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Nist: New Optical Clock More Accurate Than Cesium

Posted by chrisd on from the lonely-exhibitionsist-ion dept.

LordPhatal writes "NIST researchers have demonstrated a new kind of atomic clock that has the potential to be up to 1,000 times more accurate than today's best clock. The new clock is based on an energy transition in a single trapped mercury ion.

3 of 44 comments (clear)

  1. um by mar1no · · Score: 1, Interesting

    what exactly are they basing time on? what exactly is a second? and how is it that we determine its length?

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    "you sonofabitch i didn't know!"
    1. Re:um by JohnPM · · Score: 2, Interesting

      We know how long a second is. Time as we measure it is based on Earth's rotation and revolution.

      Nah we stopped doing that a long time ago. The revolution of the Earth is slowing down as the Earth sheds angular momentum to the moon. There are other relatively minor effects on the rate of the Earth's rotation. One of the ways we measure change in astronomical periods is by using incredibly accurate atomic clocks.

      The original poster had a very good question: How do we define the second with such accuracy. The answer is basically: arbitrarily. In the end it doesn't matter as long as we all agree on a very accurate estimate.

      As an interesting side note, even the calender is not completely determined yet. Since the number of days in a year is not a round number we have a number of rules for ammending the calender. Everyone knows about the leap year every 4 years. But this rule is skipped on years divisible by 100. The second rule is skipped on years divisible by 400. Even these adjustments are not sufficient and the interesting bit is that IIRC, noone has decided on how to handle additional corrections. The current drift rate is around 1 day in 3300 years, so if you want to book that venue for your 5000 birthday now, it will be difficult to get the date right.

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  2. Hmm.... by rtaylor · · Score: 5, Interesting

    I've always wondered just how they determine how reliable a clock is.

    Afterall, can't measure meters without a meterstick. Do they simply take a N Cesium clocks and average out their time to determine how close a single Mercury based clock sticks to it? Or did I miss the memo where we could acurrately time trillionths of a second?

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    Rod Taylor