Overview: We look up at the night sky and see millions of stars and galaxies, but is there anyone looking back? Fifty years ago, astronomer Professor Frank Drake took a handful of guesses and turned them into proper science. Bang Goes the Theory's Dallas Campbell meets the man who made the search for aliens respectable. Drake used probability to estimate the number of intelligent civilizations there might be in the galaxy. His conservative figures suggest that there are up to one hundred million planets with intelligent life in our galaxy alone. Drake's search became formalized into SETI, the Search for Extraterrestrial Intelligence in Northern California. Scientists hunt for alien intelligence through radio waves, hoping to find a radio footprint or perhaps a beacon announcing themselves to the whole universe. Yet 50 years later, where is everybody?