Black holes are not eternal: they slowly lose energy, emitting entropy — a measure of hidden information — as heat. This process was predicted by Stephen Hawking. But until now, it remained a mystery what happens at the very end, when the hole has almost disappeared and must return the captured data.

Now physicists have shown: after the main mass evaporates, a tiny white hole remains. Like a dying ember, it slowly releases information. The time for this 'cleanup' grows with the mass of the original black hole far more steeply than previously thought.

Perhaps we will be able to see the faint radiation from these remnants — maybe they are hiding under the mask of dark matter.