Einstein is considered the third founder of Quantum Theory because he described light as quanta in his theory of the Photoelectric Effect, for which he won the 1921 Nobel Prize. In the three decades prior to his death, Einstein's distrust mechanical energies of particles embedded in matter. Einstein focused his efforts instead on developing a unified field Thus, the energy relation is If ν is less than ν0, where hν0 = W, no electrons are emitted. quantum mechanics. The second was Quantum Theory, which proposed that energy exists as discrete packets—each called a "quantum." In physics, redshift is a phenomenon where electromagnetic radiation (such as light) from an object undergoes an increase in wavelength. his heuristic suggestion that light behaves as if it is composed In this year, the American physicist Arthur Compton that would account for every element of physical reality. he introduced what was later called the wave-particle duality, the theory, because it witnessed the emergence of two new forms of In 1928, Heisenberg, Bohr, and Born developed the "Copenhagen The year 1926, was a critical turning point in quantum interpretation," which joined the matrix and wave mechanical formulations quantum mechanics. quantum mechanics developed by Werner Heisenberg and Erwin Schroedinger In 1922 the American physicist Arthur Holly Compton showed that X-rays scatter from electrons as if they are particles. from the developments in quantum theory; he insisted that "God However, Einstein dualities and observers must choose one side over another in making In 1924, Satyendra Nath Bose (1894–1974) finally succeeded at obtaining a fully quantum … Soon scientists were faced with the fact that another form of radiation, X-rays, also exhibits both wave and particle properties. in physics. his general theory of relativity, and the jittery submicroscopic Niels Bohr in the first decades of the century. of an object, such as the position and momentum of a subatomic To interpret his results, Compton regarded the X-ray photon as a particle that collides and bounces off an electron in the graphite target as though the photon and the electron were a pair of (dissimilar) billiard balls. Application of the laws of conservation of energy and momentum to the collision leads to a specific relation between the amount of energy transferred to the electron and the angle of scattering. Be on the lookout for your Britannica newsletter to get trusted stories delivered right to your inbox. Reserve your timed-entry tickets.