Slashdot is powered by your submissions, so send in your scoop

 


Forgot your password?
Close
typodupeerror
×
Technology Science

Atomic Clock Turns 50 482

Posted by Zonk from the happy-birthday dept.
karvind writes "BBC has an interesting story on the 50th birthday of atomic clocks. The first accurate caesium atomic clock was developed at the NPL in 1955 by Dr Louis Essen. And after 5 decades In September the US National Institute of Standards and Technology (NIST) used computer chip fabrication techniques to make a small atomic clock. The final development should see a battery-operated system about the size of a sugar lump. NIST also has a page on history of atomic clocks"
This discussion has been archived. No new comments can be posted.

Atomic Clock Turns 50 More

Atomic Clock Turns 50

Comments Filter:

  • Yeah... (Score:3, Funny)

    by eurleif ( 613257 ) on Saturday June 04, 2005 @07:33PM (#12726393)
    It's a good thing we had atomic clocks so we could be sure it was really 50 years!

  • A beryllium atomic clock...just what the Doctor ordered!

    Jelly baby?

    ^_^

  • Units of measure (Score:4, Funny)

    by Kirkoff ( 143587 ) on Saturday June 04, 2005 @07:34PM (#12726398)
    Lump of sugar has to be the oddest comparison ever...

  • Time (Score:4, Funny)

    by maelstrom ( 638 ) on Saturday June 04, 2005 @07:36PM (#12726410) Homepage Journal
    I used to be obsessed with accurate clocks, still am for my servers, but after awhile its all relative anyway ;)

    • Re:Time (Score:2, Interesting)

      by AndroidCat ( 229562 )
      I used to tune in a shortwave time-signal station like WWV or CHU to carefully set my computers. Now, with Internet, they just automatically join the DDoS against TL time servers once a week.
      • "Now, with Internet, they just automatically join the DDoS against TL time servers once a week."

        Oh but the burning question. time.windows.com or time.nist.com?? One for accuracy and one for spite in an attempt to rob MS of bandwidth. Choose wisely.
      • There is a project to serve NTP round-robin from a number of servers. You can use this pool thusly with ntpd:

        server pool.ntp.org

        If you live in Canada or the US you can even do:

        server north-america.pool.ntp.org

        Read more at:

        http://www.pool.ntp.org/ [ntp.org]

  • Actually...... (Score:3, Funny)

    by LiquidCoooled ( 634315 ) on Saturday June 04, 2005 @07:38PM (#12726427) Homepage Journal
    The atomic clock turned 49.9999999999999999999999 today!

    Congratulations ;)

  • Lots depend on the clock now (Score:5, Informative)

    by esconsult1 ( 203878 ) * on Saturday June 04, 2005 @07:38PM (#12726432) Homepage Journal
    Official US time Clock [time.gov]

    It seems that more and more of everything is sync'd with this. My clock radio at home auto-updates, clock on the wall, the cellphones, my Linux and Mac PC's and cable box.

    Only thing left are the clocks with a single AA battery on the wall, and at some point they are going to use the pervasive WWVB time signal [ntp-time-server.com] that is broadcast from Colorado and operated by the National Institute of Standards and Technology [nist.gov]

    This technology has really come a long way and is deeply embedded within our lives. Especially if you consider that before the atomic clock, time varied considerably between different locales.

    • Don't forget GPS... to measure distances with radio signals travelling at the speed of light, you need to have very accurate clocks [wikipedia.org] to do the speed * time = distance calculations. Even the cheapest GPS unit is very very accurate, in that it directly syncronizes with the GPS atomic clocks.

    • Don't forget banks...today's banks calculate interest down to fractions of a second.
    • OTOH I recently took a bit of a vacation. There were no clock radios, linux boxes, or PDA's involved. Let alone networked ones which can get the current time. Ya know what? The Sun, Moon, and Earth still revolved and rotated on their scheculed path. The rest of the galaxy did the clockwork thing. And I didn't worry about any of it. Yeah, there is a time and a place (and I used to use both WWV and DeutscheWelle), and things have come a long ways. But I doubt that changing the way we measure things is goin
    • Super accurate time-keeping is also a critical aspect of the cellular telephone network. In fact, the time you see displayed on many/most cellphones quite likely originated from the GPS sats.

      One can buy a rackmount device which pulls GPS-origin'd time from the CDMA phone signals - see e.g. time.twc.weather.com (a publically accessible NTP server) which has such a device attached.

    • Re:Lots depend on the clock now (Score:4, Interesting)

      by Tim Browse ( 9263 ) on Sunday June 05, 2005 @05:35AM (#12728264)
      Only thing left are the clocks with a single AA battery on the wall, and at some point they are going to use the pervasive

      Dude, that's so 5 years ago. I just bought a wall clock [argos.co.uk] for my kitchen that takes an AA battery, and it syncs to the UK nuclear clock signal. It's great.

      Cost? 8 pounds.

      A similar clock in my living room does the same thing. The futar is here!

      • Dude, that's so 5 years ago. I just bought a wall clock for my kitchen that takes an AA battery, and it syncs to the UK nuclear clock signal. It's great.

        Cost? 8 pounds.

        You don't know the Cost but it weighs 8lbs. Kinda heavy for a clock.
  • and we still don't have time travel. What a shame.

  • They got it all wrong! (Score:5, Funny)

    by Psionicist ( 561330 ) on Saturday June 04, 2005 @07:39PM (#12726436)
    That article is not precise! The atomic clock is 50.00000100121412235901293409234 years old as I'm writing this.
  • ...atomic clocks are old enough to get classified as antiques & collectibles. Kids with ultra-wristwatches that tell your exact location by relativity effect at walking speed will laugh and laugh. You will be able to by them as cheap gifts for little kids at the $2,000,000,000,000 shop without a second thought.

    • Re:It'll be interesting when.... (Score:4, Interesting)

      by CastrTroy ( 595695 ) on Saturday June 04, 2005 @07:47PM (#12726479)
      There really is no market for atomic clocks. At best you will get devices that sync themselves to an atomic clock, that's located far away. Even people that do have pretty accurate clocks are always late. I find that in general, most people are late, and don't really worry too much about time in the first place. Really gets on my nerves, as i'm always on time, and always have to wait for someone.
      • Yeah, as I was writing I was thinking you would still be late for work no matter what. Heh heh. Seeing time is not constant everywhere, atomic clocks are going to get out of sync. Nobody would be right. What's all this UCT (Universal Co-ordinated Time) stuff? No such thing really ;-)
        • I believe time travels slower at the equator than at the polls. It's only changes the point of a second in a long time, but it's not nearly 20 million years, so what's the point of having clocks that accurate to brodcast across multiple lattitudes?

          • Re:It'll be interesting when.... (Score:5, Funny)

            by Webmoth ( 75878 ) on Saturday June 04, 2005 @10:46PM (#12727167) Homepage
            "I believe time travels slower at the equator than at the polls."

            I don't know about that. When I was standing in line at the polls back in November, time seemed to drag on. Now, afterwards, it's dragging on even longer while we here in Washington State are still wondering who our governor is.

            What's that? You meant poles? My mistake.
      • There is still a market for atomic clocks. An atomic clock provides two services, the current time and an extremely stable and accurate oscillator. Many applications, like the telephone system, may not care about the current time, but they need very high quality frequency standards to keep the network synchronized. Even if periodically synchronized to a remote atomic clock, the quality of the time provided by a local clock is heavily dependent on the stability of its oscillator.
  • thank you for ore abilty to micro manage our lves
  • How the hell do the British see see-zee-umm in that? Tsai-sai-umm?
    • Same way they see pronounce, Caesar. Like the salad, or the roman guy. Anyway, here's a good one for you. Aluminium. Think about that one for a while. It's actually pronounced how it's spelled.
    • The vowel ae - it should be æ - is the same as in the word encyclopædia and Cæsar. I've never heard it pronounced as anything else but as a long 'e'.

      Of course, to be sure, a Latin professor would have to tell us how to pronounce caesius, (light blue), as that's the origin of the name.

      Lastly, the spelling cesium is reluctanly accepted as a US spelling.

  • can you recall the scene ... (Score:4, Funny)

    by Anonymous Coward on Saturday June 04, 2005 @07:46PM (#12726470)
    Four scientists, as they flip the switch on their new invention ...

    #1: Gee, Ed, it looks like it works ...
    #2: Bob, you're right! It's counting! We did it!
    #1: It seems to be right on, let's fire up the chronotaph ...
    #3: Already there, Bob, I have a solid register, five-nines. I started the paper before you hit the button.
    #1: Good thinking, Stan. This is one for the record books!
    #2: This is a clock for your ass, Ed! I guess we should set it now.
    #4: Okay guys (looks at watch) what have you got? I'm showing a quarter past two.
  • From TFA:

    "As net data is split in data streams and reassembled, for instance, the timing has to correct at the point of re-assembly.

    If not, whatever data has been sent - voice packets in VoIP net phone calls for example - will come out garbled.    "

    Did anyone else laugh as they read this? The writer of this article is unaware of sequence numbers... (and thinks that a timestamp is placed on each packet instead.) Wow. But this could also work with the computer's internal clock... though then all routing de

    • Re:Net data? (Score:4, Interesting)

      by pyrrhonist ( 701154 ) on Saturday June 04, 2005 @11:45PM (#12727326)
      Did anyone else laugh as they read this? The writer of this article is unaware of sequence numbers... (and thinks that a timestamp is placed on each packet instead.)

      No, because he's essentially correct.

      In VoIP protocols, a timestamp *is* placed in every packet along with a sequence number. The timestamp is used to place the incoming audio and video packets in the correct order with regard to time. The sequence number is used to detect packet loss. So basically, sequence numbers don't help you with jitter. The timestamp is use to actually calculate the amount of jitter, so it's rather important for it to be as accurate as possible.

  • Now we should all thank Dave Mills... (Score:3, Funny)

    by e9th ( 652576 ) <e9th@NoSPAm.tupodex.com> on Saturday June 04, 2005 @07:49PM (#12726486)
    because without NTP, we might as well be using sundials.
  • ...if nobody was actually measuring the time? I say zero and fifty years concurrently.
  • This is a question that must get asked a lot, and I wasn't able to find an answer (casually searching) on the gov website.

    How did they figure out how to set the clock initially? Thanks.

    • Re:Setting the clock initially (Score:5, Informative)

      by Smidge204 ( 605297 ) on Saturday June 04, 2005 @08:29PM (#12726640) Journal
      That's like asking how does the "clock" in your computer get set to the right time. (Not the system clock, the crystal that generates the clock frequency the electronics operate off of).

      Atomic clocks just "tick", not display an actual time. They provide an extremely reliable and high frequency tick which makes them so valuable.
      =Smidge=
    • The atomic clock is not an absolute timekeeping device.
      It is simply a very accurate counter.

      Your question remains valid, and I have just wasted 23.3945738453784578346578345 seconds pondering and writing this post.
    • They probably used whatever was the most accurate clock at the time. It doesn't really matter. Better clocks allow you to measure time intervals more accurately, they don't help much with absolute time. Absolute time is just an artifact that is defined by committee.

    • Re:Setting the clock initially (Score:4, Informative)

      by prodangle ( 552537 ) <matheson@@@gmail...com> on Saturday June 04, 2005 @09:53PM (#12726972) Homepage Journal
      How did they figure out how to set the clock initially? Thanks.

      Atomic clocks count the number of vibrations within an atom, so know how much time has passed to a high degree of accuracy. Absolute time however, cannot really be known, as we have no reference point to measure it from (unless we find someone who has been counting since the big bang happened!).

      The standard day-to-day time system is UTC [beaglesoft.com] (rather mysteriously standing for Coordinated Universal Time) and it is based on the rotation of the earth. This is decided by the BIPM [bipm.org]. As the length of a day is not precisely divisible by a second, leap seconds [beaglesoft.com] occasioanlly have to be added.

      • The standard day-to-day time system is UTC (rather mysteriously standing for Coordinated Universal Time) and it is based on the rotation of the earth. This is decided by the BIPM. As the length of a day is not precisely divisible by a second, leap seconds occasioanlly have to be added.

        The Big International Scientific Conference that got together to define a new time scale to replace GMT had no difficulty coming up with the name "Coordinated Universal Time", but deadlocked when it came time to decide

    • Ok, there are two issues with clocks. The first is the length of certain interval of time, the other is exactly how we communicate that it is a certain time of day.

      Atomic clocks were primarily developed to deal with former, measuring the passage of time. This turns out to be a very important and difficult problem in all fields of science and engineering. The reason is that any error is measureing the passing of time will be amplified and make all other things very wrong.

      So, after using the sun, wate

    • "How did they figure out how to set the clock initially? Thanks." They killed Christ. You're welcome.
    • They used astronomical observations. Observatories like Greenwich and the USNO have special telescopes that are designed to detect the exact moment that a star crosses the zenith. This gives you an accurate measurement of the Earth's rotation in the celestial frame of reference.
  • Does it blink 12:00??

    Seriously... how do you set the time on one of them?

    • They automagicly set themselves, I believe.
    • Seriously... how do you set the time on one of them?

      It's just like the clock radio in your bedroom, except the up and down arrow buttons only nudge the time by 1 femtosecond per click.

    • i remember they had a couple of atomic clock units (clocks not just oscilators) on the royal instituation chrsitmas lecutres series (broadcast on the bbc) and they had some kind of computer setup that they could use to bring them very very close to synchronised.

      with the expermental uses theese clocks get put too its not about the absoloute set time its about synchronising the clocks then haveing them behave in a very consistant matter from then on (obviously allowing for relativistic effects from moving th
    • In the old days, it was common to use "flying clocks" to synchronize atomic clocks around the world. A flying clock is just a portable version of an atomic clock, with a rechargeable battery for its power supply. Someone would take the flying clock to the place where the primary time standard was maintained, synchronize it with the primary time standard, and hop on a commercial airplane flight to the field site. When they arrived at the field site, they would synchronize the local atomic clock with the flyi
  • sometimes you will read about how the most accurate clock in the world is accurate to within 1 second every 30 million years or so. if it is already the most accurate clock, how would they know this?
    • The best way to evaluate a clock's accuracy is to build several, and then compare them. The amount by which they differ after some interval tells you how good the clocks are. Of course that method relies on the assumption that the errors of different clocks are uncorrelated. The physics of these clocks is very well understood though, so the claim is that no known physical processes will cause correlated errors.

    • Re:question (Score:3, Informative)

      by iabervon ( 1971 )
      The definition of the second is now based on the physical quantity that atomic clocks measure, so the clocks are, when functioning properly, correct by definition. They can therefore just look at how much agreement a bunch of clocks have with each other. That is, they don't have to worry about the issue of all of the clocks being systematically fast or slow, like if they were mechanical watches which could all be consistant, but all tick at a rate different from a second, because the second is defined such

  • Strontium Clock (Score:4, Interesting)

    by rakeem ( 157080 ) on Saturday June 04, 2005 @08:14PM (#12726591)
    Anyone see that article a couple of weeks ago in New Scientist about Strontium atoms held in standing waves generated by 6 lasers? Mental. A 50 time more accurate (or something).

  • I guess this is a good time to mention... (Score:5, Funny)

    by Ann Elk ( 668880 ) on Saturday June 04, 2005 @08:25PM (#12726631)

    ...the worlds first atomic wristwatch [leapsecond.com].

  • So, most of the non-live TV shows are on time. It is probably impossible. :(
  • ... the atomic clock, is celebrating its 50th year.

    Fine but what nanosecond does its birthday roll over?

  • 49.999999999999999999923409
  • I guess I'm just not getting all this timekeeping stuff. I've been aroud for over 1,308,744,000+ seconds and I still don't _feel_ any older...
  • and all the staff had a surpise birthday party for the bi-centinary birthday.

    Although the surpise was too much for dear old atomic, and his ticker stopped ticking. He was rushed to hospital where he had a pacemaker installed. He has lost several hours which officials have decided to relocate him to a warmer climate on a different timezone to make up for the difference.

    The operation and pacemaker will not shorten the expected lifespan of atomic.
  • Now, tell me exactly when it first became operational, down to the precise NANOSECOND!

  • Atomic Clock Turns 50 (Score:4, Funny)

    by citking ( 551907 ) <(ten.gniktic) (ta) (yaj)> on Saturday June 04, 2005 @09:36PM (#12726902) Homepage
    Atomic Clock Turns 50

    Uh huh, that's what it wants us to think....

  • something that doesn't exist.
  • I mean, it could be lying about its age. If you disagree, what clock can you consult for arbitration?
  • According to the article, [nist.gov] it doesn't appear there were any previous celebrations ... and in the BBC piece [bbc.co.uk] it doesn't say if the clock got to do anything for turning 50. I climbed a mountain on my 40th birthday [komar.org] - someone ought to throw a party for the poor old clock! ;-)
  • 50.00000000000000000000014 years (with uncertanity +/-2 in the last decimal place)

Slashdot Top Deals

I've noticed several design suggestions in your code.

Close