What are black holes? Mainstream physics sees them as Universe’s ultimate agents of death; afterall, what crosses over beyond the rim of the black hole – or its event horizon as it is known – disappears forever. Even all pervasive light cannot escape it. Science also shows that the universe is littered with billions upon billions of enormous black holes, capable of swallowing entire galaxies. But are they really the Universe’s cosmic executioners? Not necessarily, suggests Carlo Rovelli, one of the world’s leading theoretical physicists and prolific author of extremely accessible and thoughtful popular-books on modern physics. In his latest book, ‘White Holes', Professor Rovelli, discusses, well, so called ‘white holes.’ They may be the yin to the black holes’s yang, or as Rovelli describes it in Tolkienisque terms --the transformation of ‘Gandalf the Grey to Gandalf the White.’ In this podcast, we also talk about the role of scientific speculation, how scientific progress requires abandoning comforting assumptions, how new universes may be born, and whether we need to re-evaluate our commonly held notions of past and future.