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Black Holes & Gravastars



 
 
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  #1  
Old July 14th 03, 06:51 PM
Gordon D. Pusch
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Default Black Holes & Gravastars

(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

perl -e '$_ = \n"; s/NO\.//; s/SPAM\.//; print;'
  #2  
Old July 19th 03, 04:47 AM
Lucky
external usenet poster
 
Posts: n/a
Default Black Holes & Gravastars

could you explain that more simplified?
There are some of us idiots here that dont know english that well.
"Gordon D. Pusch" wrote in message
...
(sanman) writes:

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


http://www.sciam.com/article.cfm?cha...EF-46AA-1F04-B
A6A80A84189EEDF

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

perl -e '$_ = \n"; s/NO\.//; s/SPAM\.//; print;'



  #3  
Old July 21st 03, 09:33 AM
Gordon D. Pusch
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Posts: n/a
Default Black Holes & Gravastars

"Lucky" writes:

could you explain that more simplified?
There are some of us idiots here that dont know english that well.


I'll try, but if you didn't understand the _Scientific American_ article,
I don't think it will help, as the authors of that article are already
using newspaper-level english, i.e., less than 6th-grade level, and I was
writing at a level hardly higher than that.

The authors of the "gravastar" theory claim that "black holes" don't exist,
because they believe Einstein's theory of spacetime fails if spacetime gets
bent too far.

They believe that instead, spacetime turns into something different, that
ISN'T space and ISN'T time and ISN'T matter, so that there isn't any "thing"
there that we would recognize as a "thing" any more, and that nothing else can
possibly penetrate into, because nothing that we would recognize as a "thing"
can possibly exist in such an everything-less non-happening-ness no-place.

Most scientists don't take this crazy idea seriously, because they think it is
even more disgusting than these two guys think the idea of "black holes" is.

There. Did that help ??? I didn't think so...


-- Gordon D. Pusch

perl -e '$_ = \n"; s/NO\.//; s/SPAM\.//; print;'
  #4  
Old July 29th 03, 04:41 PM
Morenga
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Posts: n/a
Default Black Holes & Gravastars


They believe that instead, spacetime turns into something different, that
ISN'T space and ISN'T time and ISN'T matter, so that there isn't any "thing"
there that we would recognize as a "thing" any more, and that nothing else can
possibly penetrate into, because nothing that we would recognize as a "thing"
can possibly exist in such an everything-less non-happening-ness no-place.


Well there a several logical flaws with this idea.
Since everyone agrees that black holes can not be seen by default,
they can only be observed by the effect they are having on their
surroundings.
Mainly gravity that is. Since the gravitational side effects of super massive
(as well as lesser massive neutron stars) are well known by now, this new
approach begs the questions, WHERE DOES THAT GRAVITY COME FROM?

Gravity neccessitates mass, thus if there is no super massive object at the
core,
then why can we still observe its gravity?

Also, even so Einstein himself at first refused to accept this fact, it is
clear that
if light has a finite speed, and also has mass (both assumptions based on
Albert's own theories), that light can indeed be accelerated beyond its own
means of escape if you only pile up enough mass to do so.
And since in Einstein's universe nothing is faster then light, this also
means
that nothing else could get out there. Thus you got a black hole.

It is not for no reason that black holes where already accepted as a
certainty
long before they could ever be observed. Einstein's own workings neccesitate
them!

Indeed, by now we also know that w/o super massive black holes our very
Universe
would not exist as we know it. Galaxies themselves require black holes to
form around them.

Greetings
Morenga


Most scientists don't take this crazy idea seriously, because they think it is
even more disgusting than these two guys think the idea of "black holes" is.

There. Did that help ??? I didn't think so...


-- Gordon D. Pusch

perl -e '$_ = \n"; s/NO\.//; s/SPAM\.//; print;'




 




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