quantum mechanics Word Originnoun Physics.
- a theory of the mechanics of atoms, molecules, and other physical systems that are subject to the uncertainty principle. Abbreviation: QM
Compare nonrelativistic quantum mechanics, relativistic quantum mechanics. Origin of quantum mechanics First recorded in 1920–25 Related formsquan·tum-me·chan·i·cal, adjective British Dictionary definitions for quantum mechanics quantum mechanics noun
- (functioning as singular) the branch of mechanics, based on the quantum theory used for interpreting the behaviour of elementary particles and atoms, which do not obey Newtonian mechanics
quantum mechanics in Science quantum mechanics
- A fundamental theory of matter and energy that explains facts that previous physical theories were unable to account for, in particular the fact that energy is absorbed and released in small, discrete quantities (quanta), and that all matter displays both wavelike and particlelike properties, especially when viewed at atomic and subatomic scales. Quantum mechanics suggests that the behavior of matter and energy is inherently probabilistic and that the effect of the observer on the physical system being observed must be understood as a part of that system. Also called quantum physics quantum theory Compare classical physics. See also probability wave quantum uncertainty principle wave-particle duality.
quantum mechanics in Culture quantum mechanics
The branch of physics that deals with the behavior of matter at the level of the atom, the nucleus, and the elementary particle. At this level, energy, mass, momentum, and other quantities do not vary continuously, as they do in the large-scale world, but come in discrete units, or quanta. (See Bohr atom and photon.)