The standard model of cosmology, better known as the big bang theory, has been built up over the last hundred years. Modern cosmology was born in 1917, with its roots in Einstein's theory of general relativity. The model gradually integrated nuclear and atomic physics, then quantum mechanics, offering an ever finer description of the universe. This construction has been successfully confronted with a growing number of observations, enabling us to reconstruct the history and structuring of the universe. This talk will describe the assumptions underpinning this model, as well as the major stages in its development, in order to offer a summary of its status, open questions and weaknesses. It will offer a historical dimension on the creation of a scientific theory, and open a reflection on the limits between science and philosophy.

In November 1915, Albert Einstein presented his theory of general relativity. It came as a shock to the scientific community. Based on mathematics that was little-known at the time, this theory challenged all accepted concepts of space and time. Triumphant in 1919 after Eddington's observations, it was little used until the 1960s, when it was revived and finally found its two fields of application: cosmology and relativistic astrophysics. For its 100th birthday, the theory is quite vigorous, passing all experimental tests. This centenary was celebrated by the first detection of gravitational waves and proof of the existence of black holes, to which we'll return later. This presentation follows a historical thread and illustrates the difficulty of admitting the conceptual revolutions a theory may require. It illustrates the threads that researchers can exploit to build new theories.

This lecture will look at “scientific constructs”. What does “seeing” mean to a physicist or a mathematician? Defining reality is an inextricable question (especially if you're not a philosopher), often implicit in the scientific process. It reveals continents where common sense no longer holds sway. What world does physics speak of? And mathematics? How do these two disciplines combine to paint a picture of reality? This talk will reflect on our relationship with knowledge and the work required to compare the realities revealed by science with the manifest reality offered by our senses. It will put into perspective the architecture of the different disciplines of knowledge, and open up a reflection on emerging phenomena and the notion of causality.

The study of our local universe has led to the formulation of a highly efficient cosmological model, in line with all existing observations. However, this model raises some challenging questions. Why is there a large universe? Why does it contain large objects? What about the origin of the universe? Is our universe adjusted to allow the appearance of life? These questions are at the limit of what the big bang can explain, and require extrapolation and speculation. Among them, the idea that our universe is only the emerging part of a richer structure, the multiverse, is at the heart of heated debate. We will summarize the motivations and limitations of this hypothesis, and discuss its status. This lecture illustrates the importance of distinguishing between science and philosophy, and the need to explore theories of nature. Particular attention to the distinction between validated facts and ideas in debate and gestation will open up a debate on the nature of scientific knowledge.

No one can hear you screaming in space. So isn't it absurd to try and talk about the universe in music? The notion of harmony, however, transcends music and our understanding of the universe. The quest for harmony raises questions that go beyond pure science, such as: what is the relationship between the cosmos, music and mathematics, as discovered in ancient Greece? Can we hear the stars, the galaxies, the primordial universe? Does our understanding of the universe influence musical creation? These questions will take us on a cosmic stroll through the solar system, pulsars and the cosmic microwave background. This lecture explores the porosity between disciplines that are today considered distinct. It will illustrate that disciplinary divisions evolve over time, and that music has influenced the thinking of many great thinkers. It opens the way to a reflection on the links between the arts and sciences.

This is a two-part conference with director and actor Etienne Pommeret. Based on readings of texts by authors such as Stevenson, Borges, Blanqui, Goethe, Farmer and Fosse, we offer an invitation to understand our world. The choice of texts may vary, and the openings are semi-improvised to leave room for surprise and interaction with the audience. This moment of exchange between science and literature will open up horizons on our universe and the benevolence we have shown it since we first laid eyes on it. Comments will illustrate that scientific culture opens up new interpretations of literary texts, and that many authors have been inspired by the science of their time. Audiences can bring their own literary references.