Asri-unix.869 net.space utcsrgv!utzoo!decvax!ucbvax!ARPAVAX:C70:sri-unix!Hans Mon Mar 1 12:31:10 1982 Red vs blue spaceships Fooey, there was a square root dropped in the beam angle calculations of my last note. The aberration in beam angle for a source emitting a narrow beam in the direction of travel should have read: 1 + v Aparent beam angle = Source beam angle * SQRT(-----) 1 - v with v being recession velocity as fraction of c. This means that photon starships moving with the typical quasar velocity of .82 c are only about 100 times as likely to be seen accelerating away from us as decelerating towards us. This is still in plausible agreement with observation since most of the 200 quasars that have been identified were found by looking for large redshift. And if the data should rule out the narrow blue beam possibility in future, we can always fall back on the hypothesis that there are better ways to slow down than using the big engines used for acceleration. ----------------------------------------------------------------- gopher://quux.org/ conversion by John Goerzen of http://communication.ucsd.edu/A-News/ This Usenet Oldnews Archive article may be copied and distributed freely, provided: 1. There is no money collected for the text(s) of the articles. 2. The following notice remains appended to each copy: The Usenet Oldnews Archive: Compilation Copyright (C) 1981, 1996 Bruce Jones, Henry Spencer, David Wiseman.