When light strikes either the rods or the cones of the retina, it's converted into an electric signal that is relayed to the brain via the optic nerve. The brain then translates the electrical signals into the images we see.
Recent experiments suggest that the brain plays an even more significant role than first thought in deciding what we see.
( Live Science website )
Through hypnosis you can convince any receptive subject of anything and they would experience it as real. Although, they can snap out of it if they feel threatened.
So this is what I am thinking ...
Why are we talking about Multiple Universes as if they all existed as real things. What we are talking about, surely, is Multiple Illusions / Projections of the mind.
By hypnotising two people you can put them in any circumstance of your choosing using suggestion and they will experience it. Can you suggest they be in two places ( illusions ) at once? One illusion seperated from the other person, and the second illusion in conversation the other person?
But come to think of it, that is no different to dreaming, is it?
Where you could be having a conversation with somebody and experiencing it as real - but, alone in bed also.
Consider erotic dreams, where men / women climax in their sleep.
All triggered by the mind, and mind alone.
Surely this represents a case where a person is in two places at once.
Because although our body is here in the "illusion" of sleep ( and having a physical reaction to stimulation ), the actual stimulation is occurring in a completely different illusion.
Am I making any sense?