How a potassium atom makes a positron
Potassium is an essential mineral in the body, helping cells maintain the electrical balance they need to function. A tiny fraction of natural potassium is the radioactive isotope potassium-40. In one of its rare decay pathways, a potassium-40 nucleus changes into a different element and emits a positron—a particle with the same mass as an electron but the opposite electric charge.
The positron does not linger. It moves through nearby tissue, losing energy as it interacts with matter. Once it encounters an electron, their opposite charges allow the pair to annihilate: both particles disappear, and their energy emerges as gamma rays, a form of high-energy light.
A real event, not a health threat
This sequence happens at the scale of individual atoms. It does not mean the body stores a supply of antimatter, and it is not an explosion: each particle pair releases only a minuscule amount of energy. The positrons are produced and destroyed continually, while the body’s ordinary potassium remains part of normal biology.
That fleeting trail—from a naturally present atom to a particle that vanishes on contact—shows how radioactive decay can occur inside everyday matter without being something a person can feel.
