Time is an ancient and contrary mystery. Augustine of Hippo, writing his Confessions in a North African monastery, asked “Who can even in thought comprehend it, so as to utter a word about it? But what in discourse do we mention more familiarly and knowingly, than time?”
More than 16 centuries later, many scholars share the feeling, if not the prospect of sainthood. “We don’t even know what time is. But we can measure it really, really well,” says Chris Oates, a physicist at the National Institute of Standards and Technology’s Boulder, Colo., campus.
His team operates a ytterbium optical lattice clock, one of the latest types of souped-up atomic timepieces. To track the passing seconds, such clocks rely on the fixed frequencies of photons absorbed and emitted by atoms’ electrons as they change energy levels. Recently, scientists have found ways to make these quantum counters even better, by switching from a reliance on microwave frequencies to the faster-paced optical regime and introducing a system of checks that relies on multiple atoms in levitated grids. In a remarkable recent development, the central atomic metronomes are protected from distortion by a method so powerful that physicists formally call it magic.