Galaxy Formation
Galaxy formation is the process by which galaxies assemble and evolve in the universe, beginning shortly after the Big Bang and continuing to the present day. The formation and early development of galaxies remains a central question in cosmology, as observations reveal galaxies existed when the universe was only a few hundred million years old—earlier than many theoretical models predicted. Understanding how these first galaxies formed, what composed them, and how they grew over cosmic time requires both observational data and sophisticated computational simulations.
Early Galaxy Formation
The earliest galaxies appear to have formed within the first billion years of cosmic history. These primordial galaxies were likely smaller and less chemically enriched than modern galaxies, assembled from cold dark matter and primordial hydrogen and helium. The James Webb Space Telescope has recently provided observations of exceptionally distant galaxies, including GN-z11, that offer insights into this epoch. Evidence suggests that some of these early galaxies may have contained Population III stars—the universe’s first generation of stars, composed almost entirely of hydrogen and helium with no heavier elements.
Ongoing Evolution
Galaxies have undergone substantial changes since their formation. Through mergers, collisions, and the accumulation of gas and stars, galaxies have grown larger and more massive. Star formation rates have generally declined over cosmic history, with the peak of star formation occurring roughly 2-3 billion years after the Big Bang. Present-day observations across multiple wavelengths continue to refine our understanding of the physical processes governing galaxy assembly and the role of supermassive black holes, supernovae, and other feedback mechanisms in galaxy evolution.
Source Notes
- 2026-04-12: Possible Discovery of First Ever Stars in the Universe
- 2026-04-20: Galaxy Clusters Underestimated Baryonic Matter Challenges Dark Matter · ▶ source