Physics
Particle Physics
Quick fact
The most abundant particle in the universe is the photon, with about 400 million per cubic meter of space, yet it has no mass.
Why this is interesting
You are made of atoms, but what are atoms made of? And what holds them together? The answers lead us to a tiny, invisible world of particles that shaped the entire universe.
Read the full explanation
Understanding Particle Physics
Particle physics is the study of the fundamental building blocks of matter and the forces that govern their interactions. Imagine starting with an atom: it has a nucleus and electrons. The nucleus is made of protons and neutrons, and each proton or neutron is made of even smaller particles called quarks. Quarks, along with electrons and similar particles called leptons, are considered elementary—they cannot be broken down further. All the matter we see is made from a small handful of these particles. To explore them, scientists use powerful particle accelerators that smash particles together at high speeds, revealing new particles and forces. The current best theory explaining all known particles and their interactions (except gravity) is called the Standard Model of particle physics.
A deeper explanation
The Standard Model categorizes fundamental particles into two main groups: fermions (matter particles) and bosons (force carriers). Fermions include quarks and leptons. Quarks combine to form protons and neutrons, while leptons include electrons, muons, neutrinos, and their antiparticles. Bosons mediate the forces: the photon for electromagnetism, gluons for the strong force, W and Z bosons for the weak force. The Higgs boson, discovered in 2012, gives mass to other particles through the Higgs field. Particle physics also explores why matter dominates antimatter and searches for particles beyond the Standard Model, such as those that might explain dark matter. The field underpins our understanding of the early universe and drives technologies like particle therapy for cancer and advanced computing.