That is a rather arrogant position to take and more of a belief than a fact. Someday, I am sure humanity will know for certain whether we are alone in the universe.The short answer is, the statistically impossible chain of events that would be required to form life, even if you used every atom in the universe and had them recombine a trillion times a second, would require trillions of years to accidentally come up with the right combination for life. Using only those elements and atoms available on a planet, would require infinitely longer. It is an impossibility. The fact there is life on earth is the result of intelligent design, not random recombinations of atoms. The bottom line is, there is no life, much less intelligent life, anywhere in the entire universe, other than earth. Sometimes I wonder if there is actually intelligent life on Earth.