The astronomer and cosmologist Karim Benabed got killed on Wednesday in Paris. While cycling, run over by a truck-driver (with no further details at the moment). He was a senior research at IAP (Institut d’Astrophysique de Paris) and we actively collaborated together between 2005 and 2010 on an ANR project on efficient simulation methods for inferring cosmological parameters, based on PMC. And Bayesian model comparison. He was a very congenial person, very sharp in assimilating new methods and keen on exploring novel hypotheses. While we did not keep closely in touch, I would meet him now and then while visiting the IAP. Ironically, Darren Wraith, formerly a postdoc with him at IAP, was visiting me last week and we were reminiscing of that era as late as Saturday night over dinner… So sad (and also so absurd, a truck stopping the trajectory of someone managing to travel to the origins of the Universe). The above is a cartoon of him drawn during his cosmic microwave background presentation during the Nuit de l’Astronomie.
Archive for astronomy
Karim Benabed, astrophysician
Posted in Statistics, Travel, University life with tags ABC, adaptive importance sampling, ANR, astronomy, Bayesian inference, Bayesian model comparison, CMB, cosmology, cycling, dark energy, evidence, gravitational lensing, IAP, Institut d'Astrophysique de Paris, Nuit de l'Astronomie, Planck experiment, PMC, population Monte Carlo, traffic accident on December 5, 2025 by xi'anNature tidbits [21 Aug 2025]
Posted in Books, pictures, University life with tags @ScientistTrump, Antarctica, Arctic, astronomy, birth rates, black holes, climate change, COVID-19, electric car, Europe Union, global warming, ice sheet, mRNA, OpenAI, supernova, Trump administration, US research on October 16, 2025 by xi'anThe cover of this Nature issue is a fake!, being an artist’s rendering of a supernova (2021yfj) before it exploded, with the core exhibited as rich in silicon and sulfur. (The heaviest element in stars is iron, resulting from the fusion of the above. When the iron mass exceeds a limit, the star collapse into a neutron star or a black hole.)
On the Trump 2.0 administration’s attack-on-science front, an editorial exposes the irresponsibility of cancelling grants for mRNA studies (which Trump 1.0 supported during the COVID crisis). And a longer article points out the radical switch in managing federal grants, committees moving from scientists to political appointees, searching for “anti-American values”… And another one on the backlash following the report from said administration about climate change and global warming. (As blogged recently.)
At a more conceptual (and international) level, an article questions the usual stand on declining birth rates as being problematic. While acknowledging that public incentives have a highly variable mileage, the article remains vague on how supporting an ageing population while keeping an homogeneous welfare support will prove feasible. A second socio-economic article muses about the lack of a downward curve in the cost of electric cars, despite the drop in battery costs, pointing out the inefficiency of state support that creates profit bubbles for the manufacturers. Stricter policies on combustion vehicles similarly seem inefficient, given the violent reactions of car owners (as in the Gilets Jaunes revolt). The EU has alas recently backed down on its goal of prohibiting new combustion engines by 2035.
In shark contrast, a review paper document the rising probability of a climate catastrophe induced by the melting Antarctica, which could prove of a higher magnitude than the melting Arctic. (Even though the introduction article is rather confusing, mixing this issue with the pollution brought by Antarctic tourism and mentioning indigenous populations that do not exist on the 7th Continent).
And on the (weekly) AI front, the announcement of the downloadable gpt-oss from OpenAI, which I plan to check. And the debate on whether or not AI generated papers can plagiarise, again a poorly focussed article mostly missing the issues of the scientific worth of such papers (and the basic fact that they 100% plagiarise the literature dataset they learned from!).
Mars attack [live]
Posted in Kids, Mountains, pictures, Travel with tags astronomy, CNES, Mars, NASA, Perseverance, rover, spatial exploration on February 18, 2021 by xi'anblack holes capture Nobel
Posted in Statistics, Travel, University life with tags astronomy, Astrophysics, black holes, Garching, Max Planck Institute, Milky Way, Nobel Prize, relativity on October 7, 2020 by xi'an

