Making sense of science
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50 years ago, on October 13, 1967, the second—the unit of time—was no longer defined by stars, but by atoms. In this quest for precision, scientists are now inventing the clocks of the future,...

Time can now be measured with dizzying levels of precision, thanks in particular to contributions from the fields of optics and photonics. The quest for ultimate precision, however, is a long-term...