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U.S. Scientists Call for a Time Change
saqmaster writes "The BBC reported yesterday that U.S. scientists want to change the current system which keeps clocks in sync with solar time by adding a leap second every 18 months or so. This has rattled a few cages with the scientists and operators involved in GMT-related projects and facilities as it would effectively remove the importance of the meridian from timing. "
What the US scientists are suggesting is that we ignore the earth's rotation in our time-keeping, and just try to keep roughly in synch by arbitrarily adding leap-seconds (as opposed to adding them based on our actual observation of the slowing of the earth's rotation). i.e.: Noon will be when your shiny digital watch says it is, not when the sun is precisely above the prime meridian (or precisely X.X hours plus or minus from said event, depending on your timezone).
Dumb, dumb summary... the UK is defending the idea that humans (of both the blow-joe and the astronomical sort) base their sense of time on the earth's rotation... and so our method of time-keeping should do so as well.
God... what a dumb summary...
Akarsz Magyar Gentoo fórumot? Akkor
Like tinyurl, but one letter less! http://qurl.co.uk/
This seems in the same vein as the ICANN/Root Servers debate. Who controls things like this in an ever more connected world. My view is if it isn't broken why mess with it?
From the article it seems like the leap second is annoying but the leap hour is too much and not frequent enough. If it really that much trouble to keep resetting high precision clocks then why not compromise at leap 10 seconds or some other standard.
UTC or coordinated universal time (UTC is the acronym that was agreed on because the british and the french had a disagremment about the word order)is the standard time for the world. a time zone is 15 degress of longitude, and is equal to 1 hour. thus if you know the local time, and have a 0 point (Grenwich meridian) and can do some math, you know where on the planet you are.
UTC was agreed upon by an international body, many many years ago. it is now frowned upon to call it gmt (though pretty much everyone does)Not everyone follows it, and their are many variations (Newfoundland time - 30 minutes off)
some countries still have their own meridians.
time is tied to geography.
Since this is a "world" resource, time should no longer be managed by the UK, but by the UN standards body. Surely this will be a much more equitable and fair solution than hogging all of the world's time by one nation.
The Bureau international des poids et mesures is already responsible for measuring UTC as part of the SI system, by international treaty...
To summarise the summary of the summary: people are a problem. ~ h2g2
There's already a timescale called TAI which is just UTC without the leap seconds.
UTC was designed to be a compromise -- the leap seconds keep it within 0.9 seconds of UT1 (a rotational timescale), and it always differs from TAI by an integer number of seconds. Anyone who wants a purely monotonic timescale can use TAI.
Takes some getting used to, but when you are traveling across that country by train, it is *mighty* convenient
Um did you actually read the link you posted? That story is talking about a group of US scientists wanting to eliminate leap seconds and replace them with leap hours that are extremely far apart. This issue is just wanting to standardise the delay between leap seconds.
For a pretty full understanding of what is happening, what has happened, and why, see history of the effort, implications of change, definition of terms
Programmers of astronomical software already have trouble enough:
- The year -1 is followed by the year 1
- 4.10.1582 is followed by 15.10.1582, because only then the length of a year was measured with sufficient accuracy. The new system of leap years will only need a fix of one day in another thousand years.
- Last century Ephemeridical Time (ET) was introduced to serve as a constant measure of time (in contrast to the Universal Time (UT)). The commonly used time is UTC, which is running with the same "speed" as ET and being corrected every once in a while, when (UTC-UT) becomes greater than 0.9 seconds. Astronomical software has to know UT as well as the difference ET-UT: The positions of other planets have to be computed with ET and the rotational angle of the earth with UT.
ET-UT is more than 60 seconds at the moment already. Replacing UT/UTC with ET-60 s will not really make things easier and it will deprieve the old system of its benefits! If someone needs a ET-clock for doing satellite navigation, he shouldn't force everyone else to do so as well. If the U.S. scientists keep pushing, I'll switch to a russian time-server in the future.Who said anything about making half the world nocturnal? The only thing that would change by having a standard world time is the "time" people do their normal activities. Instead of going to work at 8:00 AM you might go in at 1:00 PM and work until 9:00 PM. Our time-keeping system already works this way, it just obfuscates it somewhat. The time zones are set up so that 8:00 AM CST is the same relative time of day (morning), as it is for people in China at 8:00 AM (it's morning for them though it's significantly off for people on the other side of the world). My time zone is GMT-5 so while people are just getting up for work at GMT, it's still very early morning for me and I'm fast asleep. What difference does it make if I go to work at 1:00 PM world time (still the same as 8:00 AM as far as I'm concerned) instead of 8:00 AM?
Just to be perfectly clear, everyone would still go to sleep when it was dark and everyone would still get up for work/school/whatever when it became light out again. It would just VASTLY simplify moving between our current time zones or communicating with people in a different one. If someone works from 12:00 AM to 8:00 AM world time and I work from 6:00 AM to 2:00 PM world time, it's going to be damn easy to know that 6:00 AM to 8:00 AM is the timeslot we have to work with for meetings.
BBC article completely misses the point. The international time reference, since the 1950's, has been UTC, and used tuned according
to atomic clocks, not the earth's rotation. There are time references used specifically for astronomy, such as sidereal time, solar time, etc... (http://en.wikipedia.org/wiki/Sidereal_time) There is absolutely no reason why astronomical time references have to match precisely to the time reference used by normal people.
The problem is that, today, there is no algorithm for knowing when to insert leap seconds ahead of time, which means you cannot calculate any time accurate to the second which is more than 18 months in the future, because you have no idea whether or not they will decide to insert a leap second. Nor is there any algorithm, other than a table of the known values to determine when to insert leap seconds. Add that they used to add them in June in some years, and December in others, and sometimes had two in the same year, and you get a feel for how chaotic it is.
Accumulate these differences over twenty years, and you have a serious problem. That is why the global positioning system uses it's own time reference, which has no leap seconds. When you're calculating position based on propagation delays, leap seconds are a mess. so GPS time is currently (http://tycho.usno.navy.mil/gpstt.html) fourteen or fifteen seconds different from UTC. (how many leap seconds since 1999? no way to calculate, you just have to know.) Seconds are the basis for all computer based time scales. These little nudges make very little sense. It would be far smarter to insert a leap minute, every... oh... 90 years. Or make the leap second insertion an algorithmic event, and not some random decision negotiated among a committee of astronomers.
It basically means that there is no way to build an embedded software and leave it running disconnected from anything and maintain high time accuracy at the same time.
1 second is 18 months is 21 parts per billion.
If your clock needs to drift less than one second in 18 months, then you're already using an atomic clock or primary or secondary time source. This means that you are also going to go to the trouble of synchronizing your clock with some external standard that is, eventually, a primary clock.
If you can't get the leap second information from your primary time source, then it doesn't matter if you lose 1 second over 18 months - unless you have an atomic clock on board you're going to drift that much in shorter than 18 months. If you have a cheap atomic clock you may still drift that much.
-Adam
"is a time service that transmits from Boulder Colorado"
As a resident of Fort Collins, CO and (now) Boulder, CO, let me clarify:
WWV transmits from Fort Collins, CO on 2.5, 5, 10, 15, and 20 MHz. You need a shortwave radio to pick it up (though, in the Fort Collins area, you can pick it up on a crappy AM radio tuned to the upper end of the band).
NIST is located in Boulder, CO, and it serves as the frequency and time reference for the atomic clocks in Fort Collins.
WWVB is also transmitted from Fort Collins, CO, providing a digital time service for radio-synchronized clocks. If you care about having the right time, these are a cheap way to get it.
http://www.swatch.com/internettime/
Actually, to be perfectly accurate, they will get an extra pip at 2005-12-31 23:59:60.
It refers to startrek. Theirs been some speculation about how to convert and use it. The best so far use conversions such as d/m/y * 0.5 + (x*3) tacked to the end where x is convention time expressed as a 24 hour clock.