The name of Étienne-Louis Malus remains one of 72 inscriptions on the Eiffel Tower, marking his contributions to the analytical study of optics. Born in Paris in 1775, he served as a military engineer and mathematician within the French Armed Forces, dedicating his short career to the mathematical understanding of light and the development of ray systems.
Military and Academic Formation
Malus received his technical training at several prominent French institutions. Between 1794 and 1796, he attended the École polytechnique before moving to the École d'application de l'artillerie et du génie in Metz. His education also included study at the École royale du génie de Mézières, where he was instructed by Gaspard Monge. These formative years laid the groundwork for his career as a military officer and an expert in physical analysis.
Twenty questions, eight minutes on the clock, and a percentile measured against everyone who has taken it. No sign-up.
Take the IQ test →Expeditions and Professional Recognition
During his service with the French Armed Forces, Malus participated in Napoleon's Egyptian campaign between 1798 and 1801, serving as a member of the mathematics section of the Institut d'Égypte. His later professional life was marked by significant accolades. In 1810, he became a member of the French Academy of Sciences and was awarded the Rumford Medal by the Royal Society of London. That same year, he received the Grand prix des sciences mathématiques.
Contributions to Optical Science
Malus focused his mathematical research on the study of light, specifically geometric ray systems. He is credited with the discovery of the polarization of light by reflection, a phenomenon he first observed while examining sunlight reflected from the windows of the Luxembourg palace. He articulated these findings in his 1810 theory of double refraction in crystals. His name is associated with the Malus–Dupin theorem and Malus's law, which determines the intensity of light passing through a polarizer.
Final Years
Despite his scientific output, Malus suffered from poor health for several years, a condition exacerbated by illnesses contracted during his time in Egypt. By 1812, his struggle with tuberculosis rendered him unable to continue his work. He died in Paris at the age of 36. His remains were interred at the Père Lachaise Cemetery, ending a brief but influential career in French physics.
Fast facts
- Born: 1775, Paris
- Died: 1812, Paris
- Rank: Lieutenant Colonel
- Education: École polytechnique
- Key Award: Rumford Medal (1810)
- Notable Contribution: Malus's law
- Burial: Père Lachaise Cemetery
- Professional Membership: French Academy of Sciences
Questions readers ask
What is the Malus–Dupin theorem?
It is a mathematical theorem regarding light rays, demonstrating that rays emitted from a point source and reflected remain normal to a common surface.
How did Malus discover polarization?
He observed sunlight reflected from the windows of the Luxembourg palace through a doubly refracting quartz prism and noted that the rays disappeared as the prism rotated.
Achievements
- Rumford Medal — 1810
- Notable work: Malus–Dupin theorem
- Notable work: Malus' law
- Held posts at École polytechnique and French Armed Forces
- Fields: optics
.jpg)
