quantum mechanics

quantum mechanics   n.   (used with a sing. or pl. verb) Quantum theory, especially the quantum theory of the structure and behavior of atoms and molecules.

Main Entry: quantum mechanics
Function: noun plural but singular or plural in construction
: a theory of matter that is based on the concept of the possession of waveproperties by elementary particles, that affords a mathematical interpretation of the structure and interactions of matter on the basis of these properties, and that incorporates within it quantumtheory and the uncertainty principle called also wave mechanics —quantum mechanical adjective —quantum mechanically adverb

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.