Why Quantum Information is Never Destroyed
May 23, 2018
710,475
17,263
1,715
2.67%
Search the Record
IndexedEvery word spoken in this episode is indexed. Type any phrase to jump straight to the moment it was said.
Type any word or phrase that may have been spoken. Click a result to seek the player to that exact moment.
Try a name, a topic, or a quoted line
Pbs Space Time Episodes Around May 23, 2018
See what was published immediately before and after this episode.
13:43Now PlayingWhy Quantum Information is Never Destroyed
Segments
YouTube Description
as posted by the channelViewers like you help make PBS (Thank you 😃) . Support your local PBS Member Station here
If you have perfect knowledge of every single particle in the universe, can you use the laws of physics to rewind all the way back to the Big Bang? Is the entire history of the universe perfectly knowable? Or has information somehow lost along the way?
You can further support us on Patreon at
Get your own Space Time tshirt at
Tweet at us! @pbsspacetime
Facebook: facebook.com/pbsspacetime
Email us! pbsspacetime [at] gmail [dot] com
Comment on Reddit
Help translate our videos!
Previous Episode:
Noether's Theorem and The Symmetries of Reality
The laws of physics are equations of motion. They are mathematical rules that dictate how systems evolve in time. Newton’s equations for classical mechanics, Maxwell’s equations for electromagnetism, and the Schrodinger equation for quantum mechanics. These laws can be used to predict how the universe will evolve into the future. They are deterministic; perfect knowledge of a system in the present perfectly predicts how the system will change in the next instant, and the instant after that, ad infinitum. But determinism in the forward-time direction does NOT guarantee that the same laws can perfectly predict the past. And yet this sort of deterministic symmetry - time-reversal symmetry - is essential for information itself to be conserved. Today we learn why conservation of information is such a fundamental requirement of quantum mechanics. In a future episode we’ll see how this law might be broken by black holes.
Here's that fun proof that independent quantum states can't evolve into the same quantum state while preserving unitarity! Apologies for the unavoidable technical notation, but a quick college course in introductory quantum mechanics will get you up to speed in no time :-P
Hosted by Matt O'Dowd
Written by Graeme Gossel and Matt O'Dowd
Graphics by Grayson Blackmon
Assistant Editing and Sound Design by Mike Petrow and Linda Huang
Made by Kornhaber Brown (www.kornhaberbrown.com)
Special thanks to our Patreon Big Bang, Quasar and Hypernova Supporters:
Big Bang
CoolAsCats
David Nicklas
Anton Lifshits
Joey Redner
Fabrice Eap
Quasar
Tambe Barsbay
Mayank M. Mehrota
Mars Yentur
Mark Rosenthal
Dean Fuqua
Roman Pinchuk
ColeslawPurdie
Hypernova
Edmund Fokschaner
Matthew O’Connor
Eugene Lawson
Barry Hatfield
Martha Hunt
Joseph Salomone
Chuck Zegar
Craig Peterson
Jordan Young
Ratfeast
John Hofmann
Thanks to our Patreon Gamma Ray Burst Supporters:
James Hughes
Fabian Olesen
Kris Fernet
Jane Meyers
James Flowers
Greg Allen
Denys Ivanov
Nick Virtue
Alexey Eromenko
Nicholas Rose
Scott Gossett
Mark Vasile
Patrick Murray
Sultan Alkhulaifi
Alex Seto
Michal-Peanut Karmi
Erik Stein
Kevin Warne
JJ Bagnell
Avi Goldfinger
John Pettit
Florian Stinglmayr
Benoit Pagé-Guitard
Nathan Leniz
Brandon Labonte
David Crane
Greg Weiss
Shannan Catalano
Brandon Cook
Guests & Subjects Covered
Sentinel Indexing in Progress
Metadata and chapters are available. Claim extraction for this episode is pending.
All video content is delivered via YouTube embedded players in accordance with the YouTube Terms of Service. Sentinel provides research tools that promote discovery and accountability across political media.