Density

[InfiniteNow]

Now, while on the topic of black holes, what is the matter within a BH called? I know that matter loses all of its characterizing properties when it gets swallowed by the hole. So there should exist in the hole a single "element" or state of matter. What it it? And what are its properties?

Please, someone correct me if I am mistaken, but...

 

Matter inside a BH is still matter, just behaving under a different set of circumstances. You get down far enough into the BH and our present calculations fall apart.

 

As for matter losing all of it's properties, I think you may be thinking of the idea that once a star has reached the point where it becomes a BH, there are only three pieces of information about that star we can still calculate. The "no hair" theorem. I am not too sure this applies to matter falling into a black hole (losing characteristic properties), but someone please correct me if needed.

 

And it's all energy. :shrug:

[Jay-qu]

Black holes can have a few properties - Mass, spin, charge, entropy and Im not so sure if it is correct to say they have a temperature but depending on size they will emit a certain amount of radiation.

[Qfwfq]

If the density of a black hole is infinite, would that mean that it would have an infinite mass basically. E.g some matter the size of an atom from a black hole would weigh more than the whole of our galaxy. I know this isnt very scientific but potentially would this be the case?

The density of the singularity would be infinite, but this doesn't mean infinite mass.

 

It is however impossible to observe beyond the event horizon and scientifically it makes no sense to say what's what inside the blach hole or to talk about what the innards. It's either the whole thing, including the event horizon, or nothing.

 

For this reason I put the volume of the black hole as being finite, not infinitesimal. What we can observe has the finite volume, and an overall density given by total mass divided by that. That's as far as we can get.

[UncleAl]

How do you get the infinite diametre Unk? :confused: The field? If that's perchance your line, then it goes for any massive object. :xx:

Spacetime curvature near a mass is elliptic geometry. The more gravitation the larger the local curvature. If one were to draw a circle with the mass at its center, as gravitation increases the diameter/circumference ratio increases.

 

Look at the surface of the Earth. The equator is the circle. Is the distance along a line of longitude from equator to pole to equator longer than tunneling through th Earth to the same opposite point?

 

A singularity has escape velocity exceeding lightspeed. Spacetime at the singlulary has unlimited curvature. The circumference of the event horizon is unremarkable. The distance through the black hole past the singularity is infinite.

[Qfwfq]

I see what you mean now Unk, ;), but as far as what we can observe from outside the event horizon we can only say the observed mass is within the sphere having the Schwarzschild radius. Only an observer inside, orbiting the singularity, could say more about the density distribution. And I doubt he would observe it being uniform.

[InfiniteNow]

Only an observer inside, orbiting the singularity, could say more about the density distribution. And I doubt he would observe it being uniform.

Poor bloke wouldn't be able to communicate back to us what he saw anyway. Damn you quantum gravity!!