I once did a "Back of an envelope" calculation on the possibility of life other than us somewhere in the Universe and came up with a big fat no. In fact, it's extremely lucky that we happened along. A lot of things have to happen just right for life to exist. You've got to have a spinning planet with a large iron core so as to create a magnetic field to protect us from solar radiation for starters. That means you have to have been struck by a particularly large body that will add it's iron to yours and impart just the right spin while throwing off a moon of the right size for tides to form. Then you have to have water, and this can take quite a while. Oh yeah, your planet has to have time to cool off and settle down. Then, you need a miraculous collision from an asteroid that kills of all of your giant meat eating reptiles. This list goes on and on until by my calculation we don't exist nor does any other life form. Somewhere a miracle occurs.
I completely disagree with this. There IS life out there. It's just a matter of time before we prove it. I think it's likely that life in some form existed on Mars in the distant past. Scientists have already found dozens of planets that exist in the "goldilocks zone" of other solar systems. I'm not sure about UFO's. They are unlikely, but I can't dismiss the possibility.
