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Paradox another attempt v1
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Draft notes by Phil dated 1.11.15, from an appendix on Euler angles in a mechanics document on rotating frames. Using bra-ket notation, he computes the change d en(Φ) of the moving frame S basis vectors as seen from fixed frame S'. He finds that primed and unprimed components of R appear to coincide, calling this a Catch 22. He then compares components taken in S' and S, which give different results, and drafts how to explain this to a critic.
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This is the Title PhL 1.11.15
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en(Φ) = R(Φ)e'n
|en(Φ)> = |R(Φ)e'n>
|en(Φ)> = R(Φ)|e'n> = |e'i><e'i|R(Φ)|e'n> = |e'i> [R(Φ)]'in = |e'i> [R(Φ)]in
|en(Φ+dΦ)> = R(Φ+dΦ)|e'n> = |e'i><e'i|R(Φ+dΦ)|e'n> = |e'i> [R(Φ+dΦ)]'in = |e'i> [R(Φ+dΦ)]in
|(den(Φ))S'> ≡ |en(Φ+dΦ)> - |en(Φ)>
= |e'i> [R(Φ+dΦ)]in - |e'i> [R(Φ)]in
= ( R(Φ+dΦ)]in - [R(Φ)]in ) |e'i>
Then
< e'j |(den(Φ))S'> = ( R(Φ+dΦ)]in - [R(Φ)]in ) < e'j |e'i>
= ( R(Φ+dΦ)]jn - [R(Φ)]jn )
= [(den(Φ))S']'j
So here suddenly I am getting this result
[(den(Φ))S']'j = R(Φ+dΦ)]jn - [R(Φ)]jn
where the matrices on the right are the unprimed matrices! The only facts I used above were
<e'i|R(Φ)|e'n> = <e'i|ej><ej| R(Φ)|ek><ek| e'n>
= R(Φ)ij R(Φ)jk R-1(Φ)kn = R(Φ)in
[R(Φ+dΦ)]'jk = <e'i|R(Φ+dΦ)|e'n> = <e'i|ej><ej| R(Φ+dΦ)|ek><ek| e'n>
= R(Φ)ij R(Φ+dΦ)jk R-1(Φ)kn = ????
This is the Catch 22! Now if you think of
Back up, show time dependence t on things better.
en(Φ(t)) = R(Φ(t))e'n
|en(Φ(t))> = |R(Φ(t))e'n>
1 = |e'i><e'i| = |ei(Φ(t))><ei(Φ(t))|
so you think of this completeness AT ANY TIME t. Then you get
|en(Φ(t))> = |R(Φ(t))e'n>
<e'm |en(Φ(t))> = <e'm |R(Φ(t))e'n> = <e'm |R(Φ(t))| e'n> = R'mn(Φ(t))
Then it follows that
<e'm |en(Φ(t)+dΦ)> = R'mn(Φ(t) + dΦ)
and maybe this fixes the Catch 22 !!
Try this without the clutter of showing t :
<e'm |en(Φ)> = R'mn(Φ)
<e'm |en(Φ+dΦ)> = R'mn(Φ+dΦ)
****************************************************************
Let's now try to present this to the Critic Listener. Consider that viewed from Frame S' the Frame S basis vectors are moving and so
en(Φ) = R(Φ)e'n
or
|en(Φ)> = |R(Φ)e'n> . (*)
Completeness can be written
1 = |e'i><e'i| in the fixed Frame S' basis
1 = |en(Φ)><en(Φ)| for any Φ in the moving Frame S basis
For example, at a slightly later time when Φ has changed to Φ+dΦ we get
1 = | en(Φ+dΦ) > < en(Φ+dΦ) |
Close (*) on the left with the non-moving <e'm | to get
<e'm | en(Φ)> = <e'm | R(Φ)e'n> = <e'm | R(Φ)| e'n> = [R(Φ)]'mn
Then at some slightly later time where Φ has changed to Φ+dΦ we can write
<e'm | en(Φ+dΦ)> = <e'm | R(Φ+dΦ)e'n> = <e'm | R(Φ+dΦ)| e'n> = [R(Φ+dΦ)]'mn
This all seems just fine. Now consider
[R(Φ)]'mn = <e'm | R(Φ)| e'n> = <e'm |ei(Φ)><ei(Φ)| R(Φ) |ej(Φ)><ej(Φ)|e'n>
= [R(Φ)]mi [R(Φ)]ij [R-1(Φ)]jn = [R(Φ)R(Φ)R-1(Φ)]mn = [R(Φ)]mn
At a later time we replace Φ by Φ+dΦ everywhere in the above line to get
[R(Φ+dΦ)]'mn = [R(Φ+dΦ)]mn
Therefore we have shown that
<e'm | en(Φ)> = [R(Φ)]'mn = [R(Φ)]mn
<e'm | en(Φ+dΦ)> = [R(Φ+dΦ)]'mn = [R(Φ+dΦ)]mn
Now consider
|(den(Φ))S'> ≡ |en(Φ+dΦ)> - |en(Φ)>
Close with <e'm | to get
<e'm |(den(Φ))S'> ≡ <e'm |en(Φ+dΦ)> - <e'm |en(Φ)>
= [R(Φ+dΦ)]mn - [R(Φ)]mn
This says that
[(den(Φ))S']'m = [R(Φ+dΦ)]mn - [R(Φ)]mn = (dR)mn
Even though we are taking a Frame S' component on the left, we end up with the Frame S standard rotation matrices on the right!
What happens if you instead take a Frame S component?
<em(Φ) |(den(Φ))S'> ≡ <em(Φ) |en(Φ+dΦ)> - <em(Φ) |en(Φ)>
= <em(Φ) |e'i><e'i|en(Φ+dΦ)> - <em(Φ) |e'i><e'i|en(Φ)>
= [R(Φ)]im [R(Φ+dΦ)]in - [R(Φ)]im [R(Φ)]in
= [R(Φ)]im { R(Φ+dΦ) - R(Φ) }in
= [R(Φ)]im {dR}in
So this is a different result !!!!!!!!!!!!!
= [R(Φ+dΦ)]mn - [R(Φ)]mn