BY SLOSHING around 13 tonnes of mercury, scientists have made the most accurate measurement yet of Newton’s gravitational constant G. The result adds weight to a controversial theory that the strength of gravity is subtly affected by the Earth’s magnetic field.
The size of G determines the strength of the gravitational pull that bodies exert on each other. But physicists have only a rough idea of its value. The two most accurate measurements of G so far, taken by teams at the University of Washington in Seattle and at the International Bureau of Weights and Measures near Paris, have experimental…
