Stephan Schlamminger (left) and colleague Vincent Lee with the equipment used to measure big G . Credit: R. Eskalis/NIST The value of the constant that describes the gravitational pull between objects, Big G , continues to baffle scientists. A decade-long replication experiment 1 that involved moving equipment across the Atlantic has resulted in a number that disagrees with previous results, and also differs from the current best estimate of G . The new measurement gives important clues as to where the original experiment, conducted by researchers at the International Bureau of Weights and Measures (BIPM) in Paris and published in 2013 , went wrong. But its failure to match the internationally agreed CODATA value has left physicists no closer to pinning down G ’s true value. Is gravity quantum?…