The Big Bang Theory explains the Beginning of the Universe as: In the beginning, Universe was just a Bubble which was so small, that it was smaller than the smallest Atom. “Suddenly”, the Bubble started to Expand rapidly and the Universe, as we see it now, started to Evolve (better – Expand). The Universe expanded from a High Density and a High Temperature State.
The Big Bang theory is considered to be one that Explains the Beginning of the Universe, but the THEORY fails to give a Clear Picture of the Beginning of the Universe. Why? See, the Theory begins by stating that in the beginning, the Universe was so dense and so small, and it was smaller than an Atom. But what about the Origin of that Bubble (or the Initial Universe)? The Bubble is considered as the Initial Universe. If it is so, then the Big Bang is not “literally” and “scientifically” the beginning of the Universe. The Big Bang Theory just explains how the so-called Initial form (BUBBLE) of the Universe evolved into the Current State. There should be an Explanation about the FORMATION OF THE INITIAL FORM OF THE UNIVERSE.
The Big Bang Theory claims to have explained the Beginning of the Universe and it is also widely accepted because it supports or explains various phenomenon in the Universe like the Cosmic Microwave Radiation and the Movement of Galaxies. But the theory has lost its PURPOSE, because it fails to Explain THE BEGINNING of the Universe.
Read about Time Travel