UC Santa Barbara Physics Professor, Steve Giddings, recently wrote for Scientific American.
According to quantum mechanics, information can never be destroyed. But when combined with general relativity, quantum rules say that black holes destroy information.
Scientists have proposed modifications to the classical picture of black holes that could solve the paradox, but they lack evidence to test them.
That is changing with the new Event Horizon Telescope, which recently took the first picture of a black hole, as well as with gravitational-wave measurements of black holes colliding.