The Double-Slit Experiment
The double-slit experiment reveals wave-particle duality.
Waves, particles, and the act of looking
By Peter Teoh, Science Writer
The double-slit experiment shows light and matter behaving like waves when unobserved, and like particles when measured. It is a core mystery of quantum physics.
Explainer: Interference and measurement
Focus: When a beam passes through two slits, the waves interfere and create bright and dark bands. Single photons fired one by one still build the same pattern over time.
If you measure which slit each photon takes, the interference vanishes. The act of measurement changes the system, forcing a definite path instead of a superposition.
Summary of Key Ideas:
- Unobserved particles show interference like waves.
- Observation collapses the interference pattern.
- Quantum behavior depends on measurement setup.
Side Notes
- Even large molecules can show interference.
- Which-path detectors trade knowledge for interference.
Trending Sidebar
- Quantum eraser experiments.
- Single-photon interference demos.
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