# At last, some details on Stephen Hawking’s solution to black hole problem

Stephen Hawking has finally provided more information about how black holes might preserve information. Following up on an intriguing talk he gave in August, the 74-year-old physicist coauthored a paper posted January 5 to arXiv.org describing how someone outside a black hole may be able to learn what’s inside.

A complication in determining a black hole’s contents is that black holes are thought to be nondescript, distinguishable by only three features: mass, spin and electric charge. Hawking, along with Andrew Strominger from Harvard and Malcolm Perry from Cambridge, now posits that a hologram made of light gives a black hole its identity. The light, which is stuck on the black hole’s boundary, acts like a hard drive to store information about everything that enters the abyss.

The researchers admit they still have to prove that an observer could use this hologram to decipher everything inside the black hole. Juan Maldacena, a theoretical physicist at the Institute for Advanced Study in Princeton, N.J., says the paper is “a piece in the puzzle … to completely understand the quantum mechanics of black holes.”