Then how many fucking dimensions are there?
I'm seeing one site mentioning 10,11 and 26.
there are quite a few different variations of string theory en vogue right now.
most of them use mathematical calculations to help support their hypothesis.
those mathematical calculations fail when using 4, 5, 7, 9, 13, 18, etc dimensions.
but all the math works when using 10, 11 or 26 dimensions. depending on which variation of string theory the person is trying to solve for, of course.
that's it. an unproven hypothesis works better when the math uses a specific number of dimensions. it certainly doesn't prove there are that many dimensions.
and outside of "math", no one is really sure what, exactly, a dimension is (other than the 4 we experience with our senses, that is).
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i don't mean to diminish science, string theory, etc. but it's all in it's infancy. one of the en vogue string theories may eventually become the best model to help us understand what's going on in our universe. but odds are it won't be any of them in their current form.
remember, the Big Bang only became a theory because Hubble (in the 20's or so) saw red shift everywhere, and folks simply extrapolated backwards. then in the 80's they found that the red shift is actually going faster further away - e.g. instead of shit slowing down from gravity as time goes on (like a bullet fired from a gun) shit moved away faster the further it got from other shit! and no one knows why!!! they can measure it, they can describe it's actions, but they have no fucking clue why. so they call it "dark matter" as a place holder and continue to study it. similarly, they can calculate quantum mechanics, but have no clue why it works the way it does.
we don't know a lot, and it's cool as hell.