Darren New <dne### [at] sanrrcom> wrote:
> Warp wrote:
> >   As far as I know, the universe is *expanding*, not going towards a single
> > point.

> If there's enough mass, then eventually gravity will pull everything 
> into a "single point", just like everything came from a single point 
> during the big bang. (At least, that's my lay understanding.)

  Even if that was so, it still doesn't mean we are inside a black hole.

  Anyways, it seems that this is not so after all.

> >   A star is not a black hole even during its own collapse. Not until it
> > gets inside its own Schwarzschild radius. Collapse does not mean that
> > the thing which collapses is a black hole.

> I'm not sure "Schwarzschild radius" makes sense in the context of "all 
> of space-time".

  Why not? The Schwarzschild radius of a given mass is simply a distance
which is the product of the mass and a constant. The Schwarzschild radius
of the universe is the mass of the universe times a that constant.

  If all the mass of the universe was compressed inside a volume smaller
than a sphere with that radius, it would form a black hole.

>  I.e., what does "radius of the universe" mean?

  It's not the "radius of the universe". It's the Schwarzschild radius.
Different thing.

-- 
                                                          - Warp

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