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Physics

Wave-Particle Duality in Photons

Quick fact

In the double-slit experiment, photons fired one at a time still build an interference pattern over time—but placing a detector at the slits instantly destroys the pattern, revealing particle-like behavior. This is the central mystery of wave-particle duality.

Why this is interesting

You’ve seen light as a continuous wave—but did you know that a single photon can also act like a tiny bullet, striking just one point on a detector, while still creating an interference pattern as if it passed through two slits at once?