Template:Selected anniversaries/April 20: Difference between revisions

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||1745 – Philippe Pinel, French physician and psychiatrist (d. 1826)
||1745 – Philippe Pinel, French physician and psychiatrist (d. 1826)


File:Johann Friedrich Pfaff.jpg|link=Johann Friedrich Pfaff (nonfiction)|1808: Mathematician and crime-fighter [[Johann Friedrich Pfaff (nonfiction)|Johann Friedrich Pfaff]] publishes new theory of differential forms which quickly finds application in the detection and prevention of [[crimes against mathematical constants]].
File:Johann Friedrich Pfaff.jpg|link=Johann Friedrich Pfaff (nonfiction)|1790: Mathematician and detective [[Johann Friedrich Pfaff (nonfiction)|Johann Friedrich Pfaff]] uses partial differential equations of the first order Pfaffian systems to track and erase the [[Forbidden Ratio]].


||James David Forbes FRS FRSE FGS (b. 20 April 1809) was a Scottish physicist and glaciologist who worked extensively on the conduction of heat and seismology. He invented the seismometer.
||James David Forbes (b. 20 April 1809) was a Scottish physicist and glaciologist who worked extensively on the conduction of heat and seismology. He invented the seismometer.


||1831 – John Abernethy, English surgeon and anatomist (b. 1764)
||1831 – John Abernethy, English surgeon and anatomist (b. 1764)
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||1865 – Astronomer Angelo Secchi demonstrates the Secchi disk, which measures water clarity, aboard Pope Pius IX's yacht, the L'Immaculata Concezion.
||1865 – Astronomer Angelo Secchi demonstrates the Secchi disk, which measures water clarity, aboard Pope Pius IX's yacht, the L'Immaculata Concezion.


||1902 – Pierre and Marie Curie refine radium chloride.
File:Curie_and_radium_by_Castaigne.jpg|link=Radium (nonfiction)|1902: Pierre and Marie Curie refine [[Radium (nonfiction)|radium chloride]].


||Kai Manne Börje Siegbahn (b. 20 April 1918) was a Swedish physicist.
||Kai Manne Börje Siegbahn (b. 20 April 1918) was a Swedish physicist.
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File:Giuseppe Peano.jpg|link=Giuseppe Peano (nonfiction)|1932: Mathematician [[Giuseppe Peano (nonfiction)|Giuseppe Peano]] dies. He did pioneering work in mathematical logic and [[Set theory (nonfiction)|set theory]].
File:Giuseppe Peano.jpg|link=Giuseppe Peano (nonfiction)|1932: Mathematician [[Giuseppe Peano (nonfiction)|Giuseppe Peano]] dies. He did pioneering work in mathematical logic and [[Set theory (nonfiction)|set theory]].


File:Exponential-growth-diagram.svg|link=Crimes against mathematical constants|1932: New class of [[crimes against mathematical constants]] exploits death of mathematician [[Giuseppe Peano (nonfiction)|Giuseppe Peano]].
|File:Exponential-growth-diagram.svg|link=Crimes against mathematical constants|1932: New class of [[crimes against mathematical constants]] exploits death of mathematician [[Giuseppe Peano (nonfiction)|Giuseppe Peano]].


||1945 – Twenty Jewish children used in medical experiments at Neuengamme are killed in the basement of the Bullenhuser Damm school.
||1945 – Twenty Jewish children used in medical experiments at Neuengamme are killed in the basement of the Bullenhuser Damm school.


||Georg Feigl (d. 20 April 1945) was a German mathematician.
File:Georg_Feigl.jpg|link=Georg Feigl (nonfiction)|Mathematician [[Georg Feigl (nonfiction)|Georg Feigl]] dies. He worked on the foundations of geometry and topology, studying fixed point theorems for ''n''-dimensional manifolds. Feigl was one of the initial authors of the Mathematisches Wörterbuch ("Mathematical dictionary").


||Konrad Hermann Theodor Knopp (d. 1957) was a German mathematician who worked on generalized limits and complex functions.
||Konrad Hermann Theodor Knopp (d. 1957) was a German mathematician who worked on generalized limits and complex functions.

Revision as of 19:55, 19 April 2018

  • 1548: Mathematician, astronomer, and alleged time-traveller Petrus Apianus publishes Cosmographicus furatis, his magisterial treatise on crimes against astronomical constants.

    1548: Mathematician, astronomer, and alleged time-traveller Petrus Apianus publishes Cosmographicus furatis, his magisterial treatise on crimes against astronomical constants.

  • 1653: Oliver Cromwell dissolves the Rump Parliament.

    1653: Oliver Cromwell dissolves the Rump Parliament.

  • 1790: Mathematician and detective Johann Friedrich Pfaff uses partial differential equations of the first order Pfaffian systems to track and erase the Forbidden Ratio.

    1790: Mathematician and detective Johann Friedrich Pfaff uses partial differential equations of the first order Pfaffian systems to track and erase the Forbidden Ratio.

  • 1902: Pierre and Marie Curie refine radium chloride.

    1902: Pierre and Marie Curie refine radium chloride.

  • 1932: Mathematician Giuseppe Peano dies. He did pioneering work in mathematical logic and set theory.

    1932: Mathematician Giuseppe Peano dies. He did pioneering work in mathematical logic and set theory.

  • Mathematician Georg Feigl dies. He worked on the foundations of geometry and topology, studying fixed point theorems for n-dimensional manifolds. Feigl was one of the initial authors of the Mathematisches Wörterbuch ("Mathematical dictionary").

    Mathematician Georg Feigl dies. He worked on the foundations of geometry and topology, studying fixed point theorems for n-dimensional manifolds. Feigl was one of the initial authors of the Mathematisches Wörterbuch ("Mathematical dictionary").

  • 1961: Failure of the Bay of Pigs Invasion of US-backed Cuban exiles against Cuba.

    1961: Failure of the Bay of Pigs Invasion of US-backed Cuban exiles against Cuba.

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