ICTS

Length measurements are as old as humanity itself. Together with time and mass measurements, they have had a profound influence on all aspects of our lives, including trade, science and industrial developments. The presentation gives a survey of the development of these units, starting with an historical overview and concluding with the most recent developments where fundamental constants form the basis for units independent of space and time. In a surprising twist, the quantum Hall effect, which essentially represents a new type of electrical resistance, plays a crucial role for these modern aspects, and it may even be important for a new definition of kilogramme, the unit of mass.