Slashdot Mirror

← Back to Stories (view on slashdot.org)

Keeping Time with a Mercury Atom

Posted by ryuzaki0 on from the nice-watch dept.

Roland Piquepaille writes "The National Institute of Standards and Technology (NIST) has announced that a new experimental atomic clock based on a single mercury atom is now at least five times more precise than NIST-F1, the U.S. standard clock. This mercury atomic clock 'would neither gain nor lose a second in about 400 million years' while it would take 'only' 70 million years to NIST-F1, based on a 'fountain' of cesium atoms, to gain or lose a second. But even if this new kind of optical atomic clock is more accurate than cesium microwave clocks, it will take a while before such a design can be accepted as an international standard. A ZDNet summary contains pictures and more details about the world's most precise clock."

7 of 153 comments (clear)

  1. How much accuracy do you need? by tylernt · · Score: 2, Interesting

    So... at what point do you say that a clock is accurate enough? I mean, yeah maybe this thing is more accurate than current technology, but if it turns out to be way more expensive, why bother? How often do you need the accuracy that current technology can't provide?

    --
    DRM 'manages access' in the same way that a prison 'manages freedom'
    1. Re:How much accuracy do you need? by Detritus · · Score: 2, Interesting

      We can always use more accuracy. Many communications systems rely on accurate clocks to keep the transmitters and receivers in synchronization. Frequency stability is also important for communications systems and test and measurement equipment. Any defects in the clock will degrade the performance of the equipment.

      --
      Mea navis aericumbens anguillis abundat
  2. Why? by mh101 · · Score: 2, Interesting

    Can someone explain why we even need this sort of precision?

    --
    Duct tape is like the Force. It has a light side, a dark side, and it holds the universe together.
  3. I Know I'm Missing Something Here... by stuffman64 · · Score: 3, Interesting

    I'm just curious about something here. If a second is defined to be 9,192,631,770 oscillations of a Caesium-133 atom, then why is it said atomic clocks are accurate to within a second over 70 million years? Isn't that lost/gained second itself defined by the Caesium atom's transitions? I hope this question makes sense...

    --
    --- At my sig, unleash hell.
  4. Re:Universal clock? by pontifier · · Score: 2, Interesting

    http://en.wikipedia.org/wiki/Clock_of_the_Long_Now

    --
    -John Fenley
  5. Re:How accurate is accurate enough? by rwwh · · Score: 4, Interesting
    Scientific American once had a nice paper about time. I remember these two facts:
    • At an accuracy of 10^-17, the earths gravity makes that two identical clocks, one of which is 5cm higher up than the other one, will start deviating from each other (i.e. time really IS different 5 cm up, at this accuracy)
    • At an accuracy for 10^-17, relativistic effects start playing a role at walking speeds (i.e. time really IS different at walking speed than at rest, at this accuracy).
    I think 5cm and 5km/hour are reasonable usability limits, hence an accuracy of better than 1:10^17 would not make much sense to me.
  6. Re:One small problem... by oskay · · Score: 3, Interesting

    The clock is based on mercury-199. Yes, it's a stable isotope.