I'm sure the universe is full of intelligent life. It's just been too intelligent to come here.

Two possibilities exist: either we are alone in the Universe or we are not. Both are equally terrifying.

Perhaps, as some wit remarked, the best proof that there is Intelligent Life in Outer Space is the fact it hasn't come here. Well, it can't hide forever - one day we will overhear it.

Just like the cosmonauts and their pee plants, all we have is each other.

Sometimes I think we're alone in the universe, and sometimes I think we're not. In either case the idea is quite staggering.

…only in the few universes that are like ours would intelligent beings develop and ask the question: “Why is the universe the way we see it?” The answer is then simple: If it had been any different, we would not be here!