Autzoo.1478 net.space utcsrgv!utzoo!henry Tue Mar 9 19:32:48 1982 quasars as continous-drive starships There is a problem with this hypothesis: continuous-drive starships are implausible except for IMMENSELY long-distance travel. At high accelerations (e.g. 1G), it takes only a short time to reach relativistic speeds (1G is about c/year), and after that you are wasting fuel and driving up your mass-ratio for very little extra speed. Clearly if quasars are continuous for long periods of time they must use quite low accelerations (the lack of observed drift in Doppler shift also implies a low rate of change of velocity, leading to the same conclusion). The problem with low accelerations, say 0.001G, is that it takes centuries to reach interstellar speeds! For all but very long trips, acceleration time dominates travel time so thoroughly that you are better off using a high-acceleration drive even if it has a lower exhaust velocity (and hence a lower cruising speed for the same mass-ratio) because it gets there sooner! You have to be going a hundred light-years or so before low-acceleration high-exhaust-velocity drives make sense. At shorter distances, even the primitive fusion engines proposed in the Project Daedalus design study get there first -- and those engines will be the state of the art here within a century or less. This has two consequences. If quasars are the long-range ships, where are the short-range ships? If there is enough traffic in this vicinity for that many long-range ships to be visible (over the entire sky, please note, not just one area) then we should be in the middle of an active trading area and should be able to see (and hear!) the short-range traffic. Maybe the answer is that the ships are ALL long-range and are ALL headed away from here because something *REAL BAD* is happening in this area and everybody wants to get as far away as possible. Hmm, maybe some of the game-preserve animals on an obscure little planet around an obscure little sun have gotten out of control... ----------------------------------------------------------------- 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.