nonQM

NonQM is a shorthand term used in physics and related discussions to designate theories, models, or descriptions that do not employ the principles of quantum mechanics. The term is informal and varies in usage, but it is often used to contrast non-quantum or classical descriptions with quantum-mechanical ones.

Typical contexts include classical mechanics, classical electrodynamics, and other classical field theories, as well as macroscopic limits in which quantum effects are negligible. In these contexts, nonQM models aim to capture phenomena with established classical formalisms such as Newton's laws, Maxwell equations, or Einstein's theory of general relativity treated without quantization.

NonQM is also invoked in debates about the completeness of quantum theory and the transition between quantum and classical behavior. While quantum mechanics is the standard framework for microscopic phenomena, nonQM descriptions remain essential in engineering, fluid dynamics, and cosmology where classical approximations are sufficiently accurate.

Limitations of nonQM approaches are clear: they cannot account for intrinsic quantum phenomena such as superposition, entanglement, and the probabilistic nature of measurement, which quantum theory explains successfully at small scales. Nonetheless, nonQM concepts continue to play a role in teaching, modeling large-scale systems, and in discussions about the interpretation and limits of quantum theory.

See also: quantum mechanics, classical mechanics, classical electrodynamics, general relativity, quantum-to-classical transition.