

If you say there's no mass inside the event horizon, the obvious next question is: where does the mass go when it falls into a black hole?
 
James R said:
Mike:

If you say there's no mass inside the event horizon
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Not only is there no mass inside the event horizon, the IS no "inside" of the event horizon. I.e. there is no SPACE or TIME beyond the event horizon.

James R said:
The obvious next question is: where does the mass go when it falls into a black hole?
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Good question! I THINK the incoming mass must accumulate on the event horizon surface itself. And that would seem to require that the mass accumulates in a finite volume ... i.e., the horizon must become thicker, either growing outward, or else growing inward. Or alternatively, perhaps the mass density could increase indefinitely, and never expand the event horizon in thickness, even though it increases in mass. I don't know if Dirac discussed this issue in his 1962 paper. I can't find that paper anymore, either in my personal collection or online.
 
Mike_Fontenot said:
Not only is there no mass inside the event horizon, the IS no "inside" of the event horizon. I.e. there is no SPACE or TIME beyond the event horizon.
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This looks remarkably like you are saying you know what is inside an event horizon. So, do you?

Isn't a lightcone rotated so that space and time switch places, inside the horizon?
 
arfa brane said:
This looks remarkably like you are saying you know what is inside an event horizon. So, do you?
Mike_Fontenot said:
Not only is there no mass inside the event horizon, the IS no "inside" of the event horizon. I.e. there is no SPACE or TIME beyond the event horizon.
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I think the above quote by me says that I (think I) know that there is NOTHING inside the event horizon, not even any space or time ... i.e., that that volume simply doesn't exist.

arfa brane said:
Isn't a lightcone rotated so that space and time switch places, inside the horizon?
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It is true that the variables "r" and "t", that Schwartzchild used in his derivation, switch roles inside the event horizon: outside, "r" is the spacial coordinate, and "t" is the time coordinate. Inside (according to Schwartzchild) "r" is the time coordinate, and "t" is the spatial coordinate. That switch is what convinced Dirac and me that the "inside" solution was spurious and not a real solution, just as one of the two solutions of a quadratic equation in physics is often an artifact and non-physical.[/QUOTE]
 
I'm curious what you think an infalling observer will experience as they approach and cross the event horizon of a super massive black hole.

The gravitational gradient at the event horizon of a sufficiently large SMBH is very small - quite survivable, so they won't be pulled apart. They won't even know they're crossing it, unless they calculate where its radius should be. It's a continuum; nothing about their environment will herald the moment of the crossover itself.

What do you think they will experience? Are you suggesting they will flatten on the outer shell of the EH? What force would cause that?
 
DaveC426913 said:
I'm curious what you think an infalling observer will experience as they approach and cross the event horizon of a super massive black hole.

The gravitational gradient at the event horizon of a sufficiently large SMBH is very small - quite survivable, so they won't be pulled apart. They won't even know they're crossing it, unless they calculate where its radius should be. It's a continuum; nothing about their environment will herald the moment of the crossover itself.

What do you think they will experience? Are you suggesting they will flatten on the outer shell of the EH? What force would cause that?
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First of all, keep in mind that I haven't worked on black holes in MANY years, and I haven't been able to find any of my own notes or Dirac's 1962 paper (either in my collection or online). So my recollections are fuzzy. But with that warning, my answer is that infalling observers will spatter themselves on the surface of the event horizon. They will join the collection of mass that has been accumulating there ever since the black hole came into existence.
 
Mike_Fontenot said:
First of all, keep in mind that I haven't worked on black holes in MANY years, and I haven't been able to find any of my own notes or Dirac's 1962 paper (either in my collection or online). So my recollections are fuzzy.
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OK, so you don't know.

Why continue with your assertion when it's indefensible?

Mike_Fontenot said:
But with that warning, my answer is that infalling observers will spatter themselves on the surface of the event horizon. They will join the collection of mass that has been accumulating there ever since the black hole came into existence.
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Why, from the reference frame of the infalling observer, would that happen? What force would they observe that would prevent them from falling freely, just as they have been doing?

Your physics must be consistent from the POV of both reference frames: the external observer's and the infalling observer's. You pretend like the infalling observer's experience does not exist. That's a problem with your hypothesis.


An even simpler question. By your hypothesis, they are now suspended some distance above an unstoppable gravitational pull. What is holding them there? What is this surface made of that it can hold itself up against such unstoppable gravity?
 
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DaveC426913 said:
OK, so you don't know.
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I'm just telling you what I believed then. And I'm telling you what Dirac believed then.

Why continue with your assertion when it's indefensible?
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It's not indefensible.

Why, from the reference frame of the infalling observer, would that happen? What force would they observe that would prevent them from falling freely, just as they have been doing?
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The same force that stops moving masses when they hit a much larger mass.

Your physics must be consistent from the POV of both reference frames: the external observer's and the infalling observer's. You pretend like the infalling observer's experience does not exist.
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No, I'm telling you what the infalling observer experiences (as much as an almost instantaneous "splat" can be experienced). In the view of a distant observer, nothing falling toward a black hole ever gets there.

An even simpler question. By your hypothesis, they are now suspended some distance above an unstoppable gravitational pull. What is holding them there? What is this surface made of that it can hold itself up against such unstoppable gravity?
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No, they are "splatted" on the spherical surface of the event horizon. They (and the rest of the mass from all the previous "splattees") are held there by the gravitational attraction of all that accumulated mass. And none of that mass can go anywhere, because there is no where to go in that direction (because there is NOTHING inside that spherical surface ... no mass, no space, and no time ... the inside doesn't exist.
 
Mike_Fontenot said:
It's not indefensible.
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Then defend it.

Nothing you say that follows is a defense. You are simply a re-asserting the same belief that is based on an unfounded premise, as I address below.



Mike_Fontenot said:
In the view of a distant observer, nothing falling toward a black hole ever gets there.
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Yes. In the view of a distant observer. That's a frame-dependent observation. That doesn't say anything about what the infalling observer experiences. Relativity - both SR and GR - is premised on the idea that two observers don't have the same experiences or observe the same things. So your conclusion about what the infalling observer experiences is unfounded.

Mike_Fontenot said:
... there is NOTHING inside that spherical surface ... no mass, no space, and no time ... the inside doesn't exist.
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This is the part that's indefensible. And the rest of your hypothesis is balanced on it.

An observer falling into a supermassive black hole experiences no abrupt change between outside the EH and inside the EH. The BH is large enough that the gravitational gradient can be quite survivable. The event horizon itself is a purely abstract boundary - just a radius - and there is nothing the infalling observer can see that will tell them the difference between the moment they are about to cross it and the moment after they cross it.

Your claim that "there is nothing inside the EH" is currently entirely unsupported and is not consistent with known physics that applies here. There is no reason to assume that known physics stops applying at the EH - it's exactly the same physics just below the EH as it is just above.

The only place our physics is inadequate is at the singularity itself - where we have no models for mass that compacted.
 
Mike_Fontenot said:
I'm just telling you what I believed then. And I'm telling you what Dirac believed then.



It's not indefensible.



The same force that stops moving masses when they hit a much larger mass.



No, I'm telling you what the infalling observer experiences (as much as an almost instantaneous "splat" can be experienced). In the view of a distant observer, nothing falling toward a black hole ever gets there.



No, they are "splatted" on the spherical surface of the event horizon. They (and the rest of the mass from all the previous "splattees") are held there by the gravitational attraction of all that accumulated mass. And none of that mass can go anywhere, because there is no where to go in that direction (because there is NOTHING inside that spherical surface ... no mass, no space, and no time ... the inside doesn't exist.
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I can't understand how that can work, since it seems to rely on matter already accumulated on this surface. But immediately after the black hole forms, there is no matter there. So what stops the first piece of matter to arrive? It can't be other matter, as there isn't any, yet. As Dave says, the only force acting is the gravitation from the singularity at the centre. So the matter will be accelerated in, surely?
 
exchemist said:
I can't understand how that can work, since it seems to rely on matter already accumulated on this surface. But immediately after the black hole forms, there is no matter there. So what stops the first piece of matter to arrive? It can't be other matter, as there isn't any, yet. As Dave says, the only force acting is the gravitation from the singularity at the centre. So the matter will be accelerated in, surely?
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I no longer remember anything about the process of formation of a black hole, so I can't address your above arguments. However, I'm fairly sure that Dirac, when he wrote his 1962 paper, WAS familiar with the way black holes form, and that knowledge didn't keep him from concluding that there is nothing inside the event horizon of a black hole. What I don't know is whether he ever changed his mind about his conclusions in his 1962 paper.
 
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