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Find the resulting unit of measure. If a second was defined in terms of strontium, the equivalent SI unit would be about , billion cycles. This method of calculating the length of a second reduces the error to less than 0. Optical clocks, which use lasers to monitor atoms or ions in a vacuum chamber shielded from outside influences, have been known about for some time but have been plagued with problems because they are so technically complicated and have a tendency to stop working.
Dr Grebing said their method showed they could be made to work in a practically useful way, but added that formally redefining the length of a second should be delayed for perhaps another 10 years. This would allow time — even if measured by inferior caesium atoms — for scientists to work out which optical clocks were the most accurate. Other rival versions use different elements, such as aluminium atoms and ions, instead of strontium. If the length of a second was redefined, the idea would be to make it as close as possible to the current second, but it would be likely to produce a tiny change, he added.
Join thought-provoking conversations, follow other Independent readers and see their replies. We should not be accumulating leap seconds so that that is no longer true. Leap seconds are far from the only ongoing uncertainty about time.
The current definition of a second, 9,,, periods of a maser that will cause cesium to transition, isn't perfect. For one thing, the duration of a second, as currently defined, is slightly different at altitude compared to sea level due to general relativity, so corrections need to be made. It could be more accurate, and as a matter of fact, we have clocks that are more accurate. These optical clocks , as they are called, work similarly to cesium fountain clocks.
However, instead of levitating a ball atoms, they simply trap those atoms in place in a chamber with a system of lasers and then use one specific laser to cause them to transition. The difference is in the frequency.
A laser in the visible spectrum has a frequency that is around ten thousand times higher than the 9,,, Hz maser. A definition for the second based on an optical clock would therefore be counted as some 90 trillion periods of radiation, sometimes called "ticks," rather than 9 billion, as it is now. And then if you walk to the hall over there, those guys will be like no it's aluminum ions. Unless of course you go to the room next door, at which point it's mercury ions, I'll tell you it's mercury ions!
Additionally, lawmakers, who Jefferts says often have trouble grasping the definition of the second in the first place, are unlikely to change the standard unless they have a practical reason. If there is a financial incentive, or a need to make computers more accurate, for example, the official definition of a second could be changed to an optical clock measurement.
But whether that will happen in our lifetimes is unknown. Until then, like Jefferts, you might just want to memorize the number 9,,,, lest you lose track of the time. Type keyword s to search. Today's Top Stories. If only the real world were so simple. America's Top Time Lab. The cylinder at the top contains the cloud of cesium atoms that are elevated using laser energy, and the optics table it is mounted on uses a suite of instruments to redirect and change the properties of the lasers.
Jay Bennett. This content is imported from YouTube. You may be able to find the same content in another format, or you may be able to find more information, at their web site. A note from Steve Jefferts in the F1 lab. A small fountain clock of rubidium. The rubidium, like the cesium in the larger F1, is contained in a glass ampoule that is inside the copper tube you can see on the side of the clock.
To release the atoms, horologists simply crush the tube with a pair of pliers, and then adjust the temperature to control how many of the atoms become gaseous. A ytterbium optical clock at NIST. This content is created and maintained by a third party, and imported onto this page to help users provide their email addresses.
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