Look ma, no hands!

“There's never a dull moment in timekeeping,” says Poonam Arora, senior principal scientist and head of the Indian Standard Time Metrology Division of the National Physical Laboratories (NPL) in Delhi.

- Rachel Lopez

The atomic clocks are expensive and need constant monitoring. But they're also India's pride, says Poonam Arora, head of the IST Metrology Division at NPL, Delhi.

(RAJK K RAJ / HT)

Think of her as India’s ultimate clockwatcher. Arora oversees the machines that set and maintain the most accurate time for the nation, down to the nanosecond.

So, don’t go in expecting Big Ben. The most precise timekeeping devices on the planet no longer have hands, a face or even quartz mechanisms.

“A clock is simply a combination of an oscillator and a counter,” Arora says. At NPL, caesium atoms do the oscillation inside a sealed cylinder that looks like a craft-brewery tank.

A maze of lenses on one side cool the atoms, so they're slow enough to track when they get launched into the tank. Inside, in a magnetically shielded vacuum cavity, each atom moves up and down, forming a vertical fountain, its precise resonant frequency feeding data into five separate clocks in a sealed room on the other side.

“They're monsters, these clocks,” Arora says. “They are expensive devices that need stablising and monitoring day and night. I'm often checking them at home from my laptop.”