Understanding Tensor Components: The Role of Index Order in Vector Spaces

  • Context: Graduate 
  • Thread starter Thread starter quasar987
  • Start date Start date
  • Tags Tags
    Difference
Click For Summary

Discussion Overview

The discussion revolves around the role of index order in tensor components within vector spaces, specifically addressing the implications of index placement on the action of tensors. The scope includes theoretical aspects of tensor analysis and the relationships between vector spaces and their duals.

Discussion Character

  • Exploratory, Technical explanation, Conceptual clarification

Main Points Raised

  • One participant describes the representation of a tensor in terms of its components and the bases of vector spaces, highlighting the significance of index order in determining the action of the tensor.
  • The same participant questions whether the order of indices in the components of a function from one vector space to another carries meaning or if the indices could be interchanged without loss of information.
  • Several participants suggest references to literature, such as Geroch's and Nakayama's works, as potential resources for further understanding of the topic.
  • Another participant mentions Frankel's work in relation to the discussion, indicating that it may also provide relevant insights.

Areas of Agreement / Disagreement

There is no consensus on the question posed regarding the interchangeability of indices in the components of the function. Participants agree on the value of referenced texts but do not resolve the initial inquiry.

Contextual Notes

The discussion does not clarify the assumptions regarding the definitions of tensor components or the implications of index order, leaving these aspects open to interpretation.

Who May Find This Useful

Readers interested in tensor analysis, vector spaces, and the mathematical foundations of physics may find this discussion relevant.

quasar987
Science Advisor
Homework Helper
Gold Member
Messages
4,796
Reaction score
32
Say V is a vector space with base {e_i}, V* is it's dual with dual basis {e^i}. If someone says that T^i_{ \ j} are the components of a tensor, then I know this means that the actual tensor is

\mathbf{T}=T^i_{ \ j}e_i\otimes e^j

The order of the indices of the components of T indicates on which set is T acting. In this case, V* x V. Were the components T_j^{ \ i}, T would have acted on V x V*.

Now my question.

If \Gamma is a function from vector spaces V to W of respective bases {e_i} and {\tilde{e}_i}, and if we define the components of \Gamma as the numbers \Gamma_i^{ \ j} such that

\Gamma(e_i)=\Gamma_i^{ \ j}\tilde{e}_j[/itex],<br /> <br /> is there a meaning to the order of the indiced, or could I have just as well noted the coefficients as \Gamma^{j}_{ \ i}?<br /> <br /> Thanks.
 
Last edited:
Physics news on Phys.org
Hi, quasar987, have you looked at Geroch, Geometry of Physics or Nakayama, Geometry, Topology and Physics? These should answer your questions.
 
Chris Hillman said:
Hi, quasar987, have you looked at Geroch, Geometry of Physics ...

Frankel? :smile:
 
George Jones said:
Frankel? :smile:

Presumably, although Geroch's Mathematical Physics, if I recall correctly, also discusses this.
 
Chris Hillman said:
Hi, quasar987, have you looked at Geroch, Geometry of Physics or Nakayama, Geometry, Topology and Physics? These should answer your questions.

Nakahara, maybe ? :rolleyes:

Daniel.
 

Similar threads

  • · Replies 3 ·
Replies
3
Views
7K
  • · Replies 58 ·
2
Replies
58
Views
6K
  • · Replies 4 ·
Replies
4
Views
2K
  • · Replies 3 ·
Replies
3
Views
4K
  • · Replies 7 ·
Replies
7
Views
3K
  • · Replies 16 ·
Replies
16
Views
6K
  • · Replies 5 ·
Replies
5
Views
2K
  • · Replies 1 ·
Replies
1
Views
5K
  • · Replies 21 ·
Replies
21
Views
4K
  • · Replies 2 ·
Replies
2
Views
2K