Is Angular Momentum Always Conserved with a Rotation-Invariant Lagrangian?

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SUMMARY

Angular momentum is conserved when the Lagrangian is invariant under rotations, as established by Noether's theorem. This conservation law applies broadly, but it is essential to verify the conditions for infinitesimal rotations to ensure the invariance holds in all cases. The discussion confirms that while the theorem provides a general framework, specific scenarios may impose additional restrictions that need to be examined.

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quasar987
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I have this question here from last year's exam that goes

"Use Noether's theorem to show that the angular momentum is conserved when the lagrangian is invariant under rotations."

I just want to know if this is true in the most general case, or if there are some restrictions somewhere not mentioned in the question.

Thank you.
 
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Yes, you'd have to check for infinitesimal rotations.
 

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