Observational evidence of a BIG BANG Theory
Observational evidence The earliest and most direct observational evidence of the validity of the theory are the expansion of the universe according to Hubble's law (as indicated by the redshifts of galaxies), discovery and measurement of the cosmic microwave background and the relative abundances of light elements produced by Big Bang nucleosynthesis . More recent evidence includes observations of galaxy formation and evolution , and the distribution of large-scale cosmic structures , These are sometimes called the "four pillars" of the Big Bang theory. Precise modern models of the Big Bang appeal to various exotic physical phenomena that have not been observed in terrestrial laboratory experiments or incorporated into the Standard Model of particle physics . Of these features, dark matter is currently subjected to the most active laboratory investigations. Remaining issues include the cuspy halo...