Questions of Length, Distance, Direction, and Relativeness
Webster's New Twentieth Century dictionary defines the word dimension many ways. I use the definition below as a reference for two reasons, it's specific to Physics and it's consistent with the origin of the word.
dimension n. [OFr. dimension; L. dimensio, a measuring, from dimensus, pp. of dimetiri, to measure off; dis-, off, from, and metiri, to measure.]
7. In physics, a fundamental quantity, as mass, length, or time, in terms of which all other physical quantities, as those of area, velocity, power, etc. are measured;
The SI unit of Length is the Meter. The Meter is the basic unit of Length in the metric system, equal to 39.37 inches: it was meant to be and virtually is, one-ten-millionth part of the distance along a meridian from the equator to the pole. Today, it's still virtually equal to 39.37 inches but is more precisely defined as a specific number of wavelengths of radiation emitted from a particular element. A wavelength being the distance between corresponding points of two successive waves.
What does Length, as a "fundamental quantity," quantify? I would say that it quantifies whatever the Meter, or any other of its units of measurements, measures: the distance between two relative points of reference. Simply put, distance is quantified between things (length) and between the ends (length), sides (width), and/or tops and bottoms (heigth) of things. Is there a difference between (l), (w), and (h) other than relative direction?
Length is relative because the entire quantifying process is relative. All the units of measurement were derived from and are the distance's between two arbitrary and relative points of reference (even the length of the human foot is the distance between toe and heel), and any distance actually measured is dependent on first estabishing two relative points of reference in order to measure the distance between.
Is distance itself relative? If so,to what? Where does distance end?
