The mystery that broke physics. For four hundred years the greatest minds in science have tried to answer one simple question: what is light? Isaac Newton said particles. Thomas Young proved waves. Albert Einstein brought particles back. And quantum mechanics revealed something stranger than either. Light is somehow both. And neither. And no one can explain why.
In eighteen oh one, Thomas Young performed an experiment so simple it changed physics forever. Sunlight through two slits. An interference pattern on a screen. Proof that light is a wave. Newton was wrong. A century later, Einstein studied the photoelectric effect and proved light comes in discrete packets called photons. Young was wrong. Both were right. The contradiction stands.
The double slit experiment reveals the deepest mystery. Fire single photons one at a time through two slits. Each arrives as a particle. Yet collectively they form a wave pattern. Each photon seems to go through both slits simultaneously. But try to observe which slit it passes through and the interference vanishes. The act of observation changes reality.
Credit to : The Calm Scientist
