In November 1915, Albert Einstein completed his general theory of relativity and transformed the world of physics. This theory took Einstein’s earlier theory of special relativity, which applied only to objects in a constant state of motion, and generalized it to account for acceleration (hence the name general theory of relativity).
But what’s so special about special relativity? In a nutshell, it introduced the idea that space and time are relative. Einstein thought of space and time as one entity, which he referred to as space-time, and found that rather than it being an immutable cosmic stage, space-time is affected by motion. This means, for example, that if you were traveling at close to the speed of light, time would pass more slowly for you than for an observer standing on Earth.
Walter Isaacson, author of Einstein: His Life and Universe, explains how Einstein came to this radical notion and revolutionized our understanding of the universe.
Fusion’s original Relatively Speaking series celebrates the 100th anniversary of Albert Einstein’s general theory of relativity.