From: Dani Eder (danielravennest@yahoo.com)
Date: Fri Jan 20 2006 - 18:17:02 MST
E.g., the prevalence of small
> asteroids, etc., might be high
> enough that there is a strong upper limit on speed
> regardless of the engine
> that you're using.
The fact that light from nearby stars is not
noticeably
blocked by interstellar junk sets a limit on how much
of
it there is. At significant speeds, loose hydrogen
atoms
start looking like a particle beam aimed at you, and
there
are _some_ interstellar dust grains. So you will need
a
leading edge shield on your spacecraft to protect you
from that stuff. But that doesn't limit you to speeds
that solve the Fermi Paradox.
Stars themselves move around. Among the nearest stars
are
ones moving relative to the Sun at over 100 km/s. So
simply
by moving arbitrarily slowly to such stars, then
riding
with that star for a while, and spreading to other
stars
when you pass by, you can fill the Galaxy by
'diffusion'
in a time (~300M years) much shorter than the age of
the
Galaxy.
[note: I _am_ a rocket scientist]
More likely,
> there's the what's to gain? argument to explain the
> absence of robots. If
> nobody's willing to go, then why bother to send more
> than a photographer (if
> that). And photographers might well choose to be
> inconspicuous, so as not to
> disrupt the scenery that they were shooting.
There's information to gain. Once you have the
ability
to build replicating systems, you can send out one or
a few
probes, whose decendants can survey the whole Galaxy
for you.
If they are built with the ability to communicate with
each other, you get back the survey information
without
leaving home, and you also have built a communications
network that can connect any civilizations in the
Galaxy
with each other. Pretty big return on your intitial
investment in probes.
>
> I'm not sure that the Fermi Paradox needs to be
> answered, because there are so
> many potential reasons, and plausibly different
> races would encounter
> different reasons.
By trying to answer the Fermi Paradox, we will learn
about the Universe we live in and something about our
origin
and future. That's enough reason for me.
See work by Gerard O'Neill on why planets are not the
best places to live. A sphere has the _minimum_
useable
surface area for a given mass, and most of the mass is
locked up deep inside where it is hard to get to.
Daniel
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