Douglas Adams. Hitchhiker's guide to the galaxy (№ 38567)

It is known that there are infinitely many planets.
This is due to the simple reason that the space in which they can exist is also infinite. However, not all of these planets are inhabited. It follows that the number of habitable planets certainly. The quotient of any finite number by infinity tends to zero and does not rest, therefore, we can conclude that the average population of the planets of the Universe is zero. It follows that the population in the whole Universe is also zero, and therefore all the people who sometimes get on your way, are a product of your fevered imagination.