The definition of a second, the most fundamental unit of time, hasn't been updated in 70 years.
Ultraprecise atomic optical clocks that rely on visible light are on their way to setting the new definition of a second.
The newer versions of the atomic clock are more precise than the gold-standard cesium clock, which measures a second when exposed to microwaves.
Jeffrey Sherman, a researcher with the National Institute of Standards and Technology's Time and Frequency Division in Boulder, Colorado, said that it is equivalent to having a ruler with tick marks every millimeter.
The criteria needed for any future definition of the second may be released in June by the International Bureau of Weights and Measures. No optical clock is ready for prime time.
Sherman said a new definition could be approved as soon as 2030.
The new type of optical clock could help find dark matter, the invisible substance that exerts gravity, or find remnants of the Big bang.
The current standard second is based on a 1957 experiment. The largest possible number of light units can be released when the cesium atoms are excited by a specific wavelength of microwave energy.
The wavelength causes the cesium atoms totick 9,192,631,770 times every second.
The initial definition of a second was tied to the length of a day in 1957, as well as variables such as the rotation of Earth and the position of other heavenly objects, according to The New York.
In contrast, optical atomic clocks measure the oscillation of atoms that are much faster than cesium atoms when they are bombarded with light. They can define a second with much better resolution because they can tick much faster.
strontium, ytterbium, and aluminum are some of the competing timekeepers. Sherman said that each has its pluses and minuses.
To achieve such a clock, researchers need to chill atoms to within a hair's breadth of absolute zero, then pulse them with the precise color of visible light needed to maximally excite the atoms.
One part of the system shines light on the atoms, while the other counts them up.
Sherman said that the biggest challenge was making sure the laser was emitting the right color of light.
The second step to count the oscillations requires a so-called femtosecond laser frequency comb, which sends light at tiny intervals.
Sherman said that both elements can take up an entire lab room on their own.
Scientists want atomic clocks to measure the second. It is not just an academic exercise.
Einstein says that time is warped by mass and gravity.
Time may tick infinitely more slowly at sea level than at the top of Mount Everest due to the fact that Earth's gravity is stronger at sea level.
New physics could be revealed by detecting minute changes in the flow of time.
The influence of dark matter has so far been only detected in the distant dance of galaxies circling one another, from the bending of light around planets and stars, and from the leftover light from the Big Bang.
If clumps of dark matter are closer to home, then ultraprecise clocks that detect the tiny slowing of time could find them.
As the waves rock the fabric of space-time, they stretch and warp time. The Laser Interferometer Gravitational-Wave Observatory is a several-thousand-mile relay race for light that measures blips in space-time created by cataclysmic events.
A battalion of atomic clocks in space could detect the effects of time dilation on slower waves.
Sherman said that they are so-called primordial gravitational waves that might be leftover remnants from the Big bang.
There are related content.
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A clock that is nearly perfect could be created by spooky action at a distance.
The new detector picks up signals from the beginning.
The article was published by Live Science. The original article can be found here.
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