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The term quantum system generally indicates particles and fields within some specific time interval, that fall within a region of atomic scale or less and have some separation from other similar particles. The term is used to indicate everything affected by a quantum-mechanical interaction of interest. This is analogous to classical-physics terms such as dynamical system, used indicate "all the things significantly affecting each other via Newton's laws"; for example, an analysis of the dynamics of the solar system planets would include the Sun, but exclude Alpha Centauri as insignificant due to the separation. For quantum interactions, factors such as de Broglie wavelengths, and quantum entanglement can be relevant to decisions regarding what should be considered to be within the system.