1 article for "Laplace, Pierre Simon"

**Laplace, Pierre Simon, Marquis de**[Astro*Index]

(la-plahs')

(1749-1827) French astronomer and mathematician. Born at Beaumont-en- Auge, Calvados; died at Paris, France.

His work with Lavoisier in 1780 showed that the quantity of heat required to decompose a compound is equal to that used when forming the compound, a result which can be said to mark the beginnings of Thermochemistry. Laplace investigated planetary perturbations and the problem of general stability of the solar system. He found, in 1787, that the Moon was accelerating somewhat more than had been accounted for previously, which he attributed to a decrease in the Earth's eccentricity, which was caused by perturbations of the other planets. Extending the work of Lagrange, he showed that certain anomalies in the motions of Jupiter and Saturn could be resolved by considering the mutual gravitational attraction between these massive planets (in addition to the attraction of the Sun upon each). Working cooperatively, but separately, Laplace and Lagrange generalized this result, showing that the total eccentricity of planetary system remained constant (assuming that all bodies revolved about the Sun in the same direction), and that a similar relationship held for the inclinations of the planets. His massive 5-volume work, Celestial Mechanics, summarized work in this field, and was published between 1799 and 1825. His treatise on the Theory of Probability was written sometime between 1812 and 1820. In a popular book on astronomy, Laplace presented a possible scenario in which the Sun and planets condensed out of a rotating gas cloud, similar to that advanced by Kant 40 years earlier.

See also:

♦ Lagrange, Joseph Louis Comte De ♦ Nebulae ♦ Kant, Immanuel

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