Big Bang Theory Science
The Big Bang theory offers a comprehensive explanation for a broad range of observed phenomena, including the abundance of light elements , the CMB , large-scale structure , and Hubble's law .  The theory depends on two major assumptions: the universality of physical laws and the cosmological principle . The universality of physical laws is the underlying principle of the theory of relativity . The cosmological principle states that on large scales the universe is homogeneous and isotropic .