Thermal History of the Universe
•Radiation-Dominated Universes
–So, does the BB radiation have the right temperature dependence as a function of z?  That is, T = T0(1+z)?
–Yes!  Keck spectra of fine structure in C I absorption lines associated with damped Ly alpha absorbers.  Two cases, z=1.766 shows T = 7.4 K, and z=1.973 shows T=7.9 K.
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