00:00Laser beams fire straight into a silicon photon crystal right now.
00:04A photon registers on the back screen, recording a specific arrival point,
00:09while its prior path remains entangled and undefined.
00:13Common sense says the past is fixed,
00:15but quantum measurements can erase which way data after detection.
00:19Quantum entanglement scrambles the detection data,
00:22forcing nature to instantly wipe the particle tracking records completely clean.
00:27This quantum eraser setup shows that detection choices
00:30can seem to retroactively define a particle's history.
