Stephen Hawking, who once stunned the scientific community by saying that black holes emit radiation, expounded on another groundbreaking theory on Tuesday.

"The message of this lecture is that black holes ain't as black as they are painted. They are not the eternal prisons they were once thought," Hawking told a meeting of experts, according to the New Scientist. "Things can get out of a black hole both on the outside and possibly come out in another universe."

This, of course, is not what you learned in physics class. What you learned is that once anything made it past a black hole's event horizon, the black hole's super strong gravitational force would suck it in forever. Any information particle sucked in by the hole would also disappear for good.

As The Wall Street Journal explains it, this is also where one of physics' big, unanswered questions — something called the "information paradox" — comes in:

"Quantum mechanics—a highly successful theory that describes physical phenomena at the scale of atoms and subatomic particles—says that information can never be lost, even when it falls into a black hole. It is widely believed to be an inviolable law of nature.

"How to get around this so-called information paradox? Some physicists suggested that perhaps information did somehow escape a black hole. Prof. Hawking vociferously maintained that this could never happen. Then, some three decades later, he presented calculations that showed how information could leak out of a black hole, after all. The challenge has been to figure out how that might happen."

During his talk on Tuesday at the KTH Royal Institute of Technology in Stockholm, Hawking proposed that the information of the particles sucked into a black hole eventually makes it out in the radiation that is emitted by a black hole.

The information emitted, however, is not usable.

The Washington Post reports:

"At Monday's public lecture, he explained this jumbled return of information was like burning an encyclopedia: You wouldn't technically lose any information if you kept all of the ashes in one place, but you'd have a hard time looking up the capital of Minnesota."

The Journal notes that Gerard 't Hooft of Utrecht University, winner of the 1999 Nobel Prize in physics who was present at the conference, had presented a similar idea in 1996.

He said the problem was that his math did not add up.

"I claim he is now where I was 20 years ago," he told the Journal. "If he announces this as a new idea, I won't be thrilled."

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