Stress-energy tensor in static cylindrical case

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Discussion Overview

The discussion revolves around the application of the stress-energy tensor in a static cylindrical coordinate system, specifically using the Weyl metric. Participants are examining the relationships between components of the stress-energy tensor and the Einstein tensor, exploring potential contradictions arising from their calculations.

Discussion Character

  • Technical explanation
  • Debate/contested
  • Mathematical reasoning

Main Points Raised

  • One participant presents a definition of the stress-energy tensor and applies it in cylindrical coordinates, leading to a result where T_{11} equals T_{33}.
  • The same participant derives from the Einstein tensor that G_{11} equals -G_{33}, which leads to the conclusion that T_{11} must equal -T_{33}.
  • Another participant finds that G_{33} equals -G_{22}, expressing skepticism about the Einstein tensor representing that of a perfect fluid.
  • There is a request for clarification regarding the apparent contradiction between the results obtained from the stress-energy tensor and the Einstein tensor.

Areas of Agreement / Disagreement

Participants do not reach a consensus, as there are conflicting results regarding the relationships between the components of the stress-energy tensor and the Einstein tensor.

Contextual Notes

Participants note potential issues with the validity of the stress-energy tensor definition in different coordinate systems, as well as the implications of using the Weyl metric in their calculations.

ArthurB
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I have some problems using this definition, maybe because it's not valid in every coordinate system:

<br /> T^{\mu\nu} = (\epsilon + p) \frac{dx^{\mu}}{ds} \frac{dx^{\nu}}{ds} -p g^{\mu\nu}<br />

since in cylindrical coordinates
<br /> x^0 =t \qquad x^1 =\rho \qquad x^2 = \phi \qquad x^3 =z<br />

using weyl metric
<br /> g_{00}= e^{2u} \qquad g_{11}=-e^{2v-2u} \qquad g_{22}=-\rho^2 e^{-2u} \qquad g_{33}=-e^{2v-2u} \qquad u=u(\rho,z) \qquad v=v(\rho,z)<br />

I obtain
<br /> T_{11}=T_{33}<br />

but from the definition of the einstein tensor I obtain
<br /> G_{11}=-G_{33}<br />

but einstein equation says
<br /> G_{\mu\nu}=8\pi k T_{\mu\nu}<br />

which in this case then implies
<br /> T_{11}=-T_{33}<br />

in contraddiction with the result obtained from the first formula.
can anyone explain?
 
Last edited:
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To make the math show up correctly, you need tex and /tex (or itex and /itex for inline equations), not latex and /latex.
 
thanks, corrected. Do you have any clue about the problem?
 
I find G33 =-G22 also.

I would not expect this Einstein tensor to be that of a perfect fluid.
 
Last edited:

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