Week 8: Evolution of Perturbations
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چکیده
We will follow Ch. 6 in Weinberg’s book quite closely. As seen therein, the exact calculations for the evolution of radiation perturbations require that we take into account the fact that Thomson scattering of photons depends on the photon polarization. To simplify and get to the basic physics results, we will assume that photons are unpolarized and that Thomson scattering is insensitive to polarization. We will also consider only scalar perturbations—the treatment of tensor perturbations is then analogous.
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