Are 3-vectors Defined by Their Transformation Properties?

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Discussion Overview

The discussion revolves around the definition of 3-vectors in relation to their transformation properties under different types of transformations, specifically rotations and Galilean transformations. Participants explore the implications of these definitions in the context of nonrelativistic kinematics and the potential formulation of nonrelativistic 4-vectors.

Discussion Character

  • Debate/contested

Main Points Raised

  • Some participants question whether 3-vectors are defined by their transformation properties with respect to rotations or Galilean transformations, citing examples like kinetic energy.
  • One participant asserts that Galilean transformations pertain to spacetime rather than just space, suggesting that vectors can be defined by their transformation properties under rotations and reflections.
  • A participant proposes the idea of formulating nonrelativistic kinematics using nonrelativistic 4-vectors, questioning if this can be achieved by taking the limit of Lorentz transformations as the speed of light approaches infinity.
  • Another participant confirms that Lorentz transformations reduce to Galilean transformations in the limit where the speed of light is considered infinite.

Areas of Agreement / Disagreement

The discussion contains multiple competing views regarding the definition of 3-vectors and their transformation properties, and it remains unresolved whether a consensus can be reached on the formulation of nonrelativistic kinematics in terms of 4-vectors.

Contextual Notes

Participants express uncertainty about the implications of defining vectors in relation to different transformation properties, and there are unresolved aspects regarding the definitions and limits involved in the transformation processes.

Heirot
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Are the usual 3-vectors defined by their transformation properties wrt rotations or Galileian transformations? E.g. kinetic energy would be a scalar wrt rotations but not wrt Galileian transformations.

Thanks!
 
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Galilean tranformations are transformations of spacetime, not space. Vectors in space can be defined by their transformation properties wrt rotations and reflections. Free vectors which can start at any point can be defined wrt isometries of space, i.e. rotations + displacements.
 
Oh, I see. Could it be possible to formulate nonrelativistic kinematics in terms of nonrelativistic 4-vectors? E.g. just put c->infinity in Lorentz transformations?
 
Yes, the Lorentz transformations become Galilean transformations in the limit c → ∞.
 
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