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We Were WRONG About the Quantum Eraser! ft. @LookingGlassUniverse​

2025-10-16 Education
414.7k
34.6k
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PBS Space Time
PBS Space Time
3.5m subscribers

Quantum Eraser Explained: Debunking Retrocausality with a Home Experiment.

Discover how an analogous home experiment clarifies the baffling results of the Delayed Choice Quantum Eraser, showing why future measurements do not truly impose retroactive influence on the past.

Short Summary

  • Resolve the paradox suggesting future choices influence past particle behavior.
  • Examine the mathematics of the standard delayed choice quantum eraser versus a simpler, polarization-based analog.
  • Understand that the apparent retrocausality is only revealed after post-processing and data sorting, not instantaneous collapse.
  • Learn that information flow is consistent regardless of the chosen frame of reference for observation.

This episode uses Mithuna Yoganathan's homemade setup to map the complex logic of the quantum eraser. The goal is to demonstrate mathematically equivalent outcomes, allowing viewers to see how careful data sorting—the "eraser" step—reconstructs either a single-slit or double-slit pattern based on how that information is correlated, resolving the illusion of backwards time influence.

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Description

Thank you to Cyber GhostVPN for Supporting PBS. Learn More About Cyber GhostVPN: https://cyberghostvpn.com/PBSSpaceTime Does quantum mechanics allow the future to retroactively influence the past, as in the infamous delayed choice quantum eraser experiment? How about we get an actual quantum physicist--who many of you already know--to show us how to do this experiment at home, and hopefully set this matter to rest. Check Out Looking Glass Universe: https://www.youtube.com/@LookingGlassUniverse And Check Out Matt’s Conversation with Mithuna https://youtu.be/QPuVtvIOYcM?si=TQovlQ6kW_6PPxKy Sign Up on Patreon to get access to the Space Time Discord! https://www.patreon.com/pbsspacetime Check out the Space Time Merch Store https://www.pbsspacetime.com/shop Sign up for the mailing list to get episode notifications and hear special announcements! https://mailchi.mp/1a6eb8f2717d/spacetime Search the Entire Space Time Library Here: https://search.pbsspacetime.com/ Hosted by Matt O'Dowd & Mithuna Yoganathan Written by Mithuna Yoganathan & Matt O'Dowd Post Production by Leonardo Scholzer Directed by Andrew Kornhaber Associate Producer: Bahar Gholipour Executive Producer: Andrew Kornhaber Executive in Charge for PBS: Maribel Lopez Director of Programming for PBS: Gabrielle Ewing Assistant Director of Programming for PBS: John Campbell Spacetime is a production of Kornhaber Brown for PBS Digital Studios. This program is produced by Kornhaber Brown, which is solely responsible for its content. © 2025 PBS. All rights reserved. End Credits Music by J.R.S. Schattenberg: https://www.youtube.com/user/MultiDroideka Space Time Was Made Possible In Part By: Big Bang Alexander Tamas David Paryente Juan Benet Mark Rosenthal Morgan Hough Peter Barrett Santiago Tj Steyn Vinnie Falco Supernova Ethan Cohen Glenn Sugden Grace Biaelcki Mark Heising Stephen Wilcox Tristan Lucian Claudius Aurelius Tyacke Hypernova Alex Kern Ben Delo Cal Stephens chuck zegar David Giltinan Dean Galvin Donal Botkin Gregory Forfa Jesse Cid Dyer John R. Slavik Justin Lloyd Kenneth See Massimiliano Pala Michael Tidwell Mike Purvis Paul Stehr-Green Scott Gorlick Scott Gray Spencer Jones Stephen Saslow Thomas Mouton Zachary Haberman Антон Кочков Daniel Muzquiz Gamma Ray Burst Aaron Pinto Adrien Molyneux Almog Cohen Anthony Leon Arko Provo Mukherjee Ayden Miller Ben McIntosh Bradley Jenkins Bradley Ulis Brandon Lattin Brian Cook Bryan White Chris Liao Christopher Wade Chuck Lukaszewski Collin Dutrow Craig Falls Craig Stonaha Dan Warren Daniel Donahue Daniel Jennings Daron Woods Darrell Stewart David Johnston Doyle Vann Eric Kiebler Eric Raschke Eric Schrenker Faraz Khan Frederic Simon Harsh Khandhadia Ian Williams Isaac Suttell James Trimmier Jeb Campbell Jeremy Soller Jerry Thomas jim bartosh John Anderson John De Witt John Funai John H. Austin, Jr. John591 Joseph Salomone Junaid Ali Kacper Cieśla Kane Holbrook Keith Pasko Kent Durham Koen Wilde Kyle Atkinson Marcelo Garcia Marion Lang Mark Daniel Cohen Mark Delagasse Matt Kaprocki Matthew Johnson Michael Barton Michael Clark Michael Lev Michael Purcell Nathaniel Bennett Nick Hoffenstoffer III Nicolas Katsantonis Paul Wood Rad Antonov Reuben Brewer Richard Steenbergen Robert DeChellis Ross Story Russell Moore SamSword Sandhya Devi Satwik Pani Sean Owen Shane Calimlim SilentGnome Sound Reason Steffen Bendel Steven Giallourakis Terje Vold Thomas Dougherty Tomaz Lovsin Tybie Fitzhugh Vlad Shipulin William Flinn WILLIAM HAY III Zac Sweers

Top Comments (10)

@blaziken_ssbm 2025-10-16

I sent myself through a double slit experiment and have now managed to both like and comment on this video simultaneously

1.5k 58 replies
@LookingGlassUniverse 2025-10-17

Thanks Matt for having me on the show! Working together was such a blast :)

1.3k 38 replies
@a_witcher94 2025-10-16

I like your funny words, magic man

766 14 replies
@Martan404 2025-10-16

I need more PBS Space Time. Please never stop making videos

386 20 replies
@kris6038 2025-10-17

The look on Mithuna's face when she got the interference pattern to work. I work in a lab, I know the science giddies when I see them lmao

275 5 replies
@pbsspacetime 2025-10-16

Thank you to Cyber GhostVPN for Supporting PBS. Learn More About Cyber GhostVPN: https://cyberghostvpn.com/PBSSpaceTime

211 24 replies
@jwesley235 2025-10-16

Out of all possible spacetimes in the multiverse, PBS Spacetime is my favorite.

162 1 replies
@sandro7 2025-10-26

“When you learn more about quantum mechanics, you don’t stop being confused, you just end up confused at a higher level”

95 1 replies
@stevenqirkle 2025-10-18

Just doing my part to feed the algo!

13
@GREFOUNDRY 2026-05-16

This is especially satisfying for RTRT frame as it predicts this.

0

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