Comment by Sniffnoy
4 hours ago
It bugs me that articles about dark matter so frequently frame things as dark matter vs. MOND, and don't consider any of the other theories of modified gravity. I think MOND is just not a great theory and it has a lot of evidence against it by this point; but other theories of modified gravity have not, to my knowledge, been tested to the same extent, nor do they get anywhere near the publicity. Dark matter still seems more likely than modified gravity, but I wish they wouldn't emphasize MOND so much as the representative of modified gravity, and I wish we'd hear more about tests of other modified gravity theories!
The problem with any theory of modified gravity is that there is just no physical justification for it. It's only motivation seems to be to explain away dark matter by adding and tweaking free parameters until you fit the data, which you can always do given enough variables.
van Neumann's quote comes to mind - "With four parameters I can fit an elephant, and with five I can make him wiggle his trunk."
Hm, MOND is full of new parameters (an entire interpolation function!), but do other modified gravity theories really have so many? I guess actually I don't know the answer to that, maybe they do. Do you know how many others have?