Theoretical Framework
Section 5.1, the “Cosmological Principle”
Isotropic, homogenous, uniform expansion
Can write relativistic equations in different
forms (famous names cited here…)
Weyl’s postulate:  “The particles of the
substratum (representing the nebulae) lie in
space-time on a bundle of geodesics
diverging from a porint in the (finite or
infinite) past.”