[ale] OT ntp - leap second - how many knew what this was 3 weeks ago

[Jim Kinney]

leap seconds are a counting problem not a calculation problem :-)


The orbital period of the earth is 365.256366 days, or 1.0000175 years

365.256366 days X 60 seconds/minute X 60 minutes/hr X 24 hours/day =
31558150.0224 seconds/year

so as long as the teacher will accept an answer in sidereal seconds...

31558150.0224 seconds/year X age in years + 86400 seconds/day X days
since last birthday = age in seconds.

On Sat, Jul 7, 2012 at 9:28 AM, Ron Frazier (ALE)
<atllinuxenthinfo at techstarship.com> wrote:
> Hi Justin,
>
> I found this interesting from the Wikipedia article:
>
> quote on ->
>
> For example, to compute the elapsed time in seconds between two given UTC
> past dates requires consulting a table of leap seconds, which needs to be
> updated whenever a new leap second is announced. Moreover, it is not
> possible even in theory to compute accurate time intervals for UTC dates
> that are more than about six months in the future.
>
> <- quote off
>
> A classic math problem some teachers might present to math or programming
> students is "find your age in seconds" etc. I now know that that's
> impossible in the past without a leap second table and totally impossible in
> the future.
>
>
> Sincerely,
>
> Ron
>
>
> --
>
> Sent from my Android Acer A500 tablet with bluetooth keyboard and K-9 Mail.
> Please excuse my potential brevity.
>
> (To whom it may concern. My email address has changed. Replying to former
> messages prior to 03/31/12 with my personal address will go to the wrong
> address. Please send all personal correspondence to the new address.)
>
> (PS - If you email me and don't get a quick response, you might want to
> call on the phone. I get about 300 emails per day from alternate energy
> mailing lists and such. I don't always see new email messages very quickly.)
>
> Ron Frazier
> 770-205-9422 (O) Leave a message.
> linuxdude AT techstarship.com
>
>
> Justin Goldberg <justgold79 at gmail.com> wrote:
>>
>> I knew that a year in "rotational time" lasts 365 days, 6 hours, and
>> 0.xx seconds. The 6 hours accounts for the leap day but I suppose the
>> leap second is only once every few years. I'll defer to wikipedia for
>> facts.
>>
>> http://en.wikipedia.org/wiki/Leap_second
>>
>>
>>
>> On 7/4/12, Ron Frazier (ALE) <atllinuxenthinfo at techstarship.com> wrote:
>> > Hi all,
>> >
>> > Around the beginning of this year, I was doing quite a bit of research
>> > into
>> > ntp and gps and eventually set up my own gps based ntp time server in
>> > both
>> > Linux and Windows. At the end of June, a leap second was inserted into
>> > the
>> > time sequences of the clocks on Earth. For those that may not know what
>> > that
>> > is, the atomic clocks are coordinated with the earth's rotation, so, for
>> > example, when the clock says noon, the sun is always roughly overhead.
>> > However, the earth's rotation speeds up and slows down at times.
>> > So,sometimes, we have to tweak the clocks to match the earth again. At
>> > the
>> > end of June, an extra second was inserted. Normally, the seconds go 58
>> > ...
>> > 59 ... 00. This time, they went 58 ... 59 ... 60 ... 00. As it turns
>> > out,
>> > this crashed a number of servers.
>> >
>> > I find this very interesting, and somewhat scary as a potential
>> > programmer.
>> > Since I'm thinking of learning programming again, and since I have an
>> > interest in timekeeping, I have considered writing a world clock program
>> > etc., to show the time in different parts of the world. However, prior
>> > to my
>> > NTP research, I never knew about the leap second. So, there would have
>> > been
>> > a good possibility, had I written the program prior to this year, that
>> > my
>> > program would have crashed as well.
>> >
>> > So, my question is, how many of you knew about leap seconds prior to
>> > this
>> > incidence of it and prior to my describing it. If you were writing a
>> > clock
>> > program, would you have known to account for this?
>> >
>> > Sincerely,
>> >
>> > Ron
>> >
>> >
>> > --
>> >
>> > Sent from my Android Acer A500 tablet with bluetooth keyboard and K-9
>> > Mail.
>> > Please excuse my potential brevity.
>> >
>> > (To whom it may concern. My email address has changed. Replying to
>> > former
>> > messages prior to 03/31/12 with my personal address will go to the wrong
>> > address. Please send all personal correspondence to the new address.)
>> >
>> > (PS - If you email me and don't get a quick response, you might want to
>> > call on the phone. I get about 300 emails per day from alternate energy
>> > mailing lists and such. I don't always see new email messages very
>> > quickly.)
>> >
>> > Ron Frazier
>> > 770-205-9422 (O) Leave a message.
>> > linuxdude AT techstarship.com
>> >
>>
>>
>> --
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>>
>> http://uberconference.com/zevcxTpX
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-- 
--
James P. Kinney III

Every time you stop a school, you will have to build a jail. What you
gain at one end you lose at the other. It's like feeding a dog on his
own tail. It won't fatten the dog.
- Speech 11/23/1900 Mark Twain

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