White Holes: Inside the Horizon review – Carlo Rovelli turns time on its head

‘Having started with a black hole, an object into which you could only fall, Rovelli conjures a white hole, from which things can only pour.’ Photograph: Elen11/Getty Images/iStockphoto

I read Stephen Hawking’s A Brief History of Time more than 30 years ago. It woke me up to the wonders of the universe in a way that nothing before ever had. And while I’m not sure I fully understood it then, or now, it certainly felt like an adventure. Carlo Rovelli’s new book is a kind of non-linear sequel in which he introduces his theory of “white holes”, how they might form and why we have such trouble seeing them in the universe today.

Black holes form from stars so massive that when they reach the end of their lives and all their fuel is spent, they collapse to form bizarre objects from which nothing can escape, not even light itself. Albert Einstein’s theory of general relativity predicted their existence: entities within which space and time had to come to an end.