Conservation law

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For the legal aspects of environmental conservation, see environmental law and conservation movement.

In physics, a conservation law states that a particular measurable property of an isolated physical system does not change as the system evolves.

One particularly important physical result concerning laws of conservation is Noether's theorem, which states that there is a one-to-one correspondence between laws of conservation and differentiable symmetries of physical systems. For example, the conservation of energy follows from the time-invariance of physical systems, and the fact that physical systems behave the same regardless of how they are oriented in space gives rise to the conservation of angular momentum.

Exact laws[edit]

A partial listing of physical laws of conservation that are said to be exact laws, or more precisely have never been [proven to be] violated:

Approximate laws[edit]

There are also approximate conservation laws. These are approximately true in particular situations, such as low speeds, short time scales, or certain interactions.

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