The author of the article chose the title to attract the greatest readership, not necessarily to convey accurate information...as usual.
Einstein also predicted that clocks in different gravitational fields would tick at different speeds. For example, a clock in Boulder, Colo., which is a mile above sea level, would feel a slightly weaker gravitational pull than a clock at sea level in Washington, D.C. As a result, it would tick just a bit faster — and after 200,000 years it would be a full second ahead.
That's not much of an effect, but it's big enough for most atomic clocks to measure. And Ludlow's clock can register the change in gravity across a single inch of elevation. That kind of sensitivity will allow scientists to test Einstein's theories with greater precision in the real world.
To "test" a theory to verify the theories predictions with experiments and observations. More accurate clocks can be used to verify the current predictions of, for example, general relativity, with observations that can be practically made (eg. not have to wait a significant fraction of 200,000 years for the answer). If the predictions are found to be correct within margins of error, then relativity gets one more point.
We know that general relativity and quantum mechanics as they stand today are inconsistent. Until we have an accepted theory of quantum gravity there we don't have a single theory describing behavior at the
Planck scale.
Here is some technical information about
NIST Ytterbium atomic clock:
NIST physicists report in the Aug. 22 issue of Science Express that the ytterbium clocks' tick is more stable than any other atomic clock. Stability can be thought of as how precisely the duration of each tick matches every other tick. The ytterbium clock ticks are stable to within less than two parts in 1 quintillion (1 followed by 18 zeros), roughly 10 times better than the previous best published results for other atomic clocks.
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Each of NIST's ytterbium clocks relies on about 10,000 rare-earth atoms cooled to 10 microkelvin (10 millionths of a degree above absolute zero) and trapped in an optical lattice—a series of pancake-shaped wells made of laser light. Another laser that "ticks" 518 trillion times per second provokes a transition between two energy levels in the atoms. The large number of atoms is key to the clocks' high stability.
The ticks of any atomic clock must be averaged for some period to provide the best results. One key benefit of the very high stability of the ytterbium clocks is that precise results can be achieved very quickly. For example, the current U.S. civilian time standard, the NIST-F1 cesium fountain clock, must be averaged for about 400,000 seconds (about five days) to achieve its best performance. The new ytterbium clocks achieve that same result in about one second of averaging time.
The relationship of the stability of a clock to the accuracy of the clock is evidently somewhat complex:
The ytterbium clocks' stability record is different from the performance levels previously publicized for NIST-F1, which is traceable to the international system of units, and NIST experimental optical clocks based on single ions, such as the aluminum quantum logic clock or the mercury ion clock.** NIST-F1 and the ion clocks were evaluated based on systematic uncertainty, another important metric for standard atomic clocks. NIST-F1's performance is described in terms of accuracy, which refers to how closely the clock realizes the cesium atom's known frequency, or natural vibration rate. Accuracy is crucial for time measurements that must be traced to a primary standard.
NIST scientists plan to measure the accuracy of the ytterbium clocks in the near future, and the accuracy of other high performance optical atomic clocks is under study at NIST and JILA. The research is funded in part by the Defense Advanced Research Projects Agency and the National Aeronautics and Space Administration (NASA).
My naive guess is that achievable accuracy is directly related to stability, but I could be very wrong. If so, then with Planck time being 5.39121 × 10^(−44) s there is still a lot of opportunities for interesting advances with faster, more accurate clocks and significant discoveries and verifications with each new advance.
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