Anitsymmetric tensor/switching indices problem

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Homework Help Overview

The discussion revolves around the properties of an antisymmetric tensor, specifically in the context of switching indices and the implications of using the Minkowski metric. Participants are examining the validity of certain derivations and the assumptions underlying the behavior of tensor components.

Discussion Character

  • Conceptual clarification, Assumption checking, Mathematical reasoning

Approaches and Questions Raised

  • Participants are questioning the validity of derivations involving the antisymmetry of tensors when switching indices. There are inquiries about the correctness of steps taken in the derivation and whether additional steps are necessary. Some participants are also exploring the implications of the metric's symmetry on the tensor properties.

Discussion Status

The discussion is ongoing, with some participants offering guidance on the validity of the derivations presented. There are differing opinions on whether certain steps are correct, and participants are actively seeking clarification on specific aspects of the tensor properties and the metric involved.

Contextual Notes

There is a mention of the Minkowski metric and its assumed symmetry, which is central to the discussion. Participants are also reflecting on the potential need for additional reading or resources to better understand the topic.

wasia
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Let's say that some non-operator (having only numbers as it's components) tensor is antisymmetric:

[tex]\omega^{\sigma\nu}=-\omega^{\nu\sigma}[/tex]
and
[tex]\omega_{\sigma\nu}=-\omega_{\nu\sigma}[/tex],

however, I have read in the Srednicki book that it is incorrect to say that the same tensor with one index down and one up would be antisymmetric as well.

Could you please point out, where and what are the errors of the derivation? Should I read something before asking such questions? g here is the Minkowski metric:

[tex]\omega^{\nu}\,_{\sigma}=\omega^{\nu\beta}g_{\beta\sigma}=-\omega^{\beta\nu}g_{\beta\sigma}=-\omega_{\sigma}\,^{\nu}[/tex]

Thank you.
 
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wasia said:
Could you please point out, where and what are the errors of the derivation? Should I read something before asking such questions? g here is the Minkowski metric:

[tex]-\omega^{\beta\nu}g_{\beta\sigma}=-\omega_{\sigma}\,^{\nu}[/tex]

Shouldn't there be another step in between?
 
wasia said:
Could you please point out, where and what are the errors of the derivation? Should I read something before asking such questions? g here is the Minkowski metric:

[tex]\omega^{\nu}\,_{\sigma}=\omega^{\nu\beta}g_{\beta\sigma}=-\omega^{\beta\nu}g_{\beta\sigma}=-\omega_{\sigma}\,^{\nu}[/tex]

This should be fine. Notice that you switched which index was up and which was down.
 
xboy, the steps in between might be something like
[tex]-\omega^{\beta\nu}g_{\beta\sigma}=-\omega^{\beta\nu}g_{\sigma\beta}=-g_{\sigma\beta}\omega^{\beta\nu}=-\omega_\sigma\,^\nu[/tex]
I assume they are valid, as g is undoubtly symmetric (at least in my case) and also g commutes with omega, as they contain only numbers.

Ben Niehoff, I do have noticed, that positions have changed.

However, if anyone could point out a mistake, or tell if that's correct, as Ben says, please do it.
 
Last edited:
Walia, your derivation seems correct to me. I can't think of a case of your derivation being invalid except for the metric being non-symmetric. But I don't know if the metric can be non-symmetric at all.
 

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