【150521】❤EFY❤【阅读阅开心】No.174

绝望罗勒 (布丁小葵) 资深达人
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发表于:2015-05-21 07:00 [只看楼主] [划词开启]

 

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The accuracy of scientific observations and calculations is always at the mercy of the scientist's timekeeping methods. For this reason, scientists are interested in devices that give promise of more precise timekeeping.
In their search for precision, scientists have turned to atomic clocks that depend on various vibrating atoms or molecules to supply their "ticking" .This is possible because each kind of atom or molecule has its own characteristic rate of vibration. The nitrogen atom in ammonia, for example, vibrates or "ticks" 24 billion times a second.
One such atomic clock is so accurate that it will probably lose no more than a second in 3000 years. It will be of great importance in fields such as astronomical area. Cesium is an atom that vibrates 9.2 billion times a second when heated to the temperature of boiling water.
An atomic clock that operates with an ammonia molecule may be used to check the accuracy of predictions based on Einstein's relativity theories, according to which a clock in motion and a clock at rest should keep time differently. Placed in an orbiting satellite moving at a speed of 18000 miles an hour, the clock could broadcast its time readings to a ground station, where they would be compared with the readings on a similar model. Whatever differences develop would be checked against the differences predicted.


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答题区

1、Scientists expect that the atomic clocks will be ______.
2、Implied but not stated: _______.
3、The heart of the atomichron is _______.
4、From these lection, we may assume that temperature changes_______.
5、Identical atomic clocks may be used to check______.

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