The deep had to be transformed in order to produce light. Formless became formed, empty became full, dark became light. However, this caused a new darkness: night. Not the absence of light, the obstruction of light.
God can't abide sin, he can't look on it. Yet in order for free will to be a possibility, sin has to be possible. How does a perfectly pure and righteous God create a world where evil exists? He became sin for us.
In the beginning the deep was formless. The subsequent account of creation shows how form and function go through several rounds of increasing order and complexity. The first was to take on the form of a sphere.
There are three things in Genesis 1:2, besides the the deep, which describe the state of the universe before God said "let light be." We (that's me and the Holy spirit) use this to deduce that it was a zero-G environment.