All form, and thus all realities (or ‘realms’) within the Creation are made of the same primal substance, known as ether, which exists within a container of space known as Akasha..
Akasha is consciousness itself seen as a primal clay, the starstuff from which all Worlds, from which all realities are made. It is the canvas, the elemental principle that gives birth to all other elements and their endless movement through the spacetime of it’s substance. In the mixture of these five elements, that of Earth, Air, Fire, Water, and Ether (spacetime/ether/embodied awareness) one experiences all the conditions of material existence. It is most subtle level of form before it dissolves back into the formlessness from whence it came, the initial place where the infinite intelligence of the Divine pours through into being. It is form itself. The substance of which the awareness is aware.
Akasha has an aspect that is transcendent of the other four elements. It is the base element from which the other four emerge. Eventually, after an infinity of changes, the base elements of Earth, Air, Water and Fire dissolve back into the Akasha from which they were made. Akasha is a meta-substance, that exists in the event horizon between form and formlessness itself.
Akasha is the context in which the phenomena known as ‘space’ and ‘time’ occurs, containing within it’s substance ALL potential events that have happened, are happening, or will ever happen in the Worlds of form.