François Levrier
@francoislevrier.bsky.social
Professeur d’astrophysique - ENS Paris - Responsable du Master AAIS - Coordinateur de l’action thématique PCMI (Physique et Chimie du Milieu Interstellaire)
(Photo ©A. Vergallo)
(Photo ©A. Vergallo)
Julius Robert von Mayer was born #OTD in 1814. He gave one of the first statements of the first law of thermodynamics, suggesting work and heat to be different forms of energy that can nonetheless be converted into one another.
en.wikipedia.org/wiki/Julius_...
en.wikipedia.org/wiki/Julius_...
November 25, 2025 at 5:31 AM
Julius Robert von Mayer was born #OTD in 1814. He gave one of the first statements of the first law of thermodynamics, suggesting work and heat to be different forms of energy that can nonetheless be converted into one another.
en.wikipedia.org/wiki/Julius_...
en.wikipedia.org/wiki/Julius_...
Simon van der Meer was born #OTD in 1925. A Dutch physicist, he was awarded the Nobel Prize in 1984 for the experimental discovery, using CERN’s SPS, of the W and Z bosons that mediate the weak interaction.
en.wikipedia.org/wiki/Simon_v...
en.wikipedia.org/wiki/Simon_v...
November 24, 2025 at 8:01 AM
Simon van der Meer was born #OTD in 1925. A Dutch physicist, he was awarded the Nobel Prize in 1984 for the experimental discovery, using CERN’s SPS, of the W and Z bosons that mediate the weak interaction.
en.wikipedia.org/wiki/Simon_v...
en.wikipedia.org/wiki/Simon_v...
Johannes van der Waals was born #OTD in 1837. The van der Waals forces are intermolecular interactions, while the equation of state explains the gas-liquid transition and the existence of metastable states.
en.wikipedia.org/wiki/Johanne...
en.wikipedia.org/wiki/Johanne...
November 23, 2025 at 10:24 AM
Johannes van der Waals was born #OTD in 1837. The van der Waals forces are intermolecular interactions, while the equation of state explains the gas-liquid transition and the existence of metastable states.
en.wikipedia.org/wiki/Johanne...
en.wikipedia.org/wiki/Johanne...
Louis Néel was born #OTD in 1904. His studies of magnetism, in particular antiferromagnetism and ferrimagnetism, earned him the 1970 Nobel Prize. After WWII, he led the development of the scientific activity in the Grenoble area.
en.wikipedia.org/wiki/Louis_N...
en.wikipedia.org/wiki/Louis_N...
November 22, 2025 at 8:30 AM
Louis Néel was born #OTD in 1904. His studies of magnetism, in particular antiferromagnetism and ferrimagnetism, earned him the 1970 Nobel Prize. After WWII, he led the development of the scientific activity in the Grenoble area.
en.wikipedia.org/wiki/Louis_N...
en.wikipedia.org/wiki/Louis_N...
Edwin Hubble was born #OTD in 1889. By observing Cepheids in Andromeda, he showed that many « nebulae » are actually external galaxies. The Hubble-Lemaître law between redshift and distance implies the expansion of the Universe.
en.wikipedia.org/wiki/Edwin_H...
en.wikipedia.org/wiki/Edwin_H...
November 20, 2025 at 6:17 AM
Edwin Hubble was born #OTD in 1889. By observing Cepheids in Andromeda, he showed that many « nebulae » are actually external galaxies. The Hubble-Lemaître law between redshift and distance implies the expansion of the Universe.
en.wikipedia.org/wiki/Edwin_H...
en.wikipedia.org/wiki/Edwin_H...
Eleanor Helin was born #OTD in 1932. She headed JPL’s Near-Earth Asteroid Tracking program, discovering over 900 minor solar system bodies (asteroids from the Apollo, Amor, and Trojan families, and several comets).
en.wikipedia.org/wiki/Eleanor...
en.wikipedia.org/wiki/Eleanor...
November 19, 2025 at 7:15 AM
Eleanor Helin was born #OTD in 1932. She headed JPL’s Near-Earth Asteroid Tracking program, discovering over 900 minor solar system bodies (asteroids from the Apollo, Amor, and Trojan families, and several comets).
en.wikipedia.org/wiki/Eleanor...
en.wikipedia.org/wiki/Eleanor...
Patrick Blackett was born #OTD in 1897. He showed that elements could be transmuted by bombarding them with alpha particles. He also studied cosmic rays using cloud chambers, and made contributions to paleomagnetism.
en.wikipedia.org/wiki/Patrick...
en.wikipedia.org/wiki/Patrick...
November 18, 2025 at 5:40 AM
Patrick Blackett was born #OTD in 1897. He showed that elements could be transmuted by bombarding them with alpha particles. He also studied cosmic rays using cloud chambers, and made contributions to paleomagnetism.
en.wikipedia.org/wiki/Patrick...
en.wikipedia.org/wiki/Patrick...
Jean le Rond d’Alembert was born #OTD in 1717. A French polymath, his research in physics is mostly associated with waves and fluid dynamics. He also authored many articles for Diderot’s « Encyclopédie ».
en.wikipedia.org/wiki/Jean_le...
en.wikipedia.org/wiki/Jean_le...
November 16, 2025 at 7:51 AM
Jean le Rond d’Alembert was born #OTD in 1717. A French polymath, his research in physics is mostly associated with waves and fluid dynamics. He also authored many articles for Diderot’s « Encyclopédie ».
en.wikipedia.org/wiki/Jean_le...
en.wikipedia.org/wiki/Jean_le...
William Herschel was born #OTD in 1738. Using large reflector telescopes of his own design, he discovered Uranus and many solar system bodies. He was also a pioneer of spectrophotometry, discovering infrared radiation.
en.wikipedia.org/wiki/William...
en.wikipedia.org/wiki/William...
November 15, 2025 at 5:44 AM
William Herschel was born #OTD in 1738. Using large reflector telescopes of his own design, he discovered Uranus and many solar system bodies. He was also a pioneer of spectrophotometry, discovering infrared radiation.
en.wikipedia.org/wiki/William...
en.wikipedia.org/wiki/William...
Demain samedi 15 novembre, à 15h, j’aurai le plaisir de parler de la vie et de la mort des étoiles à la médiathèque d’Arc-en-Barrois (Haute-Marne), à l’invitation de l’association « Arc Patrimoine & Culture ».
November 14, 2025 at 6:44 PM
Demain samedi 15 novembre, à 15h, j’aurai le plaisir de parler de la vie et de la mort des étoiles à la médiathèque d’Arc-en-Barrois (Haute-Marne), à l’invitation de l’association « Arc Patrimoine & Culture ».
John W. Strutt, Lord Rayleigh, was born #OTD in 1842. His many contributions, most notably in fluid mechanics, optics, and acoustics, are reflected in the large number of phenomena and laws that bear his name.
en.wikipedia.org/wiki/John_Wi...
en.wikipedia.org/wiki/John_Wi...
November 12, 2025 at 5:29 AM
John W. Strutt, Lord Rayleigh, was born #OTD in 1842. His many contributions, most notably in fluid mechanics, optics, and acoustics, are reflected in the large number of phenomena and laws that bear his name.
en.wikipedia.org/wiki/John_Wi...
en.wikipedia.org/wiki/John_Wi...
Mildred Spiewak Dresselhaus was born #OTD in 1930. During her extensive career at MIT, she dedicated a great part of her research to the properties of nanostructures (fullerenes and nanotubes), ushering in new technologies.
en.wikipedia.org/wiki/Mildred...
en.wikipedia.org/wiki/Mildred...
November 11, 2025 at 7:41 AM
Mildred Spiewak Dresselhaus was born #OTD in 1930. During her extensive career at MIT, she dedicated a great part of her research to the properties of nanostructures (fullerenes and nanotubes), ushering in new technologies.
en.wikipedia.org/wiki/Mildred...
en.wikipedia.org/wiki/Mildred...
Carl Sagan was born #OTD in 1934. A pioneer of exobiology, he assembled messages on the Pioneer and Voyager probes and was an early advocate for SETI. He was an outspoken science communicator, writing many books for the general public.
en.wikipedia.org/wiki/Carl_Sa...
en.wikipedia.org/wiki/Carl_Sa...
November 9, 2025 at 8:20 AM
Carl Sagan was born #OTD in 1934. A pioneer of exobiology, he assembled messages on the Pioneer and Voyager probes and was an early advocate for SETI. He was an outspoken science communicator, writing many books for the general public.
en.wikipedia.org/wiki/Carl_Sa...
en.wikipedia.org/wiki/Carl_Sa...
Johannes Rydberg was born #OTD in 1854. The Rydberg formula gives the wavelength of light for an electronic transition in hydrogen atoms. In a Rydberg state, one electron is highly excited, making the spectrum hydrogen-like.
en.wikipedia.org/wiki/Johanne...
en.wikipedia.org/wiki/Johanne...
November 8, 2025 at 7:27 AM
Johannes Rydberg was born #OTD in 1854. The Rydberg formula gives the wavelength of light for an electronic transition in hydrogen atoms. In a Rydberg state, one electron is highly excited, making the spectrum hydrogen-like.
en.wikipedia.org/wiki/Johanne...
en.wikipedia.org/wiki/Johanne...
Edmund Halley was born #OTD in 1656. The second Astronomer Royal, he catalogued the southern hemisphere and computed the periodicity of the comet that bears his name. He demonstrated that stars, far from fixed, undergo proper motions.
en.wikipedia.org/wiki/Edmond_...
en.wikipedia.org/wiki/Edmond_...
November 8, 2025 at 7:26 AM
Edmund Halley was born #OTD in 1656. The second Astronomer Royal, he catalogued the southern hemisphere and computed the periodicity of the comet that bears his name. He demonstrated that stars, far from fixed, undergo proper motions.
en.wikipedia.org/wiki/Edmond_...
en.wikipedia.org/wiki/Edmond_...
Marie Skłodowska-Curie was born #OTD in 1867. One of the most prominent scientists of her time, she pioneered studies of radioactivity, coining the term and discovering two new chemical elements, polonium and radium.
en.wikipedia.org/wiki/Marie_C...
en.wikipedia.org/wiki/Marie_C...
November 7, 2025 at 5:40 AM
Marie Skłodowska-Curie was born #OTD in 1867. One of the most prominent scientists of her time, she pioneered studies of radioactivity, coining the term and discovering two new chemical elements, polonium and radium.
en.wikipedia.org/wiki/Marie_C...
en.wikipedia.org/wiki/Marie_C...
Fred Lawrence Whipple was born #OTD in 1906. He discovered several comets, hypothesizing that their composition was that of an icy conglomerate. He also designed a device to protect spacecraft from the impact of small particles.
en.wikipedia.org/wiki/Fred_La...
en.wikipedia.org/wiki/Fred_La...
November 5, 2025 at 6:38 AM
Fred Lawrence Whipple was born #OTD in 1906. He discovered several comets, hypothesizing that their composition was that of an icy conglomerate. He also designed a device to protect spacecraft from the impact of small particles.
en.wikipedia.org/wiki/Fred_La...
en.wikipedia.org/wiki/Fred_La...
Charles K. Kao was born #OTD in 1933. 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...
en.wikipedia.org/wiki/Charles...
November 4, 2025 at 5:40 AM
Charles K. Kao was born #OTD in 1933. 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...
en.wikipedia.org/wiki/Charles...
Alfred Perot was born #OTD in 1863. Together with C. Fabry, he invented a new high-precision, N-wave interferometer made of two semi-reflective plates. The Fabry-Perot interferometer had many applications in spectroscopy.
en.wikipedia.org/wiki/Alfred_...
en.wikipedia.org/wiki/Alfred_...
November 3, 2025 at 6:21 AM
Alfred Perot was born #OTD in 1863. Together with C. Fabry, he invented a new high-precision, N-wave interferometer made of two semi-reflective plates. The Fabry-Perot interferometer had many applications in spectroscopy.
en.wikipedia.org/wiki/Alfred_...
en.wikipedia.org/wiki/Alfred_...
Harlow Shapley was born #OTD in 1885. Initially opposed to Hubble’s idea that « spiral nebulæ » were galaxies like our own, rather than Galactic objects, he later defended the idea that they are organized in superclusters.
en.wikipedia.org/wiki/Harlow_...
en.wikipedia.org/wiki/Harlow_...
November 2, 2025 at 3:25 PM
Harlow Shapley was born #OTD in 1885. Initially opposed to Hubble’s idea that « spiral nebulæ » were galaxies like our own, rather than Galactic objects, he later defended the idea that they are organized in superclusters.
en.wikipedia.org/wiki/Harlow_...
en.wikipedia.org/wiki/Harlow_...
Hermann Bondi was born #OTD in 1919. 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...
en.wikipedia.org/wiki/Hermann...
November 1, 2025 at 8:02 AM
Hermann Bondi was born #OTD in 1919. 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...
en.wikipedia.org/wiki/Hermann...
Galileo Ferraris was born #OTD in 1847. An Italian physicist and electrical engineer, he worked on induction processes, building one of the first polyphase alternators, although he never patented his work, unlike N. Tesla.
en.wikipedia.org/wiki/Galileo...
en.wikipedia.org/wiki/Galileo...
October 31, 2025 at 6:50 AM
Galileo Ferraris was born #OTD in 1847. An Italian physicist and electrical engineer, he worked on induction processes, building one of the first polyphase alternators, although he never patented his work, unlike N. Tesla.
en.wikipedia.org/wiki/Galileo...
en.wikipedia.org/wiki/Galileo...
Homi Bhabha was born #OTD in 1909. He computed the cross-section of electron-positron scattering and described how primary cosmic rays interact with the atmosphere to produce air showers. Post-WWII, he led the Indian nuclear program.
en.wikipedia.org/wiki/Homi_J....
en.wikipedia.org/wiki/Homi_J....
October 30, 2025 at 7:18 AM
Homi Bhabha was born #OTD in 1909. He computed the cross-section of electron-positron scattering and described how primary cosmic rays interact with the atmosphere to produce air showers. Post-WWII, he led the Indian nuclear program.
en.wikipedia.org/wiki/Homi_J....
en.wikipedia.org/wiki/Homi_J....
Laura Bassi was born #OTD in 1711. She popularized Newtonian mechanics in Italy. She was one of the first women to earn a PhD and the first to become a teacher at the University of Bologna.
en.wikipedia.org/wiki/Laura_B...
en.wikipedia.org/wiki/Laura_B...
October 29, 2025 at 6:38 AM
Laura Bassi was born #OTD in 1711. She popularized Newtonian mechanics in Italy. She was one of the first women to earn a PhD and the first to become a teacher at the University of Bologna.
en.wikipedia.org/wiki/Laura_B...
en.wikipedia.org/wiki/Laura_B...
Wilhelm Anderson was born #OTD in 1880. A Russian-Estonian astrophysicist, he worked on the mass limit of white dwarf stars, providing a value that is slightly overestimated because of an invalid uniform-density hypothesis.
en.wikipedia.org/wiki/Wilhelm...
en.wikipedia.org/wiki/Wilhelm...
October 28, 2025 at 6:21 AM
Wilhelm Anderson was born #OTD in 1880. A Russian-Estonian astrophysicist, he worked on the mass limit of white dwarf stars, providing a value that is slightly overestimated because of an invalid uniform-density hypothesis.
en.wikipedia.org/wiki/Wilhelm...
en.wikipedia.org/wiki/Wilhelm...