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DATETIME  November 2015

DATETIME November 2015

Subject:

Time Zones

From:

"Edward C. Zimmermann" <[log in to unmask]>

Reply-To:

Discussion of the Developing Date/Time Standards <[log in to unmask]>

Date:

Wed, 25 Nov 2015 12:26:55 +0100

Content-Type:

text/plain

Parts/Attachments:

Parts/Attachments

text/plain (170 lines)

I'd like to elaborate on my Perl Harbour attack example:

"Example in 1941 Honolulu was UTC- 10.5 (so-called -10:30) and it is 
currently UTC-10. The attack on Perl Harbour is typically reported as 7:48 
AM local time."

7 Dec 1941 07:48 Honolulu time was 6 Dec 1941 19:18 GMT.
Standard Hawaii time changed in 1948 from -10:30 to -10.

We have loads of historical data that lists place, date and time. 
Unfortunately even in the 19th century things were quite confusing. The US 
had over 300 different time "standards"! It was as late as November 18, 
1883 that unified and standard time zones were introduced in the US.

Remember my example about "When did Lincoln die"? April 15 1865 in 
Washington DC. The time was reported as 7:22 AM.
What is that date and time normalized to GMT--- leaving off that GMT as we 
know it was first adopted in 1884?

What is the precision? I would argue that we only know the time that was 
reported. In other words "It was reported that he died at 7:22 AM in 
Washington DC" and not "he died at 7:22 AM Washington time". Semantics is 
beyond the scope of our discussions so we need to focus on precision, 
reliability, repeatability etc..
The minute measure itself is not bad.. I think I wrote about the evolution 
of the Bablyonian system some years ago... With astronomical observations 
we had quite early a kind of traceable accuracy that we did not have with 
lengths and weights....

Look at those historical measures.. What is a foot? Historically it was 
some local standard that measured in today's metric lengths somewhere 
typically between 250mm and 335mm subdivided into 12 sub-units. Literature 
is filled with feet, els, cubits, pounds, grains etc. The El and Cubit 
were, interestingly, not the same. The measurement of length is the 
precision of the observation of the human body.

In Numbers 35:5

http://www.chabad.org/library/bible_cdo/aid/9963/jewish/Chapter-35.htm

"You shall measure from outside the city, two thousand cubits on the 
eastern side, two thousand cubits on the southern side, two thousand cubits 
on the western side, and two thousand cubits on the northern side, with the 
city in the middle; this shall be your cities' open spaces."

What was the area in sq meters? :-)





 









On Tue, 24 Nov 2015 17:00:20 -0500, Denenberg, Ray wrote
> Google "Time at Baker Island".   Then Google "Time at Marshall Islands".   
I got 9:58 Wednesday  on one and 11:58 Tuesday on the other. .
> 
> > -----Original Message-----
> > From: Discussion of the Developing Date/Time Standards
> > [mailto:[log in to unmask]] On Behalf Of Edward C.
> > Zimmermann
> > Sent: Tuesday, November 24, 2015 2:40 PM
> > To: [log in to unmask]
> > Subject: Re: [DATETIME] 1/27 conference call notes: an instant can't be 
on 3
> > different days
> > 
> > On Tue, 24 Nov 2015 13:56:03 -0500, Denenberg, Ray wrote
> > > > From  [UTF-8?]SaaÅ¡ha Metsärantala
> > >
> > > > date -d '2015-11-22T23:00:00-12:00' +%s
> > >
> > > >
> > >
> > > > date -d '2015-11-23T12:00:00+01:00' +%s
> > >
> > > >
> > >
> > > > date -d '2015-11-24T01:00:00+14:00' +%s
> > >
> > > But UTC-12 is the same zone as UTC+12, isn't it.  So the above three
> > would be:
> > 
> > 
> > The clock time is the same but the day is different.
> > 
> > Right now it is:
> > 
> > 07:30 AM Wednesday, 25. November 2015 (GMT+12)
> > 
> > 07:30 AM Tuesday, 24. November 2015 (GMT-12)
> > 
> > Baker Island and the Marshall Islands are right now on two different 
days
> > (Weds and Tues)!
> > 
> > >
> > > 2015-11-23T12:00:00+01:00
> > >
> > > 2015-11-22T23:00:00+12:00
> > >
> > > 2015-11-24T01:00:00+14:00
> > >
> > > And +12 is between +1 and +14, meaning that it will be the same day 
as
> > either the first or third.
> > >
> > > > > '1-1-1980/12-31-1980'
> > >
> > > >
> > >
> > > > > ..... is as close as you will get with the edtf spec: the 
interval
> > beginning
> > >
> > > > some time during 1-1-1980 and ending some time during 12/31/1980.
> > >
> > > > Likewise
> > >
> > > >
> > >
> > > > 1980-01-01T00:00:00Z/1980-12-31T24:00:00Z
> > >
> > > >
> > >
> > > > would be the duration between (1) some instant during the first 
second
> > of
> > >
> > > > the year 1980 and (2) the very last instant of that year. In other
> > words, it
> > >
> > > > would be between 31622399 and 31622400 seconds long, depending om
> > >
> > > > "when" (during that second) within 1980-01-01T00:00:00 the measure
> > was
> > >
> > > > made. There were no leap seconds that year.
> > >
> > > EDTF does not profile time within an interval, only dates.  So my 
point
> > was that using the EDTF spec, that's the closest you'll get, but you 
can go
> > outside EDTF and 8601 allows time within an interval.
> > >
> > > --Ray
> > 
> > 
> > --
> > 
> > Edward C. Zimmermann, NONMONOTONIC LAB


--

Edward C. Zimmermann, NONMONOTONIC LAB/BSn
  Jakob Klar Strasse 8, D-80796 Munich,
  Federal Republic of Germany
Telephone:=  +49 (89) 46 22 2043    Mobile:= +49 (176) 100-360-55
http://www.ibu.de/IB_Engine
Umsatz-St-ID: DE130492967

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