https://alvinng4.github.io/grav_sim/examples/cosmic_structur...
These simulations take their simple initial conditions from the Cosmic Microwave Background fluctuations, but models without dark matter fail to match the observed CMB. There are no major baryon-only simulations because cosmology doesn't work without DM, and you have nothing to start from. You need a quantitative model which works on some level to even begin, people have tried with modified gravity models.
Apologies, I know this is typically considered bad form, but have you gotten to the following section in the article?[2] It appears to directly contradict your claims.
> MOND’s also been around since the early 1980s, but, in 2021, it finally developed a model – the Aether-Scalar-Tensor framework, or AeST – which ALSO maps perfectly onto the acoustic peaks revealed by WMAP and Planck. (It does it by proposing a new vector field and scalar field that duplicate the effects of Cold Dark Matter in the early universe...
[0] https://astro.theoj.org/article/93065-an-analytic-model-for-...
[1] https://www.caltech.edu/about/news/cosmic-simulation-reveals...
[2] https://theeggandtherock.com/i/158515951/more-matter-or-less...
> MOND’s also been around since the early 1980s, but, in 2021, it finally developed a model – the Aether-Scalar-Tensor framework, or AeST – which ALSO maps perfectly onto the acoustic peaks revealed by WMAP and Planck. (It does it by proposing a new vector field and scalar field that duplicate the effects of Cold Dark Matter in the early universe
This doesn't contradict what I said. These models are not simply removing DM, I said people have tried with modified gravity models like these. First the models which fit the CMB were engineered to do, and each model has many more free parameters than dark matter. And note they have replaced invisible matter with an invisible matter-like field, it's not a simplification. Remembering that cold dark matter predicted these features, with fewer parameters and it is a physical model, not merely a fit. People have run simulations with the more basic MOND models, to find it cannot form realistic structure. Generally it forms structure more quickly than standard cosmology. Finding they need to add dark matter to their already modified gravity models to get something reasonable.
https://arxiv.org/abs/2007.00555
> Generally [MOND] forms structure more quickly than standard cosmology.
Magnetohydrodynamics, not just hydrodynamics. It would need some type of restoring force similar to how the black hole simulation was found to behave when it included magnetic fields.
> People have run simulations with the more basic MOND models, to find it cannot form realistic structure.
Neither does ΛCDM though, right? It matches the CMB, sure, but it doesn't match the many of the observed properties of the universe either. The observed voids and over-densities are significantly larger than predicted, nor is the observed distribution of dark matter in galaxies what we predict.
> And note they have replaced invisible matter with an invisible matter-like field, it's not a simplification.
Great point, and I'm happy to admit I missed this.
But I'm not actually a proponent of MOND, nor even an opponent of ΛCDM. It's the best we got. I just feel it's not quite as accepted as current consensus seems to, so I'm glad there's people out here still trying to poke holes in it and find alternatives.
> These simulations have a lot of value, they demonstrate that standard cosmology and normal gravity has no problem forming voids and filaments.
That being said, I think the author intends for this article to be more of a call to action than an actual result. Simulations aren't cheap, somebody needs to actually do the work. The point that there aren't any simulations without dark matter is an important one too.