Berlin: Julius Springer, 1921. 1st Edition. FIRST EDITIONS OF TWO EARLY PAPERS RELATED TO THE STERN-GERLACH EXPERIMENT, the first describing Stern’s early design of the experiment; the second describing the early results. These papers precede the 1922 publication of “the first demonstration that elementary particles have quantized intrinsic angular momentum distinct from the orbital angular momentum created by their movement within the atom” (History of Physics: The Wenner Collection). Commonly referred to as the Stern-Gerlach experiment, it is one of the most famous in the history of physics.
German physicist Otto Stern (1888–1969) was interested in Sommerfeld’s theory of spatial quantization, specifically, the idea that “the plane in which an electron orbits an atom can have only certain discrete orientations in space” (Brandt, Harvest of the Century, 123). “The concept of “space quantization” (the quantization of angular momentum) was introduced… by Bohr and Sommerfeld in relation to the Bohr model of the atom (described elsewhere), but no one had demonstrated its existence, and some physicists even considered it to be nothing more than a mathematical tool” (Wenner).
Early in 1921, Stern proposed an experiment to test Sommerfeld’s theory. In a paper entitled “Ein Weg zur experimentellen Pruefung der Richtungsquantelung im Magnetfeld”, the first offered here, Stern described his design of an experiment to measure the deflection of silver atoms and demonstrate the quantization of angular momentum. Though seemingly simple in principle, “the experiment was ambitious in practice” (Brandt, 124). “The main experimental problems were mechanical precision (the deflection in the field was only about 0.1mm) and reliable vacuum (the mercury pumps, made of glass, tended to break)” (ibid, 125).
In November of the same year, 1921, and after having brought on board Walther Gerlach from the Institute of Experimental Physics, Stern and Gerlach observed a broadening of the beam and reported it in ‘Der experimentelle Nachweis des magnetischen Moments des Silberatoms,’ the paper offered here. The size of the beam “increased from 0.1 mm to about 0.3 mm if the field was turned on. This result proved that silver atoms possess a magnetic moment.
“With a still better collimated beam in February 1922 the splitting of the beam into two was observed. Spatial quantization was established” (Brandt, pp. 124-126). Item #985
CONDITION & DETAILS: Berlin: Julius Springer. 4to. (9 x 6.5 inches; 225 x 163mm). Two volumes bound as one (Volume 8 precedes Volume 7 in this binding). Solidly bound blue buckram, slight rubbing at the edge tips. Occasional toning within, otherwise very good.