Scientists have a set a new record in accurate timekeeping, creating an atomic clock that won’t lose or gain a second in 15 billion years — a time span greater than the estimated age of the Universe.
The clock measures the oscillation of strontium atoms to create its tick, and could one day become the standard for the world’s official time — Coordinated Universal Time (UTC). Currently, UTC is set using atomic clocks that measure the vibrational frequency of the element caesium, although these are only accurate in the region of one second in hundreds of millions of years.
The strontium clock, developed by physicists from the National Institute of Standards and Technology (NIST) and the University of Colorado Boulder, measures the movement of strontium atoms pinned in a narrow column with powerful lasers. All atoms have naturally consistent vibrational frequency (for strontium its about 430 trillion times per second) and the measurement of these movements is used to create the clock’s tick.
THE NEW CLOCK IS SO ACCURATE THAT IT REGISTERS A DIFFERENCE IN GRAVITY OF 2CM
The strontium clock, known as an optical lattice clock, has been in development for several years and previously broke timekeeping records in 2013. However, a series of tweaks outlined in the journal Nature Communications (these include shielding the clock from types of electromagnetic radiation) have made it three times more accurate again. The clock’s so accurate, in fact, that raising it just two centimeters off the Earth’s surface has a noticeable effect, with even this minuscule change in gravity picked up by the clock’s tick.
This phenomenon is not just a matter of bragging rights though (my clock’s so accurate it notices when you put a notebook under it), but could also help scientists create incredibly accurate maps of the shape of the Earth. The effect of gravity on the passage of time was first predicted by Albert Einstein’s theory of relativity. It means, among other things, that clocks tick at different speeds at different elevations. Scientists believe that they can harness this phenomenon, using a network of incredibly accurate clocks spread across the surface of the Earth to measure its shape — a concept given the fantastic name of relativistic geodesy.
Currently though, not even the strontium clock is accurate enough to beat conventional methods of measuring the shape of the Earth (scientists suggest it would need to measure an elevational difference of just one centimeter to be useful). This means the clock’s creators will just have to be satisfied with all the other beneficial effects of more accurate timekeeping, including improving navigation and positioning systems such as GPS and pushing the boundaries of quantum physics.