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 physicsSee also probability wave

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 Words From

• quantum-me·chani·cal adjective

Word History and Origins

Origin of quantum mechanics¹

First recorded in 1920–25

Example Sentences

The Bell theorem refers to how entangled electrons are predicted by quantum mechanics, making them non-local — often referred to as “spooky action at a distance.”

From Salon

They are ideally suited for predicting the structure and behavior of molecules, researchers say, because both the machines and the molecules are ruled by the counterintuitive laws of quantum mechanics.

From Science Magazine

Each of these particles follows the rules of quantum mechanics.

From Science Daily

Since the discovery of quantum mechanics more than a hundred years ago, it has been known that electrons in molecules can be coupled to the motion of the atoms that make up the molecules.

From Science Daily

Britain, China, the US and countries elsewhere, are all trying to exploit the weird properties of quantum mechanics.

From BBC