Physics for Everyone: Dimension
One of the interesting things about humans and the physical world around us, is that, despite the fact that we live in it, and move around in it, our intuitive grasp of how it works sometimes (actually more frequently than we’d like) fails. Compounded with misleading (or no) education in the sciences, and many people misunderstand many aspects of physical interactions.
One of the most basic concepts in physics is Dimension (not normally capitalized, but I’ll do so for the purposes of this article for emphasis). However, it seems the majority of people who are neither physicists nor mathematicians seem to have a gross misunderstanding of what precisely Dimension is. Part of the fault of this can be laid at the feet of science fiction, where the term is heavily abused, and in fact misused when the author really meant something more along the lines of “alternate reality” or “parallel universe.”
A Dimension is NOT a universe, it is NOT a reality, it is NOT a timeline (well, not exactly on the latter, and I’ll get into that in a bit). Quite to the contrary, universes and realities are made UP of dimensions. Ours, depending upon with which theory group you are currently working, consists of either 5, 10, 11, or as many as 26 Dimensions.
What IS a Dimension? To put it most succinctly, a Dimension can be thought of as a direction in which one can measure something. It is a singularly definable aspect of something. When we’re using it to define the physical world, we usually will consider the basic Dimensions to be length, width, depth, and time – the four with which everyone is most familiar, and most people actually have some intuitive grasp.
Given the definition I just posited, one might wonder “in what other direction can one measure something beyond those basic 4?” Well, when you start delving into the deeper aspects of the physical universe, especially at the very very tiny levels, the quantum levels where things start getting interesting, and fields start doing fun things, one quickly discovers those 4 might not be adequate. And then when one further discovers that it might be possible to think of particles as vibrating strings, the basic 4 Dimensions prove WOEFULLY inadequate.
In String Theory, a Dimension, or the direction in which something can be measured, tends to lie in the ways in which a string can vibrate. And it turns out they can vibrate in a LOT of different ways (upwards of 26, to be precise).
So, to sum up, really, a Dimension, rather than being a universe in and of itself, is the most basic aspect of the universe, the most basic way in which a component can be measured. And it is the measurements of objects along those Dimensions, and movement throughout them, that makes things happen.