If you thought aliens were just a figment of someone's overactive imagination, think again. Host Dallas Campbell meets the man who made the search for extraterrestrial life respectable: Professor Frank Drake. Using the mathematics of probability, Drake has shown that we might have more alien neighbors than we thought. And now, scientists are trying to track them down.

If you thought aliens were just a figment of someone's overactive imagination, think again. Host Dallas Campbell meets the man who made the search for extraterrestrial life respectable: Professor Frank Drake. Using the mathematics of probability, Drake has shown that we might have more alien neighbors than we thought. And now, scientists are trying to track them down.