Wiktionary
n. 1 (context biology English) law of protection of biodiversity, the environment, and natural resources 2 (context physics English) Any of several laws that hold that some physical property remains constant in a closed system regardless of other changes that take place
Wikipedia
In physics, a conservation law states that a particular measurable property of an isolated physical system does not change as the system evolves over time. Exact conservation laws include conservation of energy, conservation of linear momentum, conservation of angular momentum, and conservation of electric charge. There are also many approximate conservation laws, which apply to such quantities as mass, parity, lepton number, baryon number, strangeness, hypercharge, etc. These quantities are conserved in certain classes of physics processes, but not in all.
A local conservation law is usually expressed mathematically as a continuity equation, a partial differential equation which gives a relation between the amount of the quantity and the "transport" of that quantity. It states that the amount of the conserved quantity at a point or within a volume can only change by the amount of the quantity which flows in or out of the volume.
From Noether's theorem, each conservation law is associated with a symmetry in the underlying physics.
Usage examples of "conservation law".
We assume a kind of inertia, or hysteresis effect, or special conservation law for time travel.
Would it help if I rephrased that, and said that he claims to have found an important new conservation law?
And they have formulated a type of Conservation Law which works in the higher Dimension of the Multiplicity of Histories.
According to a body called the Conservation Law Foundation, the whole of the rail system in northern New England could be restored for $500 million.
But now we think its really recoil, and theres a conservation law involved.
By symmetry, or perhaps because of some interdimensional conservation law, the Magritte doorway had vanished.
Somehow energy differences between stars were compensated for within the transport fields-unless some conservation law that man knew nothing about was in operation.
Whatever agency caused it to relocate may be constrained by some physical conservation law.