Pierre-Simon Laplace

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Pierre-Simon Laplace (19th century painting)
Laplace (19th century engraving)

Pierre-Simon (Marquis de) Laplace (born March 28, 1749 in Beaumont-en-Auge in Normandy , † March 5, 1827 in Paris ) was a French mathematician , physicist and astronomer . Among other things, he dealt with probability theory and differential equations .



Laplace was born the son of a wealthy farmer and cider trader. The father's job ensured the family a relatively comfortable life. From the age of seven to sixteen, Laplace attended the local Benedictine school as a day pupil . After completing school, Third Estate children usually embarked on a military or ecclesiastical path. Laplace's father wanted his son to have a spiritual career and so from 1766 Laplace studied theology and philosophy at the Jesuit College of Caen . There he made the acquaintance of professors Christoph Gadblet (1734–1782) and Pierre Le Canu , who recognized his mathematical talent and opened his eyes to mathematics.


In 1768 he therefore left Caen and went to Paris with a letter of recommendation to Jean-Baptiste le Rond d'Alembert , the most famous mathematician in France at the time, to study mathematics with him. When Laplace approached d'Alembert, the latter gave him a math problem and a week to solve it. Laplace solved it overnight and knocked again on d'Alembert's door the next day. The latter then gave him a more difficult problem, which Laplace solved in the same time. It is not certain whether this incident really happened, but what is certain is that d'Alembert was very impressed by Laplace and supported and encouraged him. In order to secure his financial situation, d'Alembert gave Laplace a position as a teacher of geometry , trigonometry , elementary analysis and statistics at the Paris Military Academy in 1771 . From 1770 to 1773 Laplace wrote 13 important treatises on different and difficult topics, on extreme value problems , astromechanics, differential equations , probability and game theory , as well as on integral calculus, in order to gain reputation and be accepted at the Paris Académie des Sciences . Laplace applied to the Académie in 1771 and 1772, but was turned down in favor of older applicants. Despite the age difference, this hit Laplace deeply, especially in 1772, as Laplace rated his math skills much higher than those of his competitor (cousin). In general, Laplace was relatively arrogant. At the beginning of 1773 D'Alembert wrote a letter to Lagrange , who was in Berlin at the time, to find out whether there was a possibility of a post and a place at the Prussian Academy of Sciences for Laplace. This letter became superfluous when Laplace was accepted as an adjunct at the Académie française in 1773 at the age of just 24 . In the following years Laplace increased his scientific reputation steadily and became one of the most important and influential scientists. But his relationship with his colleagues suffered as a result. For example, d'Alembert felt that Laplace's work was rendering a large part of his own life's work obsolete. In 1784 Laplace became an examiner for the Royal Artillery, which at that time was a responsible post, since the candidates whose suitability Laplace examined came almost exclusively from a very good family and his reports received high attention. In this function he also examined the then sixteen-year-old Napoleon Bonaparte in 1785 . In April of that year, Laplace became a full member of the Académie des sciences .

Family and French Revolution

In 1788 Laplace married Marie-Charlotte de Courty de Romanges, who was twenty years his junior (born October 8, 1769 in Besançon ( Doubs ), † July 20, 1862 in Paris ). A year later she gave birth to a son, Charles-Emile Laplace (1790–1874), who later became a general. In 1792 their daughter Sophie-Suzanne Laplace (1792–1813) was born. During the French Revolution , Laplace was able to continue his research as far as possible and in 1792 became a member of the Committee for Weights and Measures, which later introduced the units of meters and kilograms . Laplace had to give up this office in December of that year, just like his other activities, since with Robespierre's rule, participation in the revolution and hatred of the monarchy became a condition for his work. Laplace and his family fled from the Jacobin reign of terror to Melun, 50 kilometers southeast of Paris .

After Robespierre himself had found death by the guillotine on July 28, 1794, Laplace returned to Paris and became one of the two examiners for the École polytechnique in December of that year . In 1795 Laplace resumed his work on the Weights and Measures Committee and became its chairman. In the same year the academy was re-established with the umbrella organization Institut de France . Laplace was a founding member and became vice president of the institute. Five months later he became its president. He also took over the management of the Paris Observatory and the research area.

Minister of the Interior of Napoleon

At the same time he established his first relationships with Napoleon , so that after his coup d'état in 1799 , allegedly at his own request, he became Minister of the Interior. However, he performed this office so badly that he was replaced after just six weeks by a brother of Napoleon, Lucien . As a consolation, Napoleon made him a member of the relatively ineffective Senate. In 1803 Laplace became Vice President of the Senate, making him a wealthy man. Due to the large number of his offices he earned 100,000 francs a year, which was a very large sum at the time. For comparison: in 1810 Gauss earned around 4,000 francs as head of the Göttingen observatory.

After Laplace had voted in the Senate in 1804 to appoint Napoleon as emperor, he ennobled him to count in 1806. In the same year Laplace moved to Arcueil , a suburb of Paris, in the neighboring house of the chemist Claude-Louis Berthollet . With this he founded the Société d'Arcueil , in which the two carried out experiments with other, mostly young scientists. These scientists included Jean-Baptiste Biot and Alexander von Humboldt , among others . Through this work, however, he made enemies, as he set up a clear research program, which mainly included his own research interests, and carried it out mercilessly. Laplace lost further prestige because he continued to cling to the particle nature of light, while the wave theory gained more and more recognition through Augustin Jean Fresnel . In 1813 his daughter died in childbed, but Laplace gave birth to a granddaughter. All of Laplace's descendants today descend from her, as his son was 85 years old but died childless. Laplace created further opponents when he voted for the deposition of Napoleon in 1814 and immediately made himself available to the Bourbon restoration. King Louis XVIII on the other hand, as a thank you, Laplace made Peer of France in 1815 and Marquis (margrave) in 1817 . In 1816 Laplace laid down his work at the École polytechnique and became a member of the 40 Immortals of the Académie française . In 1822 he was elected to the American Academy of Arts and Sciences . In 1826 the king issued a stricter press law, against which many scientists took action with signatures. Laplace lost his last political friends when he tried to win colleagues for the law. Because of his ability to always be on the side of the mighty, Laplace was not buried in the Panthéon after his death, despite great scientific successes , but in the Paris cemetery.


Laplace's greatest scientific work is in the field of astronomy or, more precisely, celestial mechanics. From 1799 to 1823 he wrote his main work Traité de Mécanique Céleste (treatise on celestial mechanics). This five-volume book was published in German under the name Himmelsmechanik . In it he gives an overview of all knowledge gained since Newton as well as of his own research and proves himself to be Newton's accomplisher. It gives mathematical proof of the stability of the planetary orbits . Due to irregularities in the trajectories, it was believed at the time that the solar system could collapse. He also postulates 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 became compulsory reading for all budding astronomers in the period that followed.

Laplace presented his book to the First Consul Napoleon Bonaparte. This resulted in a conversation, the wording of which has been handed down in numerous variations. The French astronomer Hervé Faye quoted it 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, je n'ai pas eu besoin de cette hypothèse.' »

“When the citizen Laplace showed General Bonaparte the first edition of his Exposition du Système du monde , the General said to him: 'Newton spoke of God in his book. I have already looked through yours and have never found this term. ' To which Laplace replied: 'Citizen and First Consul, I did not need this hypothesis.' "

- Hervé Faye : Sur l'origine du monde, théories cosmogoniques des anciens et des modern (1884)

This conversation was seen by many as an expression of radical atheism . Laplace probably meant something else by his answer. Newton had postulated an ordering function of God in his work. God should intervene regularly in the mechanical world events in order to correct the secular disturbances , which are increasingly causing disorder and threatening to destroy it. Since Newton, however, celestial mechanics had advanced further and Laplace was able to explain and calculate such disturbances without using an ordering god. Therefore, Laplace's answer is probably not to be understood as a complete negation of the existence of God.

The work was a comprehensive compilation of the knowledge of celestial mechanics at the time, which was still considered largely complete 50 years later. As early as 1796, three years before the first two volumes of Celestial Mechanics , Laplace published the Exposition du systeme du monde (Representation of the World System). This five-volume book is to a certain extent a non-mathematical introduction to celestial mechanics . Laplace reproduces the astronomical worldview of his time and proves that the probability of a comet colliding with the earth is only small, but great over the course of astronomical time. In the last volume and last chapter of the work, Laplace develops a 19-page theory about the formation of the solar system, which is known today as the nebular hypothesis .

In 1799 he hypothesized that there must be a larger "bump" on the back of the moon that affects the movement of the moon.

Laplace's second major area of ​​research was probability . For Laplace it represented a way out to get certain results despite a lack of knowledge. In his two-volume work Théorie Analytique des Probabilités (1812), Laplace gave a definition of probability and dealt with dependent and independent events , especially those related to gambling. He also covered expected value , mortality, and life expectancy in the book . The work represented a refutation of the thesis that a strict mathematical treatment of probability is not possible. This thesis was advocated by many mathematicians at the time, and Laplace's former teacher d'Alembert was of this opinion until his death in 1783.

Two years later, the book Essai philosophique sur les Probabilités was published (Philosophical essay on probability). Like the Exposition du systeme du monde , this work was written for a broad readership, but only spared the reader the formulas and was in no way easier. In addition to the topics of the Théorie Analytique , Laplace also described a “world spirit” that grasps everything rationally, knows the present with all the details and can therefore describe the past and future of world events in all details. Laplace, however, also said that human intelligence could never achieve this. This "world spirit" later became known as the Laplace demon and caused bitter conflict over the question of whether such an embodied, perfect determinism was compatible or incompatible with free will (see Compatibilism and Incompatibilism ).

The completely deterministic world view is often seen as incompatible with statistical interpretations of modern quantum mechanics (e.g. Born's probability interpretation ). Some physicists could not get used to the fundamentally indeterministic character of microscopic natural processes. The best known is probably Einstein's skeptical saying “ God does not roll the dice ”. The question of an all-embracing determinism is still unanswered (see determinism ).

In 1780, Laplace and Lavoisier made experiments with an ice calorimeter : They confirmed the equivalence of animal respiration with the combustion of charcoal - in both cases, oxygen is used to burn carbon to carbon dioxide . The assessment of chance seems interesting : The experimenters assumed that the fluctuations in the experiment could in principle be eliminated if one only knew all the conditions of the experiment ( see also determinism ).

Laplace was always more of a physicist than a mathematician. Mathematics served him only as a means to an end. Today, however, the mathematical procedures that Laplace developed and used are much more important than the actual work itself. The most important are the Laplace expansion theorem , the Laplace operator , the Laplace equation and the Laplace transform .


His name is immortalized on the Eiffel Tower, see: The 72 names on the Eiffel Tower .

Various surface structures on the moon have been named after Pierre-Simon Laplace , e. B. the promontory Laplace and formerly a moon groove . The asteroid (4628) Laplace is also named after him. The same applies to the Île Laplace in Antarctica.

After Laplace also a genus is Laplacea Kunth from the family of Tea Family named (Theaceae).



  • “Exposition du système du monde”, first edition in two volumes, Paris 1796; last 6th edition revised by Laplace and published posthumously, Paris 1836; Revised new edition of the 6th edition, Fayard, France 1984, reprint of the 1799 edition by Cambridge University Press 2009.
  • “Traité de mécanique céleste”, five volumes, Paris 1798–1825 (reprinted, Brussels 1967).
  • Pierre Simon Laplace: Théorie analytique des probabilités . V. Courcier, Paris 1812, OCLC 1450478 , urn : nbn: de: bvb: 12-bsb10054066-7 .
  • Pierre Simon Laplace: Essai philosophique sur les probabilités . Courcier, Paris 1814, OCLC 1450574 , urn : nbn: de: bvb: 12-bsb10082256-7 (The Essai is a retrospective introduction to the Théorie analytique des probabilités and was edited both separately and in connection with the Théorie analytique).
  • Pierre Simon Laplace: Précis de l'histoire de l'astronomie . V. Courcier, Paris 1821, OCLC 10208507 , urn : nbn: de: bvb: 12-bsb10060999-7 (The outline of the history of astronomy is the final book V of the Exposition du système du monde).
  • Pierre Simon Laplace, Roger Hahn: Correspondance de Pierre Simon Laplace (1749-1827) . Brepols, Turnhout 2013, ISBN 978-2-503-54846-3 .

German translations

  • "Representation of the world system", by Johann Karl Friedrich Hauff, Frankfurt 1797 digitized ; Hauff's translation is based on the French first edition, so Laplace's later revisions were not included in the translation. Heinrich Schmidt published the chapter on cosmogony from the exposition together with Kant's theory of the creation of the world: "The Kant-Laplace theory, ideas on the creation of the world by Immanuel Kant and Pierre Laplace", Leipzig 1925.
  • “Representation of the world system Volume 1, Books 1-3: From the apparent movement of the heavenly bodies / From the true movement of the heavenly bodies / From the laws of movement”, translated by Manfred Jacobi, Franz Kerschbaum, series Ostwalds Klassiker, 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 general gravity / Outline of the history of astronomy”, translated by Manfred Jacobi, Franz Kerschbaum, Ostwalds Klassiker series, Vol. 302, Harri Deutsch, 2008, ISBN 978- 3-8171-3302-4
  • "Mechanics of Heaven", by Johann Carl Burckhardt, Berlin 1800–1802. Burckhardt's translation comprises the first two volumes of the Mécanique céleste.
  • Pierre Simon Laplace: Philosophical attempt on probability: (1814) . Ed .: Richard von Mises. Reprint, 2nd edition. Thun, Frankfurt am Main 1996, ISBN 3-8171-3233-6 .

There are also two work editions

  • “Œuvres”, eight volumes, Paris 1843–1847;
  • “Œuvres complètes” , fourteen volumes, Paris 1878–1912, ed. from the Académie des sciences. That edition is authoritative today.


  • Charles Coulston Gillispie, Robert Fox, Ivor Grattan-Guinness: Pierre-Simon Laplace 1749–1827: a life in exact science . 2nd Edition. Princeton University Press, Princeton 2000, ISBN 0-691-05027-9 (The monograph is the elaboration of the article in the Dictionary of Scientific Biography. The subtitle indicates the biographical character of the book that the authors intend: the book offers a life and a good description of the work).
  • Roger Hahn: Pierre Simon Laplace, 1749-1827: a determined scientist . Harvard University Press, Cambridge, Mass 2005, ISBN 0-674-01892-3 (Hahn's claim is to fill in the biographical gaps of Gillispie and to write about Laplace's role in society, his attitudes towards politics and religion and his family life) .
  • Jörn Henrich : The fixation of the modern ideal of science by Laplace . Akademie-Verlag, Berlin 2010, ISBN 978-3-05-004663-1 .
  • Manfred Jacobi: “The most beautiful monument of the human spirit”. Pierre-Simon Laplace and the representation of the world system . In: Physics in Our Time . tape 41 , no. 2 , 2010, p. 82–86 , doi : 10.1002 / piuz.201001218 .
  • Ursula Klein, Wolfgang Lefèvre: Materials in eighteenth-century science: a historical ontology . MIT Press, Cambridge, Mass 2007, ISBN 978-0-262-11306-9 .

See also

Web links

Commons : Pierre-Simon Laplace  - collection of images, videos and audio files
Wikisource: Pierre-Simon de Laplace  - Sources and full texts
Wikisource: Pierre-Simon Laplace  - Sources and full texts (French)

Individual evidence

  1. ^ Etienne Le Gal / Lucien Klotz: Nos grands savants. Ce que tout Français doit en connaître . Delagrave, Paris 1926. March 23, 1749 is often mentioned as the date of birth, e. B. in: Jean François Eugène Robinet / Adolphe Robert / Julien Le Chaplain: Dictionnaire historique et biographique de la révolution et de l'empire. 1789-1815 . 2 volumes, Paris [1898].
  2. ^ Marie Anne Charlotte de Courty de Romange - Famille de Simon de Solemy de Palmas on GeneaNet
  3. ^ Claudia von Collani: biography of Pierre-Simon (Marquis de) Laplace. (PDF, 102 kB) Stochastikon GmbH, May 10, 2013, archived from the original on January 6, 2014 ; Retrieved January 5, 2014 .
  4. Historical postcard depicting Château Laplace.
  5. Postcard photography of the house by Pierre Simon Laplace, on www.arcueilhistoire.fr/ ( Memento of the original of December 16, 2013 in the Internet Archive ) Info: The archive link has been inserted automatically and has not yet been checked. Please check the original and archive link according to the instructions and then remove this notice. @1@ 2Template: Webachiv / IABot / arcueilhistoire.fr
  6. a b Hervé Faye: Sur l'origine du monde: théories cosmogoniques des anciens et des modern. Gauthier-Villars (Paris), 1884, p. 110 , accessed on January 5, 2014 (French, digitized book, at the Université de Paris Sud, B1-43 table of contents ).
  7. Robert Grant: History of Physical Astronomy, from the earliest ages to the middle of the nineteenth century, etc . HG Bohn, London 1852, OCLC 1131563 , p. 106 ( limited preview in Google Book search).
  8. https://planetarynames.wr.usgs.gov/Feature/6891
  9. Laplace A lpod.wikispaces.com, November 12, 2010
  10. 4628 Pierre-Simon Laplace at the IAU Minor Planet Center (English)
  11. Lotte Burkhardt: Directory of eponymous plant names . Extended Edition. Botanic Garden and Botanical Museum Berlin, Free University Berlin Berlin 2018. [1]
predecessor Office successor
Nicolas Marie Quinette Minister of the Interior of France
November 12, 1799 –25. December 1799
Lucien Bonaparte