The Creator explicitly informs us that the sky is seven. For

understanding the first version of the sky, which defines the sky is the atmosphere, it is clear that the seven heavens are the seven atmospheric layers of the atmosphere. What about the seven great skies? This is still a great mystery to man. There is some understanding of this. Some understand that this great sky is also physically layered, as the sky is small.
There are also those who understand it not as a physical layer, but a dimensional layer as it is contained in the book Terendes in Sidratil Muntaha, by Agus Mustofa. If the first big sky we occupy is 3, then the 2nd, 3rd, 4th, and 4th is the dimensionless nature 4, 5, 6f.
The understanding of this version says that humans live in the sky dimension 3, the jinn live in the heavenly realm dimension 4, the soul of the laity lives in the heavenly realm dimension 5, the spirits of the aulia, martyrs, angels, and the prophets live in the celestial realm of higher dimensions his position.
When the events of isra miraj, the prophet met with several prophets in various layers of heaven. Prophet Muhammad met Abraham in the seventh heaven, met Moses in the sixth heaven. Also met the prophet Adam, the prophet Joseph in the layers of the other ceiling. (Agus Mustafa, Fascinated in Sidratil Muntaha).
The lower-dimensional sky dwellers can not see the higher-dimensional sky dwellers. But the higher-dimensional dwellers of the sky can see the inhabitants of a dimensionless sky can not see the genie but the jinn can see humans.