Marcus Chown is an award-winning writer, broadcaster and former radio astronomer at the California Institute of Technology in Pasadena. He's the author of The Ascent of Gravity, Quantum Theory Cannot Hurt you and Afterglow of Creation.

His latest title, A Crack in Everything: How Black Holes Came in from the Cold and Took Cosmic Centre Stage details the mind-blowing science of black holes, and traces this, once preposterous idea to its obscure beginnings.

In this interstellar conversation we discuss what would have happened if you managed to fall into a black hole, whether time travel is indeed possible, why black holes aren't really black and finally, why do we find them at the centre of every galaxy in space.