I've once read an insteresting theory on alien life, I'll try to summarize it:
It is all based on the concept of infinity, and that
Inf. * Inf. = Inf.
step 1: It is generally believed that the universe is infinite
step 2: Even if the chance of alien life is minimal, this would mean there is a nearly 100% chance that it IS out there
step 3: As infinity is
infinite, that would mean there is an infinite number of alien life forms out there.
step 4: It is a scientific fact that the number of possible DNA combinations is not infinite.
step 5: assumed alien life is based on DNA as well, there is a nearly 100% possibility that at some point out there, there is one life form that has exactly the same genetical structure as every one of us.
step 6: Further applying the concept of infinity we can assume there the number of life forms with exactly the same DNA code as me or you, it is nearly certain that there is an endless number of copies of every one of us out there.
step 7: Imagine an infinite number of Puddings!
Dont know what to think of it, but I kept it in mind for years as I though this was an interesting idea