Metrology and fundamental physical constants

Fundamental problems of modern metrology are considered. It is suggested that problems arising in metrology during the construction of a system of measurement units are resolved at two levels: fundamental (theoretical) and practical. The increasing importance of developing and applying standards based directly on fundamental physical constants is noted. __________ Translated from Izmeritel’naya Tekhnika, No. 2, pp. 3–7, February, 2006.     

The fundamental constants and the transition to new definitions of the SI units

Problems in fundamental metrology associated with variations in constants and the planned transition to new definitions of SI units based on fixed values of the fundamental physical constants are examined. It is pointed out that all the necessary conditions for such a transition have not yet been satisfied.     

The Ampere and Electrical Standards

This paper describes some of the major contributions to metrology and physics made by the NIST Electricity Division, which has existed since 1901. It was one of the six original divisions of the National Bureau of Standards. The Electricity Division provides dc and low-frequency calibrations for industrial, scientific, and research organizations, and conducts research on topics related to electrical metrology and fundamental constants. The early work of the Electricity Division staff included the development of precision standards, such as Rosa and Thomas standard resistors and the ac-dc thermal converter. Research contributions helped define the early international system of measurement units and bring about the transition to absolute units based on fundamental principles and physical and dimensional measurements. NIST research has helped to develop and refine electrical standards using the quantum Hall effect and the Josephson effect, which are both based on quantum physics. Four projects covering a number of voltage and impedance measurements are described in detail. Several other areas of current research at NIST are described, including the use of the Internet for international compatibility in metrology, determination of the fine-structure and Planck constants, and construction of the electronic kilogram.     

Quantum Standard for Units of Length,Time, Mass and Fundamental Physical Constants

Contemporary methods are considered for storage and reproduction of the dimensions of basic SI units, i.e., length, time, and mass. The main trends are discussed for improving these methods in order to reduce reproduction errors for the dimensions of units. The importance of using results of theoretical calculations for microprocess characteristics and precise values for a number of fundamental physical constants is noted. __________ Translated from Izmeritel'naya Tekhnika, No. 8, pp. 3–7, August, 2005.     

The Fundamental Physical Constants,the Gravitational Constant,and the See Space Experiment Project

The paper discusses the fundamental physical constants, the classification of them, the number of them, the definition accuracy, and the relationships to fundamental physical theories (interactions). Basic concepts are presented on gravitational relativistic metrology related to precision space-time measurements. The main attention is given to Newton’s gravitational constant G as regards the measurement of the absolute value and the possible variations in time and space as predicted by interaction union theories. Principles are presented for a proposed space experiment to measure G and its variations, whose implementation will enable one to improve on current data from appropriate laboratory experiments on Earth by 2–3 orders of magnitude.__________Translated from Izmeritel’naya Tekhnika, No. 6, pp. 3–10, June, 2005.     

关于计量单位向量子基准发展的趋势

本文从计量学的基本特性出发,讨论了计量单位由实物基准向量子基准发展的必然性,提出了 SI 的几个单位建立量子基准的初步构想,最后还指出了基本物理常数及共组合与计量单位的对应关系以及精测这些常数的重要性。     

Fundamental physical constants in the new international system of units (SI)

The current trend toward redefining all the units in the international system (SI) in terms of fundamental physical constants is discussed. It is noted that fixing the value of an appropriate physical constant is sufficient for defining a unit. A demonstration is provided of defining the entire SI through a set of exact values of appropriately chosen fundamental constants with no distinction between basic and derived units.     

Changes in the International System of Units proposed in recommendation E1 (2007) of the consultative committee on electricity and magnetism

Changes in the definitions of the technical units and units of electromagnetism in the International System of Units which may be adopted if Recommendation E1 (2007) is approved are discussed. It is shown that the verbal statement of the definition of the kilogram may be radically simplified if the division of units into fundamental and derived units is discarded in the new International System of Units. __________ Translated from Izmeritel’naya Tekhnika, No. 8, pp. 69–71, August, 2007.     

The Current SI Seen From the Perspective of the Proposed New SI

A revised International System of Units (SI) proposed by the International Committee for Weights and Measures is under consideration by the General Conference on Weights and Measures for eventual adoption. Widely recognized as a significant advance for both metrology and science, it is defined via statements that explicitly fix the numerical values of a selected set of seven reference constants when the values of these constants are expressed in certain specified units. At first sight this approach to defining a system of units appears to be quite different from that used to define the current SI. However, by showing how the definitions of the seven base units of the current SI also fix the numerical values of a set of seven reference constants (broadly interpreted) when the values of these constants are expressed in their coherent SI units, and how the definition of the current SI can be recast into the same form as that of the revised SI under consideration, we show that the revision is not as radical a departure from the current SI as it might initially seem.     

Harmonizing the terminological subsystem “Standards for units of physical quantities”

Suggestions are considered on harmonizing the terms in the terminological subsystem “Standards for units of physical quantities.” Proposals are made on upgrading intergovernmental terminological documents. Definitions are given of terms proposed for use. Editor's note. Terminology is extremely important for metrology, so this paper is useful. However, it has become customary to use the term “means of measurement,” so it is hardly desirable to introduce a new definition for “means of measurement engineering.” As regards the suggestion on the direct introduction of the international dictionary of basic and general terms in metrology, the Publishing House for Standards in 1998 published this dictionary in Russian with equivalents for the terms in English, French, German, and Spanish (see Izmeritel'naya Tekhnika, No. 12, p. 62, 1998). Translated from Izmeritel'naya Tekhnika, No. 4, pp. 40–42, April, 1999.     

Need to update the metrological paradigm

It is shown to be necessary to increase the precision of the definition of the initial propositions of metrology utilizing the contemporary theory of measurement scales. A field of applied metrology is identified which fundamentally fails to be included by the international system (SI) of units. The functions of measurement standards, measuring transducers, and comparators are defined more precisely. Evidence is given of the strong desirability of updating the State and international normative documents on metrology. Translated from Izmeritel'naya Tekhnika, No. 8, pp. 15–21, August, 1998.     

Proposed Changes to the SI: A Glimpse into the Future

Recent proposals to fundamentally change the international system of units (SI) have generated considerable debate and are now being seriously considered by international committees. These proposals have a common theme—to exactly fix the values of a set of fundamental physical constants and to then base the SI units with respect to these invariant constants. This article will summarize the proposed changes and outline how national standards institutes would typically realize the SI units within the new system. The expected benefits and drawbacks of these changes will be summarized as they pertain to measurement science and fundamental constants. The official positions of different metrological communities as well as possible time schedules and the approval process that must be followed to implement such changes to the SI will be outlined.     

Physical Nature of Measurement Uncertainty in Metrology

It is shown that the problem of measurement uncertainty in metrology is many-sided and must be interpreted not only on the basis of the purely statistical processing of data but also taking account of the definition of a physical quantity as a fundamental triad: observable, state, average value. It is shown that inaccuracy and uncertainty are two realities associated with a lack of information concerning the system of knowledge.     

Some methods for redefining the unit of mass standard fundamental problems in metrology

Contemporary methods are presented for redefining the unit of mass standard, i.e., the kilogram prototype. The main tendencies in improving these methods in order to reduce the uncertainty of reproducing the unit of mass are discussed. It is noted that the use of precise values of a number of fundamental physical constants, primarily the Avogadro number, is important. __________ Translated from Izmeritel’naya Tekhnika, No. 4, pp. 3–7, April, 2006.     

Base units of the SI, fundamental constants and modern quantum physics

Over the past 40 years, a number of discoveries in quantum physics have completely transformed our vision of fundamental metrology. This revolution starts with the frequency stabilization of lasers using saturation spectroscopy and the redefinition of the metre by fixing the velocity of light c. Today, the trend is to redefine all SI base units from fundamental constants and we discuss strategies to achieve this goal. We first consider a kinematical frame, in which fundamental constants with a dimension, such as the speed of light c, the Planck constant h, the Boltzmann constant k(B) or the electron mass m(e) can be used to connect and redefine base units. The various interaction forces of nature are then introduced in a dynamical frame, where they are completely characterized by dimensionless coupling constants such as the fine structure constant alpha or its gravitational analogue alpha(G). This point is discussed by rewriting the Maxwell and Dirac equations with new force fields and these coupling constants. We describe and stress the importance of various quantum effects leading to the advent of this new quantum metrology. In the second part of the paper, we present the status of the seven base units and the prospects of their possible redefinitions from fundamental constants in an experimental perspective. The two parts can be read independently and they point to these same conclusions concerning the redefinitions of base units. The concept of rest mass is directly related to the Compton frequency of a body, which is precisely what is measured by the watt balance. The conversion factor between mass and frequency is the Planck constant, which could therefore be fixed in a realistic and consistent new definition of the kilogram based on its Compton frequency. We discuss also how the Boltzmann constant could be better determined and fixed to replace the present definition of the kelvin.     

计量与数理的关系及分形维应用研究

在重点综述数学中抽象空间、物理学中能观测量和计量单位或单位制的相互关系基础上,探索并整理出各学科共同依赖的某些基本准则或公理,以便建立一个较为完整的广义科学框架或系统描绘现存的学科基石.在此基础上,为提供现有科学新的分类和启迪新的科学研究方法和探索自然奥秘提供新的综合手段达到抛砖引玉的目的.除此以外,作为近代数学对较复杂事物计量分析的应用例,提出微观粒子的太极模型分形维.     

Optimum choice of fundamental physical constants with fixed values for redefinition of SI units

The advantages and disadvantages of the procedure of fixing the values of fundamental physical constants (FPC) for redefining the basic SI units are examined. The case in which a fixed value of the Avogadro constant is used simultaneously for new definitions of the unit of mass and the unit of the amount of matter is discussed in detail. A criterion is proposed for choosing the optimum set of FPC with fixed values for redefining basic SI units. A set of FPC compatible with this criterion is considered.     

电磁计量学研究进展评述

2019年5月20日,国际单位制(SI)实现了7个基本单位均以基本物理常数为基准,计量体系迎来“计量单位量子化”和“量值传递扁平化”重大变革。电磁计量在计量学领域中占据极为重要的地位,开展电磁计量研究对保持我国量值传递先进性、促进计量学新发展具有重要意义。介绍了电磁计量的基本特性,综述了其在量子标准及芯片、能量天平、交流电量计量、交流阻抗及比率计量、高压计量、磁参量计量等方面的国内外发展现状,对电磁计量科学技术的发展趋势进行了展望。     

Possible definition of the unit of mass and fixed values of the fundamental physical constants

Ways of increasing the accuracy of the values of the Planck and Avogadro constants in experiments with Watt balances and crystalline silicon spheres are examined. These are needed for the new definitions of the kilogram and mole. The advantages and disadvantages of fixing the values of a number of fundamental physical constants when introducing definitions of the SI units are discussed, in particular a new definition of the unit of mass based on a fixed value of the Avogadro constant.     

Matching Fundamental Constants and Reproducing Units for Physical Quantities

Theoretical and methodological aspects are discussed in using the fundamental physical constants (FPC) to reproduce units for physical quantities. Effects are considered from matching up the FPC on the accuracy in reproducing the units for electrical quantities as well as the role of the FPC in unit system construction.