>>12829061The other dimensions apart from the familiar three are small, relatively quantum, dimensions, so that everything is in the ground state relative to these dimensions, and you don't have to think of them as dimensions at all.
If you have a particle that can have a non-positional internal property which is a real number, like, say, temperature. Then you can plot the position and the temperature as a geometric 4 dimensional plot.
But when things are quantum, and energies are low, continuous possibilities reduce to a discrete set. The discrete freedom corresponding to motion in the extra dimension at our low energies is just the types of elementary particles we see. So the extra dimensions in string theory are not usefully pictured as actual spatial dimensions until an energy scale that is completely inaccessible, about 100 times larger than the Planck length.
So you don't need to think of them as dimensions at all, at least not when you are working at ordinary energies. Even at high energies, dimensions can swap for internal variables in string theory with no problem, since space is reconstructed from the oscillations of other things in the theory.
