A recent study claiming that the Universe is decelerating has sparked significant interest among astronomers. This research, which suggests fundamental flaws in the current understanding of cosmic expansion, has drawn the attention of notable physicist Adam Reiss, who received the 2011 Nobel Prize in Physics for his work on the accelerating universe. Reiss has highlighted critical issues with the methodology and conclusions of the study, which are based on observations of approximately 300 supernovae.
The authors of the controversial paper assert that they have identified a correlation between the peak brightness of Type-Ia supernovae and the ages of their host galaxies. They argue that younger galaxies produce dimmer supernovae, leading to a reevaluation of galactic distances. This claim implies that the standard cosmological model, known as ΛCDM, is incorrect, suggesting instead that the Universe is decelerating. While the paper has undergone peer review, Reiss points out major flaws that could undermine its conclusions.
One primary concern raised by Reiss is the issue of determining galactic ages. The authors argue that the light curves of Type-Ia supernovae do not account for the ages of their host galaxies. While there is some validity to this claim, Reiss notes that these supernovae do consider galactic mass, which is much easier to measure. Accurate age determination of a galaxy can be complex and model-dependent, leading to potential inaccuracies. Modern catalogs, such as Pantheon+, adjust supernova data for mass, as studies indicate that galactic mass serves as a reliable proxy for age.
The authors of the new paper relied on older databases that did not incorporate mass adjustments, raising concerns about their approach. If the aim is to challenge established theories, Reiss suggests that using outdated data is problematic.
Reiss also critiques the connection made between the age of host galaxies and the progenitor stars of supernovae. The study predominantly uses the measured age of host galaxies as a stand-in for the age of the progenitor stars, assuming that these stars formed concurrently with the galaxies themselves. This assumption is questionable, as local supernovae are often found in regions of active star formation, indicating that the progenitors may be relatively young. Research has shown that Type-Ia supernovae typically occur less than one billion years after their progenitor stars form, thereby casting doubt on the authors’ foundational argument.
Reiss advises caution regarding the findings in this paper, suggesting that further peer-reviewed studies will likely address these and other issues. He expresses confidence that the scientific community will soon clarify the complexities surrounding this topic.
As the debate continues, the dialogue among physicists and astronomers remains crucial in understanding the nature of the Universe. The interplay of new research and established theories will shape future inquiries into cosmic dynamics.
For those interested in the original study, it is titled “Strong progenitor age bias in supernova cosmology–II. Alignment with DESI BAO and signs of a non-accelerating universe,” published in the Monthly Notices of the Royal Astronomical Society. Additional references to relevant studies include works published in The Astrophysical Journal that explore the relationship between host galaxy mass and supernova brightness.
