How the Big Bang Began?

I really, need not get into the details, but in simple terms, the big bang is what has created the universe we know today. A process that lasted for a millionth of a second. A process that involved a different atmosphere altogether.

For now, we know the following things about the atmosphere and properties of that time.
- Happened for a millionth of a second.
- Extremely hot conditions.
- Interaction of the first hydrogen molecules.

There have been many theories till date, the most famous ones are,
- The hydrogen molecule was the creation of God.
- It already existed, but we knew only when time started.
- It was the leftovers of the old universe.

All these theories might lead to the answer, but because we have not truly proved the existence of God, and we can still dig in the question of where the hydrogen molecule already existed, but how? So, we take in the theory of the hydrogen molecule existing as a leftover.

Anything that starts must end. Keeping that in mind, the previous universe must have died, and its left overs are hydrogen molecules, these molecules are so basic that they can not be destroyed easily. And it requires only the interaction of two of these molecules to create an entire universe.

There are many theories, such as big rip, big crunch, big freeze. But we must assume that the universe ended as a big crunch, only this will be able to lead us to the answer of how the big bang has happened.

Just as how the universe is expanding now, one day the universe would have expanded so much that, it would have reached it maximum, then the universe starts to reverse its process and starts to shrink, hence destroying everything that it has made leading to the very beginning again.

The destruction of the previous universe has led to only the existence of mere hydrogen molecules. And we keep waiting till there is an interaction between these molecules. All time has ended and the hydrogen molecules roam around. Time again starts once these molecules interact again, making us the universe.

How was the previous universe created? Was it an infinite process, but it must have started somewhere? We still do not have that much intelligence, but we will definitely try to find the answer.