Meaning of QUANTUM MECHANICS in English

QUANTUM MECHANICS

noun plural but singular or plural in construction

1. : the mechanics of phenomena to which the quantum theory may be applied — called also old quantum mechanics

2. : a general mathematical theory dealing with the interactions of matter and radiation in terms of observable quantities only (as the intensities and frequencies of spectral lines) — called also new quantum mechanics ; compare atomic theory , matrix mechanics , wave mechanics

Webster's New International English Dictionary.      Новый международный словарь английского языка Webster.