Why seconds

So measuring a second based on rotation would mean that a second would get slowly longer over time. So, to pin down a truly timeless measure of a second, scientists in the s devised a better clock, one based not on astronomical processes but on the movement of fundamental bits of matter — atoms — whose subtle vibrations are, for all intents and purposes, locked in for eternity.

That number seems random because each and every definition of a second has by necessity been based on the one that came before.

By isolating and cooling cesium atoms to near absolute zero, researchers can measure each and every flip by the pulse of electromagnetic radiation it gives off.

It was the exact same length of time, but now, it would remain permanently fixed. In , German researchers proposed an even better atomic clock, one based on the element strontium, and which uses optical light, rather than microwave emissions for calibration. Strontium cycles much faster than cesium does, and that would make such an atomic clock even more precise by giving researchers even more data points to work with. The actual creation of such a clock is still a work in progress, and the cesium atom remains today the ultimate time keeper.

Register or Log In. Already a subscriber? Sign in. Thanks for reading Scientific American. Create your free account or Sign in to continue. See Subscription Options. Discover World-Changing Science. References Time's Pendulum. Jo Ellen Barnett. Plenum Press, A History of Mathematics. Florian Cajori. MacMillan and Co. History of the Hour. Gerhard Dohrn-van Rossum.

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See Subscription Options Already a subscriber? Create Account See Subscription Options. Continue reading with a Scientific American subscription. International Atomic Time is used as the basis for Coordinated Universal Time — which is used to set computer clocks around the world. But new technologies could change the official way we measure a second, and could be key to new communications technologies.

The optical lattice clock — using lasers and strontium atoms — is accurate to within one second every million years, and is more stable than current atomic clocks.

Optical clocks work similarly to atomic clocks, but measure the oscillations of ions or atoms which vibrate at about , times the frequency of microwave frequencies. Such clocks could provide the basis for a new official definition of the second, scientists argue. In the future, such clocks might help navigate human beings towards other planets — and even beyond, says Jun Ye of the University of Colorado Boulder. Richard Ratcliffe has issued an urgent plea to Boris Johnson to help free his wife, Nazanin Zaghari-Ratcliffe, who has been detained in Iran for over five years.

Zaghari-Ratcliffe, a British-Iranian dual national, was captured by the Iranian authorities during a family visit with her daughter in on charges of plotting to overthrow its government. The family have consistently denied the claims against her. The findings come after university students have returned to campuses across the UK for more in-person lessons and social activities.

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Deputy Speaker had Fawad dabbu thro.