Hello everyone. This is my first post here, though I've stumbled upon the site on several occasions while investigating various physics concepts over the years. I've decided to post now because of a maddening dearth of information regarding the definition of each of the additional dimensions predicted in Superstring Theory. I realize this is a topic which has been opened here many times before, but it seems all those threads have long since died... mostly because no conclusions could be reached. So here we go again. Usually when this question comes up, the extent of the answer is that the additional dimensions are curled up at every point in our familiar spacetime into a compactified Calabi-Yau manifold. This is all well and good, and to this extent I understand it. My question is in regards to the specific identities of the extra degrees of freedom represented in this manifold. I know that this is sort of the central problem in string theory, but we should be able to talk about it in layman's language and understand something about it intuitively, don't you think? My understanding so far: Dimensions 1 - 4 represent our classical spacetime. They are defined in our experience by our relationship to Earth's surface. 1: Length (forward - backward, or longitude/latitude) 2: Breadth (left - right, or latitude/longitude) 3: Height (up - down, or altitude) 4: Time (past - future, or duration) So far so good. All this basically means that at our ordinary mundane scale, there are four meaningful values by which any point in our experience is defined: where it happens, in three dimensions, and when. It then follows that the additional dimensions should correspond to meaningful values. The four classical dimensions are large; probably infinite in extension. A moving object has momentum in spacetime. At relativistic speeds, a large portion of its ordinary fixed movement through time is converted through a Lorentz transformation into movement in a spatial dimension. But the additional dimensions are small, somewhere between the TeV scale and the Planck scale. As far as I understand it, objects (particles) can have momentum in these dimensions just as they have momentum in space. But since the dimensions are small, a particle moving in one of them will circumscribe the universe in that dimension. The higher the frequency of its vibration as it travels in that direction, the higher its energy. For instance, an electron's movement in one of these additional dimensions corresponds to its charge. Its movement in another corresponds to its magnetic polarization. Therefore, two of the additional dimensions correspond to meaningful values of the electromagnetic force. 5: electric charge 6: magnetic polarization Momentum can be translated readily between these two dimensions, and also out of them into our familiar four as photons moving in spacetime. The photon has no momentum in those two dimensions, and therefore no mass or charge. All its momentum is in spacetime. From here on my intuitive understanding gets a little fuzzy. Does the value of quantum spin correspond to momentum in a higher dimension? 7: spin (?) Dimensions higher than this will have much smaller diameters, between the 10^16 TeV scale and the planck length. Momentum in these dimensions can not be readily transfered into others, therefore the forces residing there are confined to their own scales, which is what we see in the real world. 8: weak gauge interactions 9: strong force 10: higgs field interaction (?) At the planck scale, rotation of 10D unit spacetime in any dimension should look identical, representing grand unification and perfect symmetry. Does this seem like a reasonable description to those of you who know more about these topics on the level of their actual experimental values? Is this a consistent layman's description of higher dimensional spacetime? Please respond with any corrections or criticisms of this model. Thank you.