E起計量打基礎 No. 27_科學家針對1875年肇始的SI國際單位制(米制)的改造將做出投票決定

E起計量打基礎 No. 27_科學家針對1875年肇始的SI國際單位制(米制)的改造將做出投票決定1

E起計量打基礎 By 周隆亨 (Henry Chow)

科學家針對1875年肇始的SI國際單位制(米制)的改造將做出投票決定 No. 27_20181106

科學家將在本月16日在巴黎舉行的國際度量衡大會(CGPM)上投票，針對國際單位制(SI units)的改造與重新定義做出最後的決定。

經過數十年突破性的實驗室的研究工作，全世界的科學技術社群正在迎接SI國際單位制的七個基本單位中的四個單位重新定義時刻的到來。即將到來的2018年11月16日在巴黎的CGPM大會上投票將決議通過這項劃時代的改變。這個同意票決意謂著：質量的單位公斤、溫度的單位克耳文、電流的單位安培與物量的單位莫耳之後將由自然的基本常數而非物理上的實體來決定與定義。這個歷史上的改變是自從1875年米制公約簽署以來，在國際計量領域社群最大的單一項的轉變。科學家期待這項轉變可以激發人類對於技術的創新，同時降低許多高科技在製造製程上的成本。

有關更多SI改變細節可參考所連結的影音錄像檔1。

The Future2

The world has reached a point at which the seven redefined SI base units can now be transformed from definition to practical reality without the need for any type of artifact such as Le Grand K.

The revised SI will redefine the kilogram using a fixed value for the Planck constant and using the definition of the meter and second, which are already based on constants.

This single change to the definition of the kilogram will democratize precision measurement by making it possible to do more accurate and precise measurement science anywhere in the world (and even the universe), without needing calibration to a specific artifact. With this system, should E.T. or Alf come knocking, we would be able to communicate the base units to residents of other planets in other galaxies, who could use them with the same accuracy as we do.

The immediate effect of this change will not be noticed by consumers in the marketplace. A kilogram of sliced turkey at the deli counter will still be the same amount of turkey as far as your grocery scale is concerned.

The biggest expected change will likely be for manufacturers of scientific instruments, some of whom may need to adapt their products in coming years to accommodate the revised SI method for better determining measures of electric quantities such as the ampere, the volt and the ohm.

Another key benefit of the redefined SI will be improved scalability for measurements. When you use physical objects to measure things, accuracy decreases at sizes much smaller or larger than your standard. A pharmaceutical company, for example, may need to measure chemicals for research on new drugs in quantities that are a million times smaller than a standard kilogram. The new definition of the kilogram will allow much better measurements of these milligram and microgram masses.

The revised SI is set to be implemented on May 20, 2019. If implemented as expected, all measures of mass — whether an eyelash or an airplane — could, if measured with the same technology, be equally accurate and precise.

What new discoveries will the revised SI enable? Can adding a few additional decimal points to the end of measurements that are already exceedingly precise make a difference?

The answers? It’s difficult to know but it’s a safe bet. Every time humanity has increased the accuracy and precision of measurements, better technologies have resulted.

If history is any indication of the future, the revised SI is likely to help solve a wide range of mysteries. We need only to make the change and watch while the innovation unfolds.

Created May 12, 2018, Updated November 05, 2018

Ref: 1) Scientists to Vote on Metric Makeover – English Full, NIST, November 6, 2018. (https://www.nist.gov/video/scientists-vote-metric-makeover-english-full?fbclid=IwAR0Fzn0ZezAD0f5Mi9G4b7ba1olZ6ZK9O5wCGQbRKTXnc-ugJLkZ29NpqdM )

2) A Turning Point for Humanity: Redefining the World’s Measurement System, NIST, November 5, 2018. (www.nist.gov/si-redefinition/turning-point-humanity-redefining-worlds-measurement-system )