Stephen Hawking's Famous Scientific Bets

Stephen Hawking had a great fondness for scientific bets. They were partly fun, but also a serious habit of mind: a public, light-hearted way of staking out a clear position and then, crucially, conceding gracefully when the evidence turned against him. Here are his three most famous wagers.

The black hole bet, with Kip Thorne (1974)

In 1974 Hawking made a bet with his friend Kip Thorne about the object known as Cygnus X-1. Thorne bet that it was a black hole; Hawking bet that it was not, an odd position for the world's leading black hole theorist. Hawking explained it as a kind of insurance policy: he had devoted his career to black holes, so if it somehow turned out they did not exist, at least he would have the consolation of winning the bet. As the evidence that Cygnus X-1 contains a black hole became overwhelming, Hawking conceded in 1990. The stakes were characteristically jokey: a magazine subscription was on the line.

The information paradox bet, with John Preskill (1997)

A more serious wager concerned the black hole information paradox. In 1997 Hawking and Thorne bet the physicist John Preskill that information swallowed by a black hole is genuinely destroyed, violating a core principle of quantum mechanics. Preskill bet that the information must somehow survive. The agreed prize was an encyclopaedia, from which, fittingly, information can always be retrieved. In 2004 Hawking publicly conceded, announcing that he now believed information is preserved after all, and presented Preskill with a baseball encyclopaedia. It remains one of the most famous concessions in modern physics.

The Higgs boson bet, with Gordon Kane (early 2000s)

Hawking also bet the physicist Gordon Kane around one hundred dollars that the Higgs boson, the long-sought particle behind the origin of mass, would never be found. He lost. When CERN's Large Hadron Collider confirmed the Higgs in 2012, Hawking conceded with good grace, paid up, and generously remarked that Peter Higgs deserved a Nobel Prize for the prediction. Higgs duly received one in 2013.

Why the bets matter

Hawking's wagers were more than entertainment. Each forced him to commit to a clear, falsifiable position, and each ended with him changing his mind in public when the facts demanded it. That willingness to be proved wrong, cheerfully and openly, is one of the most admirable features of how he worked, explored further on the page about how his mind worked.