Particle accelerator
A machine which accelerates tiny pieces of matter, i.e. particles, to bring them up to very high energies.

Antimatter
For every particle of matter, there is a particle of antimatter which is almost identical, except that it has an opposite electrical charge.

Atom
An atom is a component of matter. It is made up of a nucleus surrounded by a cloud of electrons. The nucleus is composed of protons and neutrons, themselves made up of three quarks each.

Big Bang
The phenomenon at the origin of our Universe, 13.7 billion years ago. We can think of it as an extremely dense and hot point which experienced a sudden and gigantic expansion.

Higgs boson
A particle which physicists are hunting for. Particles acquire their mass by the Brout-Englert-Higgs mechanism, as proven by the discovery of the Higgs boson.

Particle detector
Device used to measure the properties of the particles which pass through it. It is formed of different sub-detectors, each designed to record a specific property of the particles.

Fundamental forces
There are four forces in Nature. The most well-known is gravity, which revoles the Earth around the Sun and keeps us on the Earth. The force responsible for electrical and magnetic phenomena is the electromagnetic force. The other two forces, the strong force and the weak force, act on the nucleus of the atom.

Gluon
The particle which carries the strong force, one of the four fundamental forces. In protons and neutrons, gluons are what allow the quarks to remain stuck together.

Hadron
Family of particles comprising neutrons and protons, constituents of ordinary matter.

Ion
An atom with one or more electrons removed or added, so it has a net electrical charge.

Matter
For physicists, matter is what we and everything around us are made of: this passport, your eyes, but also the air you breathe, the Sun and the billions of galaxies in our Universe…

Standard Model
A theory which describes fundamental particles and four of the forces that act between them.

Neutrino
Neutral particle which only interacts very weakly with matter.

Particle
Elementary constituent of matter.

Quark
One of the fundamental particles of matter known today.