## Wednesday, 13 May 2015

### On This Day in Math - May 13

In mathematics you don't understand things.
You just get used to them.

~ Johann von Neumann

The 133rd day of the year; 133 is a "happy number".  If you sum the squares of the digits and then repeat the process and the sum will eventually come to one. (12 + 32+32= 19 ... ===  82 === 68 === 100 ====1) Some numbers, "unhappy ones", never reach one. (Student's might explore happy numbers to find how many times the process must be iterated for different numbers to reach one, for example I(133) = 5  Alternatively, curious students may wonder what happens to the "unhappy" numbers if they never reach one.)
133 is a repdigit in base 11 (111) and base 18 (77),

EVENTS
1637 the table knife was created by Cardinal Richelieu in France. Until this time, daggers were used to cut meat, as well as to pick one's teeth. Richelieu had the points rounded off all of the knives to be used at his table *TIS

1673 Scottish mathematician, physicist and optician James Gregory in a letter to John Collins, he remarks on diffraction:
If ye think fit, ye may signify to Mr. Newton a small experiment, which (if he know it not already) may be worthy of his consideration. Let in the sun’s light by a small hole to a darkened house, and at the hole place a feather, (the more delicate and white the better for this purpose,) and it shall direct to a white wall or paper opposite to it a number of small circles and ovals, (if I mistake them not) whereof one is somewhat white, (to wit, the middle, which is opposite to the sun,) and all the rest severely coloured. I would gladly hear his thoughts of it.
*Thony Christie, The Renaissance Mathematicus

1733 Swedish Astronomer Birger Wassenius reports on the Eclipse and attributes solar prominences to the Moon:
I can tell you is this, that I soon after the sun's total extinction became aware of some small lighter spots UTI the bright ring, or the atmosphere, about 3 or 4, of different temperament and size, which set in towards the moon's periphery , but at no point next to it. As is now not the moon altogether at one time could fall into my eyes through a long tube, so I had particularly esteem of the largest of these spots, which in the tube appeared on the northeast side of the moon. Being that as composed of three reddish cloud drops placed adjacent to one side, with darker colors or stripes in between, such as the figure below shows fairly. "
*Astronomer Guide

In 1769 Britain's Board of Longitude awarded 10 Pounds to Israel Lyons, Mathematician for, "Reward for his solution to a problem proposed by the late Dr Halley which the Commissioners of Longitude think will be useful to Navigation."  The problem seemed to be related to "traverse sailing."  In June of 1775 his widow would receive an additional 31.50 Pounds for "some of her husband's Problems & Solutions which have been given up by her..." *Derek Howse, Britain's Board of Longitude: The Finances, 1714-1828

1829 Charles-Francois Sturm presented his theorem for ﬁnding the number of real roots of a polynomial equation to the French Academy. *VFR

In 1890, Nikola Tesla was issued a patent for an electric generator (No. 428,057). *TIS

1940 aviation pioneer Igor Sikorsky made the maidenflight with his newly developed helicopter VS-300 *@yovisto

2010  The Times reported on 13 May 2010 that Foucault's original Pendulum is damaged, "Historic instrument is irreparably damaged in an accident at a Paris museum. The original pendulum, which was used by French scientist Leon Foucault to demonstrate the rotation of the Earth and which forms an integral part of Eco's novel's labyrinthine plot, has been irreparably damaged in an accident in Paris. The pendulum's cable snapped last month and its sphere crashed to the marble floor of the Musee des Arts et Metiers. In 1851, Foucault used the pendulum to perform a sensational demonstration in the Paris Pantheon, proving to Napoleon III and the Parisian elite that the Earth revolved around its axis. Such was its success that the experiment was replicated throughout Europe.
Thierry Lalande, the museum's ancient scientific instruments curator, said that the pendulum's brass bob had been badly damaged in three places and could not be restored.
"It's not a loss, because the pendulum is still there, but it's a failure because we were unable to protect it," he said. The circumstances surrounding the accident have raised eyebrows in France.
The museum regularly hosts cocktail parties in the chapel that houses the pendulum, and Mr Lalande admitted that several alarming incidents had occurred over the past year. In May 2009, for example, a partygoer grabbed the 28kg instrument and swung it into a security barrier. *Times Higher Education

2011 Friday the 13th.  The thirteenth of the month is more likely to occur on Friday than on any other day of the week.
Each Gregorian 400-year cycle contains 146,097 days (365 × 400 = 146,000 normal days, plus 97 leap days) and they equal 146,097 days, total. 146,097 ÷ 7 = 20,871 weeks. Thus, each cycle contains the same pattern of days of the week (and thus the same pattern of Fridays that are on the 13th). The 13th day of the month is slightly more likely to be a Friday than any other day of the week.   On average, there is a Friday the 13th once every 212.35 days (compared to Thursday the 13th, which occurs only once every 213.59 days).
According to the Stress Management Center and Phobia Institute in Asheville, North Carolina, an estimated 17 to 21 million people in the United States are affected by a fear of this day. Some people are so paralyzed by fear that they avoid their normal routines in doing business, taking flights or even getting out of bed. "It's been estimated that [US]$800 or$900 million is lost in business on this day". Despite this, representatives for both Delta and Continental Airlines say that their airlines do not suffer from any noticeable drop in travel on those Fridays.
According to folklorists, there is no written evidence for a "Friday the 13th" superstition before the 19th century. The earliest known documented reference in English occurs in Henry Sutherland Edwards' 1869 biography of Gioachino Rossini.

2012 will have Friday the 13ths in January, April and July *Wik

2013 Peruvian mathematician Harald Andrés Helfgott releases pre-print claiming a completed proof of the weak Goldbach Conjecture. The weak, or ternary, Goldbach conjecture states that every odd integer greater than 5 can be written as the sum of three primes; *The Value of the Variable at Wordpress.com

BIRTHS
1750 Lorenzo Mascheroni
(May 13, 1750 – July 14, 1800) was a geometer who proved in 1797 that all Euclidean constructions can be made with compasses alone, so a straight edge in not needed.*SAU He is also known for the Euler–Mascheroni constant which gives the limit of the difference between ln(n) and the sum of the harmonic series for the first n terms. The constant first appeared in a 1735 paper by the Swiss mathematician Leonhard Euler, titled De Progressionibus harmonicis observationes (Eneström Index 43). Euler used the notations C and O for the constant. In 1790, Italian mathematician Lorenzo Mascheroni used the notations A and a for the constant. The notation γ appears nowhere in the writings of either Euler or Mascheroni, and was chosen at a later time because of the constant's connection to the gamma function. For example, the German mathematician Carl Anton Bretschneider used the notation γ in 1835. *Wikipedia, with editing He was also a founder of the science of mechanics, asserting that the velocity of a falling body was independent of its weight.

1753 Lazare-Nicolas-Marguerite Carnot (13 May 1753 – 2 August 1823)  who published his "Reﬂections on the Metaphysics of the Inﬁnitesimal Calculus" in 1797. It was written in 1784 for a competition of the Berlin academy seeking a “clear and precise” foundation for the calculus. *VFR  His son Sadi Carnot was a founder of the field of thermodynamics and the theory of heat engines .  He is better known outside of mathematics as a military tactician and politician.

1931 András Hajnal (May 13, 1931 - ) is an emeritus professor of mathematics at Rutgers University and a member of the Hungarian Academy of Sciences known for his work in set theory and combinatorics. Hajnal is the author of over 150 publications. Among the many co-authors of Paul Erdős, he has the second largest number of joint papers, 56. With Peter Hamburger, he wrote a textbook, Set Theory*Wik

DEATHS
1826 Christian Kramp,
(July 8, 1760 – May 13, 1826) As Bessel, Legendre and Gauss did, Kramp worked on the generalised factorial function which applied to non-integers. His work on factorials is independent of that of Stirling and Vandermonde. The word factorial is reported to be the creation of Louis François Antoine Arbogast (1759-1803). The symbol now commonly used for factorial seems to have been created by Christian Kramp in 1808. It is referred to as "Kramp's notation" in Chrystal's famous Algebra.

1878 Joseph Henry (17 Dec 1797, 13 May 1878 at age 80) One of the first great American scientists after Benjamin Franklin. Although Henry at an early age appeared to be headed for a career in the theater, a chance encounter with a book of lectures on scientific topics turned his interest to science. He aided Samuel F.B. Morse in the development of the telegraph and discovered several important principles of electricity, including self-induction, a phenomenon of primary importance in electronic circuitry. He was the first Secretary (director) of the Smithsonian Institution (1846-1878), where he established the foundation of a national weather service. For more than thirty years, Henry insisted that basic research was of fundamental importance. *TIS

1939 Stanisław Leśniewski (March 30, 1886, Serpukhov – May 13, 1939, Warsaw) was a Polish mathematician, philosopher and logician. Leśniewski belonged to the first generation of the Lwów-Warsaw School of logic founded by Kazimierz Twardowski. Together with Alfred Tarski and Jan Łukasiewicz, he formed the troika which made the University of Warsaw, during the Interbellum, perhaps the most important research center in the world for formal logic. *Wik

1944 William Edward Hodgson Berwick (11 March 1888 in Dudley Hill, Bradford – 13 May 1944 in Bangor, Gwynedd) was a British mathematician, specializing in algebra, who worked on the problem of computing an integral basis for the algebraic integers in a simple algebraic extension of the rationals.*Wik

1983 Otto (Hermann Leopold) Heckmann (23 Jun 1901, 13 May 1983 at age 81) was a German astronomer noted for measuring stellar positions and his studies of relativity and cosmology. He also made notable contributions to statistical mechanics. In 1931, He proved that, under the assumptions that matter is homogeneously distributed throughout the universe and is isotropic (having identical properties in every direction), the theory of general relativity could result in an open, or Euclidean, universe as readily as a closed one. Heckmann organized an international program to photograph and chart the positions of the stars in the Northern Hemisphere, which led to the publication in 1975 of the third German Astronomical Society catalog, Astronomische Gesellschaft Katalog (AGK3). *TIS

1984 Stanislaw Marcin Ulam (13 April 1909 – 13 May 1984)  Polish-American mathematician who played a major role in the development of the hydrogen bomb at Los Alamos. He solved the problem of how to initiate fusion in the hydrogen bomb by suggesting that compression was essential to explosion and that shock waves from a fission bomb could produce the compression needed. He further suggested that careful design could focus mechanical shock waves in such a way that they would promote rapid burning of the fusion fuel. Ulam, with J.C. Everett, also proposed the "Orion" plan for nuclear propulsion of space vehicles. While Ulam was at Los Alamos, he developed "Monte-Carlo method" which searched for solutions to mathematical problems using a statistical sampling method with random numbers. *TIS He is buried in Santa Fe National Cemetery in Santa Fe, New Mexico, USA

“While chatting at the Scottish Caf´e with Borsuk, an outstanding Warsaw topologist, he [Ulam] saw in a ﬂash the truth of what is now called the Borsuk-Ulam theorem. Borsuk had to commandeer all his technical resources to prove it.” For n = 2, this theorem can be interpreted as asserting that some point on the globe has precisely the same weather as its antipodal point. The ‘weather’ has to mean two variables (R2) that vary continuously (f) on the surface (S 2) of the earth. Perhaps temperature and humidity will do? *theoremoftheday.org

2005 George Bernard Dantzig (November 8, 1914 – May 13, 2005) was an American mathematical scientist who made important contributions to operations research, computer science, economics, and statistics.
Dantzig is known for his development of the simplex algorithm, an algorithm for solving linear programming problems, and his work with linear programming, some years after it was invented by the Soviet mathematician & economist Leonid Kantorovich. In statistics, Dantzig solved two open problems in statistical theory, which he had mistaken for homework after arriving late to a lecture of Jerzy Neyman.
Dantzig was the Professor Emeritus of Transportation Sciences and Professor of Operations Research and of Computer Science at Stanford. *Wik

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