Re:well. (Score 1)

Asimov has a book on this. I think it is called "Is There Life On Other Planets?". He did some mathematics to show that even if there are millions of other civilizations in the universe the probability of any two meeting is very small. There is little chance that other civilizations have come across the earth in the last 30000 years. even if they did there would probably be no reason for them to assume that there was intelligent life here.