I’m increasingly of the opinion that string theory and the multi-dimensional universe(s)... is just a cop-out. It’s a kluge. It’s intellectual duct-tape, and it’s what happens when we simply don’t understand something very well at all.
I tend to think that the real answer, whatever it is, is simpler and more elegant.
Need Mr. Barclay and Einstein in the holodeck figuring this out, hee hee. (Saw recently a re-run of ST:TNG where what turned out to be aliens jacked up Barclay’s brain)
Well... If the Klein-bottle is the 2-dimensional version of the Mobius-Strip, then maybe the Universe is the 3-dimensional version of the Klein-bottle.
That would account for weird dimensionalities, wouldn’t it?
Yet, what has always given string, or M-Theory it´s strong appeal is that it mathematically unifies relativity and quantum theory as no other framework ever has. This alone is what holds so many in it´s...charm.