Black holes have a weird duality: They are objects that are both quite simple and impossibly complex. The simplicity comes from the fact that a black hole is an object so massive that nothing, not even light, can escape its gravitational pull. The complexity comes from when we put that relatively simple notion into the universe. Things go wrong.
A major issue is the so-called information paradox, and it comes from the fact that quantum mechanics and general relativity don’t play well together around a black hole. Relativity tells us that once something crosses the event horizon, the boundary of a black hole, the information related to that thing is lost forever. This doesn’t sit well with the principle of quantum mechanics.
This discussion has raged on for decades with no current solution, simply because quantum mechanics and general relativity, which are incredibly successful in their own fields, can’t be reconciled. One potential solution was the “black hole firewall”, where anything approaching a black hole would hit a wall of high-energy particles. This, it was believed, solves the information paradox, but now researchers are proving that this is unlikely to be the case.
In the Journal of High Energy Physics, researchers from Ohio State University have tackled the firewall scenario by imagining an electron falling inside a black hole that's the mass of the Sun. They calculated that the probability that the electron was hit by a photon of this firewall is extremely low for a realistic black hole.
“What we’ve shown in this new study is a flaw in the firewall argument,” senior author Professor Samir Mathur said in a statement.
“The probability of the electron hitting a photon from the radiation and burning up is negligible, dropping even further if one considers larger black holes known to exist in space.”
The team instead has a different interpretation. They call it the fuzzball argument, and it is a description of black holes according to string theory. In this approach, the event horizon is not a well-defined threshold, but more like a mist made of subatomic strings.
“The question is ‘Where does the black hole grab you?’ We think that as a person approaches the horizon, the fuzzball surface grows to meet it before it has a chance to reach the hottest part of the radiation, and this is a crucial finding in this new physics paper that invalidates the firewall argument,” Samir explained.
The solution, Samir states, is to find in string theory a potential approach that bridges the gap between quantum mechanics and relativity.