Braunschweig: Friedr. Vieweg & Sohn, 1915. 1st Edition. FIRST EDITION, FULL BOUND VOLUME, OF THE EINSTEIN-DE HAAS EFFECT -- an experimental observation that illustrates the relationship between magnetism and angular momentum and in which a change in the magnetic moment causes the rotation of a free body. In this 1915 paper, Albert Einstein and Wander de Haas report that changing the magnetization of a suspended iron rod by applying an external magnetic field leads to mechanical rotation of the rod – a result that still stands as a textbook illustration of the relationship between magnetism and angular momentum. Papers by Planck (The Quantum Hypothesis for Molecules with Multiple Degrees of Freedom), von Laue, Warburg, Siegbahn, and Born are also present.
Einstein had long contemplated Ampère's 1820 conjecture that magnetism is caused by the microscopic circular motions of electric charges. In light of this [Einstein and de Haas] devised an experiment to test not just Ampère’s hypothesis, but also “Lorentz’s theory that the rotating particles are electrons. The aim of the experiment was to measure the torque generated by a reversal of the magnetization of an iron cylinder” (Calaprice, Einstein Almanac, 52).
In the experiment Einstein and de Haas designed, “a magnetic material [was] suspended with the aid of a thin string inside a magnetic field coil. When the magnetic field [was] increased by the application of an electric current through the field coil, the magnetic material is magnetized. In order to keep the total magnetic moment of the magnetic material constant, the latter rotates. This classical Einstein-de Haas effect demonstrates that the spin angular momentum is of the same nature as the angular momentum of rotating bodies as conceived in classical mechanics” (Ganzhorn, Nature Communications 7, 11443, 2016).
Einstein spoke enthusiastically of the experimental results he and de Haas has achieved, stating that they had "given firm proof of the existence of Ampère's molecular currents" (Pais, Subtle is the Lord, 245).
ALSO INCLUDED: Papers by Planck "Die Quantenhypotese für Molekeln mit mehreren Freiheitsgraden" and "Bemerkung über die Entropiekonstante zweiatomiger Gase", as well as a paper by von Laue "Die Einsteinischen Energieschwankungen" Item #1200
CONDITION & DETAILS: Braunschweig: Friedr. Vieweg & Sohn. 8vo. Unobtrusive stamp on front paste down and title page. In-text figures throughout. Tightly bound in leather over marbled paper boards; gilt-lettered and tooled at the slightly faded spine. Unusually beautiful marbled paper edges. Bright and very clean throughout. Near fine.