While time is eternal, the way human’s measure it is an arbitrary construct. However, it’s perhaps the most important arbitrary construct in our lives determining everything from when we plant crops, when we arrive and work and when we’re allowed to drive a car. It’s a good thing, then, that researchers at the National Institute of Standards and Technology (NIST) have developed a clock that will remain deadly accurate long after the human population has gone extinct.
Called the strontium atomic clock, the latest modification means that the device will neither lose nor gain even one second over the span of 15 billion years. That, for those keeping score, is about the estimated age of the entire universe.
The JILA/NIST clock is a complicated device. It gets its name from the thousands of strontium atoms contained within a column of laser light called the optical lattice. The clock works by bathing the atoms in a laser at the precise frequency that causes them to oscillate between two electronic energy levels. The “ticks” are then measured at a rate of 430 trillion per second.
Obviously, a super-precise clock has plenty of timekeeping applications. But with something so incredibly accurate, scientists are looking beyond timekeeping. The clock is so accurate that the technology could detect even minor changes in gravity. That could be huge for airplanes, for instance.
“Our performance means that we can measure the gravitational shift when you raise the clock just 2 centimeters on the Earth’s surface,” JILA/NIST Fellow Jun Ye says. “I think we are getting really close to being useful for relativistic geodesy.”
Coincidentally, their findings prove the parts of Einstein’s theories of relativity that suggested clocks tick faster at higher altitudes. Relativistic geodesy refers to using a network of such clocks to make 3D measurements of Earth’s shape. They would be far more accurate than current technologies, like tidal gauges.
Other updates include a radiation shield, which makes the clock much more useful in real-world environments.
“The clock operates at normal room temperature,” Ye notes. “This is actually one of the strongest points of our approach, in that we can operate the clock in a simple and normal configuration while keeping the blackbody radiation shift uncertainty at a minimum.”