For decades we've been told there's something out there. Jim Al-Khalili, host of Radio 4's The Life Scientific and an inaugural winner of the Stephen Hawking Medal for Science Communication, has been gathering the latest word from within the science community about those little green folks (if that's what they'll look like) and their potential existence. In this event recorded live at the 2017 Edinburgh International Book Festival, Al-Khalili shares his new book, Aliens.