Light Holograms Preserve Black Hole Information, According to Stephen Hawking

January 12, 2016 | Joanne Kennell

Artist’s impression of a supermassive black hole at the centre of a galaxy
Photo credit: ESO/L. Calçada (CC BY 4.0)

They act like hard drives to store information.

Black holes are extremely interesting and there is still a lot unknown about them, however, British theoretical physicist Stephen Hawking may have discovered a way to solve the black hole information paradox.  How?  By holographic imprint.

Hawking hinted to a new theory back in August 2015, and he finally posted his paper online at arXiv.org on January 5.  In his paper, he states that black hole ‘hairs’ that form on the event horizon make a two-dimensional holographic imprint of anything that is sucked in.

Let’s try to figure this out.

First of all, what is the black hole information paradox?  According to Einstein’s general theory of relativity, all information that crosses the boundary of a black hole — called the event horizon — is lost forever, including light.  However, in the 1970’s, Hawking used the idea of quantum mechanics to propose that the universe is filled with particles that come in and out of existence and destroy each other as soon as they come in contact, except if they happen on either side of a black hole’s event horizon — meaning one particle gets consumed while the other radiates away into space.

So when a black hole disappears, according to Hawking, information is lost forever, which is a problem, because quantum mechanics states that information can never be lost. Voila, the paradox.

SEE ALSO: Magnetic Field From a Black Hole Detected for First Time

Now, what about this hair?  The theory goes that if black holes are bald, there will be no difference between any of them no matter what they consumed — they will all have the same mass, electric charge, and angular momentum.  However, if they have hair, there will be some sort of information about what a black hole has gobbled up.

Hawking has believed these hairs existed for years, and now he thinks they can solve the paradox.  “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,” Hawking said at a conference back in August 2015.

The paper states that Hawking and his colleagues, physicists Malcolm J. Perry from the University of Cambridge, and Andrew Strominger from Harvard University, have steps explaining how information can escape a black hole.  “We show that when a charged particle goes in, it adds a soft photon to the black hole. So it adds ‘hair' to the black hole,” Strominger told Seth Fletcher at Scientific American.

When charged particles enter a black hole, their information leaves a two-dimensional holographic imprint on the event horizon, and when light particles are ejected by a black hole — known as Hawking radiation — they can pick up the information from the event horizon and carry it with them into the Universe.  “The information about ingoing particles is returned, but in a chaotic and useless form," said Hawking. "This resolves the information paradox. For all practical purposes, the information is lost.”

Not everyone is convinced of the idea, and Perry even admitted that they are not sure this is the right answer to the black hole information paradox.  But at least now, other scientists can review their work and possibly bring forth further ideas to help verify or dismiss the theory.

Read more about Hawking's presentation in August: Stephen Hawking Proposes New Theory to Resolve Mystery of Black Holes

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