— Pericles of Athens. 430BCE
— Maz Jobrani (via seaofgreen)
The gravitational constant G, often called Big G, is an important facet of our universe, much like the speed of light. G appears in the equations that govern the motion of planets and the expansion of the cosmos, and researchers have been trying to accurately pin down its value for more than 200 years. The first experiment to measure Big G was conducted in 1798 by British scientist Henry Cavendish. He set up a clever device in which a dumbbell-like object with two lead balls on either end was suspended by a wire. Another dumbbell was placed so that its balls were near the two spheres. The gravitational attraction between the two sets of balls caused the dumbbell on the wire to twist. A mirror on the wire reflected some candlelight, creating a beam of light that allowed Cavendish to carefully monitor exactly how much the wire rotated. His experiment produced a value for G of;
6.74 × 10−11 m3⁄kg s2
Since then there have been dozens of experiments to measure G using lasers and electronics and producing a modern estimate of;
6.67384 × 10−11 m3⁄kg s2
not far from the 200-plus-year-old experiment’s results.
source: Wired Science