Hi, guys..This is my first time to post. and I gotta aplogize for my bad English..I`m a novice..;;(adsbygoogle = window.adsbygoogle || []).push({});

anyway..here`s my curiosity..

From Paul Dirac`s Principles of Quantum Mechanics..p.153

(section of Motion in a central field of force)

It says that

The angular momentumLof the ptl about the orgin ..and its magnitude L^2 commute with r and p_r since they are scalars...

It`s not hard to verify that [L, r] = [L, p_r] = 0

(L_x=x*p_y-y*p_x, r=(x^2+y^2+z^2)^(1/2) etc.)

But I just wanna understand the underlying physics..

commutator(Quantum Poisson`s Bracket) with L zero?

Are they concerned with conservation of angular momentum? or else?

:)

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# Commutator with r, p_r and angular momentum

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