New Atomic Clock 1000 Times More Accurate

stevelinton writes "The UK National Physical Laboratory has a new atomic clock potentially 1000 times more accurate than current cesium clocks: to within 1 second in about 30 billion years! This could lead quite soon to a new definition of the second, and in a while to improved resolution in GPS successor systems. More interestingly, there are theories that some of the universe's fundamental dimensionless constants may have changed by a parts in a million over the last 10 billion years or so. These clocks are so accurate that they should be able to detect these changes over a year or two."

Comments

Re:Accurate distance too?

[MasterC]

The length of the meter is defined by time

http://physics.nist.gov/cuu/Units/meter.html

"The meter is the length of the path travelled by light in vacuum during a time interval of 1/299 792 458 of a second."

So if you can measure time more accuractly then you can measure a meter more accurately.

Re:Accurate distance too?

[Mister Attack]

The trouble with measuring a meter this way is that it's tricky, to say the least, to know the frequency of a laser beam to high enough precision for this to be a useful measurement. You'd basically have to do exactly what these guys are doing -- cool some ions to within a few microkelvins of zero, use them as a frequency reference and lock a laser to them. Then you'd have to do it again with a different frequency. Then you'd have to actually measure the intensity of the standing wave to high enough resolution that you could get a reasonable measurement. So basically, don't hold your breath.

Much more reasonable is to keep the current definition of the meter, which is the distance that light travels in 1/299,792,458 second in a vacuum. Then your better clock gives you a more accurate length standard without all the fuss.