SINGAPORE, Oct 3 — Scientists in Singapore have built the world’s most accurate atomic clock, a device so precise it would take about 260 billion years to lose a single second.Developed at the Centre for Quantum Technologies (CQT) at the National University of Singapore (NUS), the clock measures the frequency of an atomic transition to 19 decimal places, with an uncertainty of just one part in 10 quintillion.The results, published in Nature on September 23, put the Singapore team ahead of leading atomic clocks developed in China and the United States.The lutetium clock is about four times as accurate as…