In physics, the theory that energy does not have a continuous range of values. It is instead absorbed or radiated discontinuously in multiples of discrete and indivisible units or packages called quanta. Previous theories had shown how light, depicted as a wave motion, could also be regarded as composed of discrete particles. Quantum mechanics, for its part, also showed that how atomic particles such as electrons could have the dual property of waves and particles. A major claim of the theory is that all phenomena on small scales follow probabilistic dictates termed quantum rules, a claim in recent years that been applied to the functioning of the brain. The impact of quantum mechanics on science in general derived from its stress on probabilistic explanations, which brought about new ways of thinking about causality (the ‘stochastic revolution’). Through this and other features of theory, it has influenced a broad spectrum of science, not only within physics (e.g., particle physics), but also outside the discipline. One example is psychology, or more specifically philosophical psychology, and the way some of its practitioners approach the mind-body problem. An extension of statistical mechanics, it arose due the failure of newtonian mechanics and electromagnetism theory to deliver a consistent explanation of electromagnetic waves and atomic structure.
See Causality (philosophy), Dualism, Explanation, Implicate order, Mind-body problem, Statistical mechanics, Stochasticity