Hugo Tetrode
Hugo Martin Tetrode was a Dutch theoretical physicist who contributed to statistical physics, early quantum theory and quantum mechanics.
In 1912, Tetrode developed the Sackur–Tetrode equation, a quantum mechanical expression of the entropy of an ideal gas. Otto Sackur derived this equation independently around the same time. The Sackur–Tetrode constant, S0/R, is a fundamental physical constant representing the translational contribution to the entropy of an ideal gas at a temperature of 1 K and pressure of 100 kPa, where R is the gas constant.
From Amsterdam, Tetrode corresponded with Albert Einstein, Hendrik Lorentz and Paul Ehrenfest on quantum mechanics and wrote several influential papers on quantum mechanics which were published in the German physics journal Zeitschrift für Physik.
In, he proposed that electromagnetic interactions are direct, time-symmetric actions between particles along lightlike intervals, not mediated by independent fields. An isolated charge does not radiate, because radiation is an interaction between an emitting particle and an absorbing particle. As an example, he suggested that if the sun were the only object in the universe, then it will not radiate. Mathematically, this corresponds to using the symmetric Green function for the interaction. Later, Wheeler and Feynman followed his idea in the Wheeler–Feynman time-symmetric theory.
The sun would not radiate if it were alone in space and no other bodies could absorb its radiation.... If for example I observed through my telescope yesterday evening that star which let us say is 100 light years away, then not only did I know that the light which it allowed to reach my eye was emitted 100 years ago, but also the star or individual atoms of it knew already 100 years ago that I, who then did not even exist, would view it yesterday evening at such and such a time.... One might accordingly adopt the opinion that the amount of material in the universe determines the rate of emission. Still this is not necessarily so, for two competing absorption centers will not collaborate but will presumably interfere with each other. If only the amount of matter is great enough and is distributed to some extent in all directions, further additions to it may well be without influence.In 1928, he published two papers on mathematical extensions to Dirac's quantum theory.
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Life
Hugo Tetrode was a member of the rich, prominent Tetrode family. He was the oldest of the three children of Pieter Johan Conrad Tetrode, who served as director of De Nederlandsche Bank from 1919 to 1934. Tetrode was born in what was then Nieuwer-Amstel, at an address that is now part of Amsterdam; as a child he lived on two of Amsterdam's canals. He had a sister Helena Maria, and a younger brother, Pieter.Tetrode left for Germany in 1911 to study mathematics, physics and chemistry at the University of Leipzig, but returned to Amsterdam a year later. In 1912, at the age of 17, he published his first research paper in the German physics journal Annalen der Physik. He published a total of six scientific papers, all on topics of statistical physics and quantum mechanics.
He corresponded with Lorentz and Ehrenfest. His ill-health prevented him from contact with the community. He led a withdrawn life; it is said that when Einstein and Ehrenfest tried to visit him in Amsterdam, Tetrode's maid sent them away: Meneer ontvangt niet. As he neared the end of his life, he became increasingly reclusive, until only his sister would contact him.
Tetrode died at the age of 35, unmarried, after contracting tuberculosis. His sister donated his books to the Zeemanlaboratorium.
Pauli commented to Casimir that, "You have some strange owls in the Netherlands. There's Tetrode, for example. He's done excellent work, but nobody knows him, and he doesn't seem to want to know anyone."