mouse@mcgill-vision.UUCP (der Mouse) (11/22/85)
[[ This is getting off of space issues, so I am cross-posting to net.physics and directing followups to net.physics only. For net.physics people, this started in net.space. ]] OK, since nobody else responded (or is news just slow to here?) >> The difference in the rate at which time passes for two different inertial >> frames of reference is determined by the Lorentz Transformation: >> --------- >> / v**2 v = Velocity of one frame with respect to >> \ / 1 - ---- the other. >> \/ c**2 c = Speed of light. >> > What happens if two ships leave with opposite vectors, and they both > approach the speed of light relative to their initial frame. The v > above, relative to each other, would approach 2*c, giving a non-real > answer. Where am I goofing? (Or is it time to invest in a FTL ship? > :-) "v = Velocity of one frame with respect to the other". That is, as observed by an observer attached to the other (frame). The velocity of frame X as observed by (an observer in) frame Y is (necessarily) less than c, so the result doesn't go imaginary. The 2c velocity is obtained by measuring from a third intertial frame; if you want to get results for two frames based on quantities observed in a third, you have to use more complicated equations. -- der Mouse USA: {ihnp4,decvax,akgua,etc}!utcsri!mcgill-vision!mouse philabs!micomvax!musocs!mcgill-vision!mouse Europe: mcvax!seismo!cmcl2!philabs!micomvax!musocs!mcgill-vision!mouse Hacker: One responsible for destroying / Wizard: One responsible for recovering it afterward