Chapter 21 Ray D'Inverno Scalar Optics, congruence of null geodesics

  • Thread starter portugal
  • Start date
  • #1
1
0
First of all this is my first thread, so I apologize for any mistake.
Perhaps this is a stupid question, but i need some help in exercise 21.10 of D'Inverno, to write down geodesic equation for l^a, which is a vector tangent to a congruence of null geodesics and then by a rescaling of l^a:

l^a -> A l^a how we conclude that l^a;b l^b=0 ?
 

Answers and Replies

  • #2
11
0
Hello, try to use general geodesic equation and then simplify the connection term with the definition of covariant derivative. Read about affine parameters.

I'll try to post a solution attempt. ( Ray D'inverno is a nice book has introduction to general relativity aspects).
 
Last edited:

Related Threads on Chapter 21 Ray D'Inverno Scalar Optics, congruence of null geodesics

Replies
4
Views
7K
  • Last Post
Replies
3
Views
931
  • Last Post
Replies
3
Views
2K
  • Last Post
Replies
1
Views
608
  • Last Post
Replies
7
Views
13K
Replies
0
Views
799
Replies
2
Views
2K
Replies
1
Views
1K
Replies
4
Views
351
  • Last Post
Replies
2
Views
1K
Top