Final answer:
According to Einstein's general theory of relativity, a clock that ticks at a regular rate far from a source of gravity will appear to tick slower the closer it comes to the source of gravity. This has been confirmed in experiments both on Earth and in space.
Step-by-step explanation:
According to Einstein's general theory of relativity, a clock that ticks at a regular rate far from a source of gravity will appear to tick slower the closer it comes to the source of gravity. This prediction has been tested in experiments both on Earth and in space. For example, in an experiment in 1959, atomic clocks on different floors of a building at Harvard University were compared, and the clock closer to the center of gravity ran slightly slower. Similarly, atomic clocks on satellites in space run slightly faster than clocks on Earth due to the weaker gravity.