CP => it must be possible to define a time coord such that at any given instant, these conditions are identical everywhere in the universe => the existence of a preferred cosmic time b) The only possible type of relative motion btwn points in the universe is an expansion or contraction of the universe as a whole
Cosmology and General Relativity According to the theory of general relativity, gravity is caused by the curvature of space-time The effects of gravity on the largest cosmological scales should be related to the curvature of space-time The curvature of space-time, in turn, is determined by the distribution of mass and energy in the universe
Cosmology Standard Model ENCYCLOPEDIA OF ASTRONOMY AND ASTROPHYSICS COSMOLOGY in the modern sense of quantitative study of the large-scale properties of the universe is a surprising-ly recent phenomenon The ?rst galaxy RADIAL VELOCITY (a blueshift, as it turned out) was only measured in 1912, by Slipher It was not until 1924 that Hubble was
Homogeneity and isotropy < M, g > is spatially homogeneous, iff there is a foliation of space-time into space-like hypersurfaces Ht with the following property: For each t and each pair of events p, q
cosmology are introduced as needed Unfortunately, the National Bureau of Standards has not gotten around to establishing a standard notation for cosmological equations It seems that every cosmology book has its own notation; this book is no exception My main motivation was to make the notation as clear as possible for the cosmological novice
universe at large scales, and then define a cosmic time t as what is measured by a comoving standard clock We want to examine, however, the physical