2018-02-20 11:47:56


BEIJING - The cylinder-shaped black object bears no resemblance to any ordinary clock, but it is one of the most advanced timepieces ever.

It was sent to space with the Space Laboratory of China's Tiangong-2 on Thursday, becoming the first ever cold atom clock working in space.

"This clock is so accurate that it should not lose one second in 30 to 300 million years in space," says Liu Liang, professor and director of the Key Laboratory of Quantum Optics, Shanghai Institute of Optics and Fine Mechanics, Chinese Academy of Sciences.

Unlike ordinary clocks, the timekeeping device is based on atomic physics.

And unlike the most atomic clocks, this clock uses more advanced "cold atom" technology, ensuring its ultra precision.

A mechanical watch loses almost one second a day; a quartz watch loses about one second every 10 days; the hydrogen atomic clock loses about one second over millions of years; the cold atom clock exceeds all in accuracy, Liu says.

Scientists attribute its accuracy to the microgravity environment in space as well as the coldness of the atoms the clock uses.

Under microgravity conditions, the cold atoms, pushed by lasers, perform a uniform motion in a straight line. By observing their performance, scientists get more precise atomic clock signal than under the gravity conditions on Earth.

Moreover, the laser cooling technology helps to eliminate the influence of atomic thermal motion on the clock's performance.

"Though molecules and atoms can't be seen in a room, they are actually moving at high-speed, and the speed is equivalent to temperature," Liu explains.

"We use laser cooling technology to slow down the atoms to a temperature that a refrigerator could never reach, so they nearly stay still," Liu says. "By observing the almost static atoms we make our measurements more precise."

Scientists believe that putting such a clock in space will help set a time standard to synchronize other atomic clocks in space more precisely.

"A more accurate clock system in space will benefit us on Earth," Liu says, citing possible substantial improvements in navigation and positioning accuracy.

Scientists say the development of cold atom technology could also make many experiments possible, such as deep space navigation and positioning, dark matter probes, and even gravitational wave exploration.

"A lot of research is based on our measurement of time and space. If we could detect subtle changes in time and space, we could make discoveries beyond the range of existing technology," Liu says.

"In the future, there will be more accurate clocks than this cold atom clock and our ultimate goal is to make a clock that will never be a second fast or slow over the life of the universe."



地下管廊概念龙头股China's naval chief told a visiting US Navy officer on Monday that Beijing "will never give up halfway" the construction of its islands in the South China Sea.

时间倒回到上个世纪50年代,那时的沅水沿岸,由于山水阻隔,交通闭塞,一直处于贫困落后的状态。基本信息项目1数据1项目2数据2股票代码603823股票简称百 合 花申购代码732823发行价10.60元发行市盈率22.08倍参考行业市盈率-申购日期2016.12.07网上发行数量2400万股总发行数量6000.00万股申购股数上限22000股顶格申购需配市值22万元中签号公布及缴款日2016.12.08公司简介及募投项目项目投资金额(万元)补充流动资金项目8600.00年产8000吨高性能与环保型有机颜料项目34529.75主要财务指标财务指标/时间2015年2014年2013年2012年总资产(亿元)14.34014.01014.20013.170净资产(亿元)7.3906.2905.1904.150营业收入(亿元)11.56012.68011.80011.280净利润(亿元)1.3001.1801.0900.880资本公积(亿元)0.430未分配利润(亿元)3.5202.5701.6700.820基本每股收益(元)0.7200.6500.6000.490稀释每股收益(元)0.7200.6500.6000.490每股经营现金流(元)0.3900.6000.9200.620净资产收益率(加权,%)23.30025.65030.040-当日,甘肃省公路航空投资集团有限公司在香港联合交易所成功发行了为期3年总额为5亿美元的债券。



"It requires strong leadership to clean up the problems left behind by those officials who are now under investigation," said Fu Siming, a professor of administrative law at the Party School of the CPC Central Committee.

地下管廊概念龙头股Xi commends launch of world's largest radio telescope in China

地下管廊概念龙头股The climax of the day came from the national women's volleyball team, whose members shared their triumphs and showed their skills amid wild cheers. Even swimmer Sun Yang, whose parents are professional volleyball players, demonstrated his volleyball talents.

根据保监会向前海人寿下发的第二次监管函来看,此次前海人寿万能险新业务被叫停,是因为在前海人寿上报的整改报告中,未对检查发现的万能险管理问题整改到位,其万能账户仍未按监管要求进行单独管理。沈阳市公安局大东分局值班室 88503258(责任编辑: HN666)英国贸易数据统计现重大错误 大幅下调经常帐赤字 国家统计局(ONS)6日大幅下调了对该国贸易和经常帐赤字的统计数据,因此前其发现在贸易统计上出现“处理错误”。


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By XU WEI (China Daily) Updated: 2016-01-29 08:06地下管廊概念龙头股In 1921, the Party had a mere 50 members, but now it has more than 88 million, resulting in higher standards and more applicants from a wide range of backgrounds. Peng Yining reports.




An elderly woman walks in a residential community in Beijing. [Photo/IC]

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