Want to read Slashdot from your mobile device? Point it at m.slashdot.org and keep reading!

 


Forgot your password?
Close
typodupeerror
×
Science Technology

New Most Precise Clock Based On Aluminum Ion 193

Posted by ScuttleMonkey from the many-stitches-in-time dept.
eldavojohn writes "The National Institute for Standards and Technology has unveiled a new clock that will 'neither gain nor lose one second in about 3.7 billion years,' making it an atomic clock twice as precise as the previous pacesetter, which was based on mercury atoms. Experts call it a 'milestone for atomic clocks.' The press release describes the workings: 'The logic clock is based on a single aluminum ion (electrically charged atom) trapped by electric fields and vibrating at ultraviolet light frequencies, which are 100,000 times higher than microwave frequencies used in NIST-F1 and other similar time standards around the world.' This makes the aluminum ion clock a contender to replace the standard cesium fountain clock (within 1 second in about 100 million years) as NIST's standard. For those of you asking 'So what?' the article describes the important applications such a device holds: 'The extreme precision offered by optical clocks is already providing record measurements of possible changes in the fundamental "constants" of nature, a line of inquiry that has important implications for cosmology and tests of the laws of physics, such as Einstein's theories of special and general relativity. Next-generation clocks might lead to new types of gravity sensors for exploring underground natural resources and fundamental studies of the Earth. Other possible applications may include ultra-precise autonomous navigation, such as landing planes by GPS.'"
This discussion has been archived. No new comments can be posted.

New Most Precise Clock Based On Aluminum Ion More

New Most Precise Clock Based On Aluminum Ion

Comments Filter:

  • that I've got very little hope of the clock at work running fast, anymore, eh?

    • eh?

      You Canadians keep your hands off our clock.

    • Even Better (Score:5, Insightful)

      by causality ( 777677 ) on Friday February 05, 2010 @01:04PM (#31036918)

      For those of you asking 'So what?' [ ... ]

      Do you have any idea how many Slashdot articles could benefit from such an explanation?

    • Re: (Score:2, Interesting)

      by alexj33 ( 968322 )

      will 'neither gain nor lose one second in about 3.7 billion years,'

      What clock are they going to check it against to verify its accuracy?

      And if there is such a clock, why isn't that clock being tested instead?

      • >> What clock are they going to check it against to verify its accuracy? Stonehenge

      • What clock are they going to check it against to verify its accuracy?

        Another aliminum clock, I'd imagine. Fire up a bunch of them and see how much their readings deviate after some time (measured as the median of their readings).

  • I unplugged the atomic clock by mistake. I was just brooming around and I knocked out this here plug. Anyone know what time it is?

    • Re:Ah, I unplugged the atomic clock... (Score:5, Funny)

      by sconeu ( 64226 ) on Friday February 05, 2010 @12:37PM (#31036544) Homepage Journal

      Does anybody really know what time it is?
      Does anybody really care?

    • Been there, done that. The critical element of the device fell out. The only question is, "How long until the planet disappears"? [wikipedia.org]

    • Re:Ah, I unplugged the atomic clock... (Score:5, Interesting)

      by deglr6328 ( 150198 ) on Friday February 05, 2010 @02:04PM (#31037678)

      The long list of lame jokes that would inevitably accompany this article are obvious and unsurprising. But these "oooh now I can get to my next meeting within one yoctosecond of it starting" jokes may be more apt than you realize. There is a real issue of how to even use a clock this accurate at all. This new Al ion clock is supposedly accurate to one part in 10^17, yes? An article I read in SciAm ~8 years ago predicted this milestone would be reached within the decade, and it seems they were right. The problem is, you will introduce a relativistic time dilation to a clock with an accuracy on the order of 1 in 10^17 merely by walking down the street with it. Similarly, you will experience a comparable magnitude of time dilation by reducing the earth's gravity you experience by raising your elevation off the ground by only 10 centimeters. Aside from pure physics experiments like measuring a potential variation in the fine structure constant since the beginning of the universe and such, I don't know how practical application of a clock this accurate could be achieved. For instance, even if you manage to get a time standard of this level accuracy aboard a GPS satellite, you need to know the satellite's location in orbit, it's "ephemeris data", to an equal degree of accuracy in order to make use of such a time standard. Is that even possible? How do you transfer a time standard of such extreme precision between two clocks while preserving its integrity? If that can't be done, what is the practical use of an absolutely stationary clock that can never be moved? Even for the measurement of the fine structure constant at something like 1/10^18, you will have to take into consideration the movement of the continent due to plate tectonics and the movement of magma bubbles in the planet's mantle in order to have confidence in the accuracy of your answer.

      • The positioning thing should be solvable by the satellites pointing lasers at each other. Or something comparable.

        The rest is math, and then earth’s and your relative position to that grid is the only inexact factor.

      • Re:Ah, I unplugged the atomic clock... (Score:5, Interesting)

        by jmizrahi ( 1409493 ) on Friday February 05, 2010 @03:02PM (#31038530)
        You are absolutely correct, the time measured by such a clock is going to be dependent on general relativistic effects, most prominently by distance from the mean geoid. However, I fail to understand how you jump from that to concluding that it's useless. For example, you could use such a clock to make precision measurements of general relativity and test possible extensions. Moreover, a clock that sensitive should be able to "feel" changes in gravity caused by density fluctuations in the Earth. This could help find oil deposits, for example. The summary says as much. Generally speaking, you NEVER lose by increased precision. It is true that if your specific application is limited by low precision in some other component, you won't gain by increasing precision somewhere else. However, that's not the case here. I'll admit that I don't know enough about GPS and satellites to answer your specific question, but my impression is that they currently ARE limited by time standards.

      • Re:Ah, I unplugged the atomic clock... (Score:5, Interesting)

        by IICV ( 652597 ) on Friday February 05, 2010 @03:29PM (#31038882)

        Allright then - you take twelve of these clocks, grouped into clusters of three, arranged in the shape of 3D right angle with each cluster as far away from the other as possible. You isolate them as well as you can, so that they are not disturbed by local vibration and other such things. Probably the best thing to do would be to launch them into space.

        Then you measure their time differences.

        If there's any differences, assuming you've isolated them well enough and are filtering out the expected noise, those differences must be due to external gravity waves.

        Tadaa, we've got a gravity wave antenna. Maybe someone's talking in that spectrum.

      • Re: (Score:2)

        by tsotha ( 720379 )
        That's what I was wondering. With those kinds of relativistic influences emerging as considerations, it seems like they're past the point where additional accuracy provides any sort of real benefit.
        • Space and time are one. The more accurately we can measure time, the more accurately we can measure space.

      • Re: (Score:2)

        by Bengie ( 1121981 )

        that's the idea. time dilation is very useful in lots of math. Like the other guy said, link two satellites together via a laser and measure the difference in dilation as they pass over different parts of the earth. lots of other useful things to.

      • Aside from pure physics experiments like measuring a potential variation in the fine structure constant since the beginning of the universe and such, I don't know how practical application of a clock this accurate could be achieved.

        I was thinking maybe for a near-term application you could look for prospecting or seismographic uses of this. You know, place a widely-spaced array of clocks on a large section of land and use the extreme precision to measure gravitational anomalies. May tell you something about density changes of material in the Earth. I dunno; the most obvious application is probably to shoot a few of these into space and look for gravity waves, but if by 'practical application' you mean actually practical, prospecti

    • Re: (Score:2)

      by ozbird ( 127571 )
      NTP FTW!

  • Extraordinary claims (Score:4, Funny)

    by Locke2005 ( 849178 ) on Friday February 05, 2010 @12:30PM (#31036442)
    The National Institute for Standards and Technology has unveiled a new clock that will 'neither gain nor lose one second in about 3.7 billion years' Sure, they say that now, but just TRY tracking them down to get your money back 3.7 billion years from now when you find out they were lying!

    • Re: (Score:3, Insightful)

      by pnewhook ( 788591 )

      Or if they move it. Once they do general relativity takes over and the time is now 'wrong' according to a stationary observer.

    • but just TRY tracking them down to get your money back 3.7 billion years from now when you find out they were lying!

      If they were lying, then presumably you'd be aware of it before the 3.7 billion years had passed.

    • But what are you going to compare it to in order to find out?

  • Marketing angle (Score:5, Funny)

    by sakdoctor ( 1087155 ) on Friday February 05, 2010 @12:37PM (#31036548) Homepage

    For the domestic market they can use the marketing angle that aluminium is safer than mercury, and that it will case less pollution when you come to trade it in.

    In fact, I think I'll order one now.

    • Re:Marketing angle (Score:4, Funny)

      by RealErmine ( 621439 ) <commerceNO@SPAMwordhole.net> on Friday February 05, 2010 @12:45PM (#31036650)

      For the domestic market they can use the marketing angle that aluminium is safer than mercury, and that it will case less pollution when you come to trade it in.

      In fact, I think I'll order one now.

      Everyone knows that aluminum is an intermediate material in terms of durability and weight reduction. Wake me up when it is replaced with carbon fiber.

      • But carbon fiber breaks without showing any deformations before it happens.
        So when such a clock would be off, it would be off by millions of years. ;)

  • It's about time (Score:3, Funny)

    by Switchback ( 6988 ) on Friday February 05, 2010 @12:39PM (#31036574)
    Well this is money well spent. I mean, having to correct my clock every 100 million years was becoming just too laborious.

  • Plane landings? (Score:5, Insightful)

    by Dynedain ( 141758 ) <slashdot2&anthonymclin,com> on Friday February 05, 2010 @12:39PM (#31036576) Homepage
    If you need a clock that's accurate to 8.6 x 10^-19 seconds in order to land a plane, you're probably doing it wrong.

    • Re:Plane landings? (Score:5, Informative)

      by ircmaxell ( 1117387 ) on Friday February 05, 2010 @12:50PM (#31036738) Homepage
      You need that kind of precision to do it from several hundred miles away (As is what happens with GPS). The Satellites all have clocks on board that are synchronized and constantly transmit the time. A GPS receiver simply needs to listen to a few of the satellites, and compute the difference between their times to determine the location. The kicker of it is that since the satellites are moving at fast speeds (relative to us), the time of their clocks are different from "our" time. So special relativity is used to counter those relativistic effects. So basically, GPS is only as accurate as the clocks that form its backbone. That's one of the reasons why unaugmented GPS is limited in accuracy to a few meters. Improving the accuracy of the clocks (by orders of magnitude) has the potential to cut down a few meters to potentially tens of centimeters... You'd need that level of accuracy to land a plane... Planes "flare" during landing (slowing the rate of decent to nearly 0 just as the wheels touch down). Plus or minus even one meter in any direction (up, down, forward, back, side to side) could be catastrophic. So current "autoland" autopilots use radar altitude and ground based ILS (radio based navigation) to gain the necessary precision. If GPS accuracy gets good enough to where you don't need those aux systems (or need them as primary at least), complexity of autopilots would drop significantly...
      • Mod up. The relationship between space and time is very interesting and parent has a good explanation. GP is doing it wrong.

        • Re:Plane landings? (Score:4, Informative)

          by plover ( 150551 ) * on Friday February 05, 2010 @01:30PM (#31037266) Homepage Journal

          But his assumption that clock error is responsible for all of the current lack of precision is wrong. Clock error is responsible for probably less than a third of the current error. Atmospherics, multipath reflections, and ephemeris errors account for the bulk of the error.

          Sure, every improvement is an improvement. But these clocks are not a magic bullet that will magically grant centimeter precision.

          • That's why I said:

            So basically, GPS is only as accurate as the clocks that form its backbone. That's one of the reasons why unaugmented GPS is limited in accuracy to a few meters. Improving the accuracy of the clocks (by orders of magnitude) has the potential to cut down a few meters to potentially tens of centimeters...

            I did acknowledge that it's not the only part of the accuracy equation. However, since it (as you say) accounts for somewhere "less than" 33% of the error, it's indeed blocking the progres

          • Correct. Until aluminum ion clocks can compensate for issues in the ionosphere, radar altimeters, WAAS/LAAS, and ILS are still going to be in style.

      • Re: (Score:2, Redundant)

        by Lumpy ( 12016 )

        Um no. You can do guidance without a GPS reference that is pretty darn accurate. In fact, using the various marker transmitters around an airport you can easily detect if you are lined up and on the glide path.

        I remember my IFR training, there is a whole lot of other info for landing an airplane that you have outside a GPS.

        • Re:Plane landings? (Score:5, Informative)

          by ircmaxell ( 1117387 ) on Friday February 05, 2010 @01:14PM (#31037018) Homepage
          Correct, which is why I said in my post that ILS and radar altitude are needed at the present time. Radar altitude systems are prohibitively expensive and big (pretty much only usable on commercial airliners and in military applications). ILS is good for approach, but you can't land off it. It'll get you down to 50 feet AGL (or less in certain areas), but it won't get you though the flare. That's because the glideslope portion of the ILS signal is set a 3 degrees. So it can only tell you your relation to the 3* slope, not distance above the ground (which is what's really needed when you're over the threashold). ILS gets you aligned with the runway, and onto the proper approach path. It's an approach system, not a landing system (and was never designed as such)... For an ILS system without a radar altimiter, the pilot always must handle the actual landing. (hence the classes of autopilot, and existence of a decision height -- The height which you need to either be able to proceed visually, or abort the approach)... That's why autoland based on GPS is such an interesting thing. It would enable cheaper autoland systems which are a lot smaller than present systems (Basically business jets and light aircraft could potentially be equipped) and don't depend on airport infrastructure. So you could theoretically autoland on a small General Aviation airport...

          I do have my Private Pilots license with Instrument rating, but I also love physics...

          • I would think the primary issue with using civilian GPS for an application like this is that it is a degradable, government-controlled signal. A warning of a terrorist attack could suddenly lead to the signal turning to degraded mode, and then a plane in process of landing might think it's several meters away from where it actually is. That could lead to something bad happening I imagine.

            • The US can selectively degrade GPS by geographic region. If they degrade it intentionally over US soil because of an attack, I'm far more concerned over other issues than GPS being degraded.
          • ...and continuing this line of thought, the "flying cars" we hear about from time to time could use such an auto-land feature. Making the technology cheaper is part of what has to happen for that technology to "take off".

      • Re: (Score:3, Informative)

        by Burdell ( 228580 )

        The relativistic speed means their clocks run slower than clocks sitting still on Earth, according to special relativity. Another source of GPS time difference is that they are farther away from the center of Earth's gravity than we are, so according to general relativity, their clocks run faster than clocks on Earth. Both factors have to be taken into account.

      • Funny, this car [slashdot.org] is already accurate to 2cm using GPS.

        1m in plane landings may be catastrophic, but 2cm certainly is not. And GPS can pinpoint your location, but gives you no information on up-to-date ground conditions. For this, local sensing ability (like radar) will always be necessary.

        • 1m in plane landings may be catastrophic,

          Actually that's not likely. If the runway tolerances are so tight, you wouldn't be trying to land there, let alone autoland there. You're talking about a runway which has +- 1m for the airplane to safely remain within. Someone would be looking for a different runway. Generally speaking, on small planes land on such runways.

      • Yeah but you get lots of error in transmission losses, and reflections. The clocks are accurate enough, the actual positions of the satelites, and the reflections, and absortions of the signals are what gives you error.

      • Re:Plane landings? (Score:5, Informative)

        by mpe ( 36238 ) on Friday February 05, 2010 @02:09PM (#31037724)
        Improving the accuracy of the clocks (by orders of magnitude) has the potential to cut down a few meters to potentially tens of centimeters... You'd need that level of accuracy to land a plane... Planes "flare" during landing (slowing the rate of decent to nearly 0 just as the wheels touch down). Plus or minus even one meter in any direction (up, down, forward, back, side to side) could be catastrophic. So current "autoland" autopilots use radar altitude and ground based ILS (radio based navigation) to gain the necessary precision.

        "Full blind autoland" systems have been around since the 1960's An unexpected problem with the first systems is that they were "too accurate", runways wear out quickly if touchdown always happens in the same place.

        If GPS accuracy gets good enough to where you don't need those aux systems (or need them as primary at least), complexity of autopilots would drop significantly...

        Most landings are performed by pilots. Even in an autoland situation the pilots go through similar procedures to if they were flying the plane. Otherwise things are likely to end up like TK1951.
      • The difference between current atomic clocks and a perfect atomic clock would only result in a fraction of a millimeter in positioning difference, tops.
    • I, for one, want my planes landed to a quarter of a nanometer [google.com.ar]
  • Forget the 3.7 billion year thing. What's important is this thing's accurate to one part in 10^17. Correct me if I'm wrong, but it'll probably run faster or slower depending on how close you stand to the thing.

    On toppa that, it never needs winding.
    • I was thinking the same. Housing the device so it would be unnafected by gravitational anomalies would be quite challenging...
    • I don't get this. How will it run faster or slower? doesn't it run at a constant rate.?

  • Other possible applications may include ultra-precise autonomous navigation, such as landing planes by GPS.'

    IIRC, not only do we already have this capability, but they had to design in some wiggle room because the precision touchdowns were hammering runways on the same spot until they started to break.

  • The extreme precision offered by optical clocks is already providing record measurements of possible changes in the fundamental "constants" of nature ...

    Hang on. Those bits of matter we're using to determine potential changes to physical constants are governed by physical constants. If every 1-meter rod in the world suddenly became a 1.0001-meter rod while we weren't looking, how would we know?

    • Re: (Score:2)

      by blueg3 ( 192743 )

      It shouldn't shock you to learn that the fundamental constants that influence the behavior that drives the clock are different from the fundamental constants whose change they're interested in measuring.

  • If you just wanted an atomic wristwatch here is the first real atomic wristwatch. Not those fakes which use radio reception

    http://www.leapsecond.com/pages/atomic-bill/ [leapsecond.com]

  • 3.7 billion years from now ... (Score:5, Funny)

    by Korbeau ( 913903 ) on Friday February 05, 2010 @12:46PM (#31036670)

    neither gain nor lose one second in about 3.7 billion years

    Location: 3.7 billion years from now, early December, Planet Earth

    Doomsayer: "The ancient "Scientific Community" civilization was so certain a great cataclysm would come in the following months based on their long-lost primitive yet poweful and mythical calculations that they even deemed unnecessary to keep track of time correctly starting this age! The end is near my friends! A new age will come!"

    • The end is near my friends! A new age will come!"

      Well, when the atomic _alarm_ clock goes off, hitting the snooze button will not be an option.

  • I predict another flood of reference standards to hit e-Bay soon. I've been waiting to find a good (affordable) cesium / rubidium standard for a while now. :P

  • accuracy to 1 second in 100 million years is not adequate for landing a plane via GPS?

    • GPS works by triangulating the phase delays of radio signals transmitted from GPS satellites. The accuracy of your position is proportional to the square root of the phase delay of a signal whose frequency is in the Megahertz, so you're losing a factor of 1 to 100 million right there. Add on top of that the scaling factors due to the orbital velocity of the satellites, the rotational velocity of the earth's surface, and the velocity of the airplane, and (for things like landing planes) a seven- to nine-ni

    • Re: (Score:2)

      by mcgrew ( 92797 ) *

      Someone did explain how. Read the comments!

  • Saying you're keeping precise time with an aluminum clock just doesn't sound as cool as saying you're using a cesium fountain clock. The proper Mad Science(tm) approach should involve things like ytterbium lasers and liquid helium, not just aluminum.

    • This is just a first step. In the next phase they hope to reclaim their Mad Science(tm) credentials by switching to transparent aluminum. Cesium is so 1960s.

      Hard to compete with ytterbium lasers, though. Maybe sharks with frickin' yterbium lasers mounted on their heads?

  • I can sleep better knowing that my atomic clock will only lose 1 second in 3.7 billion years instead of 2. My life has been forever changed.

  • Other possible applications may include ultra-precise autonomous navigation, such as landing planes by GPS.'

    As soon as they fix the unintended acceleration and unresponsive braking in earth bound vehicles, they will take the next step, is landing the plane by GPS.

  • I have a serious problem with trying to even imagine how you validate the world's best clock.

    Would you not have to have a better clock to compare it with?

    And how do you know THAT clock is keeping good time?

    And who guarantees that the aluminum ion will always vibrate to that precision?

    Sounds a bit like the old 3-card monte game.

  • One al-U-men-ee-um, two al-U-men-ee-um, three al-U-men-ee-um...
    Yep, pretty accurate, I'd say!

  • "My god... transparent... ALUMINUM?"
    "No no, this is *timekeeping* aluminum. You see, it consists of an incredibly preci-"
    "Traaaaaansparent aluminum... amazing."

Slashdot Top Deals

Every nonzero finite dimensional inner product space has an orthonormal basis. It makes sense, when you don't think about it.

Close