Keeping Time with a Mercury Atom 153
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."
Re:One small problem... (Score:4, Informative)
the isotope you mention (194) is synthetic anyways
Re:How much accuracy do you need? (Score:4, Informative)
Re:400 million years (Score:5, Informative)
The same way they've been doing it for many years with current atomic clocks... You don't just have a single clock, you have a BANK of numerous atomic clocks, and use statistical sampling to correct drift. And establish a very, very accturate time base.
Re:How accurate is accurate enough? (Score:3, Informative)
Re:I Know I'm Missing Something Here... (Score:5, Informative)
An example of the problem is this: for technical reasons, a small magnetic field is needed inside a cesium clock. Magnetic fields change the spacing between all atomic energy levels to some degree. For cesium, the relevant change is very small, but it is still there. What you need to do is measure the magnetic field, calculate how much it affects the frequency of the atomic transition, and correct your output frequency by the required amount. What ultimately sets the accuracy level of a given clock is how well the magnetic field shift (and dozens of others) can be corrected for.
The same is true for the mercury clock. The difference is that the systematic frequency shifts that can affect accuracy of the clock are now understood, and controllable, at a higher level of precision.
Re:Why? (Score:3, Informative)
--
BMO
Re:Missing the point (Score:3, Informative)
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.
Re:Closed Season (Score:3, Informative)
His blog IS what he describes as "ZDNet's summary". The same link he spams in every one of his submissions.
Re:400 million years (Score:3, Informative)