Centrifugal force is an abstraction, but angular momentum has physical reality at the subatomic level.  See Feynman, chap. 17.[1]  Photons have angular momentum, even though they don&#x27;t have a meaningful size.  This is strange, but it&#x27;s reality.<p>[1] <a href="http:&#x2F;&#x2F;www.feynmanlectures.caltech.edu&#x2F;III_17.html" rel="nofollow">http:&#x2F;&#x2F;www.feynmanlectures.caltech.edu&#x2F;III_17.html</a>