Need the time? How about to the closest hundred trillionth of a second? No problem! Because this, officially now the world's most accurate clock, can tell the time more accurately than any other device ever has.
Fuelled by the rather exotic element ytterbium, the clock is stable to one part in a quintillion. Like the pendulum of a clock can take a fraction longer to swing on occasion, so an atomic clock can throw up an incongruous period of time, too — but you'd have to wait a quintillion ticks before that happened with this clock. Andrew Ludlow of the US National Institute of Standards and Technology explains what the accuracy means in real terms:
"We've reached a new level, an order of magnitude improvement over what had been done before. If you were to run this clock for around 100 million years, it would only gain or lose about a second."
So how the hell do you make a clock so accurate? New Scientist explains:
To create each clock, the team cooled 10,000 ytterbium atoms to 10 millikelvin, or 10 thousandths of a degree above absolute zero, and used a series of lasers to trap them in a sort of egg carton of light. Another laser, called the "clock" laser, provoked a transition between two of the atoms' energy levels... The team used an extremely steady laser to reduce jitter in the atoms, and thousands of atoms to average out any disturbances that could have knocked individual atoms off their cycles.
And the accuracy isn't going to waste, either: there are plans afoot to use the device to test Einstein's theory of relativity to 10 parts per billion. That's an unprecedented level of accuracy — so let's see if Albert's theory holds up to such scrutiny. [Science via New Scientist]