Re: Does anything ever fall inside a black hole.
<jabberwocky><div class="vbmenu_control"><a href="jabberwocky:;" onClick="newWindow=window.open('','usenetCode','toolbar=no,location=no, scrollbars=yes,resizable=yes,status=no,width=650,height=400'); newWindow.document.write('<HTML><HEAD><TITLE>Usenet ASCII</TITLE></HEAD><BODY topmargin=0 leftmargin=0 BGCOLOR=#F1F1F1><table border=0 width=625><td bgcolor=midnightblue><font color=#F1F1F1>This Usenet message\'s original ASCII form: </font></td></tr><tr><td width=449><br><br><font face=courier><UL><PRE>>From 1999 July 3\n\n>Since a black hole will evaporate in finite coordinate\n>time -- while the falling object is still just outside\n>the event horizon -- doesn\'t this mean the object never\n>gets inside the event horizon before the black hole is\n>gone?\n>\n>[Moderator\'s note: No, actually it does get in, at\n> least according to the best analyses of people who work\n> on this stuff. The Relativity FAQ\'s section on black\n> holes talks about this exact case, since my desire to\n> learn the resolution of this apparent paradox was my\n> motivation for studying enough about black holes to write\n> that.\n\nThen the FAQ, itself, needs to be modified as the original analysis is\ncorrect. As Hawking, himself, pointed out in June of 2004 -- admitting\nthat after 30 years of thinking otherwise this earlier view supported\nby the moderator was simply wrong -- there isn\'t even a well-defined\nevent horizon in the first place for anything to fall into.\n\nThis should have been realized at the outset. Technically, an event\nhorizon is the boundary of a trapped region. If the black hole is\nevaporating in finite (Schwarzschild) time, there is no trapped region\n-- hence no event horizon. Nothing that falls in stays in, simply\nbecause there is no "in".\n\nThis was also shown more recently in an article posted here or in\nsci.physics (October 2003) which carried out the analysis for an\ninfalling geodesic for a Hawking black hole, assuming the Stefan law.\nThere is a point where the minimum distance from the \'event horizon\'\n(which in reality is nothing more than a local Rindler Horizon) is\nreached and the receding of the horizon begins to outpace the falling\nobject, itself.\n\nThe actual location of the horizon, since it is not well-defined, is\nalso relative -- not only is it defined only at the state level (as\nopposed to the operator level ... since light cones are defined by\ng_{mn} dx^m dx^n = 0, which is only meaningful numerically as\nexpectation values with respect to a state), but it can also be frame\ndependent, as well as location dependent. What one sees from the\nvantage point of asymptotic infinity can be quite different than what\none sees close up. In particular, what may be inside for an observer\nat asymptotic infinity may be outside for a nearby observer.\n\n</UL></PRE></font></td></tr></table></BODY><HTML>');"> <IMG SRC=/images/buttons/ip.gif BORDER=0 ALIGN=CENTER ALT="View this Usenet post in original ASCII form"> View this Usenet post in original ASCII form </a></div><P></jabberwocky>>From 1999 July 3
>Since a black hole will evaporate in finite coordinate
>time -- while the falling object is still just outside
>the event horizon -- doesn't this mean the object never
>gets inside the event horizon before the black hole is
>gone?
>
>[Moderator's note: No, actually it does get in, at
> least according to the best analyses of people who work
> on this stuff. The Relativity FAQ's section on black
> holes talks about this exact case, since my desire to
> learn the resolution of this apparent paradox was my
> motivation for studying enough about black holes to write
> that.
Then the FAQ, itself, needs to be modified as the original analysis is
correct. As Hawking, himself, pointed out in June of 2004 -- admitting
that after 30 years of thinking otherwise this earlier view supported
by the moderator was simply wrong -- there isn't even a well-defined
event horizon in the first place for anything to fall into.
This should have been realized at the outset. Technically, an event
horizon is the boundary of a trapped region. If the black hole is
evaporating in finite (Schwarzschild) time, there is no trapped region
-- hence no event horizon. Nothing that falls in stays in, simply
because there is no "in".
This was also shown more recently in an article posted here or in
sci.physics (October 2003) which carried out the analysis for an
infalling geodesic for a Hawking black hole, assuming the Stefan law.
There is a point where the minimum distance from the 'event horizon'
(which in reality is nothing more than a local Rindler Horizon) is
reached and the receding of the horizon begins to outpace the falling
object, itself.
The actual location of the horizon, since it is not well-defined, is
also relative -- not only is it defined only at the state level (as
opposed to the operator level ... since light cones are defined by
[itex]g_{mn} dx^m dx^n = 0,[/itex] which is only meaningful numerically as
expectation values with respect to a state), but it can also be frame
dependent, as well as location dependent. What one sees from the
vantage point of asymptotic infinity can be quite different than what
one sees close up. In particular, what may be inside for an observer
at asymptotic infinity may be outside for a nearby observer.
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