NIST Posts New Values For Constants | Chemical & Engineering News
Volume 89 Issue 30 | p. 28 | Concentrates
Issue Date: July 25, 2011

NIST Posts New Values For Constants

Department: Government & Policy
Keywords: constants, measurement

The National Institute of Standards & Technology is posting the latest internationally recommended values for the fundamental constants of nature. The values are updated every four years by the Committee on Data for Science & Technology Task Group on Fundamental Constants, an international group that includes members from NIST. Among the highlights is the fact that the uncertainty value of the fine structure constant α, which dictates the strength of the electromagnetic force, has been slashed in half to 0.3 ppb. Also revised is the Planck constant, which now has a value of 6.62606957 ×10-34 joule seconds, which takes into account a measurement of the number of atoms in a highly enriched silicon sphere. Other adjustments were made in values for the radius of the proton and in the Rydberg and molar gas constants.

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