It is rare to meet someone who has made great contributions in various fields. Such polymaths, those who possess knowledge in a wide range of fields, are always rare. Frenchman Dominique François Jean Arago is one such person in this world who in his eventful life wore the hat of a physicist, mathematician, astronomer and politician. did.

Born in Estergel, Roussillon, France, in 1786, Arago was one of eleven children. Arago, who was educated at the City University of Perpignan, was inclined to mathematics from an early age. He entered the École his polytechnique in Paris and became professor of analytic geometry at the young age of 23, succeeding the French mathematician Gaspard Monge.

love for optics

He made his first major contribution to science in the next decade. Arago, working with the French engineer Augustin-Jean Fresnel, found that two rays polarized in the plane can interfere with each other, but two rays polarized perpendicular to each other cannot. was able to show This research led to the discovery of the law of polarization.

Portrait of François Arago by French painter Carl von Steuben. | | Photo credit: Wikimedia Commons

In 1820, Arago took a brief break from optical research to greatly expand his electromagnetic theory. Invited to Geneva to witness Danish physicist Hans Christian Oersted’s experiment combining electricity and magnetism, Arago was immediately converted and took a great interest in the subject.

Besides repeating Geneva’s experiments at the Paris Academy, Arago also conducted experiments himself. The temporary magnetization attracted the iron powder, and when the current stopped, the iron powder fell. He published this development of electromagnetism on his September 25, 1820.

electromagnetic induction

Shortly thereafter, Arago discovered the principle of magnetism generated by rotation of a non-magnetic conductor. He was able to show that the rotation of a non-magnetic metallic substance such as copper produces a magnetic effect because it produces a rotation of a magnetic needle suspended above it.British scientist Michael Faraday It took him ten more years before he explained these using his theory of electromagnetic induction in 1831.

From 1830 Arago was director of the Paris Observatory. As an astronomer, he was one of the first to explain stellar scintillation using interference phenomena. He was also able to provide important inspiration to young astronomers, including the Frenchman Urban Le Verrier.

“With his pen tip”

In 1845, Arago suggested to his disciple that he investigate anomalies in the motion of Uranus. Arago summed it up best when he called Le Verrier a man who “discovered planets with the tip of a pen.” Arago sided with Le Verrier in the dispute between Le Verrier and British astronomer John Couch Adams over the priority of discovering Neptune, and even suggested that the planet be named after Le Verrier.

In his scientific endeavours, Arago also found time to support the ideas of others. French photographer Louis Daguerre was having trouble selling his daguerreotype process, but was able to attract the attention of Arago, who was the executive director of the French Academy of Sciences.

photo advocate

Arago arranged the first public exhibition of the daguerreotype in January 1839 and used the topic it generated in his lobbying efforts. He lobbied the French parliament to grant pensions to Daguerre and Isidore Niépce, sons of the French inventor Nicephore Niépce, so that every step of the photographic process could be made public. Arago said, “France should honor the whole world with this discovery which may greatly contribute to the progress of art and science,” and the technical details were published on August 19, 1839. (hence celebrated as World Photography Day).

The study of optics and light lies deep in Arago’s mind, devising an experiment to prove the wave theory of light. In 1838 he described a test to compare the speed of light in air and in water or glass. However, due to the elaborate preparations required for the experiment and his own poor eyesight, it was never carried out. Shortly before Arago’s death, French physicists Hippolyte Fizeau and Léon Foucault demonstrated the retardation of light in a dense medium by improving the method proposed by Arago.

Having devoted much of his time to science, he was able to devote himself to other goals as a politician. After his July Revolution of 1830 and until his death in 1853, Arago acted as a politician, delivering influential speeches on educational reform, press freedom, and the application of scientific ideas to progress. rice field. After his February Revolution of 1848, he served as Minister of War and Minister of the Navy, using that power to abolish slavery in the French colonies. Arago’s influential life highlights the fact that he has always had the ability to inspire and inspire those around him and the general public, both in the realms of science and politics.