An astronaut can plunge from a hovering spacecraft down to the surface (horizon) of a giant black hole in a few hours or days. To the waiting colleagues, her signals get more and more delayed and redshifted and weakened so as if she reached the horizon only after infinite time. These facts are known since Oppenheimer and Snyder’s famous 1939 paper which established the existence of black holes.
No one ever thought of asking the return question: Assume that a trampoline is mounted right above the horizon so that the astronaut returns on a symmetric trajectory after the very number of hours it took her to descend. How long will the crew mates have to wait until they can re-embrace her?
This is the zillion dollar question the scientific community forgot to ask for 76 years. You guess the answer: after zillions of years. This is the ultimate twin paradox.
Hence all general-relativity textbooks need to be re-written. Suddenly, there is no finished black hole anymore (only almost-finished ones). Without finished horizon, there is no Hawking radiation, no singularity, no information paradox, no Kerr solution, and no CERN safety.
The most high-browed profession with the largest trust bonus and money budget flunked a simple IQ test. How long will it take until the world media are allowed to report on this?