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One particularly important physical result concerning conservation laws is Noether's theorem, which states that there is a one-to-one correspondence between conservation laws 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.
A partial listing of conservation laws that are said to be exact laws, or more precisely have never been [proven to be] violated:
There are also approximate conservation laws. These are approximately true in particular situations, such as low speeds, short time scales, or certain interactions.