Stephen Hawking, the world’s most famous living physicist, thinks he has solved a mystery. It’s one that has puzzled scientists for more than 40 years: What happens to information about matter as it falls into a black hole?
Black holes are regions in space that contain huge amounts of matter. All that mass is packed together very tightly. The result is that a black hole’s gravity is so strong that not even light can escape. So if you fell into a black hole, you’d die. (Don’t worry, though. A person would never actually come anywhere near a black hole!)
But black holes don’t last forever. In the 1970s, Hawking showed that the energy in black holes slowly leaks away into space. It “evaporates” until nothing is left. It does this through a process now known as Hawking radiation.
The same thing should be true of the information about matter inside a black hole, such as its shape or its electrical charge. If the matter inside a black hole disappeared, so should any record of what had been inside it.
But that would defy a basic law of how the universe works. That law says that information is never lost. So the idea that information in a black hole could simply evaporate posed a major problem. Physicists called it the information paradox. (A paradox is an idea or a statement that is true, but seems logically impossible.)
Now, Hawking claims that he and two colleagues have solved that information paradox.
