3 2 2 D O C U M E N T 2 7 5 O C T O B E R 1 9 2 1
[6]“I. Nebenserie” (Sommerfeld 1921b, p. 230).
[7]The structure of triplets (and duplets) in spectra had suggested to Sommerfeld to apply the above
selection principle, familiar for the azimuthal quantum number, also to an inner quantum number with
an unknown geometrical interpretation. He originally believed that this proposal would receive empir-
ical support if the forbidden lines could be made visible in strong electrical fields (Sommerfeld 1920,
pp. 230–234). Friedrich Paschen, together with Ernst Back, observed the forbidden triplet lines in
strong magnetic fields in the spectra of Zn, Ca, and Cd (Paschen and Back 1921, pp. 263–265).
[8]The second to last arrow on the right in Sommerfeld’s diagram should point to level 1.
[9]See Götze 1921; Richard Götze was a student of Friedrich Paschen in Tübingen. His results were
due to an analysis of older data obtained by Johannes R. Rydberg and Sergius Popov (see also Paschen
and Götze 1922, pp. 20–21, and Sommerfeld and Heisenberg 1922, p. 149).
[10]In 1919, Teunis van Lohuizen had suggested that the line splitting of the anomalous Zeeman
effect for multiplets had its origin in a corresponding splitting of multiplet energy levels (Lohuizen
1919). Paschen and Back believed that their experimental results confirmed Alfred Landé’s most
recent rules for the anomalous Zeeman effect (Paschen and Back 1921, p. 265; Landé 1921). How-
ever, Sommerfeld was not favorably inclined toward Landé’s approach (Forman 1970, pp. 235–236).
275. To Michele Besso
[Florence,] 20. X. [1921]
…[1]
Lieber Michele!
Wir sitzen da in Florenz zusammen, wie wenns nichts weiter
wäre.[2]
Morgen
fahre ich mit Albert nach Bologna, wo ich italienisch vortragen soll, die Armen!
Dann fahren wir nach Zürich. Ich sehe Dich so gern; vielleicht komme ich schnell
nach Bern, habe aber wenig Zeit (28. bis 2). Interessantes Experiment über Licht-
emission in Arbeit in
Berlin.[3]
Herzliche Grüsse Dein
Albert
… [4]
AKS. Einstein and Besso 1972, p. 170. [75 030.1]. The card is addressed “Ing. M. A. Besso Zieglerstr.
42 Bern Svizzera,” and postmarked “Firenze Ferrovia 20–21 20 X 1921.” The verso of the card repro-
duces the Pillars of Palazzo Vecchio.
[1]Greetings in Beatrice Rusconi-Besso’s hand are omitted.
[2]Einstein mentioned his visit with Maja Winteler-Einstein in Doc. 260.
[3]On this experiment, see Doc. 261.
[4]Paul Winteler and Maja Winteler-Einstein’s greetings and signatures are omitted.
Linse
K
an
al
s
t
.
Lichtstrahl gekrümmt
nach Undulationstheorie
Schwefelkohlenst.