Hawking’s paradox still puzzles physicists

Physicist Stephen Hawking died six years ago, on 14 March 2018. Fifty years ago, he published a Nature paper with the enigmatic title: Black hole explosions? The paper introduced the concept of ‘Hawking radiation’: the idea that black holes are not truly black because they constantly emit a tiny amount of heat. As Hawking soon realised, this creates a paradox. Hawking radiation doesn’t maintain the details of the original material that went into the hole; therefore, it inexorably erases information from the Universe, contradicting the laws of quantum mechanics. Efforts to solve the conundrum have led to legendary wagers, a theory that wormholes connect the inside of black holes with the outside and the idea that the Universe is a hologram.