Christiaan Huygens

See also: Huygens

Christiaan Huygens (April 14th 1629, $the Hague - July 8th 1695 in the same city) is a Mathématicien, a astronomer and a physicist Dutch. He is the son of Constantijn Huygens.

Huygens is generally credited for its appreciable role in the development with modern calculation, to have in particular developed the techniques of summation and integration necessary to discovered isochronism of the Cycloïde. He was opposed to Leibniz, at the end of his life, insofar as it seemed to him that the infinitesimal calculus was at the bottom only one business of language, the geometry having only to intervene in mathematical working of the phenomena. Calculation would be to some extent only the automation of procedures of demonstrations which an advised geometrician can produce by other means. The development of the infinitesimal calculus at the end of its life will show him all the same (one knows it by its correspondence with Leibniz and Hospital) the power of this tool of which it was right however to denounce the darkness and the mathematical absence of rigor.

The first work of the Huygens young person touches with the elucidation of the rules of the shock. It disputes very quickly, as of 1652, the rules exposed by Descartes in the Principes of philosophy . Taking support on the Cartesian conservation of the Momentum mv , it with the idea algebraically to solve the problem of the shock by comparing the quantities mv ² which are introduced only for the good of calculation, without particular physical significance. Discovering whereas these quantities are preserved before and after the shock, it can write the rules in the general case, which Descartes had not been able to do. It publishes these rules only with delay, in 1669 at the time of a contest launched by the Royal Society, where John Wallis and Christopher Wren gives them also satisfactory rules, though less general.

When Leibniz discovers in Paris, in 1671, the demonstrations of Huygens which use the quantities mv ², he is initially skeptic, then recognizes, in his writings of 1677, which there is a general principle of physics: the principle of conservation of the lifeblood.

In 1655, Huygens discovered Titan, the the moon of Saturn. It also examined the planetary rings Saturn and gave a correct interpretation of the form of those. In 1656, it discovered that these rings consist of Roche S. The same year, it observed the Nébuleuse of Orion. By using its modern Telescope, it could separate nebula in various stars. The part interns most luminous of nebula is currently called the Région of Huygens in its honor. He also discovered several Nébuleuse S and some double stars.

After Blaise Pascal had encouraged it to do it, Huygens wrote the first book on the Theory of probability, which was published in 1657.

Between 1658 and 1659, Huygens works with the theory of the oscillating Pendule. It has indeed the idea to control clocks by means of a pendulum, in order to make the measurement of time more precise. He discovers the formula of the Isochronisme rigorous in December 1659: when the pendulum traverses an arc of Cycloïde, the period of oscillation is constant whatever the amplitude (see also cycloidal Pendule). As opposed to what Galileo had believed to show in the Discours and mathematical demonstrations of 1638, the circular oscillation of the pendulum is not perfectly isochronous if one low exceeds an amplitude of 5 degrees compared to the point.

To apply this discovery to the Clock S, it is necessary to place close to the point of suspension of the pendulum two cycloidal “cheeks” which force the semi-rigid stem to traverse itself cycloid. Obviously the work entitled Horologium that Huygens publishes in 1658 does not bear yet the fruits of this theoretical discovery and is satisfied to describe a model innovating by its regulation (and its system of exhaust) but to which it still misses a theoretical control which will be published only in the Horologium Oscillatorium of 1673.

Huygens was elected “ fellow ” of the Royal Society in 1663. In 1666, Huygens becomes an eminent member of the royal Académie of sciences founded by Colbert with Paris.

Taking part in the realization of the Observatory of Paris, completed in 1672, it will still carry out other astronomical observations there.

Huygens is also known for its arguments according to which the Lumière is made up of Onde S (see: Duality wave-particle).

In answer in the articles of Isaac Newton on the Light, in 1672, it launches out in the study of the nature of the Lumière, following scientists such as Bartholin. He discovers in 1677, thanks to the properties of the crystals and of their geometrical cut (and in particular thanks to the Iceland spar), that the laws of reflection and Réfraction of Snell-Descartes are preserved if one supposes a light propagation in the form of waves. Moreover, the double refraction of the Iceland spar can be explained, which is not the case with a corpuscular theory.

The undulatory Theory, in a form still very little developed and quickly eclipsed by Newtonian successes, was born then under the feather of authors such as the P. Pardies. Augustin Fresnel will find the direction of them, later, in all independence since it does not seem to have known, not more than Young, work of Huygens.

Huygens turned over to $the Hague in 1681 after a serious disease. The death of its guard Colbert in 1683 does not enable him any more to escape the revocation of the Édit from Nantes to the currents from Counter-Reformation which agitate France. He which lived Paris at the time when Louis XIV had declared the war with the United Provinces, must be solved to remain in its residence of Hofwijck and on the Full one with $the Hague for the last years of its scientific career. It is at that time that it writes several manuscripts relating to the need for seizing in a synthetic way its work.

It is also led to meditate on the relations between science and the belief in general. It is at this time that he wonders about the manner of consolidating the assumption copernician. In its book Cosmotheoros, sive of terris coelestibus, earumque ornatu, conjecturae ($the Hague, 1698) it illustrates in two parts the consequences of the thesis copernician. It is located in that in the tradition opened by Pierre Borel, Cyrano of Bergerac, Galileo or Gassendi. On the one hand, it is devoted to conjectures relating to the possibility of other forms of life in a universe where each sun is another world. This reflection leads it to justify the existence of planéticoles under a consequence of the divine grace which must necessarily extend to the unit from the universe and not to be limited to our Ground.

Creationnist, Huygens challenges any upgrading capability or of transformation of the species and it can clearly conceive intelligent life only in one form anthropoïde. In addition, Huygens examines what could be “appearances” such as they would be perceived by an observer located on another center of reference that ours. It is helped then of the Principe of relativity to rebuild these appearances geometrically.

It was the liberal climate with the Netherlands in this time which not only allowed but encouraged such a speculation. One will recall that philosopher Italy N Giordano Bruno, which also thought that many of other worlds were inhabited, was burned on one to rough-hew in 1600 for that.

He dies the July 8th 1695.

The module belonging to the probe Cassini and which landed on Titan was baptized name of Huygens. The Astéroïde (2801) Huygens was also named in its honor.

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