Let’s begin with Borges’ metaphor of the cartographers who made more and more accurate maps of the world until their map became as big as the world it was mapping, and finally, identical with it.
We perceive the world by making a map or model of it. At each glance we receive only a tiny bit if information. We coordinate these many tiny bits to make a meaningful pattern which we are constantly adjusting. This is our internal map of the world which we build from sensory, cultural and linguistic information.
We each have a world inside our heads (WIOH) created in this way made of language, maps, stories, diagrams, metaphors, mathematics and heaven knows what.
The WIOH becomes more sophisticated as our culture and communication develop and it becomes a more and more reliable guide to the real world out there (RWOT). We can make accurate predictions about how the RWOT will behave. We can make cunning devices based on our sophisticated maps. But the RWOH must always be bigger and more comprehensive than the WIOH – which is only a map after all. The RWOT must contain the WIOH.
But what if our mapping and calculations became so sophisticated that they reveal a mathematical principal which transcends the RWOT, a principal which suggest that the RWOT is just a part of an even greater reality, which predicts the existence of other real worlds. Then our map becomes bigger than the real world. In an incredible feat of space-warping, like a hollow rubber ball suddenly flipping inside-out, the real world suddenly lies inside our heads.
This super-map is the territory of the theory of Multiverses. Will it prove to be a useful map or is it the equivalent of scribbling “Here be dragons”on unknown territory?