Does Relativity Demystified Have an Error in Index Notation?

  • Thread starter Thread starter Ai52487963
  • Start date Start date
  • Tags Tags
    Gr Index
Click For Summary
SUMMARY

The forum discussion centers on a potential error in the index notation used in the book "Relativity Demystified" by McMahon. Participants analyze a 2-dimensional line element, ds^2=x^2dx+2dxdy-dy^2, and question the method of raising and lowering indices. Specifically, the confusion arises from the use of the raised metric for lowering the vector W, when the lower metric should be applied instead. This indicates a possible typo in the book's examples regarding the application of index notation.

PREREQUISITES
  • Understanding of index notation in tensor calculus
  • Familiarity with metric tensors and their roles in raising and lowering indices
  • Knowledge of 2-dimensional line elements in differential geometry
  • Basic concepts of general relativity as presented in "Relativity Demystified" by McMahon
NEXT STEPS
  • Review the errata for "Relativity Demystified" by McMahon
  • Study the application of metric tensors in raising and lowering indices
  • Explore additional resources on tensor calculus and index notation
  • Learn about common pitfalls in applying index notation in general relativity
USEFUL FOR

Students of physics, particularly those studying general relativity, educators teaching tensor calculus, and anyone seeking to clarify index notation in the context of differential geometry.

Ai52487963
Messages
111
Reaction score
0

Homework Statement


Consider a 2-dimensional line element: ds^2=x^2dx+2dxdy-dy^2

Raise and lower the indices of given vectors by finding the raised index metric, etc, blah blah

Homework Equations


V_a = (1,-1) and W^a = (0,1)

The Attempt at a Solution


Solution is given and I understand how to raise and lower indices, but I'm just wondering if my book has a massive exemplary typo. They raise V by multiplying it by the raised metric, which is fine. I get that. I don't get why they use the raised metric for lowering the W vector. Shouldn't you just use the lower metric given by the line element?
 
Physics news on Phys.org
That's right. The whole point of the index notation is you can immediately see what you have to do.
V^a = g^{ab} V_b, W_a = g_{ab}W^b

Which book is that? You can usually find an errata online.
 
clamtrox said:
That's right. The whole point of the index notation is you can immediately see what you have to do.
V^a = g^{ab} V_b, W_a = g_{ab}W^b

Which book is that? You can usually find an errata online.

It's Relativity Demystified by McMahon
 

Similar threads

  • · Replies 3 ·
Replies
3
Views
2K
  • · Replies 2 ·
Replies
2
Views
4K
  • · Replies 7 ·
Replies
7
Views
1K
  • · Replies 3 ·
Replies
3
Views
5K
  • · Replies 7 ·
Replies
7
Views
3K
  • · Replies 17 ·
Replies
17
Views
2K
  • · Replies 1 ·
Replies
1
Views
2K
  • · Replies 1 ·
Replies
1
Views
2K
  • · Replies 4 ·
Replies
4
Views
4K
  • · Replies 7 ·
Replies
7
Views
3K