November 4, 2024

Jean-Philippe Uzan

CNRS Professor, Paris Institute of Astrophysics

Time is a central dimension of our universe. Phenomena evolve – in other words, there is a clear demarcation between the past, present and future. The history of time and physics is a long one, full of twists and turns and unexpected discoveries. Astronomy, with the cycles of the Moon and the Earth’s diurnal rotation, provided the first measurements of long time, leading to the first definition of the second. The story of how a naval disaster shifted astronomical time towards quantum time, and the quest for ever more precise watches should also be told. The dials of our watches, however, retain the memory of the diurnal drift of the stars. To understand movement, it was also necessary to mathematise time to fit it into our equations. This led to the Newtonian and Einsteinian revolutions of special and general relativities. Along the way, many questions, both practical and theoretical, led to advances in all areas of physics. What is a watch? How was the first watch made, and what ensured that it always measured the same time? Can we be sure that all clocks measure the same time? How can a clock be used to measure gravitation and test general relativity? Today, atomic clocks are the most precise tools in physics, and the CIPM – International Committee of Weights and Measures is considering a new definition of the second.

November 5, 2024

Daniel Baumann

Chee-Chun Leung Professor, National Taiwan University Director, Leung Center for Cosmology and Particle Astrophysics Professor of Theoretical Cosmology, University of Amsterdam

Symmetry is everywhere. We find it in art, music and architecture – and in biology, chemistry and physics. Many objects in the world around us are symmetrical, and we associate such symmetry with beauty, order and simplicity. In modern physics, however, we are not only interested in the symmetry of objects, but also with the symmetries of the physical laws themselves. In my lecture, I will explain how these laws, at the most fundamental level, are governed by symmetries.

We will start by describing the hidden spacetime symmetry of Maxwell’s theory of electromagnetism, which famously led Einstein to develop his theory of relativity. We will explain that such symmetries are not consequences of the laws of dynamics, but are rather the core principles that define these laws. It is through this profound change of perspective that symmetries have been put at the heart of fundamental physics.

Next, we will discuss the internal symmetries of quantum fields, which underly the structure of the Standard Model of particle physics. We will describe how symmetry explains the difference between matter and forces, how the stability of matter follows from symmetries and how the nature of the fundamental forces is dictated by symmetries. We will also show how the Higgs field breaks the symmetry between the electromagnetic and weak nuclear forces and gives a mass to all elementary particles. Finally, we will explore how symmetries and symmetry breaking manifest themselves on a cosmic scale, by describing how symmetries shape the structure and evolution of our Universe.

November 6, 2024

Yasmine Amhis

Research director CNRS Laboratoire de Physique des 2 Infinis Irène Joliot Curie

Besides being an intriguing, philosophical and recurring theme in science-fiction films, what do we know about antimatter today? In particular, what does it tell us about the notion of time?

In this talk, we’ll take you back in time to the Big Bang, the creation of matter and antimatter.

Thanks to discrete symmetries, physics offers us a mathematical framework for linking and describing the differences between matter and antimatter.

We’d like to provide some insight into the question: “Why has antimatter disappeared from our Universe?” This then raises the question of how we can study what has disappeared.

CERN’s experiments enable us to make antimatter, allowing us to explore its properties and unravel its mysteries. We’ll choose examples from the myriads of experimental techniques to illustrate how scientists are tackling this topic.

November 7, 2024




Edmund Copeland




Professor of Physics, University of Nottingham, UK




The Universe you and I live in is large, old and expanding – in fact, it is accelerating. It is 13.8 billion years old, and the atoms and light we see all around us appear to make up no more than 5% of the overall energy budget. The remaining 95% seems to be hidden from direct sight: 25% is in the form of cold dark matter which has decided not to interact with light, but without which galaxies like our Milky Way would not have formed. The remaining 70% is an unknown form of energy known as dark energy and is driving this acceleration.




Given that we don’t know what dark matter or dark energy is, it is remarkable that the paradigm which describes our universe, based on Einstein’s General Theory of Relativity and Quantum Mechanics, seems to fit the data beautifully. We will have fun exploring your Universe. We will discuss the key moments in its evolution, including asking how it began (spoiler – we don’t know). We will ask what happened in the first fractions of a second when the Universe seems to have undergone an incredibly fast rate of expansion leading to the generation of tiny perturbations in matter, which eventually led to the structure we see on large scales. We will discuss when stars and galaxies appeared, when the Universe started accelerating, what is causing this acceleration and what is likely to happen to our Universe in the future. It is a wonderful time to be studying the Universe: new telescopes are probing its deepest parts, whilst accelerators are probing its smallest constituents. We will visit these developments. The exciting prospect is that through the physics of the early universe, these smallest and largest scales are closely connected.





November 8, 2024




Enrico Coen




Professor at the Department of Cell and Developmental Biology, John Innes Centre, Norwich, UK




Why do we see such exquisite symmetries in the living world: butterfly wings, orchid flowers, faces?  Does the answer lie in physics, biology, or the way we look at things?  To answer this question, we will delve into the origins of symmetry in plants.  We will journey through many scales, from collisions between molecular filaments in a cell, to the blooming of a flower; from processes that last seconds, to those that span billions of years.  We will see how seemingly chaotic behaviors at one level can lead to smooth, continuous behavior at another, and how symmetries can emerge at each level though endless repetition.  Symmetries arise through a marriage between physics and biology: through the regularity of physical laws in space and time combined with the economy of natural selection.  These symmetries point to an underlying simplicity in nature, a simplicity that also underlies the origins of our brains, through which we try to make sense of the world around us.  Symmetries lie within us as much as in what we see.  We cannot separate ourselves from nature, for we are woven into the same tapestry, yet the prevalence of symmetry tells us that the tapestry is imbued with a harmony that makes the world both beautiful and comprehensible to us.