What happened at the beginning of the big bang theory?

Answer 1

The beginning of the Big Bang creation event will always remain hypothetical as extrapolation of the expansion of the Universe backwards in time and possible observational evidence is limited to the Cosmic Microwave Background Radiation barrier. The initial condition of the singularity, as the impetus of the Big Bang, is the unknowable conjecture of infinite density and temperature at a finite time in the past. How closely we can extrapolate towards the singularity is debatable; certainly no closer than the end of the Planck epoch. This singularity is sometimes called "the Big Bang", but the term can also refer to the early hot, dense phase itself, which can be considered the "birth" of our Universe. The earliest phases of the Big Bang are subject to much speculation. In the most common models the Universe was filled homogeneously and isotropically with an incredibly high energy density and huge temperatures and pressures and was very rapidly expanding and cooling. Approximately 10−37 seconds into its evolutionary expansion, a phase transition caused a dimensional inflation, during which the Universe grew exponentially into the existence of our traditional fourth dimensional SpaceTime continuum.

Note: The analogous expression of the pre-Big Bang singularity as a conceptual mass (or matter) with size, density, and time at the beginning of SpaceTime (i.e. extremely small) is irrelevant due to the evolving dimensional unfolding of the singularity. This singularity is defined as that dimensional condition which ingratiated the entirety of our universe (the four combined forces of nature; strong nuclear, weak nuclear, electromagnetic and gravity). Therefore the concept of size has no meaning within this singular event known as the Big Bang. It is expected that all of the matter and energy retained for our universe was provided upon this singular event. While the amount of this combined retained matter and energy is inviolate, the distinguishable forms of matter and energy evolved from moment to moment.