Unitary coordinate transformation = rotation?

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SUMMARY

The discussion centers on the properties of unitary transformations represented by the matrix U. It is established that if U is unitary, defined by the condition U-1U = UU-1 = I, the transformation corresponds to a pure rotation, with volumes remaining invariant due to a Jacobian determinant of 1. The conversation clarifies that linear transformations do not include translations, but may involve reflections.

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Homework Statement


Suppose I define a linear coordinate transformation that I can describe with a matrix U.
If U is unitary. i.e.
[tex]U^{-1}U = UU^{-1}=1[/tex]
does that necessarily imply that the transformation corresponds to a pure rotation (plus maybe a translation), so that I may assume that volumes are invariant?


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The Attempt at a Solution

 
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Yes, volumes are invariant, certainly. The jacobian is 1. There are no translations if the transformation is linear. There could be reflections.
 
Thank you.
 

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