Are black holes surrounded by a firewall?

Black holes suck in anything that gets too close to them—even light. In their interiors, researchers imagine objects that, according to current physics, should not even exist: singularities, where matter becomes infinitely dense and hot and classical physics breaks down. The area around a black hole is also a hot subject of discussion. In particular, astrophysicists run into problems when they consider a black hole simultaneously with the general theory of relativity and quantum physics.

One...