quantum theory Physics.
[f. quantum + theory1.]
A theory of matter and energy based on the concept of quanta (sense 5); spec. the branch of physics that was developed from the ideas in Planck's paper of 1900 and Einstein's of 1905 (see quantum 5), was extended by Bohr (1913) in relation to atomic structure, and later evolved into quantum mechanics and quantum field theory; old quantum theory, the early form of the theory, based on classical mechanics, prior to the development of wave mechanics and matrix mechanics in the mid-1920s.
| [1911 Sci. Abstr. A. XIV. 1702 The quanta theory of Planck and Einstein must be modified considerably to give a quantitative interpretation of the results obtained.] 1912 Monthly Notices R. Astron. Soc. LXXII. 677 The constant of nature in terms of which these spectra can be expressed appears to be that of Planck in his recent quantum theory of energy. 1926 Times Lit. Suppl. 19 Aug. 544/3 Relativity theory and quantum theory have not yet been properly assimilated. 1927 Proc. R. Soc. A. CXIV. 181 This equation..was obtained orginally by Sommerfeld from relativistic considerations with the old quantum theory. Ibid. 243 The new quantum theory, based on the assumption that the dynamical variables do not obey the commutative law of multiplication, has by now been developed sufficiently to form a fairly complete theory of dynamics. 1958 W. Heisenberg Physics & Philos. vi. 106 Quantum theory does not allow a completely objective description of nature. 1970 G. K. Woodgate Elem. Atomic Struct. vi. 103 For small l the electron orbit is highly eccentric (to use the language of the old quantum theory). 1972 Physics Bull. Sept. 548/1 This book consists of five short chapters, on classical mechanics and the old quantum theory, the new quantum theory, many particle systems, valence theory and quantum theory of chemical reactivity. 1978 Sci. Amer. Feb. 132/3 Quantum theories of the gravitational force still have serious difficulties with infinities. |
Hence quantum-theoretical a., quantum-theoretically adv.; quantum theorist, an expert or specialist in quantum theory.
| 1920 Chem. Abstr. XIV. 1637 (heading) Quantum theoretical principles of photochemistry. 1931 Physical Rev. XXXVIII. 1787/1 No quantum theoretical calculations have been made for particles of very high energy. 1935 Amer. Jrnl. Math. LVII. 429 The algebra II is known to the quantum theorist from the process of ‘superquantizing’. 1939 G. Herzberg Molecular Spectra & Molecular Struct. I. iii. 84 Quantum theoretically, emission of radiation takes place as a result of a transition of the oscillator from a higher to a lower state. 1959 K. R. Popper Logic of Sci. Discovery ix. 222 In his derivation of the uncertainty relations, Heisenberg follows Bohr in making use of the idea that atomic processes can be just as well represented by the ‘quantum-theoretical image of a particle’ as by the ‘quantum-theoretical image of a wave’. 1968 G. Ludwig Wave Mech. i. ii. 19 These classical results were transformed by Bohr into quantum-theoretical results. 1976 Nature 1 July 17/1 General Electric advertised for a quantum theorist to look into the fundamental quantum processes involved in fluorescence. |