Slashdot Mirror
US DoD Poll On Leap Seconds
@10u8 writes "For time scales to leap, or not to leap, has been the question here before. The ITU-R will be considering leap seconds again in a few weeks. This week the USNO posted a survey about leap seconds by the US DoD. The issue has civil implications as well as technical ones, and there is a demonstrated way to respect the history, remove leaps from navigation and POSIX time, yet keep the sun overhead at noon."
I thought we had leap years to take care of the discrepancy between our calendar and the actual orbit around the sun. Would a leap second even be made longer by any noticeable amount? What about sporting events? Someone who misses out on a world record by a tiny bit would complain that the record h older had more leap seconds in his race! (Okay, that one was a joke, but the rest I'm serious about)
Admit it. You post strawman arguments as AC so you get modded Insightful for refuting them, rather than Troll
No there isn't, but you can make it culminate at noon.
rj
I'd be more interested in killing Daylight Savings Time than dealing with Leap Year.
Currently hooked on AMP
Leap seconds correct for the rotation of the earth to keep the sun above at noon.
If we dispense with leap seconds then this relationship will slowly change and noon will eventually be dark.
Engineering is the art of compromise.
I'd be more interested in killing Daylight Savings Time than dealing with Leap Year.
My cat wakes me up in the morning. She doesn't adjust. Because of her, I'm a morning person. Unfortunately, 90% of society are night people. Meaning, any social activity is past my bedtime and I become a wet blanket because I start yawning at everything at 20:00.
This adding of leap seconds based on decisions by panels of experts or authoritative bodies is a nonsense.
If you're going to do this sort of thing - adding seconds to the clock here or there - it shouldn't be decided upon by some review committee. There should be a planned algorithm that kicks in, and the simplest one that actually does the job should be used. The bottom line is that a watch should be able to do it. If you do this, you're able to program devices to account for leap seconds instead of having to manually put in fudges which is an error prone process. You also get the possibility of adding leap milli-seconds or micro-seconds so fine grained adjustments are possible where required, whereas it would be much harder (though not impossible) to do that if you're manually correcting.
I'd be interested in hearing about specific instances where people work with equipment where this is a concern. I don't think I even own a time keep device where this level of accuracy matters. Perhaps my GPS???...
These posts express my own personal views, not those of my employer
We don't need even one more second of Bush presidency. :)
Yeah, I guess the clocks would have to take into account the increases in orbits and whatnot mentioned, but so what? Computation has become dirt cheap. So the Naval Observatory does an extra calculation for GPS and things that require that kind of accuracy.
And as far as I'm concerned, my clocks are all within 10 minutes of each other - in other words, I don't give a shit about 10 minutes either way.
Try not feeding her - I think you'll find she'll wake you up a lot earlier ...
-- Tigger warning: This post may contain tiggers! --
too lazy to deal with anything that even sounds like physical exertion unless they have a multi-million dollar contract.
rewriting history since 2109
You enjoy those 18-hour workdays, do you?
Keeping leap seconds synced is pretty important across comms networks.
Engineering is the art of compromise.
or that she won't wake you up at all!
"The fact that kdawson was able to read and understand this article..."
You must really be new around here.
and if anyone doesn't like leap seconds, all they have to do is use one of the time scales which don't use them, like TAI.
It's exceedingly silly and stupid for people to keep trying to change UTC so it doesn't track solar time. That what it was intended to do. If you made the wrong choice, live with it, or change time scales. If it's being forced on you, quityerbitchin', and convince whoever decided on UTC to change. Stop trying to turn UTC into something it isn't, there are other people out there who made an intelligent decision, and depend on it's characteristics.
"National Security is the chief cause of national insecurity." - Celine's First Law
So his opinion is wrong because it doesn't conform to the majority? I think you might be the one watching too much American Idol.
Changing the length of a second will end up changing almost everything in our lives. It would be an enormous undertaking, redefining, among many other things, electromagnetic wavelengths and the speed of light. Speed limits would change, computers would have to handle travel time calculations differently, and the length of the workday would change slightly.
It was hard enough to get the world to change to the metric system (with notable holdouts still remaining). Changing the very definition of one of the six core SI units would be nearly impossible.
You can never go home again... but I guess you can shop there.
Let's just remove the problem entirely!
I suggest... the French Republican calendar.
And a good Tridi, 23 Fructidor, Year 216 to you too.
"to leap or not to leap"
Time scales Prince Hamlet make.
proud caffeine whore
Why don't we just get Superman to fly around the Earth really fast to slightly change its rotation. If he can reverse time, surely he could adjust it sightly so that everything would work out.
I don't understand what the DoD has to do with time, standards or measurements.
Is the DoD trying to say now Muhahaha! Now we control time itself, submit all ye to "civilian time"?
We need to get the opinion of an expert, not some random poll.. perhaps the DoD should seek the advice of the master of timecube theory Dr. Gene Ray.
Bringing liberty to the masses. - http://freetalklive.com/
Who gives a damn about the sun being overhead at 12PM? China operates in a single timezone, despite spanning something like five, and they do just fine.
Give us GMT. Let noon drift where noon drifts. Just keep the seasons in line with the longest and shortest days and forget the rest.
I didn't mean to alter the actual measurement of time per se - e.g. as the world slows or speeds we adjust the length of a second.
What I meant was that, in actual fact, there should be leap nanoseconds and atomic clocks handle those adjustments, but we don't record them per se.
As to changing time, the Sumerians didn't even agree as to the precise definition, and many cultures have accurately kept time using wheels and water clocks using other measurements - China, Aztecs, Toltecs, etc.
We really only keep clock seconds - changing the names of the units above it shouldn't matter.
Besides, humans have a natural 25 hour clock, so it seems the earth may have rotated much faster originally, so our current "hours" are probably not correct.
-- Tigger warning: This post may contain tiggers! --
All time can be universal (UTC). Noon can be "When the sun is directly overhead." which will locally be different. Start time for work can be Noon-3 Hours (3 hours before noon) to Noon+5 Hours (5 Hours after noon). No DST necessary and no leap-seconds necessary. Why do they want to overcomplicate things here?
Reminds me of the Outer Limits show where the clocks were all adjusted to stretch the workday to be longer and longer while shortening off-work hours.
http://www.newearthcalendar.com/
13 Months of 28 days, with a leap week occasionally.
The problem is if you want weeks and months, there aren't many ways to split up the 365.24 days in a year.
Having a time notation that is based on fractional days would be cool, with .0 being midnight and .5 being noon would be nice.
If I have nothing to hide, don't search me
The problem isn't with UTC or TAI or any other timekeeping system used by the world.
The problem is with the cheap crap you have in your home which assumes every day is 86400 seconds long and every year is 365 days.
You bought it, you adjust it. I got better problems to solve.
It just shows that you don't understand the issue.
Over-the-top Response Guy! Giving "Over-the-Top Responses" since 1970.
No, it's what one of the Batman villains does in the bathroom. Also referred to as 'spouting a one-liner.'
The sun is directly overhead at 1 PM for most of the year due to Daylight Savings Time.
I'd like to just get it somewhere close and I don't much think a second or two is gonna help. I'm just outside of Chattanooga, TN at about longitude -84.90037 or physically at GMT -5.66 hours. [-84.90037 degrees / 15 degrees/hour ~= -5.66 hours ]. Legally, thanks to the idiots we elect to congress and the lobbyists who love them, my civil clock has to be set to GMT -4 for most of the year. In the cold of winter my sundial and the atomic clock only differ by about 40 minuets. The rest of the year the sun reaches zenith between 1:40 and 1:50. I can't bring myself to add post meridian to the time that the sun is actually at meridian. And 1:42 NOON just doesn't quit sound right either.
I think we should set aside leap seconds and make them the only time during the year that Congress is allowed to vote on anything that has to do with physical constants like time and distance.
Lets define the daily "work period" as: "three hours after sunrise to three hours before sunrise".
That's great, unless ya live in Barrow, Alaska...
Better have a caffeine stash ready by mid-June!
Don't tell me to get a life. I'm a gamer; I have LOTS of lives!
On a related note, I would have been all for the Swatch "Internet Time" deal, if they had actually made it useful by basing it off of GMT. But no, some marketdroids were all "let's base it off time in our headquarters in Switzerland!" So there wasn't much chance of anyone taking it seriously...
The World Wide Web is dying. Soon, we shall have only the Internet.
Leap Seconds
There aint no pancake so thin it doesn't have two sides.
What significance does this have for people who live in their parents' basement?
Have gnu, will travel.
Slightly offtopic, but does anyone know if the rotation of the earth around the sun mean that we actually rotate 366.25 times per revolution, or 364.25?
The ______ Agenda
http://en.wikipedia.org/wiki/Circadian_rhythm#The_myth_of_the_25-hour_day
Sam ty sig.
That sounds great, until you want to compute the DIFFERENCE in two times. How can you do that with any accuracy if you don't know how many leap nanoseconds have been inserted (because no record was kept) between them?
They did not ACCURATELY keep time by any stretch of the imagination. All those clocks you mentioned had to constantly be resynced with more authoritative sources on a constant basis - those authoritative sources being the position of the sun, moon, etc. Being able to create a device that could even take a stab at a unit of time as short as a second with any accuracy (if your second was 88,000 per day one day and 66,000 the next, it's not very useful!) had to wait until the invention of the pendulum clock in the late 1600's by Huygens. If by clock seconds, you mean track solar time, we have a clock that does that - it's called UT1. It can only be determined by measurement, so no devices that present a time readout independently use it. We instead keep UTC within a second of UT1 by inserting leap seconds from time to time.
Actually, the 25 hour circadian rythum argues for the Earth rotating SLOWER in the past, not faster - but, in fact, it did rotate FASTER in the past. Or, if you are a fan of intellegent creation or whatever it's called, when the Earth's rotation period slows to 25 hours (and presuming that an hour == 86,400 SI seconds) in however many millions of years, the time is right for ponies! Or something.
I've never managed to teach a cat to tell time, but I DID teach a cat to feed itself using an old Amiga 500, a custom feeding device connected via parallel (didn't NEED to be parallel, just that's what I wrote the software side as) and an oversized pad that technically was a 2 button mouse with no movement. If the large button on the left of the pad were pressed, a small amount of dry catfood would fall in to a bowl. If the button on the right were pressed, a small amount of water would fall in to a different bowl. I'd also occasionally buy soft food (fresh rabbit meat) as a special gift, but in general, he lived on the dry food and whatever he'd catch outside (birds, rats, baby possums etc). Once he got used to it, he never bugged me for food again.
Note: If you live somewhere where your cat can't hunt, this won't work without some modifications since cats need their soft/moist food as well as the dry stuff and that of course needs to be refrigerated.
It's also probably a no-go for your cat, since you said she's on a special diet.
My book about LSD and Self-Discovery
Also on facebook as: DroppingAcidDaleBewan
I've had a few different folks who worked on GPS over the years try to explain how it worked and it never made sense to me until just now. Maybe it's just because I drank a margarita but that explanation seemed particularly lucid. Thanks!
...my eyeballs dried up while I was reading the article. Is this possibly the most boring Slashdot story ever ?
Massive magma pumps are what's needed.
The Earth's getting a little ahead of time? Rotate the Earths surface a little by pumping magma in the earths core in the opposite direction.
Boffoonery - downloadable Comedy Benefit for Bletchley Park
I keep wondering, is linking /usr/share/zoneinfo/right to /etc/localtime enough to use TAI? The only problem with that is when I had to report a bug in an old version of Evolution, its calendar would do weird shit, like display the wrong day as "today."
At least that's what this guy does. I know, he's a pain the ass. You know, he's been right every time so far.
The right way to go about this is to use TAI for internal computations, and merely *display* UTC, so that when you want to measure the duration of an event, you just compute time_end-time_start. This does not work with UTC. Yet many brain dead systems do that, and apparently, if I'm not mistaken, every Linux distro.
It's on wiktionary, can't put it here thanks to slashdot's handling of unicode...
I can't touch that!
"When information is power, privacy is freedom" - Jah-Wren Ryel
when you are dealing with multi-year timespans where a second or two one way or the other can make a significant difference -- mainly astronomy, celestial mechanics, and satellite stuff.
Last time I had to deal with leap seconds in software, I found this: Sources for Time Zone and Daylight Saving Time Data which describes a system level time information database that includes leap seconds as well as Daylight Savings Time and time zones.
There are leap-second-aware time functions available that can be rolled into GNU C. Once they are in place, adding a leap second is a trivial sysadmin operation to update the time-info-database. Then all software using it will be correct without need to re-build or recompile.
... never to ask Slashdot "what time is it?" again.
'a';DROP TABLE users; SELECT * FROM DATA WHERE name LIKE '%'... if you're reading this, it didn't work.
..and we have a winner!
Bringing liberty to the masses. - http://freetalklive.com/