## Saturday, 5 March 2016

### On This Day in Math - March 5

 Terrestrial globe by Mercator dating from 1541. It is now in the museum collection of the Palazzo Ducale in Urbania, Italy, and is one of about 22 existing Mercator globes.*Wik

But in the present century, thanks in good part to the influence of Hilbert, we have come to see that the unproved postulates with which we start are purely arbitrary. They must be consistent, they had better lead to something interesting.
~Julian Lowell Coolidge

The 65th day of the year; 65 is the smallest hypotenuse of two different primitive Pythagorean triangles (and of two other triangles that are not primitive) with all integral sides. (Don't just sit there, find them!)

And $65 = 1^5 + 2^4 + 3^3 + 4^2 + 5^1$ *jim wilder ‏@wilderlab

65 is the constant of a 5x5 normal magic square.

Euler found 65 integers, which he called "numeri idonei," that could be used to prove the primality of certain numbers.[idoneal numbers (also called suitable numbers or convenient numbers) are the positive integers D such that any integer expressible in only one way as $x^2 ± Dy^2$ (where x2 is relatively prime to Dy2) is a prime, prime power, twice one of these, or a power of 2. In particular, a number that has two distinct representations as a sum of two squares (such as 65) is composite. Every idoneal number generates a set containing infinitely many primes and missing infinitely many other primes.]

65 is also the smallest Fermat semiprime [A Fermat number, $2^{2^n} +1$ that is factorable into two primes. Fermat conjectured they were all prime]

EVENTS
In 1223 BC, the oldest recorded eclipse occurred, according to one plausible interpretation of a date inscribed on a clay tablet retrieved from the ancient city of Ugarit, Syria (as it is now). This date is favoured by recent authors on the subject, although alternatively 3 May 1375 BC has also been proposed as plausible. Certainly by the 8th century BC, the Babylonians were keeping a systematic record of solar eclipses, and possibly by this time they may have been able to apply numerological rules to make fairly accurate predictions of the occurrence of solar eclipses. The first total solar eclipse reliably recorded by the Chinese occurred on 4 Jun 180 BC*TIS

In 1590, Tycho Brahe discovered a comet in the constellation Pisces.*TIS

In 1616, Copernican theory was declared "false and erroneous" in a decree delivered by Cardinal Robert Bellarmine, and issued by the Catholic Church in Rome. Further, no person was to be permitted to hold or teach the theory that the earth revolves around the sun. When Galileo subsequently violated the decree, he was put on trial and held under house arrest for the final eight years of his life. *TIS Copernican theory was declared "false and erroneous" by the 11 theologians, appointed by the Pope to examine it, on 24 February 1616. Bellarmine, who was not one of these 11, was ordered by the Pope to convey this decision to Galileo, which he did verbally on 26 February 1616. The Decree of the Index was issued on 5 March 1616 in which "…the books by Nicolaus Copernicus and Diego Zúñiga be suspended until corrected…" This decree was signed by the Most Illustrious and Reverend Lord Cardinal of St. Cecilia, Bishop of Albano P. (Paolo Sfondrati) and Fra Francisco Magdelenus Capiferreus, O.P., Secretary. *Thony Christie, My thanks to Thony for the correction More detail about this event can be found on the Feb 26 Post about Galileo

1639 Debeaune to Mersenne: “I do not think that one could acquire any solid knowledge of nature in physics without geometry, and the best of geometry consists of analysis, of such kind that without the latter it is quite imperfect.” *VFR

1673 Hooke presents Arithmetic Engine to Royal Society. After a presentation of a calculating machine by Leibniz on January 22, (after which Leibniz complained to Oldgenburg that Hooke's examination of the machine had shown "almost indecent interest") Hooke became interested in creating a better machine and announced such intention to the Royal Society. Working with Richard Shortgrave, Harry Hunt and John Pell he produced a machine which would multiply to twenty places over the next six weeks. His diary entry seemed to indicate the demonstration went well, but within a few days he seemed to have dismissed such machines entirely. *Stephen Inwood, Forgotten Genius

1684 Halley's father mysteriously went missing and five weeks later was found murdered on the banks of the Medway. *Kate Morant, halleyslog.wordpress.com

On March 5, 1750, Euler read his own Recherches sur la Précession at the Berlin Academy. Two days later he wrote d'Alembert giving an extended account of his struggle to derive the precession and giving d'Alembert credit for re-inspiring his efforts to solve it. * Curtis Wilson, Historia Mathematica, Volume 35, Issue 4, November 2008, Pages 329–332

1831 Birth of "The Average Man". Adolphe Quetelet read a memoir to the Brussels Academy Royal. The newborn l'homme moyen would not be officially named by quetelet until July. *Statistics on the Table: The History of Statistical Concepts and Methods
By Stephen M. Stigler

1876 Sylvester, at age 61, appointed professor of mathematics at Johns Hopkins University. This was the real beginning of graduate mathematics education in the United States. *VFR

1960 Gao–Guenie (H5 ordinary chondrite) meteorites fell in Burkina Faso on March 5, 1960 at 17:00 (local time). After three separate detonations, several thousands of stones rained down over an area of about 70 square kilometres (27 sq mi). The sound of the fall was heard as far as Ouagadougou, which is 100 kilometers (62 mi) away. Eyewitnesses said that some trees were broken and henhouses destroyed. The largest stones recovered weigh up to 10 kilograms (22 lb)*Wik

1963 On this day in 1963, the Hula-Hoop, a hip-swiveling toy that became a huge fad across America when it was first marketed by Wham-O in 1958, is patented by the company’s co-founder, Arthur “Spud” Melin. An estimated 25 million Hula-Hoops were sold in its first four months of production alone. *http://www.history.com

1993 Talking Laptop Helps Blind Student Earn B.S.:
In an early demonstration of the impact computers could have on people's lives, the Los Angeles Times reports that a blind student was taking advantage of a talking laptop computer to help him complete courses necessary to graduate from UCLA. After 15 years of going to college on and off, the computer provided Robert Antunez the independence and aid he needed to complete a bachelor's degree in political science. *CHM

BIRTHS
1512 Gerardus Mercator (5 Mar 1512- 2 Dec 1594) Flemish cartographer whose most important innovation was a map, embodying what was later known as the Mercator projection, on which parallels and meridians are rendered as straight lines spaced so as to produce at any point an accurate ratio of latitude to longitude. He also introduced the term atlas for a collection of maps. *TIS A nice blog about the Mercator projection, which he suggests should be called the Mercator Wright projection is at the Renaissance Mathematicus blogsite.
For those interested in a quick look at the math involved in the Merator-Wright projection, this Endeavour blog by John D. Cook may help.

1575 William Oughtred (5 Mar 1575; 30 Jun 1660 at age 85) English mathematician and Episcopal minister who invented the earliest form of the slide rule, two identical linear or circular logarithmic scales held together and adjusted by hand. Improvements involving the familiar inner rule with tongue-in-groove linear construction came later. He also introduced the familiar multiplication sign x in a 1631 textbook, along with the first use of the abbreviations sin, cos and tan.*Tis There is an Oughtred Society dedicated to the history and preservation of slide rules.

1624/25 John Collins (5 March 1624 in Wood Eaton (4km north of Oxford), England - 10 Nov 1683 in London, England) was an accountant and publisher who corresponded extensively with the mathematicians of his day. Collins's importance is, as Barrow said, being "the English Mersenne" . He corresponded with Barrow, David Gregory, James Gregory, Newton, Wallis, Borelli, Huygens, Leibniz, Tschirnhaus and Sluze.
Collins published books by Barrow and Wallis and left a collection of 2000 books and an uncounted number of manuscripts.
He did publish works of his own, however. For instance he published works on sundials, trigonometry for navigation and the use of the quadrant. He had a paper on cartography published and also wrote on accounting, compound interest and annuities. His major works were An introduction to merchant's accounts (1652), The sector on a quadrant (1658), Geometrical dialling (1659), The mariner's plain scale new plained (1659) and, in 1664, he published Doctrine of Decimal Arithmetick. *SAU

1779 Benjamin Gompertz (March 5, 1779 – July 14, 1865), was a self educated mathematician, denied admission to university because he was Jewish.[citation needed] Nevertheless he was made Fellow of the Royal Society in 1819. Gompertz is today mostly known for his Gompertz law (of mortality), a demographic model published in 1825. The model can be written in this way:

N(t) = N(0) e-c (e{at}-1),

where N(t) represents the number of individuals at time t, and c and a are constants.

This model is a refinement of the demographic model of Malthus. It was used by insurance companies to calculate the cost of life insurance. The equation, known as a Gompertz curve, is now used in many areas to model a time series where growth is slowest at the start and end of a period. The model has been extended to the Gompertz–Makeham law of mortality.

1794 Jacques Babinet (5 March 1794 – 21 October 1872) was a French physicist, mathematician, and astronomer who is best known for his contributions to optics. A graduate of the École Polytechnique, which he left in 1812 for the Military School at Metz, he was later a professor at the Sorbonne and at the Collège de France. In 1840, he was elected as a member of the Académie Royale des Sciences. He was also an astronomer of the Bureau des Longitudes.
Among Babinet's accomplishments are the 1827 standardization of the Ångström unit for measuring light using the red Cadmium line's wavelength, and the principle (Babinet's principle) that similar diffraction patterns are produced by two complementary screens. He was the first to suggest using wavelengths of light to standardize measurements. His idea was first used between 1960 and 1983, when a meter was defined as a wavelength of light from krypton gas.
In addition to his brilliant lectures on meteorology and optics research, Babinet was also a great promoter of science, an amusing and clever lecturer, and a brilliant, entertaining and prolific author of popular scientific articles. Unlike the majority of his contemporaries, Babinet was beloved by many for his kindly and charitable nature. He is known for the invention of polariscope and an optical goniometer. *Wik

1815 Angelo Genocchi (5 March 1817 – 7 March 1889) was an Italian mathematician who specialized in number theory. He worked with Giuseppe Peano. The Genocchi numbers are named after him. G(t)= 2t/(et+1)for integer values of t. The first few are 1, −1, 0, 1, 0, −3, 0, 17...(A001469 in OEIS)
Genocchi was President of the Academy of Sciences of Turin.*Wik

1880 Sergei Natanovich Bernstein (March 5, 1880 – October 26, 1968) was a Russian and Soviet mathematician. His doctoral dissertation, submitted in 1904 to the Sorbonne, solved Hilbert's nineteenth problem on the analytic solution of elliptic differential equations. Later, he published numerous works on Probability theory, Constructive function theory, and mathematical foundations of genetics. From 1906 until 1933, Bernstein was a member of the Kharkov Mathematical Society. *Wik

1885 Pauline Sperry born in Peabody, Massachusetts. After graduating Phi Beta Kappa from Smith College in 1906 she taught several years before doing graduate work at the University of Chicago under the projective differential geometer Ernest Julius Wilczynski (1876–1932). Her doctoral thesis, "Properties of a certain projectively defined two-parameter family of curves on a general surface", drew on his work as the founder of the American school of projective differential geometry. After receiving her Ph.D. in 1916 she taught at the University of California at Berkeley, becomming the ﬁrst woman to be promoted to assistant professor in mathematics (in 1923). In 1950 she was ﬁred for refusing to sign a loyalty oath.

1915 Laurent-Moïse Schwartz (5 March 1915 in Paris – 4 July 2002 in Paris) was a French mathematician. He pioneered the theory of distributions, which gives a well-defined meaning to objects such as the Dirac delta function. He was awarded the Fields medal in 1950 for his work (developing the theory of distributions, a new notion of generalized functions motivated by the Dirac delta-function of theoretical physics). He was the first French mathematician to receive the Fields medal. For a long time he taught at the École polytechnique. *Wik

1931 Vera S. Pless (born 1931) is an American mathematician specializing in combinatorics and coding theory. She is professor emeritus at the University of Illinois at Chicago. She has co-authored several articles with John H. Conway, giving her an Erdős number of 2.*Wik

DEATHS
1827 Pierre Simon, Marquis de Laplace (23 Mar 1749, 5 Mar 1827 at age 78) was a French mathematician, physicist, statistician and astronomer known for his mathematical analysis of the stability of the solar system (1773), alleviating Isaac Newton's concerns about perturbations between planets. He took an exact approach to science. He developed an explanation of surface tension of a liquid in terms of inter-molecular attractions, investigated capillary action and the speed of sound. He assisted Antoine Lavoisier (1783) investigating specific heat and heats of combustion, initiating the science of thermochemistry. He believed the solar system formed from a collapsing nebula. He contributed to the mathematics of probability and calculus, in which a differential equation is known by his name, and was involved in establishing the metric system.*TIS His last words were, “What we know is very slight; what we don’t know is immense.” *Eves, Revisited, 319◦

1827 Count Alessandro Giuseppe Antonio Anastasio Volta (18 Feb 1745; 5 Mar 1827 at age 82) Italian physicist who invented the electric battery (1800), which for the first time enabled the reliable, sustained supply of current. His voltaic pile used plates of two dissimilar metals and an electrolyte, a number of alternated zinc and silver disks, each separated with porous brine-soaked cardboard. Previously, only discharge of static electricity had been available, so his device opened a new door to new uses of electricity. Shortly thereafter, William Nicholson decomposed water by electrolysis. That same process later enabled Humphry Davy to isolate potassium and other metals. Volta also invented the electrophorus, the condenser and the electroscope. He made important contributions to meteorology. His study of gases included the discovery of methane. The volt, a unit of electrical measurement, is named after him.*TIS

1875 Claude-Louis Mathieu (25 Nov 1783; 5 Mar 1875) French astronomer and mathematician who worked particularly on the determination of the distances of the stars. He began his career as an engineer, but soon became a mathematician at the Bureau des Longitudes in 1817 and later professor of astronomy in Paris. For many years Claude Mathieu edited the work on population statistics L'Annuaire du Bureau des Longitudes produced by the Bureau des Longitudes. His work in astronomy focussed on determining the distances to stars. He published L'Histoire de l'astronomie au XVIII siècle in 1827. *TIS

1905 Karol Borsuk (May 8, 1905, Warsaw – January 24, 1982, Warsaw) Polish mathematician. His main interest was topology.
Borsuk introduced the theory of absolute retracts (ARs) and absolute neighborhood retracts (ANRs), and the cohomotopy groups, later called Borsuk-Spanier cohomotopy groups. He also founded the so called Shape theory. He has constructed various beautiful examples of topological spaces, e.g. an acyclic, 3-dimensional continuum which admits a fixed point free homeomorphism onto itself; also 2-dimensional, contractible polyhedra which have no free edge. His topological and geometric conjectures and themes stimulated research for more than half a century. *Wikipedia

1925 Johan Ludwig William Valdemar Jensen (8 May 1859 in Nakskov, Denmark - 5 March 1925 in Copenhagen, Denmark)contributed to the Riemann Hypothesis, proving a theorem which he sent to Mittag-Leffler who published it in 1899. The theorem is important, but does not lead to a solution of the Riemann Hypothesis as Jensen had hoped. It expresses, "... the mean value of the logarithm of the absolute value of a holomorphic function on a circle by means of the distances of the zeros from the center and the value at the center. "
He also studied infinite series, the gamma function and inequalities for convex functions.*SAU

1840 Franz Carl Joseph Mertens (20 March 1840 in Schroda, Posen, Prussia (now Środa Wielkopolska, Poland) - 5 March 1927 in Vienna, Austria) Mertens worked on a number of different topics including potential theory, geometrical applications to determinants, algebra and analytic number theory, publishing 126 papers. Bruce C Berndt writes, "Mertens is perhaps best known for his determination of the sign of Gauss sums, his work on the irreducibility of the cyclotomic equation, and the hypothesis which bears his name. "
Many people are aware of Mertens contributions since his elementary proof of the Dirichlet theorem appears in most modern textbooks. However he made many deep contributions including Mertens' theorems, three results in number theory related to the density of the primes. He proved these results using Chebyshev's theorem, a weak version of the prime number theorem. *SAU
In his youth, Mertens moved to Berlin where he became a student at Berlin
University, and where he studied under Kronecker and Kummer. Mertens first worked in Krakow, and then moved to Austria. Ernst Fischer and Schrodinger, for instance, were students of Mertens at the University of Vienna. *Julio Gonzalez Cabillon, Historia Matematica Discussions

1885 John Radford Young (1799– March 5,1885; Peckam, England) was a mathematician, professor and author, who was almost entirely self-educated. At an early age he became acquainted with Olinthus Gilbert Gregory, who perceived his mathematical ability and assisted him in his studies.
In 1833, he was appointed Professor of Mathematics at Belfast College. When Queen's College, Belfast, opened in 1849, the Presbyterian party in control there prevented Young's reappointment as Professor in the new establishment. From that time he devoted himself more completely to the study of mathematical analysis, and made several original discoveries. He appears to have been the first to use the term "circular function" when he used it in 1831 in the an edition of Elements of the Differential Calculus "Thus, ax, a log x, sin x, &c., are transcendental functions: the first is an exponential function, the second a logarithmic function, and the third a circular function"
In 1847, he published in the Transactions of the Cambridge Philosophical Society a paper "On the Principle of Continuity in reference to certain Results of Analysis", and, in 1848, in the Transactions of the Royal Irish Academy a paper "On an Extension of a Theorem of Euler". As early as 1844, he had discovered and published a proof of Newton's rule for determining the number of imaginary roots in an equation. In 1866, he completed his proof, publishing in The Philosophical Magazine a demonstration of a principle which in his earlier paper he had assumed as axiomatic. In 1868, he contributed to the Proceedings of the Royal Irish Academy a memoir "On the Imaginary Roots of Numerical Equations".
*Wik

1930 Christine Ladd-Franklin (1 Dec 1847; 5 Mar 1930) American scientist and logician known for contributions to the theory of colour vision accounting for the development of man's color sense which countered the established views of Helmholtz, Young, and Hering. Her position was that color-sense developed in stages. Ladd- Franklin's conclusions were particularly useful in accounting for color-blindness in some individuals. In logic, she published an original method for reducing all syllogisms to a single formula *TIS Ladd-Franklin was the first woman to have a published paper in the Analyst. She was also the first woman to receive a Ph.D. in mathematics and logic. The majority of her publications were based on visual processes and logic. Her views on logic influenced Charles S. Peirce’s logic and she was highly praised by Prior. *Wik

1954 Julian Lowell Coolidge (28 Sep 1873, 5 Mar 1954 at age 80) American mathematician and educator who published numerous works on theoretical mathematics along the lines of the Study-Segre school. Coolidge received a B.A. at Harvard (1895), then in England he graduated (1897) with a B.Sc. from Balliol College Oxford. (It is interesting that this degree from Oxford was in natural science and it was the first natural science degree ever awarded by Oxford.) He taught at Groton School, Conn. (1897-9) where one of his pupils was Franklin D Roosevelt, the future U.S. president. From 1899 he taught at Harvard University. Between 1902 and 1904, he went to Turin to study under Corrado Segre and then to Bonn where he studied under Eduard Study. His Mathematics of the Great Amateurs is perhaps his best-known work. *TIS . This geometer wrote several noteworthy books on the history of geometry.*VFR

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