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Glossary

Quantum glossary

Uncertainty principle

Also: heisenberg

A limit on how sharply a state can define two incompatible quantities at once, such as position and momentum.

It is a property of the state, not a clumsiness of the measuring device: a narrow wave packet in position is necessarily a broad one in momentum, exactly as a short pulse needs many frequencies.

Δx · Δp ≥ ħ/2

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Related terms

  • Wavefunction — The function ψ(x) giving the amplitude for a particle to be found at each position.