Dear Physics enthusiasts, I'm just a curious guy, I don't have any fancy credential, and in fact I don't have formal education at all (for 'legal' purposes I'm just "literate"). I'm being honest about that right away so if that's a problem (what seems to be the case for a lot of scientists/scholars) you can just ignore this humble topic without further wasting your time. I must also say that English isn't my native language therefore some terms may be incorrect. I understand the mathematical concept of a dimension, and I also understand that the use of coordinate systems for physical purposes is just a representation of the reality, 3 dimensions is the absolute minimal quantity of information necessary to represent a volume, in this case in an Euclidean space 3 coordinates would be a point (while obviously 3 numbers could represent a vector, I'm being specific and making assumptions for simplicity, so let's not discuss semantics/concepts please). Everything makes perfect sense so far. For simplification, in analogical examples we tend to drop one axis in our coordinate system, the "flatlanders" explanation on how 3D objects would look on a 2D plane in my opinion is a decent example as long as you keep in mind all the time that it's just that, a representation, an exemplification just like the light cone generally is shown in a 2D space. The mathematics work perfectly, but I can't imagine a physical world like that, especially if it exists within a "3D" world, the first question that come to my mind, from a purely theoretic view is where would the plane/axis be aligned to in this 3D space? Would the 2D space within the 3D space even look like a "plane" (flat surface)? I mean, in any decent coordinate system the axis orientations don't matter: you can have two distinct 'origins' for two separate representations of the space using the same coordinate system, with unaligned axis, and you would be able to convert back and forth a coordinate (point) between these two representations you're using, the maths would work on any of them, that emphasizes the fact that they're just representations of the reality. Another question is on the practical side of things. You have 3 coordinates because things in real world they occupy a 'volume' in space, would these hypothetical objects in 2D spaces have no volume, or would the objects in the 2D space have a volume that's only observable from a 3D world that contains the 2D space? Those are just some 'philosophical' questions that shows me how the whole 2D exemplification of space is only useful when you don't think of it in literal terms, but always as an exemplification for something that's already a pretty rough approximation of nature. I don't understand extra spatial dimensions because of (among other things) the mathematical implications that emerge from that. Say you have one dimension, a 'line', it's quantisized in integers and is finite, say, from >0 to 10 (for simplicity), so you have a line like a ruler and you can mark 10 positions on it. Now imagine one extra axis, same rules, you now have X and Y and you can mark 10*10 positions. I observe here that every new dimension I add implies that all possible positions are exponentiated to the number of dimensions, in other words it's the same as having 10 lines stacked now, another dimension you have 10³, that means to me that the state of all previously added dimensions is multiplied by 10 every time you add a new dimension, in other words, say at this point you have 'nothing' in this 3D space/volume you're representing, if you add a 4th dimension, you now have 10 of these 'empty 3D spaces/volumes'. That could represent for example a space of 10x10x10 meters during 10 seconds. If you take multiple 'snapshots' of our current universe at different times, you exist in each one of them, in other words, you are 'duplicated' (not exactly) in each one of these snapshots, the information about you is 'repeated' in each of them. I can perfectly understand objects existing in four dimensions, when I see a "hypercube" I generally think of an object in a 'snapshot' of time that comprises a time 'interval', not a single point in time, for example on some images you can clearly picture a cube translating or scaling 'over time', but time is pictured in a single frame what appears like a time interval that is 'frozen', something like superposing pictures at different times, or a kind of 'motion' blur if you will, I can perfectly understand that, for example this image: https://en.wikipedia.org/wiki/File:Dimension_levels.svg Represents to me a cube translating over time. And I can understand the math behind this representation: https://en.wikipedia.org/wiki/File:8-cell.gif of a "4D" cube rotating, but I don't see how that's not totally arbitrary and invalid. I mean, rotation in this example ultimately means changing the coordinates of each 'point' of the object, in case of a cube, if you could rotate a 2D square in a 3D space, the square projection on the 2D space wouldn't keep the same 'area', but the square would have to exist in the 3D space because you can't figure out each points 'height' simply from the projection in the 2D plane, and I see that's the same concept, but apparently the same manifestation won't occur perfectly in this case (as volume), and again, I fail to see how that's not completely arbitrary. I can understand how we could go with extra dimensions. Applying the few concepts I can grasp of physics and math I can say that an extra dimension (beyond time), could very well look like the so-called multiverse. So to represent an event you would need its spatial and temporal location, and its "multiversial" coordinate(s). Everything works beautifully in my mind when I think like that, what really can't make sense of is thinking about 4 spatial dimensions plus time. I mean, time is the 4th 'spatial' dimension to a sense isn't it? I guess that's pretty much common sense in physics these days. I'm reading about things like some new unified physical theory proposals and I just can't get a good grasp because each one of them is about multidimensional spatial objects manifesting in our ordinary 'spatial volumetric' universe and I simply can't fathom things like that such as shape shifting objects manifestations and such. So if anybody could explain to me in layman's terms how to go about wrapping your head on the basic concept of that, I would really appreciate. It's not that I'm going to use that knowledge somehow because I'm just an uneducated and by comparison here a possibly quite dumb guy, but I'd really like to know more about what the prodigious minds are thinking of in order to better understand the beauty of our universe, even if only to examine the possible candidates and have an 'intuitive' opinion on them (since the theories are too complex). Does having an extra spatial dimension not imply another exponential number in this case? I mean, that all the other 3 dimensions they have to exist again for each state of this extra dimension just like the example above? If that's so, in this case the mathematical concepts I know won't work very well for this 'reality' (at least for understanding) and I wonder if there's something that represents the universe better than them. Thank you very much.