From: utzoo!decvax!ucbvax!mhtsa!eagle!harpo!ihps3!ihnss!knudsen Newsgroups: net.space Title: Supernova, Gravity, Etc Article-I.D.: ihnss.126 Posted: Thu Aug 5 15:16:18 1982 Received: Sun Aug 8 07:34:40 1982 HOLD IT! Basic hih-school physics states that the center of mass of an object cannot change (or its net momentum change) merely thru action of forces generated WITHIN that object -- rather, OUTSIDE forces are required. The example often used is a hand grenade flying thru outer space; if it explodes, the center-of-gravity/mass of all the fragments (& gases, etc) continues to move as before. Substitute a star for the grenade, comes the supernova explosion, and, presto, the center of mass stays ewhere it was. I think someone was wondering how much mass of the star would be changed into ENERGY a la E=mc^2, which *would* cause an instant change in mass. This change is radically different from the percentage of star matter that is merely blown away into space -- probably the 50~90% guesses are close. PS: If matter and energy are the same thing, and you have a volume of space with a VERY high energy flux, does it exert gravity (ie, distort space around it)? --mike knudsen ihnss!knudsen