Neutrons are the quiet powerhouses of the atomic world—neutral, unassuming, but absolutely essential. Along with protons, they make up atomic nuclei, forming the foundation of all matter. Unlike protons, which carry a positive charge, neutrons have no electric charge at all. This neutrality makes them special: they help hold atomic nuclei together by balancing the repulsive forces between positively charged protons, all thanks to the strong nuclear force (transmitted by gluons).
Inside an atom, neutrons are stable and can exist indefinitely, but the moment they’re on their own, the clock starts ticking. A free neutron lasts only about 15 minutes before decaying into a proton, an electron, and an antineutrino. This process—beta decay—is a key player in nuclear physics, responsible for everything from radioactive transformations to the nuclear reactions that power stars.
Despite their neutral nature, neutrons are far from passive. They are crucial in nuclear fission, where splitting an atomic nucleus releases a burst of energy and more neutrons, triggering chain reactions that power nuclear reactors and, in extreme cases, atomic bombs. Their ability to pass through matter without being deflected by electric fields also makes them invaluable in scientific research, from probing materials at the atomic level to revealing hidden structures in archaeology and medicine.
Neutrons may not carry a charge, but they carry the weight of the universe—holding atoms together, fueling the stars, and shaping the very structure of reality.