The Big Bang theory is currently the leading scientific explanation for the origin and development of the universe. It is supported by a vast amount of observational and theoretical evidence gathered over many decades. While it is impossible to assign an exact numerical likelihood to its correctness, it is widely accepted and considered highly probable by the scientific community based on the following factors:
Observational Evidence: Astronomers have observed the redshift of distant galaxies, which indicates that the universe is expanding. This expansion is a key component of the Big Bang theory. Additionally, the detection of cosmic microwave background radiation, which is the remnants of the early universe, provides further evidence in support of the theory.
Hubble's Law: Edwin Hubble's observations of the redshift of galaxies led to the formulation of Hubble's Law, which states that the farther away a galaxy is, the faster it is moving away from us. This observation supports the idea of an expanding universe, as predicted by the Big Bang theory.
Abundance of Light Elements: The Big Bang theory successfully predicts the observed abundance of light elements in the universe, such as hydrogen and helium. The theory suggests that these elements were formed during the early stages of the universe, and their predicted abundance matches the observations.
Cosmic Microwave Background Radiation: The discovery of the cosmic microwave background radiation in 1965 provided strong support for the Big Bang theory. This radiation is a faint glow that permeates the entire universe and is considered a remnant of the early stages of the universe, when it was hot and dense.
Consistency with General Relativity: The Big Bang theory is consistent with Einstein's theory of general relativity, which describes the gravitational behavior of massive objects and the structure of the universe on a large scale. General relativity has been extensively tested and validated through numerous experiments and observations.
While scientific theories are always subject to refinement and revision as new evidence emerges, the Big Bang theory has withstood rigorous scrutiny and is supported by a wide range of empirical evidence. Therefore, based on the available evidence, the Big Bang theory is considered highly likely to be an accurate description of the early universe.