### Favorite funny stories about mathematicians

Below I have collected some of my favorite quotations. I also provide the original references of them.

In 1817, when lecturing before private society in London on the element chlorine, Faraday thus expressed himself with reference to this question of utility. “Before leaving this subject, I will point out the history of this substance as an answer to those who are in the habit of saying to every new fact, ‘What is its use?’ Dr. Franklin says to such, ‘What is the use of an infant?’ The answer of the experimentalist is ‘Endeavour to make it useful’ When Scheel discovered this substance, it appered to have no use; it was in its infancy and useless state, but having grown up to maturity, witness its powers and see what endeavours to make it useful have done.”

[Henry Bence Jones (1813–1873) angol kémikus 1870-ben megjelent The Life and Letters of Faraday könyvének első kötetében a 218. oldalon, valamint John Tyndall (1820–1893) ír fizikus 1868-ban megjelent Faraday as a Discoverer című könyvének 35. oldalán. Érdemes még elolvasni ezt a cikket is, amely részletesen tárgyalja ennek és a következő anekdotának az eredetét.]

The Prime Minister is said to have asked Faraday what use of his discovery of electromagnetism might have. “Soon you will be able to tax it.”

[See page xxxi of the book Democracy and Liberty written by William Edward Hartpole Lecky (1838–1903).]

In Cambridge, they tell the following story about Maxwell: Maxwell was lecturing and, seeing a student dozing off, awakened him, asking, “Young man, what is electricity?” “I'm terribly sorry, sir,” the student replied, “I knew the answer but I have forgotten it.” Maxwell’s response to the class was, “Gentlemen, you have just witnessed the greatest tragedy in the history of science. The one person who knew what electricity is has forgotten it.”

[See pages 55– of the nice book Random Walks and Electric Networks written by Peter G. Doyle and J. Laurie Snell.]

Once when lecturing in class Lord Kelvin used the word “mathematician” and then interrupting himself asked his class: “Do you know what a mathematician is?” Stepping to his blackboard he wrote upon it: integral from minus infinity to plus infinity of exp(-x^2)dx = sqrt(pi). Then putting his finger on what he had written, he turned to his class and said, “a mathematician is one to whom that is as obvious as that twice two makes four is to you. Liouville was a mathematician” Then he resumed his lecture.

[See Volume 2, page 1139 of the book the book The Life of William Thomson Baron Kelvin of Largs written by Silvanus Phillips Thomson (1851–1916).]

In 1916, in Kraków's Planty gardens, Banach encountered Professor Hugo Steinhaus, one of the renowned mathematicians of the time. According to Steinhaus, while he was strolling through the gardens he was surprised to overhear the term “Lebesgue measure” (Lebesgue integration was at the time still a fairly new idea in mathematics) and walked over to investigate. As a result he met Banach, as well as Otto Nikodym and Wilkosz. Steinhaus became fascinated with the self-taught young mathematician. The encounter resulted in a long-lasting collaboration and friendship. In fact, soon after the encounter Steinhaus invited Banach to solve some problems he had been working on but which had proven difficult. Banach solved them within a week and the two soon published their first joint work (On the Mean Convergence of Fourier Series). Steinhaus, Banach and Nikodym, along with several other Kraków mathematicians (Władysław Ślebodziński, Leon Chwistek, Jan Kroć, and Włodzimierz Stożek) also established a mathematical society, which eventually became the Polish Mathematical Society. The society was officially founded on April 2, 1919. It was also through Steinhaus that Banach met his future wife, Łucja Braus.

[See Wikipedia. Other sources mention only Nikodym with whom Banach was talking about Lebesgue integral.]

There is a story that emanates from the high table at Trinity that is instructive in this regard. G. H. Hardy, the pure mathematician—to whom I owe all that I know of pure mathematics—remarked on this remarkable fact, and some-one took him up from across the table and said, Do you mean, Hardy, if I said that two and two make five that you could prove any other proposition you like?'' Hardy said, Yes, I think so.'' Well, then, prove that McTaggart is the Pope.'' Well,'' said Hardy, if two and two make five, then five is equal to four. If you subtract three, you will find that two is equal to one. McTaggart and the Pope are two; therefore, McTaggart and the Pope are one.'' I gather it came rather quickly.

[Quoted by Ronald Aylmer Fisher in his 1958 paper című The nature of probability.]