Stephen Hawking's last paper on black holes goes online

Stephen Hawking, a scientist who never stopped trying to discover the mysteries surrounding the black holes. In fact, he was still trying to solve one of them shortly before his demise. Now, thanks to his co-authors from Cambridge and Harvard, his last research paper is now available online.

Under the moniker Black Hole Entropy and Soft Hair, the paper explains the black hole paradox. According to Hawking's co-author Malcolm Perry, the paradox "is perhaps the most puzzling problem in fundamental theoretical physics today." It was also Hawking's center of life for many years.

The information paradox is a result of Hawking's theoretical argument back in the 1970s that black holes have a temperature. They evaporate over time until nothing's left, releasing an energy now called the "Hawking Radiation."

It is said that when an object enters a black hole, its information gets preserved on its surface forever even if it's out of sight. If a black hole evaporates, then the information will also vanish. That creates a paradox because according to the rules of quantum physics, information can never be destroyed.

In the latest paper, it is explained how that information can be preserved by photons called 'soft hair' surrounding the edge of the black hole. According to Hawking, Perry, Andrew Strominger, and Sasha Haco, the temperature of the black hole changes when an object (say, a planet's atoms) into it. As it gets hotter, the entropy rises as well. That entropy is what's preserved in a black hole's soft hair.

"It was very difficult for Stephen to communicate and I was put on a loudspeaker to explain where we had got to. When I explained it, he simply produced an enormous smile. I told him we'd got somewhere. He knew the final result," he told The Guardian. The scientists admit that there's a lot of work to be done, though: "It's a step on the way, but it is definitely not the entire answer," Perry said. "We have slightly fewer puzzles than we had before, but there are definitely some perplexing issues left," said Perry.