Blaise Pascal
According to the magnificent and rich (for those that like Blaise Pascal and are unterested by his life and works)
WEB site : http://www.groups.dcs.st-and.ac.uk/ (Article by J J O'Connor and E F Robertson) from the School of Mathematics and Statistics University of St Andrews, Scotland
Born : 18 June 1623 in Clermont (now Clermont-Ferrand), Auvergne, France.
Died : 19 August 1662 in Paris, France.
«Blaise Pascal was the third of Etienne Pascal's children and his only son. Blaise's mother died when he was only three years old. In 1632 the Pascal family, Etienne and his four children, left Clermont and settled in Paris. Blaise Pascal's father had unorthodox educational views and decide to teach his son himself. Etienne Pascal decided that Blaise was not to study mathematics before the age of 15 and all mathematics texts were removed from their house. Blaise however, his curiosity raised by this, started to work on geometry himself at the age of 12. He discoverd that the some of the angles of a triangle are two right angles and, when his father found out, he relented and allowed Blaise a copy of Euclid.»
«At the age of 14 Blaise Pascal started to accompagny his father to Mersenne's meetings. Mersenne belonged to the religious order of Minims, and his cell in Paris was a frequent meeting place for Gassendi, Roberval, Carcavi, Auzout, Mydorge Desargues and others. Soon, certainly by the time he was 15, Blaise came to admire the work of Desargues. Ad the age of sixteen, Pascal presented a single piece of paper to one of Mersenne's meeting in June 1639. It contained a number of projective geometry theorems, including Pascal's mystic hexagon.»
«In December 1639 the Pascal family left Paris to live in Rouen where Etienne had been appointed as a tax collector for Upper Normandy. Shortly after settling in Rouen, Blaise had his first work, Essay on Conic Sections published in February 1640.»
«Pascal invented the first digital calculator to help his father with his work collecting taxes. He worked on it for three years between 1642 and 1645. The device, called the Pascaline, ressembled a mechanical calculator of the 1940s. This, almost certainly, makes Pascal the second person to invent a mechanical calculator for Schickard had manufactured one in 1624....»
«Events of 1646 were very significant for the young Pascal. In that year his father injured his leg and had to recuperate in his house. He was looked after by two brothers from a religious movement just outside Rouen. They had a profound effect on the young Pascal and he became deeply religious.»
«From about this time Pascal began a series of experiments on atmospheric pressure. By 1647 he had proved to his satisfaction that a vacuum existed. Descartes visited Pascal on 23 September. His visit only lasted two days and the two argued about the vacuum which Descartes did not beleive in. Descartes wrote, rather cruelly to Huygens after this visit that Pascal ... has too much vacuum in his head.»
«In August of 1648 Pascal observed that the pressure of the atmosphere decreases with height and deduce that a vacuum existed above the atmosphere. Descartes wrote to Carcavi in June 1647 about Pascal's experiments saying : It was I who two years ago advised him to do it, for although I have not performed it myself, I did not doubt of its success...»
«In October 1647 Pascal wrote New Experiments Concerning Vacuums which led to disputes with a number of scientifics who, like Descartes, did not believe in a vacuum.»
«Etienne Pascal died in September 1651 and following this Blaise wrote to one of his sisters giving a deeply Christian meaning to death in general and his father's death in particular. His ideas here were to form the basis for his later philosophical work Pensées.»
«From May 1653 Pascal worked on mathematics and physics writing Treatise on the Equilibrium of Liquids (1653) in which he explains Pascal's law of pressure ... He worked on conic sections and produce important theorems in projective geometry. In The Generation of Conic Sections (mostly completed by March 1648 but worked on again in 1653 and 1654) Pascal considered conics generated by central projection of a circle. This was meant to be the first part of a treatise on conics which Pascal never completed. The work is now lost but Leibnitz and Tschimhaus made notes from it and it is though these notes that a fairly complete picture of this work is now possible.»
«Althought Pascal was not the first to study the Pascal triangle, his work on the topic in Treatise on the Arithmetical Triangle was the most important on this topic and, through the work of Wallis, Pascal work on binomial coefficients was to lead Newton to his discovery of the general binomial theorem for fractional and negative powers.»
«In correspondence with Fermat he laid the foundation for the theory of probability. This correspondence consisted of five letters and occured in the summer of 1654 ... »
«However, despite his health problems, he worked intensely on scientifics and mathematical questions until October 1654. Sometimes around then he nearly lost his life in an accident. The horse pulling his carriage bolted and the carriage was left hanging over a bridge above the river Seine. Although he was rescued without any physical injury, it does not appear that he was much affected psychologically. Not long after he hunderwent another religious experience, on 23 November 1654, and he pledged his life to Christianity.»
«After this time Pascal made visits to the Jansenist monastery of Port-Royal des Champs about 30 km south west of Paris. He began to publish anonymous works on religious topics, eighteen Provincial Letters being published during 1656 and early 1657. These were written in defense to his friend Antoine Arnauld, an opponent of the Jesuits and a defender of Jansenism, who was on trial before the faculty of theology in Paris for his controversial religious works. Pascal most famous work in philosophy is Pensée, a collection of personnal thoughts on human suffering and faith in God which he began in late 1656 and continued to work on during 1657 and 1658. This work contains "Pascal's wager" which claims to prove that beleive in Gold is rational with the following argument : If God does not exist, one whill lose nothing by believing in him, while if he does exist, one lose everything by not beleving ... we are compelled togamble...»
«His last work was on the cycloid, the curve traced by a point on the circumference of a rolling circle. In 1658 Pascal started to think about mathematical problems again as he lay awake at night unable to sleep for pain... Pascal died at the age of 39 in intense pain after a malignant growth in his stomach spread to the brain ...»
WEB site : http://www.groups.dcs.st-and.ac.uk/ (Article by J J O'Connor and E F Robertson) from the School of Mathematics and Statistics University of St Andrews, Scotland
And now in :
Dictionary of Scientific Biography (New York 1970-1980)
we find the following judgment :
«At once a physicist, a mathematician, an eloquent publicist in the Provinciales ... Pascal was embarrassed by the very abundance of his talents. It has been suggested that it was his too concrete turn of mind that prevented his discovering the infinitesimal calculus, and in some of the Provinciales the misterious relations of human beings with God are treated like as if they were a geometrical problem. But these considerations are far outweighed by the profit that he drew from the multiplicity of his gifts, his wrintings are rigorous because of his scientific training ...»
Finally do quote, in french for respect of Pascal's beautiful language, the following passage of Pensées «Œuvres complètes de Pascal, Pensées», p.1091 à 1093 (La Pléiade, GALIMARD, Paris 1954) :
«L'ESPRIT DE GEOMETRIE ET L'ESPRIT DE FINESSE
21.[405] Différence entre l'esprit de géométrie et l'esprit de finesse. - En l'un, les principes sont palpables, mais éloignés de l'usage commun ; de sorte qu'on a peine à tourner la tête de ce côté-là, manque d'habitude : mais, pour peu qu'on l'y tourne, on voit les principes à plein ; et il faudrait avoir tout à fait l'esprit faux pour mal raisonner sur des principes si gros qu'il est presque impossible qu'ils échappent.»
«Mais, dans l'esprit de finesse, les principes sont dans l'usage commun et devant les yeux de tout le monde. On n'a que faire de tourner la tête ni de se faire violence ; il n'est question que d'avoir bonne vue, mais il faut l'avoir bonne ; car les principes sont si déliés et en si grand nombre, qu'il est presque impossible qu'il n'en échappe. Or, l'omission d'un principe mène à l'erreur ; ainsi il faut avoir la vue bien nette pour voir tous les principes, et ensuite l'esprit juste pour ne pas raisonner faussement sur des principes connus.»
«Tous les géomètres seraient donc fins s'ils avaient la vue bonne, car ils ne raisonnent pas faux sur les principes qu'ils connaissent ; et les fins seraient géomètres s'ils pouvaient plier leur vue vers les principes inaccoutumés de géométrie.»
Blaise Pascal