Uh, thats what we call "Doppelspaltexperiment" here. And it is fucking sick, because it is a proof of the dualism of light, that can be a wave and a particle (photon) at the same time. But even as a particle it doesnt have any mass. Why it still gets swallowed by black holes when it has no mass? Because the space-time is so distorted that the photons are just go directly into the hole, while they move around it. The time there gets so slow that someone who falls in a black hole would see the end of the universe before he gets finally swallowed at the event-horizon.