- #1
unscientific
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Homework Statement
(a) Find the christoffel symbols (Done).
(b) Show that ##\phi## is a solution and find the relation between A and B.[/B]
Homework Equations
The Attempt at a Solution
Part(b)
[tex]\nabla_\mu \nabla^\mu \phi = 0[/tex]
I suppose for a scalar field, this is simply the normal derivative:
[tex]\frac{\partial^2 \phi}{\partial \eta^2} + \frac{\partial^2 \phi}{\partial r^2} = 0 [/tex]
Starting with the ##\eta## component:
[tex]\frac{\partial \phi}{\partial \eta} = exp() \left[ B + (A+B\eta)(-ic|k|) \right] [/tex]
[tex] \frac{\partial^2 \phi}{\partial \eta^2} = exp() \left[ -2ic|k|B - |k|^2c^2(A+B\eta) \right] [/tex]
Now for the ##r## component:
[tex]\frac{\partial \phi}{\partial r} = exp() \left[ A+B\eta \right](\vec k \cdot \hat r)[/tex]
[tex]\frac{\partial^2 \phi}{\partial r^2} = exp() \left[ -(A+B\eta)(\vec k \cdot \hat r)^2 \right] [/tex]
Equating both real parts doesn't work; It gives ##(\vec k \cdot \hat r)^2 = |k|^2 c^2##..