The famous double-slit experiment that reveals wave-particle duality. Watch individual particles pass through two slits and gradually build up an interference pattern — proof that matter behaves as waves.
Wave interference: each slit acts as a wave source. Where crests meet crests (constructive) we see bright bands; where crests meet troughs (destructive) we see darkness.
Adjust slit width, separation and wavelength. Watch particles accumulate one by one to form the interference pattern.
Richard Feynman called the double-slit experiment "the only mystery of quantum mechanics". Even firing electrons one at a time, the interference pattern still forms — each electron interferes with itself.