[dogma1138]

Is that true? This would be the first time I’ve heard that, neutrinos don’t interact really with anything other than gravity and via the weak force… in fact I’m not sure if “interacting” with gravity is even the right way to look at things photons interact with gravity but they don’t have any mass.

So at best their axiom might be that if it has mass it interacts with electromagnetism which we already know not to be be true in all cases.

[ianburrell]

Neutrinos interact with barionic batter through weak nuclear force. Dark matter can't be normal neutrinos because they move at close to light speed and we know that dark matter is cold, slow moving. The best dark matter candidate are WIMPs which only interact with gravity and weak force. Heavier, unknown neutrinos are possibility but would mess up Standard Model.

There are detectors that are trying to find weak force interactions. They haven't found anything yet which is constraining paramters of dark matter particles.

[dogma1138]

I didn’t think neutrinos are a good candidate for dark matter despite being wimps all I said is that this is the first time I heard of that people who don’t accept dark matter think that interaction with ‘gravity’ requires also interaction with electromagnetism despite us having pretty solid examples of things that we know for sure that they exist that do not follow that requirement.

[consilient]

> Is that true?

They're not literally thinking those thoughts in those terms, it's just what pops out when you try to translate complaints about "tangibility" and "seeing things directly" from folk-physical intuition into something physically meaningful.

[dogma1138]

I’m not sure I’m following, are you saying that the likes of Milgrom have difficulties articulating their thoughts?

[consilient]

No, I'm just talking about the local commentariat. Milgrom's reasons for holding out (all the other MOND people are MOND + DM people now; the Bullet Cluster was a death blow for pure MOND) are presumably more idiosyncratic.

[dogma1138]

Still doesn’t align with the original assertion that dark matter “deniers” assert that interaction with gravity requires interaction with EM.

Currently I would group the “dark matter” into 3 camps, dark matter as a new form particles, dark matter as a combination of any sort of existing particles and matter e.g. wimps, primordial blackholes, brown dwarfs, cold baryonic matter etc. and dark matter as modified gravity this is MOND and TEVES et al.

None of which as far as I know make a statement around having to have interaction with EM if you are interacting with gravity.

[zinclozenge]

General relativity links geometry to the stress energy tensor, so even if photons are massless I don’t think calling the effect “interaction” is necessarily wrong.

[dogma1138]

Well gravity isn’t a force or at least not on the same level of other forces which the interaction with is mediated by a force carrying particle.

How gravity works in GR is more like a topological property of space time rather than say like the electromagnetic force which is why I was asking about what exactly they mean by interacting with gravity.