FEW topics in physics so capture the imagination as black holes. They are the sites of wholesale gravitational collapse: stellar remnants fold in on themselves, reaching a density so extreme that it pokes an incomprehensible little hole in the fabric of space itself. The resulting gravitational pull is so great, the story goes, that anything that crosses a point of no return—the event horizon—is lost, in its entirety, forever. But even that simple formulation comes with a wrinkle that has had theorists pulling their hair out for four decades. This week Stephen Hawking, a physicist known for his work on the astronomical phenomenon, put forward a possible solution to the paradox. But what is the kerfuffle all about?
