Einstein's theory of relativity is our most accurate way of describing how matter, energy, space, and time interact. It is actually two theories: special and general relativity. Special relativity came first. This said nothing can travel faster than the speed of light. It also showed that the passage of time is different for people traveling at different speeds. According to the theory, if twins are separated by one taking a journey through space at close to the speed of light, they will have significantly different ages when reunited later. Special relativity also spawned the famous equation E=mc2, which describes how matter can be converted into energy, and vice versa.This equation laid the foundations for the atomic bomb and nuclear power.
The later theory, general relativity, overthrew Isaac Newton's concept of gravity. It portrays time as a dimension, just like the three dimensions of space, and combines them all into something called space-time. Anything with energy or mass warps space-time, creating a gravitational field. Such a field has an effect on any matter traveling through it. It even bends passing light rays in a process called gravitational lensing. The first proof of relativity came with the observation of this phenomenon during a solar eclipse in 1919.by Michael Brooks, 30 Second Theory