Black holes are a phenomenon that the greatest scientists of our time have tried to understand, but is proving to be quite the challenge.
However, after many years of thought put into it, there were some theories that were thought to be true. But then came none other than Stephen Hawking, and turned the world upside down.
Up until now, it was believed by most that black holes have something called the event horizon, an imaginary line where nothing that crosses it can go back, even light. Hawking, in his most recent paper “Information Preservation and Weather Forecasting for Black Holes”, says that there is no such thing as an event horizon, but rather an apparent horizon. Basically, it’s the same thing, but less strict in shape (due to continuous quantum fluctuations) and which can occasionally let matter and energy out but changing them enough so they can’t be recognized.
The black hole puzzle has been treated using our two basic physical theories: quantum mechanics and general relativity. However, these two laws don’t get along that well, so when you mix them, anything can happen.
In this case, the weird happened when a black hole evaporates. Quantum mechanics says that matter (or information) cannot be lost, so it would leave the black hole through radiation. But in doing so, it would release outstandingly high amounts of energy, creating, literally, a firewall. But general relativity says that you can’t cross an event horizon, and this disagreement between the theories creates a paradox. Or as it is commonly known, the firewall paradox.
Let’s put it this way. If an astronaut was falling down into a black hole, quantum mechanics says that it would die of radiation and burning thanks to the firewall. General relativity says that it will be trapped in the black hole, since it can cross back the event horizon, and will die of the extreme gravitational conditions inside this phenomenon. In either case, our space explorer doesn’t survive, but in different ways.
The famous scientist has proposed the existence of this apparent horizon to solve this problem. If it was true, it would cancel the paradox, but it would create something else.
With this new horizon, matter or energy could escape, but it would also scramble them up, because of a black hole’s gravity, so even though they could potentially get out, they will have been so messed up that they could not be reconstructed. It would not be destroyed, so it agrees with quantum mechanics, but it’s original structure will be lost.
This polemic statement has already provoked a response from many scientists, since it would completely change our current definition of a black hole, a region in space from which nothing can escape; or so it was thought.