Intuitively - why aren't black holes hot?

[justsomeguy]

I assume the OP means the singularity, and not "the black hole"; perhaps a problem of definitions as someone else pointed out? Why a black hole is cold from the perspective of an observer outside the event horizon is already well explained in the thread it seems.

I think the error is an assumption the OP has which is built into the question -- s/he assumes that once you are inside the event horizon, you can then 'see stuff' if you look towards the singularity. As I understand it, that isn't the case at all. Not only can nothing escape out from inside the event horizon, nothing can even move in any spatial direction except towards it. The event horizon is just a fancy name for the surface of a volume centered on something (the singularity) which nothing can move away from.

Could be misunderstanding something here of course, but I thought I'd try to be helpful for a first post.

 

[ImaLooser]

Not only can nothing escape out from inside the event horizon, nothing can even move in any spatial direction except towards it.

I would think that every "surface" inside the outermost event horizon is also an event horizon, but spacetime is very weird inside of black holes. IF GR applies -- a big if -- then I'm told that time and space reverse roles, something I do not understand at all. There is a professor at UC Boulder who has done considerable work on this. He has a web sites and some videos of his simulations. He thinks that the black hole acts as an extreme accelerator and the energy inside goes toward some sort of infinity.

 

[justsomeguy]

I would think that every "surface" inside the outermost event horizon is also an event horizon

That's another way of looking at it. It's surfaces, all the way down!

, but spacetime is very weird inside of black holes. IF GR applies -- a big if -- then I'm told that time and space reverse roles, something I do not understand at all. There is a professor at UC Boulder who has done considerable work on this. He has a web sites and some videos of his simulations. He thinks that the black hole acts as an extreme accelerator and the energy inside goes toward some sort of infinity.

Do you have a name or some links? I've heard the turn of phrase in the sense that "the singularity doesn't occupy a point in space, but a point in your future" once you've crossed the event horizon, but I just took that to mean that no matter what you do, you're going to intersect it.

It's just intuitive (to me anyway) that if you can't escape the event horizon once you're inside, you can't even move towards it -- only away from it, and towards the singularity. Same goes for light. If light emitted from something 1mm inside the event horizon can't get out, then it seems obvious that anything 2mm (or 200km) inside can't move outward either.

I blame the confusion in this regard on all the poor little cartoon illustrations showing a spaceman standing on the surface (of what) holding a flashlight pointed up, with the beam going up and then just curving back down into the surface.

 

[ImaLooser]

That's another way of looking at it. It's surfaces, all the way down!
Do you have a name or some links? I've heard the turn of phrase in the sense that "the singularity doesn't occupy a point in space, but a point in your future" once you've crossed the event horizon, but I just took that to mean that no matter what you do, you're going to intersect it.

It's just intuitive (to me anyway) that if you can't escape the event horizon once you're inside, you can't even move towards it -- only away from it, and towards the singularity. Same goes for light. If light emitted from something 1mm inside the event horizon can't get out, then it seems obvious that anything 2mm (or 200km) inside can't move outward either.

I blame the confusion in this regard on all the poor little cartoon illustrations showing a spaceman standing on the surface (of what) holding a flashlight pointed up, with the beam going up and then just curving back down into the surface.

A search on
UC Boulder black hole professor
ought to do it.

 

[Chronos]

Yes, as your first post clarified. Unless I misunderstood the OP - we are concerned with the internal temperature of the black hole - rather than the area surrounding it?

Given that events occurring inside the event horizon are entirely unobservable, is there a point to this line of discussion?

 

[enosis_]

Given that events occurring inside the event horizon are entirely unobservable, is there a point to this line of discussion?

No, it seems a bit redundant. The fascinating thing for me - related to the discussion of temperature - is what happens to the heat/energy as it is consumed into the singularity?

 

[justsomeguy]

No, it seems a bit redundant. The fascinating thing for me - related to the discussion of temperature - is what happens to the heat/energy as it is consumed into the singularity?

The textbook answer is that it's "simply" converted to mass. Keep in mind the singularity isn't a "thing", it's just a word to describe a place where the calculations provided by the theory no longer work.

 

[enosis_]

The textbook answer is that it's "simply" converted to mass. Keep in mind the singularity isn't a "thing", it's just a word to describe a place where the calculations provided by the theory no longer work.

Perhaps the better question might be is this the original state of the converted energy - or a step closer to it?

 

[codex34]

Keep in mind the singularity isn't a "thing", it's just a word to describe a place where the calculations provided by the theory no longer work.

Any theory for gravity based on non scalar mathematics fails at the point of inflection, which is exactly why the author of relativity objected to theories referencing points within the mass radius, once you remove the mass radius from calculations you return to non scalar mathematics, a realm in which only wizards and trolls reside.

Singularities are the problems with mathematical philosophy that physics fails to notice.

 

[Chronos]

Mathematics is the language of physics. Yes, there are mathematical illusions and situations where our models fail to include, or, properly parameterize all of the relevant variables. But, I disagree there is anything philosphical about mathematics.

 

[codex34]

Mathematics is the language of physics. Yes, there are mathematical illusions and situations where our models fail to include, or, properly parameterize all of the relevant variables. But, I disagree there is anything philosphical about mathematics.

So what exactly is differentiation? or infinity? :)
What happens at points of inflection?, what does a change in sign mean?, and how does it apply to any given model?
Black hole theory is a primary candidate for study, objects accelerate to a near complete halt in a very short time below the point of inflection, which is opposite to what an object does above the point of inflection.
The change in sign has no real meaning in mathematics?
Gravitational models would still work if we ignore the maths below the point of inflection, however would they still work if we ignored the maths above the point of inflection?

Mathematics is a shorthand for ideas expressed in natural languages, the language of physics is natural language, sometimes expressed in shorthand form.

 

[Chronos]

So what exactly is differentiation? or infinity? :)
What happens at points of inflection?, what does a change in sign mean?, and how does it apply to any given model?
Black hole theory is a primary candidate for study, objects accelerate to a near complete halt in a very short time below the point of inflection, which is opposite to what an object does above the point of inflection.
The change in sign has no real meaning in mathematics?
Gravitational models would still work if we ignore the maths below the point of inflection, however would they still work if we ignored the maths above the point of inflection?

Mathematics is a shorthand for ideas expressed in natural languages, the language of physics is natural language, sometimes expressed in shorthand form.

Differentiation is mathematically rigorous way of expressing an ordered change. The proper way to treat an event horizon is as an indefinite integral. You can't differentiate an indefinite integral in the way you are suggesting.