Made-in-China clock loses a second in twice the age of the universe

China has joined the global top-tier timekeeping club with a new optical clock that could help it play a leading role in redefining the second. A team, led by Pan Jianwei at the University of Science and Technology of China in Hefei, has built a strontium optical clock that would lose or gain less than one second over about 30 billion years – more than twice the age of the universe. The clock’s key parameters, known as stability and uncertainty, both surpassed the level of 10 to the power of...