Radioactivity is the spontaneous transformation of unstable atomic nuclei accompanied by the emission of ionizing radiation, typically in the form of alpha particles (helium-4 nuclei), beta particles (electrons or positrons), and gamma rays (high-energy photons), as well as neutrinos in many decay modes. It is governed by quantum-mechanical nuclear processes and characterized statistically by decay constants and half-lives, following first-order kinetics. Radioactivity alters nuclide identity through changes in proton and neutron numbers, driving nuclei toward more energetically favorable configurations. It is fundamental in nuclear physics, radiochemistry, dosimetry, and applications such as radiometric dating, nuclear medicine, radiation therapy, reactor physics, and radiation protection research.
Some historical events are so catastrophic they resist comprehension. And yet they compel us to try to understand them, again and again.
Environment
Apr 23, 2026
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Geopolitical tensions in Eastern Europe underscore the urgency of addressing the climate and radiological consequences of a regional nuclear conflict. Even a small-scale nuclear conflict at the Ukraine–Russia border could ...
Earth Sciences
Apr 23, 2026
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Too much stress can make even a rock crack. But before rocks reach their breaking point, they "sigh" a chemical warning by releasing nuclides, a type of atom defined by the number of neutrons as well as protons in the nucleus. ...
Earth Sciences
Apr 22, 2026
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When nuclear accidents happen, many people imagine radiation spreading everywhere and lasting forever. The reality is more complex. Radioactive materials move, change and sometimes disappear faster than people expect.
Environment
Apr 21, 2026
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In 1989, the Soviet nuclear-powered attack submarine Komsomolets sank to the bottom of the Norwegian Sea, along with its nuclear reactor and two nuclear warheads onboard. Komsomolets was constructed with a titanium alloy ...
Scientists have long relied on tree rings to learn about ancient solar storms—rare bursts of high-energy particles from the sun that can disrupt satellites, power grids, and communication systems across the planet. When these ...
Planetary Sciences
Jan 29, 2026
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More than a half century after the U.S. ignited 67 atomic weapons in the central Pacific Ocean, a former Navy base in the Bay Area continues to carry that nuclear legacy.
Environment
Nov 10, 2025
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A new study has uncovered how tiny differences in boron atoms can help scientists better predict the long-term behavior of glass used to store hazardous waste. The findings, published in Environmental and Biogeochemical Processes, ...
Earth Sciences
Oct 15, 2025
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A new study from the University of Missouri is helping veterinarians and pet owners better understand how to treat thyroid cancer in dogs by studying how to improve treatment with a type of therapy called radioactive iodine. ...
Veterinary medicine
Sep 9, 2025
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19
Radioactive decay is a fundamental process in nature by which an unstable atomic nucleus loses energy by radiation. Studying nuclear decay modes is crucial for understanding properties of atomic nuclei. In particular, exotic ...
General Physics
Jul 21, 2025
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