I know that there has been a large amount of controversy surrounding the exact value of the gravitational constant $G$, but I know that there is not a substantial difference in the measured value. So I was wondering what experimental bounds we have on it so far?

  • $\begingroup$ we don't have even good experimental bounds on torsion $\endgroup$
    – lurscher
    Mar 6, 2018 at 17:46
  • $\begingroup$ What is torsion? In gravitational theory. $\endgroup$ Mar 6, 2018 at 18:45

2 Answers 2


This page shows the range of some measurements from 1982 to 2014. Basically, it looks like arguments could be made for any value between -460 to +250 parts per million below or above the commonly accepted value of 6.67408 x 10^-11 m^3 kg^-1 s^-2.



According to NISTconstants, as of 2017, $$G = 6.674 08(31) \times 10^{-11} \space {\rm m}^3 {\rm kg}^{-1} {\rm s}^{-2} $$ which means the range is 6.67377 to 6.67439

It's not the easiest measurement to make, large forces from electrical, magnetic, and other sources have to be considered.

  • 2
    $\begingroup$ Isn't the number in brackets the standard deviation in the results? That is, G could conceivably be > 6.67439, but the probability of that is < 32%. $\endgroup$
    – Allure
    Mar 7, 2018 at 3:45
  • $\begingroup$ @Allure That's possible, but it could also be a hard limit based on systematics (nonrandom variables). I tracked a paper that gives experimental results, Phys Rev Lett 23(10), from 1969, but I only have the reference, haven't visited the library. $\endgroup$
    – Whit3rd
    Mar 7, 2018 at 4:12
  • $\begingroup$ @allure that's not the meaning of a confidence interval. In 68% of the hypothetical repeat experiments, an interval produced in that manner would include the true $G$, were the model true $\endgroup$
    – innisfree
    Mar 20, 2018 at 12:43

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