Jean le Rond d'Alembert
Encyclopedia
Jean-Baptiste le Rond d'Alembert (ʒɑ̃ batist lə ʁɔ̃ dalɑ̃bɛːʁ) (16 November 1717 – 29 October 1783) was a French mathematician
Mathematician
A mathematician is a person whose primary area of study is the field of mathematics. Mathematicians are concerned with quantity, structure, space, and change....

, mechanician
Mechanics
Mechanics is the branch of physics concerned with the behavior of physical bodies when subjected to forces or displacements, and the subsequent effects of the bodies on their environment....

, 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...

, philosopher, and music theorist. He was also co-editor with Denis Diderot
Denis Diderot
Denis Diderot was a French philosopher, art critic, and writer. He was a prominent person during the Enlightenment and is best known for serving as co-founder and chief editor of and contributor to the Encyclopédie....

 of the Encyclopédie
Encyclopédie
Encyclopédie, ou dictionnaire raisonné des sciences, des arts et des métiers was a general encyclopedia published in France between 1751 and 1772, with later supplements, revised editions, and translations. It was edited by Denis Diderot and Jean le Rond d'Alembert...

. D'Alembert's formula for obtaining solutions to the wave equation
Wave equation
The wave equation is an important second-order linear partial differential equation for the description of waves – as they occur in physics – such as sound waves, light waves and water waves. It arises in fields like acoustics, electromagnetics, and fluid dynamics...

 is named after him.

Childhood

Born 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...

, d'Alembert was the illegitimate child of the writer Claudine Guérin de Tencin
Claudine Guérin de Tencin
Claudine Alexandrine Guérin de Tencin was a French salonist and author. She was the mother of Jean le Rond d'Alembert, philosophe and contributor to the Encyclopédie.- Early life :...

 and the chevalier Louis-Camus Destouches
Louis-Camus Destouches
Louis-Camus Destouches was a French artillery officer.He was a chevalier of the ordre de Saint-Lazare from 1690, and became a chevalier of the ordre de Saint-Louis in 1720, then commandeur in 1725...

, an artillery
Artillery
Originally applied to any group of infantry primarily armed with projectile weapons, artillery has over time become limited in meaning to refer only to those engines of war that operate by projection of munitions far beyond the range of effect of personal weapons...

 officer. Destouches was abroad at the time of d'Alembert's birth, and a couple of days after birth his mother left him on the steps of the Saint-Jean-le-Rond de Paris church. According to custom, he was named after the patron saint
Patron saint
A patron saint is a saint who is regarded as the intercessor and advocate in heaven of a nation, place, craft, activity, class, clan, family, or person...

 of the church. D'Alembert was placed in an orphanage
Orphanage
An orphanage is a residential institution devoted to the care of orphans – children whose parents are deceased or otherwise unable or unwilling to care for them...

 for found children, but was soon adopted by the wife of a glazier
Glazier
A Glazier is a construction professional who selects, cuts, installs, replaces, and removes residential, commercial, and artistic glass. Glaziers also install aluminum storefront frames and entrances, glass handrails and balustrades, shower enclosures, curtain wall framing and glass and mirror...

. Destouches secretly paid for the education of Jean le Rond, but did not want his paternity
Paternity (law)
In law, paternity is the legal acknowledgment of the parental relationship between a man and a child usually based on several factors.At common law, a child born to the wife during a marriage is the husband's child under the "presumption of legitimacy", and the husband is assigned complete rights,...

 officially recognized.

Studies and adult life

D'Alembert first attended a private school. The chevalier Destouches left d'Alembert an annuity of 1200 livre
Livré
Livré-la-Touche is a commune in the Mayenne department in north-western France. Prior to October 6, 2008, it was known as Livré....

s on his death in 1726. Under the influence of the Destouches family, at the age of twelve d'Alembert entered the Jansenist
Jansenism
Jansenism was a Christian theological movement, primarily in France, that emphasized original sin, human depravity, the necessity of divine grace, and predestination. The movement originated from the posthumously published work of the Dutch theologian Cornelius Otto Jansen, who died in 1638...

 Collège des Quatre-Nations
Collège des Quatre-Nations
The Collège des Quatre-Nations , also known as the Collège Mazarin after its founder, was one of the colleges of the historic University of Paris. It was founded through a bequest by the Cardinal Mazarin...

 (the institution was also known under the name "Collège Mazarin"). Here he studied philosophy
Philosophy
Philosophy is the study of general and fundamental problems, such as those connected with existence, knowledge, values, reason, mind, and language. Philosophy is distinguished from other ways of addressing such problems by its critical, generally systematic approach and its reliance on rational...

, law
Law
Law is a system of rules and guidelines which are enforced through social institutions to govern behavior, wherever possible. It shapes politics, economics and society in numerous ways and serves as a social mediator of relations between people. Contract law regulates everything from buying a bus...

, and the art
Art
Art is the product or process of deliberately arranging items in a way that influences and affects one or more of the senses, emotions, and intellect....

s, graduating as bachelier in 1735. In his later life, D'Alembert scorned the Cartesian
René Descartes
René Descartes ; was a French philosopher and writer who spent most of his adult life in the Dutch Republic. He has been dubbed the 'Father of Modern Philosophy', and much subsequent Western philosophy is a response to his writings, which are studied closely to this day...

 principles he had been taught by the Jansenists: "physical promotion, innate ideas and the vortices".

The Jansenists steered D'Alembert toward an ecclesiastical career, attempting to deter him from pursuits such as poetry
Poetry
Poetry is a form of literary art in which language is used for its aesthetic and evocative qualities in addition to, or in lieu of, its apparent meaning...

 and 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...

. Theology
Theology
Theology is the systematic and rational study of religion and its influences and of the nature of religious truths, or the learned profession acquired by completing specialized training in religious studies, usually at a university or school of divinity or seminary.-Definition:Augustine of Hippo...

 was, however, "rather unsubstantial fodder" for d'Alembert. He entered law school for two years, and was nominated avocat
Lawyer
A lawyer, according to Black's Law Dictionary, is "a person learned in the law; as an attorney, counsel or solicitor; a person who is practicing law." Law is the system of rules of conduct established by the sovereign government of a society to correct wrongs, maintain the stability of political...

in 1738.

He was also interested in 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....

 and mathematics. Jean was first registered under the name Daremberg, but later changed it to d'Alembert. The name "d'Alembert" was proposed by 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:...

 for a suspected (but non-existent) moon of Venus.

Career

In July 1739 he made his first contribution to the field of mathematics, pointing out the errors he had detected in L'analyse démontrée (published 1708 by Charles René Reynaud) in a communication addressed to the Académie des Sciences
French Academy of Sciences
The French Academy of Sciences is a learned society, founded in 1666 by Louis XIV at the suggestion of Jean-Baptiste Colbert, to encourage and protect the spirit of French scientific research...

. At the time L'analyse démontrée was a standard work, which d'Alembert himself had used to study the foundations of mathematics
Foundations of mathematics
Foundations of mathematics is a term sometimes used for certain fields of mathematics, such as mathematical logic, axiomatic set theory, proof theory, model theory, type theory and recursion theory...

. D'Alembert was also a Latin
Latin
Latin is an Italic language originally spoken in Latium and Ancient Rome. It, along with most European languages, is a descendant of the ancient Proto-Indo-European language. Although it is considered a dead language, a number of scholars and members of the Christian clergy speak it fluently, and...

 scholar of some note and worked in the latter part of his life on a superb translation of Tacitus
Tacitus
Publius Cornelius Tacitus was a senator and a historian of the Roman Empire. The surviving portions of his two major works—the Annals and the Histories—examine the reigns of the Roman Emperors Tiberius, Claudius, Nero and those who reigned in the Year of the Four Emperors...

, from which he received wide praise including that of Denis Diderot
Denis Diderot
Denis Diderot was a French philosopher, art critic, and writer. He was a prominent person during the Enlightenment and is best known for serving as co-founder and chief editor of and contributor to the Encyclopédie....

.

In 1740, he submitted his second scientific
Science
Science is a systematic enterprise that builds and organizes knowledge in the form of testable explanations and predictions about the universe...

 work from the field of fluid mechanics
Fluid dynamics
In physics, fluid dynamics is a sub-discipline of fluid mechanics that deals with fluid flow—the natural science of fluids in motion. It has several subdisciplines itself, including aerodynamics and hydrodynamics...

 Mémoire sur la réfraction des corps solides, which was recognized by Clairaut
Alexis Clairault
Alexis Claude de Clairaut was a prominent French mathematician, astronomer, geophysicist, and intellectual.-Childhood:Clairaut was born in Paris, France, where his father taught mathematics...

. In this work d'Alembert theoretically explained refraction
Refraction
Refraction is the change in direction of a wave due to a change in its speed. It is essentially a surface phenomenon . The phenomenon is mainly in governance to the law of conservation of energy. The proper explanation would be that due to change of medium, the phase velocity of the wave is changed...

.

In 1741, after several failed attempts, d'Alembert was elected into the Académie des Sciences. He was later elected to the Berlin Academy in 1746 and a Fellow of the Royal Society in 1748

In 1743 he published his most famous work, Traité de dynamique, in which he developed his own laws of motion.

When the Encyclopédie was organized in the late 1740s, d'Alembert was engaged as co-editor (for mathematics and science) with Diderot, and served until a series of crises temporarily interrupted the publication in 1757. He authored over a thousand articles for it, including the famous Preliminary Discourse. D'Alembert "abandoned the foundation of Materialism
Materialism
In philosophy, the theory of materialism holds that the only thing that exists is matter; that all things are composed of material and all phenomena are the result of material interactions. In other words, matter is the only substance...

" when he "doubted whether there exists outside us anything corresponding to what we suppose we see." In this way, D'Alembert agreed with the Idealist
Idealism
In philosophy, idealism is the family of views which assert that reality, or reality as we can know it, is fundamentally mental, mentally constructed, or otherwise immaterial. Epistemologically, idealism manifests as a skepticism about the possibility of knowing any mind-independent thing...

 Berkeley
George Berkeley
George Berkeley , also known as Bishop Berkeley , was an Irish philosopher whose primary achievement was the advancement of a theory he called "immaterialism"...

 and anticipated the Transcendental idealism
Transcendental idealism
Transcendental idealism is a doctrine founded by German philosopher Immanuel Kant in the eighteenth century. Kant's doctrine maintains that human experience of things is similar to the way they appear to us — implying a fundamentally subject-based component, rather than being an activity that...

 of Kant
Immanuel Kant
Immanuel Kant was a German philosopher from Königsberg , researching, lecturing and writing on philosophy and anthropology at the end of the 18th Century Enlightenment....

.

In 1752, he wrote about what is now called D'Alembert's paradox
D'Alembert's paradox
In fluid dynamics, d'Alembert's paradox is a contradiction reached in 1752 by French mathematician Jean le Rond d'Alembert. D'Alembert proved that – for incompressible and inviscid potential flow – the drag force is zero on a body moving with constant velocity relative to the fluid...

: that the drag
Drag (physics)
In fluid dynamics, drag refers to forces which act on a solid object in the direction of the relative fluid flow velocity...

 on a body immersed in an inviscid
Viscosity
Viscosity is a measure of the resistance of a fluid which is being deformed by either shear or tensile stress. In everyday terms , viscosity is "thickness" or "internal friction". Thus, water is "thin", having a lower viscosity, while honey is "thick", having a higher viscosity...

, incompressible fluid
Fluid
In physics, a fluid is a substance that continually deforms under an applied shear stress. Fluids are a subset of the phases of matter and include liquids, gases, plasmas and, to some extent, plastic solids....

 is zero.

In 1754, d'Alembert was elected a member of the Académie française
Académie française
L'Académie française , also called the French Academy, is the pre-eminent French learned body on matters pertaining to the French language. The Académie was officially established in 1635 by Cardinal Richelieu, the chief minister to King Louis XIII. Suppressed in 1793 during the French Revolution,...

, of which he became Permanent Secretary on 9 April 1772.

In 1757, an article by d'Alembert in the seventh volume of the Encyclopedia suggested that the Geneva clergymen had moved from Calvinism
Calvinism
Calvinism is a Protestant theological system and an approach to the Christian life...

 to pure Socinianism
Socinianism
Socinianism is a system of Christian doctrine named for Fausto Sozzini , which was developed among the Polish Brethren in the Minor Reformed Church of Poland during the 15th and 16th centuries and embraced also by the Unitarian Church of Transylvania during the same period...

, basing this on information provided by Voltaire
Voltaire
François-Marie Arouet , better known by the pen name Voltaire , was a French Enlightenment writer, historian and philosopher famous for his wit and for his advocacy of civil liberties, including freedom of religion, free trade and separation of church and state...

.
The Pastors of Geneva were indignant, and appointed a committee to answer these charges.
Under pressure from Jacob Vernes
Jacob Vernes
Jacob VernesNot to be confused with Jacob Vernet, a prominent theologian in Geneva around the same time. was a Swiss theologian and Protestant pastor in Geneva, famous for his correspondence with Voltaire and Rousseau.-Life:...

, Jean-Jacques Rousseau
Jean-Jacques Rousseau
Jean-Jacques Rousseau was a Genevan philosopher, writer, and composer of 18th-century Romanticism. His political philosophy influenced the French Revolution as well as the overall development of modern political, sociological and educational thought.His novel Émile: or, On Education is a treatise...

 and others, d'Alembert eventually made the excuse that he considered anyone who did not accept the Church of Rome to be a Socinianist, and that was all he meant. He was elected a Foreign Honorary Member of the American Academy of Arts and Sciences
American Academy of Arts and Sciences
The American Academy of Arts and Sciences is an independent policy research center that conducts multidisciplinary studies of complex and emerging problems. The Academy’s elected members are leaders in the academic disciplines, the arts, business, and public affairs.James Bowdoin, John Adams, and...

 in 1781.

Music theories

D'Alembert's first exposure to music theory was in 1749 when he was called upon to review a Mémoire submitted to the Académie by Jean-Philippe Rameau
Jean-Philippe Rameau
Jean-Philippe Rameau was one of the most important French composers and music theorists of the Baroque era. He replaced Jean-Baptiste Lully as the dominant composer of French opera and is also considered the leading French composer for the harpsichord of his time, alongside François...

. This article, written in conjunction with Diderot, would later form the basis of Rameau's 1750 treatise Démonstration du principe de l'harmonie. D'Alembert wrote a glowing review praising the author’s deductive character as an ideal scientific model. He saw in Rameau’s music theories support for his own scientific ideas, a fully systematic method with a strongly deductive synthetic structure.

Two years later in 1752, d'Alembert attempted a fully comprehensive survey of Rameau's works in his Eléments de musique théorique et pratique suivant les principes de M. Rameau. Emphasizing Rameau's main claim that music was a mathematical science that had a single principle from which could be deduced all the elements and rules of musical practice as well as the explicit Cartesian methodology employed, d'Alembert helped to popularize the work of the composer and advertise his own theories. He claims to have "clarified, developed, and simplified" the principles of Rameau, arguing that the single idea of the corps sonore was not sufficient to derive the entirety of music. D'Alembert instead claimed that three principles would be necessary to generate the major musical mode
Musical mode
In the theory of Western music since the ninth century, mode generally refers to a type of scale. This usage, still the most common in recent years, reflects a tradition dating to the middle ages, itself inspired by the theory of ancient Greek music.The word encompasses several additional...

, the minor mode, and the identity of octaves. Because he was not a musician, however, d'Alembert misconstrued the finer points of Rameau's thinking, changing and removing concepts that would not fit neatly into his understanding of music.

Although initially grateful, Rameau eventually turned on d'Alembert while voicing his increasing dissatisfaction with J. J. Rousseau's Encyclopédie articles on music. This led to a series of bitter exchanges between the men and contributed to the end of d'Alembert and Rousseau's friendship. A long preliminary discourse d'Alembert wrote for the 1762 edition of his Elémens attempted to summarize the dispute and act as a final rebuttal.

D'Alembert also discussed various aspects of the state of music in his celebrated Discours préliminaire of Diderot's Encyclopédie. D'Alembert claims that, compared to the other arts, music, "which speaks simultaneously to the imagination and the senses," has not been able to represent or imitate as much of reality because of the "lack of sufficient inventiveness and resourcefulness of those who cultivate it." He wanted musical expression to deal with all physical sensations rather than merely the passions alone. D'Alembert believed that modern (Baroque
Baroque
The Baroque is a period and the style that used exaggerated motion and clear, easily interpreted detail to produce drama, tension, exuberance, and grandeur in sculpture, painting, literature, dance, and music...

) music had only achieved perfection in his age, as there existed no classical Greek
Greeks
The Greeks, also known as the Hellenes , are a nation and ethnic group native to Greece, Cyprus and neighboring regions. They also form a significant diaspora, with Greek communities established around the world....

 models to study and imitate. He claimed that "time destroyed all models which the ancients may have left us in this genre." He praises Rameau as "that manly, courageous, and fruitful genius" who picked up the slack left by Jean-Baptiste Lully
Jean-Baptiste Lully
Jean-Baptiste de Lully was an Italian-born French composer who spent most of his life working in the court of Louis XIV of France. He is considered the chief master of the French Baroque style. Lully disavowed any Italian influence in French music of the period. He became a French subject in...

 in the French musical arts.

Personal life

D'Alembert was a participant in several Parisian salons
Salon (gathering)
A salon is a gathering of people under the roof of an inspiring host, held partly to amuse one another and partly to refine taste and increase their knowledge of the participants through conversation. These gatherings often consciously followed Horace's definition of the aims of poetry, "either to...

, particularly those of Marie Thérèse Rodet Geoffrin
Marie Thérèse Rodet Geoffrin
Marie Thérèse Rodet Geoffrin has been referred to as one of the leading female figures in the French Enlightenment. From 1750-1777, Madame Geoffrin played host to many of the most influential Philosophes and Encyclopédistes of her time...

, of the marquise du Deffand and of Julie de Lespinasse. D'Alembert became infatuated with Mlle de Lespinasse, and eventually took up residence with her.

Death

He suffered bad health for many years and his death was as the result of a urinary bladder
Urinary bladder
The urinary bladder is the organ that collects urine excreted by the kidneys before disposal by urination. A hollow muscular, and distensible organ, the bladder sits on the pelvic floor...

 illness. As a known unbeliever, D'Alembert was buried in a common unmarked grave
Unmarked grave
The phrase unmarked grave has metaphorical meaning in the context of cultures that mark burial sites.As a figure of speech, a common meaning of the term "unmarked grave" is consignment to oblivion, i.e., an ignominious end. A grave monument is a sign of respect and fondness, erected with the...

.

Legacy

In France
France
The French Republic , The French Republic , The French Republic , (commonly known as France , is a unitary semi-presidential republic in Western Europe with several overseas territories and islands located on other continents and in the Indian, Pacific, and Atlantic oceans. Metropolitan France...

, the fundamental theorem of algebra
Fundamental theorem of algebra
The fundamental theorem of algebra states that every non-constant single-variable polynomial with complex coefficients has at least one complex root...

 is known as the d'Alembert/Gauss
Carl Friedrich Gauss
Johann Carl Friedrich Gauss was a German mathematician and scientist who contributed significantly to many fields, including number theory, statistics, analysis, differential geometry, geodesy, geophysics, electrostatics, astronomy and optics.Sometimes referred to as the Princeps mathematicorum...

 theorem (an error in d'Alembert's proof was caught by Gauss).

He also created his ratio test, a test to see if a series
Series (mathematics)
A series is the sum of the terms of a sequence. Finite sequences and series have defined first and last terms, whereas infinite sequences and series continue indefinitely....

 converges.

The D'Alembertian operator, which first arose in D'Alembert's analysis of vibrating strings, plays an important role in modern theoretical physics.

While he made great strides in mathematics and physics, d'Alembert is also famously known for incorrectly arguing in Croix ou Pile that the probability
Probability
Probability is ordinarily used to describe an attitude of mind towards some proposition of whose truth we arenot certain. The proposition of interest is usually of the form "Will a specific event occur?" The attitude of mind is of the form "How certain are we that the event will occur?" The...

 of a coin landing heads increased for every time that it came up tails. In gambling
Gambling
Gambling is the wagering of money or something of material value on an event with an uncertain outcome with the primary intent of winning additional money and/or material goods...

, the strategy of decreasing one's bet the more one wins and increasing one's bet the more one loses is therefore called the D'Alembert system, a type of martingale
Martingale (probability theory)
In probability theory, a martingale is a model of a fair game where no knowledge of past events can help to predict future winnings. In particular, a martingale is a sequence of random variables for which, at a particular time in the realized sequence, the expectation of the next value in the...

.

Fictional portrayal

Diderot portrayed "Le rêve de D'Alembert" ("D'Alembert's Dream"), written after the two men became estranged. It depicts D'Alembert ill in bed, conducting a debate on materialist philosophy in his sleep.

The Andrew Crumey
Andrew Crumey
Andrew Crumey is a novelist and former literary editor of the Scotland on Sunday newspaper. He was born in Kirkintilloch, north of Glasgow, Scotland. He graduated with First Class Honours from the University of St Andrews and holds a PhD in theoretical physics from Imperial College, London. In...

 novel "D'Alembert's Principle" (1996) takes its title from D'Alembert's principle
D'Alembert's principle
D'Alembert's principle, also known as the Lagrange–d'Alembert principle, is a statement of the fundamental classical laws of motion. It is named after its discoverer, the French physicist and mathematician Jean le Rond d'Alembert...

 in physics. Its first part describes D'Alembert's life and his infatuation with Julie de Lespinasse.

See also

  • d'Alembert's formula
  • Gambler's fallacy
    Gambler's fallacy
    The Gambler's fallacy, also known as the Monte Carlo fallacy , and also referred to as the fallacy of the maturity of chances, is the belief that if deviations from expected behaviour are observed in repeated independent trials of some random process, future deviations in the opposite direction are...

  • Liberalism
    Liberalism
    Liberalism is the belief in the importance of liberty and equal rights. Liberals espouse a wide array of views depending on their understanding of these principles, but generally, liberals support ideas such as constitutionalism, liberal democracy, free and fair elections, human rights,...

  • List of liberal theorists

External links

The source of this article is wikipedia, the free encyclopedia.  The text of this article is licensed under the GFDL.
 
x
OK