quantum mechanics

noun

Physics.

1. a theory of the mechanics of atoms, molecules, and other physical systems that are subject to the uncertainty principle. QM

quantum mechanics

noun

1. (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

1. 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.

2. Also called quantum physics quantum theory

3. Compare classical physics See also probability wave quantum uncertainty principle wave-particle duality

quantum mechanics

1. 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.)

Other Word Forms

• quantum-mechanical adjective

Word History and Origins

Origin of quantum mechanics¹

First recorded in 1920–25

Example Sentences

However, quantum computers, whose operations are governed by the principles of quantum mechanics, are far more delicate.

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“Unlike traditional computers, quantum systems operate by the laws of quantum mechanics, which opens up a richer mathematical space for problem-solving,” she wrote today.

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Unlike traditional computers, quantum systems operate by the laws of quantum mechanics, which opens up a richer mathematical space for problem-solving.

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Einstein's theory of relativity replaced that classical model, and quantum mechanics transformed it yet again.

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That's because quantum mechanics - a strange and partly theoretical branch of physics - is a fiendishly difficult concept to get your head around.

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