Christoffel Symbols: Solving GR Homework | Fred

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Homework Help Overview

The discussion revolves around calculating the Christoffel symbols in the context of General Relativity, specifically using cylindrical coordinates. The original poster, Fred, presents a metric and seeks assistance in proceeding with the calculations.

Discussion Character

  • Exploratory, Assumption checking, Mathematical reasoning

Approaches and Questions Raised

  • Fred attempts to derive the Christoffel symbols from the metric he has found, but expresses uncertainty about the process. Other participants question the clarity and correctness of the metric presented, particularly regarding its derivation and notation.

Discussion Status

The discussion is ongoing, with participants seeking clarification on the metric and its implications for calculating the Christoffel symbols. Some guidance has been offered regarding the relationship between the metric and the inverse metric, but no consensus has been reached on the correctness of Fred's initial metric.

Contextual Notes

There is a noted confusion regarding the metric's formulation, and Fred acknowledges a mistake in his initial post. The discussion reflects a need for clearer communication of the mathematical steps involved in the calculations.

n1mrod
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Hey Guys,

I'm new here on the forum, and I hope someone can help me out.
I'm solving one of my GR homework exercises and I'm asked to find the christoffel symbols corresponding to cylindrical coordinates.
I'll post my work and please correct if you see mistakes.
I found the metric to be dR^2 + (R^2)(dtheta^2) + dZ^2
therefore
Gab=
1 0 0
0 R^-2 0
0 0 1

Can somebody kind of explain to me how to proceed with these calculations?

Thanks a lot!
Fred.
 
Last edited:
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You'll have to explain how you got that strange result before anyone can help. Where did the e come from?
 
Dick said:
You'll have to explain how you got that strange result before anyone can help. Where did the e come from?

Hey I'm sorry, I was writing the topic and the second part I copied from my other homework assignment, sorry I'm going to fix that.

Until the "matrix" Gab is what I did, but I'm not very sure how to calculate the christoffel from there, can you help me?
 
You calculate the christoffel by evaluating a summation of partial derivatives of the metric times the inverse metric. Again, you are not giving us much to go on.
 
Okay, but I put the metric I found. As you said, to calculate the symbols it's only necessary the Metric and the inverse metric, the inverse metric is calculated straight from the metric right? So I believe we have everything that is needed, but please correct me if I'm wrong.
Thanks.
 
I think so. If you are going wrong, you haven't done so yet.
 

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