http://www.kqed.org/.stream/anon/radio/quest/2011/05/2011-05-09-quest.mp3
Of all the questions in science, few have haunted humans as persistently as this: Are we alone? For more than 50 years, scientists have listened for a signal from intelligent life on other planets... and come up empty. Now, they're running short of money. Is it time to give up?