Laplace Articulates His Nebular Hypothesis Summary

  • Last updated on November 10, 2022

Laplace published The System of the World, in which he put forward a theory of the origins of the solar system. He demonstrated mathematically that Newton’s laws of motion and gravity could result in a simple cloud of dust transforming over time into the Sun and planets.

Summary of Event

Pierre-Simon Laplace revolutionized astronomy in 1796, when he published his Exposition du système du monde (The System of the World, 1809), in which he first promulgated his now famous nebular hypothesis on the origin of the solar system. According to Laplace, the solar system derived from a cloud of gas and dust, a gaseous nebula he designated the nébuleuse primitive. In this hot and rotating cloud, the condensation of the material, caused by gravitational attraction, formed the planets. This condensation, according to Laplace, began at the outskirts of the cloud, forming the planets most distant from the Sun first and progressing inward. [kw]Laplace Articulates His Nebular Hypothesis (1796) [kw]Hypothesis, Laplace Articulates His Nebular (1796) [kw]Nebular Hypothesis, Laplace Articulates His (1796) [kw]Articulates His Nebular Hypothesis, Laplace (1796) System of the World, The (Laplace) Solar system Nebular hypothesis [g]France;1796: Laplace Articulates His Nebular Hypothesis[3240] [c]Astronomy;1796: Laplace Articulates His Nebular Hypothesis[3240] [c]Mathematics;1796: Laplace Articulates His Nebular Hypothesis[3240] [c]Science and technology;1796: Laplace Articulates His Nebular Hypothesis[3240] Laplace, Pierre-Simon Alembert, Jean le Rond d’ Berthollet, Claude Louis Napoleon I Napoleon I;Pierre-Simon Laplace[Laplace]

Laplace was born on March 23, 1749, in Beaumont-en-Auge, Normandy. The second of the three sons in a family of five children, Laplace enjoyed a comfortable childhood. His father was a wealthy farmer who augmented his income by running a relay station on a busy stagecoach line, where he sold fermented cider to weary travelers. His mother, Marie-Anne Sochon, came from a comfortably wealthy agricultural family as well.

The Laplace family’s economic security provided Pierre-Simon with educational opportunities that allowed him to develop his considerable intellect. He was sent to a Benedictine priory school for his primary education, and at the age of seventeen, he advanced to the University of Caen, where he discovered his passion and aptitude for mathematics. After two years at the university, he spent the next two years teaching mathematics at his former priory school while he saved enough money to finance a trip to Paris. In the city, he met the famous mathematician Jean le Rond d’Alembert. D’Alembert was immediately interested in Laplace and, in 1770, recommended him as a mathematics teacher at the École Royale Militaire in Paris.

Turning his attention and mathematical skills to astronomy, Laplace came to the attention of the scientific community in 1773, when he produced a groundbreaking essay titled “Sur le principe de la gravitation universelle, et sur les inégalites séculaires des planètes qui en dépendent” [p]"Sur le principe de la gravitation universelle, et sur les inégalites séculaires des planètes qui en dépendent" (Laplace)[Sur le principe de la gravitation universelle, et sur les inegalites seculaires des planetes qui en dependent] (on the principle of universal gravitation, and on the age-old inequalities of the planets that depend upon it). In this paper, he used his mathematical skills to solve a problem in celestial mechanics Celestial mechanics that had puzzled many scholars, including the famous Leonhard Euler and Joseph-Louis Lagrange: There were apparent variations in the speeds at which the planets Planetary orbits revolved around the Sun that seemed to have no reasonable explanation and that seemed to indicate a worrisome instability in the solar system. Indeed, Sir Isaac Newton himself had responded to this instability by saying that the solar system required intermittent divine intervention to keep it going.

Laplace demonstrated that this planetary instability was only apparent; in fact, the variation in the speed of the planets was a periodic phenomenon that could be predicted. Saturn and Jupiter speed up and slow down because of the gravitational effects they have on each other, with a periodicity of 919 years. Laplace thus demonstrated that Newton’s Newton, Sir Isaac Newton, Sir Isaac;theory of motion[motion] laws [p]Motion;and matter[matter] Matter;and motion[motion] Gravity alone were sufficient to explain the mechanics of the solar system, and divine intervention was not necessary. The tables that Laplace created to track and predict the effect that the planets have on one another’s orbits remained in use through the end of the nineteenth century. This work was the basis for his admission as an adjunct in mechanics to the French Academy of Sciences Academy of Sciences, France (Académie des Sciences), where he would rise to become president in 1812.

Illustration of a spiral nebula cyclone.

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In 1785, Laplace was an examiner at the Royal Artillery Corps (mathematical skill was essential to effective artillery fire) when sixteen-year-old Napoleon Bonaparte underwent examination to achieve the rank of second lieutenant. Many years later, Bonaparte was instrumental in advancing his examiner’s career, making him a count and naming him a minister in the government.

The transformational zeal of the French Revolution extended beyond politics and into science. Laplace’s scientific reputation placed him in a intellectual, social, and political position in which he was able to help effect profound changes. In 1790, the French National Assembly wished to replace the more than seven hundred different units of measure employed in the country. Laplace was instrumental in developing the metric system, Metric system giving elegant coherence to what had been a chaotic situation. In 1795, Laplace was a cofounder and first director of the Bureau of Longitudes. He also served as the director of the Paris Observatory.

One year later, in 1796, he published Exposition du système du monde (The System of the World), the work that revolutionized astronomy. It was a huge accomplishment, a series of five books in two volumes devoted to the analysis of the apparent motions of celestial bodies, the movement of the sea, the actual movements of celestial bodies, and the formation of the solar system. Extremely well written and targeted at a semipopular audience, the work not only disseminated Laplace’s theories and analyses but also helped bring Newtonian astrophysics to a wider audience.

Laplace noticed in The System of the World that the planets known at the time (only the seven innermost planets had been discovered) had elliptical trajectories and were almost all in the same plane. Also noting the relatively slow rotation of the Sun itself, Laplace proposed that the solar system had been formed out of a rotating cloud of dust and gas, the nébuleuse primitive. Nébuleuse primitive (nebular cloud) Very hot, this nebular cloud flattened as its rotation increased in speed over time, ejecting small amounts of its particles that would become the planets and their moons. The condensing center of the cloud became the Sun.

In 1806, Napoleon named Laplace a comte d’empire and gave him the position of minister of the interior in his government. Much more a scientist than an administrator, Laplace kept his ministerial position for only six weeks before gracefully withdrawing. In an endeavor more to his liking, in 1807, Laplace, along with the well-known chemist Claude Louis Berthollet, organized a group of famous scientists and young researchers called Société d’Arcueil (Society of Arcueil). Société d’Arcueil (France)[Societe dArcueil] Housed in a property neighboring that of Berthollet and provided with laboratory facilities built for their needs, the group was designed to encourage promising young scientists by enabling them to continue their research under the supervision and mentoring of established and reputable scientists.

Among the significant scientists mentored by the society were physicists Joseph Louis Gay-Lussac and Jean-Baptiste Biot and naturalist and explorer Alexander von Humboldt. Laplace was elected to the French Academy French Academy in 1816, and, in 1817, Louis XVIII named him Marquis de Laplace. During his very long career, Laplace distinguished himself because of his genius, method, analysis, and extraordinary mathematical knowledge. When he died in 1827, at seventy-eight years of age, not only had he revolutionized astronomy, but he had made profound transformations in the field of probability, weights and measures, and mathematics.

Significance

Pierre-Simon Laplace’s nebular hypothesis is still broadly accepted today as the most probable origin of the solar system. When combined with his demonstration that the solar system is stable and its motion is fully self-perpetuating without divine intervention, Divine intervention and astronomy Laplace’s work represents the first rigorous, mathematically precise, and fully secular Secularism;and astronomy[astronomy] description of both the creation and the functioning of the solar system. Laplace perfected the Newtonian theory of mechanics and gravitation and applied it in ways of which Newton himself was incapable. The System of the World was the springboard for the apotheosis of his work, Traité de mécanique céleste (1798-1827; partial translation as A Treatise upon Analytical Mechanics, Treatise upon Analytical Mechanics, A (Laplace) 1814; full translation as Mécanique Céleste, 1829-1839), a five-volume set on which he would labor for the rest of his life.

In a eulogy presented at the French Academy on November 13, 1827, Laplace’s successor, Pierre-Paul Royer-Collard, said that

Laplace was born to perfect everything, to deepen everything, to push back the limits, and to solve all of the things people believe unsolvable. He would have completed the study of astronomy if this science could be completed.

Though the hyperbole of his eulogy was probably extravagant, Laplace did demonstrate the power of combining scientific and mathematical skills in the attempt to understand the workings of the physical universe. His scientific creativity, extraordinary mathematical ability, curiosity, and discipline not only unlocked the secrets of the solar system’s origins but also provided a model of synthesis of disciplines for future scientists to follow.

Further Reading
  • citation-type="booksimple"

    xlink:type="simple">Bell, E. T. “From Peasant to Snob: Laplace.” In Men of Mathematics: The Lives and Achievements of the Great Mathematicians from Zeno to Poincaré. New York: Simon and Schuster, 1986. Bell provides a brief biography of Laplace from his humble origins in the country side of Normandy to the high status he achieved in the sciences and in politics.
  • citation-type="booksimple"

    xlink:type="simple">Crosland, Maurice. Society of Arcueil: A View of French Science at the Time of Napoleon. Boston: Harvard University Press, 1967. Details the work of Laplace and Berthollet, founders of the Society of Arcueil, in encouraging the development of young scientists.
  • citation-type="booksimple"

    xlink:type="simple">Gillipsie, Charles Coulston, Robert Fox, and Ivor Grattan-Guinness. Pierre-Simon Laplace, 1749-1827: A Life in Exact Science. Princeton, N.J.: Princeton University Press, 2000. Describes the life and achievements of Laplace.
  • citation-type="booksimple"

    xlink:type="simple">Hershel, Sir John Frederic William, and Pierre-Simon, Marquis de Laplace. Essays in Astronomy. Honolulu, Hawaii: University Press of the Pacific, 2002. The editor has collected and translated into English many of Laplace’s original articles in this volume.

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Related Articles in <i>Great Lives from History: The Eighteenth Century</i>

Jean le Rond d’Alembert; Jean-Sylvain Bailly; Leonhard Euler; Joseph-Louis Lagrange. System of the World, The (Laplace) Solar system Nebular hypothesis

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