The Quantum Eraser: Can the Future Change the Past?

Send light through two slits and you get stripes. Tag which slit each photon used, and the stripes vanish, even if nobody reads the tag. Scramble the tag, and the stripes come back. Qubit walks through the quantum eraser, the mind-bending “delayed choice” version, and why it does NOT let anyone rewrite the past. Chapters: 0:00 Watch the path 0:05 The vanishing stripes 0:56 Waves and the double slit 1:53 Tagging the path 2:54 Quiz: scramble the labels 3:26 The quantum eraser 4:12 Delayed choice: did the future change the past? 5:39 Wheeler’s delayed choice 6:19 Why it matters: quantum computers 7:37 What we learned 8:09 End If you had a real eraser for information, what would you erase first? Tell us in the comments! Hashtags: #physics #quantumphysics #quantumeraser #doubleslit #science #thoughtexperiment #quantum #photons