What is invisible realm

This question emereged to me while reading about Shiva(that which is not) the realm of nothingness from which everything comes and goes etc

So when the magacians say there astral traveling, or going out of body, or go this there, manifesting from that world to this world , are they talk about shiva or astral world

Is astral world or spirit world etc different from nothingness ?

Are there entity and worlds in nothingness?

They have to be talking about a manifested part of the universe, not shiva, not the Tao, not the void.

There nothing in this realm of nothingness by definition. It’s what things manifest out of, as soon as they have been defined (and confined into that definition), they exist, so they are no longer pure potential aka shiva.