William D. Phillips on the Quantum Reform of the Metric System

Physicist William D. Phillips is one of the inventors of the technique of laser cooling, which allows slowing down and/or trapping atoms and molecules so they can be studied at near-rest conditions. This has allowed increasing the accuracy of atomic clocks by two orders of magnitude, reaching an accuracy of one part in 10^{16}. For this work, he shared the 1997 Nobel prize in Physics.

He is also a master explainer, and in this presentation traces the history of metrology from stone weights and lengths carved into the walls of buildings through master objects locked in a vault in Paris to the 2019 redefinition of the SI base units after which all SI units are defined in terms of fundamental constants of nature which have, to the best of our knowledge, the same values everywhere in the universe throughout its entire history.