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4
questions
1
vote
1
answer
148
views
Deriving Klein-Gordon equation in curved spacetime [closed]
I try to drive The Klein-Gordon equation for a massless scalar field in case of FRW metric:
$$
ds^2= a^2(t) [-dt^2 + dx^2]
$$
So I start by:
$$\left(\frac{1}{g^{1/2}}\partial_{\mu}(g^{1/2}g^{\mu\nu}\...
- 395
0
votes
1
answer
651
views
Klein-Gordon equation in FRW spacetime
The metric for FRW spacetime is $$ds^2=a(n)^2(dn^2 - dx^2)$$ where $dn$ is the conformal time differential form. The Klein Gordon equation in curved spacetime is $$\left(\frac{1}{g^{1/2}}\partial_{\mu}...
user310742
2
votes
1
answer
125
views
Scalar field energy density not changing with expanding spacetime
Basically, I just want to know why this scalar field's energy density does not change, even though spacetime is expanding.
A general expanding cartesian metric is used:
$$
g_{00} = -1 $$ $$
g_{11} = ...
- 57
2
votes
1
answer
359
views
Perturbation of the energy-momentum tensor: mistake in my computations or in the book?
In the book Cosmology - S. Weinberg eqauation $(5.1.28)$ is
$$
\delta T^{\mu}_{\;\;\nu} = \bar{g}^{\mu\lambda} [\delta T_{\lambda\nu} - h_{\lambda\kappa} \bar{T}^{\kappa}_{\;\;\nu} ] \tag{5.1.28}
$$
...
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