Realm of Transcendence
Have you ever wondered how an ant would visualize your pouring water on it or your destroying its anthill? Of course, as a human being it is difficult to comprehend its perception of such intrusions. Very likely, all that an ant perceives is only a disturbance that potentially endangers its life and it just tries to avoid it. It would not be able to comprehend your entire towering figure and your particular action. So pouring of water or destroying its anthill for an ant could simply be an equivalent of a rainfall or an earthquake for a human being.
The greater the disparities in the states of mind between two creatures, the greater will be the tendency to perceive an action by another living entity as a disturbance. A hierarchy in the states of mind can be proposed: the unicellular organisms at one end and the humans at the other extreme with other creatures in between. We can extrapolate this hierarchy beyond the human mind: What we see as an earthquake or hurricane could actually be an intrusion from another creature at a higher state of mind whom we cannot perceive, just as an ant cannot perceive us in our actions. This could likely be the reason in Hinduism, the natural forces like wind etc. have been given some anthropomorphic qualities. Ultimately, by this extension we reach a single God-head who is superior to everything and controls all.
Realm of Immanence
The simplest known independently living entity is a cell (or its organelles). A collection of these cells is called a tissue. An organ consists of a bunch of such tissues and a collection of organs makes up the organism. Each cell independently can live like an organism itself given the right environment. Hence, just as an organism has a sense of being an independent agency, within it, there are numerous “beings” likecells, tissues etc. that have their own sense of being an independent entity. As in the transcendental hierarchical realm, an entity can perceive the entities below it in their entirety, but not of those further up. Extrapolating this realm further, all creatures could be perceived as a small part of a bigger cosmic entity. Extending this ad infinitum, we reach a single all-pervading entity beyond which no other entity exists. This entity is referred to in Purusha Suktam as the “Being with thousand heads, thousand eyes etc.” as every other separate entity is part of that Being who pervades all.
Both these transcendental and immanent realms together show the existence of parallel universes. Religion has beautifully put forward the concept of life in a multiverse at a much more generic level than what science restricts itself to.