I believe in aliens, do you?
Sure.  The universe is a big place. I mean, they might not be an advanced civilization like us, maybe just simple prokaryotes 
I agree with you, the universe is too big for only us to exist as Earth makes up such a tiny portion of it as a whole. There has to be more life out there.
There's something called the Drake equation that tries to calculate the odds of other life in the universe, but I don't remember all the values.
Oh wow, really? I had not heard of that. There are all sorts of theories out there in favor and against the idea of extraterrestrial life. It can be a very controversial topic.
It's almost a paradox.  Like the Drake equation calculates a lot of other civilizations, yet there is no evidence of the existence of any.
That sure is interesting, I'm going to have to research more into that.
Read into something called the Fermi Paradox.  It deals with the question of where is everybody else out there?