Darren New <dne### [at] sanrrcom> wrote:
> Warp wrote:
> >> Not true. They just won't guess what happens at the singularity. It's 
> >> called a singularity because the math breaks down there.
> > 
> >   No, I think it's inside the event horizon. While GR equations tell us
> > what happens if GR holds inside the event horizon in the same way as
> > outside it, it's still speculation.

> Fair enough. Altho people have spoken of time travel via rotating black 
> holes and such, but I suppose that's speculation until someone finds one 
> for sure. :-)

  I think the time travel is related to wormholes. Travelling inside a
wormhole does not imply going inside the event horizon of a black hole.

> >   I think you could clearly see the event horizon regardless of its size
> > because of the way it bends light.

> Yes, but all mass bends light. Even "dark matter". :-)  It's kind of the 
> GR definition of "mass".

  I said "they way it bends light", not "because it bends light".

  No mass is dense enough to bend light like a black hole does because,
obviously, if the mass was dense enough, it would collapse into a black
hole...

> >   Once inside, you are doomed. There's no escaping the singularity.
> > You'll go there no matter what you do.

> Yep. Big Crunch. :-)

  I think the analogy is not correct.

  The Big Crunch means that the universe, ie. space itself, contracts
until everything collapses into a singularity. Contraction of space doesn't
involve objects moving. (This is one of the hardest things to understand
about the expansion (and theoretical contraction) of the universe. One
counterintuitive result of the expansion of the universe is that the
distance between two objects can grow faster than c, which at first sounds
like it would break GR, but this is not so.)

  A black hole doesn't contract. Instead, objects physically move towards
the singularity.

> >   Nothing is going towards a global singularity in the universe. On the
> > contrary, everything is going away from everything else.

> At the moment, yes.

  I can't say for sure, but I have the understanding that anything going
away from the singularity inside the event horizon of a black hole would
be against GR equations.

> (Occasionally I surprise myself with the useless information that sticks 
> in my head. Last week it was the reproductive cycle of jellyfish.)

  Whatever floats your boat. ;)

-- 
                                                          - Warp

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