An Etymological Dictionary of Astronomy and Astrophysics
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The act or an instance of conserving.

Verbal noun of → conserve.

A general statement that a → physical quantity, such as → energy, → mass, → momentum, or → electric charge is unchanged in an → interaction occurring within a → closed system. See also:
→ conservation of charge, → conservation of energy, → conservation of mass, → conservation of mass and energy, → conservation of matter, → conservation of momentum, → conservation of probability, → parity conservation, → conservative field.

→ conservation; → law.

In any given → frame of reference, → electric charge is neither created nor destroyed. This → law must not be confused with → charge invariance.

→ conservation; → charge.

The → principle whereby the → total energy of a → closed system remains → constant. This means that energy can neither be created nor destroyed. See also the → first law of thermodynamics.

→ conservation; → energy.

A → principle of → classical physics whereby → matter can be neither created nor destroyed. Matter can, however, be → converted into → energy, as predicated by the theory of → special relativity. Also called → conservation of matter.

→ conservation; → mass.

A principle, resulting from Einstein's theory of → special relativity whereby in any → closed system the sum of mass and energy remains → constant.

→ conservation; → mass; → energy.

Same as → conservation of mass.

→ conservation; → matter.

A fundamental law of physics which states that the momentum of a → physical system does not change in the course of time if there are no external forces acting on the system. It is embodied in → Newton's first law. This principle shows that the interaction of bodies composing a → closed system leads only to an exchange in momentum between the bodies but does not affect the motion of the system as a whole. More specifically, interactions between the composing bodies do not change the velocity of the system's → center of mass.

→ conservation; → momentum.

A principle according to which the sum of probabilities of all possible states that might come out of an initial state equals the probability of the initial state.

→ conservation; → probability.

In quantum mechanics, the condition of parity in strong and electrodynamic interactions, where it remains constant and does not change with time. In other words, parity conservation implies that Nature is symmetrical and makes no distinction between right- and left-handed rotations or between opposite sides of a subatomic particle. Thus, for example, two similar radioactive particles spinning in opposite directions about a vertical axis should emit their decay products with the same intensity upward and downward. Same as → parity symmetry.

→ parity; → conservation.