Bananas Naturally Produce Tiny Amounts of Antimatter

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Bananas contain potassium, and a tiny fraction of that potassium is the naturally radioactive isotope potassium-40. Most potassium-40 decays follow other paths, but a very small portion produces positrons, which are the antimatter counterparts of electrons. That means an ordinary banana can emit a positron roughly once every 75 minutes, although the exact rate varies with the amount of potassium in the fruit. The quantity is extraordinarily small and poses no meaningful radiation hazard from eating a banana. The positron also does not hang around for long. After encountering an ordinary electron, it can annihilate with it, producing energy in the form of other particles. The surprising part is therefore not that bananas contain some exotic substance, but that everyday matter naturally undergoes nuclear processes capable of producing antimatter.