: On another line of thought, our three dimensions are
: rather arbitrary. Each dimension is 90 degrees from
: the other two dimensions (keeping in mind that the
: dimensions are never-ending lines as opposed to rays
: traveling in one direction), which, as I said before,
: forms a cube. But what if you thought of each
: dimension as 45 degrees away from each other? or 30?
: or 14.645? Why is 90 so special? I can't think of any
: reason why 90 degree dimensions are any more likely
: than any other dimensions. If this is true, then we
: could be living in any number of dimensions, from 1
: (or maybe 0, though I don't think that works) to an
: infinite number. In that sense, we could easily be
: living in 4 or 5 dimensions.
Basically, the dimension of a space is the number of coordinates needed to determine every point in that space uniquely, and under a few other constraints like continuity (so that a small change in any coordinate produces a correspondingly small change in the position of the point thus produced). Ordinary space is 3-dimensional because there's no way to uniquely and continuously determine any point within it using only 1 or 2 coordinates, but there is a way to do it with 3. And if you use more than 3 coordinates, there's always a way to drop a few and just have 3 left which determine all points between them.
The details of the coordinate system don't really affect the dimension number. Mathematically, you could ignore the standard Cartesian (90-degree) coordinates and choose, say, spherical coordinates, where you measure a) distance from the origin, b) angle above the horizontal, and c) angle from directly ahead. You'll always need 3 coordinates, though.
So to answer your question: Yes, the 90-degree system is a little arbitrary (although there are major reasons to favor it as the "fundamental" one, having to do with conservation laws), but that system isn't actually the reason why we call space 3-dimensional.
: This explains why time cannot (except in certain
: instances) be "sped up" or "slowed
: down": because time doesn't exist. But what about
: those 'certain instances'? Specifically, what about
: the light speed effect, where the faster you go, the
: 'slower' you 'move through time' (I'm using that term
: even though I'm arguing time doesn't really exist for
: lack of a better way of describing this) relative to
: the rest of the Universe? For example, if a person
: traveled at almost the speed of life for ten years or
: so, on Earth or any other object moving at slower
: speeds more time would have passed, say, 50
: years(that's a random guess, but I don't think it's
: wildly off). How does that work?
: My guess (keep in mind I'm only a freshman in high
: school, so someone with more knowledge/experience with
: astrophysics and astronomy can help me out here) is
: that moving very quickly through space simply causes
: atoms to somehow "change" more slowly
: relatively to atoms moving at lesser speeds. This
: creates the effect of a person or thing aging more
: quickly than something else, without the actual
: existence of time, which we need to explain these
: effects.
Remember that the most basic principle of relativity is that (steadily) moving systems work just like stationary ones. You're not allowed to say that motion actually causes anything. :-)
The easiest way to look at it is as a matter of geometry. The object's behavior is the same no matter what *you're* doing, but you see it from different "angles" depending on how you're moving relative to it. From one "angle" it's not moving at all in space, but it's moving quite fast in time; from another, it's moving near light-speed in space but it's almost stopped in time. Your motion determines which "directions" look like space and which look like time.
The preceding was a really stupid explanation, and you can look back and mock it mercilessly once you've taken some courses in linear algebra and mechanics. :-) Einstein himself wrote some very accessible explanations of relativity; you might look into them. One's at
http://www.amazon.com/exec/obidos/ASIN/0517884410/qid=981097535/sr=2-3/ref=sc_b_3/102-6541414-0159369
--SiliconDream
