Levi Civita 4 tensor as pseudotensor

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Homework Help Overview

The discussion revolves around the properties of the anti-symmetric 4-tensor, specifically the Levi Civita tensor, and its classification as a pseudotensor. Participants are exploring the implications of Lorentz transformations and the conditions under which the Levi Civita tensor could behave as a proper tensor.

Discussion Character

  • Exploratory, Conceptual clarification, Assumption checking

Approaches and Questions Raised

  • One participant attempts to demonstrate the transformation properties of the Levi Civita tensor under Lorentz transformations, questioning what is necessary for it to be classified as a pseudotensor. Another participant suggests the possibility of redefining the tensor in a way that could allow it to be treated as a proper tensor in certain metrics.

Discussion Status

The discussion includes attempts to clarify the nature of the Levi Civita tensor and its transformation properties. Some participants have proposed methods for redefining the tensor in curved space, indicating a productive exploration of the topic. However, there is no explicit consensus on the conclusions drawn.

Contextual Notes

Participants are considering the implications of different metrics and the role of the determinant in the classification of the Levi Civita tensor. There is an acknowledgment of the complexities involved in the definitions and transformations of tensors in various spaces.

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Homework Statement


Show that the anti-symmetric 4-tensor is a pseudotensor.


Homework Equations


[tex]\begin{eqnarray}<br /> x'^0 &=& \gamma x^0 - \beta \gamma x^1 \\<br /> x'^1 &=& \gamma x^1 - \beta \gamma x^0 \\<br /> x'^2 &=& x^2 \\<br /> x'^3 &=& x^3<br /> \end{eqnarray}[/tex]


The Attempt at a Solution


Under LT
[tex] e'^{ijkl}=\frac{\partial x'^i}{\partial x^q} \frac{\partial x'^j}{\partial x^r} \frac{\partial x'^k}{\partial x^s} \frac{\partial x'^l}{\partial x^t} e^{qrst}[/tex]
I got that
[tex]\begin{eqnarray}<br /> e'^{0123}&=&1 \\<br /> e'^{1023}&=& -1 \\<br /> e'^{0132}&=& -1 \\<br /> e'^{1032}&=& 1<br /> \end{eqnarray}[/tex]
After doing these first few terms, I'm seeing through induction that [itex]e'^{ijkl}=e^{qrst}[/itex]. Which is what we want for a tensor, right? A pseudotensor should depend on the determinate of [itex]e'^{ijkl}[/itex]. What am I missing??
 
Last edited:
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Nevermind, I solved it. Just wondering, could we make a metric where the Levi Civita 4 tensor is a proper tensor? I think this may be possible.
 
Hi! You can redefine the Levi-Civita in order to convert it a tensor. In curved space (including Minkowski space) you may define:

[tex]\epsilon_{\mu\nu\rho\sigma}=\left\{\begin{array}{c}<br /> 0~~\mbox{any two indices repeated}\\<br /> +1~~ \mbox{even permutation of indices}\\<br /> -1 ~~\mbox{odd permutation of indices},\\<br /> \end{array}\right.[/tex]

then define

[tex]\epsilon_{\mu\nu\rho\sigma}=g\epsilon^{\mu\nu\rho\sigma}[/tex]

where [itex]g[/itex] is the determinant of the metric you are using.

Then, define the usual standard tensor densities:

[tex]\tilde{\epsilon}_{\mu\nu\rho\sigma}=|g|^{1/2}\epsilon_{\mu\nu\rho\sigma}[/tex]

[tex]\tilde{\epsilon}^{\mu\nu\rho\sigma}=|g|^{-1/2}\epsilon^{\mu\nu\rho\sigma}[/tex]

and so, [itex]\tilde{\epsilon}[/itex] transforms like a tensor.
 
Last edited:
Yeah, I was thinking something just like what you posted, thanks for the verification.
 

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