...for a second at the dawn of the New Year, as the world’s most accurate clocks synchronise with the earth’s rotation. India’s timekeeper, the National Physical Laboratory, will tune its atomic clocks too.

Clocks are machines of whimsy. Every timepiece has a personality and a character of its own—and we are not talking about mother-of-pearl Rolexes and titanium Tissots here. Synchronise all the clocks in your house today and a year later, some will have fallen behind and some zipped ahead by a few seconds. Unless, of course, they happen to be cesium atomic clocks.

“Once synchronised, a cesium atomic clock—which harnesses the transition of electron energy levels in cesium atoms to measure time accurately—won’t miss a second in 10,000 years. It is far superior to a quartz clock, which needs tuning every few months,” says Dr P. Banerjee, head of the Time and Frequency Section at the National Physical Laboratory (NPL) in Delhi. The keeper of Indian Standard Time (IST), NPL has five such atomic clocks, “just to be sure”. Ironically, for a machine that seeks to tame the cosmic continuity of time—something that cannot be apprehended by physical senses—by gauging it down to the nanosecond, a cesium atomic clock typically has a life span of less than a decade. “It is an electronic instrument; it may fail any time,” says Dr Banerjee. In fact, one of the five clocks at NPL has just been returned to the grid after being shipped to the US for repairs.

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