Georges-Louis Le Sage

Encyclopedia

**Georges-Louis Le Sage**was a physicist

Physicist

A physicist is a scientist who studies or practices physics. Physicists study a wide range of physical phenomena in many branches of physics spanning all length scales: from sub-atomic particles of which all ordinary matter is made to the behavior of the material Universe as a whole...

and is most known for his theory of gravitation

Le Sage's theory of gravitation

Le Sage's theory of gravitation is a kinetic theory of gravity originally proposed by Nicolas Fatio de Duillier in 1690 and later by Georges-Louis Le Sage in 1748. The theory proposed a mechanical explanation for Newton's gravitational force in terms of streams of tiny unseen particles impacting...

, for his invention of an electric telegraph and his anticipation of the kinetic theory

Kinetic theory

The kinetic theory of gases describes a gas as a large number of small particles , all of which are in constant, random motion. The rapidly moving particles constantly collide with each other and with the walls of the container...

of gases.

## Life and education

Le Sage was born in GenevaGeneva

Geneva In the national languages of Switzerland the city is known as Genf , Ginevra and Genevra is the second-most-populous city in Switzerland and is the most populous city of Romandie, the French-speaking part of Switzerland...

, his father was Georges-Louis Le Sage from Conques

Conques

Conques is a commune in the Aveyron department in southern France.-Geography:The village is located at the confluence of the Dourdou and Ouche rivers. It is built on a hillside and has classic narrow Medieval streets. As a result, large vehicles cannot enter the historic town centre but must...

in Burgundy and his mother Anne Marie Gamp, a descendant of Théodore Agrippa d'Aubigné. His father, who was the author of many papers on various subjects, occupied his son of his own studies early, including the works of the Roman poet Lucretius

Lucretius

Titus Lucretius Carus was a Roman poet and philosopher. His only known work is an epic philosophical poem laying out the beliefs of Epicureanism, De rerum natura, translated into English as On the Nature of Things or "On the Nature of the Universe".Virtually no details have come down concerning...

at the age of 13. According to Prévost and after some notices of Le Sage, the education by his parents in his early years was very strict, and Le Sage reacted to this by isolating himself and with meditation on various subjects. Contrary to his father, who allegedly only accepted facts and had little interest in generalization, Le Sage was primarily interested in general and abstract principles. This was forced by his weak memory and his tendency to meditation.

Le Sage took the first regular education at the college of Geneva, were was friendly connected with Jean-André Deluc

Jean-André Deluc

Jean-André Deluc or de Luc was a Swiss geologist and meteorologist.-Life:He was born at Geneva, descended from a family which had emigrated from Lucca and settled at Geneva in the 15th century...

. Besides philosophy, he studied mathematics

Mathematics

Mathematics is the study of quantity, space, structure, and change. Mathematicians seek out patterns and formulate new conjectures. Mathematicians resolve the truth or falsity of conjectures by mathematical proofs, which are arguments sufficient to convince other mathematicians of their validity...

under Gabriel Cramer

Gabriel Cramer

Gabriel Cramer was a Swiss mathematician, born in Geneva. He showed promise in mathematics from an early age. At 18 he received his doctorate and at 20 he was co-chair of mathematics.In 1728 he proposed a solution to the St...

, and physics under Calendrini. Later he decided to study medicine

Medicine

Medicine is the science and art of healing. It encompasses a variety of health care practices evolved to maintain and restore health by the prevention and treatment of illness....

in Basel

Basel

Basel or Basle In the national languages of Switzerland the city is also known as Bâle , Basilea and Basilea is Switzerland's third most populous city with about 166,000 inhabitants. Located where the Swiss, French and German borders meet, Basel also has suburbs in France and Germany...

, where he also gave private lessons in mathematics. Here, Le Sage also met Daniel Bernoulli, whose work on the kinetic nature of gases was very influential to him. Then Le Sage left Basel and continued to study medicine in Paris

Paris

Paris is the capital and largest city in France, situated on the river Seine, in northern France, at the heart of the Île-de-France region...

. After he came back to Geneva, Le Sage tried to work as a physician, but it was denied because his father was a native from France. There, he was friendly connected with Charles Bonnet

Charles Bonnet

Charles Bonnet , Swiss naturalist and philosophical writer, was born at Geneva, of a French family driven into Switzerland by the religious persecution in the 16th century.-Life and work:Bonnet's life was uneventful...

.

Against the will of his father Le Sage devoted his life to mathematics

Mathematics

Mathematics is the study of quantity, space, structure, and change. Mathematicians seek out patterns and formulate new conjectures. Mathematicians resolve the truth or falsity of conjectures by mathematical proofs, which are arguments sufficient to convince other mathematicians of their validity...

and, in particular, a search for the mechanisms of gravity. He tried to become a professor for mathematics in Geneva, but he couldn't get the position.

Although Le Sage published not many papers in his life, he had an extensive letter exchange to people like Jean le Rond d'Alembert

Jean le Rond d'Alembert

Jean-Baptiste le Rond d'Alembert was a French mathematician, mechanician, physicist, philosopher, and music theorist. He was also co-editor with Denis Diderot of the Encyclopédie...

, Leonhard Euler

Leonhard Euler

Leonhard Euler was a pioneering Swiss mathematician and physicist. He made important discoveries in fields as diverse as infinitesimal calculus and graph theory. He also introduced much of the modern mathematical terminology and notation, particularly for mathematical analysis, such as the notion...

, Paolo Frisi

Paolo Frisi

Paolo Frisi was an Italian mathematician and astronomer.-Biography:Born in Melegnano, Frisi was educated at the local Barnabite monastery and afterwards in that of Padua...

, Roger Joseph Boscovich

Roger Joseph Boscovich

Ruđer Josip Bošković was a theologian, physicist, astronomer, mathematician, philosopher, diplomat, poet, Jesuit, and a polymath from the city of Dubrovnik in the Republic of Ragusa , who studied and lived in Italy and France where he also published many of his works.He is famous for...

, Johann Heinrich Lambert

Johann Heinrich Lambert

Johann Heinrich Lambert was a Swiss mathematician, physicist, philosopher and astronomer.Asteroid 187 Lamberta was named in his honour.-Biography:...

, Pierre Simon Laplace, Daniel Bernoulli

Daniel Bernoulli

Daniel Bernoulli was a Dutch-Swiss mathematician and was one of the many prominent mathematicians in the Bernoulli family. He is particularly remembered for his applications of mathematics to mechanics, especially fluid mechanics, and for his pioneering work in probability and statistics...

, Firmin Abauzit, Lord Stanhope

Charles Stanhope, 3rd Earl Stanhope

Charles Stanhope, 3rd Earl Stanhope aka Charles Mahon, 3rd Earl Stanhope FRS was a British statesman and scientist. He was the father of the great traveller and Arabist Lady Hester Stanhope and brother-in-law of William Pitt the Younger. He is sometimes confused with an exact contemporary of his,...

etc..

He gave private lessons in mathematics, and his pupils, including La Rochefoucauld

La Rochefoucauld

La Rochefoucauld can refer to:People:* Antoine de La Rochefoucauld* Count Antoine de La Rochefoucauld , 19th century Rosicrucian* François de La Rochefoucauld , French author...

, Simon Lhuilier, Pierre Prévost

Pierre Prévost

Pierre Prévost was a Swiss philosopher and physicist. In he showed that all bodies radiate heat, no matter how hot or cold they are.-Life:...

, were deeply impressed by his personality. He was a correspondent of the Paris Academy of Science and also became a foreign member of the Royal Society

Royal Society

The Royal Society of London for Improving Natural Knowledge, known simply as the Royal Society, is a learned society for science, and is possibly the oldest such society in existence. Founded in November 1660, it was granted a Royal Charter by King Charles II as the "Royal Society of London"...

. Le Sage died at the age of 79 in Geneva.

## Character and health

Le Sage described his manner of thinking and working by saying:I have been born with four dispositions well adapted for making progress in science, but with two great defects in the faculties necessary for that purpose. 1. An ardent desire to know the truth; 2. Great activity of mind; 3. An uncommon (justesse) soundness of understanding; 4. A strong desire for precision and distinctness of ideas; 5. An excessive weakness of memory; 6. A great incapacity of continued attention.

Le Sage also suffered from insomnia, and as a result of this he often was unable to work for days. Additionally, in 1762 he had an accident which left him nearly blind.

To compensate the weakness of his memory, he wrote his thoughts on playing cards - over 35000 cards are still lying in the library of Geneva. As a consequence of his mental disposition, many of his papers remained unfinished and unpublished. For example: his main work on Gravitation; a history of theories of gravitation; a treatise on final causes; a biographical note on Nicolas Fatio de Duillier

Nicolas Fatio de Duillier

Nicolas Fatio de Duillier was a Swiss mathematician known for his work on the zodiacal light problem, for his very close relationship with Isaac Newton, for his role in the Newton v. Leibniz calculus controversy, and for originating the "push" or "shadow" theory of gravitation...

. However, some of them were posthumously published by his pupil Pierre Prévost

Pierre Prévost

Pierre Prévost was a Swiss philosopher and physicist. In he showed that all bodies radiate heat, no matter how hot or cold they are.-Life:...

.

## Telegraph

In 1774 he realised an early electric telegraph. The telegraph had a separate wire for each of the 26 letters of the alphabetAlphabet

An alphabet is a standard set of letters—basic written symbols or graphemes—each of which represents a phoneme in a spoken language, either as it exists now or as it was in the past. There are other systems, such as logographies, in which each character represents a word, morpheme, or semantic...

and its range was only between two rooms of his home.

## Kinetic Theory

Le Sage also tried to explain the nature of gases. This attempt was appreciated by Rudolf ClausiusRudolf Clausius

Rudolf Julius Emanuel Clausius , was a German physicist and mathematician and is considered one of the central founders of the science of thermodynamics. By his restatement of Sadi Carnot's principle known as the Carnot cycle, he put the theory of heat on a truer and sounder basis...

and James Clerk Maxwell

James Clerk Maxwell

James Clerk Maxwell of Glenlair was a Scottish physicist and mathematician. His most prominent achievement was formulating classical electromagnetic theory. This united all previously unrelated observations, experiments and equations of electricity, magnetism and optics into a consistent theory...

. Maxwell wrote: His theory of impact is faulty, but his explanation of the expansive force of gases [i.e., pressure] is essentially the same as in the dynamical theory, as it now stands.

Le Sage also clearly pointed out, that he was not the first one who described such a mechanism, and referred to Lucretius

Lucretius

Titus Lucretius Carus was a Roman poet and philosopher. His only known work is an epic philosophical poem laying out the beliefs of Epicureanism, De rerum natura, translated into English as On the Nature of Things or "On the Nature of the Universe".Virtually no details have come down concerning...

, Gassendi

Pierre Gassendi

Pierre Gassendi was a French philosopher, priest, scientist, astronomer, and mathematician. With a church position in south-east France, he also spent much time in Paris, where he was a leader of a group of free-thinking intellectuals. He was also an active observational scientist, publishing the...

, Hermann

Jakob Hermann

Jakob Hermann was a mathematician who worked on problems in classical mechanics. He is the author of Phoronomia, an early treatise on Mechanics. In 1729, he proclaimed that it was as easy to graph a locus on the polar coordinate system as it was to graph it on the Cartesian coordinate system...

and Bernoulli

Daniel Bernoulli

Daniel Bernoulli was a Dutch-Swiss mathematician and was one of the many prominent mathematicians in the Bernoulli family. He is particularly remembered for his applications of mathematics to mechanics, especially fluid mechanics, and for his pioneering work in probability and statistics...

.

### History

In his early youth Le Sage was strongly influenced by the writings of the Roman poet LucretiusLucretius

Titus Lucretius Carus was a Roman poet and philosopher. His only known work is an epic philosophical poem laying out the beliefs of Epicureanism, De rerum natura, translated into English as On the Nature of Things or "On the Nature of the Universe".Virtually no details have come down concerning...

and incorporated some of Lucretius’ ideas into a mechanical explanation of gravitation

Mechanical explanations of gravitation

Mechanical explanations of gravitation are attempts to explain the action of gravity by aid of basic mechanical processes, such as pressure forces caused by pushes, and without the use of any action at a distance. These theories were developed from the 16th until the 19th century in connection...

, which he subsequently worked on and defended throughout his life. Le Sage wrote in one of his cards, that he developed the basic features of the theory, which was later called Le Sage's theory of gravitation

Le Sage's theory of gravitation

Le Sage's theory of gravitation is a kinetic theory of gravity originally proposed by Nicolas Fatio de Duillier in 1690 and later by Georges-Louis Le Sage in 1748. The theory proposed a mechanical explanation for Newton's gravitational force in terms of streams of tiny unseen particles impacting...

, already in 1743. Then on January 15, 1747 Le Sage wrote to his father:

Eureka, Eureka. Never have I had so much satisfaction as at this moment, when I have just explained rigorously, by the simple law of rectilinear motion, those of universal gravitation, which decreases in the same proportion as the squares of the distance increase.

The first exposition of his theory, "Essai sur l'origine des forces mortes", was created by him in 1748, but was never published. In 1756 one of Le Sage's expositions of the theory was published, and in 1758 he sent a more detailed exposition of the theory to another competition of the Academy of Sciences. In this paper, entitled "Essai de Chymie Méchanique", he tried to explain both the nature of gravitation and chemical affinities. He shared the prize with one other entrant, but his theory of cohesion never gained acceptance, and only the gravitational portion of the theory was found to be of interest by a few of his contemporaries, including Euler

Leonhard Euler

Leonhard Euler was a pioneering Swiss mathematician and physicist. He made important discoveries in fields as diverse as infinitesimal calculus and graph theory. He also introduced much of the modern mathematical terminology and notation, particularly for mathematical analysis, such as the notion...

. The exposition of the theory which became accessible to a broader public was "Lucrèce Newtonien" ("The Newtonian Lucretius"), in which the correspondence with Lucretius’ concepts was fully developed. Another exposition of the theory was published from Le Sage's notes posthumously by Prévost

Pierre Prévost

Pierre Prévost was a Swiss philosopher and physicist. In he showed that all bodies radiate heat, no matter how hot or cold they are.-Life:...

in 1818, and was called "Physique Mécanique de George Louis Le Sage", but it doesn't contain anything which wasn't published in the earlier papers.

### Le Sage's predecessors

Le Sage was not the first to propose what is now called “Le Sage’s theory of gravity”. Those who had described the theory previously include Fatio, Cramer, and Redeker. The extent to which Le Sage was influenced by these predecessors is a matter of controversy.#### Fatio

The theory now called “Le Sage’s theory of gravity” was originally proposed in the 1690s by Nicolas Fatio de Duillier, a friend of Isaac Newton and Christian Huygens. Fatio was a well-known Swiss personage, and the kinetic theory of gravitation was his most notable scientific contribution, to which he devoted much of his life. Le Sage said that he heard of Fatio for the first time through his father, because his father had heard the prophecies of the cevénots (camisards), and told him that Fatio was among those prophets. Le Sage’s father was well acquainted with the scientific fields in which Fatio worked, and he tutored Le Sage in the sciences. Nevertheless, Le Sage later claimed that his father never told him that Fatio had created a theory of gravitation essentially identical to his own. (Le Sage also admitted that he had a pathologically bad memory, so it is unclear if his recollection is accurate.) In any case, Le Sage stated that he knew nothing of Fatio’s theory until he was informed by his teacher Gabriel Cramer in 1749.A few years after Fatio's death (which occurred in 1753), Le Sage began trying to acquire Fatio's papers to – according to his own words – rescue them from oblivion, and also for a treatise he planned to write on the history of theories of gravitation. One of Fatio's papers was sent to Le Sage by Abauzit in 1758, and other papers were acquired by Le Sage in 1766, 1770 and 1785. He also started a biographical note on Fatio, although he didn't complete it, and he tried without success to publish some of Fatio's papers. The Geneva manuscripts were deposited in the library of Geneva by Prévost after Le Sage's death and are still there.

The Bopp edition is a full reprint of the only completely surviving manuscript of Fatio, which was preserved by Daniel Bernoulli Daniel Bernoulli Daniel Bernoulli was a Dutch-Swiss mathematician and was one of the many prominent mathematicians in the Bernoulli family. He is particularly remembered for his applications of mathematics to mechanics, especially fluid mechanics, and for his pioneering work in probability and statistics... and published by Karl Bopp Karl Bopp Karl Bopp was a German historian of mathematics.Bopp studied at the University of Strasbourg and the University of Heidelberg under Moritz Cantor. In 1906 he habilitated with a work about the Conic sections of Gregorius a Sancto Vincenti, and in 1915 he became professor extraordinarius in Heidelberg... in 1929. It contains every part of the Geneva manuscripts (including Problem 1, 2, 3 and 4). The Gagnebin edition from 1949 is based on three (of six) Geneva manuscripts (GM), which were preserved by Le Sage. It includes revisions made by Fatio as late as 1743, forty years after he composed the manuscript on which the Bopp edition was based. However, "Problems 2,3 and 4" contain the mathematically most advanced parts of Fatio's theory, and were not included by Gagnebin in his edition, because he ignored GM 4,5,6. |
|||
---|---|---|---|

Geneva manuscripts |
Corresponding sections in Gagnebin edition |
Date of submissionto Le Sage |
Corresponding pagesin Bopp edition |

GM1 | 34-52 | 29 March 1766 by J.P. Mallet | pp. 38–45 |

GM2 | 1-24 | 17 October 1770 by F. Jallabert | pp. 22–30 |

GM3 | 16-35 | Unknown | pp. 27–38 |

GM4 | Not included | Unknown | pp. 50–56 (Problem 4) |

GM5 | Not included, but the first part is similar to 27-34 (Problem 1) | Unknown | pp. 32–35 (Problem 1), 47-50 (Problem 2 & 3), 53-58 (Problem 4) |

GM6 | Not included, but some parts are similar to 5, 7-10, 12-16, 19-23, 27-36 | 21 May 1758 by Firmin Abauzit | partially pp. 22–39 and pp. 47–49 (Problem 2) |

Le Sage wrote to Lambert in 1768: "Nicolas Fatio de Duillier had created a theory in 1689, which is so similar to mine, that it only differed in the elasticity, which he has given his intensely agitated matter". There he outlined the great similarity of the theories, but incorrectly claimed that Fatio assumed elastic collisions, even though the loss of speed of the gravitational corpuscles was explicitly stressed by Fatio as a crucial element of his theory. Le Sage sent in a letter to Boscovich the beginning of Fatio's Latin poem (modeled on Lucretius) on the subject of his theory of gravitation, and told him that he wanted to publish it, but Boscovich didn't agree, arguing that it would be too hard for most people to understand if it is published in Latin.

Le Sage was worried about the possibility that people might think he had gotten the idea for the gravitation theory from Fatio, because he went to the trouble of making a “certificate”, and having it signed by the mathematician Pfleiderer and the astronomer Mallet (two friends of Le Sage), stating that, except for a copy made by Abauzit in 1758, Le Sage saw no papers of Fatio before 1766, and in these papers there was nothing which wasn't developed by Le Sage in a more detailed way.

In the "Physique Mécanique" published by Prevost after Le Sage’s death, Fatio is mentioned in connection with the net structure of matter, but it goes on to claim that he (Le Sage) had developed the idea of the net structure already in 1763, before he was in possession of Fatio's original papers. However, according to Zehe's description of the Abauzit manuscript from 1758, this paper contains Fatio's description of the net structure of matter. In the same paper, Le Sage repeated the incorrect claim that Fatio assumed "elastic" collisions – and therefore didn’t really provide a valid explanation of gravity. Zehe attempted to account for Le Sage's puzzling claims that Fatio assumed "elastic" collisions by speculating that Le Sage must not have studied Fatio's papers very closely.

In general, Le Sage and Prévost claimed that Le Sage's theory was superior to that of Fatio, but a more recent and detailed analysis of Fatio's paper by Zehe shows that it is Fatio's theory which is more developed.

#### Cramer, Redeker

According to Le Sage, after creating his first essay on gravitation, he was informed in 1748 by Firmin Abauzit about a very similar theory of Gabriel Cramer, who happens to have been Le Sage’s teacher in Geneva. In later years Le Sage responded in two different ways to charges that his ideas on gravitation were only the result of studying Cramer's papers. First, he argued that his first essay was written before he knew of the theories of his predecessors. Second, he argued that even if he knew about Cramer's theory, it makes no difference, because Cramer's theory is too vague and scientifically not valuable.. Le Sage did, however, accuse Cramer of plagiarizing Fatio’s theory. (Fatio himself had made the same accusation.)In 1751 Le Sage also became aware of Redeker 's theory. Le Sage began to write a history of theories of gravitation, in which he intended to describe the theories of Fatio and Redeker, but he never finished it.

#### Summary

Although Le Sage acknowledged that he wasn't the first one to propose such a theory, he always said that he was the first one who ever drew all consequences from the theory, even after coming into possession of Cramer's, Fatio's and Redeker's papers. For example, in his "Lucrece Newtonien" (1782) Le Sage didn't mention any of his predecessors by name. He merely stated that it was "likely" such a simple idea had occurred to others previously, but if so, they had "presented it in a vague and ill-assured fashion". He went on to ask rhetorically why none of these supposed predecessors (of whom he professes to have no definite knowledge) "pushed these consequences to their conclusion and communicated their research". He suggested that the answer was that they had no clear view of the subject, had not firmly grasped the principles of the theory, had allowed themselves to be seduced by specious sophisms, had bowed to the authority of great names, or had "lacked sufficient love of truth or courage of their convictions to abandon easy pleasures and exterior advantages in order to devote themselves to researches at the time difficult and little welcome.".Prévost praised his friend Le Sage for "scrupulously giving credit to his predecessors in all of his writings". However, although he sometimes referred to those predecessors, he often spoke in a derogatory way about them - see his comments in "Lucrece Newtonien", and his appraisal of Cramer as too vague and scientifically not valuable. Lord Kelvin and Aronson repeated Prevost's praise, based only on Prevost's account.

## Endnotes

For the complete references see the biographies and the historical references in Le Sage's theory of gravitationLe Sage's theory of gravitation

Le Sage's theory of gravitation is a kinetic theory of gravity originally proposed by Nicolas Fatio de Duillier in 1690 and later by Georges-Louis Le Sage in 1748. The theory proposed a mechanical explanation for Newton's gravitational force in terms of streams of tiny unseen particles impacting...