Damon said: > So essentially, you could plant a wormhole opening on a ship, send > it thousands of LY away, but if the subjective time on the ship is > only a few years to reach the destination, then a space-faring > civilization could theoretically spread throughout the galaxy in > the space of a few decades or even centuries?
Yes, that's exactly right, although your terminology is a little different to that used by physicists. It's not really the "subjective" time on the ship because it's actually an *objective* time. The only time that has any physical meaning independent of the chosen coordinate frame is the time as measured by clocks (the "proper time"), and that time applies only to the path along which the clock travelled. There's no difference in objectivity whatsoever between the clocks on the ship and on Earth. The problem only arises because we naively think we can say which events at the destination happen at the "same time" as any particular event at home. But in fact we cannot do so in any physically meaningful way. > But its not really time travel (or at least not the cool kind where > you could talk to your great grandpa when he was your age) because > the displacement is in both time AND space? > > Heh. Almost seems TOO easy... The difficulty arises if the colony sends a wormhole back to Earth. Then it's possible to make a path from the future of Earth to its past, and so to violate causality. (You can do this with a single wormhole too, just by sending one of its mouths out and then bringing it back.) The smart money seems to be on wormhole networks in this situation being overloaded with quantum fluctuations and collapsing just as they would otherwise form a time machine. > Now, I have to fill the backstory of a technologically advanced, > wormhole using civilization completely and utterly collapsing, so > that Humans (and alien "successor" races) can stumble on that > wormhole network... That was more or less the secret plot in my Ad Astra rpg: http://www.theculture.org/adastra/ You might also like my sketch of the background for an as yet unwritten novel about universe-spanning wormhole networks: http://www.culturelist.org/cdr/article.cfm?id=35 Rich _______________________________________________ http://www.mccmedia.com/mailman/listinfo/brin-l
