Many scientists think it is possible that there is life elsewhere in the Universe, but that finding it may prove difficult.
First of all, we don't know exactly what form life on other planets outside our solar system might take, so it is difficult to know how to search for it. Second, the universe is a big place, and radio signals (and space vehicles) travel too slowly to allow us to find life that is very far away.
We do know something about the conditions on Mars, the planet in our solar system which is most likely to have life, and it turns out to be similar to the conditions in Antarctica (except for the lack of oxygen).
So we can guess what forms of life might be able to survive there, and there are projects under way that will someday send machines to Mars which can look for these kinds of life. There is more information about the exploration of Mars, for example in: