[time-nuts] Nature: Hyper-precise atomic clocks face off to redefine time
hmurray at megapathdsl.net
Wed Jun 3 03:18:47 EDT 2015
Nice picture: A strontium-ion optical clock housed at the National Physical
Laboratory in Teddington, UK.
Over the past decade, various laboratories have created prototype optical
atomic clocks, which use different elements such as strontium and ytterbium
that emit and absorb higher-frequency photons in the visible spectrum. This
finer slicing of time should, in principle, make them more accurate: it is
claimed that the best of these clocks gain or lose no more than one second
every 15 billion years (1E18 seconds) -- longer than the current age of the
Universe -- making them 100 times more precise than their caesium
counterparts. Optical clocks are claimed to be the best timekeepers in
existence, but the only way to verify this in practice is to compare
different models against each other and see whether they agree.
Starting on 4 June, four European laboratories will kick off this testing
process -- the National Physical Laboratory (NPL) in Teddington, UK; the
department of Time-Space Reference Systems at the Paris Observatory; the
German National Metrology Institute (PTB) in Braunschweig, Germany; and
Italy's National Institute of Metrology Research in Turin. Between them, the
labs host a variety of optical clocks that harness different elements in
different experimental set-ups.
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