Speculations In Big Bang
Main article: Cosmogony While the Big Bang model is well established in cosmology, it is likely to be refined. The Big Bang theory, built upon the equations of classical general relativity, indicates a singularity at the origin of cosmic time; this infinite energy density is regarded as impossible in physics . Still, it is known that the equations are not applicable before the time when the universe cooled down to the Planck temperature , and this conclusion depends on various assumptions, of which some could never be experimentally verified. (Also see Planck epoch .) One proposed refinement to avoid this would-be singularity is to develop a correct treatment of quantum gravity . It is not known what could have preceded the hot dense state of the early universe or how and why it originated, though speculation abounds in the field of cosmogony . Some proposals, each of which entails untested hypotheses, are: M...