It is equally valid to represent time as a circular number line with 24 equal length segments, or to represent time as a circular number line with 24 equidistant dividing points. The segments are exactly one hour in length, and the points are exactly one hour apart.
The term meridian connotes the point model. In the point model, half of the circle being ante meridian and half being post meridian leaves the question of to which half the point belongs. But this is not a question solely for the meridian point: for all points in the point model, to which hour do the points on the number line "belong"—the period before or the period after? It is simplest to say that the points begin an hour rather than end it, and thus noon earns the term P.M. since it is part of the entire 13th hour which is entirely post meridian.
This perhaps arbitrary decision harmonizes well with the equally valid segment model. Where does one locate the exact point in time which is halfway away from the very beginning of the first segment? It must be the very beginning of the thirteenth segment. If the whole 13th segment is labelled with the number 12 and is post meridian, then it is convenient, when using the number 12 exactly with no fraction for the beginning of the 13th segment, to call it post meridian as well.
Noon belongs to the noon hour. And midnight belongs to the midnight hour.
[COLOR=black #d0d0d0]My alarm clock causes time travel. When I hit snooze, no apparent time passes before the alarm sounds again, but the universe has in fact moved forward through time by ten minutes![/color]
![[thumbsup2]](/data/assets/smilies/thumbsup2.gif "[thumbsup2] [thumbsup2]")
