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Nist: New Optical Clock More Accurate Than Cesium
LordPhatal writes "NIST researchers have demonstrated a new kind of atomic clock that has the potential to be up to 1,000 times more accurate than today's best clock. The new clock is based on an energy transition in a single trapped mercury ion.
Duh! When this clock breaks the mercury will go everywhere! They already went through this phase with thermometers.
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...nursery rhyme to replace Hickory Dickory Dock:
Flappity floppity flip,
A mouse on a moebius strip,
The strip revolved,
The mouse dissolved,
In a chronodimensional skip!
:)
The NIST labs out in Boulder, CO is a fabulous place to go and visit if you ever find yourself in town, or in Denver. They will gladly take you on a tour, and show you all sorts of interesting toys that they have. Probably the best part of the tour for me was the liquid hydrogen. Even better was touching it. Yes I did, yes I still have all my digits. Basically, it is exactly the same concept as fire; move your hand thru it very quickly. In this case, touch it quickly and retract. The tour guide also shrank a balloon completely down, as we all watched, as it slowly got bigger when he took it back out. And of course on the tour, was getting to see the atomic clock. (On the other side of a window of course.) Check it out!
And if you are in Boulder, and enjoy tea, make sure to take a tour of the Celestial Seasonings Tea Plant. If you have sinus problems, their Peppermint room will take care it, pronto.
I've always wondered just how they determine how reliable a clock is.
Afterall, can't measure meters without a meterstick. Do they simply take a N Cesium clocks and average out their time to determine how close a single Mercury based clock sticks to it? Or did I miss the memo where we could acurrately time trillionths of a second?
Rod Taylor
With a cesium-133 atom, a second is the time needed for the atom to perform 9,192,631,770 complete oscillations.
--Metrollica
well, ONE single ion can only go SOMEwhere, not EVERYwhere, unless they know its momentum very precisely.
We know how long a second is. Time as we measure it is based on Earth's rotation and revolution.
What this measument is, is that it will not deteriorate over time as most methods of time measurement do currently. That is why it is so accurate. What that really means it that over time it will prove to be more accurate than anything else that we have created. A second will still be a second, and it's lenght will not change now.
"Time is long and life is short, so begin to live while you still can." -EV
The above wording is imprecise. 9,192,631,770 Hz is the frequency of the electromagnetic wave that triggers a certain transition in a cesium-133 atom. So, what oscillates is not the complete atom, but the electric and magnetic field. Details can be found here
We know how long a second is. Time as we measure it is based on Earth's rotation and revolution.
Nah we stopped doing that a long time ago. The revolution of the Earth is slowing down as the Earth sheds angular momentum to the moon. There are other relatively minor effects on the rate of the Earth's rotation. One of the ways we measure change in astronomical periods is by using incredibly accurate atomic clocks.
The original poster had a very good question: How do we define the second with such accuracy. The answer is basically: arbitrarily. In the end it doesn't matter as long as we all agree on a very accurate estimate.
As an interesting side note, even the calender is not completely determined yet. Since the number of days in a year is not a round number we have a number of rules for ammending the calender. Everyone knows about the leap year every 4 years. But this rule is skipped on years divisible by 100. The second rule is skipped on years divisible by 400. Even these adjustments are not sufficient and the interesting bit is that IIRC, noone has decided on how to handle additional corrections. The current drift rate is around 1 day in 3300 years, so if you want to book that venue for your 5000 birthday now, it will be difficult to get the date right.
Karma police, I've given all I can, it's not enough, I've given all I can, but we're still on the payroll.
One advantage of the new clock is that it ticks much faster. Today?s international time and frequency standards, such as NIST-F1, measure an atomic resonance of about 9 billion cycles per second. By contrast, the new NIST device monitors an optical frequency more than 100,000 times higher or about 1 quadrillion (US) cycles per second.
A 9 GHz oscillation can be hooked up directly to electronic circuits, counters, PLLs, etc. My first question when I read this article was, how the heck do you synchronize anything else to a "frequency" that's in the optical / ultraviolet range? I found some more information on this page and this one, so I guess that's how this new clock works.
Originally, the second was defined to be 1/86,400 of the mean solar day. Because this is inaccurate due to irregularities in the Earth's rotation, that is the length of the second would change, finer standards were chosen. These finer standards are based on the original standard, but because they are defined in another way, they will not change unless the fundamental properties of the universe do.
"The price of freedom is eternal vigilance." - Thomas Jefferson
Then you'll be measuring the flow of time in deep-space, which would be more accurate for a deep-space experiment, but less accurate for your basement experiment here on Earth.
So the best thing is to have clocks where you need them, and maybe monitor the differences between them for fun. For example, because Boulder is about 1 mile above the sea level, the atomic clock there goes slightly faster than the Washington clock.
Your suggestion of a clock in space would be a good way to define a universal time, but not a good way to gain accuracy.
I always thought a second was saying "one one-thousand" or "one Mississippi" (gotta say it quick) or "One potato". at least thats how it was back when I played 2-hand touch football. You could only blitz when you counted to five or ten using one of the above accepted methods of timing a second. But for real now, why do we need to get that much better than a bloody cesium clock? Does somebody REALLY care whether it was 9.433324545 seconds or 9.433324549 seconds? Maybe scientists? Physicists? Psychotic deranged people who wear aluminum foil body suits and 14 swatches? Enlighten me people...
Lousy facepalm.