This thread discusses the implications of a recent paper on supernova cosmology, particularly focusing on the relationship between Type Ia supernova luminosity and progenitor age. The conversation explores the potential biases introduced in cosmological measurements due to this relationship and its impact on the understanding of the universe's expansion, including the role of dark energy.
Participants do not reach a consensus on the implications of the new findings for existing cosmological models. There are competing views on the validity of the assumptions made in previous studies and the potential need to revise interpretations of dark energy and the universe's expansion.
Some discussions reference the need for a deeper understanding of the technical details presented in the paper, indicating that not all participants may have the requisite background to fully engage with the material.
This discussion may be of interest to those studying cosmology, particularly in relation to supernovae, dark energy, and the evolution of the universe's expansion history.
Ah, thank you! That was basically my guess but I didn't want to assume.PeterDonis said:That shouldn't be possible with a cosmological constant, because the energy density of matter and radiation can only decrease with expansion, so once the universe has expanded to the point where the cosmological constant dominates, it should keep dominating (i.e., expansion should keep accelerating) forever after that.
Yeah that's what I was getting at. Hopefully we'll get some interesting responses/rebuttals in the coming months.PeterDonis said:In other words, IMO that pattern of accelerated expansion starting 7 bya and then stopping 2 bya is a reason to doubt that the findings of this paper are actually valid.