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We do not all know the time that passes equally, the time getting closer to the gravitational pull of something massive, as the famous theorized Albert Einstein. And since gravity is usually interpreted as the way the mass deforms the space itself, it means that a sufficiently accurate atomic clock could serve as a scientific tool to measure how objects change the shape of their surrounding space. .
"We have reported measurements of two clocks that, in principle, exceed our ability to take into account (this effect) on the surface of the Earth," said Andrew Ludlow, physicist at the National Institute of Standards and Technology. of Boulder, Colorado.
Clocks are just tools for measuring the time that passes by counting a repetition, whether it is an oscillating pendulum or a vibrating atom. Optical network clocks, like those used in this study, work the same way, but not so simply.
Scientists first use lasers to create a row-shaped trapping field of cups. Thousands of ytterbium atoms populate the cups. If they are hit with an exact frequency laser, the electrons will jump between two levels of energy, an incredibly large number (almost a quadrillion), but the exact number of times per second. Once the laser is tuned to the ideal frequency to begin this oscillation, it switches to another component, called the optical frequency comb. It is essentially the gears of the clock, translating the information conveyed in the frequency of the laser light into a signal that can be used in electronics to create the ticking.
Here, researchers have essentially characterized the frequency with such a high accuracy that they can use it to accurately measure the impact of gravity over time, according to the paper published in Nature. A pair of Ytterbium optical clocks accurately indicated the transition frequency of the Ytterbium between 10 and 18 of the actual frequency, varying at most from 3.2 x 10 to 19, the difference between the frequencies of the two clocks being around 10 and 19. Clocks with this accuracy would take longer than the age of the universe (13.8 billion years) to lose a second.
But characterizing these clocks meant that ytterbium clocks could detect the temporal slowing down of Earth's gravity and accurately determine their position in the gravitational field of the Earth to within one centimeter. It's better than state-of-the-art earth-based measurement systems. Ludlow explained that the team had not yet compared the clocks in two different places. A test like this one would reveal that the high-altitude clock starts moving faster, because the gravitational pull of gravity on an object decreases slightly as it increases in altitude.
This is only the latest result of the worldwide efforts to create the best atomic clock of all time. But it's a fantastic development, said Andrei Derevianko, a theoretical physicist at the University of Nevada, Reno, who did not participate in this study, but who worked on the theory behind these clocks. He said clocks with this level of accuracy were still looking for their "killer app".
But physicists have ideas on how to use them, especially when it comes to chasing dark matter – things that our eyes and telescopes can not see directly, but that seem to exert some force of gravity in the universe. Maybe these clocks could detect dark matter in the way that its gravity changes space-time. Perhaps they can even detect ripples in space-time called gravitational waves. Or maybe it's time to move the atomic clocks into space, where they are less affected by the local gravity differences of the Earth. It's hard to say.
No, you can not wear this clock on your wrist or hang it on a wall – it's still a configuration built on a lab bench. But if you could, it would be pretty sick to be able to tell your friends that you were late because their local gravitational potential was too high.
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