Probing Cosmic Expansion: The Cosmological Implications of Redshift

Understanding the stretching of light wavelengths, or redshift, is essential for unraveling cosmic expansion and the structure of the universe. This paper investigates three redshift mechanisms: Doppler, cosmological, and relativistic redshift in the context of general relativity. While Doppler redshift applies primarily to nearby objects, cosmological redshift, governed by the expansion of the universe within the Friedmann-Lemaître-RobertsonWalker (FLRW) metric, becomes essential at cosmological distances, supporting the Big Bang model. The work of Edwin Hubble, which linked galaxy recessional velocities to their distances in what is now known as the Hubble-Lemaître law, provided a framework for measuring the expansion rate of the universe. Persistent discrepancies in this rate termed the “Hubble tension,” continue to inspire debate and investigation. Additionally, this paper highlights essential distance measurement methods used in redshift analysis. Technological advancements, including the James Webb Space Telescope (JWST) and the Dark Energy Spectroscopic Instrument (DESI), are enhancing redshift accuracy, fostering new insights into dark matter, dark energy, and galaxy evolution, as well as probing the fundamental questions of the universe.