General relativity is a theory published by Albert Einstein in 1915. Through it, one can say that gravity is a curvature in space due to the presence of masses.
The closer you are to a mass, the slower time will pass. Idea of time travel.
Black hole is a massive star with very high gravity. In the film is called the Gargantua. Do not have solid surface. Singularity is central point of a black hole. In the center of our galaxy there is a black hole, called Sagittarius A*.
Used to understand the “things” large and small. Calm the turbulences in the range of Plank.
Watch the movie, is fantastic.