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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
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
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"
Complete nonsense. This isn't a "prediction", it's a mathematical number/time. Like any other number/time, you can easily convert it into shorter time-frames.
1 sec in 400 million years is ==
1/2 sec in 200 million years
1/4 sec in 100 million years
1/8 sec in 50 million years
etc.
That means it is accurate to 0.000000025ths of a second in 10 years... A more partical time-frame, which can be tested fairly easily.
Slashdot gets worse every day... Pipedot: News for nerds, without the corporate slant
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.
Slashdot gets worse every day... Pipedot: News for nerds, without the corporate slant
- 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.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.
This man begs to differ.