[time-nuts] SI Unit Problems

Magnus Danielson magnus at rubidium.dyndns.org
Wed Apr 6 19:11:05 UTC 2011


On 04/06/2011 03:19 PM, Jim Lux wrote:
> On 4/5/11 7:38 PM, Greg Broburg wrote:
>> The number 6 and derivations thereof were presented
>> to the world of science from the numerologists. Time
>> was arranged as parts of a day, 24 hours 60 minutes
>> per hour 60 seconds per minute. Very tenuous at best.
>> I propose that we consider 100 seconds in a minute,
>> 100 minutes in an hour, and 10 hours in a day. People
>> could handle that with an IPhone ap, right?
>
> Then there's the Babylonians, who used a number system where 60 was
> important. 60 has lots of factors, which makes dividing things up into
> equal sized chunks easy. (as my daughter said when much younger, and
> doing fractions in math, "curse those Babylonians").
>
> The fact that a year is about 360 days long (6*60) also feeds into it.
>
> You really needed the invention and adoption of place value for a
> decimalized system to work well, and that didn't come along til around
> 700-800 C.E., I think. By then, the fractional measurement approach and
> customary units were well entrenched. Sure, although King John
> standardized the yard and inch and pound and such in the 1200s, I'm sure
> that the units themselves were already in use for a long time. Currency
> is also done in a fractional system (pieces o'eight, 12pence/shilling
> with ha'pennies to boot)
>
> The French *did* have a decimalized calendar (and time, too, I think).

You can't do much about the the number of days per year, and a 400 day 
calender would be useless since it would be hard to pin things which 
depends on seasons to a fixed date, month or so...

Another annoying detail is that the SI second takes about 86400 seconds 
for a twist around the axis such that the closest star is at the same 
place in the sky again. If you want to get the closes decimal number it 
would be 100000 new seconds and such a second would require

86400 * 9192631770 / 100000 = 864 * 919263177 / 100 = 7942433849.28 
cycles per new second of a caesium reference. Not a particular "neat" 
number, but in reality it would not be too strange when considering how 
a caesium clock actually works.

Going full decimal is not practical. I does not support it.

Cheers,
Magnus




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