Studies in Genesis 1
And God said, “Let there be an expanse in the midst of the waters, and let it separate the waters from the waters.” And God made the expanse and separated the waters that were under the expanse from the waters that were above the expanse. And it was so. And God called the expanse Heaven. (Genesis 1:6-7 ESV)
God uses one word four times in these verses. It is the word “expanse” or “firmament.” An “expanse” is a place separating one solid thing from another. During the time just after creation, God began to separate solid from solid and liquid from liquid putting a space between them. It would seem that as the universe expanded and grew chunks of matter move farther apart from each other until the distance between these chunks, from our perspective, was enormous.
Yet, in these verses God is talking about earth, what will become the habitable place upon which He created life. Here, He separated “waters from the waters” putting a space between them. It is this space which is an “expanse.” This “expanse” could be small, enveloping the earth, or large, containing the entirety of the heavens, all of space.
It would appear God created matter in at least three forms: solid, liquid and gaseous. Gas is differentiated from liquid, which is differentiated from solid, by the amount of space between each atom, or the expanse of space around each molecule. Those atoms and molecules tightly placed are more solid than those loosely held together.
An “expanse” is a defined space between the matter God created and molded into its various forms.