The Double-Slit Experiment: Proof of Wave-Particle Duality

The double-slit experiment is one of the most famous demonstrations in physics.
When light passes through two slits, it creates an interference pattern—proof of wave behavior.
But when detected as particles, light appears as individual photons hitting a screen.
Even firing one photon at a time still builds up the wave-like interference pattern.
Electrons, atoms, and even some molecules also show this wave-particle duality.
Observation changes the outcome—measuring which slit a particle goes through destroys the pattern.
The experiment reveals that quantum objects exist in superposition until measured.
It challenged classical physics, which assumed waves and particles were completely separate.
The setup continues to inspire quantum research and deeper questions about reality.
The double-slit experiment remains the clearest proof that the quantum world defies everyday logic.