Fixler and Kasevich's measurement of this quantity relied on measuring the differentialacceleration of two cesium samples. This quantity appears multiplied by the density and eight-thirdspi in one term of the Friedmann equations. This constant appears over the speed of light to the fourthpower in the coefficient of the stress-energy tensor in Einstein's field equations. A 
Fixler and Kasevich's measurement of this quantity relied on measuring the differentialacceleration of two cesium samples. This quantity appears multiplied by the density and eight-thirdspi in one term of the Friedmann equations. This constant appears over the speed of light to the fourthpower in the coefficient of the stress-energy tensor in Einstein's field equations. A device invented byJohn Michell was used in the first measurement of this quantity; that experiment used a (*) torsionbalance and was done by Henry Cavendish, who originally was trying to measure the density of the earth.For 10 points, name this constant equal to 6.67 times 10 to the negative 11th in SI units, which is multipliedby two masses over r squared in a law named for Newton.
Fixler and Kasevich's measurement of this quantity relied on measuring the differentialacceleration of two cesium samples.
big G [or universal gravitational constant or Newton's constant before mention]