Why Do Space-Time Diagrams Reverse Axes in Special Relativity?

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Discussion Overview

The discussion revolves around the representation of space-time diagrams in special relativity, specifically the reversal of axes compared to classical diagrams. Participants explore the implications of this reversal, its aesthetic aspects, and its conceptual significance in understanding space and time relationships.

Discussion Character

  • Conceptual clarification
  • Debate/contested

Main Points Raised

  • Some participants note that classical space-time diagrams typically have the time coordinate on the horizontal axis and the space coordinate on the vertical axis, while in special relativity, this is reversed.
  • One participant suggests that the reversal may illustrate the absolute nature of spatial directions, questioning if there are additional advantages to this representation.
  • Another participant argues that the orientation of spatial dimensions could be more intuitive when visualized as a horizontal plane, drawing a comparison to the depiction of dimensions in the book "Flatland."
  • Some participants express a strong attachment to traditional representations of dependent and independent variables, indicating resistance to changing the established conventions.
  • A later reply emphasizes that the only requirement for the axes is that they remain perpendicular, reflecting the assumption that time is orthogonal to space.

Areas of Agreement / Disagreement

Participants express differing views on the appropriateness and implications of reversing the axes in space-time diagrams. There is no consensus on whether this change is beneficial or merely aesthetic.

Contextual Notes

Participants highlight the dependence on traditional definitions of dependent and independent variables, as well as the potential for confusion arising from the reversal of axes in different contexts.

bernhard.rothenstein
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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
 
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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?
 
JesseM said:
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?
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
 
bernhard.rothenstein said:
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?

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.

pess
 

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