What cosmological model describes the expansion of the universe from a hot, dense state?

The Big Bang Theory is the widely accepted cosmological model that describes the expansion of the universe from an initial hot and dense state. According to this theory, the universe started as a singularity approximately 13.8 billion years ago, followed by rapid expansion. This expansion led to the cooling of the universe, allowing for the formation of atoms, stars, galaxies, and eventually the large-scale structure we observe today.

The theory is supported by several key pieces of evidence, including the cosmic microwave background radiation, which is the afterglow of the initial heat and density, and the observed redshift of distant galaxies, which indicates that the universe is continually expanding. Thus, the Big Bang Theory provides a comprehensive framework for understanding the origins and evolution of the universe in a way that aligns with both observational data and theoretical physics.