Tim S
Apr7-04, 08:55 AM
<jabberwocky><div class="vbmenu_control"><a href="jabberwocky:;" onClick="newWindow=window.open('','usenetCode','toolbar=no, location=no,scrollbars=yes,resize=yes,status=no,wi dth=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>on 04/04/2004 1:36 pm, John Anderson at ande452@attglobal.net wrote:\n\n>\n> Tim S wrote:\n>\n>> on 24/03/2004 10:19 pm, Daryl McCullough at daryl@atc-nycorp.com wrote:\n>>\n>>> Another General Relativity issue that I\'m a little confused about is\n>>> the time coordinate for events inside an event horizon. In terms of\n>>> the Schwarzchild coordinate t, at what time does an infalling observer\n>>> reach the singularity at r=0?\n>>\n>> Inside the horizon, t is spacelike, r is timelike...\n>>\n>> So the observer reaches the singularity at time r=0.\n>>\n>\n> There\'s a coordinate singularity at the horizon in\n> Schwarzschildcoordinates. There\'s no real singularity. Therefore, it\'s\n> wrong to use Schwarzschild coordinates inside the horizon.\n> They aren\'t valid inside the horizon.\n\nThey aren\'t valid _on_ the horizon (t isn\'t defined).\n\nThey are perfectly valid inside the horizon.\n\n>\n> Use Kruskal coordinates which, are not singular at the horizon,\n> to relate what\'s going on inside and outside.\n\nOr any of a bunch of other coordinate systems that are not singular at the\nhorizon, yes.\n\nTim\n\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>on 04/04/2004 1:36 pm, John Anderson at ande452@attglobal.net wrote:
>
> Tim S wrote:
>
>> on 24/03/2004 10:19 pm, Daryl McCullough at daryl@atc-nycorp.com wrote:
>>
>>> Another General Relativity issue that I'm a little confused about is
>>> the time coordinate for events inside an event horizon. In terms of
>>> the Schwarzchild coordinate t, at what time does an infalling observer
>>> reach the singularity at r=0?
>>
>> Inside the horizon, t is spacelike, r is timelike...
>>
>> So the observer reaches the singularity at time r=0.
>>
>
> There's a coordinate singularity at the horizon in
> Schwarzschildcoordinates. There's no real singularity. Therefore, it's
> wrong to use Schwarzschild coordinates inside the horizon.
> They aren't valid inside the horizon.
They aren't valid _on_ the horizon (t isn't defined).
They are perfectly valid inside the horizon.
>
> Use Kruskal coordinates which, are not singular at the horizon,
> to relate what's going on inside and outside.
Or any of a bunch of other coordinate systems that are not singular at the
horizon, yes.
Tim
>
> Tim S wrote:
>
>> on 24/03/2004 10:19 pm, Daryl McCullough at daryl@atc-nycorp.com wrote:
>>
>>> Another General Relativity issue that I'm a little confused about is
>>> the time coordinate for events inside an event horizon. In terms of
>>> the Schwarzchild coordinate t, at what time does an infalling observer
>>> reach the singularity at r=0?
>>
>> Inside the horizon, t is spacelike, r is timelike...
>>
>> So the observer reaches the singularity at time r=0.
>>
>
> There's a coordinate singularity at the horizon in
> Schwarzschildcoordinates. There's no real singularity. Therefore, it's
> wrong to use Schwarzschild coordinates inside the horizon.
> They aren't valid inside the horizon.
They aren't valid _on_ the horizon (t isn't defined).
They are perfectly valid inside the horizon.
>
> Use Kruskal coordinates which, are not singular at the horizon,
> to relate what's going on inside and outside.
Or any of a bunch of other coordinate systems that are not singular at the
horizon, yes.
Tim