Gravity influences time through a phenomenon known as gravitational time dilation. According to Einstein's theory of general relativity, gravity is not just a force but rather the curvature of spacetime caused by massive objects. This curvature affects the flow of time, resulting in time dilation.
The fundamental idea is that the presence of a massive object, such as a planet, star, or black hole, creates a distortion in the fabric of spacetime around it. This distortion causes clocks closer to the massive object to run slower compared to clocks further away. In other words, time passes at a different rate depending on the strength of the gravitational field.
The reason for this gravitational time dilation lies in the concept of energy. In general relativity, mass and energy are interchangeable, and the presence of mass or energy curves spacetime. As clocks measure the passage of time by comparing different energy states, the curvature of spacetime caused by gravity affects the energy levels and, consequently, the ticking rate of clocks.
To understand this concept more intuitively, consider a scenario where two identical atomic clocks are placed at different altitudes—one at sea level and the other at a higher elevation. The clock at the higher elevation, experiencing weaker gravitational pull, will tick slightly faster than the one at sea level.
Gravitational time dilation has been observed and verified through various experiments and observations. For instance, experiments using highly precise atomic clocks on Earth and in space have demonstrated the minute time differences caused by the difference in gravitational potential.
Additionally, phenomena like gravitational redshift and gravitational time dilation near black holes provide further evidence of the influence of gravity on time. Near the event horizon of a black hole, where the gravitational field is extremely strong, time dilation becomes significant, causing time to appear to slow down from the perspective of an outside observer.
In summary, gravity influences time through gravitational time dilation, which occurs due to the curvature of spacetime caused by massive objects. This phenomenon leads to clocks running at different rates in regions with different gravitational potentials, with time passing more slowly in stronger gravitational fields.