quantum mechanics

American  

noun

Physics.

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

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quantum mechanics British  

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

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quantum mechanics Scientific  

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

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quantum mechanics Cultural  

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.)

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Other Word Forms

• quantum-mechanical adjective

Etymology

Origin of quantum mechanics

First recorded in 1920–25

Example Sentences

Because photons behave according to quantum mechanics, their polarization cannot be measured without leaving detectable traces.

From Science Daily

Things got weirder, though, when the mathematics of quantum mechanics suggested that measuring one particle might instantaneously influence the state of another particle far away.

From Scientific American

In quantum mechanics, figuring out what’s going on with more than a few particles at the same time is notoriously difficult.

From Scientific American

In a recent video, physicist Sabine Hossenfelder, whose work I admire, notes that superdeterminism eliminates the apparent randomness of quantum mechanics.

From Scientific American

They tend to interpret this breakdown of the math to mean that some as yet unknown physics, which likely involves quantum mechanics, takes over near the singularities.

From Scientific American