Answer 1:
Maybe. Think about this. If, in our solar system,
life only ever existed on earth, then we might
think that with life on one planet out of nine,
and billions of solar systems like ours, the
galaxy would be teeming with "aliens". But if we
are the only sentient beings in the galaxy, then
of course we *must* live in a solar system with a
"live" planet, because we're here to ask your
question. So effectively, when we count "planets
with life" we shouldn't count the earth: if there
weren't life on it, I'd be sending this email in a
solar system where there *was* life. So then it
becomes very important to look for the beginnings
of life elsewhere in the solar system (Mars,
Europa, Titan). Because if there's fossilized
bacteria in that meteorite from Mars, then a
*second* planet had life (besides ours), and it
starts to look as though the existence of life
isn't so uncommon. So in a surprising way,
looking for ancient, extinct forms of life on the
moons of Jupiter can actually help us look for
aliens.
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Answer 3:
I do, because space is so big. On the other hand,
the stars are so far apart that it seems very
unlikely they'd be able to travel far enough to
meet us.
Question: why do we think it's so
hard to travel the long distances between the
stars (even for technologically advanced
aliens)?
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