Session 2, 10 a.m.:

Abstract: Extraterrestrial life has yet to be found, but aliens have been lurking in the human mind for millennia. The idea that other worlds may harbor inhabitants of their own goes back to antiquity. Renaissance philosophers debated it. 19^th-century science suggested an inhabited Mars. Science fiction and the Space Age contributed new speculations and new data. The long “plurality of worlds” conversation is still going on.