Meaning of totally antisymmetric tensor

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Discussion Overview

The discussion revolves around the properties of totally antisymmetric and totally symmetric tensors, specifically focusing on the behavior of these tensors under the exchange of indices. The scope includes conceptual clarification and technical definitions related to tensor properties.

Discussion Character

  • Conceptual clarification
  • Technical explanation

Main Points Raised

  • Kevin questions whether a totally antisymmetric tensor changes sign under the exchange of any two indices and contrasts this with the behavior of a totally symmetric tensor.
  • Another participant asks for definitions of a tensor and specifically of totally antisymmetric and totally symmetric tensors, indicating a need for clarity on these concepts.
  • A reference to the Levi-Civita symbol is provided as an example related to the properties of antisymmetric tensors.
  • Kevin reflects on a misunderstanding stemming from a specific definition in Carroll's work, realizing that he incorrectly assumed a derivative of a tensor was totally symmetric, which led to confusion.

Areas of Agreement / Disagreement

The discussion includes some agreement on the properties of antisymmetric tensors as indicated by Kevin's realization, but there is no consensus on the definitions or implications of these properties, as participants are still clarifying their understanding.

Contextual Notes

There are unresolved definitions and assumptions regarding what constitutes a tensor and the specific properties of antisymmetry and symmetry in tensors. Kevin's earlier assumptions about the symmetry of the derivative of a tensor remain unaddressed.

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Simple question I am confused on. If I have a tensor M^{\alpha\beta\gamma} that is totally antisymmetric in its indices then is it the case that M changes sign under the exchange of any two indices? And as a followup, a totally symmetric tensor has no sign changes on any pair exchange of indices?

Thanks,

Kevin
 
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What is your definition of a tensor, and of a totally antisymmetric tensor (resp. totally symmetric tensor)?
 
Damn I think I figured out my problem. I was going off Carroll's definition/discussion of (anti-) symmetry (Spacetime and Geometry) which implies that an exchange of a pair of indices in a totally antisymmetric tensor yields a sign change. This is fine I realize now, what is not fine is the following.

I was looking at \partial_{\alpha}F_{\beta\gamma}. I know that \partial_{\[\alpha}F_{\beta\gamma\]}=0 and I then INCORRECTLY assumed that \partial_{\alpha}F_{\beta\gamma} was totally symmetric which was leading me into errors...argh...noob mistake.
 

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