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3 space dimensions

  1. Jul 30, 2008 #1
    Is there any fundamental difference between the 3 dimensions of space that we experience. Such as the difference that we intuitively feel between the time and space dimensions
  2. jcsd
  3. Jul 31, 2008 #2


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    Usually in calculations we assume there isn't. For example, in physics the z-axis has a special meaning. Not because there is something physically significant about it, but on the contrary: we assume all spatial dimensions are equivalent and we can rotate our coordinate system in any way convenient to us. So we usually take it to be such that important vectors lie along the axis (e.g. a field along the z-axis, or a pendulum swinging in the x-y plane). If they weren't, we would not be able to do this.

    Of course, in "real life" we are usually in a gravitational field so we will have an intuitive sense of what is "up" and "down". So we have a sort of naturally aligned "z-axis". But the plane perpendicular to that is not fixed in that way. Otherwise, we wouldn't need stuff like compasses to agree on a non ambiguous way to describe directions (in fact I heard that there are certain people who always indicate directions relative to themselves, using "left" and "right" and who would probably find the idea of a fixed "north" direction ridiculous and incomprehensible).
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