Of all the unsolved problems in physics, the black hole information paradox feels most like a whodunit. It’s a classic locked room mystery, and the victim in this case is quantum information.

Imagine a man goes inside a room and gets locked in. The police arrive at the scene and go in to find no trace of the man. Instead there are some bricks, a coffee machine and a dictionary (or any other set of random items) whose combined weight equals that of the man. Mass has been conserved – but without any trace of the man himself, no one can figure out his identity or how he vanished. This happens every time someone goes into one of these rooms: they disappear leaving behind a random set of items. The identity of the person is simply lost.

The black hole information loss paradox is a mystery along similarly bizarre lines.

To read more, click here.