The Course 185 of the International School of Physics “Enrico Fermi”, Metrology and Physical Constants, was held in Varenna in July 2012, and was organized by the Italian Physical Society (SIF), the Istituto Nazionale di Ricerca Metrologica (INRIM), Torino, and the Bureau International des Poids et Mesures (BIPM). In the last twelve years international courses on Metrology were organized both in Varenna (2000, 2006, 2012) and at the BIPM (2003, 2008). The programs of the courses in Italy were developed with the participation of the BIPM, thanks to the presence of the Director pro tempore, as already occurred in the previous ones held in Varenna (1976) and in Lerici (1989). Moreover the National Metrological Laboratories have been present providing many teachers and students supported by their institutions.

Regarding the Varenna course of 2012, the international audience of PhD students, post-docs and young scientists, who could attend this course, had the opportunity to listen to the presentations of the most advanced topics of this discipline. Room has been given to topics which constitute new areas of development in metrology, such as nano-technologies, quantum information and quantum devices, biology and medicine, food, surface quality, ionizing radiations for health, environment, art and archaeology, and climate. Particular attention has been paid to the determination of the physical constants directly involved in the anticipated new definitions of the SI units of measurement, which shall be based on fixed values to be assigned to fundamental constants. This straight and direct link between fundamental physics and metrology will provide, according to our knowledge of physics, the most stable measurement system we can imagine and will eliminate the current definition of the kilogram till now based on an artefact. The “New SI” will also support a high stability level to recent measurement areas, which could be summarized by the expression “Metrology in Chemistry”. The continuous and striking advancements in basic research concerning atomic frequency standards operating in the visible range and at microwaves and the applications to satellite systems have been recalled and the problems inherent to the uncertainty statements and definitions have been reviewed. These items have been presented in the frame of a historical review of the international organization of metrology—since the Metre Convention signature—the SI development, the BIPM mission and role and the developments of the Mutual Recognition Arrangement (CIPM MRA).

Unfortunately, not all the lectures given during the course could be included in these proceedings. These presentations however were very important to complete the scientific panorama of the school and deserve to be mentioned: Steven Choquette: “Biochemical measurements methods I and II”; Kristian Helmerson: “Cold atoms, optical clocks and atom interferometers I and II”; Stephen A. Wise: “Chemical Metrology, for Environment and Human Health Assesment”.

Sponsors of this course have been the Lecco Chamber of Commerce, the National Institute of Nuclear Physics, the National Council of Research, the firm Thermo Fisher Scientific and the CRT foundation. The remarkable scientific and economic support of the INRIM must be acknowledged together with the organizing effort by SIF. Patronage has been given by the Commission A (metrology) of the Union Radio-scientifique International (URSI), the Italian National Agency for New Technologies, Energy and Sustainable Economic Development (ENEA), and the Politecnico di Torino.

The Directors wish to warmly thank all the lecturers and seminar speakers for providing the students with their expertise both during the scheduled lessons and being available for discussions. A particular feeling of gratitude must be expressed to Andrea Mario Rossi, the scientific secretary of the school, who took contacts with teachers, students and SIF before starting the course and kept contacts with the authors during the preparation of these proceedings.

Moreover the extreme valuable help and the friendly co-operation of Mrs. Barbara Alzani and Mrs. Ramona Brigatti acting on behalf of SIF must be acknowledged.

The editions of the Varenna courses on Metrology have been chances of cultural exchanges between teachers and students and among the students themselves and fruitful contacts have been maintained. The Directors hope that for many students the attendance at this Varenna school edition be a seminal point in their career development as “metrologists” and they become in the future leaders in their specific fields.

E. Bava and M. Kühne