While on a quest to save the human race, astronauts in the film Interstellar travel to a foreign planet orbiting closely around a supermassive black hole. Due to the strong gravity, time on the planet is distorted, being artificially compressed. Seven entire years here on Earth are squeezed down to just one hour of time on the planet.
This is one of the many bizarre effects of Einstein's general theory of relativity, referred to as gravitational time dilation. I had some students from my physics class recently ask me to explain this phenomenon. So I prepared what I think is a fairly straightforward explanation of the phenomenon, assuming only a knowledge of 1st semester physics and some simple calculus.
