Who was Pierre-Simon Laplace and what is he famous for?
Pierre-Simon Laplace (the 23rd of March 1749 - the 5th of March 1827) was a French mathematician, astronomer, and physicist known as the French Newton. He is famous for the five-volume Mécanique céleste, which translated Newton's Principia into the language of calculus; for developing the Bayesian interpretation of probability; for the Laplace transform and Laplace's equation; and for the dynamic theory of tides and the nebular hypothesis of the Solar System's origin.
What did Pierre-Simon Laplace discover about Jupiter and Saturn?
Laplace solved the longstanding problem of the Jupiter-Saturn great inequality. He showed that the apparent shrinking of Jupiter's orbit and expansion of Saturn's was not a sign of instability but a slow oscillation caused by the near-commensurability of the two planets' orbital periods: two periods of Saturn's orbit almost equal five of Jupiter's. The resulting perturbations amount to about 0.8 degrees of arc for Saturn and 0.3 degrees for Jupiter, cycling over a period of nearly 900 years.
What is Laplace's demon?
Laplace's demon is a thought experiment Laplace published in 1814 describing a hypothetical intellect that knows all forces in nature and all positions of every particle in the universe. For such an intellect, nothing would be uncertain and the future, like the past, would be entirely present to it. Laplace himself called it simply "une intelligence" and never used the word demon, which was a later addition by others.
What did Laplace say to Napoleon about God?
The most commonly reported version has Laplace replying to Napoleon's question about the absence of God from his book on astronomy: "Je n'avais pas besoin de cette hypothèse-là" (I had no need of that hypothesis). The astronomer Hervé Faye argued in 1884 that the widely circulated account was distorted, and that Laplace was referring not to God's existence but only to Newton's hypothesis of divine intervention to keep the Solar System stable. Laplace himself reportedly tried before his death to have the story suppressed.
What is the Laplace dynamic theory of tides?
Laplace developed the dynamic theory of tides in 1775, accounting for friction, resonance, and the natural periods of ocean basins. It correctly predicted amphidromic systems in ocean basins and explains why real tidal ranges can reach up to fifteen meters, far beyond the less than half a meter predicted by the earlier equilibrium theory. Satellite data from the CHAMP satellite, matched against TOPEX models, has since confirmed the theory's accuracy.
What was Laplace's five-volume Mécanique céleste?
The Mécanique céleste (Celestial Mechanics) was published in five volumes between 1799 and 1825. It translated Newton's geometric methods into differential calculus, solved problems Newton had left incomplete, and provided a comprehensive mathematical account of the Solar System. The first two volumes covered planetary motions and tidal problems; the third and fourth (published in 1802 and 1805) added applications and astronomical tables; the fifth (1825) was mainly historical with appended new research.