Geometry of the Riemann, Ricci, and Weyl Tensors

In summary, the conversation discusses the geometrical differences between the Riemann, Ricci, and Weyl tensors and the role of the Ricci scalar. The Ricci tensor describes the change in volume of a n-dimensional object in curved space, while a vanishing Weyl tensor indicates conformal flatness. The conversation also mentions the need for clarification and references to explore these concepts further. One specific question is how a pure mathematician would interpret these tensors in the Riemannian setting and compare them to Lorentzian-signature interpretations.
  • #1
Airsteve0
83
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Hi, I was wondering if someone wouldn't mind breaking down the geometrical differences between the Riemann, Ricci, and Weyl tensor. My current understanding is that the Ricci tensor describes the change in volume of a n-dimensional object in curved space from flat Euclidean space and that if we have a vanishing Weyl tensor that the space is conformally flat. However, I have a feeling these are 'rough' understandings and would just like to have a more solid concept of them. Oh, and in addition to these 3 tensors, does the Ricci scalar describe something else altogether? Thanks for any clarification!
 
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  • #2
I am also interested in this question
...but haven't found satisfactory answers.

Here are some references which may be helpful:
http://arxiv.org/abs/gr-qc/0103044 ("The Meaning of Einstein's Equation" by John Baez)
http://www.springerlink.com/content/j534310782m58575/ ("Geometry in a manifold with projective structure" by J. Ehlers and A. Schild)
http://www.springerlink.com/content/g1v07h0353723765/ ("The geometry of free fall and light propagation" by Jürgen Ehlers, Felix A. E. Pirani and Alfred Schild)
http://www.springerlink.com/content/q334654473650828/ ("On the physical significance of the Riemann tensor" Felix Pirani)

One specific question is "How would a pure mathematician interpret these tensors in the Riemannian setting [in arbitrary dimensions]?" and how would they compare and contrast with the Lorentzian-signature interpretations.
 

Related to Geometry of the Riemann, Ricci, and Weyl Tensors

1. What is the significance of the Riemann tensor in geometry?

The Riemann tensor, also known as the curvature tensor, measures the curvature of a manifold at a specific point. It is a fundamental concept in geometry, as it allows us to understand the shape and structure of a space. In particular, the Riemann tensor is used in Einstein's theory of general relativity to describe the curvature of spacetime.

2. How is the Riemann tensor related to the Ricci tensor and the Weyl tensor?

The Riemann tensor can be decomposed into the Ricci tensor and the Weyl tensor. The Ricci tensor describes the local curvature of a space, while the Weyl tensor describes the non-local, or "purely gravitational", curvature. In other words, the Weyl tensor captures the effects of gravity that cannot be explained by the Ricci tensor alone.

3. What is the geometric interpretation of the Ricci tensor?

The Ricci tensor represents the contraction of the Riemann tensor, which can be interpreted geometrically as the average curvature of a space in a certain direction. In other words, the Ricci tensor tells us how the space is curved in a particular direction, whereas the Riemann tensor gives us the full curvature information in all directions.

4. How do these tensors relate to the concept of parallel transport?

Parallel transport is a fundamental concept in differential geometry, where a vector is transported along a curve while maintaining its direction. The Riemann tensor measures the difference between two parallel transported vectors, while the Ricci and Weyl tensors capture the effects of curvature on parallel transport. In particular, the Weyl tensor measures the deviation from Euclidean geometry due to the curvature of the space.

5. What are some applications of the Riemann, Ricci, and Weyl tensors?

These tensors are used in a wide range of fields, including physics, mathematics, and engineering. In physics, they are essential in Einstein's theory of general relativity, which describes the gravitational effects on spacetime. In mathematics, they are used in differential geometry to study the curvature of spaces. In engineering, they are applied in fields such as astrodynamics and aerospace engineering to accurately model the curvature of space and its effects on objects moving through it.

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