Quantum theory

basic modern theory of physics that energy is transferred in pulsations

Quantum theory may mean:Old quantum theory under the Bohr modelQuantum mechanics, an umbrella term, particularly for nonrelativistic theoriesQuantum field theory, a generic type of relativistic quantum theory, which includes:Quantum electrodynamicsQuantum chromodynamicsElectroweak interactionQuantum gravity, a general term for theories intended to quantize general relativityQuantum optics
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In physics, quantum mechanics is the study of the relationship between energy quanta (radiation) and matter, in particular that between valence shell electrons and photons. Quantum mechanics is a fundamental branch of physics with wide applications in both experimental and theoretical physics. The effects of quantum mechanics are typically not observable on macroscopic scales, but become evident at the atomic and subatomic level.  Quantum theory generalizes all classical theories, including mechanics and electromagnetism (except general relativity), and provides accurate descriptions for many previously unexplained phenomena such as black body radiation and stable electron orbits.
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Noun
1. (physics) a physical theory that certain properties occur only in discrete amounts (quanta)
(hypernym) scientific theory
(classification) physics, physical science, natural philosophy
(class) uncertainty principle, indeterminacy principle

A theory which has the guiding principle that physical quantities can only have discrete values. It states that nature restricts the values which properties can have; this is known as quantitization. In the everyday world, the size of this quantitization is so small that it goes unnoticed. Only on the scale of sub-atomic particles is it noticeable. Apart from quantization the most familiar concepts of quantum theory are wave-particle duality, Heisenberg's Uncertainty Principle and Pauli's Exclusion Principle.

The concept that energy is radiated intermittently in units of definite magnitude, called quanta, and absorbed in a like manner.