We are delighted to introduce the proceedings of the 6th of the Enrico Fermi Summer Schools that has addressed the topic of Metrology. The school was held in Varenna from June 26th to July 6th, 2016, and was organised by the Italian Physical Society (SIF), the Bureau Internationals des Poids et Mesures (BIPM), and the Italian Istituto Nazionale di Ricerca Metrologica (INRIM).

Metrology is an active field that has developed in many ways since the first of these schools devoted to metrology was held in 1976. The successive schools have reflected these developments. The sixth one is no exception, and may in the course of time be considered to have been the one that has signalled the greatest changes.

The programme addressed two major new directions for metrology. The first was the work done in preparation for a possible re-definition of four of the base units of the SI in 2018. The main principles of the possible redefinition of the base units were explained, the challenges involved in the accurate measurement of fundamental constants were described, and attention was brought to the proposed changes in the dissemination of the units following the new definitions.

Secondly, the lectures included a deep reflection on the impact of the application of metrology to chemical measurements on science, citizens and society. The need for precise and traceable measurements in chemistry was exemplified by their application to issues addressing quality of life, global climate change, clinical and food analysis.

For the first time, the lectures were grouped into three modules held over 10 days. All students took part in a core module on the Fundamentals of Metrology. They were then able to choose to attend one or both of the optional modules that addressed: Metrology for Quality of Life and Physical Metrology and Fundamental Constants. In this way, students could choose to be part of the school for the whole 10 days, or only for 7 days according to the topics of greatest interest to them. The topics addressed in the modules were:

Module I: Metrology for Quality of Life (26th June to 29th June 2016)

Metrology in chemistry, Food supply and safety, Biomarkers, Methods and materials for clinical measurements, Climate and air quality monitoring, Redefinition of the mole.

Module II: Fundamentals of Metrology (30th June to 2nd July 2016)

The New International System of Units, Fundamental constants, Quantum metrology, Nanotechnology for metrology, Measurement uncertainty, the Organization of international metrology.

Module III: Physical Metrology and Fundamental Constants (3rd July to 6th July 2016)

Electrical metrology, the Future of the standard of mass, Temperature metrology, Optical frequency standards, Metrology in space, Photometry and light metrology.

As always, the success of a school is due to the dedication and effort of many people and institutions. Our special thanks go to:

– the lecturers who prepared their lessons and manuscripts and were available to spend time with the students, visiting their posters sessions, discussing ideas and participating in the award jury.

– the 77 students and observers who were selected from 120 applications and who created a stimulating and warm atmosphere throughout the period of the school.

– the scientific secretary, Natascia De Leo from INRIM, who devoted a lot of her time, energy, and creativity to the success of the school.

We particularly want to thank the sponsors: the Fondazione Cariplo, CalPower, FEI, Europhysics Letter, METAS, SIM, and NIST. They supported the participation of students who did not have access to sufficient funding of their own and also the best poster award which stimulated students in the clear and efficient presentation of their work.

Finally, we wish to thank Prof. Luisa Cifarelli, SIF President, for promoting the 6th edition of a school devoted to metrology, Mrs Barbara Alzani (SIF), Ramona Brigatti and Arianna Minonzio for their invaluable support in the management and organisation of the school.

P. Tavella, M.J.T. Milton and M. Inguscio