As of 20 May 2019, the unit of the kilogram will no longer rely on an unstable artefact guarded in a triple locked vault in Paris, but on the invariability of Planck’s constant h. Similarly, three other base units, the kelvin, the ampere and the mole will be redefined in terms of fundamental constants. This presentation will describe how we have reached this point and why, and what it means for the future. One advantage of using fundamental constants to define our units is that any physical relationship that relies on that constant can be used to realise the unit. This will be illustrated by looking at how several equations of state have been used to define Boltzmann’s constant and can now be used to realise the kelvin.
Presented by Peter Saunders- Distinguished Scientist, Measurement Standards Laboratory of New Zealand on May 20th in Christchurch. This is a joint event between the NZIC and the NZIP. Please register for this talk here.