July 2, 2022

Scientists: “Quantum Hair” Could Solve Hawking’s Black Hole Paradox

Stephen Hawking’s black hole information paradox has baffled scientists for half a century and led some to question the fundamental laws of physics. Scientists now say they may have solved the infamous problem by showing that black holes have a property known as ‘quantum hair’.

If true, this would be a huge advance in theoretical physics.

Professor Xavier Calmette, from the University of Sussex, who led the work, said that after working on the mathematics behind the problem for a decade, his team had made rapid progress in the past year that gave them confidence that they had finally solved the problem.

“It was generally assumed within the scientific community that resolving this paradox would require a massive paradigm shift in physics, forcing a possible reformulation of either quantum mechanics or general relativity,” Calmette said. “What we found – and I think particularly exciting – is that this is not necessary.”

The Hawking paradox is summarized as follows: The rules of quantum physics state that information is preserved. black holes It poses a challenge to this law because once an object enters a black hole, it disappears forever – along with any information encoded in it. Hawking identified this paradox and for decades continued to confuse scholars.

There have been a myriad of proposed solutions, including the “firewall theory” in which information was supposed to burn before entering a black hole, the “fuzz ball theory” in which black holes were thought to have blurred boundaries, and various branches of string theory. But most of these proposals required rewriting the laws of quantum mechanics or Einstein’s theory of gravity, the two mainstays of modern physics.

Stephen Hawking
Stephen Hawking’s paradox has puzzled scientists for decades. Photography: Triton / Kobal / Shutterstock / Sky Documentary

By contrast, quantum poetry theory claims to resolve the paradox by bridging the gap between general relativity and quantum mechanics using a new mathematical formula.

The name is a nod to the opinion, based on classical physics, that black holes can be considered surprisingly simple objects, defined only by their mass and rotational speed. The prediction of featureless bald black holes has been called the “hairless theory” since the 1970s.

Calmette and his collaborators believe a black hole is more complex — or hairy. They suggest that when matter collapses into a black hole, it leaves a faint imprint in its gravitational field. This fingerprint is referred to as a “quantum hair,” and the authors say it will provide the mechanism by which information is preserved as a black hole collapses. Under this theory, two black holes with identical masses and radii, but with a different internal configuration, would have very subtle differences in their gravitational fields.

“Our solution requires no speculative idea; instead, our research demonstrates that the two theories can be used to make consistent calculations of black holes and explain how to store information without the need for radical new physics.”

There is no obvious way to test the theory with astronomical observations – gravitational fluctuations would be too small to measure. But the theory is likely to come under intense scrutiny from the theoretical community.

Professor Toby Wiseman, a theoretical physicist at Imperial College London, called the paper “good work”, but remained unconvinced that it resolved the decades-old paradox.

Crucially, he said, the paper suggested it might be possible to glean some additional information about what was inside the black hole — but it didn’t show that this phenomenon could explain all the seemingly missing information. “They didn’t show up and that’s the crux of the contradiction,” he said.

“My feeling is that to really resolve this paradox, you have to fully understand how quantum mechanics and gravity combine,” he said. “They’re looking at small corrections, but not the whole mix of the two.”

Calmette said, “When you have a big claim, you have to support it. It will take some time for people to fully accept this. The irony has been around for a long time and you have very famous people all over the world working on this for years.”

The work was published in Physical Review Letters.