While there are lots of theories about black holes, a staple of singularity lore is that all black holes have event horizons — a one-way membrane through which particles fall in, never to return. Einstein’s theory of general relativity says that all black holes have an event horizon where nothing, not even light, can escape the gravitational pull of these extremely dense objects.
But some have cast doubt about the existence of these event horizons. Stephen Hawking, one of the architects of modern black hole theory, wrote a paper in 2014 arguing that event horizons are incompatible with quantum theory. He instead proposed a more benign “apparent horizon,” which only temporarily holds matter and energy.
Another proposed alternative to event horizons is the “hard surface theory,” which suggests that matter within a black hole is destroyed by smashing into a solid surface. Instead of a singularity with no surface area, the black hole is a giant mass with a hard surface, and material being pulled closer — such as a star — would not actually fall into a black hole, but hit this hard surface and be destroyed. If that were the case, the collision should create a large burst of light.
But if event horizons do exist, there wouldn’t be flash of light. Instead, matter would just completely vanish when pulled in.