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| © CNET |
By Jackson Ryan, CNET
You might not be able to fit it on your wrist, but physicists have created two clocks that are so accurate they won't lose time in the next 15 billion years.
The research, published Wednesday in Nature, describes an atomic clock that uses an optical lattice composed of laser beams trapping ytterbium atoms. Every atom has a consistent vibrational frequency, which allows physicists the opportunity to measure how the ytterbium atoms transition between two energy levels -- essentially creating the clock's "tick".
Notably, the physicists based at the National Institute of Standards and Technology (NIST) in Maryland compared two independent atomic clocks to record historical new performance benchmarks across three key measures: systematic uncertainty, stability and reproducibility.
Andrew Ludlow, project leader, explained to NIST that these three measures can be considered the "royal flush of performance" for atomic clocks. The ability to reproduce the accuracy of the ytterbium lattice clock in two independent experiments is of particular importance because it shows for the first time, according to Ludlow, that the performance of the clock is "limited by Earth's gravitational effects."
Building a machine to hunt dark matter (pictures)
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As Einstein's general theory of relativity suggests, gravity plays a fundamental role on time. Think of Interstellar's water world where each hour that passes on the planet is equivalent to seven Earth years because of its high gravity. In the case of the ytterbium lattice clock here, the vibrational frequency will change under different gravity -- the atoms would vibrate at a different rate on Interstellar's water world than they would on Earth.
And physicists can use Einstein's theory to their benefit. NIST's atomic clock becomes so sensitive that moving it further from the Earth's surface would produce a noticeable difference in how the clock "ticks". Practically, this means the clock can measure not just time... but space-time.
Cue blown minds.
With such accuracy, the clock could theoretically be used to detect cosmic phenomena such as gravitational waves or dark matter. Although we aren't quite sure just what dark matter is, provided it has effects on physical constants, it might be possible to see it.
The breakthrough marks a significant turning point for Earth too, allowing for unprecedented measurements when studying the Earth's orientation in space and its shape. If more of these clocks were scattered around the globe, the accuracy of the clock would allow measurements of Earth's shape to be resolved to within 1 centimetre -- better than any current technology.
In September, the Cryogenic Sapphire Oscillator -- or Cryoclock -- was unveiled by researchers at the University of Adelaide. That clock, which works a little differently to the optical lattice clock described today, was developed for use in radar communications. Sometimes I can't even look at my watch without being absolutely flabbergasted by the time, so I say put your hands up for the accurate clock revolution.
It's time.
