Cosmology in the Friedman Universe

Cosmology in the Friedman Universe - Cosmology in the...

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Cosmology in the Friedman Universe Before going on to galaxy formation and evolution, it is worthwhile to look at the connections between cosmological models and basic tenets of general relativity for the commonly-considered instance of an expanding Universe in the Friedman model . The connection between the world model and observables comes about from Weyl's postulate - that the wordlines of galaxies form a 3-bundle of non-intersecting geodisics orthogonal to a series of spacelike hypersurfaces. This is what is now generally meant by a comoving coordinate systems, since we appreciate that galaxies and clusters depart from this ideal through having nonzero peculiar motions. An excellent source for this material is Peebles' Physical Cosmology (Princeton 1971). Pedantically, using the relativistic coordinates x μ , a spacelike hypersurface satisfies x 0 =constant, and a worldline which follows the Weyl condition has x μ constant for μ=1,2,3. This constrains the geometry of spacetime (i.e. the fact that these exist and can be orthogonal) such that the
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This note was uploaded on 11/10/2011 for the course AST AST1002 taught by Professor Emilyhoward during the Fall '10 term at Broward College.

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Cosmology in the Friedman Universe - Cosmology in the...

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