Stephen Hawking might have just lost himself a bet. Again.
The famed physicist has written in a new paper that "there are no black holes" - despite being one of the minds behind modern black hole theory.
Hawking writes in his paper that the notion of an event horizon - a gravitational boundary beyond which no information about a black hole, or even light, can escape - doesn't actually exist.
Instead he writes that a black hole is instead marked by an "apparent horizon" - from which matter and energy can escape, though in a confused form compared to when they entered.
The paper is an attempt to solve a paradox created in 1976 - by himself. In his early work, Hawking calculated that a black hole does radiate energy, but in order to not contradict general relativity that the energy must hold no information about the black hole.
But that idea was contradicted by the laws of quantum physics, which say information cannot be completely lost. So either Hawking was wrong, or quantum physics needed to be rewritten.
Regardless, Hawking was sure that he was right. He even made a bet in 1997 with the physicist Kip Thorne of CalTech, to the effect that if he conceded he was wrong, he would give Thorne an encyclopaedia of his choice.
It was 2004 when Hawking first admitted he had probably been on the wrong side all along. He even sent Thorne the book - an encyclopaedia of Baseball. But the physics community did not widely accept his explanation of the paradox - and the problem remains.
Hawking's new paper is a new proposal to solve the problem. It has not yet passed peer review, and as such cannot be taken as more than a hint towards a solution. And Hawking admits that a full explanation would still require a resolution between quantum physics and relativity.
But he maintains that his new work might be a glimpse at a resolution.
Specifically, Hawking argues that the quantum physics around a black hole is so intense, it causes space-time to fluctuate too much for a boundary to be created. Instead of matter being pulled right to the core of a black hole, it would instead gradually move inward but radiate energy, which though very scrambled could be theoretically reordered into a useful form.
"The absence of event horizons means that there are no black holes — in the sense of regimes from which light can't escape to infinity," he says.
In truth, the science behind the idea is complex, and we recommend reading Nature's write-up on the paper to fully appreciate some of the ideas involved.
But it's still an intriguing development - and an inspiring one. Even at 72, Hawking is still contributing new and useful ideas to the field that in the public eye he has dominated for more than 40 years, despite his devastating illness.