The Newtonian gravitational constant G was the first known fundamental constant of physics. Nevertheless, the measurement of its value still seem to be in a rather sad shape. Recently, the CODATA Task Group on Fundamental Constants recommended a preliminary value of G with a relative uncertainty of 0.15 %. This is more than ten times larger as the previous recommendation!
In the first part of this lecture, a brief summary is given of recent experimental efforts to determine G. The second part is a description of our experiment at the University of Zürich.
We use a beam balance to measure the gravitational forces of large field masses (13.5 × 103 kg mercury) on 1 kg test masses. A first result with an uncertainty of 220 × 10?6 has been published recently. Presently we are working to improve the experiment.
Systematic Uncertainty Test Mass Fundamental Constant Beam Balance Torsion Balance
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