What does it mean to state that the universe is isotropic and homogeneous?
Saying that the universe is isotropic means that there are no preferred direc-
tions in the universe; it looks the same no matter which way you point your
telescope. Saying that the universe is homogeneous means that there are no
preferred locations in the universe; it looks the same no matter where you set
up your telescope. Note the very important qualifier: the universe is isotropic
and homogeneous on large scales. In this context, “large scales” means that
the universe is only isotropic and homogeneous on scales of roughly 100 Mpc
or more.