How to unravel early moments of the Universe with neutrinos: introduction to the PTOLEMY project

par Prof. Chris TULLY (Princeton University, USA)

jeudi 24 avr. 2025, 14:00 → 16:00 Europe/Paris

Amphitéatre (CPPM)

Abstract: What would we give to see an even younger image of the Universe from relics of the Big Bang?  And how can one even imagine how to do that?  One of the most subtle and important discoveries in elementary particle physics was to find that the tiny neutral particles that Enrico Fermi called the neutrinos have mass.  This mass was discovered indirectly through an effect predicted by Bruno Pontecorvo, now probed to high precision by KM3Net.  In the predictions of the youngest Universe, the tiny neutrino is immensely important, carrying nearly half of the total energy density of a rapidly expanding hot Big Bang, second only to the photons of light.  Unlike the photon, neutrinos are weakly interacting and can tell us about what happens inside burning stars, exploding stars, and even the early moments of the hot Big Bang.  PTOLEMY is a project that will one day detect the neutrinos from the Big Bang, but today, the focus is on first measuring the neutrino mass directly.  The talk describes how the original idea for direct measurement of the neutrino mass by Enrico Fermi has moved into the quantum sub-eV regime and how fantastic new technologies are opening our eyes to never before achieved sensitivity, bringing us closer to getting a glimpse of the very beginning.

About Chris Tully: Chris Tully earned his PhD in high-energy physics from Princeton University (*98) and his B.S. at Caltech (‘92).  He is a professor of physics at Princeton University and has served as associate chair of the physics department.  His research in particle physics spans three decades of energy-frontier particle colliders at Fermilab and CERN, and he was part of the team that discovered the Higgs boson at the LHC.  He was awarded NSF, CERN, Sloan and IBM-Einstein Fellowships.  He is the author of a popular textbook “Elementary Particle Physics in a Nutshell” and is a contributing author to “100 Years of Subatomic Physics.”