Andre-Marie Ampère was a French physicist who founded and named the science of electrodynamics, now known as electromagnetism. His name endures in everyday life in the ampere, the unit for measuring electric current.
Background
Andre-Marie Ampere was born on 20 January 1775 to Jean-Jacques Ampere, a prosperous businessman, and Jeanne Antoinette Desutières-Sarcey Ampère, during the height of the French Enlightenment. He spent his childhood and adolescence at the family property at Poleymieux-au-Mont-d'Or near Lyon. His mother was a devout woman, so Ampère was also initiated into the Catholic faith along with Enlightenment science. Ampère’s father was called into public service by the new revolutionary government, becoming a justice of the peace in a small town near Lyon. Yet when the Jacobin faction seized control of the Revolutionary government in 1792, Jean-Jacques Ampère resisted the new political tides, and he was guillotined on November 24, 1793, as part of the Jacobin purges of the period.
Education
Ampère’s father was an admirer of the philosophy of Jean-Jacques Rousseau, whose theories of education, as outlined in his treatise Émile, were the basis of Ampère’s education. He argued that young boys should avoid formal schooling and pursue instead an "education direct from nature." Ampère’s father actualized this ideal by allowing his son to educate himself within the walls of his well-stocked library. French Enlightenment masterpieces such as Georges-Louis Leclerc, Comte de Buffon’s Histoire Naturelle, générale et particulière (begun in 1749) and Denis Diderot and Jean Le Rond d’Alembert’s Encyclopédie (volumes added between 1751 and 1772) thus became Ampère’s schoolmasters.
Aged 13, André-Marie began a serious study of mathematics using books in his father’s library. He submitted a paper about conic sections to the Academy of Lyon, but it was rejected. The rejection spurred him into working harder than ever. His father bought him specialist books to help him improve. He also took his son into Lyon, where Abbot Daburon gave him lessons in calculus – the first formal lessons André-Marie ever had.
Having taken his son for formal mathematics lessons, his father also took him to Lyon’s college to attend some physics lectures, which resulted in André-Marie beginning to read physics books as well as mathematics books.
In 1789, when André-Marie was 14, the French Revolution began. In 1793, the Jacobin faction of the revolution guillotined his father. (The great chemist Antoine Lavoisier was guillotined by revolutionaries in 1794.) Mercifully, André-Marie, studying mathematics and science on the family estate, survived the revolution’s reign of terror. He was devastated by his father’s death and abandoned his studies for a year.
Career
André-Marie Ampère took his first regular job in 1799 as a modestly paid mathematics teacher, which gave him the financial security to marry and father his first child, Jean-Jacques, the next year. Ampère’s maturation corresponded with the transition to the Napoleonic regime in France, and the young father and teacher found new opportunities for success within the technocratic structures favored by the new French emperor.
In 1802 Ampère was appointed a professor of physics and chemistry at the École Centrale in Bourg-en-Bresse. He used his time in Bourg to research mathematics, producing Considérations sur la théorie mathématique de jeu (1802; “Considerations on the Mathematical Theory of Games”), a treatise on the mathematical probability that he sent to the Paris Academy of Sciences in 1803. After the death of his wife in July 1803, Ampère moved to Paris, where he assumed a tutoring post at the new École Polytechnique in 1804. Despite his lack of formal qualifications, Ampère was appointed a professor of mathematics at the school in 1809. In addition to holding positions at this school until 1828, in 1819 and 1820 Ampère offered courses in philosophy and astronomy, respectively, at the University of Paris. In 1824, Ampère was appointed to the Chair of Experimental Physics at the Collège de France in Paris, which he occupied for the rest of his life.
In 1814 Ampère was invited to join the class of mathematicians in the new Institut Impériale, the umbrella under which the reformed state Academy of Sciences would sit. Ampère engaged in a diverse array of scientific inquiries during these years leading up to his election to the academy-writing papers and engaging in topics ranging from mathematics and philosophy to chemistry and astronomy. Such breadth was customary among the leading scientific intellectuals of the day.
In 1820 Ampère’s friend and eventual eulogist François Arago demonstrated before the members of the French Academy of Sciences the surprising discovery of Danish physicist Hans Christiaan Orsted that a magnetic needle is deflected by an adjacent electric current. Ampère was well prepared to throw himself fully into this new line of research.
In 1827 Ampère published his magnum opus, Mémoire sur la théorie mathématique des phénomènes électrodynamiques uniquement déduite de l’experience (Memoir on the Mathematical Theory of Electrodynamic Phenomena, Uniquely Deduced from Experience), the work that coined the name of his new science, electrodynamics, and became known ever after as its founding treatise. In recognition of his contribution to the making of modern electrical science, an international convention signed in 1881 established the ampere as a standard unit of electrical measurement, along with the coulomb, volt, ohm, and watt, which are named, respectively, after Ampère’s contemporaries Coulomb, Alessandro Volta of Italy, Georg Ohm of Germany, and James Watt of Scotland.
The 1827 publication of Ampère’s synoptic Mémoire brought to a close his feverish work over the previous seven years on the new science of electrodynamics. The text also marked the end of his original scientific work.
His health began to fail, and he died in 1836 while performing a university inspection, decades before his new science was canonized as the foundation stone for the modern science of electromagnetism.
André-Marie Ampère made the revolutionary discovery that a wire carrying electric current can attract or repel another wire next to it that’s also carrying electric current. The attraction is magnetic, but no magnets are necessary for the effect to be seen. He went on to formulate Ampere’s Law of electromagnetism and produced the best definition of electric current of his time.
Ampère also proposed the existence of a particle we now recognize as the electron, discovered the chemical element fluorine, and grouped elements by their properties over half a century before Dmitri Mendeleev produced his periodic table.
In recognition of his contribution to the creation of modern electrical science, an international convention, signed at the 1881 International Exposition of Electricity, established the ampere as a standard unit of electrical measurement, along with the coulomb, volt, ohm, and watt, which are named, respectively, after Ampere's contemporaries Charles-Augustin de Coulomb of France, Alessandro Volta of Italy, Georg Ohm of Germany, and James Watt of Scotland. Ampère's name is one of the 72 names inscribed on the Eiffel Tower.
Several items are named after Ampere; many streets and squares, schools, a Lyon metro station, and an electric ferry in Norway.
Ampère's mother was a devout woman, so Ampère was also initiated into the Catholic faith along with Enlightenment science.
Views
In 1800, while Ampère worked as a private tutor in Lyon, Alessandro Volta had invented the electric battery. One result of this was that for the first time, scientists could produce a steady electric current. In April 1820, Hans Christian Oersted discovered that the flow of electric current in a wire could deflect a nearby magnetic compass needle. Oersted had discovered a link between electricity and magnetism - electromagnetism.
In September 1820, François Arago demonstrated Oersted’s electromagnetic effect to France’s scientific elite at the French Academy in Paris. Ampère was present, having been elected to the Academy in 1814. Ampère was fascinated by Oersted’s discovery and decided he would try to understand why electric current produced a magnetic effect.
Ampère began by repeating Oersted’s work, and before the end of September 1820, had discovered his own: he found that if electric current flows in the same direction in two nearby parallel wires, the wires attract one another; if electric currents flow in opposite directions the wires repel one another.
Ampère had discovered something amazing: he had produced magnetic attraction and repulsion in the complete absence of any magnets. All of the magnetism was generated electrically. He called this new field electrodynamics. (Today electrodynamics and electromagnetism are regarded as the same field.)
Ampère then brilliantly found an equation connecting the size of a magnetic field to the electric current that produces it. This equation, known as Ampère’s circuital law, is highly mathematical, requiring university-level mathematics to use and understand.
This equation applies to situations where the electric current is constant. Over 40 years later, James Clerk Maxwell modified this equation so it would also apply to situations in which the current is not constant. In this form, it became one of his four famous equations establishing that light is an electromagnetic wave.
To explain the relationship between electricity and magnetism, Ampère proposed the existence of a new particle responsible for both of these phenomena - the electrodynamic molecule, a microscopic charged particle we can think of as a prototype of the electron. Ampère correctly believed that huge numbers of these electrodynamic molecules were moving in electric conductors, causing electric and magnetic phenomena.
Ampère did not restrict his interests to mathematics and physics; they were wide-ranging and included philosophy and astronomy. He was particularly interested in chemistry. Preceding his work in electromagnetism, he made significant contributions to chemistry.
Ampère discovered and named the element fluorine. In 1810, he proposed that the compound we now call hydrogen fluoride consisted of hydrogen and a new element: the new element had similar properties to chlorine he said. He and Humphry Davy, who was British, entered into correspondence (even though France and Britain were at war). Ampère proposed that fluorine could be isolated by electrolysis, which Davy had previously used to discover elements such as sodium and potassium.
It was only in 1886 that French chemist Henri Moissan finally isolated fluorine. He achieved this using electrolysis, the method Ampère had recommended.
In 1816, 53 years before Dmitri Mendeleev published his periodic table, Ampère proposed that the chemical elements - 48 were known at that time - should be grouped according to their properties. He made several mistakes but successfully grouped: the alkali metals (sodium and potassium), the alkali earth metals (magnesium, calcium, strontium, and barium), the halogens (chlorine, fluorine, and iodine). He was also moving in the right direction by identifying similarities in the noble metals: rhodium, palladium, iridium, platinum, and gold (unfortunately, Ampère excluded silver from this group, grouping it instead with mercury, lead, and bismuth); first series transition elements: iron, cobalt, nickel, copper, (although uranium was incorrectly included); transition elements: niobium, molybdenum, chromium, and tungsten.
Ampère did not name the groups as they are named above, such as the noble metals and transition elements - these are modern names.
Mendeleev had an advantage over Ampère in that 65 elements were known to him, allowing him to see patterns more easily. Importantly, Mendeleev also paid attention to atomic weights, while Ampère did not. To be fair to Ampère, we need to remember that J. J. Berzelius published the first reasonably accurate list of atomic weights in 1828, 12 years after Ampère’s elements work.
The International System of Units' unit for electric current is the ampere or amp (symbol A), named in Ampère’s honor. It was Ampère who first defined electric current as a "circulation of electric fluid in a closed circuit."
Ampère set to work developing a mathematical and physical theory to understand the relationship between electricity and magnetism. Extending Orsted’s experimental work, Ampère showed that two parallel wires carrying electric currents repel or attract each other, depending on whether the currents flow in the same or opposite directions, respectively. He also applied mathematics in generalizing physical laws from these experimental results. Most important was the principle that came to be called Ampère’s law, which states that the mutual action of two lengths of current-carrying wire is proportional to their lengths and the intensities of their currents. Ampère also applied this same principle to magnetism, showing the harmony between his law and French physicist Charles Augustin de Coulomb’s law of magnetic action. Ampère’s devotion to, and skill with, experimental techniques anchored his science within the emerging fields of experimental physics.
Ampère also offered a physical understanding of the electromagnetic relationship, theorizing the existence of an “electrodynamic molecule” (the forerunner of the idea of the electron) that served as the constituent element of electricity and magnetism. Using this physical understanding of electromagnetic motion, Ampère developed a physical account of electromagnetic phenomena that was both empirically demonstrable and mathematically predictive.
Quotations:
"Ordinarily logic is divided into the examination of ideas, judgments, arguments, and methods. The two latter are generally reduced to judgments, that is, arguments are reduced to apodictic judgments that such and such conclusions follow from such and such premises, and method is reduced to judgments that prescribe the procedure that should be followed in the search for truth."
"The future science of government should be called “la cybernétique”."
"There is synthesis when, in combining therein judgments that are made known to us from simpler relations, one deduces judgments from them relative to more complicated relations. There is analysis when from a complicated truth one deduces more simple truths."
Membership
In 1827 Ampère was elected a Foreign Member of the Royal Society and in 1828, a foreign member of the Royal Swedish Academy of Science. He also was a member of the Royal Academy of Science, Letters and Fine Arts of Belgium.
The Royal Society
,
United Kingdom
1827
Royal Swedish Academy of Science
,
Sweden
1828
Royal Academy of Science, Letters and Fine Arts of Belgium
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Belgium
Personality
Quotes from others about the person
“The experimental investigation by which Ampère established the law of the mechanical action between electric currents is one of the most brilliant achievements in science. The whole theory and experiment seem as if it had leaped, full grown and full armed, from the brain of the ‘Newton of Electricity’. It is perfect in form and unassailable in accuracy, and it is summed up in a formula from which all the phenomena may be deduced, and which must always remain the cardinal formula of electrodynamics.” - James Clerk Maxwell.
"True greatness is when your name is like ampere, watt, and fourier - when it's spelled with a lower case letter." - Richard Hamming.
"Always preoccupied with his profound researches, the great Newton showed in the ordinary-affairs of life an absence of mind which has become proverbial. It is related that one day, wishing to find the number of seconds necessary for the boiling of an egg, he perceived, after waiting a minute, that he held the egg in his hand, and had placed his second's watch (an instrument of great value on account of its mathematical precision) to boil!
"The absence of mind reminds one of the mathematician Ampere, who one day, as he was going to his course of lectures, noticed a little pebble on the road; he picked it up, and examined with admiration the mottled veins. All at once the lecture which he ought to be attending to returned to his mind; he drew out his watch; perceiving that the hour approached, he hastily doubled his pace, carefully placed the pebble in his pocket, and threw his watch over the parapet of the Pont des Arts." - Camille Flammarion.
"Ampère was a mathematician of various resources and I think might rather be called eccentric ... than original. He was as it was always mounted upon a hobby horse of a monstrous character pushing the most remote and distant analogies. This hobby horse was sometimes like that of a child's made of heavy wood, at other times it resembled those shapes used in the theatre and at other times it was like a hypogrif in a pantomime de imagie. He had a sort of faith in animal magnetism and has published some refined and ingenious memoirs to prove the identity of electricity and magnetism but even in these views, he is rather as I said before excentric than original. He has always appeared to me to possess a very discursive imagination and but little accuracy of observation or acuteness of research." - June Zimmerman Fullmer.
Connections
In 1799, aged 24, Ampère married 25-year-old Catherine-Antoinette Carron, who was usually called Julie. A year later, their son Jean-Jacques was born - he was named in memory of Ampère’s beloved father. Tragedy struck Ampère when, after less than four years of marriage, Julie died in 1803 of abdominal cancer.
Ampère got married again in 1806, to Jeanne-Françoise Potot. The couple quickly realized their marriage had been a mistake. Their daughter Albine was born in 1807, and the couple legally separated in 1808. Albine came to live with her father and his younger sister Josephine.
