Joseph Fourier

Jean-Baptiste Joseph Fourier was a French mathematician and physicist born on March 21, 1768, in Auxerre, Burgundy. He is best known for his important work in mathematics, especially for starting the study of Fourier series. This work later grew into Fourier analysis and harmonic analysis, which help solve many problems in science and engineering.

Fourier’s ideas have been used to understand heat transfer and vibrations. Two important concepts named after him are the Fourier transform and Fourier’s law of conduction. Besides his work in mathematics and physics, Fourier is also recognized for discovering the greenhouse effect, which helps explain how Earth’s atmosphere traps heat from the sun.

He lived until May 16, 1830, and his discoveries continue to be important in many areas of science and technology today.

Biography

Joseph Fourier was born in 1768 in Auxerre, France, the son of a tailor. When he was nine, he lost his parents. He was educated by a local religious group and later taught mathematics in the army, even though he wasn't from a noble family. During the French Revolution, he helped lead his community and was briefly jailed but later became a teacher at a famous school.

Fourier traveled with Napoleon to Egypt in 1798, where he gave advice and helped set up a research institute. After returning to France, he became the leader of a region near Grenoble and worked on building roads. It was here that he started studying how heat moves through solids. Later, he became an important leader in the French Academy of Sciences. Fourier never married and passed away in 1830 after some health problems. He was buried in Paris, and his name is even written on the Eiffel Tower today.

The Analytic Theory of Heat

In 1822, Fourier shared his big ideas about how heat moves in his book The Analytical Theory of Heat. He used a rule from Newton about how heat moves between things that are close in temperature.

In his book, Fourier made three big discoveries. First, he showed that math can describe things that change suddenly, using special patterns with sines. Second, he talked about making sure math equations make sense by matching up sizes. Third, he created a special math rule to explain how heat spreads out, which is still taught today.

His work helped other mathematicians develop new theories and also talked about special math patterns years before another scientist studied them.

Roots of polynomials

When he was young, Joseph Fourier found a special way to understand how many positive answers a math problem might have. Later, he worked on a difficult math challenge about finding the real answers to polynomial equations, but he didn’t finish it. This work was put together and shared after his time by another scientist, Claude-Louis Navier, in 1831. Fourier’s ideas were very new and important, especially one big rule he shared in 1820 about real answers in these math problems. Another mathematician, François Budan, had shared similar ideas a little earlier, in 1807 and 1811. A full answer to this challenge was finally completed in 1829 by Sturm.

Discovery of the greenhouse effect

In the 1820s, a scientist named Joseph Fourier tried to figure out why Earth is warmer than it should be just from the Sun’s heat. He thought maybe something in our air was trapping heat, like how glass keeps a greenhouse warm. Although he was not exactly right about why, his idea was the first step in understanding how Earth’s air helps keep the planet warm.

Works

Here is a list of important works by Joseph Fourier:

• "Sur l'usage du théorème de Descartes dans la recherche des limites des racines". Paris: Firmin Didot Père et Fils. 1822. OCLC (https://search.worldcat.org/oclc/2688081).
  • Théorie analitique de la chaleur (in French). Vol. 1. Paris: Gauthier-Villars. 1888.
• "Remarques Générales Sur Les Températures Du Globe Terrestre Et Des Espaces Planétaires". Annales de Chimie et de Physique. 27: 136–167. 1824a.
• Gay-Lussac, Joseph Louis; Arago, François, eds. (1824b). "Resume theorique des Proprietes de la chaleur rayonette". Annales de Chimie et de Physique. 27. Paris: 236–281.
• Mémoire sur la température du globe terrestre et des espaces planétaires. Vol. 7. Mémoires de l'Académie Royale des Sciences. 1827a. pp. 569–604. Translation by W M Connolley
• Mémoire sur la distinction des racines imaginaires, et sur l'application des théorèmes d'analyse algébrique aux équations transcendantes qui dépendant de la théorie de la chaleur. Vol. 7. Memoirs of the Royal Academy of Sciences of the Institut de France. 1827b. pp. 605–624.
• Analyse des équations déterminées on 30 September 2011. Retrieved 20 April 2011.
• Remarques générales sur l'application du principe de l'analyse algébrique aux équations transcendantes. Vol. 10. Paris: Memoirs of the Royal Academy of Sciences of the Institut de France. 1827d. pp. 119–146.
• Mémoire d'analyse sur le mouvement de la chaleur dans les fluides. Vol. 12. Paris: Memoirs of the Royal Academy of Sciences of the Institut de France. 1833. pp. 507–530.
• Rapport sur les tontines. Vol. 5. Paris: Memoirs of the Royal Academy of Sciences of the Institut de France. 1821. pp. 26–43.