澳门金沙游戏官网网址是多少:Perfect timing

时间:2019-03-06 14:18:01166网络整理admin

NOW there’s no excuse for being more than a million-billionth of a second late. Researchers at the US government’s National Institute of Standards and Technology in Boulder, Colorado, have created a “femtosecond” clock so accurate that it would be no more than a second out after 30 billion years. The clock counts the oscillations of a laser beam, which are held at an exact frequency by linking the laser to electrons jumping between energy levels in a mercury ion. These transitions tune the laser oscillator to “tick” 100,000 times as fast as conventional atomic clocks,