The history of black holes isn’t very long. 100 years ago, no one knew about black holes. Because of Einstein’s Theory of Relativity, black holes were later discovered. There are two parts to the theory. The Special Theory of Relativity, and the General Theory of Relativity. The Special Theory of Relativity published by Einstein in 1905, tells us how speed influences time.
If you are in a spaceship that is going very fast, if the speed is too high, time will slow down for you. Relative to the people not on the spaceship, back on Earth. The word relative is very important because when you are in a spaceship, you wouldn’t feel the time slowing down. You would think that time is flowing at the same speed as it normally does.
But when you’ll get back to the Earth, you’ll find out that there was a difference in the flow of time. This is known as Kinematic Time Dilation. Not only speed, but even gravity can also result in time dilation as shown by Einstein in his General Theory of Relativity. This was developed by him in 1915. The more gravitational force you’d experience, the more time would slow down for you. This is known as Gravitational Time Dilation. And this was depicted amazingly in Interstellar.
