Journées Scientifiques de l'Action Thématique GRAM

Session

Physique fondamentale

26 nov. 2026, 09:30

Amphi Pierre-Gilles de Gennes (Université Paris Cité)

6. Variation of Planck's quantum of action in Entangled Relativity and its impact on thermal radiation

Thomas Chehab (Observatoire de la côte d'Azur, Laboratoire ARTEMIS)

26/11/2026 09:30

Entangled Relativity is a non-linear reformulation of General Relativity that precludes the definition of a universe devoid of matter. In this framework, matter and spacetime are inseparably linked, in the literal sense that the gravitational dynamics cannot be defined independently of matter fields.

Despite its non-standard formulation, the phenomenology of General Relativity can be...

10. Probing spin-0 and spin-1 ultralight dark matter with binary pulsar timing

26/11/2026 10:00

Ultralight bosons are well-motivated dark-matter candidates that can behave as coherent oscillating fields on Galactic scales. At the lower end of the mass spectrum, these oscillations can remain coherent for decades and leave detectable signatures in high-precision astrophysical observations. Binary pulsars are particularly powerful probes of such effects.

We investigate quadratically...

13. Searching for short-range fifth-forces in space with MICROSCOPE and STEIN

Matthieu Dellavalle (ONERA - Office Nationale d'Études et de Recherches Aérospatiales)

26/11/2026 11:00

General Relativity (GR) is the best description of gravity so far. In 2018, the MICROSCOPE mission tested its cornerstone, the Equivalence Principle (EP), with unprecedented precision, setting the current state-of-the-art upper limit on its validity. Yet, keeping on testing gravity at better precision is of crucial interest in the quest of a model that could explain Dark Matter, Dark Energy or...

17. Probing Casimir-Polder and Fifth Forces with Nanograting Atom Interferometry.

26/11/2026 11:30

A fifth fundamental force (as a deviation from Newtonian gravity) is predicted by several theories addressing, for instance, questions relative to the dark sector or the lack of a unified framework for General Relativity and the Standard Model. Probing the existence of a fifth force at the submicron scale is challenging because electromagnetic interactions (e.g., the Casimir-Polder potential...

12. Fundamental physics and impact on astrophysics of Extended Theories of Electro-Magnetism (ETEM)

26/11/2026 12:00

Although compatible with General Relativity (GR), the dark Universe lacks experimental confirmation and support by the Standard Model (SM). Opposing darkness, extensions of GR face the successes of the latter. But photons, main messengers, are still read with the XIX Maxwell theory, although Quantum Electro-Dynamics (QED) requires non-linear corrections, e.g., photon-photon. Extended Theories...