Ive changed the heading of what was the physics section, because, it appeared to have nothing much to do with physics! I made a new physics description, and put it at the top, but I think it generally covers what most people know of as distance. I deleted the "distinctions" of distance that had been written, that said things like "the distance formula is not true for curved surfaces", which cant be true, because the distance formula is part of the law of physics and is always true! they were true in a general sense, but i didnt see how they had any useful meaning.

if someone understands the special theory of reletivity better than i do, can they please give some information on how distance applies generally in physics.

ive been thinking that it might be overkill to seperate this topic into physics/geometry/maths, because distance is all of them at once, and it doesnt need to be explained over and over in slightly different senses.