iiinova — where your digital self keeps evolving

François Levrier @francoislevrier.bsky.social · 22h

Svante Arrhenius died #OTD in 1927. One of the founders of physical chemistry, he gave the first modern definition of acids and bases. The Arrhenius equation describes reaction rates, introducing the concept of activation energy. en.wikipedia.org/wiki/Svante_...

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François Levrier @francoislevrier.bsky.social · 01/10/2026

Otto Frisch was born #OTD in 1904. An Austrian-born British physicist, he and his aunt Lise Meitner explained the process of nuclear fission observed by Hahn and Strassmann. He outlined the process for producing an atomic bomb. en.wikipedia.org/wiki/Otto_Ro...

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François Levrier @francoislevrier.bsky.social · 30/09/2026

Charles Francis Richter died #OTD in 1985. His childhood interest in astronomy led him to call « magnitude » the intensity of earthquakes that the scale which bears his name measures. en.wikipedia.org/wiki/Charles...

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François Levrier @francoislevrier.bsky.social · 30/09/2026

Jean Perrin was born #OTD in 1870. Famous for experiments on Brownian motion, he was also a major advocate for the advancement of science, leading to the creation of Observatoire de Haute-Provence, Palais de la Découverte, and CNRS. en.wikipedia.org/wiki/Jean_Ba...

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François Levrier @francoislevrier.bsky.social · 29/09/2026

Enrico Fermi was born #OTD in 1901. An Italian-born American physicist who received the 1938 Nobel Prize for induced radioactivity. He was a pioneer of the atomic age, demonstrating the first self-sustaining nuclear chain in 1942. en.wikipedia.org/wiki/Enrico_...

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François Levrier @francoislevrier.bsky.social · 28/09/2026

Martin David Kruskal was born #OTD in 1925. A mathematician and physicist, he made vast contributions to the study of instabilities in plasmas, to general relativity, and to solitary wave (« soliton ») phenomena. en.wikipedia.org/wiki/Martin_...

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François Levrier @francoislevrier.bsky.social · 27/09/2026

Do you have 17 hours of spare time ? They would be very well spent on this "Particle Physics Marathon" by Kamil Laurent. An excellent introduction to the topic if you have basic knowledge of quantum physics and Lagrangian mechanics. youtu.be/YFiQIZOM2fw?...

youtu.be

Particle Physics in 17 Hours

YouTube video by Kamil Laurent

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François Levrier @francoislevrier.bsky.social · 27/09/2026

Martin Ryle was born #OTD in 1918. In the aftermath of WWII, he was a pioneer of interferometry and aperture synthesis in radio astronomy with the Cambridge group. For this he received the 1974 Nobel Prize in Physics. en.wikipedia.org/wiki/Martin_...

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François Levrier @francoislevrier.bsky.social · 26/09/2026

À l'occasion de ses 35 ans, l'association du centre historique de la diffusion radiophonique d'Issoudun a rendu hommage à mon père, Philippe Levrier, en donnant son nom à leur salle d'exposition, au sein du bâtiment de TDF dont il avait empêché la destruction.

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François Levrier @francoislevrier.bsky.social · 25/09/2026

Paul Ehrenfest died #OTD in 1933. An Austrian physicist, he made vast contributions to statistical mechanics and quantum physics. The Ehrenfest theorem states that expectation values of quantum operators behave classically. en.wikipedia.org/wiki/Paul_Eh...

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François Levrier @francoislevrier.bsky.social · 25/09/2026

Johann Heinrich Lambert died #OTD in 1777. A Swiss mathematician and physicist who made important contributions to optics, such as the Beer-Lambert law of attenuation, he also was a pioneer of map projections. en.wikipedia.org/wiki/Johann_...

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François Levrier @francoislevrier.bsky.social · 25/09/2026

Ole Rømer was born #OTD in 1644. He timed Io’s eclipses in Jupiter’s shadow from different points on the Earth’s orbit, allowing Huygens and others to determine a value of approximately 212000 km/s for the speed of light. en.wikipedia.org/wiki/Ole_R%C...

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François Levrier @francoislevrier.bsky.social · 24/09/2026

Adriaan Fokker died #OTD in 1972. A Dutch physicist and cousin of aircraft manufacturer Anthony Fokker, he co-derived the Fokker-Planck equation describing the time evolution of distributions of particles under drag and diffusion. en.wikipedia.org/wiki/Adriaan...

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François Levrier @francoislevrier.bsky.social · 24/09/2026

Charlotte Moore Sitterly was born #OTD in 1898. She worked extensively on the chemical composition of the Sun, based on spectroscopic data. In particular, she identified technetium, providing the first naturally occurring detection of that element. en.wikipedia.org/wiki/Charlot...

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François Levrier @francoislevrier.bsky.social · 23/09/2026

Charles K. Kao died #OTD in 2018. His work on optical fibers proved that attenuation could be significantly reduced by using high-purity fused silica, opening the path to the wide use of this technology in modern communications. en.wikipedia.org/wiki/Charles...

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François Levrier @francoislevrier.bsky.social · 23/09/2026

Urbain Le Verrier died #OTD in 1877. He predicted the existence of Neptune in 1846 from the perturbation of the orbit of Uranus. Adams made the same computation independently, and Galle was the first to observe the planet. en.wikipedia.org/wiki/Urbain_...

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François Levrier @francoislevrier.bsky.social · 23/09/2026

Hippolyte Fizeau was born #OTD in 1819. Working together with L. Foucault, and then as his rival, he determined the speed of light in air to within five percent, improving on Rømer’s much earlier determination. en.wikipedia.org/wiki/Hippoly...

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François Levrier @francoislevrier.bsky.social · 22/09/2026

Otto Frisch died #OTD in 1979. An Austrian-born British physicist, he and his aunt Lise Meitner explained the process of nuclear fission observed by Hahn and Strassmann. He outlined the process for producing an atomic bomb. en.wikipedia.org/wiki/Otto_Ro...

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François Levrier @francoislevrier.bsky.social · 22/09/2026

Frederick Soddy died #OTD in 1956. With Rutherford, he showed that radioactivity is associated with the transmutation of chemical elements. He received the 1921 Nobel Prize in Chemistry for his work on isotopes. en.wikipedia.org/wiki/Frederi...

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François Levrier @francoislevrier.bsky.social · 22/09/2026

Michael Faraday was born #OTD in 1791. Arguably one of the most brilliant experimental physicists in history, his work on the relationship between magnetism, electricity, and light laid the path for Maxwell’s electromagnetic theory. en.wikipedia.org/wiki/Michael...

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François Levrier @francoislevrier.bsky.social · 21/09/2026

Heike Kamerlingh Onnes was born #OTD in 1853. He received the 1913 Nobel Prize for his investigations of matter at very low temperatures, leading to the first liquefaction of helium and the discovery of superconductivity. en.wikipedia.org/wiki/Heike_K...

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François Levrier @francoislevrier.bsky.social · 20/09/2026

Pierre Méchain died #OTD in 1804. A surveyor and astronomer, he measured the Dunkirk-Barcelona meridian arc leading to the definition of the metre, and discovered several nebulæ that ended up in Messier's catalogue. en.wikipedia.org/wiki/Pierre_...

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François Levrier @francoislevrier.bsky.social · 20/09/2026

James Dewar was born #OTD in 1842. A British physicist and chemist, he invented a vacuum flask with which he was able to produce large quantities of liquid oxygen, that he then showed to be attracted by magnets. en.wikipedia.org/wiki/James_D...

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François Levrier @francoislevrier.bsky.social · 19/09/2026

Ole Rømer died #OTD in 1710. He timed Io’s eclipses in Jupiter’s shadow from different points on the Earth’s orbit, allowing Huygens and others to determine a value of approximately 212000 km/s for the speed of light. en.wikipedia.org/wiki/Ole_R%C...

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François Levrier @francoislevrier.bsky.social · 19/09/2026

Masatoshi Koshiba was born #OTD in 1926. He received the 2002 Nobel prize in Physics for pioneering work in neutrino astronomy, solving the solar neutrino problem by detecting evidence of neutrino oscillation with S-Kamiokande. en.wikipedia.org/wiki/Masatos...

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François Levrier @francoislevrier.bsky.social · 18/09/2026

Hippolyte Fizeau died #OTD in 1896. Working together with L. Foucault, and then as his rival, he determined the speed of light in air to within five percent, improving on Rømer’s much earlier determination. en.wikipedia.org/wiki/Hippoly...

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François Levrier @francoislevrier.bsky.social · 18/09/2026

John Douglas Cockroft died #OTD in 1967. With E. Walton, he designed the « charge pump » that was used to perform the first artificial nuclear fission. After WWII, he went on to develop several civil nuclear power projects. en.wikipedia.org/wiki/John_Co...

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François Levrier @francoislevrier.bsky.social · 18/09/2026

Leonhard Euler died #OTD in 1783. One of the greatest mathematicians of all time, he developed analysis, number theory, and graph theory. In physics, he made contributions in optics, elasticity, and fluid mechanics. en.wikipedia.org/wiki/Leonhar...

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François Levrier @francoislevrier.bsky.social · 18/09/2026

Léon Foucault was born #OTD in 1819. The Foucault pendulum’s oscillation plane appears to rotate due to Earth’s own rotation. Foucault’s currents occur when a conducting material is subjected to a varying magnetic field. en.wikipedia.org/wiki/L%C3%A9...

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François Levrier @francoislevrier.bsky.social · 17/09/2026

Joseph Petzval died #OTD in 1891. A Hungarian mathematician and physicist, he made important contributions to geometrical optics. The Petzval lens design, which allowed snapshot photography for the first time, is still in use. en.wikipedia.org/wiki/Joseph_...

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François Levrier @francoislevrier.bsky.social · 16/09/2026

James Jeans died #OTD in 1946. Jeans’ criterion gives the maximum mass for a gas cloud to be stable under the effects of self-gravity and thermal pressure. It is a fundamental tool to approach problems in star formation. en.wikipedia.org/wiki/James_J...

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François Levrier @francoislevrier.bsky.social · 16/09/2026

Alexander Friedmann died #OTD in 1925. The Friedmann equations describe the expansion of an isotropic and homogeneous universe with positive, null, or negative curvature, based on Einstein’s field equations of gravitation. en.wikipedia.org/wiki/Alexand...

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François Levrier @francoislevrier.bsky.social · 16/09/2026

Daniel Gabriel Fahrenheit died #OTD in 1736. He was a pioneer of thermometry, inventing the mercury-in-glass thermometer and devising the first standardized temperature scale, mostly still in use in the USA. en.wikipedia.org/wiki/Daniel_...

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François Levrier @francoislevrier.bsky.social · 15/09/2026

Joseph Plateau died #OTD in 1883. A Belgian physicist and mathematician, he worked in optics, inventing an early stroboscopic device, and surface tension problems. Plateau’s laws describe the structure of soap films. en.wikipedia.org/wiki/Joseph_...

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François Levrier @francoislevrier.bsky.social · 15/09/2026

Oskar Klein was born #OTD in 1894. He proposed that the fifth dimension introduced by Kaluza to generalize Einstein’s GR theory may be « curled up » and microscopic, an idea central to the development of string theory. en.wikipedia.org/wiki/Oskar_K...

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François Levrier @francoislevrier.bsky.social · 14/09/2026

Pierre Duhem died #OTD in 1916. A French theoretical physicist, philosopher and historian of science, he is best remembered for his works on chemical thermodynamics, including the Gibbs-Duhem and Duhem-Margules relations. en.wikipedia.org/wiki/Pierre_...

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François Levrier @francoislevrier.bsky.social · 14/09/2026

Jean-Dominique Cassini died #OTD in 1712, the first of a long lineage of astronomers of the Paris Observatory. Among many contributions, he discovered four satellites of Saturn and the ring division that bears his name. en.wikipedia.org/wiki/Giovann...

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François Levrier @francoislevrier.bsky.social · 12/09/2026

Sarah Frances Whiting died #OTD in 1927. An American physicist and astronomer, she set up one of the first undergraduate physics labs in the USA, at Wellesley College, and was the first director of Whitin Observatory. en.wikipedia.org/wiki/Sarah_F...

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François Levrier @francoislevrier.bsky.social · 12/09/2026

Irène Joliot-Curie was born #OTD in 1897. She received the 1935 Nobel Prize in Chemistry, together with her husband Frédéric, for their discovery of artificial radioactivity, opening the path to harnessing atomic power. en.wikipedia.org/wiki/Ir%C3%A...

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François Levrier @francoislevrier.bsky.social · 11/09/2026

James Jeans was born #OTD in 1877. Jeans’ criterion gives the maximum mass for a gas cloud to be stable under the effects of self-gravity and thermal pressure. It is a fundamental tool to approach problems in star formation. en.wikipedia.org/wiki/James_J...

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François Levrier @francoislevrier.bsky.social · 10/09/2026

Émilie du Châtelet died #OTD in 1749. She translated Newton’s « Principia » in French and contributed to the diffusion of Leibniz’s ideas in France. She is considered the first woman scientist in France. en.wikipedia.org/wiki/%C3%89m...

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François Levrier @francoislevrier.bsky.social · 10/09/2026

Hermann Bondi died #OTD in 2005. An Austrian-British cosmologist, he defended the steady-sate model with F. Hoyle and T. Gold. He also explained the nature of gravitational waves and worked on accretion onto compact objects. en.wikipedia.org/wiki/Hermann...

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François Levrier @francoislevrier.bsky.social · 10/09/2026

Felix Bloch died #OTD in 1983. He worked on ferromagnetism, the properties of electrons in solids, and nuclear magnetic induction, for which he received the 1952 Nobel Prize. He was the first Director-General of CERN. en.wikipedia.org/wiki/Felix_B...

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François Levrier @francoislevrier.bsky.social · 10/09/2026

Arthur Compton was born #OTD in 1892. The Compton effect describes the scattering of a photon by a charged particle, usually an electron. Depending on who gains energy in the process, the effect is « direct » or « inverse ». en.wikipedia.org/wiki/Arthur_...

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François Levrier @francoislevrier.bsky.social · 09/09/2026

Hans Georg Dehmelt was born #OTD in 1922. He received the 1989 Nobel Prize in Physics for developing the Penning trap, able to store charged particles using an axial magnetic field and a quadrupolar electric field. en.wikipedia.org/wiki/Hans_Ge...

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François Levrier @francoislevrier.bsky.social · 08/09/2026

Hermann von Helmholtz died #OTD in 1894. A German physicist, physician, and philosopher, he made vast contributions to thermodynamics, fluid mechanics, and electrodynamics. Many results in these fields bear his name. en.wikipedia.org/wiki/Hermann...

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François Levrier @francoislevrier.bsky.social · 08/09/2026

Hideki Yukawa died #OTD in 1981. He was the first Japanese physicist to be awarded a Nobel prize, for his prediction of the pion, a particle consisting of a quark and an anti-quark that mediates the nuclear force between nucleons. en.wikipedia.org/wiki/Hideki_...

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François Levrier @francoislevrier.bsky.social · 07/09/2026

James Van Allen was born #OTD in 1914. A pioneer of the scientific exploration of space, he devised sounding rockets launched from balloons (« rockoons »), which led to the discovery of the radiation belts surrounding the Earth. en.wikipedia.org/wiki/James_V...

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François Levrier @francoislevrier.bsky.social · 06/09/2026

John Dalton was born #OTD in 1766. He introduced atomic theory into chemistry and published the first scientific paper on colour blindness. Dalton’s law states that the total pressure in a gas mixture is the sum of partial pressures. en.wikipedia.org/wiki/John_Da...

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François Levrier @francoislevrier.bsky.social · 05/09/2026

Richard C. Tolman died #OTD in 1948. The TOV equation describes the structure of a non-rotating spherical body in general relativity. It implies a maximum mass for neutron stars, estimated from GW observations of mergers. en.wikipedia.org/wiki/Richard...

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