A recent study suggesting that the Universe is decelerating has drawn criticism from prominent astrophysicist and Nobel Laureate Adam Reiss. Reiss, who won the 2011 Nobel Prize in Physics for his work on cosmic expansion, highlighted several significant flaws in the claims made by the authors of the study, which is based on observations of approximately 300 supernovae.
The original paper posits a correlation between the peak brightness of Type-Ia supernovae and the age of their host galaxies. The authors argue that younger galaxies exhibit dimmer supernovae, leading to the conclusion that current methods for measuring galactic distances are flawed. This claim challenges the widely accepted ΛCDM model, which posits that the Universe is expanding at an accelerating rate.
Reiss points out that while the paper has undergone peer review, it contains critical inaccuracies. One major concern revolves around the issue of determining galactic ages. The authors assert that the light curves of Type-Ia supernovae do not account for the ages of their host galaxies. While this statement is partially true, Reiss emphasizes that these light curves do consider galactic mass, which is more straightforward to measure than age.
Most modern studies, including the Pantheon+ catalog, adjust for the mass of a supernova’s host galaxy. This adjustment is crucial as it serves as a reliable proxy for age. The authors of the deceleration study, however, relied on older databases that lacked this mass adjustment, raising questions about the validity of their findings.
Another significant flaw identified by Reiss pertains to the relationship between the age of a galaxy and the age of its progenitor stars. The authors focus on the measured age of host galaxies but neglect to consider the age of the progenitor stars of supernovae, which remains difficult to ascertain accurately. By assuming that a progenitor star forms concurrently with its host galaxy, the authors conclude that distant supernovae progenitors are younger than those of nearby supernovae. This assumption is problematic, as local supernovae are often found in regions of active star formation, indicating that Type-Ia supernovae typically occur less than a billion years after their progenitor stars form.
Reiss articulates that the foundation of the study’s argument is weak, as the link between galaxy age and progenitor age is not robust. He anticipates further peer-reviewed research to address these issues more comprehensively.
As the scientific community continues to engage with the findings of the decelerating Universe study, it is evident that significant scrutiny remains. The discussion surrounding cosmic expansion and its implications for our understanding of the Universe is far from over.
For further reading, relevant studies include the works of Son et al. published in the Monthly Notices of the Royal Astronomical Society, and several articles in The Astrophysical Journal that discuss supernova brightness and host galaxy mass. These resources provide additional context and data for ongoing investigations into this complex field of study.
