Watch a team of physicists try to prove one of Albert Einstein’s predictions of general relativity—that heavy objects distort time—in this video from NOVA: Inside Einstein’s Mind. Einstein’s theory holds that time speeds up as we travel away from the mass of a planet and gravity weakens. To test this, the physicists place two atomic clocks at different elevations on Earth. After four days, the difference between the clocks' ticks is slight but measurable. Using the Global Positioning System (GPS) as an example, the video also explains how time distortion can impact our daily lives.