The article discusses NIST’s involvement in improving the accuracy of fundamental physical constants, such as the fine-structure constant, electron mass, and Newtonian constant of gravitation G. These constants are crucial for scientific research and have been measured with high precision. NIST collaborates with other scientists worldwide to continually refine these measurements.
The research is conducted under the Task Group on Fundamental Constants, a part of CODATA. The group periodically publishes updated evaluations of these constants, which serve as a consistent reference for the scientific community. The evaluations also help identify inconsistencies in the data and suggest areas for future research.
Some of the constants, like the Planck constant, speed of light, and elementary charge, are exactly defined in the International System of Units (SI). Others, such as the Newtonian constant of gravitation and the fine-structure constant, are known with fewer significant digits. The determination of one constant often relates to the measurement of another, providing redundant information that can be used to validate data.
The article also mentions the role of the equation E H = α 2 m e c 2 in analyzing the relationship between the Rydberg energy, fine-structure constant, and electron mass. The Rydberg energy is most accurately found from hydrogen and deuterium spectroscopy, while the fine-structure constant can be determined through measurements of the electron’s g-factor and the mass of a cesium atom.
Source: https://www.nist.gov/programs-projects/fundamental-constants-nature
Keywords: g-factor, Rydberg constant, fine-structure constant, electron mass, Newtonian constant of gravitation
