is: a wide-ranging theory that describes the behaviour of mechanical systems (such as a particle moving under the influence of a given potential energy function) in situations where the laws and methods of classical mechanics may be inapplicable. [M6.4, P7.1, P8.3, P10.3]
more formally is: the branch of quantum theory that concerns systems with a finite number of degrees of freedom, and may be contrasted with quantum field theory which concerns systems with an infinite number of degrees of freedom.
may be formulated: in a number of equivalent ways, one such formulation being Erwin Schrödinger's wave mechanics. [M6.4, P7.1, P8.3, P10.3]
was founded: mainly by European physicists between 1925-1927. [M6.4, P7.1, P8.3, P10.3]
is used: mainly in the study of microscopic systems such as molecules, atoms and nuclei. [M6.4, P7.1, P8.3, P10.3]
is characterized: by the existence of a (de Broglie) wave description of matter and by the ensuing Heisenberg uncertainty principle and the impossibility of simultaneously determining the position and momentum of a particle with arbitrarily high precision, thus denying the possibility that an electron in an atom moves in a well defined observable orbit.
is also characterized: by the occurrence of quantized quantities; by the use of probability (as in the Born probability interpretation of the wavefunction); and by inconsistency with Einstein's special theory of relativity.
See quantum and Schrödinger equation.
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