The measure of all things: redefinition of the kilogram, the kelvin, the ampere and the mole

Redefinition of the SI Units
Friday, March 29, 2019 - 15:30 to 16:30
John Hume Lecture Theatre 2

Dr. Bajram Zeqiri

National Physical Laboratory, UK

Abstract: Measurement lies at the heart of all science and engineering with progress in these disciplines often linked to advances in the science of measurement (metrology). If we cannot measure something then we cannot begin to understand it or improve it. Better measurement therefore leads to better understanding and control. Measurement itself is the quantitative comparison of an unknown quantity with a standard. In the International System of Units – the ‘SI’ System – there are seven standard quantities which are called ‘base units’: the second, metre, kilogram, ampere, kelvin, candela and mole. The perfection to which these definitions can be made real represents a fundamental limit to achievable measurement uncertainty. In order to remove these limits, from May 2019 there will be subtle but profound changes in the definitions of four of these base units – the kilogram, ampere, kelvin and mole.  This talk will explain the rationale for the forthcoming changes and why, even though you are unlikely to personally or professionally notice any changes, you should be happy about them.

Joint seminar with Experimental Physics, Theoretical Physics and Chemistry

Sponsored by the National Physical Laboratory and the Institute of Physics in Ireland