People think that the theory of relativity is summed up in the equation E=MC2 . The truth is, relativity is an opportunistic rationalization of circumstantial evidence, and E=MC2 specifies a set of conditions which don't occur anywhere in nature.
God intends to bring about a permanent physical separation of light from darkness. Light weight and light bearing are synonyms, like dark and heavy are. In general heavier, denser materials are darker.
When God said, let light be, the sacrificial lamb was slain from the foundation of the world. That's why it went dark at the end of the first day, the second occurrence of darkness that we have to account for called night.
"Let light be, and light was" is normally translated as "let there be light, and there was light." We (that's me and the Holy spirit) develop the logic of how God caused light to appear.
The Bible accounts for the Big Bang nucleosynthesis. Popular science (SciPop) grudgingly arrived at this conclusion but it has no cause for it or source for the material used. The Bible gives us both.
Detection of the CMBR is taken to be support for the Big Bang Theory, although using the CMBR in this way only amounts to an inductive rationalization of circumstantial evidence to fit a premise.
Some people believe that Genesis 1:1 is a subheading which bookmarks the beginning of creation, not as a creative act. However, some people believe that it was a separate creative act.
The foundation of the world was an act of conception. Wisdom (Hydrogen, H+) fused with the Holy Spirit (alpha Oxygen, αO2-) to form the Hydroxyl ion (OH-). This existed with Wisdom (H+) to be the deep (H2O).
If wisdom was with God throughout the process of creation, then is this another aspect of Jesus Christ? Are we talking about Jesus/the Word/the deep/wisdom?
In pondering the physics of creation we have come to understand that the earth is part of the ongoing process of the permanent physical separation of light from darkness. The process is not complete. Yet.