I'll try outline my question in clear terms, articulating specific aspects that are its primary motivators. I'm just beginning in my exploration of physics as a student, but a persistent question that I've been grappling with is this - why does the universe manifest scale?
More precisely, what is scale, in physical terms? Is it an extension of dimension? To be clear, I recognize that there may be an explanation grounded in dimensionality; however, it seems to me that scale does not equate to dimension. In the case of our universe things are contained within a three-dimensional space (at least at the macro level), but scale implies "levels" of containment within the dimensional containment space.
The way I make sense of it is as being akin to the surface area of dimension, but is this accurate from the standpoint of physics? Has the phenomenon of scale been theoretically defined?
The most significant aspect of this for me, is why it is that physics would work "differently" at different scales. The fact that at the macro level we observe behaviors under the theoretical banner of GR/SR while at the micro level QM becomes the rule makes it seem as if scale has some sort of primacy that extends beyond space in the GR/SR sense, because it seems to be setting distinct contexts in which different physics occur. Has this been explained?
Forgive any naivety that may come across due to my inexperience with physics, and for any of the less than rigorous aspects of my questions. I'm sure certain aspects of my question are probably just due to my dearth of knowledge of physics, but I haven't been confronted with what seems like a clear answer to the essential question of just what scale is in the view of physics.
Thank you in advance for any answers and insight on this question!