- Laplace on probability and statistics!
- The Manly Art of Seduction, How to Meet, Talk to, and Become Intimate with Anyone;
- Exposition du système du monde (French Edition).

He was born to a wealthy family, but first studied at Benedictine College in his hometown. Later he transferred to the University of Caen in Laplace made many achievements in applied mathematics and astronomy, and their effects are still being felt today. Starting in , he applied his mathematical talents to celestial mechanics problems. He made groundbreaking work in the orbital interactions between Saturn and Jupiter, lunar orbital motion, the shape of planetary bodies, tides, and the stability of the solar system.

This memoir was followed by another on planetary inequalities, which was presented in three sections in , , and Laplace shewed by general considerations that the mutual action of two planets could never largely affect the eccentricities and inclinations of their orbits; and that the peculiarities of the Jovian system were due to the near approach to commensurability of the mean motions of Jupiter and Saturn: further developments of these theorems on planetary motion were given in his two memoirs of and It was on these data that Delambre computed his astronomical tables. The year was rendered memorable by Laplace's explanation and analysis of the relation between the lunar acceleration and the secular changes in the eccentricity of the earth's orbit: this investigation completed the proof of the stability of the whole solar system on the assumption that it consists of a collection of rigid bodies moving in a vacuum.

The former was published in , and gives a general explanation of the phenomena, but omits all details. It contains a summary of the history of astronomy: this summary procured for its author the honour of admission to the forty of the French Academy; it is commonly esteemed one of the masterpieces of French literature, though it is not altogether reliable for the later periods of which it treats. The nebular hypothesis was here enunciated.

## Exposition du système du monde

According to this hypothesis the solar system has been evolved from a globular mass of incandescent gas rotating around an axis through its centre of mass. As it cooled this mass contracted and successive rings broke off from its outer edge. These rings in their turn cooled, and finally condensed into the planets, while the sun represents the central core which is still left. On this view we should expect that the more distant planets would be older than those nearer the sun.

The subject is one of great difficulty, and though it seems certain that the solar system has a common origin, there are various features which appear almost inexplicable on the nebular hypothesis as enunciated by Laplace. Another theory which avoids many of the difficulties raised by Laplace's hypothesis has recently found favour.

## Pierre Simon Laplace (1749 - 1827)

According to this, the origin of the solar system is to be found in the gradual aggregation of meteorites which swarm through our system, and perhaps through space. These meteorites which are normally cold may, by repeated collisions, be heated, melted, or even vaporized, and the resulting mass would, by the effect of gravity, be condensed into planet-like bodies - the larger aggregations so formed becoming the chief bodies of the solar system.

To account for these collisions and condensations it is supposed that a vast number of meteorites were at some distant epoch situated in a spiral nebula, and that condensations and collisions took place at certain knots or intersections of orbits.

As the resulting planetary masses cooled, moons or rings would be formed either by collisions of outlying parts or in the manner suggested in Laplace's hypothesis. This theory seems to be primarily due to Sir Norman Lockyer. It does not conflict with any of the known facts of cosmical science, but as yet our knowledge of the facts is so limited that it would be madness to dogmatize on the subject.

Recent investigations have shown that our moon broke off from the earth while the latter was in a plastic condition owing to tidal friction.

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Hence its origin is neither nebular nor meteoric. Probably the best modern opinion inclines to the view that nebular condensation, meteoric condensation, tidal friction, and possibly other causes as yet unsuggested, have all played their part in the evolution of the system. The idea of the nebular hypothesis had been outlined by Kant in , and he had also suggested meteoric aggregations and tidal friction as causes affecting the formation of the solar system: it is probable that Laplace was not aware of this. It would be an interesting fact if this could be deduced from the nebular, meteoric, or any other hypotheses, but so far as I am aware only one writer has made any serious attempt to do so, and his conclusion seems to be that the law is not sufficiently exact to be more than a convenient means of remembering the general result.

An analysis of the contents is given in the English Cyclopaedia. The first two volumes, published in , contain methods for calculating the motions of the planets, determining their figures, and resolving tidal problems.

## Exposition Du Systeme Du Monde () : marquis de Pierre Simon Laplace :

The third and fourth volumes, published in and , contain applications of these methods, and several astronomical tables. The original itself is in the public domain for the following reason: Public domain Public domain false false This work is in the public domain in its country of origin and other countries and areas where the copyright term is the author's life plus years or fewer. This file has been identified as being free of known restrictions under copyright law, including all related and neighboring rights.

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