/sci/ - Science & Math

>>12691818
>Key point, we started measuring the CMB well before dark matter theories started (let alone CDM getting traction).
Not the powerspectrum. There were no precise measurements of the powerspectrum until WMAP year 1 in 2003. This is well after CDM was established. Here is a figure of the state-of-the-art measurements in 1995. As you can see the prediction predates the measurements.
>gravitation lensing does still happen in places where it shouldn't
Lensing in the Bullet Cluster does not follow the distribution of normal matter. Most of the baryons are in the intra-cluster medium, which has been stripped out. CDM does not predict huge halos without galaxies, if that's what you're implying.
>IMO dark matter is probably something that we already know about, be it some kind of cold dense plasma, neutrinos, or something else gay like gravitation wave constructive interference on a galactic scale.
It being plasma would violate primordial nucleosynthesis and CMB constraints. Not to mention the fact that baryon only cosmology predicts a totally wrong distribution of matter in the modern universe. https://arxiv.org/abs/1112.1320
Cold plasma is also detectable through absorption against quasars.
Neutrinos aren't massive enough, and they're constrained by the CMB and matter power spectrum.
Gravitational waves also wouldn't work because it would be diluted too quickly with the expansion of the universe.
None of these would work without rewriting cosmology completely. It's totally illogical dismiss dark matter as "unlikely" while requiring a massive hand-wave for any of these to be remotely salvageable.

>>12649726
>>12649652
Here's an even better example from 1995.

>>12003711
>I don't know what you mean by the "form" of the angular features in the characteristic temperature fluctuations.
The shape of the curves in the powerspectrum. You don't need to know the absolute scale to predict the shape of the powerspectrum.

>I remember there were basically three possible outcomes: angular scale less than one degree, about one degree, and greater than one degree
Think about what you're saying though. The angular scale of what? The angular scale of the first peak. Why was a peak expected? Because it was predicted from theory. So was the existence of the other peaks. That was a big prediction. Changing the absolute scale just shifts the peaks left and right, but the overall shape remains the same.

>All of the power spectrum predictions were phenomenological in nature
Wrong. See the paper I attached. That is a description of how to calculate the prediction from theory. Most of the structure hand't been measured by then.

>constraining the predictions by very many previous experimental results, iirc
Also wrong. See my figure. That is from 1995. Note that the powerspectrum shown from theory is almost exactly what is found today. The figure also shows all the observational data at the time. There is no way the curve could be guessed just based on the observations. This was a prediction.

You're ranting and raving about the scale but that is not the point I'm making, at all. I've made that very clear. The absolute angular scale is literally just a single datapoint.