Blackhole

An hour spent near a black hole is equivalent to millions of years on Earth. This phenomenon is a key prediction of Albert Einstein's theory of general relativity, and is called time dilation. The theory explains that time moves more slowly as the intensity of gravity increases. Since black holes are the most gravitationally powerful objects in the universe, this effect is particularly large there.

Imagine an astronaut traveling very close to the event horizon of a black hole. To someone observing this astronaut from Earth, his time would seem to move very slowly. Gravity warps the fabric of spacetime near the black hole. Because of this warping, the astronaut's time would move much more slowly than time for someone on Earth.  If an astronaut sees only one minute on his watch, millions of years may have passed on his watch on Earth.

This is not a science fiction concept, but a reality proven by the theory of relativity. Even on Earth, a small form of this happens. For example, for people on top of a very high mountain, time passes slightly faster than for people in the valley. That is, because they are further from the center of the Earth, the force of gravity is slightly less. This time dilation also occurs in GPS satellites. Because they are so far from Earth, their clocks run slightly faster than clocks on Earth. The GPS system works by taking this difference into account. The gravity near black holes makes this effect very intense.

The Hollywood movie Interstellar depicts this phenomenon very accurately. An example of this is when the main characters in the movie spend a few hours on a planet near a black hole, while decades pass on Earth.  Therefore, it is not only theoretically but also scientifically possible that an hour spent near a black hole could be felt on Earth for millions of years.