We all live in a space time continuum i.e every incident happens at some time and particular space the questions is :- can time become slow according to Einsteins's theory of relativity time can become slow due to gravitational force let us understand this with an example.

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Think time as a sheet of water formed by a river there is a planet in mid of this river which have some gravitational force because of it that sheet of water will become curved and the water will take more time to reach the other end of the planet because the curvature will increase the distance between them.

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This sheet water is time i.e time will become slow scientists have proven this with experiments, It is known as gravitational time dilation, because of it clocks on satellites tick faster than earth's as there's low gravitational force around the satellites so clocks on satellites are repeatedly adjusted according to the clocks on earth.

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If we want to see gime become more slower than we need more gravitational force which we will found only near black hole, because it have more gravitational force than any other planet in the universe, which can make time very slow, scientists believe that black hole can be used for time travelling If in future we became able to make a spacecraft that can reach to black hole and revolve around it and if we live in that spacecraft for one year till then earth will experience ten years of time and after that if we reach on earth we will manage to do a time travel of 9 years in future.