{"id":70407,"date":"2018-06-09T06:10:06","date_gmt":"2018-06-09T10:10:06","guid":{"rendered":"http:\/\/wavechronicle.com\/wave\/?p=70407"},"modified":"2018-05-28T10:37:00","modified_gmt":"2018-05-28T14:37:00","slug":"why-quantum-information-is-never-destroyed","status":"publish","type":"post","link":"http:\/\/wavechronicle.com\/wave\/?p=70407","title":{"rendered":"Why Quantum Information is Never Destroyed"},"content":{"rendered":"<p>The laws of physics are equations of motion. They are mathematical rules that dictate how systems evolve in time. Newton\u2019s equations for classical mechanics, Maxwell\u2019s 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 &#8211; time-reversal symmetry &#8211; 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\u2019ll see how this law might be broken by black holes.<\/p>\n<p>Here&#8217;s that fun proof that independent quantum states can&#8217;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 \ud83d\ude1b<\/p>\n<p><iframe loading=\"lazy\" src=\"https:\/\/www.youtube.com\/embed\/HF-9Dy6iB_4\" width=\"560\" height=\"315\" frameborder=\"0\" allowfullscreen=\"allowfullscreen\"><\/iframe><\/p>\n<p><a class=\"yt-simple-endpoint style-scope yt-formatted-string\" spellcheck=\"false\" href=\"https:\/\/www.youtube.com\/redirect?event=video_description&amp;v=HF-9Dy6iB_4&amp;q=http%3A%2F%2Fbit.ly%2F2Lpm6sL&amp;redir_token=Z-se3TczQSipR9UYh_SSOqCh4lZ8MTUyNzYwMzcwOUAxNTI3NTE3MzA5\">http:\/\/bit.ly\/2Lpm6sL<\/a><\/p>\n<p>Hosted by Matt O&#8217;Dowd<br \/>\nWritten by Graeme Gossel and Matt O&#8217;Dowd<br \/>\nGraphics by Grayson Blackmon<br \/>\nAssistant Editing and Sound Design by Mike Petrow and Linda Huang<br \/>\nMade by Kornhaber Brown (www.kornhaberbrown.com)<\/p>\n<p>You can further support us on Patreon at <a class=\"yt-simple-endpoint style-scope yt-formatted-string\" spellcheck=\"false\" href=\"https:\/\/www.youtube.com\/redirect?event=video_description&amp;v=HF-9Dy6iB_4&amp;q=https%3A%2F%2Fwww.patreon.com%2Fpbsspacetime&amp;redir_token=Z-se3TczQSipR9UYh_SSOqCh4lZ8MTUyNzYwMzcwOUAxNTI3NTE3MzA5\">https:\/\/www.patreon.com\/pbsspacetime<\/a><\/p>\n<p>Get your own Space Time t\u00ad-shirt at <a class=\"yt-simple-endpoint style-scope yt-formatted-string\" spellcheck=\"false\" href=\"https:\/\/www.youtube.com\/redirect?event=video_description&amp;v=HF-9Dy6iB_4&amp;q=http%3A%2F%2Fbit.ly%2F1QlzoBi&amp;redir_token=Z-se3TczQSipR9UYh_SSOqCh4lZ8MTUyNzYwMzcwOUAxNTI3NTE3MzA5\">http:\/\/bit.ly\/1QlzoBi<\/a><\/p>\n<p>Tweet at us! @pbsspacetime<br \/>\nFacebook: facebook.com\/pbsspacetime<br \/>\nEmail us! pbsspacetime [at] gmail [dot] com<br \/>\nComment on Reddit: <a class=\"yt-simple-endpoint style-scope yt-formatted-string\" spellcheck=\"false\" href=\"https:\/\/www.youtube.com\/redirect?event=video_description&amp;v=HF-9Dy6iB_4&amp;q=http%3A%2F%2Fwww.reddit.com%2Fr%2Fpbsspacetime&amp;redir_token=Z-se3TczQSipR9UYh_SSOqCh4lZ8MTUyNzYwMzcwOUAxNTI3NTE3MzA5\">http:\/\/www.reddit.com\/r\/pbsspacetime<\/a><\/p>\n","protected":false},"excerpt":{"rendered":"<p>The laws of physics are equations of motion. They are mathematical rules that dictate how systems evolve in time. Newton\u2019s equations for classical mechanics, Maxwell\u2019s 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 &#8211; time-reversal symmetry &#8211; 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\u2019ll see how this law might be broken by black holes. Here&#8217;s that fun proof that independent quantum states can&#8217;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 \ud83d\ude1b http:\/\/bit.ly\/2Lpm6sL Hosted by Matt O&#8217;Dowd Written by Graeme Gossel and Matt O&#8217;Dowd Graphics by Grayson Blackmon Assistant Editing and Sound Design by Mike Petrow and Linda Huang Made by Kornhaber Brown (www.kornhaberbrown.com) You can further support us on Patreon at https:\/\/www.patreon.com\/pbsspacetime Get your own Space Time t\u00ad-shirt at http:\/\/bit.ly\/1QlzoBi Tweet at us! @pbsspacetime Facebook: facebook.com\/pbsspacetime Email us! pbsspacetime [at] gmail [dot] com Comment on Reddit: http:\/\/www.reddit.com\/r\/pbsspacetime<\/p>\n","protected":false},"author":6,"featured_media":9298,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[127],"tags":[97,551,853],"class_list":["post-70407","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-edu","tag-education","tag-education-saturday","tag-space-time"],"acf":[],"_links":{"self":[{"href":"http:\/\/wavechronicle.com\/wave\/index.php?rest_route=\/wp\/v2\/posts\/70407","targetHints":{"allow":["GET"]}}],"collection":[{"href":"http:\/\/wavechronicle.com\/wave\/index.php?rest_route=\/wp\/v2\/posts"}],"about":[{"href":"http:\/\/wavechronicle.com\/wave\/index.php?rest_route=\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"http:\/\/wavechronicle.com\/wave\/index.php?rest_route=\/wp\/v2\/users\/6"}],"replies":[{"embeddable":true,"href":"http:\/\/wavechronicle.com\/wave\/index.php?rest_route=%2Fwp%2Fv2%2Fcomments&post=70407"}],"version-history":[{"count":1,"href":"http:\/\/wavechronicle.com\/wave\/index.php?rest_route=\/wp\/v2\/posts\/70407\/revisions"}],"predecessor-version":[{"id":70408,"href":"http:\/\/wavechronicle.com\/wave\/index.php?rest_route=\/wp\/v2\/posts\/70407\/revisions\/70408"}],"wp:featuredmedia":[{"embeddable":true,"href":"http:\/\/wavechronicle.com\/wave\/index.php?rest_route=\/wp\/v2\/media\/9298"}],"wp:attachment":[{"href":"http:\/\/wavechronicle.com\/wave\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=70407"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"http:\/\/wavechronicle.com\/wave\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=70407"},{"taxonomy":"post_tag","embeddable":true,"href":"http:\/\/wavechronicle.com\/wave\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=70407"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}