Einstein likened the passage of time to that of a river that slows down or accelerates in its meanders.

He assumed that there should be places where time slows down and others where its speed increases. The proof lies right at the center of the Milky Way. At 26,000 light-years away from us, there is the object with the largest mass in the galaxy. It is a supermassive black hole, Sagittarius A, in which the mass of four million suns exists as a single, infinitely dense point known as a singularity.

The force of gravity is very high, as you get closer. Not even the light can escape him. Such a black hole slows down time more than anything else in the galaxy. Thus a natural time machine is born.

One possibility is to send a fast spacecraft around a black hole or to artificially create a black hole that rotates very quickly. “If it were to go around a black hole, then the ship would consume only half the time that the world outside the black hole lives,” said Stephen Hawking in 2010.

This effect is called gravitational time dilation. According to the Theory of General Relativity, gravity is a curve in space-time. Astronomers regularly observe this phenomenon when studying light traveling near a sufficiently massive object.

These large objects (suns, for example) can bend a straight beam of light. This phenomenon is called the gravitational lens effect. The fact that the events that take place in the universe must involve both space and time determines gravity to affect time. You also have a video about this below: