Participants

Marc Lachièze-Rey


Biography

Marc Lachièze-Rey is an alumnus of the École normale supérieure (rue d’Ulm) and holds a doctorate in physics. He is currently Director of Research at the CNRS and works at the APC (Astroparticle and Cosmology) laboratory. He specializes in fundamental theoretical physics, and is interested in the relationship between this discipline and mathematics and philosophy. He has written numerous articles and books, including Au-delà de l’espace et du temps : la nouvelle physique (Le Pommier, 2008), Les avatars du vide (Le Pommier, 2005) De l’infini (with J.-P. Luminet, Dunod, 2005), Figures du Ciel (with J.- P. Luminet, Le Seuil / Bibliothèque nationale de France, Paris, 1998), Initiation à la cosmologie (4th edition, Dunod, 2004), Voyager dans le temps: la physique moderne et la temporalité, (Seuil Sciences Ouvertes 2013) and Einstein à la plage (Dunod, 2015).

Conference: What is time called?

We’re used to using time in everyday life, and in some simple physics problems. Yet modern physics (described by Einstein’s relativistic theories) clearly tells us that there can be no such thing in nature. For example, that clocks don’t measure time, but durations, two related but very different notions. Time is a reconstruction from durations, not the other way round; this reconstruction can only be accomplished approximately, and under certain conditions: these are the conditions that allow us to use the notion of time, albeit with limited precision.