He was the greatest mind and paramount icon of our age, the kindly, absentminded professor whose wild halo of hair, piercing eyes, engaging humanity and extraordinary brilliance made his face a symbol and his name a synonym for genius: Albert Einstein.
During his spare time as a young technical officer in a Swiss patent office in 1905, the young German produced three papers that changed science forever. The first described how light could behave not only like a wave but also like a stream of particles, called quanta or photons. This wave-particle duality became the foundation of what is known as quantum physics. It also provided theoretical underpinnings for such 20th century advances as television, lasers and semiconductors. The second paper confirmed the existence of molecules and atoms by statistically showing how their random collisions explained the jerky motion of tiny particles in water.
(PHOTOS: The Lighter Side of Albert Einstein)
But it was his third paper that truly upended the universe. It was based, like much of Einstein’s work, on a thought experiment: no matter how fast one is moving toward or away from a source of light, the speed of that light beam will appear the same, a constant 186,000 miles per second. But space and time will appear relative. The special theory of relativity went on to show that energy and matter were merely different faces of the same thing, their relationship defined by the most famous equation in physics: energy equals mass multiplied by the speed of light squared, E=mc². Although not exactly a recipe for an atom bomb, the theory explained why one was possible.
In 1916 Einstein published his general theory of relativity, which posited gravity as a warping of space-time. It took three years for astronomers to prove the theory by showing how the sun’s gravity shifted light coming from a star. The results were announced at a meeting of the Royal Society in London presided over by J.J. Thomson, who in 1897 had discovered the electron. After glancing up at a grand portrait of Sir Isaac Newton, Thomas told the assemblage, “Our conceptions of the fabric of the universe must be fundamentally altered.”
This entry is excerpted from the new TIME book The 100 Most Influential People of All Time, which profiles spiritual icons, leaders, explorers, visionaries and cultural titans throughout human history. Available wherever books are sold and at time.com/100peoplebook