## Saturday 18 May 2024

### On This Day in Math - May 18

I've dealt with numbers all my life, of course, and after a while you begin to feel that each number has a personality of its own.  A twelve is very different from a thirteen, for example.  Twelve is upright, conscientious, intelligent, whereas thirteen is a loner, a shady character who won't think twice about breaking the law to get what he wants.  Eleven is tough, an outdoorsman who likes tramping through woods and scaling mountains; ten is rather simpleminded, a bland figure who always does what he's told; nine is deep and mystical, a Buddha of contemplation....

~Paul Auster, The Music of Chance

The 138th day of the  year; 138 is a sphenic number(the product of three primes from the Greek for "wedge shaped") and is the smallest product of 3 primes, such that in base 10, the third prime is a concatenation of the other two: (2)(3)(23)

138 is the sum of four consecutive primes (29 + 31 + 37 + 41),

138 is a palindrome in base 8 (212)

138 is a congruent number, it is the area of a right triangle with all sides rational.

and 138 can be written in palindromic expression, 138 = 19+2*7*2+91 *@AmbrigrammDesign.

138 is an Ulam Number, a member of the sequence created by a sieve process by Stan Ulam in 1964.  It begins with the numbers 1, 2, and then each successive term is the smallest larger number that is the sum of two distinct numbers in the sequence, in a single way.  The first few numbers are 1, 2, 3, 4, 6, 8, 11,,, Five is missing because its sum can be created in two different ways, 2+3 or 1+4.

See more math facts at Math Day of the Year Facts

EVENTS

1618 Kepler, On how he discovered his Third law:
...and if you want the exact moment in time, it was conceived mentally on 8th March in this year one thousand six hundred an eighteen, but submitted to calculation in an unlucky way, and therefore rejected as false, and finally returning on the 15th of May and adopting a new line of attack, stormed the darkness of my mind. So strong was the support from the combination of my labor of seventeen years on the observations of Brahe and the present study, which conspired together, that at first I believed I was dreaming, and assuming my conclusion among my basic premises. But it is absolutely certain and exact that the proportion between the periodic times of any two planets is precisely the sesquialterate proportion of their mean distances ...
* Harmonice mundi (Linz, 1619) Book 5, Chapter 3, trans. Aiton, Duncan and Field, p. 411.

", as Kepler later recalled, on the 8th of March in the year 1618, something marvelous "appeared in my head". He suddenly realized that

III.  The proportion between the periodic times of any two planets is precisely one and a half times the proportion of the mean distances.

Presumably he used the word “proportion” here to signify the logarithm of the ratio, so he is asserting that log(T1/T2) = (3/2)log(r1/r2), where Tj are the periods and rj are the mean radii of the orbits of any two planets. In the form of a diagram, his insight looks like this:

At first it may seem surprising that it took a mathematically insightful man like Kepler over twelve years of intensive study to notice this simple linear relationship between the logarithms of the orbital periods and radii. In modern data analysis the log-log plot is a standard format for analyzing physical data. However, we should remember that logarithmic scales had not yet been invented in 1605. A more interesting question is why, after twelve years of struggle, this way of viewing the data suddenly "appeared in his head" early in 1618. (Kepler made some errors in the calculations in March, and decided the data didn't fit, but two months later, on May 15 the idea "came into his head" again, and this time he got the computations right, and thought he was dreaming because the fit is so exact.)

Is it just coincidental that John Napier's "Mirifici Logarithmorum Canonis Descripto" (published in 1614) was first seen by Kepler towards the end of the year 1616? We know that Kepler was immediately enthusiastic about logarithms, which is not surprising, considering the masses of computation involved in preparing the Rudolphine Tables. Indeed, he even wrote a book of his own on the subject in 1621. It's also interesting that Kepler initially described his "Third Law" in terms of a 1.5 ratio of proportions, exactly as it would appear in a log-log plot, rather than in the more familiar terms of squared periods and cubed distances. It seems as if a purely mathematical invention, namely logarithms, whose intent was simply to ease the burden of manual arithmetical computations, may have led directly to the discovery/formulation of an important physical law, i.e., Kepler's third law of planetary motion. (Ironically, Kepler's academic mentor, Michael Maestlin, chided him − perhaps in jest? − for even taking an interest in logarithms, remarking that "it is not seemly for a professor of mathematics to be childishly pleased about any shortening of the calculations".) By the 18th of May, 1618, Kepler had fully grasped the logarithmic pattern in the planetary orbits: 'Now, because 18 months ago the first dawn, three months ago the broad daylight, but a very few days ago the full Sun of a most highly remarkable spectacle has risen, nothing holds me back.' "

*mathpages.com

1772 Euler shows that

in paper to St. Petersburg Academy (dates in Russia at this time were still on Julian Calendar)
This value, which Euler approximated to 16 decimal places, 1.2020569031595942, is named Apery'a constant after Roger Apéry, who proved in 1978 that it is irrational. No other odd Zeta(n) has been proven either rational or irrational. It is still not known if it is transcendental. *Wik
1787, Joseph-Louis Lagrange left Berlin to become a member of the Académie des Sciences in Paris, where he remained for the rest of his career. He had worked in Berlin for more than 20 years.   He made significant contributions to the fields of analysis, number theory, and both classical and celestial mechanics.

1825 Faraday isolates benzine. In 1825, Faraday started work on a sample of oil that had been sent to him for analysis by the Portable Oil Company of London. He subjected this oil to fractional distillation, a process that proved to be extremely difficult, and it took him some time to resolve the oil into its pure components. By repeated fractional distillation followed by selective fractional freezing, each stage monitored by analysis, he produced a fairly pure sample of what he called bicarburet of hydrogen. Faraday’s notebook records these procedures, which he carried out on 18 and 19 May 1825. Auguste Laurent suggested the name benzene. *Jennifer Wilson, Celebrating Michael Faraday’s Discovery of Benzene, Ambix,Volume 59, Issue 3

1852 Massachusetts becomes the ﬁrst state to pass a compulsory attendance law for school children. *VFR

1896, the Supreme Court ruled separate-but-equal facilities constitutional on intrastate railroads. For some fifty years, the Plessy v. Ferguson decision upheld the principle of racial segregation. Across the country, laws mandated separate accommodations on buses and trains, and in hotels, theaters, and schools.
In a speech delivered in the Ohio House of Representatives in 1886 and later published as The Black Laws, legislator Benjamin W. Arnett described life in segregated Ohio:

"This foe of my race stands at the school house door and separates the children, by reason of 'color,' and denies to those who have a visible admixture of African blood in them the blessings of a graded school and equal privileges... We call upon all friends of 'Equal Rights' to assist in this struggle to secure the blessings of untrammeled liberty for ourselves and posterity. "
After hearing arguments by NAACP lawyer Thurgood Marshall, the Supreme Court overruled the Plessy decision on May 17, 1954. In Brown v. the Board of Education, a unanimous Court adopted Justice Harlan's position that segregation violated the Thirteenth and Fourteenth Amendments to the Constitution. *Library of  Congress
Marshall (center), George Edward Chalmer Hayes, and James Nabrit congratulate one another after the Supreme Court's decision in Brown v. Board of Education.

1901 Charles Sanders Peirce writes George A. Plimpton,  head of Ginn and Company and famous collector of rare mathematical books, describing what the contents of a newly acquired book must be were it indeed the great Liber Abaci (1202) of Fibonacci. In 1949 Carolyn Eisele’s discovery of this letter—still tucked into the back cover of the volume—began her career as a Peirce scholar. [HM 9, 335] *VFR (I have been advised by Adam Shapiro that Plimpton was not head of Ginn & Co until the death of Edwin Ginn in 1914.)
As a student at Columbia University, Eisele took a course in the history of mathematics from David Eugene Smith, but her professional contributions to the subject began in 1947, when she took a sabbatical to prepare for a course in the history of mathematics that she had been asked to teach at Hunter College. While working in the George Arthur Plimpton collection at the Columbia University library, she found the manuscript .
Caroline Eisele was an American mathematician and historian of mathematics.

In 1910, Halley's Comet was visible from Earth, moving across the face of the sun. *TIS
1910 Halley's comet was big news during its visible period in New York City. Beginning with the Saturday edition of May 14 and continuing on through the Sunday edition of May 22, the comet was given top billing in the New York Times. This was the period when the comet was at the height of its brilliance and activity and the coverage clearly reflected this.
May 18: Earth to pass through come tail for 6 hours; C.B. Harmon invites college deans to join him in viewing comet from balloon. *Joseph M. Laufer, Halley's Comet Society - USA

Colonel Clifford B. Harmon, an early balloonist and aviator, established international trophies to be awarded annually to the world’s outstanding aviator, aviatrix, aeronaut (balloon or dirigible) and astronaut (added in 1969).

Today, the NAA continues to uphold the tradition by giving out the aeronaut (ballooning) trophy, awarded for the most outstanding international achievement in the art and/or science of aeronautics (ballooning) for the previous year.

1933 John Kieran’s Sports of the Times column in the New York Times is entitled “The Coordinate Clash, or Block that Abscissa.” The column was a humorous analogy between football and the upcoming mathematical contest between Harvard and Army. *VFR

It began with a poem called "A Logarithmic Lilt" which read:

"The Harvard horde is plotting, under cover of the dark, A fight to make the Crimson Chord subtend the Army arc. The Coefficient Corps has drilled with sharpened pencil tips And plans to drive the enemy away from the ellipse. The Harvard cry is 'Break the square and take the cube away!

While at the Point 'Abscissa' is the watchword of the day. And high upon the turret top the sentry turns his head And hears the Cambridge legion come with logarithmic tread. 'Advance and give the cosine!' rings the challenge through the air.

The Crimson host advances-and we hope the fight is fair." Later in the article, Kieran mentions the role of Lieutenant C. P. Nicholas, later head of the Mathematics Department, and Lieutenant Robinson as the Army coaches of the Analytics and Calculus, respectively. Other articles in newspapers continued the football analogy as their headlines read "Army Meets Harvard in Mathematical 'Go'," Squads at West Point Begin Contest in Calculus and Analytic Geometry," and "Harvard and West Point Line up on the Geometry Field."

This was the predecessor of the first national Putnam Competition was a mathematics contest between Harvard and the United States Military Academy from William Lowell Putnam's original idea for academic competition between schools in 1921.  For those who wonder, Army creamed Harvard in the Football game on Nov 5 the previous fall, 42-0; and also won the math contest by a much closer score 112-98.

The members of the West Point team were awarded certificates, medals, and mathematics books. They all wrote personal letters to Mrs. Putnam thanking her for supporting the competition and expressing enthusiasm for more contests. However, with Mr. Lowell's retirement from the position of President of Harvard in 1933 and Mrs. Putnam s fading health (she died in 1935), the Harvard-USMA competition was not repeated.

In 1927, Elizabeth Lowell Putnam (Putnam's wife, and Percivell Lowell's sister) had established the William Lowell Putnam Intercollegiate Memorial Fund in order to begin a college-level mathematics competition, the William Lowell Putnam Mathematical Competition. This contest, which continues to this day, began in 1935 under the direction of the Mathematical Association of America.
Elizabeth Lowell Putnam, reading with her sister, Amy:

1952 Prof. Willard F. Libby determined the age of Stonehenge on Salisbury Plain, England, at about 1848 BC (+/- 275 years) through analysis of the carbon-14 radioisotope in charcoal remains excavated there there. Update of C-14 ceases when plants or animals die, and the proportion in the organic remains steadily declines through radioactive decay. Since the half-life of C-14 is about 5,600 years, measurement of the remaining proportion in dead organic matter, indicates the age of that sample. Astronomer Sir Joseph Norman Lockyer had previously calculated that on Midsummer Day, 1680 BC, the sun rose directly over a special marking notch that can still be seen on the Heel Stone. Libby's measurements support that estimate. *TIS

1969, the Apollo 10 was launched to be a complete staging of the Apollo 11 mission without actually landing on the Moon. The mission was the second to orbit the Moon and the first to travel to the Moon with the entire Apollo spacecraft configuration. It made a successful eight-day dress rehearsal for the first manned moon landing. Astronauts Thomas Stafford and Eugene Cernan descended inside the Lunar Module to within 14 kilometers of the lunar surface (achieving the closest approach to the Moon before Apollo 11 landed two months later). Apollo 10 splashed down at 12:52 pm on 26 May, less than 4 miles (6.4 km) from the target point and the recovery ship
The crew poses with their launch vehicle; left to right, Cernan, Young, Stafford.

1993 A headline in the National Enquirer tabloid mocked the National Science Foundation for funding a study by Georgia Southern Professor Jonathon Copeland to study fireflies in Borneo. "Not a bright Idea." It quoted Wisconsin Republican representative (or mis-representative) as saying he didn't think it was a "bright" idea. Ironically, the same week that the article appeared, an article in Time reported that doctors were using luciferase, the light emitting enzyme of the butterfly, in testing drugs against resistant strains of tuberculosis.*Steven Strogatz, Sync

BIRTHS
1048 Omar Khayyam (18 May, 1048–1131)  (his birthdate is sometimes given as 15 May) Persian poet, mathematician, and astronomer. Khayyam, who was born at Nishapur (now in Iran), produced a work on algebra that was used as a textbook in Persia until this century. In geometry, he studied generalities of Euclid and contributed to the theory of parallel lines. Around 1074, he set up an observatory and led work on compiling astronomical tables, and also contributed to the reform of the Persian calendar. His contributions to other fields of science included developing methods for the accurate determination of specific gravity. He is known to English-speaking readers for his "quatrains" as The Rubáiyát of Omar Khayyám, published in 1859 by Edward Fitzgerald, though it is now regarded as an anthology of which little or nothing may be by Omar. *TIS

"Whoever thinks algebra is a trick in obtaining unknowns has thought it in vain. No attention should be paid to the fact that algebra and geometry are different in appearance. Algebras are geometric facts which are proved by propositions five and six of Book two of Elements."
Omar Khayyam
Omar Khayyam's construction of a solution to the cubic x^3 + 2x = 2x^2 + 2. The intersection point produced by the circle and the hyperbola determine the desired segment.

1610 Stefano della Bella, an Italian artist and engraver, was born May 18, 1610. When della Bella was barely twenty-one years old, he was commissioned to design and etch the frontispiece to Galileo’s Dialogue on the Two Chief World Systems (1632).

1711 Ruggero Giuseppe Boscovich Astronomer and mathematician who gave the first geometric procedure for determining the equator of a rotating planet from three observations of a surface feature and for computing the orbit of a planet from three observations of its position. Boscovich was one of the first in continental Europe to accept Newton's gravitational theories and he wrote 70 papers on optics, astronomy, gravitation, meteorology and trigonometry. Boscovich also showed much ability in dealing with practical problems. He suggested and directed the draining of the Pontine marshes near Rome, and recommended the use of iron bands to control the spread of cracks in the dome of St. Peter's basilica.*TIS  A slightly enlarged description of his life is here

The first page of figures from Theoria Philosophiæ Naturalis from 1763. Figure 1 is the force curve which received so much attention from later natural philosophers such as Joseph Priestley, Humphry Davy, and Michael Faraday. The ordinate is force, with positive values being repulsive, and the abscissa is radial distance. Newton's gravitational attractive force is clearly seen at the far right of figure 1.

1850 Oliver Heaviside (18 May 1850, 3 Feb 1925) English physicist who predicted the existence of the ionosphere. In 1870, he became a telegrapher, but increasing deafness forced him to retire in 1874. He then devoted himself to investigations of electricity. In 1902, Heaviside and Kennelly predicted that there should be an ionised layer in the upper atmosphere that would reflect radio waves. They pointed out that it would be useful for long distance communication, allowing radio signals to travel to distant parts of the earth by bouncing off the underside of this layer. The existence of the layer, now known as the Heaviside layer or the ionosphere, was demonstrated in the 1920s, when radio pulses were transmitted vertically upward and the returning pulses from the reflecting layer were received. *TIS He adapted complex numbers to the study of electrical circuits, invented mathematical techniques to the solution of differential equations (later found to be equivalent to Laplace transforms), reformulated Maxwell's field equations in terms of electric and magnetic forces and energy flux, and independently co-formulated vector analysis. Although at odds with the scientific establishment for most of his life, Heaviside changed the face of mathematics and science for years to come. Among many others, he coined the terms for admittance , conductance , impedance , permeability , and inductance. *Wik
Much later Heaviside was honored in a far more enduring fashion--he became a phrase in an Andrew Lloyd Webber musical. In the climax of Cats the Musical, Grizabella is chosen by Old Deuteronomy to ascend to cat paradise and be reborn, while the feline chorus sings: "Up, up, up, past the Russell Hotel; up, up, up, up to the Heaviside layer" . The Heaviside layer (NOT the Kennelly-Heaviside layer) became for Webber (and Cats) a metaphor for heaven. Linda Hall Org

My favorite Heaviside quote is "Why should I refuse a fine dinner just because I don't understand the digestive processes involved?"
For context on the quote, from Wikipedia: Between 1880 and 1887, Heaviside developed the operational calculus using 𝑝  for the differential operator, (which Boole had previously denoted by 𝐷), giving a method of solving differential equations by direct solution as algebraic equations. This later caused a great deal of controversy, owing to its lack of rigour. He famously said, "Mathematics is an experimental science, and definitions do not come first, but later on. They make themselves, when the nature of the subject has developed itself."  *HT Steve Palzewicz

1853  Albert Badoureau (May 18, 1853, July 20, 1923discovered 37 of the 75 non-prismatic uniform polyhedra in 1878. These were in addition to the 22 known at the time (5 Platonic solids, 13 Archimedean solids, and 4 Kepler-Poinsot polyhedra). He is also famed for his work in geology and for being the mathematical advisor to Jules Verne.
It was at the meetings of the Académie d'Amiens and the Société industrielle d'Amiens that Badoureau met Jules Verne. This resulted in Verne's book Sans dessus dessous Ⓣ (1889) being based on the scientific information supplied by Badoureau. The story involves firing a gigantic cannon to change the axis of rotation of the earth. Badoureau and Verne corresponded about the mathematical details, discussing the size of the cannon, the use of multiple cannons, the force required of the explosive to create the necessary velocity of the cannonball etc. In Verne's story, the mathematician J-T Maston, is distracted and confuses metres and kilometres in the value of the earth's radius with predictable results! We cannot help thinking how Verne anticipated how the Americans lost the Mars Climate Orbiter in September 1999 (at a loss of \$125 million) because the Jet Propulsion Laboratory used metric units and Lockheed Martin Astronautics, who designed and built the spacecraft, used Imperial units. Returning to Sans dessus dessous Ⓣ we note that one of the main characters, Alcide Pierdeux, is a slightly fictionalised version of Badoureau himself. Badoureau seemed quite happy with this for often when writing to Verne he signed his letters "Alcide Pierdeux."*SAU

1859 Harry Fielding Reid (18 May 1859; 18 Jun 1944 at age 85) who introduced the term elastic rebound in a report (1910) on the 1906 San Francisco earthquake. His early career was as a glaciologist, but then the study of earthquakes became his most significant work. Reid was the first to establish that it is the fault that causes an earthquake, rather than a fault results from an earthquake. His elastic rebound theory, said that an earthquake occurs upon the sudden release of a large amount of stored energy after a long gradual accumulation of stress along a fault line. Later, modern science explained that Earth's surface consists of huge tectonic plates slowly moving relative to each other, and stress (elastic strain energy) gradually builds along their edges moving against each other. *TIS

1872 Bertrand Russell. 3rd Earl Russell, OM, FRS (18 May 1872 – 2 February 1970), was a British philosopher, logician, mathematician, historian, and social critic. At various points in his life, he imagined himself in turn a liberal, a socialist, and a pacifist, but he also admitted that he had never been any of these things, in any profound sense. He was born in Wales, into one of the most prominent aristocratic families in Britain.
Russell led the British "revolt against idealism" in the early 1900s. He is considered one of the founders of analytic philosophy along with his predecessor Gottlob Frege and his protégé Ludwig Wittgenstein, and is widely held to be one of the 20th century's premier logicians. He co-authored, with A. N. Whitehead, Principia Mathematica, an attempt to ground mathematics on logic. His philosophical essay "On Denoting" has been considered a "paradigm of philosophy." His work has had a considerable influence on logic, mathematics, set theory, linguistics, and philosophy, especially philosophy of language, epistemology, and metaphysics. *Wik  (on page 378 they are able to outline a proof for 1+1=2, but first they need to define the operation of addition.... then along comes  Kurt Godel)
I include here a quote from his autobiography that is often shortened so that, what I believe was the critical last part of it, is not told:
At the age of eleven, I began Euclid, with my brother as my tutor. This was one of the great events of my life, as dazzling as first love. I had not imagined that there was anything so delicious in the world. After I had learned the fifth proposition, my brother told me that it was generally considered difficult, but I had found no difficulty whatever. This was the first time it had dawned upon me that I might have some intelligence. From that moment until Whitehead and I finished Principia Mathematica, when I was thirty-eight, mathematics was my chief interest, and my chief source of happiness. Like all happiness, however, it was not unalloyed. I had been told that Euclid proved things, and was much disappointed that he started with axioms. At first I refused to accept them unless my brother could offer me some reason for doing so, but he said: 'If you don't accept them we cannot go on', and as I wished to go on, I reluctantly admitted them pro tem. The doubt as to the premisses of mathematics which I felt at that moment remained with me, and determined the course of my subsequent work.

1889 Thomas Midgley Jr. (May 18, 1889 – November 2, 1944) was an American mechanical and chemical engineer. He played a major role in developing leaded gasoline (tetraethyl lead) and some of the first chlorofluorocarbons (CFCs), better known in the United States by the brand name Freon; both products were later banned from common use due to their harmful impact on human health and the environment. He was granted more than 100 patents over the course of his career.[2]

Midgley contracted polio in 1940 and was left disabled; in 1944, he was found strangled to death by a device he devised to allow him to get out of bed unassisted. It was reported to the public that he had been accidentally killed by his own invention, but his death was privately declared a suicide.

His legacy is one of inventing the two chemicals that did the greatest environmental damage. Environmental historian J. R. McNeill stated that he "had more adverse impact on the atmosphere than any other single organism in Earth's history." Author Bill Bryson remarked that he possessed "an instinct for the regrettable that was almost uncanny." Science writer Fred Pearce described him as a "one-man environmental disaster". *Wik

1901 Julius Adams Stratton (May 18, 1901 – June 22, 1994) was a U.S. electrical engineer and university administrator. He attended the University of Washington for one year, then transferred to the Massachusetts Institute of Technology (MIT), from which he graduated with a bachelor's degree in 1923 and a master's degree in electrical engineering (EE) in 1926. He then followed graduate studies in Europe and the Technische Hochschule of Zurich (ETH Zurich), Switzerland, awarded him the degree of Doctor of Science in 1927. *Wik He worked with the blind-landing research program during WWII to help develop Glide-slope-approach radar.  He served as the president of MIT between 1959 and 1966, after serving the university in several lesser posts, notably appointments to provost in 1949, vice president in 1951, and chancellor in 1956.

1939 Peter Andreas Grünberg (German pronunciation: [18 May 1939 – 7 April 2018) was a German physicist, and Nobel Prize in Physics laureate for his discovery with Albert Fert of giant magnetoresistance which brought about a breakthrough in gigabyte hard disk drives.
In 1986 he discovered the antiparallel exchange coupling between ferromagnetic layers separated by a thin non-ferromagnetic layer, and in 1988 he discovered the giant magnetoresistive effect (GMR). GMR was simultaneously and independently discovered by Albert Fert from the Université de Paris Sud. It has been used extensively in read heads of modern hard drives. Another application of the GMR effect is non-volatile, magnetic random access memory.

Apart from the Nobel Prize, work also has been rewarded with shared prizes in the APS International Prize for New Materials, the International Union of Pure and Applied Physics Magnetism Award, the Hewlett-Packard Europhysics Prize, the Wolf Prize in Physics and the 2007 Japan Prize. He won the German Future Prize for Technology and Innovation in 1998 and was named European Inventor of the Year in the category "Universities and research institutions" by the European Patent Office and European Commission in 2006.

1941 Malcolm Sim Longair (18 May 1941 - )Scottish astronomer, noted for his scholarship and teaching, who in 1980 was appointed by Royal Warrant Astronomer Royal for Scotland, a post he held until 31 Dec 1990. The title of Astronomer Royal for Scotland was created in 1834. As Jacksonian Professor of Natural Philosophy and head of Cavendish Laboratory at the University of Cambridge, UK, his research interests include the emission from dust in the distant universe, observational cosmology, galaxy formation, and gravitational lensing. He is the current Public Understanding of Physics Fellow of the Institute of Physics. *TIS

1944 James Greig Arthur CC FRSC FRS (born May 18, 1944) is a Canadian mathematician working on automorphic forms, and former President of the American Mathematical Society. He is a Mossman Chair and University Professor at the University of Toronto Department of Mathematics.Arthur taught at Yale from 1970 until 1976. He joined the faculty of Duke University in 1976. He has been a professor at the University of Toronto since 1978.  He was four times a visiting scholar at the Institute for Advanced Study between 1976 and 2002.
Arthur is known for the Arthur–Selberg trace formula, generalizing the Selberg trace formula from the rank-one case (due to Selberg himself) to general reductive groups, one of the most important tools for research on the Langlands program. He also introduced the Arthur conjectures.
Arthur was elected a Fellow of the Royal Society of Canada in 1981 and a Fellow of the Royal Society in 1992. In 1998 he was an Invited Speaker of the International Congress of Mathematicians in Berlin. He was elected a Foreign Honorary Member of the American Academy of Arts and Sciences in 2003. In 2012 he became a fellow of the American Mathematical Society. He was elected as a fellow of the Canadian Mathematical Society in 2019. *Wik

1946 Dame Celia Mary Hoyles, DBE, FAcSS, FIMA (née French; born 18 May 1946) is a British mathematician, educationalist and Professor of Mathematics Education at University College London (UCL), in the Institute of Education (IoE).
Hoyles began her career as a secondary school teacher, later becoming an academic. In the late 1980s she was co-presenter of Fun and Games, a prime time television quiz show about mathematics. With Arthur Bakker, Phillip Kent, and Richard B. Noss she is the co-author of Improving Mathematics at Work: The Need for Techno-Mathematical Literacies.

Hoyles served as president of the Institute of Mathematics and its Applications (IMA) from 2014 to 2015.[1 She served as chief adviser for mathematics to the government of the United Kingdom from 2004 to 2007 and as director of the National Centre for Excellence in the Teaching of Mathematics (NCETM) from 2007 to 2013.

In the 2004 New Year Honours, Hoyles was appointed Officer of the Order of the British Empire (OBE) 'for services to education'. In the 2014 New Year Honours, she was appointed Dame Commander of the Order of the British Empire (DBE) in recognition of her service as director of the National Centre for Excellence in the Teaching of Mathematics. She was elected a Fellow of the Academy of Social Sciences (FAcSS).

In 2003, she was awarded the first Hans Freudenthal Medal by the International Commission on Mathematical Instruction (ICMI) in recognition of 'the outstanding contribution that [she] has made to research in the domain of technology and mathematics education'. In 2010, she was awarded the first Kavli Education Medal by the Royal Society 'in recognition of her outstanding contribution to research in mathematics education'. *SAU

DEATHS

1924 Corrado Segre (20 August 1863 – 18 May 1924) was an Italian mathematician who is remembered today as a major contributor to the early development of algebraic geometry.
Segre developed his entire career at the University of Turin, first as a student of Enrico D'Ovidio. In 1883 he published a dissertation on quadrics in projective space and was named an assistant to professors in algebra and analytic geometry. In 1885 he also assisted in descriptive geometry. He began to instruct in projective geometry, as a stand-in for Giuseppe Bruno, from 1885 to 1888. Then for 36 years, he had the chair in higher geometry following D'Ovidio. Segre and Giuseppe Peano made Turin known in geometry, and their complementary instruction has been noted as follows:

"in the mid 1880s, these two very young researchers, Segre and Peano, both of them only just past twenty and both working at the University of Turin, were developing very advanced points of view on fundamental geometrical issues. Although their positions were quite different from one another, they were in some way more complementary than opposed. So it must come as no surprise that Turin was the cradle of some of the most interesting studies on such issues."

The Erlangen program of Felix Klein appealed early on to Segre, and he became a promulgator. First, in 1885 he published an article on conics in the plane where he demonstrated how group theory facilitated the study.

1954 Selig Brodetsky ( 10 February 1888 – 18 May 1954) was a Russian-born English mathematician, a member of the World Zionist Executive, the president of the Board of Deputies of British Jews, and the second president of the Hebrew University of Jerusalem.
In 1908, he completed his studies with highest honours being Senior Wrangler, to the distress of the conservative press, which was forced to recognise that a son of immigrants surpassed all the local students. The Newton scholarship enabled him to study at Leipzig University where he was awarded a doctorate in 1913. His dissertation dealt with the gravitational field.
He became a lecturer at Bristol and later lecturer and professor at Leeds. He worked on fluid flow with particular emphasis on aerodynamics.

1965 Eduard Jan Dijksterhuis (28 October 1892 in Tilburg – 18 May 1965 in De Bilt) was a Dutch historian of science.

Dijksterhuis studied mathematics at the University of Groningen from 1911 to 1918. His Ph.d. thesis was entitled "A Contribution to the Knowledge of the Flat Helicoid."

From 1916 to 1953 he was a professor and taught mathematics, physics and cosmography. He advocated changes in the way mathematics was taught to reinforce its formal characteristics. In 1950, he was appointed as a German member of the Royal Netherlands Academy of Arts and Sciences.  In 1953, he was appointed to teach mathematics history and the nature of science at Utrecht University and in 1955 at Leiden University.

His first biography was on the life and work of Archimedes, published in Dutch in 1938. It was translated into English by C. Dikshoorn in 1956, published in Copenhagen by Munksgard. Princeton University Press republished it, with additional commentary, in 1987.

In 1943 he wrote on the life and times of Simon Stevin, again first in Dutch, which Dikshoorn translated for English publication in 1970.

Upon the completion of Huygens Collected Works in 1950, at the annual meeting of the Dutch Society of Sciences at Haarlem, Dijksterhuis spoke on the 60-year project. The text of his speech was published in Centaurus in March 1953, when he gave a "sketch of the position occupied by Huygens in the scientific life of the 17th century."

1996 Stefan Schwarz (18 May 1914 in Nové Mesto nad Váhom, Austria-Hungarian Empire (now Slovakia) - 6 Dec 1996 in Bratislava, Slovak Republic) In addition to his work on semigroups, number theory and finite fields, Schwarz contributed to the theory of non-negative and Boolean matrices.
Schwarz organised the first International Conference on Semigroups in 1968. At this conference setting up the journal Semigroup Forum was discussed and Schwarz became an editor from Volume 1 which appeared in 1970, continuing as editor until 1982. This was not his first editorial role since he had been an editor of the Czechoslovak Mathematical Journal from 1945 and continued to edit this journal until he was nearly 80 years old. He also founded the Mathematico-Physical Journal of the Slovak Academy of Sciences in 1950 and continued as an editor of the mathematics part of the journal when it split from the physics part to become Mathematica Slovaca until 1990. *SAU

2007 Pierre-Gilles de Gennes French physicist who was awarded the 1991 Nobel Prize for Physics for "discovering that methods developed for studying order phenomena in simple systems can be generalized to more complex forms of matter, in particular to liquid crystals and polymers." He described mathematically how, for example, magnetic dipoles, long molecules or molecule chains can under certain conditions form ordered states, and what happens when they pass from an ordered to a disordered state. Such changes of order occur when, for example, a heated magnet changes from a state in which all the small atomic magnets are lined up in parallel to a disordered state in which the magnets are randomly oriented. Recently, he has been concerned with the physical chemistry of adhesion. *TIS

Credits:
*CHM=Computer History Museum
*FFF=Kane, Famous First Facts
*NSEC= NASA Solar Eclipse Calendar
*RMAT= The Renaissance Mathematicus, Thony Christie
*SAU=St Andrews Univ. Math History
*TIA = Today in Astronomy
*TIS= Today in Science History
*VFR = V Frederick Rickey, USMA
*Wik = Wikipedia
*WM = Women of Mathematics, Grinstein & Campbell