EDWIN HUBBLE (1889-1953)

“...if we see the nebulae all receding from our position in space, then every other observer, no matter where he may be located, will see the nebulae [but not the same nebulae] all receding from his position. However, the assumption is adopted. There must be no favoured location in the Universe, no centre, no boundary; all must see the Universe alike. And, in order to ensure this situation, the cosmologist, postulates spatial isotropy and spatial homogeneity, which is his way of stating that the Universe must be pretty much alike everywhere and in all directions.”  [From The Observational Approach to Cosmology (Hubble, E. P., 1937), p. ___.]