The notion of aliens from other planets often conjures images of flying saucers and little green men. But could they really exist?

Even though the belief in alien life forms is typically derided as wild or delusional, scientists and other serious thinkers have long grappled with both their theoretical possibility and myriad sightings that remain mysterious.

Among the guests in this episode is Paul Davies, theoretical physicist, cosmologist, best-selling author and director of ASU’s Beyond Center for Fundamental Concepts in Science.