Ultra-precise atomic optical clock redefines the length of a second

The more detailed detection of small changes in the flow of time could help scientists uncover new physical evidence.

How long is a second?

The definition of the second - the most basic unit of time in our current system of time measurement has not been updated in more than 70 years. Accordingly, the current standard for seconds is based on a 1957 experiment with an isotope, or variant, of cesium (the chemical element on the periodic table with symbol Cs and atomic number 55) in the state the most "excited" and release the largest possible number of photons or units of light.

When measuring again the wavelength - what is known as the natural resonant frequency of cesium, the scientists discovered that the cesium atoms "tick" 9,192,631,770 times per second. Since then, the length of the second has been determined.

Prague Astronomical Clock (Praha Orloj) - one of the oldest clocks in the world, located in the Czech Republic

But over the next decade or so, this definition could change. Based on technology called super-accurate atomic optical clocks, scientists can now rely on visible light to establish a new definition of the second.

In theory, this atomic clock would be much more accurate than standard cesium clocks, once known for their ability to measure seconds based on the oscillations of cesium atoms when exposed to microwaves.

To better understand this difference, Jeffrey Sherman, a researcher at the National Institute of Standards and Technology for Time and Frequency in Boulder, Colorado (USA) used an interesting comparison. "Imagine like before, we measure the second with a 1-meter stick," Sherman said. "But now you'll have a ruler with millimeter markings."

To do this, the researchers had to split, then cool the atoms to absolute zero in a hair, and then "overclock" them to magnetically-corrected colors of visible light. required for maximum excitation of these atoms. Finally, they will count oscillations from light pulses emitted from very small distances, to measure the "length" of a second. These are all extremely complex techniques and may require more experiments to measure accurately.

However, if all goes to plan, Sherman believes a new definition of the clock second could be officially adopted by 2030.

Why re-measure the seconds?

Time is not simply transmitted in a straight line

Time is not simply transmitted in a straight line. Einstein's theory of relativity used to suggest that it was deformed by mass and gravity. As a result, time can pass a little slower at sea level, where Earth's gravitational field is stronger than at a very high location, such as on Mount Everest.

According to Sherman, the more detailed detection of small changes in the flow of time not only helps to redefine concepts to make them clearer, more precise, but can also help scientists figure out entirely new physical evidence.

In addition, the new type of optical clock could help detect dark matter, the invisible substance that generates gravity, or look for "Big Bang" remnants in the form of gravitational waves - or ripples in space-time, predicted by Einstein's theory of relativity.

It is known that the extent of dark matter influence has only been detected in distant regions, where galaxies orbit each other, from the bending of light around planets and stars, or from light left over from the Big Bang.

However, if these clumps of dark matter are lurking somewhere closer, even right here on Earth, then super-accurate clocks that can detect tiny delays in time. space - is the most likely thing that could help scientists find them.