Skip to content a 225-year effort… and counting Such experiments bring “order to the universe, whether or not the number agrees with the expected value.” NIST scientists Stephan Schlamminger (left) and Vincent Lee examine the torsion balance they used to measure the gravitational constant ("Big G"), a decade-long undertaking. Credit: R. Eskalis/NIST The gravitational constant, affectionally known as “Big G,” is one of the most fundamental constants of our universe. Its value describes the strength of the gravitational force acting on two masses separated by a given distance—or if you want to be relativistic about it, the amount a given mass curves space-time. Physicists have a solid ballpark figure for the value of Big G, but they’ve been trying to measure it ever more precisely for more than two centuries, each effort yielding slightly different values. And we do mean slight: The values vary by roughly one part in 10,000. Still, other fundamental constants are known much more precisely.…