Is the Sum of Christoffel Symbols Equal to Their Negative in Tensor Calculus?

In summary, the conversation discusses the equation \Gamma_{\mu \nu \alpha}+\Gamma_{\nu \mu \alpha}=-2\Gamma_{\alpha \mu \nu} and its relation to the derivation of the geodesic equation. It is determined that the two sides of the equation are not equal, as shown by the definition of the Christoffel symbols in terms of the metric.
  • #1
elfmotat
260
2
Is the following true?
[tex]\Gamma_{\mu \nu \alpha}+\Gamma_{\nu \mu \alpha}=-2\Gamma_{\alpha \mu \nu}[/tex]
where:
[tex]\Gamma_{\alpha \mu \nu}=g_{\alpha \sigma}\Gamma^{\sigma}_{~\mu \nu}[/tex]

I ask because, while bored in a philosophy lecture, I decided to try to derive the geodesic equation by extremizing ∫gμνuμuνdλ, where uμ = dxμ/dλ.

I was able to arrive at the following, where aμ=duμ/dλ:
[tex]2a_\alpha = (\Gamma_{\mu \nu \alpha}+\Gamma_{\nu \mu \alpha})u^\mu u^\nu [/tex]

So, am I on the right track or did I make an error somewhere?
 
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  • #2
Nevermind, they are clearly not equal. From the definition of the Christoffel symbols in terms of the metric, I found that:

[tex](\Gamma_{\mu \nu \alpha}+\Gamma_{\nu \mu \alpha})=\partial_\alpha
g_{\mu \nu }[/tex]
This makes sense, because [itex]\nabla_\alpha g_{\mu \nu }=0[/itex].

Unfortunately for me though, this is clearly not equal to [itex]-2\Gamma_{\alpha \mu \nu}[/itex] given that:

[tex]-2\Gamma_{\alpha \mu \nu}=\partial_\alpha g_{\mu \nu}-\partial_\mu g_{\nu \alpha}-\partial_\nu g_{\mu \alpha }[/tex]
 

1. What is the Christoffel symbol?

The Christoffel symbol, or Christoffel connection, is a mathematical concept used in differential geometry to describe how a coordinate system changes along a curved surface. It is a set of numbers that represent the curvature and torsion of a surface at a particular point.

2. How is the Christoffel symbol calculated?

The Christoffel symbol is calculated using the metric tensor, which is a mathematical object that describes the distance between points on a curved surface. It involves taking derivatives of the metric tensor and performing matrix manipulations to find the Christoffel symbol values.

3. What is the significance of the Christoffel symbol?

The Christoffel symbol is significant because it allows us to calculate the covariant derivative of a vector on a curved surface. This is important in understanding the behavior of objects on curved surfaces, such as planets in orbit or particles moving through spacetime.

4. How is the Christoffel symbol related to general relativity?

The Christoffel symbol is an essential component of the mathematics used in general relativity. It is used to calculate the curvature and geodesic equations that describe the motion of objects in a gravitational field. Without the Christoffel symbol, we would not be able to accurately describe the effects of gravity on a large scale.

5. Are there real-world applications of the Christoffel symbol?

Yes, the Christoffel symbol has numerous real-world applications. It is used in fields such as physics, engineering, and computer graphics to model and understand curved surfaces and their behavior. It also has applications in machine learning and artificial intelligence, where it is used to calculate the curvature of high-dimensional data.

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