Question

Imagine cosmologists observe a bunch of thermal photons emitted at age $t_1$ of the universe, when the universe's temperature was $T_1$. They also observe a bunch of thermal photons emitted at age $t_2$ when the universe's temperature was $T_2$. Show that the temperature $T_3$ that the cosmologists infer for both bunches of photons will be the same.

          Imagine cosmologists observe a bunch of thermal photons emitted at age $t_1$ of the universe,
when the universe's temperature was $T_1$. They also observe a bunch of thermal photons
emitted at age $t_2$ when the universe's temperature was $T_2$. Show that the temperature $T_3$
that the cosmologists infer for both bunches of photons will be the same.

Imagine cosmologists observe a bunch of thermal photons emitted at age t1 of the universe,
when the universe's temperature was T1. They also observe a bunch of thermal photons
emitted at age t2 when the universe's temperature was T2. Show that the temperature T3
that the cosmologists infer for both bunches of photons will be the same.

Added by Gregorio G.

An Introduction to Modern Astrophysics

Bradley W. Carroll, Dale A. Ostlie 2nd Edition

Chapter 29

Instant Answer

Solved by Expert Deepak Jangra

Step 1

The temperature of the universe at a given age t is determined by the relationship between the age of the universe and its temperature. This relationship is described by the cosmological model, such as the Big Bang model. Show more…

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Imagine cosmologists observe a bunch of thermal photons emitted at age t of the universe when the universe's temperature was T. They also observe a bunch of thermal photons emitted at age t when the universe's temperature was T2. Show that the temperature T3 that the cosmologists infer for both bunches of photons will be the same.