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Homework Statement
Metric ansatz:
[itex]
ds^{2} = e^{\tilde{A}(\tilde{\tau})} d\tilde{t} - d\tilde{r} - e^{\tilde{C}(\tilde{\tau})} dΩ
[/itex]
where: [itex]d\tilde{r} = e^{\frac{B}{2}} dr[/itex]
Homework Equations
How to calculate second fundamental form and mean curvature from this metric?
The Attempt at a Solution
Metric tensor:
[itex]g_{00}= e^{\tilde{A}(\tilde{\tau})} [/itex]
[itex]g_{11}= -1 [/itex]
[itex]g_{22}= - e^{\tilde{C}(\tilde{\tau})} [/itex]
[itex]g_{33}- e^{\tilde{C}(\tilde{\tau})} sin^2 θ [/itex]
Second fundamental form:
[itex]h_{ij}= g_{kl} \Gamma^{k}_{ij} n^{l}[/itex]
where:
[itex]i, j, k, l = 0, 1, 2, 3[/itex]
[itex]n^{l} = [/itex]normal vector [itex]= (0, 1, 0, 0)[/itex]
so:
[itex]n^{0} = 0[/itex]
[itex]n^{1} = 1[/itex]
[itex]n^{2} = 0[/itex]
[itex]n^{3} = 0[/itex]
Second fundamental form:
[itex]h_{ij}= diag (\frac{1}{2}e^{\tilde{A}}\tilde{A'}, 0, \frac{1}{2}e^{\tilde{C}}\tilde{C'}, sin {θ} cos {θ}) [/itex]
Mean curvature:
[itex]h = g^{ij}h_{ij}= \frac{1}{2}\tilde{A'}-\frac{1}{2}\tilde{C'}-e^{-\tilde{C}}cot {θ}[/itex]
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