The issue is that MOND is being marketed as being able to fix things that we already know it isnt capable of fixing. This is the astronomy equivalent of an experimental drug tauted to cure cancer rather than a specific form of it (if it works at all.) The biggest issue I have with MOND is that the mechanism for modified gravity isn’t derived like relativity was (i.e relativity has a mechanism that naturally leads to its equations) but designed post facto to fit observations. i.e a0 was not derived from scratch, it was curve fit. A curve that does not appear to explain ultra diffuse galaxies which are apparently essentially free of dark matter. If MOND had some theoretical basis behind it beyond “stars in galaxies go brrr” and could explain the apparent lack of deviation from newtonian gravity of ultra diffuse galaxies, it might have deserved more attention.
I mentioned galactic rotation curves because thats more or less where it began. If MOND fails to fit the data at those scales, it will necessarily fail within our own solar system at the outer edges where a0 would potentially be relevant.
There are many variants of MOND. RelMOND, for example, includes features that resemble dark matter more closely.
I’m not saying “it’s gotta be MOND”, of course. I’m just reacting to what I perceive as an unnecessarily hostile reaction to it. We have yet to actually figure out dark matter either, after all, and there are many variants of dark matter that have been proposed. So the “it’s designed post facto to fit observations” is a complaint that can be directed against it right now too. I see nothing wrong with exploring all the options, especially when it’s by people who have chosen to spend their efforts doing that for themselves.
None of them are based on anything though. Theyre curve fitting models which is why I am hostile to them. Show me a mechanism that derives what a0 is from scratch.
Basing a model on how well it fits a curve rather than on a mechanism that naturally derives the curve from scratch is essentially worthless.
Without a mechanism that explains why there needs to be a MOND dominated regime in the first place, its just too susceptible to being pathological science.
The issue is that MOND is being marketed as being able to fix things that we already know it isnt capable of fixing. This is the astronomy equivalent of an experimental drug tauted to cure cancer rather than a specific form of it (if it works at all.) The biggest issue I have with MOND is that the mechanism for modified gravity isn’t derived like relativity was (i.e relativity has a mechanism that naturally leads to its equations) but designed post facto to fit observations. i.e a0 was not derived from scratch, it was curve fit. A curve that does not appear to explain ultra diffuse galaxies which are apparently essentially free of dark matter. If MOND had some theoretical basis behind it beyond “stars in galaxies go brrr” and could explain the apparent lack of deviation from newtonian gravity of ultra diffuse galaxies, it might have deserved more attention.
In this case MOND is being proposed as a way to explain the pattern of orbits of outer solar system bodies. Nothing to do with galactic rotation.
I mentioned galactic rotation curves because thats more or less where it began. If MOND fails to fit the data at those scales, it will necessarily fail within our own solar system at the outer edges where a0 would potentially be relevant.
There are many variants of MOND. RelMOND, for example, includes features that resemble dark matter more closely.
I’m not saying “it’s gotta be MOND”, of course. I’m just reacting to what I perceive as an unnecessarily hostile reaction to it. We have yet to actually figure out dark matter either, after all, and there are many variants of dark matter that have been proposed. So the “it’s designed post facto to fit observations” is a complaint that can be directed against it right now too. I see nothing wrong with exploring all the options, especially when it’s by people who have chosen to spend their efforts doing that for themselves.
None of them are based on anything though. Theyre curve fitting models which is why I am hostile to them. Show me a mechanism that derives what a0 is from scratch.
Basing a model on how well it fits a curve rather than on a mechanism that naturally derives the curve from scratch is essentially worthless.
Without a mechanism that explains why there needs to be a MOND dominated regime in the first place, its just too susceptible to being pathological science.