h2g2 The Hitchhiker's Guide to the Galaxy: Earth Edition

Well, there so far hasn't been proven anything either way. But I do think we have gotten some indications, that might say something.

1) We have found traces of the amino acids that are the "building blocks" of life in meteors.

2) There are in the nebulas huge quantities of water vapors and carbon, which are both important for life as we know it.

3) It seems here on Earth that life originated quite quickly, after Earth had cooled down and gotten a liquid surface.

4) It has been shown that (I don=t know too much about this) the ice in the nebulas, can start to spontanously turn into more complex molecules when the infrared rays of the sun hit it.

5) We have seen here on Earth how life can live in very extreme circumstances.

All in all, I'd say the case for alien life looks quite good. The evidence is just only indications, nothing defininite. The problems that arises are then that we may have seen life can live in harsh enviroments, but not necessarily that it can originate there. And life did originate on Earth quite quickly, but it took a very long time before we saw multicellular life. So perhaps life is spread out all across the universe, it is just only in a few situations that it ever came over the bacterial stage. Probably the situation on Mars, but that's just my opinion.

The fact that we are here indicates that life is possible elsewhere.
We do not know if it has evolved to the same stage or if it is more advanced but one way or another we should find out.

All i have to say is that there are too many galaxys out there to assume that there are NOT any other life forms. I agree, proof would be nice and would despel any doubts about it but i think its only to obvious to asume that we are "not alone."

I agree that it's practically certain that 'they' are out there somewhere.

However, if we take even the more advanced, more communicative civilizations, assuming they are scattered in random galaxies (for the sake of argument, not our own galaxy), and assuming they are bound by the same physical laws, how would we get proof (or any evidence) of their existence?

In other words, what kind of signal would be needed for us to be reasonably sure alien life existed in another galaxy, selected at random from all those within our light-cone?

Higgsy, AKA Djob

Hn...interesting idea, and scary too if you think about it! Brings up scenes from all those alien encounter movies like Independence Day and whatnot. One would like to think that some of the 'aliens' are nice, imagine what technological advances we would have if we hooked up with another race hmm?