Are "small" extra space-time dimensions represented correctly? This is my first post, I searched briefly but I apologize if this is a commonly covered topic! The following is written in the spirit of the "aether" -- that, being an overcomplication with no evidence. One of my biggest stumbling blocks so far in learning about various ‘modern physics’ topics is the premise of extra space-time dimensions. My background is in Mechanical Engineering with a concentration in Robotics; I understand mappings and I can see how physical state variables may be physical in nature but not dependent in the vector sense. i.e. a robot with a x,y,z position and roll,pitch,yaw headings – these are six physical dimensions in a configuration space that are ultimately still linearly independent. When I hear talk of necessary extra dimensions that are assumed to be space-time constituents, explanations sometimes talk of ‘tiny circles’ or ‘really small dimensions’ or ‘travelling across the universe and ending up where you started’, etc. I must be missing something, though, because in all of those explanations, you are only travelling in the previously defined x,y,z,t dimensions, albeit via strange or miniscule trajectories. This, to me, does not constitute independent dimensions. The issue here is not that the mathematics requires the extra dimensions, but are these dimensions explicitly defined in "physical" terms? Are there units of distance? Are these just layman explanations or is this the extent of the leading theories in physics?