A Nobel Prize for Stephen Hawking who could have been

Did death cheat Stephen Hawking for a Nobel Prize?

When the iconic physicist passed away on March 14, 2018, data was already available that could confirm a disturbing and far-reaching prediction he had made more than four decades earlier. Dr Hawking had postulated that black holes, those mouths of gravitational doom, could only grow, never smaller – swallowing information as it went and thus threatening our ability to trace the history of the universe.

This data was obtained in 2015 when the Laser Interferometer Gravitational-Wave Observatory, or LIGO, recorded signals from two massive black holes that collided and created an even more massive black hole.

Dr. Hawking’s prediction was a crucial first step in a slew of black hole information that has transformed modern physics. The stake is to know if the Einsteinian gravity, which shapes the larger universe, respects the same rules as quantum mechanics, the paradoxical rules which prevail inside the atom.

Confirmation of Dr. Hawking’s prediction was published this summer in Physical Review Letters. A team led by Maximiliano Isi, a physicist at the Massachusetts Institute of Technology, and his colleagues had spent years digging into the details of LIGO’s findings, and in July they finally announced that Dr Hawking was right, at least for that. particular black. collision of holes.

“This is an exciting test because it is a long desired result that cannot be achieved in a laboratory on Earth,” said Matthew Giesler, Cornell University researcher and member of Dr Isi’s team, in an email. “This test required studying the merger of two black holes over a billion light years away and simply could not be done without LIGO and its unprecedented detectors.”

No one claims to know the spirit of the Nobel Prize committee, and the names of those nominated for the prize are withheld for another 50 years. But many scientists agree that Dr Isi’s confirmation of Dr Hawking’s prediction could have made Dr Hawking – and his co-authors of a definitive paper on it – eligible for a Nobel Prize.

But the Nobel Prize cannot be awarded posthumously. Dr. Isi’s result came too late.

Nobel Prize week returned on Monday, when some scientists hope for a phone call anointing them as laureates and summoning them to a lavish ceremony in Stockholm on December 10. (This year, due to the pandemic, the awards will be presented in the winners’ home countries.)

Dr Hawking, arguably one of the most famous and honored researchers, has never won a Nobel Prize and never will. Its story is a reminder of how the Ultimate Prestige Prize is subject to the inconstancy of fate.

The stupefaction of the universe

The story begins in 1970, when Dr Hawking was getting ready for bed one night – a daunting task for a man already half paralyzed with amyotrophic lateral sclerosis, or Lou Gehrig’s disease.

According to Albert Einstein’s theory of general relativity, he had thought of black holes – objects whose gravity is so strong that even light cannot escape them. They are endless windows.

Each black hole is surrounded by an event horizon, an invisible bubble marking the frontier of no return; whatever comes in will never come out. Dr. Hawking realized that Einstein’s theory also meant that a black hole’s event horizon could never shrink. A black hole only gains mass, so the total area of ​​its event horizon only grows.

It was a bold idea. Nature didn’t have to work that way. What if black holes could split in half, or splash and disappear, like soap bubbles?

Dr. Hawking’s insight became the keystone of a 1973 article, “The Four Laws of Black Hole Mechanics,” he wrote with James Bardeen, now at the University of Washington, and Brandon Carter. , now at the French National Center for Scientific Research.

These laws also contained a troubling conclusion to physics called the “hairless” theorem. The area of ​​an event horizon is a measure of all the information swallowed by a black hole. It is the same for a black hole that it consumes matter or antimatter, a Tesla or a Volkswagen, an ostrich or a whale. Black holes have only three properties: mass, spin, and electric charge. No other detail, or “hair,” is recorded.

This theorem meant that as a black hole ages and its event horizon widens, the amount of information lost about what it contains would also increase. The universe would become more and more dumber, hiding more and more details of its past, possibly including your existence. The riddle deepened in 1974 when Dr. Hawking calculated that quantum effects would cause a black hole to slowly leak and explode.

The quest to understand what happens to information in a black hole has transformed fundamental physics and energized a generation of young theorists. The stake is to know if the Einsteinian gravity, which governs the cosmos, and quantum mechanics, which governs the microcosm, play by the same rules.

“It all started with Hawking’s realization that the total horizon area of ​​black holes can never decrease,” Dr. Isi said.

But without black holes to experiment with, Dr. Hawking’s ideas could not be tested.

LIGO to the rescue

LIGO would change that. This is the promise that Kip Thorne, a theoretical physicist at the California Institute of Technology and one of the founders of LIGO, made to Dr. Hawking in 2003. The new network would be able to sort out the properties of black holes by the time Dr. Hawking turned 70 in 2012.

“Your giveaway is that our gravitational wave detectors – LIGO, GEO, Virgo and LISA – will test your Golden Age black hole predictions, and they will start to do so well before your 70th birthday,” said recently remembered Dr. Thorne for telling him.

It took longer than that – until September 14, 2015 – for LIGO to observe its first epoch event: two colliding black holes. By matching the detected wave patterns with computer simulations, the LIGO team concluded that one of the black holes was 36 times as massive as our sun and the other was 29 times as massive, which is equivalent to to 65 suns in total. The collision gave rise to a new black hole with a mass of about 62 suns. Three suns of energy had disappeared in the gravitational waves that rocked the universe.

The observation not only confirmed the existence of gravitational waves, as Einstein predicted 100 years earlier, but provided the first direct evidence of black holes.

A leaked copy of the discovery document reached Dr Hawking days before the official announcement of the results. He was surprised to find no mention of the four laws of black hole mechanics, or the possibility that the discovery could test them. He contacted Dr Thorne, author of the article.

“Steven is quite surprised,” Dr. Thorne wrote to his colleagues.

No one had thought to check the laws of black hole mechanics, and it was too late to add anything to the document. Plus, as Dr Thorne explained recently, the data was too noisy to measure the size of the newly formed black hole well enough to confirm Dr Hawking’s theory.

In 2017, then-graduate student Dr. Giesler at Caltech and his colleagues used digital simulations of black hole collisions to take a deeper look at the doomsday vortex.

When a newly merged black hole forms, it vibrates. Like a drum, it generates fundamental tonality as well as overtones – overtones or undertones. The harmonics were found to be surprisingly strong early in the merging process, Dr. Giesler found. Using these harmonics, in 2019, he and his colleagues proved the “hairless” theorem, which states that black holes can only be described by three parameters.

This summer, they were able to extend their analysis by exploiting a harmonic of the new black hole to measure its size. They concluded that the area of ​​the event horizon of the new black hole had increased, as Dr. Hawking had predicted so long ago.

Nobel dreams

Would that have won Dr. Hawking the Nobel Prize if he was still alive?

“I don’t feel comfortable speculating,” said Dr Thorne, who in 2017 shared the Nobel Prize in Physics for his role in the development of LIGO.

Andrew Strominger of Harvard, a longtime collaborator of Dr Hawking, said: “I am not aware of the deliberations of the Nobel Committee, but Hawking could have already been included in this prize if he was still alive. These more recent experiences would certainly make the case even more solid. “

Daniel Holz, an astrophysicist at the University of Chicago who is part of the LIGO collaboration but not part of Dr Isi’s team, called the result “crazy cool.”

“This is undoubtedly a confirmation of observation of one of his predictions,” he said. “I hope the Nobel committee realizes that.”

The physics prize has always focused on practical and experimental discoveries; even Einstein won the award for explaining the photoelectric effect, not for relativity. The furthest that the Nobel committee has gone into theoretical astrophysics lately was in 2020, when Roger Penrose of the University of Oxford received the prize for proving that black holes are possible in the universe.

But he shared the prize with two astronomers, Reinhard Genzel, of the Max Planck Institute for Alien Physics, and Andrea Ghez, of the University of California, Los Angeles, both of whom had studied the supermassive black hole at the center of the Milky Way.

Even if Dr. Hawking was still alive when his black hole area theorem was proven, it would have been difficult to fit in – a Nobel Prize can be awarded to up to three people. And what about Dr. Bardeen and Dr. Carter, the co-authors of Dr. Hawking? What about Dr Isi’s team?

Dr Hawking wouldn’t be the first scientist to die too soon for a possible Nobel Prize.

“I was told that the Nobel Committee regretted not awarding a prize to Hubble,” wrote Michael Turner, a prominent cosmologist now working for the Kavli Foundation in Los Angeles, in an email, referring to the astronomer Edwin Hubble, who discovered the expansion. of the universe. “But he died first.”

Robert Brout, theoretical physicist at the Université Libre de Bruxelles, would probably have been included in the 2013 Nobel Prize for predicting the existence of the Higgs boson, along with his colleague François Englert and Peter Higgs from the University of Edinburgh, s ‘he had not died in 2011.

Ronald Drever of the University of Glasgow, one of the founders of LIGO, could very well have shared the 2017 Nobel Prize with Dr Thorne and Rainer Weiss of MIT had he not passed away in early 2017. His place was occupied by Barry C. Barish of Caltech.

Dr Hawking rests next to Isaac Newton and Charles Darwin in Westminster Abbey. It might be better than spending a winter in Stockholm.