The Newtonian gravitational parameter G is a constant in both Newton's law of gravitation and Einstein's general theory of relativity. However, over the last fifty years there have been numerous suggestions that G might in fact change with time. The detailed grounds for these suggestions have differed, but most variable‐G theories account for gravitation on a cosmological basis. As such, they usually involve a time‐dependent G: where t is a parameter that can, loosely speaking, be interpreted as the “age” of the Universe. A value of G that depends on time is a drastic departure from the established physics of gravitation (based on Newton's and Einstein's theories). Before looking at G‐variability in detail it is therefore logical to ask first: Why should G vary?
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July 1980
July 01 1980
Does gravity change with time?
Highly regarded theories hold that the gravitational “constant” should decrease with time. To date no observations have refuted this prediction and some offer positive evidence supporting it.
Physics Today 33 (7), 32–37 (1980);