In their latest video, Kurzgesagt takes a look at black holes, specifically how they deal with information. According to the currently accepted theories, one of the fundamental laws of the Universe is that information can never be lost, but black holes destroy information. This is the information paradox…so one or both of our theories must be wrong.

The paradox arose after Hawking showed, in 1974-1975, that black holes surrounded by quantum fields actually will radiate particles (“Hawking radiation”) and shrink in size (Figure 4), eventually evaporating completely. Compare with Figure 2, where the information about the two shells gets stuck inside the black hole. In Figure 4, the black hole is gone. Where did the information go? If it disappeared along with the black hole, that violates quantum theory.

Maybe the information came back out with the Hawking radiation? The problem is that the information in the black hole can’t get out. So the only way it can be in the Hawking radiation (naively) is if what is inside is copied. Having two copies of the information, one inside, one outside, also violates quantum theory.

So maybe black holes holographically encode their information on the surface?