Chapters authored
Measuring ‘Big G’, the Newtonian Constant, with a Frequency Metrology Approach
A new approach is described and discussed to the determination of the Newtonian gravitational constant G, which is based on the very powerful measurement of the frequency difference between two similar oscillators. The rate of change of time delay between the two is equal to their relative frequency difference, and small variations of either one can then be detected via delay monitoring with resolution limited only by time resolution and frequency stability of the two oscillators. The latter should be highly sensitive to gravitational field, to measure G, which triggers the choice of simple pendulums as field detectors. Since the relative effect on frequency readily obtainable in the lab by well-controlled variations of the gravitational field is on the order of 10−7, stabilities on the order of 10−12 are needed of the relative frequency difference if measurement of the fifth decimal digit of G is the target of the experiment. It is argued that such high stability is possible with a pendulum properly designed for being locally isochronous and showing an adequately high Q factor. The latter is projected to reach possibly 107 or more with the discussed design.
Part of the book: Metrology