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Meet the Guy Whose Software Keeps the World's Digital Clocks In Sync (ieee.org)
New submitter Wave723 quotes a story on IEEE: In many cases, the internal clock that ticks away in a laptop or desktop computer is synchronized to an official time service maintained by the U.S. National Institute of Standards and Technology (NIST). This free service shares Coordinated Universal Time with personal devices, web browsers, financial trading software and e-mail programs throughout the world. The service receives 150,000 requests per second (roughly 16 billion a day) from systems that repeatedly ask, 'What time is it?' "If you have a PC, it's probably synchronized to the time service," says Judah Levine, the man who originally built servers and programmed software to send time over the Internet for NIST back in 1993.
Drink Coke! Or snort! Or shoot! JUST DO COKE!
Not from me it doesn't. I only ask maybe once a month.
“He’s not deformed, he’s just drunk!”
with my technology
A leap second is really no different from a leap day or the "extra" or "lost" hour due to daylight saving time.
I don't know why people have such a problem with it.
Count your ticks, determine how to show the date and time for a given locale.
Huh?
The Impact of Leap Seconds on Digital Time Services
Judah Levine
Time and Frequency Division
NIST, Boulder, Colorado
paper
Tweeeeet!!! 5 minute penalty for using the correct "whose"! Next time, use "who's" so you fit it with all the other geeks who are unable to understand the apostrophe!
TFA:
First of all, that's aspirational (or was) in most of the other articles I found.
Contra TFA: NIST Launches NIST-F2
Unfortunately, even contra TFA is weak geek tea:
I guess there's a reason why people with tiny UIDs memorize pi to a silly number of places: it helps you not leave off the other five or six significant digits in the rare case where it actually matters. The real frequency standard is only, like, approximately a million times better than that long-assed, dock-tailed string of digits visually implies.
Truly inconceivable—almost—and yet barely able to time slice the total perspective vortex.
Finally, some obligatory geek porn: Atomic fountain
and work a whole damn day
if you don't get your butt in gear
you won't get no more pay!
if this is supposed to be a new economy, how come they still want my old fashioned money?
Because the leap second like DST are _artificial_ and adds unnecessary complexity to an otherwise brain-dead simple algorithm. Complexity == Bugs.
The only one who gives a fuck about leap seconds are scientists.
Stop over-engineering a simple concept. Time should be monotonic, and consistent. Not this one-off shenanigans.
I no longer believe in time. I think it's pretty much junk science, and the daylight savings time thing is just an Illuminati plot to keep us subservient to the elite.
You all can do what you want, and spring forward or what not if you need to bend your will to The Man, but I ain't changed my clocks since 2007 and haven't noticed one thing. In fact, I couldn't change them since I threw out my wristwatch, Easy Rider-style, in 2006. Right now, if I look down at the time display on my screen, it's flashing 00:00:00, just like my DVD player and microwave.
You are welcome on my lawn.
I am using time.nrc.ca as my reference (I don't think it is a stratum 1 however)
"Science will win because it works." - Stephen Hawking
"What time is it?" 6 Billions times a day...
Sounds like a long road trip with my kids... Are we there yet, How much farther, When will we be there, What time is it
A powerpoint presentation is not a "paper." He publishes the leap-seconds.list file, which doesn't meet its own definition, which states "The first column shows an epoch as a number of seconds since 1 January 1900, 00:00:00". It doesn't do that, as it doesn't include leap seconds in that count (in a leap seconds file!!!). When asked about that error, he made the "leap seconds are forgotten" claim, which is ludicrous. He doesn't understand them, so wants to get rid of them because he doesn't understand how to deal with them.
"National Security is the chief cause of national insecurity." - Celine's First Law
Actually, the leap day is quite different than daylight savings time.
Usually, February has 28 days, except when it has 29 days. This is like a leap second, where once in a great while, a minute has 61 seconds.
daylight savings time doesn't inject any new time, it just retreads old time/skips time.
Practically speaking, a leap second would have been easier to model like daylight savings time (repeat one of the 60 seconds usually found in a minute), except that would mean some portion of indicated time would be ambiguous. That would have been perhaps aggravating for a whole day (two '28ths' of february would be pretty ambiguous for real-world concerns), but for a second it seems a bit more trouble than it's worth for all time systems to understand that there can be 61 second minutes...
XML is like violence. If it doesn't solve the problem, use more.
I thought trading system typically relied on GPS based NTP servers in their own network?
Oh and if you want to make your one: http://www.satsignal.eu/ntp/Ra... . While probably not as accurate as a commercial version, it is a tad slight cheaper.
Jumpstart the tartan drive.
He doesn't want to deal with them because in many cases time is best handled monotonically - ie, each second that passes simply counts as 1 second. For a variety of reasons slowing a clock to show the same :59 twice or slewing a clock so that :58, :59 :00 move slower, etc etc all cause lots of confusion. Simplest is to standardize on a time measurement that increases 1 unit per one second as an example, then if people want to format, and add confusion after the fact they can (DST, time zone, leap day, leap second etc). The underlying time measure just needs to move forward 1 unit of time at a time (an ordered sequence). This doesn't make him a nut.
Leap seconds aren't "artificial," any more than standard time zones are. They're directly related to the earth's natural rotation, as timekeeping has been for millennia. They are to the earth's rotation as leap days are to the earth's orbit. Additionally, time is monotonic, with or without leap seconds (or DST, for that matter, which merely involves a switch to a different timescale).
The biggest source of problems is POSIX, which some design-by-committee decided should define a day as having a fixed length, ignoring the existence leap seconds.
If you don't care about second accurate time, you don't have to deal with leap seconds, and your complexity problem is solved.
"National Security is the chief cause of national insecurity." - Celine's First Law
Leap seconds are a correction between the way that humans measure time and how the Earth spins
If this is not done, then there will be a difference between recorded and observed time
Accept it, or change the definition of a second, frankly leap seconds are easier
Monotonic, consistent times fail to meet human requirements, like times that match up with the solar day.
"daylight savings time doesn't inject any new time, it just retreads old time/skips time."
It doesn't even do that, it just switches between timescales. 3:59 EST = 4:49 EDT. The only thing the government mandated change does is define when the switch occurs. Informally, when someone states the time or sets their clock, they don't consider the xST/xDT part, so the change forward/backward appears to be a 1 hour change. DST doesn't make time discontinuous nor make in non-monotonic.
"National Security is the chief cause of national insecurity." - Celine's First Law
Does anybody really care?
#DeleteChrome
Unfortunately, Unix and NTP treat leap seconds completely different from Daylight Saving. They actually mess with the real measured clock, slowing it down. This is just completely broken of course, suddenly seconds aren't one second long any more. This has lead to system crashes and all sorts of fun.
There are two solutions to this: Either the NTP guys get their heads out of their asses, or leap seconds are abolished.
Unix is mostly ready, there can be 62 seconds in a minute in C, so all you do is switch the timezone files to the "right" directory instead of the "posix" directory (on GNU systems at least). But that cannot be done until NTP works.
Finally! A year of moderation! Ready for 2019?
The problem is there is a lot of time.
You may remember GMT, nowadays known as UT (not to be confused with UTC). GMT is time based on the Earth's rotation - when the sun is directly overhead, it's noon. There are approximately 86,400 seconds in a day here, but the mean solar day varies because Earth's rotation is not uniform. UT1 is the most common form of this, which is what time is measured at the prime meridian.
UTC is time derived from the atomic clock. It closely approximates UT, but since Earth's rotation is erratic, to keep the UTC day closely aligned with the UT day, leap seconds are sometimes added to ensure the difference between the two times is under 0.9 seconds.
TAI is the time as told by atomic clocks. Here, a day is exactly 86,400 seconds and there is no such thing as leap seconds - this is purely a monotonic clock that ticks away.
The problem is, well, there are a lot of variables. UT is measured generally once a day and clocks set to its time. UTC is a close approximation and generally used as it's easier to obtain without having to have someone observe the Sun every day to calculate when noon is. TAI is just the atomic clock time.
Leap seconds are introduced to keep UTC and UT relatively close to each other. TAI is allowed to drift, and eventually you'll have noon at midnight.
Which you pick is up to your needs. Leap years were created so people in the Northern hemisphere wouldn't be celebrating summer in December as the calendar drifts away from Earth's position in its orbit..
Then there's TAI, which is the true atomic time
The explanations in that file make it clear that the timestamps are given as NTP timestamps. Unix time and NTP do not count leap seconds. In Unix time and NTP, there are always exactly the same number of seconds from 23:59:30 to 00:00:30, whether a leap second was inserted between those times or not. The extra second is dealt with by stopping the clock for a second or running it slower so that it's back in sync with UTC after a few minutes. It would be a colossal misstatement to say that NTP timestamps represent seconds since a fixed point in time. This is acknowledged in the explanation that leap seconds shift the entire NTP timescale, including the epoch, by one second. NTP timestamps represent the number of seconds since the NTP epoch. The NTP epoch is not one point in time. It's as many non-leap seconds back in time as have occurred since 1990-01-01 00:00:00 UTC. It's off from that point in time by the number of leap seconds inserted since then.
Correction: 1900, not 1990. The NTP epoch is not 1900-01-01 00:00:00 UTC, it is as many seconds back in time as non-leap seconds have occurred since 1900-01-01 00:00:00 UTC.
Biggest problem is that there can't be anything but 86400 seconds in a POSIX day _and_ it enumerates time as seconds since 1/1/70, two things which are mutually exclusive. "Right" time fixes some things, but can break stuff which expects POSIX time.
But yes, ntpd (the reference implementation) is very broken - it doesn't even follow its own RFC with regard to enumerating time. Of course, anyone who is inclined to produce a correct implementation will bump into the fact that the reference implementation is spewing incorrect timestamps everywhere, and systems expect that. It was developed to keep POSIX time, so just like POSIX, doesn't deal well with leap seconds or UTC.
"National Security is the chief cause of national insecurity." - Celine's First Law
time zones are artificial, they reflect political borders. And nothing is more artificial than politics.
“Common sense is not so common.” — Voltaire
Except I can accurately predict centuries in advance when February 29 occurs.
Leap seconds are added whenever measurements cause a committee at the UN non-governmental organization that oversees the standard (International Earth Rotation and Reference Systems Service) to schedule for a leap second to be inserted.
“Common sense is not so common.” — Voltaire
Standard timezones were introduced as a practical convenience, so people in close proximity could share common (standard) time, as opposed to every town having their own 12:00 high noon. But, the timezone itself was still locked naturally to Sol, only the borders were artificial/political. Similarly, the leap second allows clocks worldwide to tick simultaneously based on an artificial human definition of the second, which was previously 1/86400 of a solar day. Leap seconds exist because the second itself is now an artificial construct, and they're needed to stay in sync with nature.
"National Security is the chief cause of national insecurity." - Celine's First Law
They actually are very difference from daylight saving time. Daylight saving time is an offset against UTC. Leap seconds actually change UTC. Another difference is a leap second is applied to all timezones at the same time, while a leap day is only applied relative to each time zone. You also have the issue that a leap day is a change to a date while a leap second is a change to a time. It's hard to tell the difference between two clocks being 1 second off and not knowing which one is correct, but it is very easy to tell when a clock is a day off.
my pc's clock is off by an hour.. can you fix that please? and while you're at it, can you also fix the phone, dvr (and associated network schedules), and car, too?
Judah Levine, the gentleman mentioned in the article, built interfaces to existing atomic clocks that allowed other clocks to synchronize with them, which is a worthy achievement.
But today, the vast majority of synchronized clocks are being kept synced by NTP across the Internet, not by radio signals. And although Levine also implemented NTP interfaces at NIST, he didn't invent NTP nor was he responsible for its dominance of Internet timekeeping.
The man who invented NTP and originally wrote the implementation was David L. Mills of the University of Delaware.
Mills is also the man who created the Fuzzballs and EGP, making global-scale internetworking possible.
Except NTP does the exact opposite: It doesn't "count" leap seconds. It leaves the conversion between NTP timestamps (seconds since the NTP epoch) and UTC timestamps (seconds since the UTC epoch) to the application. Every time a leap second is added to UTC, NTP switches to a new NTP epoch: The NTP timestamp 2272061000 marks the point in time that was 2272061000 seconds after 1900-01-01 00:00:10 UTC, which was the NTP epoch at that timestamp. That timestamp was 2272061010 seconds after 1900-01-01 00:00:00 UTC, which one might naively but incorrectly consider the NTP epoch. Currently, the actual NTP epoch is 1990-01-01 00:00:36 UTC.
Damnit, 1900, not 1990. I did it again.
There's a lot of false assumptions being made in this thread. Humans introduced this craziness of leap seconds in an effort to more accurately understand time. We made a big mistake last time we tried to recalibrate which no has us doing this leap second dance. This video clearly explains the Leap Second: https://www.youtube.com/watch?v=RuPQsqZaq8A
Timezones are artificial no matter the justification. If we are keeping time by the sun, driving 1 hour in either direction would cause the time to change, even if only by seconds or minutes. Instead, it doesn't change until you reach some magical boundary (and I'm not even talking about timezones that skirt around political borders, I'm talking about longitudinal hour markers). And it is magical because it is compressing all the other longitudes into just that one.
Time itself is an illusion. Lunchtime doubly so.
I think I saw that in Reader's Digest.
I like one of the ideas someone had when adding a leap second.
The second count in time_t stays the same one second longer.
But in struct timeval the tv_usec keeps counting beyond 999; till 1999.
> Leap years were created so people in the Northern hemisphere wouldn't be celebrating summer in December as the calendar drifts away from Earth's position in its orbit..
First World Problems. Someone call the wambulance.
Just use TAI where no fucking hacks are needed, and get rid of this retarded leap second, leap year, and DST.
Goatse Guy looks like the accountant next door compared to rosebudding...
Long before we start having winter in July on the northern hemisphere we will start to have to shift store opening hours since 12:00 isn't noon anymore. Given that we want business hours to coincide with daylight this would be a much bigger problem long before we have snow in July. And who cares what season is in what month. That is totally irrelevant. There are places, like Aruba, where there are no discernable seasons. Do they only have June because of this?
TAI is good for scientific purposes, but leap days, leap seconds and timezones are good for human society, as biological creatures dependent on sunlight we should adjust our timekeeping for the light. DST on the other hand is pointless. The places that need it the most, close to the poles, are the places where the difference due to adjustment disappears quickest. In just a few weeks the adjustment for DST has gone away due to the rapidly increase/decrease in lenght in daylight.
That's from the Hitchhiker's Guide to the Galaxy. Hand in your geek card.
I'm not into time...
Timezones are a best practice solution to a difficult paradox.
1) Noon is when the sun it highest in the sky
2) If it is Noon here, it should be Noon nearby
3) If it is Noon here, it is Midnight on the other side of the world
Obviously, once that third item was discovered, we needed a solution. One that gave each longitude its own time zone to the minute would have been 'more correct', but much more confusing as then there would be 1440 timezones, which would be hard to keep track of now, much less over a century ago. So they broke the earth into 24 timezones that all had the same minutes, and only differed by hours. Naturally, the boundaries have evolved politically, but the concept itself is sound.
The universe has as much need to coordinate Earth's rotation with the flatulence pulses of the bombardier beetle, as it has to coordinate $ThisLunarSolarEclipse$ with $ThatEuropaIoMutualEclipse$. I.e. none at all.
This sort of adjustment is only an issue if you do it very rarely. If you deal with events more than a coupple of hours different from your local sun rise/set, on a regular basis, you don't find this a proble. You just put several clocks on your wall, with BIG SIGNs on th wall.
Birds are not dinosaur descendants;birds are dinosaurs, for all useful meanings of "birds", "are" and "dinosaurs"