I'd like to throw some cold water on the notion that the fastest
traveling replicator takes over the universe. Within our galaxy,
for example, the difference between the speeds .9999c and .99999c
isn't significant. For a trip of 100K light years, the faster
replicator will have a 9 year advantage in arrival time at the
far edge of the galaxy. That's enough for it to control the
star it arrives at, and a couple of nearby ones, but its zone is
limited to a 9 light-year radius. And that extra 9 at the end
of its velocity comes at a high cost: The faster seed must have
three times the energy of the slower, and three times the
(relativistic) mass. The launching system must devote at least
three times the resources to the fast probe, and perhaps a much
larger factor. So the slower system can send at least three
times as many seeds, and they will win more territory. The
fast seeder could try to compensate by heading further out on
the frontier, but there's nothing there: it's already reached
the edge of the galaxy.
This same idea seems to be applicable if "galaxy" is replaced by
"cluster", and "star" by "galaxy". So I don't see the fastest
travelers as being the winners. The optimal speed depends on the
cost of getting speeds near c, which determines the cost/benefit
of faster probes. Since the higher speeds are extremely costly,
the optimum might be .8c.
--- Some other thoughts inspired by the discussion ... Can you speed up a star's burn rate by dumping in carbon? --- John McCarthy (and another person whose name I've dropped) proposed the notion of "captive asteroid" to gradually move the Earth away from the Sun as the Sun warms up in old age. The captive is used to transfer energy and angular momentum from other planets to the Earth, say from Venus and Jupiter. The captive makes repeated close encounters with the planets; each encounter moves a snippet of E and L from the planet to the captive or vice versa. The control effort required on the asteroid is minimized by planning sufficiently far ahead -- a butterfly flaps its wings the right way a few encounters ahead of time for steering. The idea also allows snowballing: you can begin with a boulder operating on mountains to move the mountains, which then move small asteroids, etc. Each step requires the same time scales, a few million orbits (linear in the mass ratio). This might be useful (in the long view) as a way to collide stars. (It seems unlikely to benefit intra-galactic replicators, but might be a way to harvest energy for inter-galactic efforts.) --- We might well be the first intelligent replicators in our light cone, perhaps because evolution took a few lucky turns. We might examine the biologically static periods in our planet's life history for clues as to the hard/slow steps. If we are to believe the conventional wisdom (I'm a skeptic), life originated on the planet within a couple of hundred My after cool-down permitted liquid water. Then cells appeared, and maybe 1Gy later multi-celled organisms. Eventually sex was invented, and "species" became meaningful. Later we get sensors, nervous systems, light detection, and the Queen's Gambit Declined. Maybe the hard steps are hard because they require an anti-Darwinian mutation to be quickly followed by an unlikely triumphant over-compensating mutation. The development of intelligence and civilization doesn't qualify as a slow step here. [Accepting this line of thought requires buying into the notion that these later steps are less probable than the origination of life itself, because they took longer. That's why I'm skeptical.] Rich Schroeppel rcs@cs.arizona.eduReceived on Mon Dec 22 17:26:09 1997
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