The definition of a second, the most fundamental unit oftime in our current measurement system, hasn''t been updated in more than 70 years (give or take a billionth of a second).
In the next decade or so, that might be different: Ultraprecise atomic optical clocks that depend on visible light are on track to edict the term second.
These newer versions of the atomic clock are, in theory at least, much more precise than the gold-standard cesium clock, which measures a second based on the oscillation of cesiumatomswhen exposed to microwaves.
"You can consider it as a means of having a ruler with tick marks every millimeter, rather than a stick that measures just one meter," Jeffrey Sherman, a researcher at the National Institute of Standards and Technology''s Time and Frequency Division in Boulder, Colorado, told Live Science.
The International Bureau of Weights and Measures may release the criteria for any future definition of the second in June, according to the New York Times. Bis yet, no single optical clock is quite ready for prime time.
Sherman said that a new definition might be formally approved as soon as 2030.
The new kind of optical clock might aid unmaskdark matter, the invisible substance that exerts gravitational pull, or locate remnants of the Big Bang, or gravitational waves, the ripples inspace that were established by Einstein''s relativity theory.
Fundamental unit of measure
The present standard second is based on a 1957 experiment with an isotope, or variant, of cesium. When pulsed with a specific wavelength of microwave energy, the cesium atoms are at their most "excited" level and produce the greatest possible number of photons, or units of light.
This wavelength, formerly known as the natural resonance frequency of cesium, causes the cesium atoms to "tick" 9,192,631,770 times every second.
According to the New York Times, the initial definition of a second was based on the length of a day in 1957, and this was in turn, in turn, linked to variables such as the Earth rotation and the position of other celestial objects at the time.
In contrast, optical atomic clocks measure the oscillation of molecules that "tick" much faster than cesium atoms when pulsed with light in the electromagnetic spectrum. Because they can tick much faster, they can, in theory, define a second with significantly finer resolution.
The reigning timekeeper is supplanting cesium, including strontium, ytterbium, and aluminum. Each has its advantages and disadvantages, according to Sherman.
For maximum excitations, scientists must suspend and then chill atoms to within a hair''s breadth of absolute zero, then pulse them with the precisely tuned color of visible light.
The other component of the system shines the light on the atoms, and the other monitors the oscillations.
Some of the greatest challenges arise from the use of a laser to create exactly the right light, according to Sherman.
The second step in determining the oscillations requires a so-called femtosecond laser frequency comb, which allows for small intervals to be distributed.
Both components are extraordinarily complicated engineering tasks that can take up an entire lab room on their own, according to Sherman.
Uses of optical clocks
Why do scientists want to make use of more precise atomic clocks to measure the second? It''s not just a research exercise.
Time does not move to its own drum; Einstein''s relativity theory argues that mass andgravity are being warped.
As a result, time may tick infinitesimally slower at sea level, where Earth''s gravitational field is stronger than at Mount Everest, where it is ever-so-so-slightly weaker.
Detecting these brief changes in the flow of time might also reveal evidence of new physics.
The influence of dark matter has so far been evident only in the distant swath of galaxies circling one another, from the bending of light around planets and stars, and from the leftover light from the Big Bang.
If flaws of dark matter go closer to home, then ultraprecise cameras capable of discerning the slight slowing of time might help.
As gravitational waves rock space-time, they squish and stretch time. The Laser Interferometer Gravitational-Wave Observatory, a several-thousand-mile relay race for light that measures blips in space-time caused by catastrophic events such as black hole collisions.
However, a giant of atomic clocks in space might identify thesetime dilation effects for much slower gravitational waves, such as those from the cosmic microwave background.
"They''re so-called primordial gravitational waves that might be remnants from the Big Bang," Sherman said.
Content related to this program:
Einstein''s predictions for time are confirmed through ultraprecise atomic clock experiments.
''Spooky action at a distance'' might set a realistic clock.
From the beginning of time, a new gravitational wave detector picks up a new signal.
This article was originally published by Live Science. Read the original version here.