{"id":71130,"date":"2020-05-30T06:10:22","date_gmt":"2020-05-30T10:10:22","guid":{"rendered":"http:\/\/wavechronicle.com\/wave\/?p=71130"},"modified":"2020-05-02T15:05:05","modified_gmt":"2020-05-02T19:05:05","slug":"how-black-holes-spin-space-time","status":"publish","type":"post","link":"http:\/\/wavechronicle.com\/wave\/?p=71130","title":{"rendered":"How Black Holes Spin Space Time"},"content":{"rendered":"<p>If there\u2019s one thing cooler than a black hole it\u2019s a rotating black hole. Why? Because we can use them as futuristic power generators, galactic-scale bombs, and portals to other universes.<\/p>\n<p><iframe loading=\"lazy\" src=\"https:\/\/www.youtube.com\/embed\/UjgGdGzDFiM\" width=\"560\" height=\"315\" frameborder=\"0\" allowfullscreen=\"allowfullscreen\"><\/iframe><\/p>\n<p>Black holes are self-sustaining holes in the fabric of spacetime. Space at the event horizon cascades downwards, dragging more space behind it, sort of like how water drags itself near the edge of a waterfall. In a Kerr black hole, space above the event horizon is dragged around in a circle &#8211; so less waterfall and more whirlpool. Water spiralling down a drain in a flat sink doesn\u2019t know about the hole &#8211; it only knows about the motion of the water around it. In fact, it\u2019s possible to construct a black hole in general relativity rotating or otherwise &#8211; without any mass. Warp spacetime so it looks like the exterior of a black hole, and that warping will persist. So what is rotating? Spacetime is rotating.<\/p>\n<p><span class=\"style-scope yt-formatted-string\" dir=\"auto\">Sign Up on Patreon to get access to the Space Time Discord!<br \/>\n<\/span><a class=\"yt-simple-endpoint style-scope yt-formatted-string\" dir=\"auto\" spellcheck=\"false\" href=\"https:\/\/www.youtube.com\/redirect?q=https%3A%2F%2Fwww.patreon.com%2Fpbsspacetime&amp;redir_token=W_dALuTE4P9yZxU4zEAtn7jjJh18MTU4NzQwNjYyNkAxNTg3MzIwMjI2&amp;v=UjgGdGzDFiM&amp;event=video_description\" target=\"_blank\" rel=\"nofollow noopener\">https:\/\/www.patreon.com\/pbsspacetime<\/a><\/p>\n<p><span class=\"style-scope yt-formatted-string\" dir=\"auto\">Sign up for the mailing list to get episode notifications and hear special announcements!<br \/>\n<\/span><a class=\"yt-simple-endpoint style-scope yt-formatted-string\" dir=\"auto\" spellcheck=\"false\" href=\"https:\/\/www.youtube.com\/redirect?q=https%3A%2F%2Fmailchi.mp%2F1a6eb8f2717d%2Fspacetime&amp;redir_token=W_dALuTE4P9yZxU4zEAtn7jjJh18MTU4NzQwNjYyNkAxNTg3MzIwMjI2&amp;v=UjgGdGzDFiM&amp;event=video_description\" target=\"_blank\" rel=\"nofollow noopener\">https:\/\/mailchi.mp\/1a6eb8f2717d\/space&#8230;<\/a><\/p>\n<p><span class=\"style-scope yt-formatted-string\" dir=\"auto\">Check out the Space Time Merch Store<br \/>\n<\/span><a class=\"yt-simple-endpoint style-scope yt-formatted-string\" dir=\"auto\" spellcheck=\"false\" href=\"https:\/\/www.youtube.com\/redirect?q=https%3A%2F%2Fpbsspacetime.com%2F&amp;redir_token=W_dALuTE4P9yZxU4zEAtn7jjJh18MTU4NzQwNjYyNkAxNTg3MzIwMjI2&amp;v=UjgGdGzDFiM&amp;event=video_description\" target=\"_blank\" rel=\"nofollow noopener\">https:\/\/pbsspacetime.com\/<\/a><\/p>\n<div>\n<div id=\"0DE9E47C-871A-4F90-8440-B190C216800A_1\" class=\"mcafee_OK\" style=\"margin: 0px; padding: 0px; border: 0px; background: url('chrome-extension:\/\/fheoggkfdfchfphceeifdbepaooicaho\/images\/annotation\/green_icon.svg') center center \/ contain no-repeat transparent; height: 16px; width: 16px;\"><\/div>\n<\/div>\n<p>&nbsp;<\/p>\n","protected":false},"excerpt":{"rendered":"<p>If there\u2019s one thing cooler than a black hole it\u2019s a rotating black hole. Why? Because we can use them as futuristic power generators, galactic-scale bombs, and portals to other universes. Black holes are self-sustaining holes in the fabric of spacetime. Space at the event horizon cascades downwards, dragging more space behind it, sort of like how water drags itself near the edge of a waterfall. In a Kerr black hole, space above the event horizon is dragged around in a circle &#8211; so less waterfall and more whirlpool. Water spiralling down a drain in a flat sink doesn\u2019t know about the hole &#8211; it only knows about the motion of the water around it. In fact, it\u2019s possible to construct a black hole in general relativity rotating or otherwise &#8211; without any mass. Warp spacetime so it looks like the exterior of a black hole, and that warping will persist. So what is rotating? Spacetime is rotating. Sign Up on Patreon to get access to the Space Time Discord! https:\/\/www.patreon.com\/pbsspacetime Sign up for the mailing list to get episode notifications and hear special announcements! https:\/\/mailchi.mp\/1a6eb8f2717d\/space&#8230; Check out the Space Time Merch Store https:\/\/pbsspacetime.com\/ &nbsp;<\/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-71130","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\/71130","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=71130"}],"version-history":[{"count":1,"href":"http:\/\/wavechronicle.com\/wave\/index.php?rest_route=\/wp\/v2\/posts\/71130\/revisions"}],"predecessor-version":[{"id":71131,"href":"http:\/\/wavechronicle.com\/wave\/index.php?rest_route=\/wp\/v2\/posts\/71130\/revisions\/71131"}],"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=71130"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"http:\/\/wavechronicle.com\/wave\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=71130"},{"taxonomy":"post_tag","embeddable":true,"href":"http:\/\/wavechronicle.com\/wave\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=71130"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}