Relay-Version: version B 2.10 5/3/83; site utzoo.UUCP Posting-Version: version B 2.10.1 6/24/83; site bonnie.UUCP Path: utzoo!watmath!clyde!bonnie!emh From: emh@bonnie.UUCP (Edward M. Hummel) Newsgroups: net.physics Subject: A cosmology/relativity question Message-ID: <330@bonnie.UUCP> Date: Sun, 16-Dec-84 17:02:39 EST Article-I.D.: bonnie.330 Posted: Sun Dec 16 17:02:39 1984 Date-Received: Mon, 17-Dec-84 03:25:55 EST Distribution: net Organization: AT&T Bell Laboratories Whippany NJ Lines: 27 <> I haven't been following the latest trends in cosmology very closely, but I recall hearing something about parts of the universe being "unobservable" that seems a bit puzzling. I'm very fuzzy on the details and would appreciate it if someone could correctly state the idea. Here goes.... In the "big bang" theory (e.g. new inflationary universe version) regions of the universe are speeding away from other regions at very high speeds. As per Hubbles law the parts 'farthest' from us are travelling away from us at very high velocities. The puzzling thing is that there are parts which are so far away that light from them has not had enough time to reach us (the universe being only 12 billion years old). This implies that they are outside of a 'light cone' centered at our present. If this is now true, then it must have always have been true. I.e. matter can not outrun the light cone. How is this reconciled with the very small size of the "universe" at t=0 ? What does it imply about the structure within the initial singularity? Comments, answers, further questions appreciated. Thanks, Ed Hummel ..ihnp4!clyde!bonnie!emh