Are black holes really infinitely dense or just VERY VERY VERY x10^839401 VERY dense?

Question

I have heard black holes are infinitley dense, but I have recently heard for a black hole to be infinitley dense its constituent matter would have needed to travel faster than light so infinite density goes against Einstein's relativity. I mean in the 2-D trampoline like representation of space-time that is used to explain gravity does a black hole actually break through the plain or does is just a very very deep hole?

The VERY VERY VERY x10^839401 VERY dense idea sounds much more intuitively plausible to me.

Answer 1

General Relativity predicts that the singularity is, in fact, infinitely dense.

There is no a priori reason why this should not be so, but we do strongly suspect that GR is invalid at the quantum level. So the upshot is that the theory says one thing, but we don't really believe it for such a small length scale. Most physicists believe that quantum gravity will yield a finite size and density for the black hole.

Answer 2

Einstein was not very sharp.  He did  not understand that space has no limits at all, not even in time or volume.  In fact, Einstein did not even know how to tie shoelaces.  He always wore slippers and loafers.  

Since black holes are not here with us, it is futile to think about them.  Concentrate on getting good grades in math and english and physics and chemistry and develop cars which do not use gasoline.

Space-out Space and Space-in reality.

Answer 3

This is a question we really can not know the answer to.  This exists inside the event horizon, so no information, no observations are possible.  In some theories the matter is squeezed down to zero volume, which would give infinite density, but since no other true infinities have ever been found to exist other than in concept, my personal opinion is that the collapse does stop before reaching zero volume.

Answer 4

To have infinite density, you would need to have infinite mass.  Or, some mass confined within an infinitely small space.  

If it had infinite mass, then it seems logical to me that due to gravity, either no black holes exist, or any black hole that did exist would have already attracted all other mass from the universe into it.

If it was simply something with some mass (less than infinite) but confined into an infintely small space, I don't see how the human mind can comprehend this...  how can anything exist if the space it is contained within have zero volume?

Logic suggests, to me anyway, that it's just an extremely dense object, that approaches the infinity.  Or, we just don't have all the physics of the universe hammered out just yet.

Answer 5

I guess nobody knows.

Answer 6

General Relativity (GR) works on large scales (for example, larger than a few centimeters).   Using GR equations for things smaller than 1 mm is just plain wrong.

Quantum Mechanics (QM) works for things up to a few cm in size (and in some cases even larger).  Among other things, QM shows that things can't be smaller than than about 10^-35 meters.  But the equations don't work when gravity is significant.

So far, nobody has been able to combine GR and QM.  That needs to be done to understand what things might be like inside a black hole.  Personally, I suspect that the "singularity" of a black hole is bigger than 10^-35 meters, and the density is therefore very large but not infinite.

Your number of 10^839401 (kg / m^3 ?) is WAY to big, however.  A value of about 10^120 or 10^140 is more realistic.

Answer 7

I don't know. Maybe there's such a thing as the "Planck density" that can't be exceeded, which would mean that instead of singularities black holes would contain quantum systems obeying some peculiar rules of quantum gravity.