The Fundamental Constants Data Center is focused on physics relevant to the determination of values of the fundamental constants of physics and chemistry. Activities include gathering and analyzing information for, and carrying out periodic least-squares evaluations of the constants. When necessary, new theoretical calculations are carried out to provide additional information for the adjustments. The Data Center is also involved in the development of the International System of Units, which is the basis for expressing the values of the constants. Support for research relevant to the fundamental constants and tests of basic laws of physics is provided through the Precision Measurements Grants Program.

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**Group Members**

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**Precision Measurement Grants Program**—Since 1970, the National Institute of Standards and Technology (NIST) has awarded Precision Measurement Grants to faculty members of U.S. universities or colleges for significant research in the …

**Newtonian constant of gravitation international consortium**—The Newtonian constant of gravitation G is one of the most fundamental constants of classical physics. Recent measurements of G are in disagreement, with discrepancies that are roughly ten times …

**CODATA values of the fundamental constants**—Every four years, the Committee on Data for Science and Technology (CODATA) issues recommended values of the fundamental physical constants. The values are determined by a least-squares adjustment, …

**International System of Units (SI)**—The International System of Units (SI) provides definitions of units of measurement that are widely accepted in science and technology and which set measurement standards agreed to through the …

**Quantum Physics Theory**—Theoretical work relevant to the determination of values of the fundamental constants, tests of bound-state quantum electrodynamics (QED), and methods of numerical analysis are included among the …