I guess I should elaborate...
In his famous book, Earths Earliest Ages, G. H. Pember has made a scholarly and thorough study of this matter. Between Genesis 1:1 and 1:2 there was a period of time which he called the interval. No one can say how long this interval was. At any rate, it must have been a very long period of time.
After studying this matter thoroughly, Pember inferred that at a certain time after the original creation, Satan and his angels rebelled. Moreover, Pember inferred from the biblical record that in this pre-Adamic age there existed on the earth some living beings with spirits and that these beings also joined Satan in his rebellion against God. Thus, Satan, his fallen angels, and these living beings were all judged by God. After they were judged by God, these beings lost their bodies and became disembodied spirits. This is the reason that demons want to enter a physical body. It must have happened before the Adamic world, at the time God judged the heavens and the earth due to the rebellion of Satan and his followers.
Because of Gods judgment, the heavens did not shine, and the earth was covered by darkness. The fact that the earth, after being judged by God, was buried under the deep water proves that God must have judged the earth by flooding it with water. So, the earth became waste and empty, buried under deep water,
and covered with darkness (Gen. 1:2). Isaiah 45:18 tells us, God created the earth not a waste (Heb.). Job 38:4-7 shows that God created the earth in good order. It says that when God laid the foundations of the earth, laid the measures thereof, and stretched the line upon it, the morning stars sang together, and all the sons of God [the angels] shouted for joy. When God laid the foundations of the earth, He laid the measure upon it and stretched the line upon it. This means that He created it in good order. So, when the morning stars saw it, they were excited and sang, and when all the angels saw it, they shouted for joy.
When did this happen? It must have happened in Genesis 1:1, not in Genesis 1:2. How could the morning stars sing and the angels shout for joy when the earth became waste and empty? Whenever these two words waste and empty are used together in the Old Testament, they always denote a result of judgment. We see this in Jeremiah 4:23 (without form, and void should be waste and empty, Heb.), in Isaiah 24:1, and in Isaiah 34:11 (confusion should be a waste, Heb.). Whatever has been judged by God becomes waste and empty. The earth became waste and empty because it was judged by God. The darkness which was upon the surface of the deep was also a sign declaring that the universe of that age was judged, because darkness comes from Gods judgment (cf. Exo. 10:21-22; Rev. 16:10). Thus, the earth mentioned in Genesis 1:2 was not in the same condition as when created by God originally. It was created by God in a good order, but it became waste and empty.
This is known by many as the "Gap Theory." In my opinion it is not a theory. I believe it is absolutely biblical and it makes sense according to the original Hebrew and many passages in the Bible.
Tell me what you think.
