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Siméon-Denis Poisson
(21 Jun 1781 - 25 Apr 1840)
French mathematician.
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Science Quotes by Siméon-Denis Poisson (5 quotes)
Life is good for only two things: to do mathematics and to teach it.
— Siméon-Denis Poisson
From François Arago, 'Mort de Poisson', Œvres Complètes de François Arago (1854), Vol.2, 662, translated by Webmaster from the original French, “La vie n’est bonne qu’à deux choses: à faire des mathématiques et à les professer.” Quote introduced by Arago as “Poisson … avait l’habitude de dire” (“Poisson … used to say”). Also seen in a book of quotes, Alphonse Rebière (ed.), Mathématiques et Mathématiciens: Pensées et Curiosités (1893), 158, as “La vie n’est bonne qu'à étudier et à enseigner les mathématiques”, which Webmaster translates as “Life is good only to study and to teach mathematics”. Also currently found online as “La vie n’est bonne que pour deux choses: découvrir les mathématiques et enseigner les mathématiques”, translated as “Life is good for only two things, discovering mathematics and teaching mathematics”, in Howard Whitley Eves, Mathematical Circles Adieu: A Fourth Collection of Mathematical Stories and Anecdotes (1977), 22. Arago was a contemporary of Poisson, and Webmaster speculates from the context of the biography that perhaps Arago knew the quote firsthand from Poisson. Webmaster has not yet been able to trace either version to a primary source written by Poisson. (Can you help?)
That which can affect our senses in any manner whatever, is termed matter.
— Siméon-Denis Poisson
Opening sentence of English edition, Siméon-Denis Poisson and Henry Hickman Harte (trans.), 'Introduction', A Treatise of Mechanics (1842), Vol. 1, 1. From the original French, “La matière est tout ce qui peut affecter nos sens d’une manière quelconque.”, in 'Introduction', Traité de Mécanique (2nd Ed., 1833), Vol. 1, 1. This definition does not appear in the 1st ed. (1811).
The measure of the probability of an event is the ratio of the number of cases favourable to that event, to the total number of cases favourable or contrary, and all equally possible, or all of which have the same chance.
— Siméon-Denis Poisson
In 'Règles générales des probabilités', Recherches sur la Probabilités des Jugemens (1837), Chap. 1, 31, as translated in George Boole, An Investigation of the Laws of Thought (1854), 244. From the original French, “La mesure de la probabilité d'un événement, est le rapport du nombre de cas favorables à cet événement, au nombre total de cas favorables ou contraires, et tous également possibles, ou qui ont tous une même chance.”
The probability of an event is the reason we have to believe that it has taken place, or that it will take place.
— Siméon-Denis Poisson
In 'Règles générales des probabilités', Recherches sur la Probabilités des Jugemens (1837), Chap. 1, 30, as translated in George Boole, An Investigation of the Laws of Thought (1854), 244. From the original French, “La probabilité d’un événement est la raison que nous avons de croire qu’il aura ou qu’il a eu lieu.”
Things of all kinds are subject to a universal law which may be called the law of large numbers. It consists in the fact that, if one observes very considerable numbers of events of the same nature, dependent on constant causes and causes which vary irregularly, sometimes in one direction, sometimes in the other, it is to say without their variation being progressive in any definite direction, one shall find, between these numbers, relations which are almost constant.
— Siméon-Denis Poisson
Poisson’s Law of Large Numbers (16 Nov 1837), in Recherches sur la Probabilités (1837), 7. English version by Webmaster using Google Translate, from the original French, “Les choses de toutes natures sont soumises à une loi universelle qu’on) peut appeler la loi des grands nombres. Elle consiste en ce que, si l’on observe des nombres très considérables d’événements d’une même nature, dépendants de causes constantes et de causes qui varient irrégulièrement, tantôt dans un sens, tantôt daus l’autre, c’est-à-dire sans que leur variation soit progressive dans aucun sens déterminé, on trouvera, entre ces nombres, des rapports a très peu près constants.”
Quotes by others about Siméon-Denis Poisson (2)
A distinguished writer [Siméon Denis Poisson] has thus stated the fundamental definitions of the science:
“The probability of an event is the reason we have to believe that it has taken place, or that it will take place.”
“The measure of the probability of an event is the ratio of the number of cases favourable to that event, to the total number of cases favourable or contrary, and all equally possible” (equally like to happen).
From these definitions it follows that the word probability, in its mathematical acceptation, has reference to the state of our knowledge of the circumstances under which an event may happen or fail. With the degree of information which we possess concerning the circumstances of an event, the reason we have to think that it will occur, or, to use a single term, our expectation of it, will vary. Probability is expectation founded upon partial knowledge. A perfect acquaintance with all the circumstances affecting the occurrence of an event would change expectation into certainty, and leave neither room nor demand for a theory of probabilities.
“The probability of an event is the reason we have to believe that it has taken place, or that it will take place.”
“The measure of the probability of an event is the ratio of the number of cases favourable to that event, to the total number of cases favourable or contrary, and all equally possible” (equally like to happen).
From these definitions it follows that the word probability, in its mathematical acceptation, has reference to the state of our knowledge of the circumstances under which an event may happen or fail. With the degree of information which we possess concerning the circumstances of an event, the reason we have to think that it will occur, or, to use a single term, our expectation of it, will vary. Probability is expectation founded upon partial knowledge. A perfect acquaintance with all the circumstances affecting the occurrence of an event would change expectation into certainty, and leave neither room nor demand for a theory of probabilities.
An Investigation of the Laws of Thought (1854), 243-244. The Poisson quote is footnoted as from Recherches sur la Probabilité des Jugemens.
Ohm found that the results could be summed up in such a simple law that he who runs may read it, and a schoolboy now can predict what a Faraday then could only guess at roughly. By Ohm's discovery a large part of the domain of electricity became annexed by Coulomb's discovery of the law of inverse squares, and completely annexed by Green's investigations. Poisson attacked the difficult problem of induced magnetisation, and his results, though differently expressed, are still the theory, as a most important first approximation. Ampere brought a multitude of phenomena into theory by his investigations of the mechanical forces between conductors supporting currents and magnets. Then there were the remarkable researches of Faraday, the prince of experimentalists, on electrostatics and electrodynamics and the induction of currents. These were rather long in being brought from the crude experimental state to a compact system, expressing the real essence. Unfortunately, in my opinion, Faraday was not a mathematician. It can scarely be doubted that had he been one, he would have anticipated much later work. He would, for instance, knowing Ampere's theory, by his own results have readily been led to Neumann’s theory, and the connected work of Helmholtz and Thomson. But it is perhaps too much to expect a man to be both the prince of experimentalists and a competent mathematician.
From article 'Electro-magnetic Theory II', in The Electrician (16 Jan 1891), 26, No. 661, 331.
See also:
- 21 Jun - short biography, births, deaths and events on date of Poisson's birth.