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  3. Leading scientists around the world are meeting in Britain to consider a proposal that could eventually see Greenwich Mean Time

Leading scientists around the world are meeting in Britain to consider a proposal that could eventually see Greenwich Mean Time

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问题     Leading scientists around the world are meeting in Britain to consider a proposal that could eventually see Greenwich Mean Time become a footnote in history. For more than 120 yeas GMT has been the international standard for timekeeping, but it is now under threat from a new definition of time itself based not on the rotation of the Earth, but on atomic clocks.
    GMT is based on the passage of the Sun over the zero meridian line(子午线)at the Greenwich Observatory in southeast London, and became the world standard for time at a conference in Washington in 1884, France had promoted Paris Mean Time at the same conference. In 1972 it was replaced in name by Universal Coordinated Time(UTC)but that essentially remained the same as GMT, UTC is based on about 400 atomic clocks at laboratories around the world but then corrected with " leap seconds "(闰秒)to adjust itself in line with the Earth’s rotational speed, which fluctuates.
    But the tiny difference between Earth speed and atomic speed have become a problem for GPS, the globalpositioning systems and mobile phone networks on which the modern world relies.
    The meeting in London are looking at the possible effects of abandoning the leap seconds and moving fully to atomic time. That would see atomic time slowly move apart from GMT, by about one minute every 60 to 90 years, or by an hour every 600 years, and there would need to be" leap minutes " a couple of times a century to bring the two in line. British science minister David Willetts has opposed the plan by saying: " We should stick to real time as experienced by humans. Without leap seconds we will lose contact with the reality of Earth’s rotation. Eventually our midnight would happen at noon. "
    In January, the International Telecommunication Union will meet in Geneva to vote on whether to adopt the new measure, despite protests from Britain.
What is new measure of timekeeping based on?
选项
答案Atomic clocks．
解析 细节题，答案在第一段末句。
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