Slashdot Mirror
Keeping Time with a Mercury Atom
Roland Piquepaille writes "The National Institute of Standards and Technology (NIST) has announced that a new experimental atomic clock based on a single mercury atom is now at least five times more precise than NIST-F1, the U.S. standard clock. This mercury atomic clock 'would neither gain nor lose a second in about 400 million years' while it would take 'only' 70 million years to NIST-F1, based on a 'fountain' of cesium atoms, to gain or lose a second. But even if this new kind of optical atomic clock is more accurate than cesium microwave clocks, it will take a while before such a design can be accepted as an international standard. A ZDNet summary contains pictures and more details about the world's most precise clock."
syncing to time.singlemercuryatom.nist.gov doesn't work yet.
?giS
It's easy to make impressive statements like that when you know nobody will be around to prove you wrong!
bite my glorious golden ass.
Great news for those mission critical D-Link routers!
They're treating time as if it were something absolute.
Visit http://ringbreak.dnd.utwente.nl/~mrjb/growingbettersoftware to download your free copy of the book
So... at what point do you say that a clock is accurate enough? I mean, yeah maybe this thing is more accurate than current technology, but if it turns out to be way more expensive, why bother? How often do you need the accuracy that current technology can't provide?
DRM 'manages access' in the same way that a prison 'manages freedom'
Can someone explain why we even need this sort of precision?
Duct tape is like the Force. It has a light side, a dark side, and it holds the universe together.
the isotope you mention (194) is synthetic anyways
...from the Heisenberg uncertainly principle:
The more precisely
the MOMENTUM is determined,
the less precisely
the POSITION is known
So this clock is unfortunately missing. And when it is found, it is not so accurate anymore.
"Fix it"
400 million years in the future, my descendents will profit unthinkable amounts from their ownership of y400002k.com
Just in case the religious right get a further hold on our country in the future, I've also registered jesuswillreturn400002k.com and (hedging my bets) spaghettimonsterwillreturn400002k.com
but we all know that by that time, humanity will simply be slaves to the powerfully accurate mercury clock.
So, I for one welcome our new mercury atom overlords, and remind them that mercyatomoverlords.com can be had for the steal of 6.7 billion dollars, should cover the cost of registering the domain up to that point.
www.GrenadeHop.com
Fit on my wrist??????????
I'm just curious about something here. If a second is defined to be 9,192,631,770 oscillations of a Caesium-133 atom, then why is it said atomic clocks are accurate to within a second over 70 million years? Isn't that lost/gained second itself defined by the Caesium atom's transitions? I hope this question makes sense...
--- At my sig, unleash hell.
At what point do people simply say that our time keeping methods are good enough?
We already have a clock that only loses 1 second every 70 million years! The odds of the current time keeping system (or mankind, for that matter) continuing in it's current form for the next 70 million years are rather low, so why do we really need one that only loses a second every 400 million?
Sure, it's nice to be able to improve, but can't the research money go to something more useful? Like, maybe cancer research or studies into how we can build giant robots that transform into dinosaurs...
Actually, the logical design of the clock will last 40 billion years until it produces an error. I'm quite sure we will never design any sort of mechanical device can actually last that long to find out.
//unless you socket it with a zod rune...
I'm suspecting that this level of accuracy would be quite useful in high-end scientific experiements--not so much for general wall-clock settings.
For example, measuring the duration of extremely short events--like in particle accelerators.
- The race is not [always] to the swift, nor the battle to the strong. -
http://en.wikipedia.org/wiki/Clock_of_the_Long_Now
-John Fenley
Can't wait to have a wristwatch with this. My atomic wristwatch is a bit too bulky.
Open Source Alternatives
- At an accuracy of 10^-17, the earths gravity makes that two identical clocks, one of which is 5cm higher up than the other one, will start deviating from each other (i.e. time really IS different 5 cm up, at this accuracy)
- At an accuracy for 10^-17, relativistic effects start playing a role at walking speeds (i.e. time really IS different at walking speed than at rest, at this accuracy).
I think 5cm and 5km/hour are reasonable usability limits, hence an accuracy of better than 1:10^17 would not make much sense to me.The clock is based on mercury-199. Yes, it's a stable isotope.
The 400-million year figure is still limited by technical issues, not fundamental physics. It is expected that once a few more calibration methods are tried out, that it will be able to reach its theoretical limit, which actually does turn out to be pretty close to one second in five billion years. In any case, these millions-of-years figures are not really practical-- they're just the way that clock people phrase things so that they sound good in the popular press. What really matters is that the precision that can be obtained in a much shorter period of time is much higher. Right now the mercury clock has errors at the level of about a second in 400 million years-- but a second is a lot of timing error! Perhaps a more useful (but equivalent) figure would be 2.3 ns per year, or perhaps you would rather use 44 picoseconds per week.
To add a more practical real world example to this line of thought....
Clock accuracy is one of the key components of GPS systems and other navigational equipment. By having a much more accurate clock, you would be able to build devices that can determine with higher precision exactly where you are on the Earth... or for that matter in space even.
If you aren't aware of the "data" that is streamed out of GPS satellites, all that is transmitted is a clock signal that simply says what time it is right now, and along with some identification information. When compared to other satellites and applying some fairly straight-forward mathmatics (that includes some relativity equations), you get your current position.
In fact, while you might be able to determine within about 20 feet where you are at with current GPS technology and think that is "good enough" for the purposes of using that technology, navigation in the Solar System is going to need even higher clock accuracy in order to plot accurate trajectories to Mars and not get the current 30% failure rate of spacecraft trying to get there and accidentally crashing into the surface or other navigational mistakes caused by inaccurate plotting of the motion of both Mars and the Earth.
In short, you life someday (perhaps even now) might litterally depend on the navigation equipment of the vehicle you are in (read airliner) knowing precisely where you are at, and a more accurate clock will give that vehicle better accuracy to keep you alive.
I know I'm risking my own karma to ask this, but why was parent modded Redundant? The comment is funny, and it accurately illustrates why we might take time to do something seemingly useless. Because it might be useful, duh!
Point is - parent should be modded up/funny. If I had mod points today I'd do it myself.
So you can laugh all you want to...
His blog IS what he describes as "ZDNet's summary". The same link he spams in every one of his submissions.