The reliability and accuracy of systems of measurement continue to advance. We are about to enter a period of the most stable measurement system we can imagine with the anticipated new definitions of the SI units of measurement; a direct link between fundamental physics and metrology which will eliminate the current definition of the kilogram, until now based upon an artifact. This book presents selected papers from Course 185 of the Enrico Fermi International School of Physics, held in Varenna, Italy, in July 2012 and jointly organized with the Bureau International des Poids et Mesures (BIPM). The papers delivered at the school covered some of the most advanced topics in the discipline of metrology, including nano-technologies; quantum information and quantum devices; biology and medicine; food; surface quality; ionising radiation for health, environment, art and archaeology; and climate. The continuous and striking advances in basic research concerning atomic frequency standards operating both in the visible range and at microwave levels and the applications to satellite systems are also considered, in the framework of a historical review of the international organization of metrology, as are the problems inherent in uncertainty statements and definitions. This book will be of interest to all those whose work involves scientific measurement at the highest levels of accuracy.

The object of this NATO Advanced Study Institute was to pre sent a tutorial 'introduction both to the basic physics of recent spectacular advances achieved in the field of metrology and to the determination of fundamental physical constants. When humans began to qualify their description of natural phenomena, metrology, the science of measurement, developed along side geometry and mathematics. However, flam antiquity to modern times, the role of metrology was mostly restricted to the need of commercial, social or scientific transactions of local or at most national scope. Beginning with the Renaissance, and particularly in western Europe during the last century, metrology rapidly developed an international character as a result of growing needs for more accurate measurements and common standards in the emerging indus trial society. Although the concerns of metrology are deeply rooted to fundamental sciences, it was, until recently, perceived by much of the scientific community as mostly custodial in character.

Proceedings of the NATO Advanced Study Institute, Erice, Italy, May 2-12, 1987

One of the exciting characteristics of metrology is its intimate relationship between fundamental physics and the leading edge of technology which is needed to perform advanced and challenging experiments and measurements. This title includes a set of lectures which present the relevant progress in Metrology.

Reality as we know it is bound by a set of constants—numbers and values that dictate the strengths of forces like gravity, the speed of light, and the masses of elementary particles. In The Constants of Nature, Cambridge Professor and bestselling author John D.Barrow takes us on an exploration of these governing principles. Drawing on physicists such as Einstein and Planck, Barrow illustrates with stunning clarity our dependence on the steadfastness of these principles. But he also suggests that the basic forces may have been radically different during the universe’s infancy, and suggests that they may continue a deeply hidden evolution. Perhaps most tantalizingly, Barrow theorizes about the realities that might one day be found in a universe with different parameters than our own.

Metrology is a constantly evolving field, and one which has developed in many ways in the last four decades. This book presents the proceedings of the Enrico Fermi Summer School on the topic of Metrology, held in Varenna, Italy, from 26 June to 6 July 2017. This was the 6th Enrico Fermi summer school devoted to metrology, the first having been held in 1976. The 2017 program addressed two major new directions for metrology: the work done in preparation for a possible re-definition of four of the base units of the SI in 2018, and the impact of the application of metrology to issues addressing quality of life – such as global climate change and clinical and food analysis – on science, citizens and society. The lectures were grouped into three modules: metrology for quality of life; fundamentals of metrology; and physical metrology and fundamental constants, and topics covered included food supply and safety; biomarkers; monitoring climate and air quality; new IS units; measurement uncertainty; fundamental constants; electrical metrology; optical frequency standards; and photometry and light metrology. The book provides an overview of the topics and changes relevant to metrology today, and will be of interest to both academics and all those whose work involves any of the various aspects of this field.

Proceedings of the NATO Advanced Study Institute, Erice, Italy, May 2-12, 1987

The exchange between physics and metrology is always fascinating and exciting. Many are the open problems in physics that call for extremely precise standards, many are the advances in metrology made possible by a deep and assiduous study of the underlying physics. One has just to think of the enormous sophistication required in the measurements of some absolute quantities such as the Avogadro, the gas, or the gravitational constants. It is also worth noticing that not only the units of a metrological system are interrelated through the fundamental constants, but also the latter find their full significance when they are determined through the most exacting metrological experiments. Over the past decade many improvements took place and these are discussed in this book; from one side the old caesium SI second definition has found a new realisation, with the “fountain” approach, replacing the classical thermal atomic beam. The use of “cold” atom techniques, in which bunches of inert atoms are collected, slowed down, and cooled, has opened a number of new and unexpected avenues for metrology and fundamental constants; one of these possibilities being the atom interferometry. Another important “quantum jump” was the demonstration of the possibility of performing a direct frequency division in the visible, using ultra short femtosecond pulses. In addition, the possibility of “counting” electrons or photons gave a fundamental support to the development of single-electron capacitance standards and to new scenarios in the absolute calibration of photo-detectors.

The spectroscopy of trapped ions or laser-cooled atoms offers the prospect of visible frequency standards to match or even exceed the accuracy of the caesium standard. The development of satellite methods for time comparisons has improved by more than an order of magnitude the accuracy with which national laboratories can routinely compare their clocks. Mechanical metrology has not been left behind. Driven by the need to improve manufacturing technology, major advances have taken place in computer control machining and mechanical measuring systems. These, and many other fascinating developments in the field of metrology are presented in this book.