The million-fold energy hidden within the atomic nucleus

Science · Published 23 October 2026 Swipe more like this →

In short: Deep inside the atom, a tiny space holds immense power. The forces binding protons and neutrons are roughly one million times stronger than typical atomic energies, driving the massive energy releases seen in nuclear fission and fusion reactions.

Nuclear physics explores the structure of the nucleus, a region roughly 10,000 times smaller than the atom itself, spanning just a few femtometres (10⁻¹⁵ metres) across. Within this dense core, protons and neutrons are held together by the strong force. This interaction is mediated by the exchange of mesons between nucleons, a mechanism that provides the fundamental stability of the nucleus. Understanding these complex structures requires the application of quantum theory to model the behavior of these constituent particles.

The energy released during nuclear reactions, such as fission—where heavy nuclei split—and fusion—where nuclei merge—far exceeds the energy of any chemical reaction. These processes often involve the emission of radiation. Unstable nuclei may release gamma rays, which are energetic nuclear photons, or particles like alpha rays (helium nuclei) and beta rays (electrons and positrons). The latter is driven by the much weaker weak interaction, a process that can even involve a proton converting into a neutron. The process of beta decay is often accompanied by the presence of neutrinos. Furthermore, whenever the nuclear charge changes during these radioactive decays or collisions, the chemical identity of the target nucleus is fundamentally altered.

Modern research continues to push the boundaries of this field. Scientists are now developing ultraprecise nuclear clocks that use transitions in atomic nuclei to establish new time standards. Meanwhile, the study of high-energy physics, which emerged in the 1930s from cosmic-ray research, now utilizes massive particle accelerators. These 'meson factories' allow researchers to direct beams of particles against targets to analyze recoiling fragments, revealing the intricate details of nuclear structure and the fundamental forces of nature. While high-energy physics grew from studying extraterrestrial radiations in the atmosphere, researchers now use accelerators to study unstable particles. This field also encompasses the study of quarks and gluons, which are the fundamental building blocks of hadrons.

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