{"id":4582,"date":"2003-08-04T10:50:42","date_gmt":"2003-08-04T17:50:42","guid":{"rendered":"http:\/\/hill-kleerup.org\/blog\/wp\/?p=4582"},"modified":"2003-08-04T10:50:42","modified_gmt":"2003-08-04T17:50:42","slug":"does_anybody_kn","status":"publish","type":"post","link":"https:\/\/hill-kleerup.org\/blog\/2003\/08\/04\/does_anybody_kn.html","title":{"rendered":"Does anybody know what time it is?"},"content":{"rendered":"

Well, no, actually they don’t<\/a>.<\/p>\n

I get really annoyed by the 3-5 minute difference between my computer and the time display on my office phone. But that’s just annoyance. <\/p>\n

The real trouble comes between trying to impose digital accuracy on an analog world — or trying to make a constant (vibrational frequency of atoms, the foundation for atomic clocks) match up to a variable (the rotation of the Earth). We use atomic clocks instead of the rotation because it is <\/i>a variable — over time it’s slowing down, and not even at a constant rate — but as atomic timekeeping is becoming more widespread, that discrepency is becoming more of a problem.<\/p>\n

The problem arises because the Earth cannot keep time as accurately as modern atomic clocks, which count the steady shaking of atoms. These atomic clocks replaced the motion of the Earth as the world’s official timekeeper in 1967. The pull of the moon is gradually slowing our planet down, so every now and then our clocks are halted for a second to let it catch up.
\nThe first of these “leap seconds” was introduced in 1972, mainly as a favour to astronomers and others who still relied on the old-style celestial time. A further 31 leap seconds have been added since, most recently on December 31 1998.
\nAnd that would be that, were it not for the fact that the precise timekeeping offered by atomic clocks is now becoming widely available – most commonly through the satellite global positioning system used for navigation. To add to the confusion, GPS uses yet another timescale.
\nIt includes the leap seconds added until the GPS clock was set in 1980, but has ignored those added since. This means GPS time is now running 13 seconds ahead of coordinated universal time – which includes all added leap seconds and to which most clocks on Earth are set – but is some 19 seconds behind international atomic time, which is based on atomic clocks and ignores leap seconds.<\/p>\n

If you consider how far a jet aircraft can move in 13-19 seconds, you can catch a glimpse of some of the problems.<\/p>\n

And, of course, the Europeans are (unilaterally) going to have a different system\/benchmark when they launch their own GPS system.<\/p>\n

Naturally, the real threat is the lawyers getting involved.<\/p>\n

“We face possible problems in the timestamping of electronic documents,” [Dennis McCarthy of the US Naval Observatory] says. This is because a leap second is usually added at the end of the day, by asking clocks to change from 23:59,59 to 23:59,60 before going on to 00:00,00. But as most clocks don’t permit the number 60, they show 23:59,59 for two seconds instead.
\n“I suspect it will happen eventually that someone says their 23:59,59 refers to a different 23:59,59 and lawyers will become involved,” Mr McCarthy says. This could be important for legal or financial documents detailing the sale of bonds and securities at a specific time.<\/p>\n

The techies are looking at a simple answer — banning leap seconds. Then everything is nice and neat and simple — except for trivial matters like the real world. Not only would it throw astronomical observations for a loop, but eventually you’d have a discrepency between when the sun rises and when the almancs say it should rise. Ultimately, day and night on the clock would fail to correlate with the sun in the sky.<\/p>\n

To stop this happening, we would need to introduce a leap hour every 700 years or so, in a similar way to how we change our clocks to account for summertime.<\/p>\n

I suspect that worrying about what folks 700 years from now will have to do will be a non-starter for the wonks who figure this out.<\/p>\n

(via BoingBoing<\/a>)<\/small><\/p>\n","protected":false},"excerpt":{"rendered":"

Well, no, actually they don’t. I get really annoyed by the 3-5 minute difference between my computer and the time display on my office phone. But that’s just annoyance. The…<\/p>\n","protected":false},"author":2,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"_seopress_titles_title":"","_seopress_titles_desc":"","_seopress_robots_index":"","_seopress_robots_follow":"","_seopress_robots_imageindex":"","_seopress_robots_snippet":"","_seopress_robots_primary_cat":"","_seopress_robots_breadcrumbs":"","_seopress_robots_freeze_modified_date":"","_seopress_robots_custom_modified_date":"","_seopress_robots_canonical":"","_seopress_social_fb_title":"","_seopress_social_fb_desc":"","_seopress_social_fb_img":"","_seopress_social_fb_img_attachment_id":0,"_seopress_social_fb_img_width":0,"_seopress_social_fb_img_height":0,"_seopress_social_twitter_title":"","_seopress_social_twitter_desc":"","_seopress_social_twitter_img":"","_seopress_social_twitter_img_attachment_id":0,"_seopress_social_twitter_img_width":0,"_seopress_social_twitter_img_height":0,"_seopress_redirections_value":"","_seopress_redirections_enabled":"","_seopress_redirections_enabled_regex":"","_seopress_redirections_logged_status":"","_seopress_redirections_param":"","_seopress_redirections_type":0,"_seopress_analysis_target_kw":"","_jetpack_memberships_contains_paid_content":false,"footnotes":"","jetpack_publicize_message":"","jetpack_publicize_feature_enabled":true,"jetpack_social_post_already_shared":false,"jetpack_social_options":{"image_generator_settings":{"template":"highway","default_image_id":0,"font":"","enabled":false},"version":2}},"categories":[6],"tags":[],"class_list":["post-4582","post","type-post","status-publish","format-standard","hentry","category-science"],"jetpack_publicize_connections":[],"jetpack_featured_media_url":"","jetpack_sharing_enabled":true,"jetpack-related-posts":[{"id":39095,"url":"https:\/\/hill-kleerup.org\/blog\/2013\/10\/08\/4-of-5-stars-to-atomic-robo-an.html","url_meta":{"origin":4582,"position":0},"title":"4 of 5 stars to Atomic Robo an…","author":"***Dave","date":"Tue 8-Oct-13 4:59pm","format":false,"excerpt":"4 of 5 stars to Atomic Robo and the Dogs of War by Brian Clevinger http:\/\/t.co\/K7EAaSuBN2","rel":"","context":"In "~Tweets"","block_context":{"text":"~Tweets","link":"https:\/\/hill-kleerup.org\/blog\/category\/blogging\/tweets"},"img":{"alt_text":"","src":"","width":0,"height":0},"classes":[]},{"id":133721,"url":"https:\/\/hill-kleerup.org\/blog\/2017\/06\/22\/another-step-closer-to-fusion-power.html","url_meta":{"origin":4582,"position":1},"title":"Another step closer to fusion power","author":"***Dave","date":"Thu 22-Jun-17 12:38pm","format":false,"excerpt":"The problem is, there's always been another step closer, and another step after that, and another step after that.I've been in love with the idea of fusion for power since debating about it back in high school. Fusion is tremendously exciting as a power source -- but also tremendously hard\u2026","rel":"","context":"In "~PlusPosts"","block_context":{"text":"~PlusPosts","link":"https:\/\/hill-kleerup.org\/blog\/category\/blogging\/plusposts"},"img":{"alt_text":"","src":"","width":0,"height":0},"classes":[]},{"id":49298,"url":"https:\/\/hill-kleerup.org\/blog\/2015\/01\/21\/atomic-robo-is-switching-over-to-being-a-web-comic.html","url_meta":{"origin":4582,"position":2},"title":""Atomic Robo" is switching over to being a web comic","author":"***Dave","date":"Wed 21-Jan-15 6:06am","format":false,"excerpt":"And all of its back issues will be available free, online. Cool beans -- I love this comic, a snappy Weird Science series which has a similar vibe to Hellboy, only with a nuclear-powered robot built by Nikola Tesla as the irreverent, hard-punching protagonist.Check out more at http:\/\/www.atomic-robo.com\/ . Atomic\u2026","rel":"","context":"In "~PlusPosts"","block_context":{"text":"~PlusPosts","link":"https:\/\/hill-kleerup.org\/blog\/category\/blogging\/plusposts"},"img":{"alt_text":"","src":"","width":0,"height":0},"classes":[]},{"id":233,"url":"https:\/\/hill-kleerup.org\/blog\/2003\/05\/21\/better_living_t.html","url_meta":{"origin":4582,"position":3},"title":"Better living through nukes","author":"***Dave","date":"Wed 21-May-03 2:22pm","format":false,"excerpt":"Here's an amazing 1957 \"Atomic Revolution\" comic book, lovingly scanned (large images warning) for your viewing pleasure. Since one pound of uranium can do the job of 1,300 tons of...","rel":"","context":"In "Science & Nature"","block_context":{"text":"Science & Nature","link":"https:\/\/hill-kleerup.org\/blog\/category\/science"},"img":{"alt_text":"","src":"","width":0,"height":0},"classes":[]},{"id":128239,"url":"https:\/\/hill-kleerup.org\/blog\/2015\/10\/05\/the-nevada-atomic-test-site.html","url_meta":{"origin":4582,"position":4},"title":"The Nevada Atomic Test Site","author":"***Dave","date":"Mon 5-Oct-15 2:41pm","format":false,"excerpt":"A look at where the US did its A-bomb and H-bomb testing in the 50s through the 70s, in a set of short films (which start up automatically as you scroll down).Eerie is the only word I can use for it. Building the atom bomb: the full story of the\u2026","rel":"","context":"In "~PlusPosts"","block_context":{"text":"~PlusPosts","link":"https:\/\/hill-kleerup.org\/blog\/category\/blogging\/plusposts"},"img":{"alt_text":"","src":"","width":0,"height":0},"classes":[]},{"id":27039,"url":"https:\/\/hill-kleerup.org\/blog\/2012\/03\/11\/i-would-gladly-spend-4yr-to-not-change-the-clocks-forward-and-backreally.html","url_meta":{"origin":4582,"position":5},"title":"I would gladly spend $4\/yr to not change the clocks forward and backReally","author":"***Dave","date":"Sun 11-Mar-12 11:57am","format":false,"excerpt":"I would gladly spend $4\/yr to not change the clocks forward and back Really. Who can I make the check out to? #ddtb","rel":"","context":"In "~PlusPosts"","block_context":{"text":"~PlusPosts","link":"https:\/\/hill-kleerup.org\/blog\/category\/blogging\/plusposts"},"img":{"alt_text":"","src":"","width":0,"height":0},"classes":[]}],"_links":{"self":[{"href":"https:\/\/hill-kleerup.org\/blog\/wp-json\/wp\/v2\/posts\/4582","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/hill-kleerup.org\/blog\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/hill-kleerup.org\/blog\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/hill-kleerup.org\/blog\/wp-json\/wp\/v2\/users\/2"}],"replies":[{"embeddable":true,"href":"https:\/\/hill-kleerup.org\/blog\/wp-json\/wp\/v2\/comments?post=4582"}],"version-history":[{"count":0,"href":"https:\/\/hill-kleerup.org\/blog\/wp-json\/wp\/v2\/posts\/4582\/revisions"}],"wp:attachment":[{"href":"https:\/\/hill-kleerup.org\/blog\/wp-json\/wp\/v2\/media?parent=4582"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/hill-kleerup.org\/blog\/wp-json\/wp\/v2\/categories?post=4582"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/hill-kleerup.org\/blog\/wp-json\/wp\/v2\/tags?post=4582"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}