Video narration
Einstein’s relativity comes in two parts: special relativity and general relativity. Special relativity starts with one surprising rule: the speed of light is always the same, no matter how fast you’re moving. To make that possible, space and time can “flex.” If you move very fast, time for you can tick a little slower compared with someone standing still—this is called time dilation. General relativity adds gravity. Instead of thinking of gravity as an invisible pull, Einstein said mass and energy bend spacetime, like a heavy ball curving a stretchy sheet. Objects—and even light—follow those curves, which looks to us like gravity. The big takeaway: space, time, motion, gravity, and light are linked—and that changed how we understand everything from GPS to black holes.