New Atomic Fountain Clock Joins Elite Group That Keeps the World on Time (nist.gov) 26
NIST: Clocks on Earth are ticking a bit more regularly thanks to NIST-F4, a new atomic clock at the National Institute of Standards and Technology (NIST) campus in Boulder, Colorado. This month, NIST researchers published a journal article establishing NIST-F4 as one of the world's most accurate timekeepers. NIST has also submitted the clock for acceptance as a primary frequency standard by the International Bureau of Weights and Measures (BIPM), the body that oversees the world's time.
NIST-F4 measures an unchanging frequency in the heart of cesium atoms, the internationally agreed-upon basis for defining the second since 1967. The clock is based on a "fountain" design that represents the gold standard of accuracy in timekeeping. NIST-F4 ticks at such a steady rate that if it had started running 100 million years ago, when dinosaurs roamed, it would be off by less than a second today.
By joining a small group of similarly elite time pieces run by just 10 countries around the world, NIST-F4 makes the foundation of global time more stable and secure. At the same time, it is helping to steer the clocks NIST uses to keep official U.S. time. Distributed via radio and the internet, official U.S. time is critical for telecommunications and transportation systems, financial trading platforms, data center operations and more.
NIST-F4 measures an unchanging frequency in the heart of cesium atoms, the internationally agreed-upon basis for defining the second since 1967. The clock is based on a "fountain" design that represents the gold standard of accuracy in timekeeping. NIST-F4 ticks at such a steady rate that if it had started running 100 million years ago, when dinosaurs roamed, it would be off by less than a second today.
By joining a small group of similarly elite time pieces run by just 10 countries around the world, NIST-F4 makes the foundation of global time more stable and secure. At the same time, it is helping to steer the clocks NIST uses to keep official U.S. time. Distributed via radio and the internet, official U.S. time is critical for telecommunications and transportation systems, financial trading platforms, data center operations and more.
Nice!!! (Score:3)
Interesting time geek link to the first true atomic wristwatch.
http://leapsecond.com/pages/at... [leapsecond.com]
Atomic Wristwatch - for real? (Score:2)
Related: there are atomic clock oscillators now that are small enough to make a real but clunky atomic wristwatch.
One example, the AR50LC-10.000MHZ-SAA ($2k from digikey) is a rubidium-based oscillator that claims 0.05 parts per billion accuracy, which is in the range of seconds of drift over a human lifetime. Draws 6 watts so not a button cell battery, but definitely feasible (for low values of feasible).
I Will Stick With The Sun (Score:2)
But you do you. Since you are so smarter than the Sun.
Re:I Will Stick With The Sun (Score:4, Informative)
Fun fact: the length of the day has measurable variations (on the order of 0.001 s) throughout the year. This is due to the Earth's moment of inertia changing minutely due to higher/lower global temperatures affecting atmospheric thickness, expanding/contracting water (in liquid and solid phases, and between them), and shifting mass between the equator and poles. Seasonal changes in global wind patterns have an effect, too. [ref [nasa.gov]]
Longer term, the length of the day is changing due to the Earth gradually contracting as it cools, mass shifts from plate tectonics, tidal effects from the Moon, wobbles in the Earth's tilt, orbital perturbations from other planets, changes in mantle / outer core convection, interactions between the magnetic field and solar wind, etc. Climate change, particularly melting polar ice, is already starting to have a measurable effect. [ref [nasa.gov]] A big earthquake alone can change the length of day by 1 ms.
One millisecond may not sound like a lot, but that's 300 km at the speed of light (in a vacuum) or about 30 m in the Earth's orbital position. GPS simply would not work if our basis for the second was 1/86400 of the day. For a clock accurate down to 0.00000000000000022 s, which NIST-F4 reportedly is, 0.001 s is an eternity.
As long as DOGE doesn't screw wirh it (Score:2, Interesting)
How long until this administration kills off NIST? Any bets?
Re: (Score:2)
Re:As long as DOGE doesn't screw wirh it (Score:5, Informative)
Good news (Score:2)
Journalists ... (Score:2)
Clocks on Earth are ticking a bit more regularly thanks to NIST-F4, ...
NIST-F4 measures an unchanging frequency in the heart of cesium atoms, ...
So, the unchanging frequency is more regular? (*sigh*)
Re:Journalists ... (Score:4, Informative)
To elaborate on the other guy's comment, the second is defined in terms of "the unperturbed ground-state hyperfine transition frequency" of cesium-133, but the tricky part is measuring that accurately. https://www.nist.gov/pml/time-... [nist.gov] explains how NIST-F3 and NIST-F4 do that.
if it had started running 100 million years ago... (Score:5, Funny)
It would probably have been destroyed 35 million years later when the asteroid hit Chicxulub .
Extrapolating to millions of years (Score:2, Interesting)
if it had started running 100 million years ago, when dinosaurs roamed, it would be off by less than a second today.
This extrapolation is not valid. Sure, the match is (probably) right. But we have no way to know what external factors, over 100 million years, might affect the speed of this timekeeping method. We know, for example, that the accuracy of orbiting Cesium clocks is affected by the topography of the earth. https://www.vice.com/en/articl... [vice.com] Over 100 million years, it wouldn't take much interference from, say, passing asteroids, to potentially affect the accuracy, leading to more than a second of discrepancy at
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I think you are referring to general relativistic effects. However, I don't think we would say this reduces its accuracy - it is correctly keeping time within its reference frame.
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My issue is with the extrapolation, not the specific effect that might impact the timekeeping. If a timekeeping mechanism is shown to be extremely accurate over a period of a few years or even decades, it does not necessarily follow that it will be just as accurate over a period of millions of years. That has yet to be proven.
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We know, for example, that the accuracy of orbiting Cesium clocks is affected by the topography of the earth.
No the accuracy is not affected by gravity. The relative time differences between clocks are affected due to relativistic effects. The clock's accuracy is determined in its own reference frame when compared to that of the hyperfine transition of the caesium atom, and gravity doesn't influence this.
Just because one clock reads differently to another due to gravity and motion doesn't mean that one clock is less accurate than the other. When dealing with these kinds of precise measurements you really need to p
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While that's all true, it's kind of like saying that computers always do exactly what they are told to do. And yet, we have bugs everywhere, because what we told them to do, differs from what we expected it to do. In the case of relativistic effects on timekeeping pieces, it's true that the clocks keep time in exactly the way they experience time, and yet will end up differing from each other because of those effects. The result is that different clocks can accurately keep time, and yet not be in sync with
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it's true that the clocks keep time in exactly the way they experience time, and yet will end up differing from each other because of those effects.
The first part of this is false because a major cause of timekeeping error is errors in clocks' counting mechanisms; these errors make them not keep time in exactly the way they experience time. The second part is a red herring because serious clock people don't count relativistic effects as part of clock error.
If someone is surprised by this difference, they don't know enough to productively use a clock (or frequency reference) this accurate.
Re: (Score:2)
None of your arguments refute the fact that it's a fallacy to extrapolate accuracy over a few seconds or minutes, to millions of years.
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You haven't cited any reason to think that kind of extrapolation is a fallacy. For some time sources, long-term drift is less than you would expect from random-walk extrapolation of short-term drift. It's why a lot of NTP servers will separately specify, say, drift over both one day and one month (assuming no external inputs).
Your argument would be considerably less dumb, but still dumb, if you just argued that the accurate claim is because there is no way this clock will continue working for 100 million
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I see you're running out of arguments, since you're now resorting to insults. It's a sure sign.
I'm an engineer. As an engineer, I know that *nothing* works exactly as designed, over time. Even if you could engineer a cesium fountain clock that would run for 100 million years, it wouldn't work perfectly, without missing a beat, for that entire time. Some influence, some imperfection, would inevitably skew the timekeeping. There is no precedent for anything working flawlessly, even for relatively short period
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You're as bad at reading as you are at arguing. The first sentence of my last comment explained why you have no argument: "You haven't cited any reason to think that kind of extrapolation is a fallacy." You only assert some generic kind of experience that makes you sure. That's the real fallacy here.
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So your argument is that you are certain that over 100 million years, nothing could possibly cause variations in the timekeeping of this instrument? OK, got it. No data, just your assertion.
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That said: you're listing all kinds of perturbations that could create error - what is the supposed "true" reference that you're measuring that error against?
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I'd argue that people can't comprehend 100 million years, any more than they can comprehend a nanosecond.
Photos, please (Score:2)
If it doesn't look like a fountain, I'll be disappointed.