Well, science hasn't found them yet, but I do think they exist. Not the crazy green aliens with big eyes we see in movies, but life on other planets. Yes. Just think about this for a minute. We haven't even been outside of our galaxy yet. And there are hundreds of billions of galaxies in our universe. We can't be the ONLY planet with some form of life.
maybe because our universe is so so so so so so so........ FREAKING HUGE that it might contain life at any distant corner of any one of billiion or i may say zillionth galaxy.... SO ITS HARD TO SAY WHETHER THEY EXIST OR NOT :)
There is a theory that life on Earth began from protein strands that came from meteors... making us the aliens to this planet :P
Anyway, a guy named Frank Drake tried to come up with a mathematical model showing the possibility of life existing elsewhere in the universe that was evolved enough to communicate. The formula includes things like - a planet being the same distance from the Sun as we are (not to close to burn up and not too far and freeze), presence of water, etc, etc. The formula has been updated quite a bit since he came up with it in the 60's, but apparently the math nerds say there are potentially more than 1000 civilizations in our Milky Way galaxy alone (out of 200-400 BILLION planets).
The bigger question would be.... what are the odds of communicating in our lifetime? Space is a pretty big place.....
People who ask these questions are just trying to start arguments. Haven't you read answers to questions similar to this one? They all say no. The only thing remotely close to life on other planets are dried up riverbeds on the planets closer to the sun and ice on planets farther from the sun.