But you're just demonstrating the annoying aspect of MOND: it's not one theory, so it fails that first requirement of being science, that it be falsifiable.
We see this all the time when MOND is tested. It ends up failing, but then the proponents say "oh, well, it's not that MOND we're talking about". It's like some sort of pseudoscientific cockroach that keeps escaping after you crush it with a shoe.
Any specific variant of MOND, with definite formulae for the gravitational quantities, is falsifiable. (Though it may not be very easy to verify or falsify it, because besides the hypothetical "dark matter" there also exists true dark matter, i.e. interstellar gas and dust clouds.)
Any theory based on dark matter is not falsifiable, regardless what model is used for gravitation, because for now there is no constraint on the distribution of the dark matter.
The only way for the theory of dark matter to become a scientific theory is to discover an alternative way to determine where the dark matter is located, besides placing it wherever necessary to remove the discrepancies between the observations of the movements of the celestial bodies and the predictions of the current model of gravitation.
Isn't this essentially the same problem with Dark Matter though? They keep looking for it, not finding it and proclaiming "well, it must be somewhere else!".
I always got the impression that when Dark Matter was initially labelled as such, it was just a name for the discrepancy between theoretical models and observations; and that the name itself seems to have driven this idea that it's the observations that are wrong and not the models.
Personally, when discussing Dark Matter vs. MOND, I think neither should be treated as a concrete "theory", but simply a different perspective on where the problem lies. "Dark Matter" is the idea that our observations are incomplete, and MOND is the idea that our theoretical models are wrong.
Hopefully this conundrum is resolved within my lifetime, because I'd love to know what the answer is. It would be absolutely wild if they're both right i.e. that our observations are incomplete and our models are wrong.
> that our observations are incomplete and our models are wrong.
I'd say that's a given regardless of the DM mystery.
It's consensus that QM and GR are incompatible and that we need a new theory out of which both of these come out as a special case. String theory was considered a hopeful contender for that for a while.
And that we haven't observed everything to a satisfying degree yet should be obvious.
> Isn't this essentially the same problem with Dark Matter though? They keep looking for it, not finding it and proclaiming "well, it must be somewhere else!".
No (unless you mean "where" in parameter space), we have a pretty good idea where it is thanks to gravitational lensing surveys. We don't what it is.
We see this all the time when MOND is tested. It ends up failing, but then the proponents say "oh, well, it's not that MOND we're talking about". It's like some sort of pseudoscientific cockroach that keeps escaping after you crush it with a shoe.