Levi-Civita Symbol: Understanding Rank 8 Tensor Properties

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    Levi-civita Symbol
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Discussion Overview

The discussion revolves around the properties of the Levi-Civita symbol, specifically its classification as a pseudotensor and the implications of combining it with other tensors. Participants explore the conditions under which the product of Levi-Civita symbols results in a true tensor of rank 8, raising questions about the transformation properties of pseudotensors versus true tensors.

Discussion Character

  • Exploratory
  • Technical explanation
  • Debate/contested

Main Points Raised

  • One participant notes that the Levi-Civita symbol is classified as a pseudotensor because its components do not change sign when one or three coordinates change sign.
  • Another participant questions how the product of two Levi-Civita symbols, which are both pseudotensors, can result in a true tensor of rank 8, given that neither changes sign under certain coordinate transformations.
  • A participant explains that a pseudotensor includes the determinant of the Lorentz Transformation (LT) in its transformation properties, which introduces a sign change compared to true tensors.
  • There is a clarification about the meaning of "LT," with participants humorously suggesting alternative interpretations.

Areas of Agreement / Disagreement

Participants express uncertainty regarding the classification of the product of Levi-Civita symbols and the implications of their transformation properties. There is no consensus on the resolution of these questions.

Contextual Notes

Participants have not fully resolved the implications of combining pseudotensors and true tensors, nor have they clarified the mathematical steps leading to the conclusion about the rank 8 tensor.

Who May Find This Useful

This discussion may be of interest to those studying tensor calculus, particularly in the context of theoretical physics and relativity.

qinglong.1397
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I am reading Landau and Lifgarbagez's Classical Theory of Fields, 4th edition. In the beginning of page 18, the completely antisymmetric unit tensor is said to be a pseudotensor, because none of it components changes sign when we change the sign of one or three of the coordinates.

Then, in the 2nd paragraph, the product [tex]e^{iklm}e^{prst}[/tex] is a tensor of rank 8 and it is a true tensor! Why?

We know that [tex]e^{iklm}[/tex] does not change sign when one of the coordinates changes its sign. Either does [tex]e^{prst}[/tex]. Then the product does change its sign either. How could it be possible that the product is a true tensor?

I totally cannot understand. I need your help, your hints. Thank you!
 
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A pseudotensor has the determinant of the LT included in its transformation.
This gives a minus sign compare to the transformation of a true tensor.
If a pseudotensor is combined with another pseudotensor, the determinant is squared and always gives +1.
 
clem said:
A pseudotensor has the determinant of the LT included in its transformation.
This gives a minus sign compare to the transformation of a true tensor.
If a pseudotensor is combined with another pseudotensor, the determinant is squared and always gives +1.

What does LT stand for? Thank you!
 
Lorentz Transformation, or Leprous Tyrannosaurus. I think here the first one is ment.
 
haushofer said:
Lorentz Transformation, or Leprous Tyrannosaurus. I think here the first one is ment.

Should be the first one. Is the second one an English name?
 
qinglong.1397 said:
Should be the first one. Is the second one an English name?
He was joking. A leprous tyrannosaurus would be a tyrannosaurus with leprosy.
 
Fredrik said:
He was joking. A leprous tyrannosaurus would be a tyrannosaurus with leprosy.

Ha ha~~ That disease is scary...
 

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