CODATA recommended values of the fundamental physical constants: 2022

The experimental data of Table I upon which Dr. COHE~ and I have based our latest set of values for the universal physical constants f~ll into two groups. In the group I shall discuss first, seven precisely measured experimental data which are so interrelated that they overdetermine four primary unknowns. This situation requires us to arrive at the output results by a least squares adjustment. The auxiliary constants, which constitute the second group, on the other hand, are quantities so precisely known relative to the accuracy of the measurements of the first group, and are involved with the latter in the least squares adjustment in such a fashion, that nothing is gained by treating them as adjustable unknowns. Their measured values are therefore not subject to adjustment and are treated as though they were exactly known constants. The four primary unknowns which we have selected for the least-squares adjustment are the Sommerfeld fine structure constant, ~; the electronic charge, e; the Avogadro number, 2V, and the conversion constant, A ~-- 2g/2~, relating the two scales of wavelength, in angstroms on the one hand and in kilo X-units (SIEG~AHS) on the other. Seven different functions of these four unknowns have been measured by experimental methods which we feel are sufficiently precise and reliable to qualify them as input data in a least squares adjustment. These seven experimentally determined numerical values arc not only functions of the unknowns, ~, e, N, and A, but also of the above mentioned experimentally determined auxiliary constants, of which last I shall mention five different kinds. One of these auxiliary constants I find it expedient to recall to your attention at the very beginning to avoid any possibility of confusion. This is the conversion factor, r, between the > and > scales of atomic weight.

We report the 2018 self-consistent values of constants and conversion factors of physics and chemistry recommended by the Committee on Data of the International Science Council. The recommended values can also be found at physics.nist.gov/constants. The values are based on a least-squares adjustment that takes into account all theoretical and experimental data available through 31 December 2018. A discussion of the major improvements as well as inconsistencies within the data is given. The former include a decrease in the uncertainty of the dimensionless fine-structure constant and a nearly two orders of magnitude improvement of particle masses expressed in units of kg due to the transition to the revised International System of Units (SI) with an exact value for the Planck constant. Further, because the elementary charge, Boltzmann constant, and Avogadro constant also have exact values in the revised SI, many other constants are either exact or have significantly reduced uncertainties. Inconsistencies remain for the gravitational constant and the muon magnetic-moment anomaly. The proton charge radius puzzle has been partially resolved by improved measurements of hydrogen energy levels.

We report the 2018 self-consistent values of constants and conversion factors of physics and chemistry recommended by the Committee on Data of the International Science Council (CODATA). The recommended values can also be found at physics.nist.gov/constants. The values are based on a least-squares adjustment that takes into account all theoretical and experimental data available through 31 December 2018. A discussion of the major improvements as well as inconsistencies within the data is given. The former include a decrease in the uncertainty of the dimensionless fine-structure constant and a nearly two orders of magnitude improvement of particle masses expressed in units of kg due to the transition to the revised International System of Units (SI) with an exact value for the Planck constant. Further, because the elementary charge, Boltzmann constant, and Avogadro constant also have exact values in the revised SI, many other constants are either exact or have significantly reduced uncertainties. Inconsistencies remain for the gravitational constant and the muon magnetic-moment anomaly. The proton charge radius puzzle has been partially resolved by improved measurements of hydrogen energy levels.

Committee on Data of the International Science Council recommends the latest values of constants and conversion factors of physics and chemistry based on a least-squares adjustment

It is now recognized that the International System of Units (SI units) will be redefined in terms of fundamental constants, even if the date when this will occur is still under debate. Actually, the best estimate of fundamental constant values is given by a least-squares adjustment, carried out under the auspices of the Committee on Data for Science and Technology (CODATA) Task Group on Fundamental Constants. This adjustment provides a significant measure of the correctness and overall consistency of the basic theories and experimental methods of physics using the values of the constants obtained from widely differing experiments. The physical theories that underlie this adjustment are assumed to be valid, such as quantum electrodynamics (QED). Testing QED, one of the most precise theories is the aim of many accurate experiments. The calculations and the corresponding experiments can be carried out either on a boundless system, such as the electron magnetic moment anomaly, or on a bound system, such as atomic hydrogen. The value of fundamental constants can be deduced from the comparison of theory and experiment. For example, using QED calculations, the value of the fine structure constant given by the CODATA is mainly inferred from the measurement of the electron magnetic moment anomaly carried out by Gabrielse's group. (Hanneke et al. 2008 Phys. Rev. Lett. 100, 120801) The value of the Rydberg constant is known from two-photon spectroscopy of hydrogen combined with accurate theoretical quantities. The Rydberg constant, determined by the comparison of theory and experiment using atomic hydrogen, is known with a relative uncertainty of 6.6×10(-12). It is one of the most accurate fundamental constants to date. A careful analysis shows that knowledge of the electrical size of the proton is nowadays a limitation in this comparison. The aim of muonic hydrogen spectroscopy was to obtain an accurate value of the proton charge radius. However, the value deduced from this experiment contradicts other less accurate determinations. This problem is known as the proton radius puzzle. This new determination of the proton radius may affect the value of the Rydberg constant . This constant is related to many fundamental constants; in particular, links the two possible ways proposed for the redefinition of the kilogram, the Avogadro constant N(A) and the Planck constant h. However, the current relative uncertainty on the experimental determinations of N(A) or h is three orders of magnitude larger than the 'possible' shift of the Rydberg constant, which may be shown by the new value of the size of the proton radius determined from muonic hydrogen. The proton radius puzzle will not interfere in the redefinition of the kilogram. After a short introduction to the properties of the proton, we will describe the muonic hydrogen experiment. There is intense theoretical activity as a result of our observation. A brief summary of possible theoretical explanations at the date of writing of the paper will be given. The contribution of the proton radius puzzle to the redefinition of SI-based units will then be examined.

The 1952 data used by DuMond and Cohen in an evaluation of the atomic constants are analyzed for the presence of systematic errors by a variance analysis performed by an electronic digital computer. For simplicity the velocity of light is treated as a fixed constant of known value and there remain then eleven linear equations in four unknowns subject to least-squares adjustment. Least-squares adjustments of 219 over-determined subsets of these equations have been made and ${\ensuremath{\chi}}^{2}$ has been evaluated for each such subset. An analysis of these data indicates that small systematic errors are most likely to exist in the following input data: (1) The determination of the Faraday by the silver voltameter. (2) The determination of the cyclotron resonance frequency of the proton by the inverse cyclotron method of Bloch and Jeffreys. (3) Certain of the higher voltage determinations of $\frac{h}{e}$ by the continuous x-ray quantum limit. In descending order of magnitude of discrepancy from the remaining data on the constants are the determinations of (a) Felt, Harris, and DuMond made at 24 500 volts, (b) Bearden and Schwarz at 19 600 volts, (c) Bearden and Schwarz and also Bearden, Johnson, and Watts in the region between about 10 kv and about 6 kv. An analysis of the various observations taken by these observers at different voltages reveals a possible systematic trend when discrepancy is plotted against either voltage or window width in volts. Conjectures to account for the effect are discussed.The modifications called for by this analysis yield a new 1955 adjustment in which ${\ensuremath{\chi}}^{2}$ is smaller than it was for the November, 1952 adjustment. The new ${\ensuremath{\chi}}^{2}=3.25$ is satisfactorily close to its expected value, 3. Thanks to the fact that the error measures adopted in the November, 1952 adjustment for the output values were conservatively based on the criterion of external consistency, the changes in the values occasioned as a result of the present analysis are all well within those estimated limits. A welcome effect of this new adjustment is that the adjusted output value of $\frac{{\ensuremath{\lambda}}_{g}}{{\ensuremath{\lambda}}_{s}}$, the conversion factor from Siegbahn's $x$-units to milliangstroms, now lies much closer to the input value. A new table of constants and conversion factors is presented.

A new set of values of the basic fundamental constants has been recommended by the Committee on Data for Science and Technology (CODATA) (http://phvsics.nist.gov/cuu/Constants/). It is based on a least-squares adjustment that incorporates new data that became available before the closing date of 31 December 2006 (known as the 2006 LSA). A number of key advances in experiment and theory have led to significant improvements in our knowledge of the values of the constants. The consequences of the new results and how the values were determined will be discussed.

Status of knowledge of the fundamental constants of physics and chemistry as of January 1959

Gamma-ray energies from 14N(n, γ) 15N and 23Na(n, γ) 24Na reactions: A re-evaluation

This report gives the 2014 self-consistent set of values of the constants and conversion factors of physics and chemistry recommended by the Committee on Data for Science and Technology (CODATA). These values are based on a least-squares adjustment that takes into account all data available up to 31 December 2014. The recommended values may also be found on the World Wide Web at physics.nist.gov/constants.

This paper gives the 2014 self-consistent set of values of the constants and conversion factors of physics and chemistry recommended by the Committee on Data for Science and Technology (CODATA). These values are based on a least-squares adjustment that takes into account all data available up to 31 December 2014. Details of the data selection and methodology of the adjustment are described. The recommended values may also be found at http://physics.nist.gov/constants.

In-plane force constants of the peptide group: Least-squares adjustment starting from ab initio values of N-methylacetamide

While the discussion on data for development gains traction in society especially with the focus on Sustainable Development Goals (SDGs), there is the need for more insight into the long-standing global perspectives on data and information for science. The International Science Council (ISC) established in 1932 as International Council for Scientific Unions (ICSU) aims to strengthen international science for the benefit of society. The key principle is the “Universality of Science”1 which interprets science as a collective effort working for the common good, but a growing number of scientists, policy-makers, and social scientists argue that science is often too isolated from society to fulfil this promise. This brings in the concept of ‘Open Science’ to close the gap between science and society by democratizing scientific knowledge, for the benefit of everyone. The Committee on Data (CODATA), an interdisciplinary body of ISC is the focus of this paper, along with recent perspectives regarding its role and needs of science in the present information-driven society.

Science as a Global Public Good

Views Icon Views Article contents Figures & tables Video Audio Supplementary Data Peer Review Share Icon Share Twitter Facebook Reddit LinkedIn Tools Icon Tools Reprints and Permissions Cite Icon Cite Search Site Citation A. Ya. Faenov, A. I. Magunov, T. A. Pikuz, I. Yu. Skobelev, P. A. Loboda, N. N. Bakshayev, S. V. Gagarin, V. V. Komosko, K. S. Kuznetsov, S. A. Markelenkov, S. A. Petunin, V. V. Popova; Spectr‐W3 Online Database On Atomic Properties Of Atoms And Ions. AIP Conf. Proc. 21 October 2002; 636 (1): 253–262. https://doi.org/10.1063/1.1516342 Download citation file: Ris (Zotero) Reference Manager EasyBib Bookends Mendeley Papers EndNote RefWorks BibTex toolbar search Search Dropdown Menu toolbar search search input Search input auto suggest filter your search All ContentAIP Publishing PortfolioAIP Conference Proceedings Search Advanced Search |Citation Search