The double-slit experiment, interactive
Light is the strangest thing in physics. It arrives as discrete particles called photons that land at a single point. But while it travels, it behaves like a wave that ripples through space. This experiment lets you watch both happen at the same time. Fire one photon. Then a thousand. See what they paint together.
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Each amber dot leaving the source on the left is one photon: a single, indivisible quantum of light. It arrives at the detector screen as a single point. Particles do that. Waves don't.
The faint blue stripes in the middle region show the probability wave — what light "looks like" while it's passing through both slits at once. Bright stripes are where the two wave paths reinforce each other. Dark stripes are where they cancel out. That's pure wave behavior.
Here's the weird part: each photon is just one tiny dot, but where it lands is decided by the wave pattern. Fire one photon and the location seems random. Fire 2,000 and the dots pile up exactly into the stripes the wave predicts. Each photon, traveling alone, somehow already "knew" about both slits.
Nobody fully understands why. The math works perfectly. The intuition does not. That's wave-particle duality.
Made with Claude · Published on ArcadeLab