the universe contains billions of galaxies, each containing countless sloar systems, each containing many planets. not only is it possible, it would be IMPOSSIBLE to deny life outside earth. you have an infinite amount of planets, at least one of which is going to have another kind of life in it. in the words of andy biersack- "maybe they won't look like little green men, maybe they'll look like me, and then me and the aliens will hang out" there's just no denying it.
The likelihood of some form of life living elsewhere in this vast universe is extremely high, as shown by the Drake Equation. Already, even with our relatively limited capabilities, we have discovered nearly 500 planets in the "Goldilocks" range.
Of course, we have also discovered evidence that there used to be water on Mars, which could indicate primitive life was once possible there too.