Hell, I'm no theoretical physicist but I'm a BBC documentary junky and I've loved science since I was a kid.
Basically, we experience the universe in 4 dimensions - space + time. But in all their crazy physics mathematics the universe only made sense in 10 dimensions. But it still didn't really work when you tried to reconcile the macro physics of the Theory of Relativity etc and the micro of particle physics.
The dominant theory for a long time was called String Theory - rather than the little particle blobs we all learned about at school, the fabric of the universe is made of strings. It's almost impossible to get your head around in many ways, but there you are. Like strings of a violin they resonate at different frequencies, and just like musical strings produce different sounds, so the fundamental matter of the universe resonates and produces different properties which results in different elements.
But the problem with String Theory was that it couldn't account for the forces in the universe - gravity, electro magnetism and weak/strong nuclear force. Basically, gravity is an inconceivably weak compared to the other two forces in nature: how is it that a tiny fridge magnet can overcome the gravitational pull of the entire Earth and lift a pin off the table? And so M-Theory was born.
If you include an 11th dimension in the mathematics (the maths well and truly lost me at this point!) the strings become membranes. Membranes that nest within each other in the 11th dimension, like Russian dolls - never overlapping nor interfering with each other. And the theory goes that where electro magnetism and weak/strong nuclear force exist in our most salient 10 dimensions, gravity leaks across the 11th, permeating all and therefore losing its potency.
The implications of the 11th dimension is that it's possible to create an entire universe or reality, and that this will expand within our perceived reality and ultimately find its own nesting place in the 11th dimension. The documentary ended saying that scientists were in the process of attempting to do just that!
These realities would be entirely sealed from us once created. Like a Klein Bottle.
Quick digression (god you must be so bored by now!). How many sides does a piece of paper have? Two right? Well, maybe........but maybe not. You have to try this:
Take a thin strip of paper and curl it round to form a loop, like a link in a paper chain. Ok. So two sides right? The inside of the loop, and the outside. (ignoring the edges created by the thickness). So now separate the ends of the loop, make one twist and join them up again. And trace the surface of the paper with your finger... OMG. One side! Only one side!
This is the three dimensional equivalent of the two dimensional infinity symbol - a figure of eight. A never ending loop. In three dimensions this becomes a Mobius Strip (the strip of paper) - a two dimensional object in three dimensions. In four dimensions this becomes a Klein Bottle (see my picture). A completely enclosed, one sided, entirely self-referential space which you cannot enter nor leave because every point leads to every other point. (Now you see where I'm going with this...)
So say a bunch of pre-modern scientists, in Egyptians times for instance, found a way to create a universe which exists separately in the 11th dimension - maybe to have ultimate control over a reality, maybe to explore, maybe to escape, maybe by accident. This would be entirely enclosed like a Klein Bottle. SO they needed ways to get into and out of this space. But this space, being man-made, never fully disconnected from the membrane of our reality. There are places where they overlap, that people and objects have unwittingly stumbled upon and crossed over.....
And so subsequent generations began to explore and invent their own ways to enter this place.
But the objects and machines that they use, once placed into this entirely self-referential space outside of our reality and our particular mix of physical laws begin to behave differently - to become unpredictable, to expand and communicate. They begin to cause ripples in the membrane - maybe on purpose, maybe not - and sections begin to close in on themselves.....Klein Bottles within Klein Bottles, filling up with the flotsam and jetsam of all the generations that have gone before.
So here we are. Exploring a series of enclosed spaces within spaces. Accessible to us only through the portals - the method that our generation have devised of accessing the fractured reality created millenia ago - and any other tools/machines that are still operational from previous explorers.
This is my LONG but humble theory.
