Stephen Hawking’s Final Paper on Hairy Black Holes Published Online

Stephen Hawking’s final scientific paper has been published online. It can be read here.

The paper is titled "Black Hole Entropy and Soft Hair." In a foreword to the paper, Hawking’s co-authors Sasha Haco,  Malcolm J. Perry and Andrew Strominger said: “We are deeply saddened to lose our much-loved friend and collaborator Stephen Hawking, whose contributions to black hole physics remained vitally stimulating to the very end.

“This paper summarizes the status of our long-term project on large diffeomorphisms, soft hair and the quantum structure of black holes until the end of our time together.”

The study is incredibly complex. It deals with the idea that some information could survive being pulled into a black hole.

729665main_A-BlackHoleArt-pia16695_full Artist's concept of a supermassive black hole. NASA

Generally, it is thought nothing, not even light, can escape a black hole. All matter that reached the event horizon—the point of no return—would be sucked in leaving no trace behind. But Hawking and his colleagues refute this idea. They say information could be preserved at the “soft hairs” that hypothetically exist at the edge of a black hole.

Presenting his research on black holes and soft hair in 2015, Hawking said: “I propose that the information is stored not in the interior of the black hole as one might expect, but on its boundary, the event horizon... The idea is the super translations are a hologram of the ingoing particles. Thus they contain all the information that would otherwise be lost ... The information about ingoing particles is returned, but in a chaotic and useless form. This resolves the information paradox. For all practical purposes, the information is lost."

At the same conference, Hawking also said objects that fall into black holes could end up in another universe. "The existence of alternative histories with black holes suggests this might be possible. The hole would need to be large and if it was rotating it might have a passage to another universe. But you couldn't come back to our universe.

"The message is ... black holes ain't as black as they are painted. They are not the eternal prisons they were once thought. Things can get out of a black hole both on the outside and possibly come out in another universe."

Hawking died in March at the age of 76.

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