On This Day
1791 – Long-distance communication speeds up with the unveiling of a semaphore machine in Paris.
A semaphore telegraph is a system of conveying information by means of visual signals, using towers with pivoting shutters, also known as blades or paddles. Information is encoded by the position of the mechanical elements; it is read when the shutter is in a fixed position. The most widely used system was invented in 1792 in France by Claude Chappe, and was popular in the late eighteenth to early nineteenth centuries. Lines of relay towers with a semaphore rig at the top were built within line-of-sight of each other, at separations of 5 to 20 miles. Operators at each tower would watch the neighboring tower through a spyglass, and when the semaphore arms began to move spelling out a message, they would pass the message on to the next tower. This system was much faster than post riders for conveying a message over long distances, and also had cheaper long-term operating costs, once constructed. Semaphore lines were a precursor of the electrical telegraph, which would replace them half a century later, and would also be cheaper, faster, and more private. The line-of-sight distance between relay stations was limited by geography and weather, and prevented the optical telegraph from crossing wide expanses of water, unless a convenient island could be used for a relay station. Modern derivatives of the semaphore system include flag semaphore (a flag relay system) and the heliograph (optical telegraphy using mirror-directed sunlight reflections).
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Born On This Day
1901 – Grete Hermann, German mathematician and philosopher (d. 1984)
Grete (Henry-)Hermann (March 2, 1901 – April 15, 1984) was a German mathematician and philosopher noted for her work in mathematics, physics, philosophy and education. She is noted for her early philosophical work on the foundations of quantum mechanics, and is now known most of all for an early, but long-ignored critique of a no-hidden-variable theorem by John von Neumann. It has been suggested that, had her critique not remained nearly unknown for decades, the historical development of quantum mechanics might have been very different.
Hermann studied mathematics at Göttingen under Emmy Noether, where she achieved her Ph.D. in 1926. Her doctoral thesis, “Die Frage der endlich vielen Schritte in der Theorie der Polynomideale” (in English “The Question of Finitely Many Steps in Polynomial Ideal Theory”), published in Mathematische Annalen, is the foundational paper for computer algebra. It first established the existence of algorithms (including complexity bounds) for many of the basic problems of abstract algebra, such as ideal membership for polynomial rings. Hermann’s algorithm for primary decomposition is still in contemporary use.
Assistant to Leonard Nelson
From 1925 to 1927, Hermann worked as assistant for Leonard Nelson. Together with Minna Specht, she posthumously published Nelson’s work System der philosophischen Ethik und Pädagogik, while continuing her own research.
As a philosopher, Hermann had a particular interest in the foundations of physics. In 1934, she went to Leipzig “for the express purpose of reconciling a neo-Kantian conception of causality with the new quantum mechanics”. In Leipzig, many exchanges of thoughts took place among Hermann, Carl Friedrich von Weizsäcker, and Werner Heisenberg. The contents of her work in this time, including a focus on a distinction of predictability and causality, are known from three of her own publications, and from later description of their discussions by von Weizsäcker, and the discussion of Hermann’s work in chapter ten of Heisenberg’s The Part and The Whole. From Denmark, she published her work The foundations of quantum mechanics in the philosophy of nature (German original title: Die naturphilosophischen Grundlagen der Quantenmechanik). This work has been referred to as “one of the earliest and best philosophical treatments of the new quantum mechanics”. In this work, she concludes:
The theory of quantum mechanics forces us […] to drop the assumption of the absolute character of knowledge about nature, and to deal with the principle of causality independently of this assumption. Quantum mechanics has therefore not contradicted the law of causality at all, but has clarified it and has removed from it other principles which are not necessarily connected to it.
— Grete Hermann, The foundations of quantum mechanics in the philosophy of nature
In 1935, Hermann published a critique of John von Neumann’s 1932 proof which was widely claimed to show that a hidden variable theory of quantum mechanics was impossible. Hermann’s work on this subject went unnoticed by the physics community until it was independently discovered and published by John Stewart Bell in 1966, and her earlier discovery was pointed out by Max Jammer in 1974. Some have posited that had her critique not remained nearly unknown for decades, the historical development of quantum mechanics may have been greatly affected; in particular, it has been speculated that a wider awareness of her work would have put in question the unequivocal acceptance of the Copenhagen interpretation of quantum mechanics, by providing a credible basis for the further development of nonlocal hidden variable theories. In 2010, Jeffrey Bub published an argument that Bell (and, thus, also Hermann) had misconstrued von Neumann’s proof, claiming that it does not attempt to prove the absolute impossibility of hidden variables, and that it is actually not flawed, after all. The validity of Bub’s argument is, in turn, disputed.
In June 1936, Hermann was awarded the Richard Avenarius prize together with Eduard May and Th. Vogel.
As Adolf Hitler came to power in Germany, Hermann participated in the underground movement against the Nazis. She was member of the Internationaler Sozialistischer Kampfbund (ISK).
Emigration and later years
By 1936, Hermann left Germany for Denmark and later France and England. In London, in order to avoid standing out on account of her German provenance, she married a man called Edward Henry early in 1938. Her prescience was justified by events: two years later the British government invoked its hitherto obscure Regulation 18B of the Defence (General) Regulations 1939, identifying several thousand refugees who had fled Germany for reasons of politics or race as enemy aliens and placing them in internment camps.
After the war ended in 1945 she was able to combine her interests in physics and mathematics with political philosophy. She rejoined the Social Democratic Party (SPD) on returning in 1946 to what would become, in 1949, the German Federal Republic (West Germany). Starting in 1947 she was one of those contributing behind the scenes to the Bad Godesberg Programme, prepared under the leadership of her longstanding ISK comrade Willi Eichler, and issued in 1959, which provided a detailed modernising platform that carried the party into government in the 1960s.
She was nominated professor for philosophy and physics at the Pädagogische Hochschule in Bremen and played a relevant role in the Gewerkschaft Erziehung und Wissenschaft. From 1961 to 1978, she presided over the Philosophisch-Politische Akademie, an organisation founded by Nelson in 1922, oriented towards education, social justice, responsible political action and its philosophical basis.
Grete Hermann: Die naturphilosophischen Grundlagen der Quantenmechanik, Naturwissenschaften, Volume 23, Number 42, 718-721, doi:10.1007/BF01491142 (preview in German language)
Grete Hermann: Die Frage der endlich vielen Schritte in der Theorie der Polynomideale. Unter Benutzung nachgelassener Sätze von K. Hentzelt, Mathematische Annalen, Volume 95, Number 1, 736-788, doi:10.1007/BF01206635 (abstract in German language) — The question of finitely many steps in polynomial ideal theory (review and English-language translation)
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