Recommended Values of the Fundamental Physical Constants: A Status Report

Abstract

We summarize the principal advances made in the fundamental physical constants field since the completion of the 1986 CODATA least-squares adjustment of the constants and discuss their implications for both the 1986 set of recommended values and the next least-squares adjustment. In general, the new results lead to values of the constants with uncertainties 5 to 7 times smaller than the uncertainties assigned the 1986 values. However, the changes in the values themselves are less than twice the 1986 assigned one-standard-deviation uncertainties and thus are not highly significant. Although much new data has become available since 1986, three new results dominate the analysis: a value of the Planck constant obtained from a realization of the watt; a value of the fine-structure constant obtained from the magnetic moment anomaly of the electron; and a value of the molar gas constant obtained from the speed of sound in argon. Because of their dominant role in determining the values and uncertainties of many of the constants, it is highly desirable that additional results of comparable uncertainty that corroborate these three data items be obtained before the next adjustment is carried out. Until then, the 1986 CODATA set of recommended values will remain the set of choice.

Keywords: CODATA; Josephson effect; Task Group on Fundamental Constants; conversion factors; electrical units; fundamental physical constants; least-squares adjustment; quantum Hall effect; recommended values of the constants.

Figure 1

Graphical comparison of the values of the Rydberg constant for infinite mass R_∞ given in table 1.

Figure 2

Graphical comparison of the stochastic input data through a comparison of values of K_Ω = (R_K/R_K−90)= µ₀cα⁻¹/2R_K−90 given in table 3. With the exception of the 1986 CODATA recommended value, these values are taken directly from or are derived from the stochastic data of table 2.

Figure 3

Graphical comparison of the stochastic input data through a comparison of values of K_V=(K_J−90/K_J)=K_J−90/ (2e/h) given in table 4. With the exception of the 1986 CODATA recommended value, these values are taken directly from or are derived from the stochastic data of table 2. (Because its severe disagreement with the other values of K_v is obvious, value No. 9 of table 4, that derived from the ASMW value of $\gamma {\prime }_{\mathrm{p}}$ (data item 7.2 of table 2), has been omitted from the figure to allow the use of a higher resolution scale.)

Figure 4

Graphical display of the results of Adjustment No. 1 given in table 7. The closed circles with error bars indicate the 1986 CODATA recommended values and their one-standard-deviation uncertainties; the open circles with error bars indicate the values and their one-standard-deviation uncertainties derived from the data of table 2 through Adjustment No. 1, relative to the 1986 values.