By coincidence, the Sloan Digital Sky Survey just released "the largest three-dimensional map of the universe ever created", advancing cosmology even further to 1 % uncertainty.
"By combining SDSS data with additional data from the Cosmic Microwave Background, supernovae, and other programs, we can simultaneously measure many fundamental properties of the universe," says Mueller. "The SDSS data cover such a large swath of cosmic time that they provide the biggest advances of any probe to measure the geometrical curvature of the universe, finding it to be flat. They also allow measurements of the local expansion rate to better than one percent."
Oddly, the papers seem to have been released to arXiv already before the weekend. The summary paper:
https://arxiv.org/abs/2007.08991 .
- Being an integrative cosmological summary based on the baryonic acoustic oscillations and the cosmic microwave background to establish flatness it reinforces the standard model nicely.
- The structure data in the survey strongly fit dark matter evolving according to general relativity.
- The flatness of space is now 10^-4 - yielding a universe volume at least 100 million times larger than the observable - which is just an order of magnitude from the detection limit.
- Dark energy can be detected at 8 sigma based on accepting flatness, it is constant and yields a current expansion rate at H0 = 68.20 +/- 0,81 km s^-1 Mpc^-1. This likely means no physics since it is < 72 km s^-1 Mpc^-1 at nearly 3 sigma.
Most exciting to me is that it is consistent with simplest selection bias ("anthropic") finetuning which they point out as possible and substantially strengthened explanation.
"Nevertheless, the observed consistency with flat ΛCDM at the higher precision of this work points increasingly towards a pure cosmological constant solution, for example, as would be produced by a vacuum energy finetuned to have a small value. This fine-tuning represents a theoretical difficulty without any agreed-upon resolution and one that may not be resolvable through fundamental physics considerations alone (Weinberg 1989; Brax & Valageas 2019). This difficulty has been substantially sharpened by the observations presented here."
[The paper describes more data products on Github in case someone wants to look at the analysis and raw data.]
More here:
https://www.bnl.gov/newsroom/news.php?a=117340 ,
https://www.port.ac.uk/news-events-...1-billion-years-of-universe-expansion-history .