The Kibble balance and the kilogram

Dr. Bryan Kibble invented the watt balance in 1975 to improve the realization of the unit for electrical current, the ampere. With the discovery of the Quantum Hall effect in 1980 by Dr. Klaus von Klitzing and in conjunction with the previously predicted Josephson effect, this mechanical apparatus could be used to measure the Planck constant h. Following a proposal by Quinn, Mills, Williams, Taylor, and Mohr, the Kibble balance can be used to realize the unit of mass, the kilogram, by fixing the numerical value of Planck's constant. In 2017, the watt balance was renamed to the Kibble balance to honor the inventor, who passed in 2016. This article explains the Kibble balance, its role in the redefinition of the unit of mass, and attempts an outlook of the future.