1. Particle physics: the need for energy and large-scale instruments

The aim of particle physics is to study the ultimate structure of matter. It is therefore a physics of the infinitely small, and as such requires the use of high-performance microscopes. The principle of a microscope is to illuminate the object you wish to study with a beam of suitable nature and energy. In the case of a conventional optical microscope, the beam is made up of visible light with a wavelength λ of the order of a micrometer.

The resolving power of a microscope is directly proportional to λ. If we want to observe smaller and smaller objects, we need to reduce λ. However, a principle of quantum mechanics introduced by Louis de Broglie in 1924, known as "wave-corpuscle duality", postulates that every particle is associated with a wave, and vice versa. Thus, light can be considered either as a wave (in experiments involving its propagation), or as a collection...