French politician who prefers to be a scientist: Who is François Arago?

(1786-1853) French scientist and politician. He worked in the field of light and magnetism and took part in the provisional government established in France after the February Revolution of 1848. Dominique François Jean Arago was born on February 26, 1786 in Estagel in Perpignan in the Pyrenees-Orientales region. After completing his primary and secondary education in this city, he graduated from Ecole Polytechnique in Paris. With the help of Laplace, he was made secretary of the Department of Longitudes. In 1806, he went to Spain to measure the meridian arc with Biot, who was his assistant.

Dominique François Jean Arago (26 February 1786 – 2 October 1853), was a French mathematician, physicist, astronomer, freemason, supporter of the Carbonari revolutionaries and politician.

During this period, the two countries were at odds with Napoleon Bonaparte's desire to make his brother Joseph king of Spain. Sometime after Biot's return to France, Arago was accused of espionage. After being imprisoned in Palma for three months, he secretly reached Marseille via Algiers in 1809. A few months later, he was elected a member of the French Academy of Sciences, replacing Lalande. In the same year, he was appointed to the analytical geometry chair vacated by Gaspard Monge at the Ecole Polytechnique and taught analysis and geodesy at this school for about twenty years. In 1830, the Academy of Sciences gave Arago the post of the permanent secretary, which was vacated by Fourier's death. In the same year, he became the director of the Paris Observatory and the Department of Longitudes and was active in the field of politics in the 1830 and 1848 revolutions, and during the reign of Napoleon III, he devoted all his time to scientific studies. He died in Paris on October 2, 1853.

One of Arago's three brothers, Jean (17881836), was a general who fought for Mexico in the Mexican war of independence; Jacques Etienne Victor (1790-1855) is a famous writer for his travel notes; Etienne (1802-1892) was a revolutionary politician and writer who participated in the 1849 uprising. François Arago's son, François Victor Emmanuel, was a staunch republican like his father and held various government positions after the reign of Napoleon III.

The period in which Arago lived was a period when France witnessed intense social and political events. During the "July Monarchy" period, which started with Louis-Philippe's appointment to the kingdom in July 1830, Arago was elected as a deputy from the Pyrenees of the East. During this period, the pressure applied to the press and the opposition led to occasional uprisings, but these were suppressed before they grew. By 1847, the widespread economic crisis in France and Europe resulted in the bourgeoisie's refusal to support the king, and in 1848 the uprising of radical sections of society.

Arago served as minister of naval and warfare in the provisional government established in February 1848. The first act of the moderate republican-dominated provisional government was to proclaim the II Republic and give all citizens the right to vote; it was contented with bringing temporary solutions to worker demands. The government also outlawed slavery in the French colonies, out of concern not to contradict the 1789 Revolution, and for economic reasons. Arago was among those who signed this resolution. Arago, who also took part in the constituent assembly formed to hold general elections, was the representative of the bourgeoisie in the moderate republican wing and attracted attention with his speaking ability.

While Arago was considering becoming a soldier at first, he started to work in the Department of Longitudes with the support of Laplace, who sensed his talent in scientific matters. The measurement of the meridian arc, carried out under the direction of this office, was his first important work. Continuing their joint work after that, Arago and Biot calculated the refractive index of gases, the density of air, and some gases together.

At the same time, Arago became interested in Young's wave theory to explain the propagation of light. He eventually became one of the most ardent proponents of wave theory; siding with Fresnel, who sought to develop this theory, he vehemently opposed Laplace, Biot, and Poisson. The theory, which was supported by these three physicists and which claimed that light consisted of particles emitted by a heated body, was insufficient to explain some events that the wave theory could explain, such as interference.

Apart from his work in optics, Arago also made valuable contributions to physics on magnetism. Arago began to study this phenomenon in 1820 when the Danish physicist Oersted explained that a wire through which an electric current was passed creates a magnetic field around it. In the same year, he showed that when an electric current is passed through a copper spiral, the surrounding iron shavings adhere to the wire and separate from the wire when the current is cut off. Working with Ampere, he succeeded in obtaining permanent magnetism in iron with an electric current. In 1824, he observed that a rotating copper disk, through which an electric current was passed, rotated the magnetic indicator on it. In 1825, the Royal Society of London awarded Arago the Copley Medal for discovering this phenomenon of rotational magnetism and the first artificial magnet, whose rules Foucault would later establish.

Continuing his astronomy studies during his long tenure at the Paris Observatory, Arago studied the solar chromosphere in 1840. He took pictures of the Sun for the first time, developed a method of measuring the diameter of planets by avoiding light deflection, and revealed the relationship between magnetic storms and aurora. As a scientist, he was in favor of communicating all developments in science to the public; The lectures he gave at the observatory from 1812 to 1845 found a wide audience.

Even in his intense political life between 1830-1850, Arago's scientific studies, which he continued without interruption, are of a quality that will be the basis for new developments in many branches of physics. Especially his research on polarization brought new dimensions to wave theory and his studies on magnets to electromagnetism.