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)
Pinned
Colloque 2024 du Programme PCMI (Bordeaux, 28-31 octobre 2024) - YouTube
www.youtube.com
Keep up to date on the advances of the PCMI community towards understanding the physics and chemistry of the interstellar medium, with the presentations made at our 2024 conference, now online on Youtube.
www.youtube.com/playlist?lis...
www.youtube.com/playlist?lis...
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...
Reposted by François Levrier
#Publicité #Famille
Une fiction interactive jouée, captée et diffusée en direct sur Twitch, Youtube, Arte.tv mais aussi dans 25 salles de cinéma simultanément, c’est « Les Burgers Sanglants » et c’est ce vendredi 31 octobre à 19h.
Une fiction interactive jouée, captée et diffusée en direct sur Twitch, Youtube, Arte.tv mais aussi dans 25 salles de cinéma simultanément, c’est « Les Burgers Sanglants » et c’est ce vendredi 31 octobre à 19h.
October 27, 2025 at 10:14 PM
#Publicité #Famille
Une fiction interactive jouée, captée et diffusée en direct sur Twitch, Youtube, Arte.tv mais aussi dans 25 salles de cinéma simultanément, c’est « Les Burgers Sanglants » et c’est ce vendredi 31 octobre à 19h.
Une fiction interactive jouée, captée et diffusée en direct sur Twitch, Youtube, Arte.tv mais aussi dans 25 salles de cinéma simultanément, c’est « Les Burgers Sanglants » et c’est ce vendredi 31 octobre à 19h.
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...
#Publicité #Famille
Une fiction interactive jouée, captée et diffusée en direct sur Twitch, Youtube, Arte.tv mais aussi dans 25 salles de cinéma simultanément, c’est « Les Burgers Sanglants » et c’est ce vendredi 31 octobre à 19h.
Une fiction interactive jouée, captée et diffusée en direct sur Twitch, Youtube, Arte.tv mais aussi dans 25 salles de cinéma simultanément, c’est « Les Burgers Sanglants » et c’est ce vendredi 31 octobre à 19h.
October 27, 2025 at 10:14 PM
#Publicité #Famille
Une fiction interactive jouée, captée et diffusée en direct sur Twitch, Youtube, Arte.tv mais aussi dans 25 salles de cinéma simultanément, c’est « Les Burgers Sanglants » et c’est ce vendredi 31 octobre à 19h.
Une fiction interactive jouée, captée et diffusée en direct sur Twitch, Youtube, Arte.tv mais aussi dans 25 salles de cinéma simultanément, c’est « Les Burgers Sanglants » et c’est ce vendredi 31 octobre à 19h.
Henrietta Hill Swope was born #OTD in 1902. She worked with H. Shapley, then W. Baade, to study variable stars. Using the period-luminosity relation for Cepheids discovered by H. S. Leavitt, she determined the distance to M31.
en.wikipedia.org/wiki/Henriet...
en.wikipedia.org/wiki/Henriet...
October 26, 2025 at 6:21 AM
Henrietta Hill Swope was born #OTD in 1902. She worked with H. Shapley, then W. Baade, to study variable stars. Using the period-luminosity relation for Cepheids discovered by H. S. Leavitt, she determined the distance to M31.
en.wikipedia.org/wiki/Henriet...
en.wikipedia.org/wiki/Henriet...
Henry Norris Russell was born #OTD in 1877. An American astronomer who devised the HR diagram, paving the way for stellar evolution studies. With F. Saunders, he developed the L-S coupling scheme for spin-orbit interactions.
en.wikipedia.org/wiki/Henry_N...
en.wikipedia.org/wiki/Henry_N...
October 25, 2025 at 6:33 AM
Henry Norris Russell was born #OTD in 1877. An American astronomer who devised the HR diagram, paving the way for stellar evolution studies. With F. Saunders, he developed the L-S coupling scheme for spin-orbit interactions.
en.wikipedia.org/wiki/Henry_N...
en.wikipedia.org/wiki/Henry_N...
Pierre-Gilles de Gennes was born #OTD in 1932. A specialist of « soft-matter » physics, his work on the properties of polymers and liquid crystals, in particular their phase transitions, earned him the 1991 Nobel Prize.
en.wikipedia.org/wiki/Pierre-...
en.wikipedia.org/wiki/Pierre-...
October 24, 2025 at 6:36 AM
Pierre-Gilles de Gennes was born #OTD in 1932. A specialist of « soft-matter » physics, his work on the properties of polymers and liquid crystals, in particular their phase transitions, earned him the 1991 Nobel Prize.
en.wikipedia.org/wiki/Pierre-...
en.wikipedia.org/wiki/Pierre-...
Felix Bloch was born #OTD in 1905. 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...
en.wikipedia.org/wiki/Felix_B...
October 23, 2025 at 6:29 AM
Felix Bloch was born #OTD in 1905. 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...
en.wikipedia.org/wiki/Felix_B...
Ilya Frank was born #OTD in 1908. He was awarded the Nobel Prize in 1958. The Frank-Tamm formula gives the spectrum of Cherenkov radiation emitted, per unit length, by a charged particle as it moves faster than light in a material medium.
en.wikipedia.org/wiki/Ilya_Fr...
en.wikipedia.org/wiki/Ilya_Fr...
October 23, 2025 at 6:28 AM
Ilya Frank was born #OTD in 1908. He was awarded the Nobel Prize in 1958. The Frank-Tamm formula gives the spectrum of Cherenkov radiation emitted, per unit length, by a charged particle as it moves faster than light in a material medium.
en.wikipedia.org/wiki/Ilya_Fr...
en.wikipedia.org/wiki/Ilya_Fr...
Karl Guthe Jansky was born #OTD in 1905. A radio engineer with Bell Labs, he investigated sources of static that might interfere with communications, and thus discovered the radio emission from our Galaxy in August 1931.
en.wikipedia.org/wiki/Karl_Gu...
en.wikipedia.org/wiki/Karl_Gu...
October 22, 2025 at 6:56 AM
Karl Guthe Jansky was born #OTD in 1905. A radio engineer with Bell Labs, he investigated sources of static that might interfere with communications, and thus discovered the radio emission from our Galaxy in August 1931.
en.wikipedia.org/wiki/Karl_Gu...
en.wikipedia.org/wiki/Karl_Gu...
Ingrid van Houten-Groeneveld was born #OTD in 1921. Along with Tom Gehrels and Cornelis Johannes van Houten, she is credited with discovering several thousand asteroids in the Palomar-Leiden survey.
en.wikipedia.org/wiki/Ingrid_...
en.wikipedia.org/wiki/Ingrid_...
October 21, 2025 at 6:12 AM
Ingrid van Houten-Groeneveld was born #OTD in 1921. Along with Tom Gehrels and Cornelis Johannes van Houten, she is credited with discovering several thousand asteroids in the Palomar-Leiden survey.
en.wikipedia.org/wiki/Ingrid_...
en.wikipedia.org/wiki/Ingrid_...
James Chadwick was born #OTD in 1891. He was awarded the 1935 Nobel Prize in Physics for his discovery of the neutron, identified as the unknown radiation produced through the interaction of alpha particles with beryllium.
en.wikipedia.org/wiki/James_C...
en.wikipedia.org/wiki/James_C...
October 20, 2025 at 5:25 AM
James Chadwick was born #OTD in 1891. He was awarded the 1935 Nobel Prize in Physics for his discovery of the neutron, identified as the unknown radiation produced through the interaction of alpha particles with beryllium.
en.wikipedia.org/wiki/James_C...
en.wikipedia.org/wiki/James_C...
Marguerite Perey was born #OTD in 1909. She discovered francium, one of the rarest naturally-occurring elements, as a product of actinium’s alpha decay. She was the first woman elected to the French « Académie des Sciences ».
en.wikipedia.org/wiki/Marguer...
en.wikipedia.org/wiki/Marguer...
October 19, 2025 at 6:37 AM
Marguerite Perey was born #OTD in 1909. She discovered francium, one of the rarest naturally-occurring elements, as a product of actinium’s alpha decay. She was the first woman elected to the French « Académie des Sciences ».
en.wikipedia.org/wiki/Marguer...
en.wikipedia.org/wiki/Marguer...