It is known that there is an infinite number of worlds, but that not every one is inhabited.  Therefore, there must be a finite number of inhabited worlds.  Any finite number divided by infinity is as near to nothing as makes no odds, so if every planet in the Universe has a population of zero then the entire population of the Universe must also be zero, and any people you may actually meet from time to time are merely the products of a deranged imagination.  ~Douglas Adams, The Original Hitchhiker Radio ScriptFit the Fifth, p102; HM