The third heaven is the residence of God. The universe has expanded. This expanding universe continued for the first several days of the creation week, but sometime before day seven, it stopped expanding. The earth as somewhere near the center of the universe. The heavens and earth God created in Ge.
Creation week can thus unfold.
The deep contains all the mass of the visible universe. Gravity is functioning, and its great strength allows a clearly-defined interface to exist between the waters and the vacuum of the second heavens. Gravity causes it all to start to compress, it becomes very hot, and dense. Days Two and Three. God intervenes in the collapse and reverses the direction.