Derivation of the value of christoffel symbol

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Discussion Overview

The discussion centers on the derivation of the Christoffel symbols in terms of the metric tensor within the context of general relativity. Participants seek clarification on the definition and calculation of these symbols, exploring both theoretical and practical aspects.

Discussion Character

  • Technical explanation
  • Conceptual clarification
  • Debate/contested

Main Points Raised

  • One participant expresses a desire to understand how to derive the Christoffel symbols from the metric tensor and seeks clarification on their definition.
  • Another participant provides a link to a Wikipedia article, suggesting it may contain helpful information.
  • A participant mentions that the Christoffel symbols can be expressed as a function of the metric tensor through index permutation and resumming, but acknowledges difficulty in understanding this process.
  • Multiple participants provide the formula for the Christoffel symbols, indicating that while the calculation is straightforward, it can become tedious.
  • There is a discussion regarding the notation used, specifically the meaning of the partial derivative and the summation convention over repeated indices.
  • One participant corrects another regarding the limits of summation, clarifying that it should extend from 0 to 3, not 0 to 4, reflecting the four dimensions of spacetime.

Areas of Agreement / Disagreement

Participants generally agree on the formula for the Christoffel symbols and the notation used, but there is a correction regarding the limits of summation. The understanding of the derivation process remains unclear for some, indicating a lack of consensus on that aspect.

Contextual Notes

Some participants express uncertainty about the process of permuting indices and resumming, highlighting a need for further clarification on these mathematical steps.

Boltzmann2012
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Hi,
I am new to general relativity and as I would like to find out how we could derive the value of christoffel symbol in terms of the metric tensor.
I have also heard that it was given as a definition for the christoffel symbol and would like a clarification on that.

Regards
Bltzmn2012
 
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By permuting the indices, and resumming, one can solve explicitly for the Christoffel symbols as a function of the metric tensor:

I didnt quite get that(although I was given the formula underneath).could you please explain what is permuting the indices. I am really new to this stuff.

Regards
Bltzmnn2012
 
[tex]\Gamma^\rho_{~\mu \nu}=\frac{1}{2} g^{\rho \lambda} (\partial_\mu g_{\nu \lambda}+\partial_\nu g_{\mu \lambda}-\partial_\lambda g_{\mu \nu})[/tex]

It's relatively straightforward to calculate the components of the Christoffel symbols from the components of the metric. It can get pretty tedious though.
 
Last edited:
elfmotat said:
[tex]\Gamma^\rho_{~\mu \nu}=\frac{1}{2} g^{\rho \lambda} (\partial_\mu g_{\nu \lambda}+\partial_\nu g_{\mu \lambda}-\partial_\lambda g_{\mu \nu})[/tex]

It's relatively straightforward to calculate the components of the Christoffel symbols from the components of the metric. It can get pretty tedious though.

Yes - a few comments on notation for the OP
[tex]\partial_\mu = \frac{\partial}{\partial_\mu}[/tex]

Summation over lambda is implied by the Einstein convention, (which is that you sum over repeated indices), i.e: [correction to index]

[tex]\Gamma^\rho_{~\mu \nu}=\sum_{\lambda=0}^{\lambda=3} \frac{1}{2} g^{\rho \lambda} (\partial_\mu g_{\nu \lambda}+\partial_\nu g_{\mu \lambda}-\partial_\lambda g_{\mu \nu})[/tex]
 
Last edited:
pervect said:
[tex]\Gamma^\rho_{~\mu \nu}=\sum_{\lambda=0}^{\lambda=4} \frac{1}{2} g^{\rho \lambda} (\partial_\mu g_{\nu \lambda}+\partial_\nu g_{\mu \lambda}-\partial_\lambda g_{\mu \nu})[/tex]

The sum should extend from 0-3, not 0-4 :)
 
Nabeshin said:
The sum should extend from 0-3, not 0-4 :)

Ooops - yes, good point, space-time has 4 dimensions, not 5. I corrected the original, for whatever it's worth.
 

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