The crisis in cosmology

[Gmetric]

A good one from Dr Becky

[Lady Fraktor]

A interesting and entertaining video.
Thank you Arry

[Graeme1858]

Good one Arry, cheers.

It will be interesting to see what the JWST data shows us.

Graeme

[pakarinen]

Ruh roh.

[jrkirkham]

Thank you. That is an entertaining video and easy to understand.

[SkyHiker]

So, the simplest possible cosmological model is not good enough. These results put another nail in the coffin of the cosmological principle, which all cosmological models are based on. Feynman called it an absurdity long ago already. Dropping it will be a complete overhaul. Hopefully the JWST will provide a lot more evidence soon.

[pakarinen]

One wonders how many discrepancies (large or small) have to pop up before there's a paradigm change. I guess we have to wait and see.

[Gmetric]

So, the simplest possible cosmological model is not good enough. These results put another nail in the coffin of the cosmological principle, which all cosmological models are based on. Feynman called it an absurdity long ago already. Dropping it will be a complete overhaul. Hopefully the JWST will provide a lot more evidence soon.

Hey Henk, thanks for the response. I think perhaps you are jumping the gun just a little. Technically, as it stands, there aren't really any "nails" in the "coffin" for the ΛCDM cosmological model. There are a few clues that hint at some problems and one crack in the model, which is definitely not a crisis. The evolution of stars, galaxies, massive galaxies, proto-galactic clusters and fully-fledged clusters happens consistently with theoretical predictions. Reionization, on average, is completed when the Universe is approximately 550 million years old, which matches theoretical predictions. Cosmic microwave background radiation fluctuations are slightly lower in magnitude than expected but are consistent with cosmic variance and theoretical predictions with a confidence level of 95%. Okay, there aren't any angular correlations, but that is, as expected, to a relatively high confidence level, just two sigma, which is acceptable in astronomical theory. Colliding galaxy clusters show a clear separation between where the ordinary matter is and the mass. For isolated clusters, gravitational lensing data requires not just dark matter but also a clumpy substructure to exist within those dark matter haloes. Galaxies moving within clusters require dark matter, and the internal motions of stars within galaxies require something else: MOND, which doesn't work for the larger scales or dark matter, which fits. Recent claims that “wide binary stars support modified gravity” have proven grossly overestimated or wrong. At best, and in my humble opinion, I'd say that these are clues that the current working model needs more work and nothing more.

The only thing one could legitimately call a crack is the discrepancies between the current methods used to calculate the Universe's expansion. The early relic method (baryon acoustic oscillations in the Universe’s large-scale structure and the peak fluctuation scale in the cosmic microwave background) which sits at 67 km/s/Mpc, and the distance ladder method which sits at ~73 km/s/Mpc. This "Hubble tension" isn't so much a crack in the ΛCDM cosmological model but rather a consequence of our inability to find a solution for the disagreement.

Now, I'm certainly not going to sit here and say that it is perfect because it is far from that, but thus far, it has proved to be quite successful in predicting various observations. The problems may be resolved with adjustments as opposed to a paradigm shift; that's not to say that it is implausible that a paradigm shift may be better than what we have. Nevertheless, paradigm shifts require substantial changes in what is currently known, for example, the Ptolemaic system to the Copernican system or Newton to Einstien(not really a paradigm shift but a leap in understanding IMHO), so while I fully expect changes, I think it might be a tad early to burry ΛCDM cosmological model, just yet. But maybe next month, lol

[pakarinen]

Fixed it! Well, part of it... Maybe...
https://academic.oup.com/mnras/article/ ... login=true