alkuräjähdysteoria

Alkuräjähdysteoria, known in English as the Big Bang theory, is the prevailing cosmological model for the universe's earliest known periods and its subsequent large-scale evolution. It postulates that the universe began as an extremely hot, dense point that expanded rapidly and continues to do so today. This initial expansion is thought to have occurred approximately 13.8 billion years ago.

The theory is supported by a significant body of observational evidence. The most compelling evidence includes the observed expansion of the universe, as evidenced by the redshift of distant galaxies, which indicates they are moving away from us. Another key piece of evidence is the cosmic microwave background radiation (CMB), a faint glow of radiation that permeates the entire universe. This radiation is interpreted as the afterglow of the Big Bang. Furthermore, the observed abundance of light elements, such as hydrogen and helium, in the universe closely matches the predictions made by Big Bang nucleosynthesis models.

While the Big Bang theory describes the evolution of the universe from a very early, hot, and dense state, it does not explain what caused the initial event or what existed before it. These questions remain active areas of research and speculation in cosmology and theoretical physics. The theory has undergone refinements over time, incorporating concepts like cosmic inflation to address certain observational anomalies.