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Axes of a space-time diagram

  1. Oct 31, 2006 #1
    when we teach classical space time diagrams we measure on the vertical line the dependent space coordinate whereas on the horizontal axis we measure the independent time coordinate in accordance with what we learn say in analytic geometry.
    in special relativity we reverse the situation measuring on the horizontal axis the space coordinate and on the vertical one the time coordinate. That is a step not so easy to accept and a switch we should have always in mind. I understand that doing so we ilustrate the absolute character of absolute right and absolute left. are there other advantages as well?
    sine ira et studio
  2. jcsd
  3. Oct 31, 2006 #2


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    This is purely an aesthetic issue of course, you could draw the diagram either way...but if you have 2 spatial dimensions and 1 time dimension (as is done with most diagrams of 'light cones'), isn't it more intuitive to have the spatial dimensions as a horizontal plane (like the floor) rather than a vertical one (like a wall)? If you've read Abbot's "Flatland", do you picture it as horizontal or vertical?
  4. Oct 31, 2006 #3
    Thanks. I did not read the book you quote but the concept of dependent and independent physical quantity is so deeply rooted in my conscience that I would not perform any change.
    sine ira et studio
  5. Oct 31, 2006 #4
    The only real requirement regarding the stationary observer axes, are that the spatial axis and time axis are perpendicular. This is because time is assumed orthogonal to 3-space, and assumed to pass by steadily the same for those at rest with yourself.

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