ygslash writes "The IERS has announced today that, after seven years, there will once again be a leap second this year. On December 31, 2005, the time 12:59 will last for 61 seconds."
The only problem is that no one knows how its supposed to work.
They work much like warp speed - start out low and end high. The higher the epsiode number, the higher the range. I think that it's derived from fishing, where "the big one that got away" gets bigger each time the story is told.
Actually, and it's been a long time for me here, but I think Warp 1 = speed of light and the other warps went up from that exponentially. So warp 9.9 wasn't 9.9 times faster than the speed of light. It was many many many times greater than that...which is how they were able to zip around from one end of the quadrant to the other in a manner of days.
And of course, they explained away relativity effects because they were in a "warp bubble" when at warp speed...that is if they weren't trapped on the Holodeck
Note: Under the old system (used in the Original Series,) devised by Zephram Cochrane, the speed at any warp factor was given as: Ship's Velocity diveded by C is equal to the Warp Factor Cubed.
Therefore, in the Original Series, a Warp Factor of 3 was 27 times the speed of light, while a Warp Factor of 14 ws 2744 times the speed of light, or between Warp 9.6 and 9.9. I do not have the forumala for determining Warp Factors for the system, nor for the new system above 9. (They are the same formula, though
Its always bugged me how in a leap year, we have an extra day... but a leap second is an entire extra second... if the terminology were consistent, that would mean a leap yer would equal one extra year.. or that a leap second was some fraction of a second longer than a normal one.
"To authorities responsible for the measurement and distribution of time..." How do I make an official complaint with these time-distributing authorities for all the times I've been blamed for being late? Everyone always thought it was my fault for running out of time--but nope, turns out there are "authorities" in charge of all that. Are they any relation to the Tooth Fairy?
Isn't this sort of thing calculable farther in advance? There shouldn't be a whole lot of angular momentum being added or subtracted from the Earth's rotation.
Do I need a new glibc? Or any other POSIX library, for that matter? If this is a new announcement then presumably every implementation of mktime(), localtime(), gmtime(), etc. needs to be updated.
Actually you'd just set the NTP server you're syncing with one second ahead. I don't think that a once-every-seven-year event is going to be worthy of kernel changes, especially since your time is probably off by more than one second as it is.
Actually you'd just set the NTP server you're syncing with one second ahead.
That simple solution will cause one of two problems: either your time will be off by one second, or the calculation of the number of seconds between two events crossing the leap second will be off by one second.
I don't think that a once-every-seven-year event is going to be worthy of kernel changes, especially since your time is probably off by more than one second as it is.
If you're regularly using NTPD your time is probably
Sounds like a software issue, not a hardware one. If your clock consistently needs to be adjusted by 0.31xxx seconds, then ntpd should be automatically adjusting by 0.31 seconds every 4 hours. ntpd will do this if it is run in daemon mode.
Actually, it's not calculable farther in advance. The Earth's rotation is inconsistent enough that leap seconds are sometimes needed, but the need can't be predicted more than about a year in advance [1]. In other words, there is noise in the Earth's rotation period of about 1 second per year. Atomic clocks are a lot better than this (good to ~50 ns per year [2]!!!), so it's pretty easy to detect the problem.
According to a link I just read, POSIX doesn't handle leap seconds [cr.yp.to]. So yes, if you use NTP, like someone else suggested, your time will be correct, but any measurements of time crossing leap seconds won't.
The correct solution in my opinion would be to store leap seconds along with the timezone information. That's really what they are. Unix time could be stored in TAI instead of UTC, and thus subtracting two times from each other would still give the correct result.
Well, regarding the second point, think of this as a reminder of why you should NEVER EVER store future time and date values as offsets from an epoch time/date, if being one second off is bad for your application.
Seriously, you'd think they'd pick a less conspicuous second to make the switch. Instead they picked the one second of the year that people notice more than any other. At least it'll only affect the New Year's count for the Brits. Here in the US we won't even be heading to the party yet.
Microsoft has $33.8 billion in short term investments. Since interest payments are calculated by the day, and not the second, at an interest rate of 3% Microsoft will lose $1929 in interest due to this leap second.
The thing that bothers me is, when that big quake in Indonesia went off last year and caused that big tsunami, they talked about how the Earth's rotation SPEEDED UP. If it has already slowed down again in only one year, such that a leap second is needed, then that implies some other place has been bulging and may be about to give way. So, any Slashdotters who can pass this inference on to the geology folks, please do so pronto! Thanks!
I have calculated[1] that in 1000 years a leap second will be required about every two months. It's likely that at that time we would still be using time standards similar to those in use now.
On the other hand, in 1 million years, about 15 leap seconds will be required each day. Therefore, at some point timekeeping must necessarily divide the day into units that are not an integral number of seconds. We would have a situation where the record for the 100 metres dash is expressed in seconds, but the length of the second used for dividing up the day is not the same length. Such "stretched time" has already been used for the Spirit and Opportunity rovers on Mars.
[1] A common formula for approximating the evolution of delta-T over time is 31 * Cy^2, where Cy is expressed in centuries.
Not so many centuries ago, the concept of 'hour' was flexible, depending on the season. 12 day hours, 12 night hours, regardless of the ratio between them. Back to the old?
The same uber-nerds who defined the meter have also defined the second.
Lifted from wikipedia - The second is one of seven SI base units. It is defined as the duration of 9,192,631,770 periods of the radiation corresponding to the transition between the two hyperfine levels of the ground state of the caesium-133 atom at zero kelvins.
Now that we have a definition perhaps someone could tell us what it means.:)
All it means is that someone looked at the conventional length of a second (1/86400 of a day) and found a natural phenomena that was really, really, really, really, really close, and unlike the length of a day, won't change over time.
As another example, take the metre. You can see how the definition of the metre became more and more precise here [wikipedia.org]. I don't see it mentioned there, but the original "meaningful" definition of the metre, if extremely imprecise, is based on water: 1 ml of water = 1 gm in mass =
The second is one of seven SI base units. It is defined as the duration of 9,192,631,770 periods of the radiation corresponding to the transition between the two hyperfine levels of the ground state of the caesium-133 atom at zero kelvins.
The definition is made in terms of the most accurate way we have of measuring it - with the atomic clock. There's a description of how they work here [howstuffworks.com].
In the future the definition may change - there are developments to produce "optical clocks" which are more accurate
I have calculated[1] that in 1000 years a leap second will be required about every two months. It's likely that at that time we would still be using time standards similar to those in use now.
Simple solution, change the 60 Hz power line frequency to 59.9999885922 Hz, causing power-line synchronous clocks to slow down to match the daily rotation of the Earth (as referenced to the Sun).
On the other hand, in 1 million years, about 15 leap seconds will be required each day.
A common formula for approximating the evolution of delta-T over time is 31 * Cy^2, where Cy is expressed in centuries.
The formulae are to some extent empirical as well as being approximations. The evolution of delta-t is also extremely 'noisy', and is far from a good fit with any of the formulae [phys.uu.nl].
For the last few years it's been at around 64 seconds (see data in here [navy.mil]), which comes to about 3 or 4 seconds less for the present time than some recent formulae were predicting even only a few years ago, and l
Oh the opportunity! (Score:4, Funny)
Re:Oh the opportunity! (Score:2)
Star Trek has it figured out. (Score:4, Funny)
The only problem is that no one knows how its supposed to work.
Re:Star Trek has it figured out. (Score:5, Interesting)
They work much like warp speed - start out low and end high. The higher the epsiode number, the higher the range. I think that it's derived from fishing, where "the big one that got away" gets bigger each time the story is told.
Parent
Re:Relativity (Score:2)
Re:Relativity (Score:2)
And of course, they explained away relativity effects because they were in a "warp bubble" when at warp speed...that is if they weren't trapped on the Holodeck
Re:Relativity (Score:2)
From the Star Trek Encyclopedia:
Note: New Cruising Speed
Note: Old Cruising Speed
Note: Old Normal Maximum Speed
Maximum rated Speed, can be maintained for 12 hours
Auto-shutdown of engines after 1
Re:Relativity (Score:2)
Note: Under the old system (used in the Original Series,) devised by Zephram Cochrane, the speed at any warp factor was given as: Ship's Velocity diveded by C is equal to the Warp Factor Cubed.
Therefore, in the Original Series, a Warp Factor of 3 was 27 times the speed of light, while a Warp Factor of 14 ws 2744 times the speed of light, or between Warp 9.6 and 9.9. I do not have the forumala for determining Warp Factors for the system, nor for the new system above 9. (They are the same formula, though
Shouldn't that be... (Score:2)
Re:Shouldn't that be... (Score:5, Informative)
The sequence of dates of the UTC second markers will be:
2005 December 31, 23h 59m 59s
2005 December 31, 23h 59m 60s
2006 January 1, 0h 0m 0s
Actually, its 12:00:00 then another 12:00:00.
Parent
Re:Shouldn't that be... (Score:2)
Good thing neither the editors or news submitters can tell time properly! (23h 59m 59s = 11:59:59 PM, 0h 0m 0s = 12:00:00 AM)
Re:Shouldn't that be... (Score:3, Informative)
0h 0m 0s = Midnight
12h 0m 0s = Noon.
These is no such time as 12:00:00am (or 12:00:00pm).
See NIST [nist.gov] for the gory details.
Re:Shouldn't that be... (Score:2)
Yay! (Score:3, Funny)
Its always bugged me how... (Score:3, Interesting)
Re:Its always bugged me how... (Score:2)
Re:Its always bugged me how... (Score:2)
Re:Its always bugged me how... (Score:2)
Tire Rotation (Score:2, Funny)
Welcome to the International Earth Rotation and Reference Systems Service
Will they change my oil and check my brakes, too?
I knew it! (Score:3, Funny)
Two questions (Score:3, Insightful)
Do I need a new glibc? Or any other POSIX library, for that matter? If this is a new announcement then presumably every implementation of mktime(), localtime(), gmtime(), etc. needs to be updated.
Re:Two questions (Score:3, Insightful)
Re:Two questions (Score:2)
Actually you'd just set the NTP server you're syncing with one second ahead.
That simple solution will cause one of two problems: either your time will be off by one second, or the calculation of the number of seconds between two events crossing the leap second will be off by one second.
I don't think that a once-every-seven-year event is going to be worthy of kernel changes, especially since your time is probably off by more than one second as it is.
If you're regularly using NTPD your time is probably
Re:Two questions (Score:2)
Re:Two questions (Score:5, Informative)
Actually, it's not calculable farther in advance. The Earth's rotation is inconsistent enough that leap seconds are sometimes needed, but the need can't be predicted more than about a year in advance [1]. In other words, there is noise in the Earth's rotation period of about 1 second per year. Atomic clocks are a lot better than this (good to ~50 ns per year [2]!!!), so it's pretty easy to detect the problem.
Sorry, I can't help with the second question.
[1] See this Wikipedia article [wikipedia.org].
[2] See this Wikipedia figure [wikipedia.org].
Parent
Re:Two questions (Score:3, Informative)
According to a link I just read, POSIX doesn't handle leap seconds [cr.yp.to]. So yes, if you use NTP, like someone else suggested, your time will be correct, but any measurements of time crossing leap seconds won't.
The correct solution in my opinion would be to store leap seconds along with the timezone information. That's really what they are. Unix time could be stored in TAI instead of UTC, and thus subtracting two times from each other would still give the correct result.
Whenever a leap second was announced y
Re:Two questions (Score:2)
Off by one error (Score:4, Interesting)
Re:Off by one error (Score:2)
NINE!
EIGHT!
SEVEN!
SIX!
FIVE!
FOUR!
TWO!
ONE!
ONE!
HAPPY NEW YEAR!
lameness filter encountered reason: don't use so many caps. it's like yelling.
-
Re:Off by one error (Score:4, Insightful)
Parent
Ugh! (Score:2, Funny)
12:59 AM or PM? (Score:3, Informative)
leapsecond.com (Score:4, Informative)
Okay, here's a clickable link:
http://leapsecond.com/ [leapsecond.com]
An obsession in another are of time is this Y10K Compliant clock:
http://longnow.org/ [longnow.org]
Bad for Microsoft (Score:4, Funny)
Re:These guys must not be real nerds (Score:2)
Re:These guys must not be real nerds (Score:3, Funny)
Re:These guys must not be real nerds (Score:5, Interesting)
Parent
Re:These guys must not be real nerds (Score:2)
so 41 not divisible by 3
19 * 42 = 798
41 * 69 = 2829
------------------
3627 seconds / hour
60.45 minutes / hour
Nope, not perfect. Means I have to work an extra 3.6 minutes / day.
Re:Should we really bother? (Score:5, Interesting)
I have calculated[1] that in 1000 years a leap second will be required about every two months. It's likely that at that time we would still be using time standards similar to those in use now.
On the other hand, in 1 million years, about 15 leap seconds will be required each day. Therefore, at some point timekeeping must necessarily divide the day into units that are not an integral number of seconds. We would have a situation where the record for the 100 metres dash is expressed in seconds, but the length of the second used for dividing up the day is not the same length. Such "stretched time" has already been used for the Spirit and Opportunity rovers on Mars.
[1] A common formula for approximating the evolution of delta-T over time is 31 * Cy^2, where Cy is expressed in centuries.
Parent
Re:Should we really bother? (Score:3, Interesting)
Re:Should we really bother? (Score:2)
A standardized second. (Score:3, Funny)
Lifted from wikipedia - The second is one of seven SI base units. It is defined as the duration of 9,192,631,770 periods of the radiation corresponding to the transition between the two hyperfine levels of the ground state of the caesium-133 atom at zero kelvins.
Now that we have a definition perhaps someone could tell us what it means.
Re:A standardized second. (Score:2, Informative)
As another example, take the metre. You can see how the definition of the metre became more and more precise here [wikipedia.org]. I don't see it mentioned there, but the original "meaningful" definition of the metre, if extremely imprecise, is based on water: 1 ml of water = 1 gm in mass =
Re:A standardized second. (Score:2)
Re:A standardized second. (Score:2)
The definition is made in terms of the most accurate way we have of measuring it - with the atomic clock. There's a description of how they work here [howstuffworks.com].
In the future the definition may change - there are developments to produce "optical clocks" which are more accurate
Re:Should we really bother? (Score:3, Interesting)
Simple solution, change the 60 Hz power line frequency to 59.9999885922 Hz, causing power-line synchronous clocks to slow down to match the daily rotation of the Earth (as referenced to the Sun).
On the other hand, in 1 million years, about 15 leap seconds will be required each day.
Simple solution, change the 59.9
Re:Should we really bother? (Score:2)
The formulae are to some extent empirical as well as being approximations. The evolution of delta-t is also extremely 'noisy', and is far from a good fit with any of the formulae [phys.uu.nl].
For the last few years it's been at around 64 seconds (see data in here [navy.mil]), which comes to about 3 or 4 seconds less for the present time than some recent formulae were predicting even only a few years ago, and l
Re:I have an atomic watch! (Score:2, Funny)
Re:I have an atomic watch! (Score:3, Informative)
Re:How will GPS be affected? (Score:2)