PUBLIC LECTURE: The Hunt for Dark Matter

It is almost eighty years now since the original realisation that a majority of our universe consists of a type of matter that neither emits nor absorbs light. For this reason, we refer to it as "dark matter". Numerous astronomical observations have confirmed its existence, based on the gravitational pull that it exerts on luminous bodies (stars, galaxies, clusters of galaxies...). And yet we remain ignorant about the exact nature of this mysterious source of mass. Over the last thirty years our interest has concentrated on looking for new types of "dark" fundamental particles. These are hoped to interact every so often with dedicated detectors, but not too often, or their existence would have already been revealed in the laboratory. In a world-wide effort, numerous teams of researchers are looking for these particles, using highly sophisticated detectors. Most of these experiments take place deep underground, in mines or tunnels that provide a quiet environment able to reduce interference from known particles. We will discuss the many challenges faced by these dark matter hunters, and the progress made over the past few decades. Infused by a good dose of optimism, it can be claimed that the discovery of these new particles may be near.