An event horizon is the point of no return for a black hole. As the spaceship nears this point, time slows down to a crawl relative to an observer on Earth. This phenomenon has been observed in many experiments and is called “time dilation.” The time dilation is even more pronounced than for objects on Earth.
As the spaceship gets closer to the event horizon, an observer outside of the black hole will see a clock moving in slow motion until it appears that there’s no movement at all as it reaches its point of no return and falls into oblivion. This person won’t be able to tell how long this has been happening because their own experience with time doesn’t allow them to measure any interval greater than two seconds.
It just seems like they’ve blinked once or twice before the object disappears from sight forever. The same thing happens inside a black hole–time slows so much near these points that people would have difficulty telling whether one year had passed for every second in reality or if