Pierre-Simon Laplace

Pierre -Simon ( Marquis de ) Laplace (* March 28, 1749 in Beaumont -en-Auge in Normandy; † March 5, 1827 in Paris) was a French mathematician, physicist and astronomer. He worked among others with the probability theory and differential equations.

Life

Youth

Laplace was born the son of a wealthy farmer and cider merchant. The occupation of father secured the family a relatively comfortable life. From the age of seven until his sixteenth year Laplace attended as a day student, the school of the Benedictine order in place. After the school children of the third estate beat normally an a military or ecclesiastical life. The father of Laplace wished for his son a spiritual career and so Laplace studied from 1766 theology and philosophy at the Jesuit college at Caen. There he made ​​the acquaintance of professors Christoph Gadblet (1734-1782) and Pierre Le Canu, who recognized his talent for mathematics and opened his eyes for mathematics.

Career

In 1768 he left Caen and therefore went to Paris with a letter to Jean -Baptiste le Rond d' Alembert, the then most famous mathematician of France, to study mathematics at him. As Laplace made ​​representations to d' Alembert, this gave him a math problem and a week of time to solve this. Laplace it solved overnight and knocked on the next day again to d' Alembert door. Then he gave him a more difficult problem, but the Laplace solved in the same time. It is not certain whether this incident has really happened, sure, however, that d' Alembert was very impressed by Laplace and supported him and encouraged. To secure its financial situation, gave d' Alembert Laplace in 1771 a position as a teacher of geometry, trigonometry, elementary calculus and statistics at the Paris Military Academy. To be received from 1770 to 1773 wrote Laplace 13 important essays on different and difficult issues to extreme value problems, astro mechanics, differential equations, probability and game theory, as well as the integral calculus to gain reputation and at the Paris Academy of Sciences. Laplace applied in 1771 and 1772 at the Académie, but was rejected in favor of older applicants. Despite the age difference Laplace met this deep, especially in 1772, as Laplace 's mathematical abilities much higher than that of its competitors panelist ( cousin ). Ever Laplace was relatively immodest. D' Alembert wrote it early in 1773 a letter to Lagrange, who was then staying in Berlin to find out whether there exists the possibility of a post and a place at the Prussian Academy of Sciences for Laplace. Laplace would be almost become a German scientist. However, this letter was superfluous as Laplace in 1773 at the age of just 24 years was admitted as Adjunkter at the Académie française. In the following years, Laplace increased its scientific reputation steadily and became one of the most important and influential scientists. But suffered from his relationship with his colleagues. So, for example, felt d' Alembert, that the work of Laplace made ​​a big part of his own life's work obsolete. 1784 Laplace examinateur for the Royal Artillery, which was at that time a responsible budget since the candidates whose suitability Laplace considered, came almost exclusively from a very good family and found his reports to highest authorities attention. In this role, he tested in 1785 the then sixteen -year-old Napoleon Bonaparte. In April of that year, Laplace was a regular member of the Académie des sciences.

Family and the French Revolution

1788 married Laplace twenty years younger Marie- Charlotte de Courty de Romanges ( born October 8, 1769 in Besançon ( Doubs), † July 20, 1862 in Paris). She later gave birth to him a year a son, Charles- Emile Laplace (1790-1874), the General was later. 1792 was their daughter Sophie -Suzanne Laplace ( 1792-1813 ) to the world. During the French Revolution, Laplace was able to continue his research largely and in 1792 a member of the Committee on Weights and Measures, which provided for the later introduction of the units are in meters and kilograms. This office had to Laplace but in December of the year to give up, just like his other activities, since the reign of Robespierre was the participation in the revolution and hatred of the monarchy condition for work. Laplace fled with his family from the reign of terror of the Jacobins in the 50 km south-east of Paris lying Melun.

After Robespierre died on July 28, 1794 even through the guillotine, Laplace returned to Paris and was polytechnique in December of the year one of the two Examinateure for the École. 1795 Laplace took his work in the Committee of Weights and back on and was its chairman. In the same year, the Academy was re-established with the umbrella organization of the Institut de France. Laplace was a founding member and was vice president of the Institute. Five months later, he became its President. In addition, he took over the management of the Paris Observatory and the research area.

Interior Minister Napoleon

At the same time he made ​​first relations with Napoleon, so he supposed, was interior minister at his own request after his coup in 1799. However, a position he knew it so bad that it was already after six weeks replaced by Napoleon's brother, Lucien. To comfort him, Napoleon made a member of the relatively less influential Senate. In 1803 Laplace Vice- President of the Senate, and thus a rich man. Due to the multitude of his offices he earned 100,000 francs a year, which was a more than hefty sum at the time. For comparison: in 1810 earned Gaussian as head of the Göttingen observatory about 4,000 francs.

After Laplace in 1804 voted in the Senate for the establishment of Napoleon as Emperor knighted him in 1806 for the Count. In the same year moved to Arcueil Laplace, a suburb of Paris, in the house next door of the chemist Berthollet Claude Louis. With this, he founded the Société d' Arcueil, in which carried out the two other, mostly young scientists, experiments. The scholars among others, Jean -Baptiste Biot and Alexander von Humboldt belonged. Through this work, but he made enemies because he laid down a clear research program, which mainly included its own research priorities, and this also did mercilessly. An additional prestige lost Laplace, because he still clung to the particle nature of light, while the wave theory was increasingly recognized by Augustin Jean Fresnel. 1813 his daughter died in childbirth, gave Laplace, however, a granddaughter. From her all the modern-day descendants of Laplace come from since, although his son was 85 years old, but died childless. Other opponents is created Laplace, when he voted for the deposition of Napoleon in 1814 and at once put the Bourbon restoration available. King Louis XVIII. however, Laplace made ​​in gratitude to peer of France in 1815 and 1817 to the Marquis ( Marquis ). 1816 Laplace put his work at the École polytechnique down and became a member of the 40 immortals of the Académie Française. 1826 enacted the king a tougher press law, subject to the many scientists with signatures to the field. Laplace lost its last political friends when he tried to take colleagues for the law. Because of his ability to always be on the side of the powerful, Laplace was not buried after his death, in spite of great scientific achievements in the Panthéon, but at the Paris cemetery.

Work

Laplace's greatest scientific work is in the field of astronomy, or more precisely of celestial mechanics. From 1799 to 1823 he wrote his Traité de Mécanique Céleste major work (Treatise on Celestial Mechanics ). This five-volume book was published in German under the name of celestial mechanics. In it he gives an overview of all findings since Newton, as well as his own research and proves to be perfecter of Newton. He gives a theoretical proof of the stability of planetary orbits. Due to irregularities in the orbits one time was of the opinion that the solar system could collapse. He also postulated the existence of black holes and deals with the three-body problem. Although the work is mathematically very demanding and therefore very difficult to read, it was in the subsequent period required reading for all aspiring astronomers.

Laplace presented his book to the First Consul Napoleon. It is a conversation, the text is, however, preserved in numerous variations revealed. The French astronomer Hervé Faye is quoted as follows:

" Comme le citoyen Laplace présentait au général Bonaparte la première édition de son Exposition du Système du monde, le général lui dit: " Newton a parlé de Dieu dans son livre. J'ai déjà parcouru le vôtre et je n'y ai pas trouvé ce nom une seule fois. À quoi Laplace aurait répondu: " Citoyen premier Consul, depending n'ai pas eu besoin de cette hypothèse. »»

" When the Civil Laplace showed the first edition of his Exposition du Système du monde general Bonaparte, the general said to him," Newton said in his book of God. I have theirs already looked through and found this term not once " Whereupon Laplace had replied: ". Citizens and First Consul, I have been no need of this hypothesis " ."

This conversation was seen by many as an expression of a radical atheism. You may, however, Laplace meant by his answer something else. Newton had postulated an organizing function of God in his work. God should regularly intervene in the mechanical world events to the secular perturbations, which are increasingly brought it into disorder and threatened to destroy virtually to put back into place. Since Newton, however, was the celestial mechanics more advanced and Laplace could explain such disturbances and calculate to try without an ordering God. Therefore, the response of Laplace 's probably not meant to be complete denial of the existence of God.

The work was a comprehensive in its time compilation of knowledge about celestial mechanics, which was still 50 years later regarded as largely complete. Already in 1796, three years before the first two volumes of celestial mechanics, Laplace published the Exposition du Systems du monde ( representation of the world system ). This also five-volume book is a kind of non- mathematical introduction to celestial mechanics. Laplace is in the astronomical world view of his time, and proves that the probability of collision of a comet with the earth, in the course of astronomical periods, however, is small in size. In the last band and last chapter of the work of Laplace developed at 19 pages a theory about the origin of the solar system, known as the nebular hypothesis today.

In 1799 he put forward the hypothesis that on the back of the moon would have a larger " bump " exist that affects the motion of the moon. A recent publication shows that this consideration might be right.

The second major area of ​​research was the Laplace probability. For Laplace they figured a way to come despite the lack of knowledge about certain results. In his two-volume work Théorie Analytique the probabilites (1812 ) Laplace gave a definition of probability and dealt with dependent and independent events, especially in connection with gambling. He also treated in the book the expectation value, mortality rates and life expectancy. The work presented a refutation of the thesis that a rigorous mathematical treatment of probability was not possible. This thesis was then held by many mathematicians and also Laplace's former teacher d' Alembert was, until his death in 1783 this view.

Two years later, the book Essai Philosophique sur appeared the probabilites ( Philosophical Essay on the probability). This work was how the Exposition du Systems du monde, written for a wide audience, the reader, however, spared only the formulas and was sometimes easier in any way. In addition to the themes of the Théorie Analytique Laplace described also detected an all rational " world spirit " who knows the present with all the details and can therefore describe the past and future of world events in detail. However, Laplace also thought that human intelligence could never achieve this. This " world spirit " later became known as Laplace demon and caused fierce opposition among the philosophers, because he embodies a perfect determinism, which excludes any free will.

The completely deterministic world view is not compatible with the findings of modern quantum mechanics and their statistical interpretation (for example, Born's probability interpretation). Some physicists were able to with this statistical interpretation of quantum mechanics does not accept and talked to a certain extent on the Laplacian determinism. The best known is certainly the skeptical saying Einstein's " God does not play dice ." The question of a universal determinism is still unclear (see determinism ).

1780 made ​​with Laplace Lavoisier Experiments with an ice calorimeter: They confirmed the equivalence of animal respiration with the combustion of charcoal - in both cases is burned by oxygen carbon to carbon dioxide. Is interesting to note the assessment of chance: The experimenters hypothesized that the fluctuations in the experiment would in principle eliminate, if you only knew all the conditions of the experiment ( see also determinism ).

Laplace was always more physicists than mathematicians. The mathematics served him only as a means to an end. Today, however, the mathematical method, the Laplace developed and anwandte, much more important than the actual work itself. The most important are the Laplace history record, the Laplace operator, Laplace's equation, and the Laplace transform.

Honors

He is immortalized in particular on the Eiffel Tower, see: The 72 names on the Eiffel Tower.

According to Pierre- Simon Laplace different surface structures on the moon was named, for example, the promontory Laplace and the moon crater Laplace. The asteroid ( 4628 ) Laplace is also named after him.

Editions

Monographs:

• " Exposition du système du monde ", first edition in two volumes, Paris 1796; last revised by Laplace and posthumous 6th edition, Paris 1836; revised edition of the 6th edition, Fayard, France in 1984, re-edited from the edition of 1799 by the Cambridge University Press, 2009.
• " Traité de mécanique Céleste ," five volumes, Paris 1798-1825 ( reprint, Brussels 1967).
• " Théorie analytique the probabilites ", Paris 1812 ( reprint, Brussels 1967).
• " Essai Philosophique sur les probabilites ", Paris 1814 ( reprint, Brussels 1967). The essay is a subsequently written introduction to the Théorie analytique the probabilites and was both separately as edited Analytique also related to the Théorie.
• " Précis de l' histoire de l' astronomy ", Paris 1821, 2nd edition 1863. The outline of the history of astronomy is the final book Exposition du système V du monde.
• " Correspondance de PIERRE SIMON LAPLACE ", ed. By Roger Hahn ( posthumously ), two volumes, Turnhout, 2013.

German translations:

• "Representation of the world system ", by Johann Karl Friedrich Hauff, Frankfurt 1797; Hauff's translation is based on the French edition, so that Laplace's subsequent revisions are not received in the translation. Heinrich Schmidt has published the chapter on cosmogony of the exposure along with the cosmogony theory of Kant: " The Kant-Laplace theory ideas to the world development of Immanuel Kant and Pierre Laplace ", Leipzig, 1925.
• "Representation of the world system, Volume 1, Books 1-3: From the apparent motion of celestial bodies / Of the true motion of the heavenly bodies / Of the laws of motion ", translated by Manfred Jacobi, Franz Kerschbaum, Ostwald's Classics series, vol 301, Harri German, 2008, ISBN 978-3-8171-3301-7
• "Representation of the world system Volume 2, Books 4-5: From the theory of universal gravitation / outline of the history of astronomy ", translated by Manfred Jacobi, Franz Kerschbaum, Ostwald's Classics series, vol 302, Harri German, 2008, ISBN 978 - 3-8171-3302-4
• " Celestial mechanics ", by Johann Carl Burckhardt, Berlin 1800-1802. Burckhardt's translation comprises the first two volumes of the Mécanique Céleste.
• " Philosophical Essay on Probability ," ed. by Richard von Mises, Leipzig 1932, 2nd edition, Frankfurt 1996.

In addition, there are two editions of her work:

• " Oeuvre ", eight volumes, Paris 1843-1847;
• " Oeuvres Completes ", fourteen volumes, Paris 1878-1912, ed. of the Académie des sciences. This issue is relevant today.