{"id":1528,"date":"2024-01-10T19:50:41","date_gmt":"2024-01-10T19:50:41","guid":{"rendered":"https:\/\/live-optics-wp.pantheonsite.io\/oscoutreach\/?p=1528"},"modified":"2025-03-14T12:34:00","modified_gmt":"2025-03-14T19:34:00","slug":"penrose-room","status":"publish","type":"post","link":"https:\/\/wp.optics.arizona.edu\/oscoutreach\/penrose-room\/","title":{"rendered":"Penrose Unilluminable Room"},"content":{"rendered":"\r\n

Overview<\/strong>: A special room that was designed by Roger Penrose. A room with reflective walls where the shape of the room is such that no matter where a light source placed in the room there will always be at least one spot that the light does not touch.<\/p>\r\n\r\n\r\n\r\n

Supplies:<\/strong>\u00a0Penrose Unilluminable Room model, LED light source<\/p>\r\n\r\n\r\n\r\n

Objectives:<\/strong> Move the LED light source around the room to see if it is truly completely unilluminable<\/p>\r\n\r\n\r\n

\r\n\r\n\r\n

Setup:<\/strong><\/p>\r\n\r\n\r\n\r\n

    \r\n
  • Place the room model on the table<\/li>\r\n\r\n\r\n\r\n
  • Turn on the LED<\/li>\r\n<\/ul>\r\n\r\n\r\n\r\n

    How to run the demo:<\/strong><\/p>\r\n\r\n\r\n\r\n

      \r\n
    • Move the light source around the model to show that it is truly unilluminable<\/li>\r\n<\/ul>\r\n\r\n\r\n
      \r\n\r\n\r\n

      What\u2019s Happening?<\/strong><\/p>\r\n\r\n\r\n\r\n

      Roger Penrose’s design consists of two elliptical walls on the top and bottom and a rectangular area with two umbrella cutouts. The only requirements for the design to work are that the top and bottom walls are described as an ellipse and that the focal points of the ellipse coincide with the corner points of the umbrellas.<\/p>\r\n\r\n\r\n

      \r\n
      \"\"<\/figure>\r\n<\/div>\r\n\r\n\r\n

      How does it work? When you take into account the properties of an elliptical mirror (which we wont go into here), there are 3 things that happen with this room design. Refer to the diagram below.<\/p>\r\n\r\n\r\n\r\n

        \r\n
      • A light source placed inside\u00a0\u00a0will only illuminate\u00a0,\u00a0, and\u00a0\u00a0because it can never intersect the long axis of the ellipse between the focal points and enter the\u00a0\u00a0area.<\/li>\r\n\r\n\r\n\r\n
      • A light source placed in\u00a0\u00a0will leave\u00a0\u00a0and\u00a0\u00a0unilluminated because the light rays can only enter the lower half of the room between the two focal points of the lower ellipse. Thus, they can never intersect the long axis between the focal points and apexes and enter\u00a0\u00a0and\u00a0.<\/li>\r\n\r\n\r\n\r\n
      • A light source placed in\u00a0\u00a0will leave\u00a0,\u00a0,\u00a0, and\u00a0\u00a0unilluminated for the same reason<\/li>\r\n<\/ul>\r\n\r\n\r\n
        \r\n
        \"\"<\/figure>\r\n<\/div>\r\n\r\n
        \r\n\r\n\r\n

        Learn more:<\/strong>\u00a0(external links)<\/p>\r\n","protected":false},"excerpt":{"rendered":"","protected":false},"author":130,"featured_media":1669,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[2,8],"tags":[],"class_list":["post-1528","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-optical-illusion","category-physical-optics"],"_links":{"self":[{"href":"https:\/\/wp.optics.arizona.edu\/oscoutreach\/wp-json\/wp\/v2\/posts\/1528","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/wp.optics.arizona.edu\/oscoutreach\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/wp.optics.arizona.edu\/oscoutreach\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/wp.optics.arizona.edu\/oscoutreach\/wp-json\/wp\/v2\/users\/130"}],"replies":[{"embeddable":true,"href":"https:\/\/wp.optics.arizona.edu\/oscoutreach\/wp-json\/wp\/v2\/comments?post=1528"}],"version-history":[{"count":5,"href":"https:\/\/wp.optics.arizona.edu\/oscoutreach\/wp-json\/wp\/v2\/posts\/1528\/revisions"}],"predecessor-version":[{"id":1864,"href":"https:\/\/wp.optics.arizona.edu\/oscoutreach\/wp-json\/wp\/v2\/posts\/1528\/revisions\/1864"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/wp.optics.arizona.edu\/oscoutreach\/wp-json\/wp\/v2\/media\/1669"}],"wp:attachment":[{"href":"https:\/\/wp.optics.arizona.edu\/oscoutreach\/wp-json\/wp\/v2\/media?parent=1528"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/wp.optics.arizona.edu\/oscoutreach\/wp-json\/wp\/v2\/categories?post=1528"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/wp.optics.arizona.edu\/oscoutreach\/wp-json\/wp\/v2\/tags?post=1528"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}