Tuesday, December 09, 2008

Three...Two...One...One...Happy New Year!

December 31st will officially be one second longer than a normal day. A whole second! When will it end? The keepers of the national atomic clock just announced that they will be adding on an additional leap second to the last day of the year. Maybe it's just an excuse to keep their New Year's parties going as long as possible.

The atomic clock at the Naval Observatory in Washington DC is the official time keeper of the country. It works by measuring the frequency of microwave radiation emitted by the element cesium-133. This is the gold standard for clock accuracy (the cesium standard really) the whole country bases its measure of time off of it. The trouble is it's more accurate than the planet's rotation itself!

The revolving Earth is a pretty good time keeper, but because of the laws of motion, it isn't perfect. The planet is little by little slowing down, so every now and again the time keepers have to add a second to the atomic clock to keep everything synced. Starting in 1972 they've included a leap second every few years or so, most recently in 2005.

One second of variation may not seem like a lot, but to sensitive measurements for GPS systems and the like, it can make a world of difference.

Even though the official clock needs tweaking from time to time, it's hands down the most accurate way to see how much longer until The Tonight Show. Hundreds of systems sync up with the official time (likely your cell phone for one) and it may be possible one day to buy your very own atomic timepiece. Experts have been working on miniaturizing the massive atomic clock in the Naval Observatory to a system that could fit on your wrist. Of course, it may be years before Rolex has its own Cesium line, but the implications are tremendous. Atomic-age accuracy for cooking a three-minute egg is just the beginning.


  1. Oh, dear. You mention cesium atomic clocks but your picture is of a mercury ion frequency standard, and you mention the US Naval Observatory but link to the wikipedia entry for NIST's atomic fountain.

    Miniature clocks are being worked on, but not of the sort in the link … yet. "Magic wavelength" clocks are a long way off.

  2. Good catch! I updated the link to the offical USNO website. The picture, I'll keep though, it looks too nice to take down.

  3. I love reading your blogs!

  4. I Love it... its nice..

  5. Great blog... thought you might like this
    Happy New Year in 15 Languages