<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>whopkins@csd.uwm.edu (Alfred Einstead) writes:\n\n> More correctly, mass = gravitational charge is exactly what the Principle\n> of Equivalence says, and that _therefore_ that energy and momentum are the\n> source of gravity.\n\nThe Equvalence Principle says that inertial mass equals gravity-affected\nmass, but it says absolutely nothing about the relation between\ngravity-affected mass and gravity-generating mass (and it had better\nnot, since there isn\'t any gravity-generating mass in GR). Anyway, you\ncan\'t possibly hope to derive the fact that the electromagnetic field\ngenerates gravity from that argument, since photons are massless.\n\n--\nEsa Peuha\nstudent of mathematics at the University of Helsinki\nhttp://www.helsinki.fi/~peuha/\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>
whopkins@csd.uwm.edu (Alfred Einstead) writes:
> More correctly, mass = gravitational charge is exactly what the Principle
> of Equivalence says, and that _therefore_ that energy and momentum are the
> source of gravity.
The Equvalence Principle says that inertial mass equals gravity-affected
mass, but it says absolutely nothing about the relation between
gravity-affected mass and gravity-generating mass (and it had better
not, since there isn't any gravity-generating mass in GR). Anyway, you
can't possibly hope to derive the fact that the electromagnetic field
generates gravity from that argument, since photons are massless.
--
Esa Peuha
student of mathematics at the University of Helsinki
http://www.helsinki.fi/~peuha/