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End of the Leap Second

a_unique_person

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a_unique_person
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Who wins, commercial considerations or science?

http://www.post-gazette.com/pg/05210/545823.stm

It would be a very short sighted decision to drop the leap second practice.

What time is it when the clock strikes half past 62?

Time to change the way we measure time, according to a U.S. government proposal that businesses favor, astronomers abominate and Britain sees as a threat to its venerable standard, Greenwich Mean Time.

Word of the U.S. proposal, made secretly to a United Nations body, began leaking to scientists earlier this month. The plan would simplify the world's timekeeping by making each day last exactly 24 hours. Right now, that's not always the case.

Because the moon's gravity has been slowing down the Earth, it takes slightly longer than 24 hours for the world to rotate completely on its axis. The difference is tiny, but every few years a group that helps regulate global timekeeping, the International Earth Rotation and Reference Systems Service, tells governments, telecom companies, satellite operators and others to add in an extra second to all clocks to keep them in sync. The adjustment is made on New Year's Eve or the last day of June.

But adding these ad hoc "leap seconds" -- the last one was tacked on in 1998 -- can be a big hassle for computers operating with software programs that never allowed for a 61-second minute, leading to glitches when the extra second passes. "It's a huge deal," said John Yuzdepski, an executive at Symmetricom Inc., of San Jose, Calif., which makes ultraprecise clocks for telecommunications, space and military use.
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What will happen to the "new" daylight savings time now?

Do I hope for too much when I think a metric standard may follow?
 
A metric standard what?

Pop song?
Poem?
Second?

Seconds are already metric. There are 1000 milliseconds in a second.:D
 
"Hey, let's make the most used time unit, the second, dependant on the rotational speed of the earth!"

That means tasks will be accomplished in less seconds than before and since the meter is dependant on the second and the speed of light stuff will start getting shorter too!

What a wonderful idea!
 
The reason for leap-seconds and indeed leap-years is to make sure that the days remain in alignment and more importantly, the seasons do not drift.
A seasonal drift would make the farmers life a bit complicated.

The obvious solution to this would be for companies which rely on exact syncronisation to adjust their clocks at a time of their choosing.
They already have to cope with Daylight Savings Time shifts, which I know can be a nightmare for computer systems ( It is known as the 'witching hour', where spooky things start to happen to scheduled jobs )
 
I think farmers can handle a few seconds every decade. In 600 years I think they can handle getting up a few minutes early.

Alkatran, you actually have it backwards. A day will be exactly 24 hours as defined by the vibration of cesium atoms (unless they upgraded to whatever it is that's more accurate), but a day will drift out of alignment with the earth's rotation. So in a few thousand years, for example, the time when the sun is at it's highest point during the day will be 1 rather than 12. Very irritating for astronomers, who like to know what direction the earth is facing more than anything else.
 
Word of the U.S. proposal, made secretly to a United Nations body, began leaking to scientists earlier this month.
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Sure. They were going to change the way people measure time, but without mentioning it to those pesky scientists.
 
The astronomers are not convinced. "If your navigation system causes two planes to crash because of a one-second error, you have worse problems than leap seconds," said Steve Allen, a University of California astronomer who maintains a Web site about leap seconds
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Well, it dpesn't seem to really be planes crashing, but this would cause a hell of a mess for just about everything, espescially military. Guided missles, global positioning systems. Lots of stuff. The "cheap" solution would be to have two time systems: one sun based, the other math based. That way software can work on a solely math based time system with regular known adjustments. But as applications that use these systems (especially military) become more space oriented, the relation of objects relative to the sun will become increasingly important. Two seperate time systems opens up great risk to software that doesn't use the "right" system. Can't there be devised a math system (using fractions) that would correspond to a sun system?
 
The Earth and Sun do not make great time-pieces, since there is too much going on in the solar system that can drift the times involved.
Plus the fact that the number of solar days per year is not a nice round figure.

The idea of two time streams is interesting. The normal world could operate on solar time and any time sensitive applications could work on their own universal atomic clock time.
There would eventually be some drift, but it would be accurately known and accountable.
It would, however, require some funky algorithms to convert the atomic clock time back into solar time!!

Certainly, GPS systems would benefit from this, because they are highly dependant on time syncronisation. The only problem would be to make sure the satellite positions are syncronised properly with the GPS almanac, since it would start to drift.
 
I agree that the simplest solution is to have a World time, based on the atomic time standard, and a separate astronomical time that works with the odd leap second, as at present.

All we need is a server on the internet that allows us to look up the offset between astronomical time and universal time. If and when this offset gets to be really significant, say half an hour or so, then the universal time clock could be adjusted to bring it back in synch with the Earth.

The half-hour adjustment would be a big deal, but we won't need to do it for several decades/centuries at least. By the time we do need to do it, computer systems will be better, and it might be easier anyway.
 
Dilb said:
I think farmers can handle a few seconds every decade. In 600 years I think they can handle getting up a few minutes early.

Alkatran, you actually have it backwards. A day will be exactly 24 hours as defined by the vibration of cesium atoms (unless they upgraded to whatever it is that's more accurate), but a day will drift out of alignment with the earth's rotation. So in a few thousand years, for example, the time when the sun is at it's highest point during the day will be 1 rather than 12. Very irritating for astronomers, who like to know what direction the earth is facing more than anything else.
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Well I figured that they would also want to keep the 60 s/min and 60 min/hr conversions. So I figured the bill would end up redefining the second... :(
 
Someone remind me, what does a law in America have to do with New Zealand & the rest of the world?
 
DavoMan said:
Someone remind me, what does a law in America have to do with New Zealand & the rest of the world?
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Excellent point.

So this is a US Government proposal that suggests a course of action that will take America out of time alignment with the rest of the world?

Great plan.

Well while it is still only considered a "huge deal" by the executives of companies that make 'ultraprecise' clocks, I don't think I'll worry too much about it.

We seem to have managed okay with just one time stream up until now, and bearing in mind the rest of the world will say 'sod off' to such a suggestion then I can't see this as imminent.

Bearing in mind we haven't managed to standardise weight, length, height, temperature or volume yet then I think the urge to complicate the average person's measurement of time may meet with a little bit of resistence.
 
A number of different timescales already exist, some with leap seconds and some without. In principle, there is no problem: just use whichever one you want. The practical problem is that many computer programs currently exist which were written by programmers who didn't really know what they wanted. They never heard of leap seconds, so their programs don't know how to deal with them. But their programs happen to end up using UTC, a timescale that does have leap seconds, simply because UTC is the most common timescale.

The question is, should UTC no longer have leap seconds inserted? Either way, a bunch of programs will have to be rewritten. It just depends on which way will result in the least amount of rewriting, or will cause the least amount of serious problems should failures occur in programs that need to be rewritten but aren't.
 
This is what can happen when you take a capricious attitude toward accurate and precise timekeeping:
When the Patriot system is in operation, it must have a way of determining whether "targets" it finds in the air are actually incoming missiles rather than false alarms. The Patriot makes this determination by tracking the target to determine whether it is following the expected path of a ballistic missile. Ballistic missiles travel at extremely high speeds, which means that the time interval between radar "sightings" of the target must be very small. The Patriot tracks a target by first noting the location of the original radar sighting, then by using knowledge of the characteristics of a ballistic missile in flight to anticipate where the target should be at the next radar sighting--a fraction of a second later. If, at the second radar sighting, the target does not appear in the "range gate," the calculated zone in which the target will appear if it is a ballistic missile, then it is classified a false alarm and subsequently ignored by the Patriot.

In order to make this path calculation, the Patriot depends on its internal clock. Because the memory available to the program was limited, the clock value was truncated slightly when stored. By itself, this would not have been likely to cause significant errors; however, the Patriot's software was written so that the error compounded over time--the longer the Patriot was running, the larger the error became. Israeli military, analyzing data from Patriot batteries operating in Israel, were the first to discover the clock drift error. They calculated that after only 8 hours of continuous operation, the Patriot's stored clock value would be off by 0.0275 seconds, causing an error in range gate calculation of approximately 55 meters. At the time of the Dhahran attack, the Patriot battery in that area had been operating continuously for more than 100 hours--its stored clock value was 0.3433 seconds off, causing the range gate to be shifted 687 meters, a large enough distance that the Patriot was looking for the target in the wrong place. Consequently, the target did not appear where the Patriot incorrectly calculated it should. Therefore the Patriot classified the incoming Scud as a false alarm and ignored it--with disastrous results.
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http://shelley.toich.net/projects/CS201/patriot.html

The Patriot missile system had an abysmal success rating (about 10%-20%) in the first Gulf War. Most of what were seen on television as Patriot missiles blowing up Scuds were actually Patriot missiles that were intentionally destroyed because they had completely missed their targets--all due to poorly designed software coupled with using a system for something other than that for which it is was designed.
 
I am a little surprised nobody has proposed the obvious solution.

Speed up (or slow down if necessary) the rotation rate of the earth to keep it in sync with the atomic clocks. This will make everybody happy.

We can speed up the earth by dumping mountains into the ocean.

Probably some of you are thinking this is an impractical idea because what happens when we run out of mountains to dump into the ocean. Well at that point we might try nuclear bomb fueled rockets located at the equator to accelerate the earth.

Slowing down the earth is even easier. We can do it by building large wind farms or large dams to increase the friction from tidal forces.
 
Ah. So would another solution be to have every Chinese person jump up and down at exactly the same time?
 
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