Tom O’Brian is the Chief of the National Institute of Standards and Technology’s (NIST’s) Quantum Physics Division (QPD). O’Brian oversees America’s master clock. In an interview with NPR, he discusses what the future of atomic clocks is going to be. A bit mind-bending:
Right now, on the top of Mount Everest, time is passing just a little bit faster than it is in Death Valley. That’s because speed at which time passes depends on the strength of gravity. Einstein himself discovered this dependence as part of his theory of relativity, and it is a very real effect.
The relative nature of time isn’t just something seen in the extreme. If you take a clock off the floor, and hang it on the wall, Ye says, “the time will speed up by about one part in 1016.”
That is a sliver of a second. But this isn’t some effect of gravity on the clock’s machinery. Time itself is flowing more quickly on the wall than on the floor. These differences didn’t really matter until now. But this new clock is so sensitive, little changes in height throw it way off. Lift it just a couple of centimeters, Ye says, “and you will start to see that difference.”
So, this new clock would be able to sense the pace of time speeding up as it moves inch by inch away from the earth’s core.
What’s the point of having such high precision clocks? The extreme level of sensitivity to gravity might allow scientists to map the interior of Earth or help scientists find water and other resources underground.