My current understanding of the variations of string theory includes the sentence "string theory needs (at least) 6 extra spatial dimensions to work, but because our observable universe consists of 3 spatial ones, we could assume they're very tiny".
Now, when we deal with our ordinary 4 dimensions, we don't consider them as finite, you're not gonna run out of space as you move forward in space. (I know this could be paradoxical if the universe actually has an edge, but we don't know that.) So how do we assign length to those "extra" dimensions? I know objects have lengths in their dimensions, but does the fabric of spacetime itself have it? Is this consistent with Einstein's theory of relativity?
one more question popped into my head, sorry
About considering them as tiny, couldn't they be just as infinite as the other three but because everything currently known to us is at most 3D we have no idea of what could be going on in other spatial dimensions? Or are we somehow sure that there exists no more of them?
Ok sorry this is the last one
To the extent of our knowledge, could the universe contain more dimensions that have very little to do with space or time? If yes, do we still have to consider those extra dimensions as spatial?