strangeness

physics

Also known as: strange particle

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July 14, 2026

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In particle physics, "strangeness" refers to a quantum property assigned to certain subatomic particles, specifically those discovered in cosmic rays starting in 1947. These "strange" particles were heavier than pions but lighter than protons and exhibited unusual behavior: they were created in strong interactions but decayed much more slowly, as if a weaker force was at play.1

To explain this, physicists Murray Gell-Mann and Kazuhiko Nishijima independently proposed in 1953 that these particles possessed a new property called "strangeness," denoted by the quantum number S. This property is conserved in strong nuclear reactions but not in the weaker decay processes. This concept helped organize the growing number of observed subatomic particles and is a key aspect of understanding particle behavior within the framework of quantum mechanics.123

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subatomic particle
Strangeness
The discovery of the pion in 1947 seemed to restore order to the study of particle physics, but this order did not last long. Later in the year Clifford Butler and George Rochester, two British physicists studying cosmic rays, discovered the first examples of…
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The discovery of the pion in 1947 seemed to restore order to the study of particle physics, but this order did not last long. Later in the year Clifford Butler and George Rochester, two British physicists studying cosmic rays, discovered the first examples of…
Read More

hyperon
…they are often produced—were named strange particles. This behaviour has since been ascribed to the weak decays of the specific quarks—also called strange—that they contain.
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…they are often produced—were named strange particles. This behaviour has since been ascribed to the weak decays of the specific quarks—also called strange—that they contain.
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Murray Gell-Mann
…introduced the concept of “strangeness,” a quantum property that accounted for previously puzzling decay patterns of certain mesons. As defined by Gell-Mann, strangeness is conserved when any subatomic particle interacts via the strong force—i.e., the force that binds the components of the atomic nucleus. Gell-Mann joined the faculty of…
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…introduced the concept of “strangeness,” a quantum property that accounted for previously puzzling decay patterns of certain mesons. As defined by Gell-Mann, strangeness is conserved when any subatomic particle interacts via the strong force—i.e., the force that binds the components of the atomic nucleus. Gell-Mann joined the faculty of…
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