Lecture: “The Mystery of Dark Matter in the Universe”

Thursday, January 18, 2018, at 8:00 p.m.
Galileo Planetarium
By Julien Lavalle, a researcher at the CNRS and a theoretical physicist at the Montpellier Laboratory of Universe and Particles (LUPM).
Thanks to the remarkable advances in modern physics, both theoretically and observationally, it is now possible to have a coherent picture of the cosmos on nearly every scale, from the infinitely small to the infinitely large—that is, from the scale of elementary particles to that of the Universe as a whole. The precision of recent measurements in cosmology allows us to establish an energy balance for the Universe. In particular, it has been established that our universe is “flat,” that its expansion is accelerating, and that matter consists overwhelmingly (85%) of an unknown component that is invisible and interacts only gravitationally (or almost exclusively so) with the ordinary matter that characterizes our observable environment. The acceleration of expansion manifests as a repulsive force known as “dark energy,” while the unknown matter component has been given the equally unsettling nickname of “dark matter.”
Do these strange words mean that the sky is about to fall on our heads? Is the Star Wars about to begin? Of course not! They simply tell us that most of the universe still eludes our understanding—at least for now…
During this lecture, Julien Lavalle will focus on the topic of dark matter, seeking to demonstrate how it influences all macroscopic scales of the Universe—from the scale of galaxies to the scale of the cosmos—and how it proves to be indispensable to our understanding of galaxy formation.
He will explain how this cosmological and astrophysical puzzle may be solved by the physics of the infinitesimally small (in the form of new elementary particles), what theoretical avenues are currently being explored, and how the signatures of these hypothetical particles are being sought both directly and indirectly, using telescopes as well as particle accelerators.
The observational evidence is gradually narrowing in on the most promising theoretical solutions, thanks to a multitude of complementary international experiments in this field, and many of these solutions will either be confirmed or ruled out in the coming decades.
This lecture will begin with a screening of the film “Ghost of the Universe: The Hunt for Dark Matter” on the Planetarium’s dome.
Free admission with advance reservation by email by providing your first name, last name, email address, and phone number.
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