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Playing With Atomic Clocks At Home

Posted by kdawson on Tue Dec 11, 2007 08:01 AM
from the as-i-was-walking-down-the-street-one-day dept.
Hardware Hacking Science
Wired is running a profile of the Time Nuts, a small group of people who buy surplus precision time equipment — cesium clocks for example — on eBay and keep really accurate time, because they can. The article quotes Tom Van Baak, who has outfitted a time lab superior to those of many small countries: "If you have one clock... you are peaceful and have no worries. If you have two clocks... you start asking, 'What time is it, really?'"
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Feed: Amateur Time Hackers Play With Atomic Clocks at Home by wiredfeed (969535)
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  • Clearly.... (Score:5, Funny)

    by Smidge204 (605297) on Tuesday December 11 2007, @08:02AM (#21654265)
    ...Some people have too much time on their hands.

    =Smidge=

    • Re:Clearly.... (Score:5, Funny)

      by Kranfer (620510) on Tuesday December 11 2007, @08:18AM (#21654403) Homepage Journal
      This is no time to argue about time, we don't have the time!
    • and "it's ticking away with my sanity...."

    • Please read the article (Score:5, Funny)

      by fishdan (569872) on Tuesday December 11 2007, @08:52AM (#21654731) Homepage Journal

      Your missing out if you only skimmed the article. Make sure you find this gem:

      When the family returned to the suburbs two days later, the cesium clocks were off by the precise amount relativity predicted. He and his family had lived just a little more life than the neighbors.

      An amazing PROOF that time is actually affected by gravity. We still know so little (ahem) relatively about time in physics, that seeing evidence of it being manipulated in this manner is awesome. will there be giant contained gravity wells in ambulances to slow time while patients are rushed to the hospital? Will I be slowing down time so I can get First Post AND spell check? The possibilities are endless!

      • Re: (Score:2, Funny)

        by Anonymous Coward
        >>Will I be slowing down time so I can get First Post AND spell check?

        I'll give you benefit of the doubt that you put that line in AND then deliberately misspelt the first word in your post. So assuming that -- bravo! You rarely see that sort of self-aware irony.

        You're totally right though about the relativity stuff. Amazing

      • Re:Please read the article (Score:4, Informative)

        by brunes69 (86786) <slashdotNO@SPAMkeirstead.org> on Tuesday December 11 2007, @09:20AM (#21655023) Homepage
        You do know that they proved this like 60 years ago right, when the first Atomic clocks were produced.... In addition there is an atomic clock on the shuttle. The time difference between it and it's perfectly synchronized counterpart on earth is very visible.

        • Re:Please read the article (Score:4, Insightful)

          by sg3000 (87992) * <{sg_public} {at} {mac.com}> on Tuesday December 11 2007, @10:45AM (#21656099)
          > You do know that they proved this like 60 years ago right

          Yeah, but what made it cool was that the experiment could be repeated by a regular guy with surplus stuff from Ebay.

          "If you have one clock ... you are peaceful and have no worries," says Van Baak... "If you have two clocks ... you start asking, 'What time is it, really?'"

          Well, maybe not a regular guy, but you get the idea.

      • The real reason (Score:5, Funny)

        by jgoemat (565882) on Tuesday December 11 2007, @09:50AM (#21655345)
        Isn't it obvious? It wasn't relativity, the family lived an extra 22 milliseconds because they drove up a mountain and were closer to God. That's the only logical solution, I can't see this "gravity" you speak of. Every time someone has a problem with time physicists think they can solve it just by throwing a few nanoseconds at it. Ridiculous...

        • Re:The real reason (Score:5, Informative)

          by timeOday (582209) on Tuesday December 11 2007, @10:31AM (#21655897)

          Isn't it obvious? It wasn't relativity, the family lived an extra 22 milliseconds because they drove up a mountain
          After noticing your comment I read the whole article just because 22 ms sounded like an impossibly large relativistic effect for a car. It was actually 22 nanoseconds. You're off by a factor of a million.

      • Re:Please read the article (Score:4, Funny)

        by ari_j (90255) on Tuesday December 11 2007, @10:24AM (#21655779)
        Yes, anyone with a cesium clock at home lives just a little more life than his neighbors.

    • Re: (Score:3, Insightful)

      by sm62704 (957197)
      Funny yet insightful! How to mod, how to mod.

      Some people are way too anal. Jees, my ten dollar alarm clock is accurate enough for me, as are the cheap wall clocks, none of which ever differ by more than a minute.

      I have to set my clocks twice a year anyway. I don't have time to worry about what time it is.

      Next on slashdot: Obsessive Compulsive Disorder: Hallmark of the nerd? [wikipedia.org]

      -mcgrew [slashdot.org]

      -
    • Years ago, my wife got me an indoor/outdoor thermometer that also included a radio-synced clock that works with WWV. Between that and NTP on my computers, time is kept close enough.

      Besides, the only time that *really* matters down to the minute is when you're trying to record a TV show, and *they* aren't that accurate.

      So it just doesn't matter.

      Makes me think of the line by the disillusioned engineer in Tracy Kidder's "Soul of a New Machine," "I'm going to a commune in Vermont where I don't have to deal wi

      • Re: (Score:2, Interesting)

        by Anonymous Coward
        > Besides, the only time that *really* matters down to the minute
        > is when you're trying to record a TV show

        Just because you have limited imagination..

        For example, when correlating long-baseline interferometer data
        from amateur radio astronomers there is ABSOLUTELY a requirement
        to have sub-millisecond accuracy.

        And that's just one example from recent experience.

  • hm. (Score:3, Funny)

    by toQDuj (806112) on Tuesday December 11 2007, @08:03AM (#21654271) Homepage Journal
    I like to be REALLY just on time for my meetings...

  • As Linus might say (Score:5, Funny)

    by CRCulver (715279) <crculver@christopherculver.com> on Tuesday December 11 2007, @08:03AM (#21654273) Homepage
    Real men just run ntpd and let the whole world keep time for them.

  • Stop. (Score:5, Funny)

    by RandoX (828285) on Tuesday December 11 2007, @08:10AM (#21654323)
    Hammer time.

  • Am I the only one... (Score:3, Funny)

    by Anonymous Coward on Tuesday December 11 2007, @08:13AM (#21654355)
    ...who can have two or more clocks and not constantly ask myself "what time is it?... really?"
  • Keeping accurate clocks synchronized is great and all..that is until accidental light-speed travel makes the whole thing pointless.
  • an article came up about atomic clocks and perfect time and I said...

    Does anybody really know what time it is?
    Does anybody really care?
    If so I can't imagine why
    We've all got enough time to troll....

    My apologies to Chicago.

  • Q-physics (Score:4, Funny)

    by mach1980 (1114097) on Tuesday December 11 2007, @08:23AM (#21654451)
    If you really, really know what time it is. You will find yourself quite lost. Darn that Heisenberg!
    • Actually, you'll find yourself with quite indeterminate energy. Somewhere between college senior and Richard Simmons. Those are the two recognized physical limits on human energy states.
  • ... to my watch I do have time to respond.

    However, according to my computer I don't.

    Interestingly, my boss concurs with my computer.

  • See Time Fly (Score:3, Funny)

    by Dareth (47614) on Tuesday December 11 2007, @08:36AM (#21654569)
    I always said it was fun to throw a clock out a high window so you could see time fly!

    One must much more careful with these new atomic clocks. After time flies, they explode and destroy whole cities!

  • First post (Score:5, Funny)

    by carpe_noctem (457178) on Tuesday December 11 2007, @08:40AM (#21654607) Homepage Journal
    This is really the first post; your clocks just don't agree with mine.
  • Radio controlled clocks are sometimes called atomic clocks because their underlying time resides in a Colorado atomic clock.
    These clocks give accuracy within a second as does the ntpd daemon on Unix computers.
    The world seems in balance when you set 3 radio controlled clocks in front of your computer,
    then watch all four with the same hour, the same minute, count the same seconds.
    You shouldn't tell your clock the time -- your clock should tell you the time,
    which radio controlled clocks and computers running n

    • On the subject of german radio clocks: A well-meaning, elderly german friend or relative of my mother once sent her a radio clock as a christmas present. Since you have to be within about 2000km of Frankfurt/Main to receive the signal, and since it would not run without at least a first boot-up signal, this was not a very practical present, seeing that my mom lives in South Africa. I think she sent it back to someone else the following xmas.

      I wouldn't mind a clock though that picks up its signal from the G

  • What's the fascination with uber-accuracy at home? Hell, I'm perfectly content with "about" accurate stuff. Kinda reminds me of weather forecasts. I remember when the weather forecast was "High in the upper 60's". If it was 46 or 70, no one complained. Now, it's "High today is 72" and people bitch when it reaches a sweltering 73.

    For many services and uses, highly-accurate clocks have their place, but for every-day home use?

    • If it was 46 or 70, no one complained.

      Oops, that should have been "66", not "46".

    • Re: (Score:3, Insightful)

      by Alioth (221270)
      It's a hobby. Some people like to ride, say, horses for a hobby. Not terribly useful now everyone has cars. What's the use? The use is that someone enjoys doing it. Like the horse rider, the time keeping hobbyist enjoys tinkering with highly accurate time pieces.

      If you have to question why people have hobbies you don't find interesting, you're amazingly lacking in imagination.
      • Maybe he meant practical uses? Like, say, crypto? Say there's a universally accessible source of noise (such as background microwave radiation) which both Bob and Alice sample and digitize at a given rate starting from an "offset" in time known only to the both of them. They now have an arbitrarily long one-time pad at their disposal!

    • Re:I don't get it. (Score:4, Informative)

      by ChrisA90278 (905188) on Tuesday December 11 2007, @01:24PM (#21659271)
      What's the fascination with uber-accuracy at home?

      They are calling these "clocks" only because that is what the typical reader understands. A better term is "frequency standard". There are many uses for a stable frequency, the most common one is running a microwave transmitter. This is the major source of the surplus devices too, from cell towers. As the phone companies modernize equipment these "clocks" find their way to eBay and then into people's houses.

  • The true obssessive (Score:3, Funny)

    by elrous0 (869638) * on Tuesday December 11 2007, @09:10AM (#21654905)
    I would bet money that at least one of these guys adjusts for the speed of light between his eyes and the average viewing distance to his clock.

    I would also venture to guess that he has no girlfriend.

    • Well, at least the one mentioned in the article reproduced already.

      Maybe this is what geeks should do. Pretend to be normal people for a few months, get married, have children, and THEN fill the house with strange hardware.

  • Half way solution: GPS (Score:5, Informative)

    by FridayBob (619244) on Tuesday December 11 2007, @09:37AM (#21655205)
    NTPD isn't good enough for me -- bad weather on the Internet has caused my server to loose synchronization one too many times, which can be mighty irritating when comparing your log files with those of other systems. On the other hand, acquiring an atomic clock seems a bit over the top to me. So, I figured a good compromise solution would be to connect a GPS receiver to my serial port and synchronize NTPD to that. I've ordered a Garmin GPS 18 OEM LVC [garmin.com] that I will receive later this month (hopefully). According to these instructions [qnan.org] it's not that difficult to set up, while the result is microsecond precision on Linux 2.6 and nanosecond precision on BSD -- good enough for me. All you need to do is to make sure that your GPS device has a reasonable view of the sky.
      • not to mention NMEA 0183 is specced to 4800 baud rs232!

      • Re: (Score:3, Informative)

        by russotto (537200)
        With a GPS time source you get the time value (in ASCII) through a serial port, but the synchronization is done through a pulse per second interrupt. So the latency on the serial bus doesn't matter as long as it is significantly less than one second.
  • Sure, he's got all those fancy clocks in his "Time Lab", but they only go forward!

    - RG>
  • Does anybody really care? If so I can't imagine why, We've all got time enough to cry . . . . (For all the oldsters out there)
  • They got the saying all wrong. It goes "A man who wears one watch always knows what time it is; a man who wears two watches is never sure."

  • "If you have one clock... you are peaceful and have no worries. If you have two clocks... you start asking, 'What time is it, really?'"
    If you have an entire garage of clocks, you can scare the shit out of your teenage neighbor when they all strike 8:00 AM.

    For extra fun, tell him that they are all twenty minutes slow, making him late for school.
    • If you fill your garage with clocks, where will you park the DeLorean? /Get back, Marty //guitar riff goes here

  • How to set? (Score:3, Interesting)

    by russotto (537200) on Tuesday December 11 2007, @11:12AM (#21656641) Journal
    OK, as much fun as it would be to have my own stratum-1 NTP server, how do you (read: some ordinary joe, not a university researcher) synchronize these things to TAI in the first place?

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