eurekalert.org — An experimental atomic clock based on a single mercury atom is now at least five times more precise than the national standard clock based on a "fountain" of cesium atoms, according to a paper by physicists at the Commerce Department's National Institute of Standards and Technology (NIST) in the July 14 issue of Physical Review Letters.
Jul 14, 2006 View in Crawl 4
rasterbatorJul 14, 2006
It's all gonna end in 2012, so why bother?
oskayJul 14, 2006
I was one of the people that worked on the mercury clock. When we say that the clock is more accurate, what we are really talking about is frequency reproducibility. That is to say, we know that the spacing between any two "clock ticks" coming out of the mercury clock is more constant than the spacing of ticks coming out of the cesium clock. The accuracy of these clocks is evaluated by measuring the effects of different possible perturbations to the clock frequency, not by directly comparing it to other clocks. As a few people have pointed out, it's very difficult to measure your frequency with respect to something else when there isn't anything as accurate.> Pfff...Nothings ever good enough, huh. :)That's right! The clock will continue to improve as a methods are developed to evaluate some of the remaining sources of frequency perturbations at a higher precision. In theory, it should be possible to improve the mercury clock to the point that it wouldn't lose a second in five billion years.
fugaziJul 15, 2006
Wouldnt a sundial be the most accurate? Although you cant really tell exactly what time it would be the most accurate.
jameshalesJul 15, 2006
It is not the most accurate for measuring _intervals_ of time, as the length of a day varies throughout the year and depending on your location.Also, a sun dial stops working at night.
d4r7h3v1lJul 15, 2006
Time, Doctor Freeman? Is it really that...time... again? It seems as if you've only just arrived. You've done a great deal in a small time...span. You've done so well, in fact, that I've received some interesting offers for your services. Ordinarily I wouldn't contemplate them but, these are extraordinary times, hm? Rather than offer you the illusion of free choice, I will take the liberty of choosing for you if and when your time comes around again. I do apologize for what must seem to you an arbitrary imposition, Doctor Freeman. I trust it will all make sense to you in the course of...well...I'm really not at liberty to say. In the meantime, this is where I get off.