From a computer engineering point of view, who cares about how computers
Hey Jay,
Obviously a lot of food for thought here.
track time, they really don't care what time of the day it is, or what day
it is in the week, they just do their thing. And that''s just like with
the power system, Transpower NZ's grid works day and night and the
protection around it will operate day and night, hey what happened at
Huntly Powerstation the other week, would have happened anytime, it just
happens that we tend to use more electricity during the day.
So, there's two points to this...
1. The amount of time it takes the earth to rotate around it axis
2. The amount of time it takes the earth to orbit around the sun
If I'm correct...
1. It takes 24 Hours for the planet to completely rotate 360 degrees around
it's axis.
2. It takes 365.25 days for the earth to orbit around the sun...
The whole idea of 29th February to happen once every 4 years is to
compensate for the extra time it required for the earth to orbit around the
sun, which has worked well for a number of years and suits me just fine.
OTOH, lengthening then day to compensate for the time for the earth to
orbit around the sun is going to create a lot more problems that it's
worth, for starters lets throw out all the other timezones, and let's write
a script as to when it's time to come to work, brew a coffee, have lunch,
then open a beer. Also, I might as well throw away my navigation charts,
and for those of you that have done at least your PPL cross-country flying
will know where I'm going with this...
I agree with that if anything is devised that it should be it's own
timezone rather than UTC redefined.
On Fri, Dec 23, 2011 at 11:19 AM, Jay Daley
A network time heads-up.
There has been a debate raging for some years on whether or not to change Universal Coordinated Time (UTC) to be the same as International Atomic Time (TAI), which is due for a major vote at the ITU-R in January. Previous votes have seen it defeated but it keeps coming back.
To explain the background: The rotation of the earth is not precisely the same length of time each year and currently a decison is made every six months whether or not to correct UTC to ensure that midday really is when the sun is at its highest point over the Greenwich meridian, by adding a leap second. 24 have been added over the last 40 years and UTC now differs from TAI by 34 seconds. The proposal, if agreed, will drop this correction and so over a long time the connection between time and the rotation of the earth will be lost.
The implication for networks is potentially quite profound. NTP currently supports leap seconds as do GPS satellite time signals and DCF77 radio clocks but if this proposal is agreed that will be turned off. So if you provide time to a system that take a photograph at the same time every day then that will need two time signals, one for TAI and a new one for earth rotation time. Same problem for anything to do with sun rises/falls and tides (though obviously the precision may not be an issue for some years).
If you want to read more then this article covers the arguments quite well, though biased like me against the idea: http://www.bloomberg.com/news/2011-12-22/un-vote-could-allow-mankind-to-cont...
I'm not sure if NZ has a position on this, but I am trying to find out.
cheers Jay
PS A reminder about our free NTP service, details at: www.ntp.net.nz PPS If you think this is off-topic for this list then please let me know!
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