Path: csiph.com!feeder.erje.net!1.us.feeder.erje.net!news.alt.net From: "James Wilkinson Sword" Newsgroups: alt.comp.hardware.pc-homebuilt,comp.lang.c,comp.lang.ada,comp.programming,alt.comp.os.windows-10,alt.os.linux.ubuntu Subject: Re: 'Leap Second' to Be Added on New Year's Eve This Year Date: Wed, 04 Jan 2017 15:44:10 -0000 Organization: ~ Lines: 67 Message-ID: References: <5f5afd36-1ba2-f4e2-62ef-57a652f3170c@verizon.net> Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8; format=flowed; delsp=yes Content-Transfer-Encoding: Quoted-Printable User-Agent: Opera Mail/1.0 (Win32) Xref: csiph.com alt.comp.hardware.pc-homebuilt:35513 comp.lang.c:101100 comp.lang.ada:32691 comp.programming:7252 alt.comp.os.windows-10:32581 alt.os.linux.ubuntu:194658 On Wed, 04 Jan 2017 01:06:06 -0000, James R. Kuyper wrote: > On 12/31/2016 04:57 PM, James Wilkinson Sword wrote: >> On Thu, 22 Dec 2016 13:43:58 -0000, Mr. Man-wai Chang wrote: > ... >>> A "leap second" will be added to the world's official clocks on Dec.= 31 >>> at 23 hours, 59 minutes and 59 seconds Coordinated Universal Time (U= TC), >>> which corresponds to 6:59:59 p.m. EST; the clocks will read 23:59:60= >>> before ticking over to midnight. The goal is to keep two different >>> timescales in sync with each other. >>> >>> The units of time had long been defined based on Earth's rotation >>> relative to distant celestial bodies. But that changed with the >>> invention of atomic clocks in the mid-20th century; scientists then >>> decided to base the second on the natural vibrations of the cesium a= tom. >>> [How to Build the Most Accurate Atomic Clocks (Video)] >>> >>> These two timescales don't match up exactly, however. Measurements s= how >>> that, because the moon's gravitational pull and other factors are >>> gradually slowing Earth's spin, the rotation-based scale loses betwe= en >>> 1.5 and 2 milliseconds per day compared to atomic time =E2=80=94 mea= ning the two >>> diverge by a full second every 500 to 750 days. >>> >>> Leap seconds are a way to make up for this difference. Since 1972, t= he >>> International Earth Rotation and Reference Systems Service (IERS) =E2= =80=94 the > > That name always struck me as rather funny - it seems to imply that > they're responsible for making the Earth rotate. What they're actually= > responsible for is keeping track of the Earth's rotation. I am now imagining someone turning an ignition key and cursing. >>> organization that keeps track of time for the world =E2=80=94 has ad= ded 26 leap >>> seconds to atomic clocks, with the last such insertion coming on Jun= e >>> 30, 2015. >>> >>> The aim is to keep the two timescales within 0.9 seconds of each o= ther. > ... >> I wish they'd turn their attentions to not turning the clocks back an= d forth all the fucking time! > > If you could make the Earth rotate at a fixed rate, there would be no > need for leap seconds. It's perfect feasible, though the costs would b= e > astronomical. Would you care to pay enough in taxes to make that happe= n? Rotation rate is nothing to do with DST. -- = Hard work pays off in the future. Laziness pays off now.