Evangelista Torricelli

Evangelista Torricelli (* October 15, 1608 in Faenza, † October 25, 1647 in Florence ) was an Italian physicist and mathematician. He transferred in 1640 the Galilean law of falling bodies on flowing liquids ( " Torricelli cal outflow Act"), in 1642 in Florence 's successor as court mathematician Galileo Galilei and was instrumental in the development of calculus. Torricelli developed in 1644 the mercury barometer, at the upper end of it an artificial vacuum created ( " torricelische emptiness "). Torricelli's experiment fired the bitterly fought in Europe in the 17th century debate on a horror vacui of new and developed into the philosophy of nature standard problem this time. Plenisten and Vacuinisten argued in the following decades of the properties and the nature of this Torricellian space.

Life

Torricelli came from a poor family, studied from 1624 (probably in his hometown of ) mathematics and philosophy, and later with Benedetto Castelli - temporarily as his secretary - in Rome mathematics, astronomy and mechanics. It seems that his work as secretary (1626-1632) the fee for the lesson represented, which he received at Castelli.

In Rome he met the 1632 published Dialogo and other writings of Galileo Galilei know that impressed and influenced him. From a letter to Galileo, Torricelli, we know that he held the Copernican idea is right; in view of the strained against Galileo process, however, he put back the Astronomy and devoted himself to physical and mathematical problems. From 1632 he worked as a secretary for Giovanni Ciampoli, a friend of Galileo.

In late autumn 1641 - three months before Galileo's death - he went on the recommendation of Castelli Arcetri, near Florence, where he was Galileo's assistant and eventually his successor as court mathematician to the Grand Duke of Tuscany, and as a professor of mathematics at the Florentine Academy. Until his death he lived as court mathematician in the ducal palace in Florence. From 1644 he also worked as a teacher for fixing beings. He was not only a skilful experimenter, but also an excellent lens grinder, which he located in Florence produced a significant additional income. In 1642 he became a member of the Florentine Accademia della Crusca.

At the age of 39 years Torricelli died of an infection (probably typhus ).

Work

Torricelli is one of the most important physicists and mathematicians of the Baroque period, the sciences, he significantly influenced by his contemporaries Galileo Galilei, René Descartes, Bonaventura Cavalieri, Pierre de Fermat and Blaise Pascal.

In 1644 he published his seminal work on the laws in the case and throw ( De motu gravium naturaliter descendentium ). This was the second part of the three -volume work geometrica Opera, where his research on the hydrodynamics were reflected and excited fast lively interest in all of Europe.

Attention has been paid mainly to the later so-called " Torricelli theorem ", which states that when a low-viscosity liquid outflow from a vessel, the outflow rate is proportional to the square root of the height of the liquid. Thus, it does not depend on the density of the liquid; Thus, for example water and mercury at the same filling level flow from the same speed.

In addition to these basic observations on the dynamics of liquids Torricelli has also provided crucial groundwork for calculus. Cavalieri, also a pupil of Castelli had further developed the ideas of Kepler infinitesimal operands. There, he succeeded the derivative of a function with a negative exponent to be determined. With the help of Indivisiblenmethode Torricelli discovered in the study of hyperbolic rotation body, the existence of infinitely extended body with finite volume. Using this method, he found most elegant proofs for geometric problems - such that the volume of a rotating hyperbola is finite ( although its surface is infinite, see Gabriel's horn). Especially in his De motu gravium ... he was able to successfully investigate the parabolic motion of projectiles by means of this procedure.

Torricelli developed a method by which the tangent direction of a curve could be determined as the direction of the instantaneous velocity of a moving point along the curve. This method was later developed by Isaac Barrow and Isaac Newton to Fluxionsmethode.

He improved Galileo's telescope and developed a simple but already powerful microscope.

He was also the first who managed to maintain a vacuum for a long time. His most important discovery concerned the operating principle of the mercury barometer: He put forward the claim that the liquid is not sucked up by the vacuum, but is forced by the weight of the air column up. This assumption was quite controversial. René Descartes wrote, vacuum was to be found at most in Torricelli's head. But you could be in 1647 supported by the experiment emptiness in the void of Blaise Pascal. The vacuum above the mercury in the barometer is often referred to in older literature as Torricelli emptiness. The development of wind as a result of temperature and pressure differences in the atmosphere has stated correctly Torricelli.

The Torr: - obsolete - unit of measure named after Torricelli one is. Also an excellent point triangle, the Fermat - Torricelli point, Torricelli's trumpet and the moon crater Torricelli bear his name.

Priority dispute

1646 Torricelli received a letter from Gilles Personne de Roberval, in which he claimed to have taught the Indivisiblenmethode already ten years earlier, and the example of curves in particular demonstrates the spiral. A priority dispute, which subsequently could no longer be clearly enlighten.

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