= Walter Schottky
{c}
{tag=Physicist}
{title2=1886–1976}
= W. Schottky
{c}
{synonym}
<Walter Schottky> explained a fundamental source of electrical noise: even a steady mean <electric current> can fluctuate because charge arrives in discrete units. His 1918 paper studies intrinsic limits to detecting weak signals with amplifying tubes, distinguishing charge discreteness from thermal motion. For independent charge-transfer events, the modern <shot noise> relation is $S_I=2eI$ for the one-sided current-noise <power spectral density>. Its dependence on the mean current $I$ makes the noise a probe of charge-transfer statistics, rather than merely a defect of an amplifier.<Über spontane Stromschwankungen in verschiedenen Elektrizitätsleitern by Walter Schottky>[Annalen der Physik 57, 541–567 (1918), introduction and charge-discreteness contribution]{ref}
A <physicist> who held a theoretical-physics professorship at Rostock from 1923 to 1927.<Walter Schottky by Stiftung Werner-von-Siemens-Ring>[Werdegang: professor of theoretical physics at Rostock, 1923–1927; subsequent Siemens research]{ref}
\Image[https://upload.wikimedia.org/wikipedia/commons/4/4a/Walter_Hermann_Schottky_%281886-1976%29.jpg]
{title=Portrait of <Walter Schottky>}
{source=https://commons.wikimedia.org/wiki/File:Walter_Hermann_Schottky_(1886-1976).jpg}
{width=225}
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