Stephan Schlamminger and his colleague, Vincent Lee, examine the torsion balance they used to measure the gravitational constant R. Eskalis/NIST For centuries, physicists have been trying to measure the strength of gravity, a number called “big G”. The measurements have never lined up with one another, hinting that either we don’t fully understand our experiments or perhaps we don’t fully understand gravity . The latest test doesn’t confirm either of these scenarios – but the extraordinary precision and care taken in the newest big G experiment may finally bring researchers closer to a consensus. Gravity is much weaker than the other fundamental forces, which makes it extraordinarily hard to measure it precisely. “As kids, we were all mesmerised when we played with magnets by the way they attract each other.…