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## Conservation law
In physics, a
- conservation of energy (including mass)
- conservation of mass
- conservation of momentum
- conservation of angular momentum
- conservation of electric charge
- conservation of color-charge
- conservation of magnetic flux
Noether's theorem expresses the equivalence which exists between conservation laws and the invariance of physical laws with respect to certain transformations (typically called "symmetries") (This only applies to systems describable by a Lagrangian). There is an analogous theorem for Hamiltonian mechanics. For instance, time-invariance implies that energy is conserved, translation-invariance implies that momentum is conserved, and rotation-invariance implies that angular momentum is conserved. Some conservation laws hold in many circumstances, but exceptions to them have been observed. Such is the violation of parity conservation; apparently the universe has "handedness" (right versus left). ## Philosophy of Conservation Laws*Things that remain unchanged, in the midst of change*
In fact, quantities that are conserved, | |||||

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