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?
$\begingroup$
$\endgroup$
2
asked Mar 6, 2018 at 17:27
-
$\begingroup$ we don't have even good experimental bounds on torsion $\endgroup$– lurscherMar 6, 2018 at 17:46
-
$\begingroup$ What is torsion? In gravitational theory. $\endgroup$– The victorious trutherMar 6, 2018 at 18:45
Add a comment
|
2 Answers
$\begingroup$
$\endgroup$
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.
http://iupap.org/working-groups/wg13-newtonian-constant-of-gravitation/
$\begingroup$
$\endgroup$
3
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%. $\endgroup$– AllureMar 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. $\endgroup$– Whit3rdMar 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 $\endgroup$ Mar 20, 2018 at 12:43