Simplifying Linearized Equations in GR Using Gauge Transformations

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SUMMARY

The discussion focuses on simplifying the linearized field equation in General Relativity (GR) using gauge transformations. The original equation, represented as G_{ab}^{(1)} = -\frac{1}{2}{\partial ^c}{\partial _c}{{\bar \gamma }_{ab}} + {\partial ^c}{\partial _{(b}}{{\bar \gamma }_{a)c}} - \frac{1}{2}{\eta _{ab}}{\partial ^c}{\partial ^d}{{\bar \gamma }_{cd}} = 8\pi {T_{ab}}, can be simplified to {\partial ^c}{\partial _c}{{\bar \gamma }_{ab}} = -16\pi {T_{ab}} through the gauge transformation {\gamma _{ab}} \to {\gamma _{ab}} + {\partial _b}{\xi _a} + {\partial _a}{\xi _b}. The discussion also clarifies the relationship between {{\bar \gamma }_{ab}} and {\gamma _{ab}} as well as the metric tensor {g_{ab}}.

PREREQUISITES
  • Understanding of General Relativity (GR) principles
  • Familiarity with linearized field equations in GR
  • Knowledge of gauge transformations in theoretical physics
  • Basic understanding of tensor notation and operations
NEXT STEPS
  • Study the derivation of linearized field equations in General Relativity
  • Explore the implications of gauge transformations in GR
  • Learn about the role of the metric tensor in GR
  • Investigate the physical significance of the energy-momentum tensor {T_{ab}} in GR
USEFUL FOR

The discussion is beneficial for theoretical physicists, graduate students in physics, and researchers focusing on General Relativity and its mathematical foundations.

Psychosmurf
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I need some help with a derivation in GR.

The linearized field equation in GR is:

G_{ab}^{(1)} = - \frac{1}{2}{\partial ^c}{\partial _c}{{\bar \gamma }_{ab}} + {\partial ^c}{\partial _{(b}}{{\bar \gamma }_{a)c}} - \frac{1}{2}{\eta _{ab}}{\partial ^c}{\partial ^d}{{\bar \gamma }_{cd}} = 8\pi {T_{ab}}

How would I use the gauge transformation

{\gamma _{ab}} \to {\gamma _{ab}} + {\partial _b}{\xi _a} + {\partial _a}{\xi _b}

to simplify the linearized equation to:

{\partial ^c}{\partial _c}{{\bar \gamma }_{ab}} = - 16\pi {T_{ab}}?

EDIT: I should also mention:

{{\bar \gamma }_{ab}} = {\gamma _{ab}} - \frac{1}{2}{\eta _{ab}}\gamma

\gamma = \gamma _a^a

and

{g_{ab}} = {\eta _{ab}} + {\gamma _{ab}}
 
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Nvm. I figured it out.
 

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