You're too modest; the Milky Way alone has a projected 200 to 400 billion stars. And there are estimated to be 100 billion galaxies in the observable universe. Now, for simplicity's sake we'll say all galaxies have the same number of stars as the Milky Way; that's anywhere from 2 X 10^22 to 4 X 10^22 stars in the known universe. All of those stars have the probability of having orbiting planets, with perhaps one or two providing conditions to sustain life.

Multi-cellular life requires more precise conditions to survive than, say, extremophiles. Thus to have carbon-based life as we know it would require conditions similar to earth's. This would be much rarer than planets with barely enough hospitable conditions for extremophiles, however when you take into account the vastness of the universe and the quadrillions and quadrillions of stars and planets out there, there are very likely planets that either harbor carbon-based life or will in the future gain the environmental conditions to provide for carbon-based life, if they are on the fringe of, say, harboring liquid water (though many other criteria must be met to replicate the conditions found on earth).

Intelligent life, as we know it, is probably extremely rare in the universe, but it is also quite possible, given the multitude of planets and probability for suitable conditions. So, in response to the topic, yes. Extra-terrestrial life is possible.

Agreed. The probability of out planet being able to support life is so amazingly small, that there must be another somewhere out there that falls within the same window of probability. Whether or not we will ever meet another intelligent life form is pretty slim, but finding some kind of life that did not originate on this planet, no matter what level, I think, is pretty good.

If that's what you truly believe, then you voted the wrong way.

What leads you to say it's not likely?

The milky way alone has somewhere between 200 and 400 billion stars. It's likely that many of these stars have planets, but it's what the ratio of planets to stars is; to be on the safe side, lets say there's one planet for every hundred stars. That gives us about 3 billion planets.

Life on earth evolved to very specific conditions. Early life forms on earth likely evolved in water, with certain atoms--carbon, hydrogen, oxygen, and nitrogen--present, and with access to mild sunlight, 1 atm of pressure, and countless other conditions. It's likely that life could form in different conditions, and perhaps very different conditions, but to be on the conservative side, let's assume that it can't. Lets say only one in, say, a hundred million planets are earth-like. That gives us 30 hospitable planets in our galaxy.

The likelihood of life forming on a livable planet is a total crap-shoot. It could be all but inevitable, or it could be a one-in-a-trillion. Again, lets be conservative and say that it's incredibly unlikely. That gives us a 0.00000000003 chance of life forming in any one galaxy.

The thing is, though, there are an almost infinite number of galaxies. Saying that there are more galaxies then there are grains of sand in all the world's beaches is a gross understatement. Saying that there are more galaxies than there are atoms in the earth is a bit closer, but not much.

If there's a virtually infinite number of galaxies, the odds of there being life on other planets--even if the odds are terrible for any one planet, or any one galaxy--are incredibly high, to to point where the evolution of life on many, many other planets is all but a statistical certainty. The only exception would be if there was something special about Earth that no (or almost no) other planets shared, but there's no reason to assume this is the case. The more we learn about astronomy, the more we learn how un-special our planet and solar system are. If life arose naturally, extra-terrestrial life isn't just possible, it's all but certain.