German physicist and professor Max Planck (1858–1947) originated and developed the quantum theory (from 1900), for which he was awarded the Nobel prize in physics in 1918. The basic theory is that energy and some other physical properties can exist in tiny, finite amounts (called quanta). Before Planck’s work, theories of classical physics held that energy and physical properties varied continuously. Planck experimented with black-body radiation (a black body is any substance that absorbs all of the radiant energy that falls on it, reflecting none of it). He concluded that radiant energy can be divided, and the particles (quanta) would have values proportional to those of the energy source; Planck determined the relationship between the amount of energy that light has and its frequency. Along with Albert Einstein’s (1897–1955) theory of relativity, the quantum theory forms the basis of modern physics. Since it was developed, the quantum theory has been applied to numerous processes involving the transfer of energy in an atomic or molecular scale, including in 1913 when it was used by Danish physicist and Nobel laureate (1922) Niels Bohr (1885–1962) to explain atomic structure. The theory has been used to explain how electrons move though the chips in a personal computer, the decay of nuclei, and how lasers work.