There is no evidence to suggest that life has evolved elsewhere in the universe. However, given the vast scale of the universe, and the fact that life has evolved at least once, it is hopeful that life exists elsewhere.
You can research the possibility of life in the universe by doing astrobiology:
My guess would be probably not… the universe is so huge that it seems likely to me that life of some sort would have evolved elsewhere (in fact there is some evidence for simple life having existed on Mars).
Blimey – that’s a tough question! I have no idea. I think we’re probably not, because the universe is so huge that there must be somewhere else that has the right conditions for life to exist – probably so far away that we’d never know about them.
The universe is SO vast, with hundreds of billions of galaxies, each with hundreds of billions of stars, then I would be very surprised if we were the ONLY intelligence species alive. However, they would probably be so far away that it would take millions of years for them to reach us. The nearest galaxy, Andromeda, would take 2.5 million years to get to if you were travelling at the speed of light, so I really don’t believe that any aliens have ever visited earth.
That said, the above is just a statistical argument, and I don’t really know what the chances that any given planet will develop intelligent life, so I have to keep some scepticism. Ultimately, I’m not sure. I can’t express myself better than Arthur C. Clarke: “Sometimes I think we’re alone in the universe, and sometimes I think we’re not. In either case the idea is quite staggering.”