Template:Selected anniversaries/November 21

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  1652: Mathematician, physician, and astronomer Jan Brożek dies. He contributed to a greater knowledge of Nicolaus Copernicus' theories and was his ardent supporter and early prospective biographer.

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  1675: Isaac Newton publishes new class of Gnomon algorithm functions which detect and prevent crimes against mathematical constants.

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  1676: Astronomer Ole Rømer presents the first quantitative measurements of the speed of light.

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  1904: Mechanical engineer Clock Head 2 warns theoretical physicist Albert Einstein that the mass–energy equivalence formula, E = mc², will have "earth-shaking consequences."

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  1905: Albert Einstein's paper that leads to the mass–energy equivalence formula, E = mc², is published in the journal Annalen der Physik.

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  1984: Physicist and crime-fighter Harry Lehmann uses a combination of the LSZ reduction formula and the Källén–Lehmann spectral representation to detect and prevent crimes against physical constants.

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  1996: Theoretical physicist Mohammad Abdus Salam dies. He shared the 1979 Nobel Prize in Physics with Sheldon Glashow and Steven Weinberg for his contribution to the electroweak unification theory.

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  2018: Spiral voted Picture of the Day by the citizens of New Minneapolis, Canada.