丁香园AV

Synopsis

In November last year, the global metrology community redefined the International System of Units (the SI) in terms of physical constants of nature, opening the door to new and improved measurement science for the future. Canada鈥檚 vital contribution to this landmark decision was the work done by the National Research Council to determine the value of the Planck Constant with record-breaking precision and an uncertainty of only 9.1 parts per billion. This seminar will provide a historical perspective for the metric system, and outline the exquisite multi-national scientific effort that ended the career of the International Prototype of the Kilogram, and removed the last artefact-based definition from the SI.