Talk:Einstein-de Haas effect

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who wrote this page? why aren't any of the papers linked to freely available to be read?

Does this imply that electrons have a mechanical angular momentum? Special:Contributions/24.80.86.98

I wrote the entry. As for the papers, (1) the Physical Review paper (by Richardson) can be accessed only by those who have either a personal subscription for Physical Review or have a computer account at a university or a research institute (provided that these institutes have a campus subscription for Physical Review); in other cases, one has to pay for it (I have just checked it, it costs 20 US dollars), upon which one can download the text (this is not invariably the case: recently, American Physical Society, which owns Physical Review, has decided to make some landmark papers, published in amongst others Physical Review, freely available to the general public); (2) to my best knowledge, the paper by Einstein and de Haas published by Koninklijke Akademie van Wetenschappen te Amsterdam is freely available to the general public — importantly, the paper is in English; (3) the paper by Frenkel in Soviet Physics Uspekhi can be downloaded under similar conditions as those applying to Physical Review.

As for your other question, electron spin is an angular momentum, however one whose origin is quantum-mechanical (as I indicate in the main text): it is described by an operator whose various components do not commute. The nature of your question (your emphasis on "mechanical") suggests that perhaps you should consult some elementary book on quantum mechanics. In such case, the book by David J. Griffiths (Introduction to Quantum Mechanics) would be a very appropriate choice (Chapter 4, Section 3, gives a brief account of angular momentum in quantum mechanics and Chapter 4, Section 4, introduces spin; in this section it is nicely shown how spin is algebraically related to angular momentum in quantum mechanics: the components of the corresponding operator satisfy the same Lie algebra as the components of the operator that one obtains on quantising the classical angular momentum in accordance with the correspondence principle). My remark that the origin of electron spin is quantum mechanical refers to the fact that the quantum-mechanical operator for electron spin cannot be directly deduced by quantising a classical counterpart (such counterpart does not exist); it can only be introduced through using the Lie algebra satisfied by the components of the quantum-mechanical angular momentum operator as the starting point.

Kind regards, --BF 08:09, 31 December 2007 (UTC)