About other life in the cosmos:
The chances must be high, and is suggested by the things we've come to understand about our own form of life.
1) We are made, principally, of the most common elements in the universe (Hydrogen, Oxygen, Carbon, etc)
2) Carbon is the most chemically active element. (it has been said that carbon can form more molecules than the rest of the periodic table combined)
3) The laws of physics are the same everywhere.
4) It didn't take long for life to begin on Earth. (only 200 million years after it cooled sufficiently after formation, which is a tiny space of time in cosmological terms), and
5) The universe is very big (as already pointed out, 100 billion galaxies containing 100 billion stars each.)
Some stars have planets, and some of those planets are bound by the laws of probability to be chemically similar to our planet.
When you add these up, the probability of our life being the ONLY life in the universe, or even our own galaxy, are slim. And that just the kind of life we know about! Who knows what life may be made of elsewhere?
However, our chances of finding ET (or ET finding us) are also ludicrously slim, because:
1) The universe is very big, and
2) The fastest anything can go is the speed of light. We might detect a radio signal from a distant civilisation (or a distant civilisation might accidentally catch an episode of
I Love Lucy), but there almost bound to be too far away to establish effective communications. (For example, if ETs planet was in the center of the galaxy, it would take around 60 000 years to get a response from them). And then (assuming we can't create, and travel through, wormholes, which is a safe assumption), the distance is bound to be much too far for our respective civilisations to be visiting each other for lunch.
Niel deGrasse Tyson, a cosmologist and populariser of science, says this kind of stuff on the lecture circuit. He's fun to listen too, and he's all over youtube.
eg
http://www.youtube.com/watch?v=Re66MWWl8q8&feature=related