问题就在于此,再加上世界各国的千克标准重量正在以不同速率变化着,这些都敦促千克单位和SI体系下其他单位一样恒定,要在纯粹参考自然界恒量的基础上定义千克。
Next year, the International Committee on Weights and Measures will discuss whether to tieit to something called Planck s constant, a number in quantum mechanics that relates theenergy level of a photon to its wavelength.
明年,国际重量与测量委员会将会讨论是否要将千克和普朗克恒量联系起来,普朗克恒量是指量子力学中联系光子能及其波长的数字。
A supersensitive electromechanical scale called a watt balance could then be used to definethe kilo with reference to Planck s constant, finally liberating the SI from its reliance onfallible artefacts.
测量极其精准的机电天平瓦特天平可以在参考普朗克恒量的基础上定义千克重量,这就使得SI再不用依赖不精确的人工制品了。
That is the theory, at least.
以上至少在理论上是成立的。
But watt balances are fiendishly complicated bits of kit.
但是瓦特天平极其复杂。
There are only a handful in the world, a situation that is unlikely to change for theforeseeable future.
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