Space is potential field for matter's coming into being

Ether was this field, mistranslated.

Every esoteric tradition divides 'worlds' into three.

I the Eastern, the Desire Realm (kāma-loka), the Form Realm (rūpa-loka), and the Formless Realm (ārūpya-loka).

Others would have it: The “three realms of existence” as the realm of the five components, the realm of living beings, and the realm of the environment.

the earth (Bhuloka), heaven (Svarga), and hell (Naraka),

or the earth (Bhuloka), heaven (Svarga), and the netherworld (Patala)

The Brahmanda Purana conceives them to be Bhūta (past), Bhavya (future), and Bhavat (present).

In Christian tradition, it's the Trinity.

There are said to be 7 heavens to represent the 7 stages of evolution/involution (jacob's ladders/angels) of matter coming into being.

Ether was and still is the word.