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1900

The birth of quantum theory

German physicist Max Planck publishes his groundbreaking study of the effect of radiation on a “blackbody” substance, and the quantum theory of modern physics is born.

Through physical experiments, Planck demonstrated that energy, in certain situations, can exhibit characteristics of physical matter. According to theories of classical physics, energy is solely a continuous wave-like phenomenon, independent of the characteristics of physical matter. Planck’s theory held that radiant energy is made up of particle-like components, known as “quanta.” The theory helped to resolve previously unexplained natural phenomena such as the behavior of heat in solids and the nature of light absorption on an atomic level. In 1918, Planck was rewarded the Nobel Prize in physics for his work on blackbody radiation.

Other scientists, such as Albert Einstein, Niels Bohr, Louis de Broglie, Erwin Schrodinger, and Paul M. Dirac, advanced Planck’s theory and made possible the development of quantum mechanics–a mathematical application of the quantum theory that maintains that energy is both matter and a wave, depending on certain variables. Quantum mechanics thus takes a probabilistic view of nature, sharply contrasting with classical mechanics, in which all precise properties of objects are, in principle, calculable. Today, the combination of quantum mechanics with Einstein’s theory of relativity is the basis of modern physics.

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