Base units like the metre, the second and the kilogram are used every day. And while these units seem so common, their definition is tricky. Since 20 May 2019 none of the seven base units depends anymore on something like a prototype of a kilogram or a metre but solely on natural constants. In this conversation, Nobel Laureate Bill Phillips and physicist Rainer Blatt discuss the definition of the kilogram based on the scientific achievements of the Nobel Laureates Brian D. Josephson and Klaus von Klitzing. In this conversation, both physicists will illustrate how quantum effects are used to define the kilogram, and will discuss if there is a need to redefine the base unit of time although everything seems fixed.
William D. Phillips, National Institute of Standards and Technology (NIST), Laser Cooling and Trapping Group, USA
Moderator: Rainer Blatt, Professor, University of Innsbruck, Department of Experimental Physics, Austria