Elise Crull (CCNY)
4-6pm, Tuesday April 10, CUNY room 5307 (365 5th Ave, New York NY).
Title: Questioning the Evidence for Cosmic Expansion.
Abstract: expansion is a key feature of the standard cosmological model, yet evidence for it is not as strong as often believed. The only direct evidence is galactic red-shifting, but reasoning from these data to expansion is not straightforward. I argue that the relationship is better understood as inference to the best explanation, and granting this, that expansion is not the obvious best explanation. This is demonstrated by investigating the fitness of the ΛCDM model as against static models under various indirect tests.
In this talk I shall focus on time dilation studies: if expansion is happening, then general relativity suggests that clocks in substantially red-shifted galaxies ought to run slow with respect to the local frame. I briefly discuss the potential threat of selection bias in Type Ia supernovae time dilation tests, and evaluate the research methods employed by those assessing the mysterious lack of time dilation in gamma-ray bursts and quasars.
If expansion is not the best explanation for the relevant data, then one can motivate certain normative claims about methodological shifts in contemporary cosmology. To wit—more thought should be dedicated to alternate explanations for red-shifting phenomena, and to the development and careful analysis of indirect tests for expansion as against alternative cosmological models.