[time-nuts] Re: UTC - A Cautionary Tale
Mike S
mikes at flatsurface.com
Sun Jul 17 19:03:09 EDT 2005
At 06:24 PM 7/17/2005, obyrne at iol.ie wrote...
>>>simple arithmetic with a timescale with a variable second would give an
>>>order of magnitude better estimate of the amount of time between 2005 Dec 31
>>>23:59:59.9 and 2006 Jan 01 00:00:00.1 than UTC does!
>>
>>UTC will tell you that there is EXACTLY 1.2 seconds between those two points.
>
>The kind of "simple arithmetic" that I was thinking about precludes the use of look-up tables.
Yet you consider quadratic equations to be "simple arithmetic?"
>My suggestion does not call for a "loosely defined" second - it calls for
>a variable second, PRECISELY tied to TAI. In other words,
>time = a + b*TAI + c*TAI^2, where a, b and c are fixed constants
You'll need more than that. For a fixed set of coefficients, even for a limited period (~200 years) and relaxed sync with UT1 (2.3 vs. 0.9 seconds) it takes a 12th order polynomial. http://www.phys.uu.nl/~vgent/astro/deltatime.htm Of course, that's the best that's been done with 100% hindsight - as they say: "Past performance is no guarantee of future results."
I think a lookup table is simpler, more precise and longer lasting. As you pointed out, with the current rules, it should last about 1000 years. If the rules are relaxed to allow leap seconds more often than 1/mo, much longer than that.
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