Shapiro and collaborators showed that radar-echo time delay measurements between planets constrain it to change by no more than a part in 10 billion p
Shapiro and collaborators showed that radar-echo time delay measurements between planets constrain it to change by no more than a part in 10 billion per year. Dirac had suggested, in some numerology known as the "large numbers hypothesis," that it decreases over time. In string theory, the effective value is inversely proportional to the volume of the compactification manifold. In a system of units with h-bar and c set to 1, it is simply one over the Planck mass squared. Its value is 6.67 times 10 to the minus 8 cubic centimeters per gram second-squared. It was first measured, using a torsion balance, by Henry Cavendish. For 10 points, what is this constant, which multiplies the masses of two objects divided by the square of their separation to give a universal force between them?
Shapiro and collaborators showed that radar-echo time delay measurements between planets constrain it to change by no more than a part in 10 billion per year.
Newton's constant [or "G Newton" or the universal gravitational constant or big G]