Gravitational time dilation is a key prediction of Einstein’s general theory of relativity, which states that time passes more slowly in stronger gravitational fields. In other words, the closer you are to a massive object (like a planet, star, or black hole), the slower time flows for you compared to someone farther away.
This effect occurs because gravity curves spacetime. Clocks placed in a deeper gravitational well (closer to the massive object) tick more slowly relative to clocks farther away. This isn’t just a theoretical idea—it’s been experimentally confirmed, such as by comparing atomic clocks on Earth’s surface and in orbit.
Gravitational time dilation becomes especially dramatic near extremely dense objects. For example, near the event horizon of a black hole, time could slow down so much that a distant observer would see the falling clock freeze in time.
This phenomenon has practical applications too. GPS satellites, for example, must account for both gravitational and velocity-based time dilation to provide accurate positioning. Without these relativistic corrections, GPS errors would quickly accumulate, making the system unreliable.
Gravitational time dilation reveals how gravity affects not just space, but time itself, fundamentally altering our understanding of how the universe operates.