Baryons are the builders of the universe’s structure, and the reason atoms—and everything made of them—exist.
Baryons belong to the hadron family, meaning they are composite particles made of quarks. More specifically, they are a type of hadron that consists of three quarks bound together by the strong nuclear force, mediated by gluons. The most famous baryons are the proton and neutron, which make up atomic nuclei and form the foundation of all matter. But they’re not alone—there’s a whole zoo of exotic baryons, like the Lambda (Λ), Sigma (Σ), Xi (Ξ), and Omega (Ω) baryons, which contain heavier quarks and are often found in high-energy particle collisions or inside neutron stars.
What makes baryons special is their quark composition. While protons and neutrons are built from “up” and “down” quarks (the lightest and most stable types), other baryons can include strange, charm, bottom, or even top quarks, making them much heavier and more unstable. These exotic baryons decay quickly into lighter particles, which is why we don’t see them in everyday life—but they play a huge role in particle physics experiments and extreme cosmic environments.
Baryons also follow a rule called the Pauli exclusion principle, which means no two identical baryons can occupy the same quantum state. This is why neutron stars, made almost entirely of neutrons, resist collapsing despite their immense gravity—quantum mechanics literally holds them up!
While baryons dominate the visible universe, there’s a mystery: most of the mass in the cosmos is not baryonic. Dark matter, whatever it is, doesn’t seem to be made of baryons at all. So while protons and neutrons form everything we see—planets, stars, and life itself—something else, something invisible, outweighs them in the grand cosmic balance.