[LEAPSECS] Cost: getting rid of GMT & discontinuing leap seconds
mgy1912 at cox.net
Mon Oct 25 14:17:17 EDT 2010
From: "Rob Seaman" <seaman at noao.edu>
Sent: Monday, October 25, 2010 7:53 AM
To: "Leap Second Discussion List" <leapsecs at leapsecond.com>
Subject: Re: [LEAPSECS] Cost: getting rid of GMT & discontinuing leap
> On Oct 25, 2010, at 12:01 AM, Brian Garrett wrote:
>> More accurately, civil timekeeping is sorta kinda like mean solar time.
>> For now.
> See numerous (perhaps beyond count) threads from the archives.
> One more time. The entire reason that the ITU-R scheme can be
> contemplated is that the SI "second" (what should have been called the
> "essen") was mistakenly sized "sorta kinda like" the Babylonian second
> (1/60 of 1/60 of 1/24 of a day). Sure the ITU-R can cheat for a while for
> some purposes, but this is only because for that period for those purposes
> an "SI day" (a non-existent unit) is close enough to resemble the actual
> mean solar day (a unit predating mathematics). Interval time shouldn't
> even be represented with sexagesimals (a way of expressing angles).
> Etc and so forth.
>> There's no reason that couldn't change. If legislators were somehow to
>> be convinced that TAI or GPS time were the way to go, then that's what
>> they'd impose and that's what _hoi polloi_ would use.
> Legislators can attempt to impose all sorts of things. Over the long
> term, the true underlying natural "requirements" (in the engineering
> sense) will reveal themselves.
Over the VERY long term, yes. Over a human lifespan no.
> Another name for "hoi polloi" is "citizens" or "customers".
>> Indeed, I can totally imagine how that could happen, especially since
>> they already think imposing an offset of 216000 seconds for seven months
>> out of the year is a good idea.
> Confuses periodic and secular effects. Apparent solar time is a red
> herring. Mean solar time is simply the natural sidereal period of the
> Earth adjusted for one day "lost" each year lapping the Sun.
> Have no idea what the number 216000 seconds (2.5 days) is supposed to
I should have said 3600 seconds. One hour. The amount of a DST offset.
>> Anybody who uses UTC professionally and does not live in a place where
>> UTC is the local zone time has already divorced themselves from local
>> mean solar time. So has any location that uses summer/daylight saving
> UTC is the zero point for the entire standard zone civil timekeeping
> system. It is one unified whole. It is the existence of an underlying
> common timescale that permits separate time zones and variations like
> daylight saving time to function.
Which could still work if a monotonic time scale like TAI were legislated.
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