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Paradox 1 of 2_23_17 v2
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Phil's working note, dated 2.23.17 (version 2), from his unresolved frames-document folders on the x'=Rx paradox. It contrasts a passive picture, where basis vectors are back-rotated by Rz(-α), with an active picture using Rz(α), and notes both cannot hold at once. It asks whether an equation like V'=Rz(α)V has any role under the passive view and argues it cannot be applied to the position vector. Some symbols were lost in text extraction.
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Paradox 1 of 2_23_17 v2. PhL 2.23.17
Consider these pictures
a Frame S b Frame S passive c Frame S active
(1) In picture b, "Frame S passive", the vector ' points southeast and we think e'i = Rz(-α)ei and we say that the basis vectors are "back-rotated". In particular, ' = Rz(-α) . This is the "passive view Picture". If you rotate year head to the right and look at b, you are in Frame S'. The Frame S components of the equation ' = Rz(-α) are ()'i = [Rz(-α)]ij()j.
(2) In picture c, "Frame S active", we write ' = Rz(α) as we would write for any vector V, and vector ' points northeast. This is the "active view Picture". Components are (')i = [Rz(α)]ij()j
All three drawings are in Frame S which we associate with our aligned piece of paper.
You obviously cannot have "both situations at once". In the first b situation ' in Frame S points southeast, while in the second c picture ' in Frame S points northeast.
So what do I say next? Here is one option
1. In frames doc, we want to take the passive view because: If we have a vector V in Frame S, we want to know: What are its V's components in Frame S'?
In the above example, if we have a vector in Frame S, we get its components in Frame S' using paragraph (1), not paragraph (2). Paragraph (1) says ()'i = [Rz(-α)]ij()j which gives the back-rotated vector components and this points to the southeast.
2. Question: Adopting this frames doc passive view,
(a) is there any role for the equation ' = Rz(α) ?
(b) is there any role for an equation V' = Rz(α)V ?
For item (b), we can certainly define V' = Rz(α)V as some new vector V' in Frame S.
But we cannot define ' = Rz(α) because ' is already defined as ' = Rz(-α).
We might define V' = Rz(α)V for some general vector V, but we cannot apply this to the position vector,. We cannot say r' = Rz(α)r because for r = we get the wrong answer.