A Ricci tensor for Fermi normal coordinates

  • Thread starter Thread starter TimWilliams87
  • Start date Start date
Click For Summary
Fermi normal coordinates are discussed in the context of an inertial observer on a reference curve, with the metric expressed as g = eta + h, where eta is the Minkowski metric and h represents spacetime curvature perturbations. The metric components are detailed, showing how they relate to the Riemann tensor and its second derivatives. The discussion raises the question of whether components of the Ricci tensor can be expressed solely in terms of these second derivatives, specifically inquiring about the component R_{00}. The relationship R_{00} = g^{ii}R_{0i0i} is mentioned, though it is noted that this could lead to complexity. The conversation emphasizes the connection between the Ricci tensor and the metric's second derivatives.
TimWilliams87
Messages
7
Reaction score
0
TL;DR
Can the Ricci tensor be written simply in terms of second derivatives of the metric by the relation with the Riemann tensor?
I am learning about Fermi normal coordinates for an inertial observer on a reference curve from the textbook ''Advanced general relativity'' by Eric Poisson. The metric is written as g = eta + h, where eta is the Minkowski metric and h is the spacetime curvature perturbation close to the geodesic up to order x^2. t is proper time along the geodesic.

In these coordinates, the metric can be expressed as

$$ g_{tt} = -1 -R_{tatb}(t)x^ax^b + O(x^3), $$

$$ g_{ta} = \frac{2}{3}R_{tbac}(t) + O(x^3), $$

$$ g_{ab} = \delta_{ab} - \frac{1}{3}R_{acbd}(t)x^cx^d + O(x^3), $$

where ##R_{abcd}## is the Riemann tensor. It is stated in Poisson that these are related to statements regarding second derivatives of the metric (which I assume are just spatial derivatives only of the perturbing part of the metric h).

Since the components of the Riemann tensor can be written in terms of second derivatives of the metric, can one write components of the Ricci tensor simply in terms of second derivatives of the metric? So, for example, what is the component of the Ricci tensor R_{00}?

We do have as usual the relation

$$ R_{00} = g^{ii}R_{0i0i} , $$

but this seems like it would become complicated.
 
Last edited by a moderator:
Physics news on Phys.org
@TimWilliams87 please review the PF LaTeX Guide. LaTeX formulas here are delimited by double dollar signs, for equations standing alone, or double pound signs for inline LaTeX. I have used magic moderator powers to edit your OP accordingly.
 
Moderator's note: Spin-off from another thread due to topic change. In the second link referenced, there is a claim about a physical interpretation of frame field. Consider a family of observers whose worldlines fill a region of spacetime. Each of them carries a clock and a set of mutually orthogonal rulers. Each observer points in the (timelike) direction defined by its worldline's tangent at any given event along it. What about the rulers each of them carries ? My interpretation: each...

Similar threads

Replies
13
Views
2K
Replies
6
Views
1K
  • · Replies 10 ·
Replies
10
Views
2K
  • · Replies 7 ·
Replies
7
Views
2K
  • · Replies 1 ·
Replies
1
Views
2K
  • · Replies 10 ·
Replies
10
Views
2K
Replies
12
Views
2K
  • · Replies 2 ·
Replies
2
Views
2K
  • · Replies 8 ·
Replies
8
Views
2K
  • · Replies 7 ·
Replies
7
Views
533