Chronology Current Month Current Thread Current Date
[Year List] [Month List (current year)] [Date Index] [Thread Index] [Thread Prev] [Thread Next] [Date Prev] [Date Next]

Re: cosmology and quantum gravity



On Fri, 28 Apr 2000, Joel Rauber wrote in part:

Jack wrote in part:
. . .
The static gravitational effects that we can observe are
embedded in the
metric (more strictly, the curvature) outside of the horizon. In the
usual metric, the gravitational effects get larger and larger as we
approach the black hole until they blow up at the horizon,
where there is
a coordinate singularity. . . .
--------------------------------------snip----------------------------

There exist other coordinate systems to describe a Schwarzchild black hole
that have no coordinate singularities at the event horizon. One oft cited
example are the Kruskal-Szekeres coordinates (named after their creators, I
assume) See the book "Gravitation" by Misner, Thorne and Wheeler (know to
many students as MTW) around page 831 for a discussion.

Joel

And, conversely, I would not have put it Joel's way, having
specifically referred to "coordinate singularity" and "event horizon".
I would not get into such technical details as Kruskal-Szekeres
coordinates in responding to a simple, naive question about gravity.
My description was accurate; it spoke of gravitational effects
<in the usual metric>. Since the question was, "how do the gravitational
forces get out" the additional details would seem to be irrelevant to
the question asked.
Regards,
Jack