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Tag Archives: gravitational constant

In Physics Today, July 2014, Clive Speake and Terry Quinn describe how measurements of G, Newton’s constant of gravitation, have not improved in accuracy as much as might have been expected since Cavendish used the idea to ‘weigh the Earth’ over 200 years ago.

Link: the Physics Today article.


Physicists at the International Bureau of Weights and Measures (BIPM) in Sèvres, France, used a torsion balance to measure Newton’s constant of gravitation, G. Their new combined result, using two independent methods is

G = 6.67545(18) × 10−11 mkg−1 s−2

with an uncertainty of 27 parts per million. This is 241 parts per million above the 2010 value recommended by the international Committee on Data for Science and Technology (CODATA), quoted in Appendix 2A. Their paper will be published in Physical Review Letters.


Credit: BIPM


(See also ‘A Closer Look 5.3’ and ‘Figure It Out 5.2,’ both on p. 110.)