Albert Einstein's theories, primarily the theory of relativity, revolutionized our understanding of space, time, and gravity. His famous equation, E=mc², shows that energy and mass are interchangeable, meaning a small amount of mass can be converted into a large amount of energy. This principle underlies many modern technologies, including nuclear power. Einstein's general relativity further explains how massive objects, like planets and stars, warp the fabric of space-time, causing the phenomenon we perceive as gravity. This theory has been confirmed through various experiments and observations, such as the bending of light around massive objects, reshaping our view of the universe.