[CorrectHorseBat]

I remember reading/hearing somewhere that the bullet cluster actually fits MOND better than dark matter. I think it was a video by Sabine Hossenfelder but I can't find it right now and I'm not qualified to say whether it made sense or not.

[throwawaymaths]

Bullet cluster is inconsistent with LCDM on the grounds that given the apparent dark matter:matter ratio a collision between clusters of that size is something like unlikely to the tune of one in a trillion? IIRC universes. (Aka the collision should not have happened in the first place).

The thing about lensing is that we don't have a solution in (GR would need to be tweaked if MOND is true -- the math is much harder!!) so we can't really say what the lensing would look like in any given MOND-like theory yet. Seems weird to declare that MOND can't explain lensing. It's should be more qualified: "we don't think MOND can explain the lensing"

[naasking]

It's not clear that GR would need to be tweaked to match MOND. The GR solutions we currently use in LCDM are based on the FLRW metric, but that metric could just be the wrong fit for our universe.

[mr_mitm]

How is it not clear? GR reduces to Newtonian gravity in the weak field limit, which MOND is explicely not. If MOND is true, then GR is wrong.

[throwawaymaths]

Have some nuance. GR is already known to be "wrong" since it isn't reconcilable with QM.

If any given MOND is true, GR needs some (possibly minor) changes in the limit, just as GR needs (possibly minor) changes to accommodate QM