Wide binaries offer a means to test Modified Newtonian Dynamics (MOND), an alternative explanation for galactic rotation curves compared to dark matter. Various analyses of wide binary systems using Gaia DR3 data are in conflict, with some favoring MOND and others favoring General Relativity (GR). Will future analyses using Gaia DR4 data align more consistently with MOND than with GR?
This question resolves as YES if all the most methodically robust analyses of wide binaries, using Gaia DR4 data, exhibit discrepancies with GR that are in line with MOND.
This question resolves as NO if the analyses of wide binaries using Gaia DR4 data are aligned with GR, or if most of the methodically robust analyses do not agree on whether the Gaia DR4 data is consistent with GR.
Determining the resolution of this question necessitates a judgment regarding the methodical robustness of different analyses. I intend to consider informed discussions in the comments while ultimately reserving final judgment.
Related questions
Slightly related: Stacy has a new blog post on what the Gaia data has to say about the amount of mass in the milky way:
This is a good summary of the tensions and why Chae and Hernandez are likely to win the argument:
https://twitter.com/8minutesold/status/1667141734055264256
@AdamTreat I'm in it for the long haul. I think wide binaries are going to end up being strong evidence for MOND or the necessity of MOND-like dynamics in whatever the eventual solution to the dark matter problem is. It won't be conclusive evidence, but it is going to be a net win which I think will make this a YES.
I think DR4 is a red herring. We already have enough data with DR3 and disagreement is mainly systematic not statistical. I expect Hernandez, Pittordis & Sutherland, and Chae to get the basically same result with DR3 and DR4 unless they change their methodologies.
Personally I think Hernandez's criticism of Pittordis & Sutherland is sound, and two completely different analyses (Hernandez and Chae) arriving at the same conclusion is quite convincing.
So this market is about how methodological disputes will be settled, with somewhat unrelated and awkward endpoint coincidental with DR4. DR4 does have a good advantage in that it is almost certain everyone will repeat analyses with DR4.
@SanghyeonSeo and @AdamTreat I agree that this market is mostly about methodology but I still think that there is some merit in waiting for Gaia DR4.
One is just that I don’t want to be too hasty about judging this methodological dispute and Gaia DR4 is a convenient Schelling point. But I also think that in general having more and better data is often helpful in resolving systematics. For example if cuts used in the Hernandez and Chae analyses where not as effective as expected at removing contamination from un-bound and triple systems that might be apparent with Gaia DR4 data.
Overall I agree that Hernandez has a better methodology than Pittordis & Sutherland but I also worry that the analyses was not blinded and might be sensitive to the specific cuts he used. Using Gaia DR4 does not completely address this but it might ameliorate it to the extent the result reflects statistical fluctuations in Gaia DR3.
To make this more objective I would have gone with the three Gaia DR4 analysis right now. Currently, to my recollection there are three that are peer reviewed. Two agree with eachother and these support MOND. The outlier uses more data however and doesn't support MOND.
A very objective resolution criteria would be whether the authors of these three papers move towards MOND: ie, if the outlier shifts to reconcile in a way that supports MOND or if they move away from MOND: ie, if one or more of the two that now support MOND end up moving away from it towards the outlier.
If you think this a better resolution criteria, you could pause the market and switch if all current betters agree? Regardless, I'll take a small YES side of this bet and thanks for the market!
