Time Dilation Calculator: The Interstellar Effect

One of the strangest truths in physics is that time is not the same for everyone. Move fast enough, or sit close enough to a black hole, and your clock slows compared to everyone else's. This tool lets you feel that effect for yourself.

Two ways to bend time

The first tab uses speed. Einstein's special relativity says that the faster you move, the slower your time runs relative to those at rest. At everyday speeds the effect is tiny, but approach the speed of light and it becomes enormous.

The second tab uses gravity near a black hole. Close to a black hole's event horizon, the warping of spacetime slows time dramatically for anyone who lingers there. This is the effect dramatised in the film Interstellar, where an hour on a planet near the black hole equals seven years for those far away. For more on his thinking here, see Hawking on time travel and the science of Interstellar.