•Homogeneity – matter is uniformly spread across the universe on large scales
•
•Isotropy – the universe looks the same in all directions, again strictly true on large scales
•
•Universality – laws of physics apply everywhere
in the universe (being challenged!)
•
–These lead
to the “cosmological principle” which says that any observer in any galaxy in the
universe
should see essentially the same features of the universe.