Re: A partial black hole?

sigidunum@[EMAIL PROTECTED]
 wrote:

> Granted that nothing can escape an event horizon, some other questions
> do come to mind.
> 
> -- If two black holes merge, what would a hypothetical observer inside
> the event horizon of one of them see?  If you're falling into
> Singularity A, can your course be shaped to fall into Sing B?

I don't know.  I doubt it.

> -- Spinning black holes supposedly have ring-shaped singularities.  I
> assume there's still no way to avoid falling into the singularity?

You can avoid hitting the singularity, but you still have to pass 
through it, which means you experience infinite blueshift, which 
destroys you anyway.

> -- So you fall into a (very large) black hole and look inwards towards
> the singularity.  What do you see?

The incidental matter that was in front of you before you fell in (as it 
fell in too).

> As the matter that creates the singularity contracts, presumably it
> would heat up, causing it to radiate.  As its density increased
> endlessly, so would its temperature, and the frequency of the
> radiation emitted.  On the other hand, its intense gravitational field
> would tend to redshift and trap EM radiation.  Which effect would
> dominate?  (Or is it even possible to say?)

Causes redshift according to whom?  To radially distant observers (who 
are still inside the horizon), maybe, but they're falling in too, so 
that hardly matters.  Observers outside of the black hole see nothing. 
 From the frame of the thing falling in and heating up, no redshift 
takes place.  From the frame of a hypothetical observer at the 
singularity, things get infinitely blueshifted, but then again, there 
can be no such observer.  So it sounds like your question is ill-formed.

> Also, how would the "singularity always ahead of you" effect appear to
> our hypothetical free-falling observer?  Would the singularity seem to
> be everywhere at once, filling the sky?  Or would it simply be
> unavoidable -- no matter how you fire your rocket, you end up falling
> towards it?

The singularity pretty much by definition is a place where all timelike 
and lightlike paths end.  Once a worldline hits the singularity, nothing 
more can happen.  Thus no photon can ever go from the singularity 
radially outward, even if the spacetime allowed it (which the inside of 
a black hole does not).  The singularity is not visible, even once 
inside the event horizon.

> As you got closer to the singularity -- putting aside
> spaghettification issues, at least for as long as possible -- would
> its appearance change?

You never see it, no matter what you do.  But it quickly kills you.

-- 
Erik Max Francis && max@[EMAIL PROTECTED]
 && http://www.alcyone.com/max/
  San Jose, CA, USA && 37 18 N 121 57 W && AIM, Y!M erikmaxfrancis
   Love is the selfishness of two persons.
    -- Antoine de la Salle