According to Stephen Hawking, we’ve got black holes all wrong.
As far as we are concerned, a black hole is a structure in space with an event horizon past which no light or matter can escape and ends up being devoured. Hawking is proposing that instead of having a clear ‘event horizon’, black holes actually have an ‘apparent horizon' which constantly fluctuates due to quantum effects.
One of the nifty consequences of this theorised model is that it resolves the firewall paradox which can be easily explained by considering an unfortunate astronaut falling into the event horizon of a black hole (RIP Mr. Astro).
Classical physics tells us that this poor soul would be stretched out and spaghettified (yes, this is a real word) until being crushed at the infinitely dense core. Quantum theory, however, suggests that the event horizon of a black hole would be a highly energetic reason and would act as a ‘firewall’ causing the astronaut to be burned to a crisp.
This is a big problem because it violates the equivalence principle which tells us that free falling is indistinguishable from floating in empty space (which obviously is not the case if find yourself being burned to a crisp). Another solution to the paradox suggests that information is simply lost in a black hole, but this is also very controversial as it violates unitarity.
Apparently, Hawking’s paper resolves this paradox. By replacing the event horizon with an apparent horizon, the theorised firewall can no longer exist as there is no uniform boundary to the black hole. However, the paper consists of just two pages with no calculations so it is very difficult for anyone to draw any definite conclusions. Some theorists have suggested that this theory could raise even more radical issues than the existence of firewalls.
If Hawking’s past discoveries are anything to go by, this could turn into a very interesting debate.