Particle physics studies the fundamental constituents of matter and radiation, the forces that act between them, and the high-energy processes that reveal how nature works at the smallest scales.
From atoms to fundamental particles
Atoms contain electrons and nuclei; nuclei contain protons and neutrons; protons and neutrons are built from quarks. Electrons and quarks are currently treated as elementary in the Standard Model, meaning experiments have not revealed smaller components inside them.
Particle physics asks what these fundamental particles are, how they interact and whether the current framework is complete.
How physicists study tiny scales
High-energy particle accelerators collide particles or direct beams at targets. Higher energies allow experiments to probe shorter distance scales and can create heavy particles that existed naturally in the hot early universe. Large detectors measure the tracks, energies and decay products left behind.
Not all particle physics uses colliders. Experiments also study neutrinos, cosmic rays, rare radioactive decays, dark-matter candidates and precision properties of known particles.
The Standard Model
The Standard Model organizes quarks, leptons and force-carrying particles and describes the electromagnetic, weak and strong interactions. It has survived extremely precise tests and predicted particles later discovered experimentally.
It is not a final theory. Gravity is not incorporated in the same framework, and the model does not explain dark matter, the cosmic matter-antimatter imbalance or several other major observations.
Why particle physics matters
Fundamental research changes our understanding of the universe, but the experimental tools also drive technologies in magnets, sensors, radiation detection, computing and medical imaging. Particle physics is therefore both a search for basic laws and a demanding engineering discipline.
Facilities such as CERN’s Large Hadron Collider test the Standard Model and search for signs of physics beyond it.
