1940s, "Autobiographical Notes" (1949)
Context: Reflections of this type made it clear to me as long ago as shortly after 1900, i. e., shortly after Planck's trailblazing work, that neither mechanics nor electrodynamics could (except in limiting cases) claim exact validity. By and by I despaired of the possibility of discovering the true laws by means of constructive efforts based on known facts. The longer and the more despairingly I tried, the more I came to the conviction that only the discovery of a universal formal principle could lead us to assured results.... How, then, could such a universal principle be found? After ten years of reflection such a principle resulted from a paradox upon which I had already hit at the age of sixteen: If I pursue a beam of light with the velocity c (velocity of light in a vacuum), I should observe such a beam as a spatially oscillatory electromagnetic field at rest. However, there seems to be no such thing, whether on the bases of experience or according to Maxwell's equations. From the very beginning it appeared to me intuitively clear that, judged from the stand-point of such an observer, everything would have to happen according to the same laws as for an observer who, relative to the earth, was at rest.
“A simple calculation shows that from the classical theory follows that we should find a broadening of the beam with the maximum intensity on the place of the beam without field. However, from the quantum theory follows that we should find there no intensity at all, and deflected molecules on both sides. The beam should split up in two beams corresponding to the two orientations of the magnet. The experiment decided in favor of the quantum theory.”
the conclusion of the historical Stern-Gerlach experiment, in The Method of Molecular Rays http://nobelprize.org/nobel_prizes/physics/laureates/1943/stern-lecture.html, Nobel Lecture, December 12, 1946.
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Otto Stern 2
German physicist 1888–1969Related quotes
Source: Dictionary of Burning Words of Brilliant Writers (1895), p. 220
“When did morning ever break,
And find such beaming eyes awake?”
Fly not yet.
Bartlett's Familiar Quotations, 10th ed. (1919)