Astronomy Fundamentals

Quantum Mechanics

How did Albert Einstein contribute to our understanding of matter and quantum mechanics?

In 1905 Albert Einstein published not only his special theory of relativity, but also two other theories that became part of the fundamental understanding of matter in the universe. In one of the two theories, he explained that Brownian motion—the seemingly random jiggling motions of microscopic fat globules suspended in milk or water—were caused by individual atoms and molecules moving around the suspension, striking the globules and causing them to move. In the other theory, he explained that the photoelectric effect—in which light of certain colors striking sheets of metal would produce electric currents, whereas light of other colors would not—was caused by light acting as both a wave and a particle. The Brownian motion result further helped prove the existence of atoms; and the photoelectric effect result showed that new physical ideas, such as quantum mechanics, were necessary to explain the nature and behavior of light.


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