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...
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