Re: A partial black hole?

Mike Huskey wrote:
> On Mon, 25 Feb 2008 14:59:14 -0800, Erik Max Francis <max@[EMAIL PROTECTED]
>
wrote:
> 
> 
>> Huh?  What is inside the event horizon is a singularity, and any 
>> recently captured material falling rapidly in to the singularity to be 
>> crushed to infinite density.  There is no internal structure, as
nothing 
>> can sup****t itself once inside the event horizon; it will, and very 
>> rapidly so, fall inward and hit the singularity and be destroyed.
> 
> 
> Let see. Neutron star with escape velocity of .999999999999999999999999
C.
> Compare with a very slightly more massive neutron star with escape
velocity of
> 1.00000000000000000000001 C.

Well, there's no force known which is capable of creating a "neutron 
star" that is that dense, but let's go with it since I understand what 
you mean, at any rate.

> I don't see any difference other than light/radiation can escape from
the
> first, but not the second.

There is a huge difference.  As I said, nothing can sup****t itself once 
inside the event horizon.  This is not because the forces are really 
strong (though they surely are!), but because the structure of spacetime 
inside an event horizon changes in a fundamental way.

Space and time are related in relativity, of course; travelling very 
fast will result in time moving more slowly for you, and so on.  In 
general relativity, this can become more profound as spacetime can 
actually be warped.  Inside the event horizon of a black hole, spacetime 
itself is distorted in such a way that "moving forward in time" is now a 
physical direction, and it's toward the singularity.  You can no more 
hold your position radially from the black hole -- much less move 
radially outward and escape the event horizon -- than you can travel 
backward in time.

What this means is that _anything_ inside the event horizon is rapidly 
destroyed as it experiences tidal forces that literally diverge as it 
approaches the singularity.  A solid, extended object will experience 
massive tidal forces that elongate it radially and compress it 
transversely.  These forces _diverge_ (they literally go to infinity) as 
the object reaches the singularity, so no physical structure can ever 
survive it.  Not only is this process brutal, but it's also fast; for 
one-solar-mass black hole, the longest amount of time a particle that 
enters the event horizon can hold out before slamming into the 
singularity and its own assured destruction is about ten microseconds.

So the two scenarios for these exotic stars (as they can't really be 
neutron stars) you posit are very, very different.  In the former, where 
an event horizon has not formed, the planet is still there, it's just a 
royal ***** to get to and from.  (Here the tidal forces would be 
tremendous as well, of course, but they'd be finite.)  In the latter, 
just a tiny smidgen more mass means that not only can the surface of the 
exotic star can never be seen or heard from again, but it means that 
anything on the surface of the exotic star (and within the event 
horizon) will be utterly destroyed -- even from its own perspective -- 
in the blink of an eye.  Entering an event horizon results in rapid and 
brutal death.

-- 
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
   Freedom is never voluntarily given by the oppressor.
    -- Dr. Martin Luther King, Jr.