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2024-11-11

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A cosmology without dark matter (self.science)

submitted 8 months ago by DelightfullyDivisive to c/science

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I haven't found anything calling this crank science, although it does make some rather sweeping claims. One is that dark matter does not exist, and another is that the universe is 27 billion years old.

https://phys.org/news/2024-03-universe-dark.html

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[–] mumblerfish 2 points 8 months ago (1 children)

Well, guess what the Λ in ΛCDM is? They just put it in there to be able to fit the theory to the observation. And it's absurd to say, that they would've found that in the LHC, when they also did not find dark matter particles, even though they are actively looking for those.

Kind of, but also not really. It is a bit different to add a CC which we can implicitly measure the size and equation of state of instead of adding a scalar which we observationally only have a lower bound on the mass on (from not being found in LHC). If their fit makes the mass very high, then they are fine is all I'm saying. The CC and dark matter are different, so yeah, it... would be strange to ask to find the CC att LHC because it did not find dark matter...? What?

It's quite common for research groups to do this, because their work is quite complex and takes time. They proved that their approach might have some merit and now other groups can help them going forward with it.

Absolutely. This is perfectly fine. I'm just saying with how far this direction has come right now, I'm not convinced, but that shouldn't mean much :-)

[–] [email protected] 2 points 8 months ago (1 children)

The point with the LHC is, that it is very hard to find something, that you are not actively looking for. You have to at least have a certain understanding of the decay channels of the proposed particle to be able to scan the data for it. It's the same problem they have for discovering dark matter particles.

[–] mumblerfish 2 points 8 months ago (1 children)

Sure. In model building like this I would assume that you'd make the particle heavy to explain absence from experiments, or you'd make it couple in strange ways. Do the authors here do either? Higgs was hard to find because a little bit of both, dark matter is from the couplings entirely (no coupling to the SM). The scalar, I assume, is not dark matter (that is the claim here), so it must couple to SM so unless heavy it most likely should have shown up at LHC. It is a similar problem, but not the same. If it is the couplings and not the mass that should explain the absence then is there anything in the model that would give a hint to how it couples to anything in the SM? I doubt it, because this is basically pure GR work from what I understand, and not QFT. But, I don't know, I'm just being sceptical here.

[–] [email protected] 1 points 8 months ago (1 children)

I mean, it doesn't have to relate to a particle. Lambda is also associated with a property of space itself.

[–] mumblerfish 2 points 8 months ago

Well... And so can scalars, sure, like in string theory where scalar fields represent various kinds of aspects of geometry of the extra dimensions. But they are, also this scalar, dynamical fields (which the CC is not) and these fields would correspond to "particles". You couple this field to all the other fields of the SM and you get interactions, you have particles. Its a particle.

This is why I know this is generally a problem, in string theory you have all these scalars that comes from compactification, you need to explain why they are not seen by experiments = make them heavy. Otherwise you get new particles, new forces, lots of physics that is not real.