{"id":54,"date":"2007-02-06T16:04:33","date_gmt":"2007-02-06T21:04:33","guid":{"rendered":"http:\/\/www.thehistoricalarchive.com\/happenings\/a-brief-history-of-atomic-clocks\/"},"modified":"2007-02-06T16:04:33","modified_gmt":"2007-02-06T21:04:33","slug":"a-brief-history-of-atomic-clocks","status":"publish","type":"post","link":"http:\/\/www.thehistoricalarchive.com\/happenings\/54\/a-brief-history-of-atomic-clocks\/","title":{"rendered":"A Brief History of Atomic Clocks"},"content":{"rendered":"<div class=\"147322a129097e1fa44d6732c925fd6d\" data-index=\"1\" style=\"float: none; margin:10px 0 10px 0; text-align:center;\">\n<script type=\"text\/javascript\"><!--\r\ngoogle_ad_client = \"ca-pub-8134560547846945\";\r\n\/* 468x60 tha *\/\r\ngoogle_ad_slot = \"1487607395\";\r\ngoogle_ad_width = 468;\r\ngoogle_ad_height = 60;\r\n\/\/-->\r\n<\/script>\r\n<script type=\"text\/javascript\"\r\nsrc=\"http:\/\/pagead2.googlesyndication.com\/pagead\/show_ads.js\">\r\n<\/script>\n<\/div>\n<p><strong>1945 <\/strong>&#8212; Isidor Rabi, a physics professor at Columbia University, suggests a clock could be made from a technique he developed in the 1930&#8217;s called atomic beam magnetic resonance.<\/p>\n<p><strong>1949 <\/strong>&#8212; Using Rabi\u00e2\u20ac\u2122s technique, NIST (then the National Bureau of Standards) announces the world\u00e2\u20ac\u2122s first atomic clock using the ammonia molecule as the source of vibrations.<\/p>\n<p><strong>1952 <\/strong>&#8212; NIST completes the first accurate measurement of the frequency of the cesium clock resonance. The apparatus for this measurement is named NBS-1.<\/p>\n<p><center><img decoding=\"async\" alt=\"NBS-1 Cesium Clock\" src=\"http:\/\/tf.nist.gov\/general\/museum\/nbs-1.jpg\" \/><\/center><strong>1954 <\/strong>&#8212; NBS-1 is moved to NIST\u00e2\u20ac\u2122s new laboratories in Boulder, Colorado.<\/p>\n<p><strong>1955 <\/strong>&#8211;The National Physical Laboratory in England builds the first cesium-beam    clock used as a calibration source.<\/p>\n<p><strong>1958 <\/strong>&#8212; Commercial cesium clocks become available, costing $20,000 each.<\/p>\n<p><strong>1959 <\/strong>&#8212; NBS-1 goes into regular service as NIST&#8217;s primary frequency standard.<\/p>\n<p><strong>1960<\/strong> &#8212; NBS-2 is inaugurated in Boulder; it can run for long periods unattended     and is used to calibrate secondary standards.<\/p>\n<p><center><img decoding=\"async\" alt=\"NBS-2 Cesium Clock\" src=\"http:\/\/tf.nist.gov\/general\/museum\/nbs-2.jpg\" \/><\/center><strong>1963<\/strong> &#8212; The search for a clock with improved accuracy and stability results in NBS-3.<\/p>\n<p><center><img decoding=\"async\" alt=\"NBS-3 Cesium Clock\" src=\"http:\/\/tf.nist.gov\/general\/museum\/nbs-3.jpg\" \/><\/center><strong>1967<\/strong> &#8212; The 13th General Conference on Weights and Measures defines the second on the basis of vibrations of the cesium atom; the world\u00e2\u20ac\u2122s timekeeping system no longer has an astronomical basis.<\/p>\n<p><strong>1968 <\/strong>&#8212; NBS-4, the world\u00e2\u20ac\u2122s most stable cesium clock, is completed. This clock was used into the 1990s as part of the NIST time system.<\/p>\n<p><center><img decoding=\"async\" alt=\"NBS-4 Cesium Clock\" src=\"http:\/\/tf.nist.gov\/general\/museum\/nbs-4.jpg\" \/><\/center><strong>1972<\/strong> &#8212; NBS-5, an advanced cesium beam device, is completed and serves as the primary standard.<\/p>\n<p><center><img decoding=\"async\" alt=\"NBS-5 Cesium Clock\" src=\"http:\/\/tf.nist.gov\/general\/museum\/nbs-5.jpg\" \/><\/center><strong>1975<\/strong> &#8212; NBS-6 begins operation; an outgrowth of NBS-5, it is one of the world\u00e2\u20ac\u2122s most accurate atomic clocks, neither gaining nor losing one second in 300,000 years.<\/p>\n<p><center><img decoding=\"async\" alt=\"NBS-6 Cesium Clock\" src=\"http:\/\/tf.nist.gov\/general\/museum\/nbs-6.jpg\" \/><\/center><strong>1989<\/strong> &#8212; The Nobel Prize in Physics is awarded to three researchers &#8212; Norman Ramsey of Harvard University, Hans Dehmelt of the University of Washington and Wolfgang Paul of the University of Bonn &#8212; for their work in the development of atomic clocks. NIST\u00e2\u20ac\u2122s work is cited as advancing their earlier research.<\/p>\n<p><strong>1993 <\/strong>&#8212; NIST-7 comes on line; eventually, it achieves an uncertainty of 5 x 10<sup>-15<\/sup>, or 20 times more accurate than NBS-6.<\/p>\n<p><center><img decoding=\"async\" alt=\"NIST-7 Cesium Clock\" src=\"http:\/\/tf.nist.gov\/general\/museum\/nist-7a.jpg\" \/><\/center><strong>1999 <\/strong>&#8212; NIST-F1 begins operation with an uncertainty of 1.7 x 10<sup>-15<\/sup>, or accuracy to about one second in 20 million years, making it one of the most accurate clocks ever made (a distinction shared with similar standards in France and Germany).<\/p>\n<p><center><img decoding=\"async\" alt=\"NIST-F1 Cesium Clock\" src=\"http:\/\/tf.nist.gov\/general\/museum\/nist-f1.jpg\" \/><\/center><\/p>\n\n<div style=\"font-size: 0px; height: 0px; line-height: 0px; margin: 0; padding: 0; clear: both;\"><\/div><iframe src=\"http:\/\/www.facebook.com\/plugins\/like.php?href=http%3A%2F%2Fwww.thehistoricalarchive.com%2Fhappenings%2F54%2Fa-brief-history-of-atomic-clocks%2F&amp;layout=standard&amp;show_faces=true&amp;width=450&amp;action=like&amp;colorscheme=light\" scrolling=\"no\" frameborder=\"0\" allowTransparency=\"true\" style=\"border:none; overflow:hidden; width:450px;margin-top:5px;\"><\/iframe>","protected":false},"excerpt":{"rendered":"<p>1945 &#8212; Isidor Rabi, a physics professor at Columbia University, suggests a clock could be made from a technique he developed in the 1930&#8217;s called atomic beam magnetic resonance. 1949 &#8212; Using Rabi\u00e2\u20ac\u2122s technique, NIST (then the National Bureau of Standards) announces the world\u00e2\u20ac\u2122s first atomic clock using the ammonia molecule as the source of [&hellip;]<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"closed","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"_links_to":"","_links_to_target":""},"categories":[1],"tags":[],"aioseo_notices":[],"_links":{"self":[{"href":"http:\/\/www.thehistoricalarchive.com\/happenings\/wp-json\/wp\/v2\/posts\/54"}],"collection":[{"href":"http:\/\/www.thehistoricalarchive.com\/happenings\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"http:\/\/www.thehistoricalarchive.com\/happenings\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"http:\/\/www.thehistoricalarchive.com\/happenings\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"http:\/\/www.thehistoricalarchive.com\/happenings\/wp-json\/wp\/v2\/comments?post=54"}],"version-history":[{"count":0,"href":"http:\/\/www.thehistoricalarchive.com\/happenings\/wp-json\/wp\/v2\/posts\/54\/revisions"}],"wp:attachment":[{"href":"http:\/\/www.thehistoricalarchive.com\/happenings\/wp-json\/wp\/v2\/media?parent=54"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"http:\/\/www.thehistoricalarchive.com\/happenings\/wp-json\/wp\/v2\/categories?post=54"},{"taxonomy":"post_tag","embeddable":true,"href":"http:\/\/www.thehistoricalarchive.com\/happenings\/wp-json\/wp\/v2\/tags?post=54"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}