(sanman) writes:

I think I get what a Black Holes is, but what's a gravastar?

http://www.sciam.com/article.cfm?cha...6A80A84189EEDF

It is exactly what the article says it is: A maverick alternative theory to
black holes that assumes that the field equations of General Relativity
break down under the conditions where they claim a black hole _would_ have
formed, and that spacetime converts into something else even more wild and
bizarre inside a black hole. (Did you bother to read the entire article?)

Under the theory of these mavericks, event horizons don't exist, and instead
of an immaterial horizon that has no physical effect on you when you cross it,
there would be a "physical" surface at the Schwarzschild radius against which
you *would* have gone "splat" --- except that since the "rate of time" slows
to ZERO at the "gravastar's" surface, you can never actually _get_ there to go
"splat" against it.

Quite bluntly, virtually no one in the physics community takes this
"gravastar" idea AT ALL seriously, except its originators and a few
other crackpots who find the idea of "black holes" either "paradoxical"
or esthetically distasteful.


I've read about putative claims of black hole sightings, but has a
gravastar ever been seen?

According to the theory, it is probably IMPOSSIBLE to distinguish between
a "gravastar" and a black hole, except perhaps in the "dark horse" case
that the two theories make different predictions for the spectrum of
Hawking radiation produced --- and since it is probably impossible to
detect Hawking radiation from anything except a microscopic black hole,
the odds are high that even this "prediction" couldn't be verified
using remote instrumentation.


And yeah, how do the Einstein school of believers account for the loss
of information into the Black Hole? Can information be lost, and why
or why not?

Classically, information will be lost every time something crosses the
event horizon, since classically, nothing can escape a black hole unless
one allows bizarre and probably unphysical possibilities such as "tachyons"
or "warp drives."

Quantum mechanically, no one knows WHAT might happen, since as yet there is
no quantum theory of gravity. Some people believe the information will be lost,
and other people believe it will be preserved as non-thermal correlations
between Hawking radiation particles. Until there is a viable theory of
quantum gravity, no one can say which viewpoint is likely to be right.


-- Gordon D. Pusch

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