I'm not sure it was mentioned before, but today I realized something new (new for me). Assume, M theory is right, so we have 10 spatial dimensions, and there can be a lot of 3-branes or higher n-branes floating in the 11 dimensional spacetime, so some multiverse theories may be possible. But one more thing, these spaces, or n-spaces are only work with only 10 axes, which are all perpendicular to each other. But, mathematically there is countable infinite number of geometrical axes, which are perpendicular to every other single axis, so these already multiverses, are just a set of 10 from the infinite number of perpendicular axes. Each "10-axis set" is an individual unit (lets call it this way). So, there is something interesting, if we think something like travelling to another multiverse. This multiverse can be in our unit, but it can be outside of our unit. So if we don't switch mathematically axes, just travelling to another 3-brane we will stay in our unit. If we switch our axes to some other axes which is presented in our unit, we will still stay in our unit. If we switch axes to some other, than the 10 of our unit, we will be in another unit. Maybe there is something common in all axes inside one unit among the perpendicularism, and the other interesting thing is, that if this is really the reality, then there is not only a few multiverses, or branes are "near" us (I mean like the distance of the curled up extra dimensions in our unit), but from the outside of our unit, there is infinite of them.
Another thing, I was wondering the exact cause of our limited visual abilities, why we can't really imagine anything, which is perpendicular to our space. Of course, dimension n+1 have almost infinite more information (even quantized), so I don't mean imaging a tesseract or anything. Simple, 4 axes which are perpendicular, or 3 axes, and only one point, to eliminate the previous information problem. I thought of the first thing, mentioned before, that there is infinite number of these "W" axes, which we need to imagine. Of course, we need only one to make the visualization, but I fail every time, no matter how much I degrade the 4-space. I see a possibility, that if someone can think, and visualize a 4-space (or a perpendicular axis to our 3 space), can visualize then any axis perpendicular to these, just by learning the method he used for the first one. I thought many things, it is phisically, or biological impossible for us, or it is ... mathematically?