1
$\begingroup$

As a theorist, I’d guess that in Newtonian gravity we can check for proportionality to mass, and inverse square proportionality to distance, by measuring the ratios of gravitational forces.

Is there similar, fundamental constant independent, test for general relativity?

Improve this question
$\endgroup$
2

1 Answer 1

Reset to default
4
$\begingroup$

When testing a theory you cannot assume the theory. Instead you use a “test theory” that includes the theory of interest as a special case.

The test theory has one or more parameters that can vary, and we make an experiment that is sensitive to the value of that parameter. Then when we run the experiment we can compare the value of the experiment to the value that corresponds to our theory of interest.

For gravity (in the weak field limit like what we see in the solar system) the test theory we use is the parameterized post Newtonian formalism. Different experiments will test different parameters. So far, all of these tests have included general relativity in their experimental limits. See:

https://en.wikipedia.org/wiki/Alternatives_to_general_relativity#Parametric_post-Newtonian_parameters_for_a_range_of_theories

and

https://en.wikipedia.org/wiki/Parameterized_post-Newtonian_formalism#Accuracy_from_experimental_tests

Improve this answer
$\endgroup$
1
  • 2
    $\begingroup$ Thanks a lot. Didn’t know anything about this. Will look into it. All the calculations of predictions of GR I’ve ever studied, used G & c values as given. Also, dark matter always seemed like an arbitrary patchwork to save GR. That’s why I wondered this. $\endgroup$
    – Sachin Vaidya
    Commented Mar 18 at 21:30

Not the answer you're looking for? Browse other questions tagged or ask your own question.