In 1999, a group of scientists led by Marlan Scully sent photons through two slits, behind which there was a prism that converted each outgoing photon into a pair of quantum-entangled photons and split them into two paths. The first path sent photons to the main detector. The second path sent photons to a complicated system of reflectors and detectors.
It turned out that if a photon from the second path reached detectors determining which slit it had flown through, then the primary detector would register its paired photon as a particle. But if the photon from the second path reached detectors that didn’t determine which slit it had flown out of, then the main detector would register its paired photon as a wave. Measuring one photon affect its twin, regardless of distance and time, as the secondary system of detectors registered photons after the main one had. It’s as if the future determined the past.
The 10 weirdest quantum physics facts
1. Wave function collapse
2. Heisenberg uncertainty principle
3. Meissner effect
5. Quantum tunneling
6. Quantum entanglement
7. Quantum Zeno effect
8. Delayed choice quantum eraser
9. Quantum superposition
10. Quantum Cheshire Cat
The Phase. Shattering the Illusion of Reality
by Michael Raduga