"If equations are trains threading the landscape of numbers,

then no train stops at pi. "

~Richard Preston

The 103rd day of the year; there are 103 geometrical forms of magic knight's tour of the chessboard.

103 is the reverse of 301. The same is true of their squares: 103

^{2}= 10609 and 301

^{2}= 90601. *Jim Wilder

The smallest prime whose reciprocal contains a period that is exactly 1/3 of the maximum length. (The period of the reciprocal of a prime p is always a divisor of p-1, so for 103 the period is 102/3 = 34. )

Using a standard dartboard, 103 is the smallest possible prime that cannot be scored with two darts.

EVENTS

In 1633 Galileo Galilei’s investigation by the Roman Inquisition began. At its conclusion, his belief that the Earth was not the center of the Universe was pronounced heretical.*Thony Christie, *TIS **1749**Euler succeeded in proving Fermat's theorem on sums of two squares in 1749, when he was forty-two years old. He communicated this in a letter to Goldbach #OTD.

Fermat's theorem on sums of two squares asserts that an odd prime number p can be expressed as

p = x^2 + y^2

with integer x and y if and only if p is congruent to 1 (mod 4). The statement was announced by Fermat in 1640, but he supplied no proof. *Wik

1803 A letter from Dalton to "Respected Friend" describes his theory that "If a quantity of water thus freed from air be agitated in any kind of gas, not chemically uniting with water, it will absorb its bulk of the gas, or otherwise a part of it equal to some one of the following fractions, namely, 1/8, 1/27, 1/64, 1/125, &c. these being the cubes of the reciprocals of the natural numbers " He then goes on to add that " I am just upon the point of discovering something superior to any of those already published, & which may be of as much importance to science as that of Gravitation itself. I mean the nature of Heat & all its combinations with substances." This may be the earliest note by Dalton of his atomic theory as it precedes his first lab notebook entry of 6 September by five months. This would be the basis for a paper read to the Literary and Philosophical Society of Manchester on Oct. 21, 1803.

1804 Gauss is made a fellow of the Royal Society of London

1888, a French newspaper mistakenly published an obituary for Alfred Nobel, inventor of dynamite, calling him “"a merchant of death.” The mistake was that it was actually Alfred's brother, Ludwig Nobel, who had just died (at age 56, due to heart trouble). However, shocked by the newspaper's report, Nobel began to seek a change in public opinion, which led to his decision to establish the Nobel Prizes.*TIS

1898 In 1898, Marie Curie observed a meeting of the French Academy of Sciences, where one of her teachers, Prof. Gabriel Lippmann announced her discovery of substances much more radioactive than uranium. Working since Dec 1897, she had verified that the radiant activity of various compounds was directly related to the amount of uranium present, whether solid, powdered, or in a wet state. She proposed the radiant activity was an atomic property, for it was independent of physical or chemical state. She announced that in pitchblende and charcolite she had discovered compounds even more active than uranium. (She had not, in fact, found a new element, but was the first to identify thorium's powerful radioactivity.*TIS

1842 The ﬁrst mutual life insurance company in the U.S. was chartered. Since such companies must employee many actuaries, this provides a good source of jobs for individuals with a knowledge of mathematics. *FFF

In

**1954**, the American Atomic Energy Commission (AEC) began hearings to revoke Robert Oppenheimer's security clearance, thereby severing him from the commission's work. Although he had led the scientists making the atomic bombs during the WW II Manhattan Project, he had been affected by the bombs' death toll and chilling descriptions of radiation sickness. When the Soviet Union detonated an atom bomb in 1949, Edward Teller and Ernest Lawrence lobbied feverishly to develop the hydrogen bomb. Oppenheimer chaired the General Advisory Committee AEC, repudiated the hydrogen bomb as a weapon of “genocide.” In May 1953, when Lewis Strauss accepted the chair of the AEC, he regarded Oppenheimer as a security risk, and wanted him to be dismissed. *TIS

In his testimony, Isador Rabi would say in Oppenheimer's defense: "there he was; he is a consultant, and if you don't want to consult the guy, you don't consult him, period. Why you have to then proceed to suspend clearance and go through all this sort of thing,...We have an A-bomb and a whole series of it, and what more do you want, mermaids? This is just a tremendous achievement. If the end of that road is this kind of hearing, which can't help but be humiliating, I thought it was a pretty bad show. I still think so." *atomicarchive

**1961**In Syracuse, Italy, the scientific festivities began to celebrate the memory of Archimedes who was born in the city in 287 BC and was killed there in 212 BC by a Roman soldier. His last words, according to Livy, were “Nolitangere circulos meos” (Don’t touch my circles). [Scripta Mathematica, 26(1961), 143] *VFR

1961 Yuri Gagarin became the ﬁrst man in space, orbiting the earth in 108 minutes in the Soviet spacecraft Vostok. (or did he... )

1977 Fiji issued a stamp showing a world map in sinusoidal projection. [Scott #374] *VFR

The sinusoidal projection is a pseudocylindrical equal-area map projection, sometimes called the Sanson-Flamsteed or the Mercator equal-area projection. It is defined by:

^{}

The north-south scale is the same everywhere at the central meridian, and the east-west scale is throughout the map the same as that; correspondingly, on the map, as in reality, the length of each parallel is proportional to the cosine of the latitude; thus the shape of the map for the whole earth is the area between two symmetric rotated cosine curves. The true distance between two points on the same meridian corresponds to the distance on the map between the two parallels, which is smaller than the distance between the two points on the map. There is no distortion on the central meridian or the equator. *Wik

1981 HP-41 calculator used in space:

HP-41 calculator used on board NASA's first space shuttle flight. The HP-41 allowed astronauts to calculate the exact angle at which they needed to re-enter the Earth's atmosphere. *CHM

1994, the first Internet spamming program was used by an attorney in Arizona. Laurence Canter created the software program, a simple Perl script, that flooded Usenet message board readers with a notice for the "Green Card Lottery" to solicit business for his law firm of Canter & Siegel (with wife, Martha Siegel.) The reaction from the online community was vigorously critical, condemning such a form of advertising. Thousands of recipients complained, but a new, burgeoning business of unsolicited mass Internet advertising had been spawned. The term "spam" was coined from a sketch in the "Monty Python's Flying Circus" BBC television show in which a waitress offered a menu full of variations of spam to an unwilling patron. *TIS

The Monty Python skit is here.

BIRTHS

1794 Germinal Pierre Dandelin (12 April 1794 – 15 February 1847) was a mathematician, soldier, and professor of engineering. He was born near Paris to a French father and Belgian mother, studying first at Ghent then returning to Paris to study at the École Polytechnique. He was wounded fighting under Napoleon. He worked for the Ministry of the Interior under Lazare Carnot. Later he became a citizen of the Netherlands, a professor of mining engineering in Belgium, and then a member of the Belgian army.

He is the eponym of the Dandelin spheres, of Dandelin's theorem in geometry (for an account of that theorem, see Dandelin spheres), and of the Dandelin–Gräffe numerical method of solution of algebraic equations. He also published on the stereographic projection, algebra, and probability theory.*Wik

1851 Edward Walter Maunder (12 Apr 1851, 21 Mar 1928 at age 76) English astronomer who was the first to take the British Civil Service Commission examination for the post of photographic and spectroscopic assistant at the Royal Observatory, Greenwich. For the next forty years that he worked there, he made extensive measurements of sunspots. Checking historical records, he found a period from 1645 to 1715 that had a remarkable lack of reports on sunspots. Although he might have questioned the accuracy of the reporting, he instead attributed the shortage of report to an actual dearth of sunspots during that period. Although his suggestion was not generally accepted at first, accumulating research has since indicated there are indeed decades-long times when the sun has notably few sunspots. These periods are now known as Maunder minima.*TIS

**1852 Carl Louis Ferdinand von Lindemann**(12 Apr 1852; 6 Mar 1939 at age 86) He showed π is transcendental (

*not the root of any algebraic equation with rational coefficients*), consequently the circle cannot be squared (constructing a square with the same area as a given circle using ruler and compasses alone.) In 1873, Lindemann visited Hermite in Paris and discussed the methods which Hermite had used in his proof that

*e*, the base of natural logarithms, is transcendental. Following this visit, Lindemann was able to extend Hermite's results to show that was also transcendental. *TIS

(the image is of his tombstone.... note the square and circle with Pi inside.)

1903 Jan Tinbergen (April 12, 1903 – June 9, 1994), was a Dutch economist. He was awarded the first Bank of Sweden Prize in Economic Sciences in Memory of Alfred Nobel in 1969, which he shared with Ragnar Frisch for having developed and applied dynamic models for the analysis of economic processes. Tinbergen was a founding trustee of Economists for Peace and Security.

Tinbergen became known for his 'Tinbergen Norm', which is the principle that, if the difference between the least and greatest income in a company exceeds a rate of 1:5, that will not help the company and may be counterproductive.*Wik

DEATHS

1817 Charles Messier (26 Jun 1730, 12 Apr 1817 at age 86)French astronomer who discovered 15 comets. He was the first to compile a systematic catalog of "M objects." The Messier Catalogue (1784), containing 103 star clusters, nebulae, and galaxies. (In Messier's time a nebula was a term used to denote any blurry celestial light source.) He established alphanumeric names for the objects (M1, M2, etc.), which notation continues to be used in astronomy today.*TIS 1919 Friedrich Otto Rudolf Sturm (6 Jan 1841 in Breslau, Germany (now Wrocław, Poland) -12 April 1919 in Breslau, Germany (now Wrocław, Poland)) Sturm wrote extensively on geometry and, other than the teaching textbook on descriptive geometry and graphical statics which we mentioned above and one other teaching text Maxima und Minima in der elementaren Geometrie which he published in 1910, all his work was on synthetic geometry.

He wrote a three volume work on line geometry published between 1892 and 1896, and a four volume work on projective geometry, algebraic geometry and Schubert's enumerative geometry the first two volumes of which he published in 1908 and the second two volumes in 1909. These two multi-volume works collect together most of his life's research. *SAU

**1971**Wolfgang Krull proved the Krull-Schmidt theorem for decomposing abelian groups and defined the Krull dimension of a ring.

1971 Igor Yevgenyevich Tamm (8 Jul 1895, 12 Apr 1971 at age 75)Soviet physicist who shared the 1958 Nobel Prize for Physics with Pavel A. Cherenkov and Ilya M. Frank for his efforts in explaining Cherenkov radiation. Tamm was an outstanding theoretical physicist, after early researches in crystallo-optics, he evolved a method for interpreting the interaction of nuclear particles. Together with I. M. Frank, he developed the theoretical interpretation of the radiation of electrons moving through matter faster than the speed of light (the Cerenkov effect), and the theory of showers in cosmic rays. He has also contributed towards methods for the control of thermonuclear reactions. *TIS George Gamow tells an interesting story about Tamm's unusual math encounter during the Ukraine revolution.

2000 David George Crighton FRS (15 November 1942, Llandudno, Wales - 12 April 2000, Cambridge) was a British mathematician and physicist. In his first paper, Crighton studied the sound wave associated with turbulent flow over a discontinuous surface formed by two semi-infinite flexible planes.

Over the years he worked broadly in the fields of acoustics, equation theory and quasi-diabatic systems including solitons. This included on the generalized Burgers' equation and inverse scattering theory. *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