ABSTRACT
This chapter provides a treasured episode from the heroic age of atomic physics. It describes the historical context of the experiment, chiefly stemming from the atomic model proposed by Niels Bohr in 1913. The chapter also provides an account accessible to anyone with only vague memories of high-school physics or chemistry. It shows how Otto Stern's interest was whetted by the tantalizing, partial successes and patent failures of Bohr's model when confronted with atomic spectra and magnetism. Stern came to focus on the idea of space quantization. The chapter traces the conception, preparation, vicissitudes, and realization of the Stern-Gerlach experiment. Under Albert Einstein's influence, Stern became interested in light quanta, the nature of atoms, magnetism, and statistical physics. In the apt phrase of Abraham Pais, the weird model concocted by Bohr proved a "triumph over logic." Wolfgang Pauli's appeal to space quantization of atomic magnets has historical significance in that it made his colleagues, including Stern, mindful of the idea.
