What IS time?

Presentation Date: Wednesday, June 18, 2025
Location: Opening Keynote, Colloque 2025 "Le Temps", Institut Universitaire de France, Besançon, France

Time is one of our most familiar experiences — yet remains one of the deepest mysteries of the universe. As Augustine famously remarked, "If no one asks me, I know what it is. If I wish to explain it, I do not know." Across cultures, disciplines, and eras, time has been imagined as linear, cyclical, relative, and even illusory. It shapes our emotions, structures our lives, and defines our understanding of change and mortality.

In this keynote, we will explore the many facets of time — from its philosophical and psychological dimensions to its role in modern physics. We will then delve into humanity’s attempts to "capture time" by measuring and manipulating events at extraordinarily short timescales. Drawing on recent advances in ultrafast laser science, we will journey across a logarithmic scale from femtoseconds to the age of the universe, offering a new perspective on time and motion at the speed of light.