Event Horizon

If you jump off a cliff, the moment you push off the ground is the point of no return; unless you’re a cartoon character, there’s no going back. Astronomy offers its own point of no return: the event horizon of a black hole. Pass through it and you’ll never see the outside universe again. A black hole is an object in which gravity overwhelms all the other forces of nature. The object’s entire mass — which can range up to billions of times the mass of the Sun — is squished into a pinpoint called a singularity. Anything that comes close enough to the singularity is trapped forever by its gravitational grip. The point of no return is the event horizon — the distance from the singularity where the escape velocity equals the speed of light. In essence, that makes it the surface of the black hole — the boundary between what’s inside the black hole and what’s outside. Even getting close to an event horizon would produce some interesting effects. For one thing, time would begin to pass more sl