Scientists do not have a second, they want to change it

A second is just a second, because we defined it as such. But that may change by the end of this decade. The International Bureau of Weights and Measures (BIPM), located near Paris, is studying the definition of this key measure of time, which is used in most of the seven basic units: time, length, mass, electric current, temperature, light intensity and substance. This reconfiguration of the second will allow science and technology to move forward.


For centuries, our world has measured time based on the Earth’s rotation. From the ancient Egyptians to the Greek astronomers and Babylonians, we have constantly improved the measurement of time, increasing the accuracy to hours, minutes and later – seconds.

But as the Earth’s rotation slows and changes, our ability to track time becomes less accurate. We lost more than three hours in the 2000s alone. The irregularity of the Earth’s rotation has forced scientists to study a new way of measuring time.

In 1967, after decades of research, scientists redefined time by measuring it by measuring the motion of particles inside an atom. In particular, we have come to the resonance of the natural frequency of cesium 133. Now, officially, the second is determined by taking a fixed numerical value of the cesium frequency.

Cesium 133 is a rare metal, so it is easy to trace. A heavy atom with slow particle motion resulted in a constant and easily traceable wavelength. And it turned out to be more reliable than the ticking of a traditional watch.

With an accurate clock, we are now forcing astronomical time to catch up with more accurate atomic time by adding leap seconds as needed – two of which were added in 1972, and another is added approximately every 18 months.

Search for an improved second

Improving the clock based on the cesium atom 133 leads to improved laser capabilities of mankind. There are several dozen high-level optical atomic clocks scattered around the globe. By measuring several atoms and studying their wavelengths, scientists around the world are continuing their search for a faster atom to pinpoint the second.

Femtosecond comb lasers can now measure atoms moving faster than cesium. This offered new areas of research for researchers who are still amazed at how accurate Albert Einstein’s general theory of relativity is.

Einstein said that time moves slower when closer to the big planet, because the force of gravity is different. It turns out that this may be true to the centimeter.

In the American city of Boulder, for example, three different optical atomic clocks from different laboratories have received slightly different readings, and experts from the National Institute of Standards and Technology believe that this is due to the height of the clock relative to sea level. The higher the clock, the faster it runs.

Should I reduce the minute to 59 seconds?

Thanks to advances in lasers that track the motion of atoms, researchers will continue to study the wavelengths of atoms for their stability. The global BIPM body working on the second definition may be ready to begin discussions on a new definition a second later this decade with potential approval by 2030.

Scientists say that a more accurate reflection of the second can begin the study of dark matter and the displacement of gravitational waves – things that are definitely worth a second.

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