Physical Constants

Physical Constants

(also fundamental constants), numerical factors that appear in the equations describing physical laws and, in many cases, are scale characteristics of physical processes and microparticles. Physical constants include the speed of light, Planck’s constant, the electron charge, the fine structure constant, Avogadro’s number, and the Rydberg constant.

Physical constants encompass both independent constants and combinations of independent constants, such as the fine structure constant α = e2/ℏc, where e is the electron charge, ℏ is Planck’s constant, and c is the speed of light. The numerical values of physical constants or combinations of such constants are determined on the basis of experimental measurements and are expressed in the units of some established system of units. The determination of the most accurate and reliable values for an entire set of physical constants from data obtained by measurements is called the adjustment of the constants. Adjustment includes the analysis of errors of measurement, the determination of the reliability of the measurements, and the calculation of the adjusted values of the constants by the method of least squares.

The physical constants are more precisely defined with the continuing development of physical experimentation, since new experimental and theoretical possibilities become available for the determination of the constants. For example, the discovery of the Josephson effect made it possible to measure the ratio e/h with a high degree of accuracy and to define many physical constants with substantially more precision. The recommended adjusted values of physical constants as of 1976 are presented in Table 1.

The values of physical constants must be defined more precisely in order to verify physical theories, that is, to compare theoretical predictions with experimental data.

Many measurements in present-day physics and engineering also require knowledge of exact values of physical constants. For example, the exact value of the speed of light must be used in radar measurements.

In metrology, exact values of physical constants are required for the development of reproducible standards for the units in which physical quantities are expressed.

REFERENCES

Taylor, B., W. Parker, and D. Langenberg. Fundamental’nye konstanty i kvantovaia elektrodinamika. Moscow, 1972. (Translated from English.)
“Rekomenduemye soglasovannye znacheniia fundamental’nykh fizicheskikh postoiannykh—1973.” Uspekhi fizicheskikh nauk, 1975, vol. 115, issue 4.
Tabl. standartnykh spravochnykh dannykh: Fundamental’nye fizicheskie konstanty. Moscow, 1976.

L. G. ASLAMAZOV

References in periodicals archive ?
Earlier research had shown that if, for some reason, a few of nature's critical physical constants ever grew too large, matter would subsequently become unstable.
As the definition of basic units, the numerical values ??of seven fundamental physical constants are fixed, among them Planck's constant, elementary charge, Avogadro constant, Boltzmann constant.
[12.] Sirag, Saul-Paul Physical constants as cosmological constraints, International Journal of Theoretical Physics, 1983, v.
Appendices clear up nomenclature, give fundamental physical constants, and give gas-phase ion thermochemical data of molecules and radicals.
This atom is important not only as a model system that tests the limits of atomic theory and experiment, but it also provides information on fundamental physical constants, such as the Rydberg constant.
Determining the values of fundamental physical constants has long served as a test of both physical theory and measurement technology.
From this relation it is clear that, in the presently believed atomic and nuclear "physical constants", there exists one cosmological variable!
Four appendices contain physical constants, units conversion, standards, and acronyms.
Much of his research was directed toward the determination of fundamental physical constants and masses of elementary particles, and toward testing basic theories.
Metrologists have long dreamed of defining the kilogram in terms of the universally agreed upon and unchanging values of fundamental physical constants rather than by an ill-defined lump of grungy matter.
In November 2018, at the General Conference on Weights and Measures in Paris, it is planned to adopt a new definition of a unit of mass through fundamental physical constants and to approve an overdetermined SI system.
Pattern of this field has concentrations (peaks) and rarefractions of integers, which determine special numbers such as e, n, and, probable, the fundamental physical constants (the fine structure constant, the gravitational constant, and the others).

Site: Follow: Share:
Open / Close