Unveiling Galaxy Sizes: A Response to Lisle's Critique of JWST Data and Cosmological Interpretation

Luke Barnes's article, "Size of Galaxies in JWST Data and Cosmology—Reply to Lisle," addresses a specific criticism leveled by Jason Lisle concerning the interpretation of galaxy sizes observed by the James Webb Space Telescope (JWST) and their implications for cosmology, particularly the Big Bang model. Barnes's response is a detailed and technical rebuttal, aimed at clarifying the scientific understanding of galaxy formation and the challenges in interpreting observational data.

Lisle's argument, typical of young-earth creationist critiques, centers on the apparent "maturity" and size of galaxies observed at high redshifts (i.e., very distant and thus seen as they were in the early universe). He contends that these galaxies appear too large and developed for the time elapsed since the Big Bang, as calculated by standard cosmological models. This, he argues, undermines the Big Bang and supports a young-earth timescale.

Barnes's response is structured to systematically dismantle Lisle's claims, focusing on several key points:

1. Redshift and Lookback Time: Barnes begins by reiterating the established relationship between redshift and lookback time. He emphasizes that higher redshift objects are indeed seen as they were in the early universe, but this does not automatically imply they must be small or underdeveloped. He stresses that the interpretation of these observations requires a nuanced understanding of galaxy formation.

2. Surface Brightness Dimming: A crucial aspect of Barnes's argument is the concept of surface brightness dimming. Due to the expansion of the universe, the light from distant galaxies is stretched, resulting in a decrease in surface brightness. This means that distant galaxies appear fainter and potentially smaller than they would if they were closer. Lisle, according to Barnes, overlooks or misunderstands this effect, leading to inaccurate size estimations.

3. Galaxy Formation Models: Barnes explains that galaxy formation is a complex process involving the accretion of gas, star formation, and mergers. He highlights that simulations and theoretical models predict the formation of relatively large galaxies even at early epochs, albeit with different characteristics than those seen in the local universe. These models account for the hierarchical growth of galaxies over time.

4. Observational Challenges: Barnes points out the inherent challenges in measuring the sizes of distant galaxies. Factors such as atmospheric seeing, instrument resolution, and the selection of specific wavelengths can influence size measurements. He emphasizes that JWST, while providing unprecedented detail, still presents challenges in accurately determining galaxy sizes, particularly at high redshifts.

5. Selection Effects and Statistical Significance: Barnes argues that Lisle's selection of specific galaxies to support his argument may be biased. He stresses the importance of considering statistical samples and accounting for selection effects when drawing conclusions about galaxy sizes. He suggests that Lisle might be focusing on outliers or galaxies with unusual properties, rather than representative samples.

6. Interpretation of "Maturity": Barnes addresses Lisle's claim that distant galaxies appear too "mature." He clarifies that "maturity" in this context refers to the presence of well-formed disks or bulges, which can arise through various processes, including mergers and rapid star formation. He argues that these features do not necessarily imply a long evolutionary timescale.

7. Misunderstanding of Cosmological Principles: Barnes suggests that Lisle's critique stems from a fundamental misunderstanding of basic cosmological principles, such as the expansion of the universe and its effects on light propagation. He emphasizes that these principles are well-established and supported by a wealth of observational evidence.

8. The Importance of Scientific Consensus: Barnes implicitly highlights the importance of scientific consensus. While acknowledging that scientific understanding is constantly evolving, he emphasizes that the Big Bang model and the standard cosmological framework are robust and well-supported. He contrasts this with the lack of scientific support for young-earth creationism.

In conclusion, Barnes's article is a detailed and technical response to Lisle's critique, aiming to clarify the scientific understanding of galaxy sizes in the early universe. He emphasizes the importance of considering factors such as surface brightness dimming, galaxy formation models, and observational challenges when interpreting JWST data. He argues that Lisle's claims are based on misunderstandings and misinterpretations of cosmological principles and observational evidence. Barnes's work seeks to defend the scientific integrity of cosmological research and to promote a more accurate understanding of the universe.