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We present a novel theory of the very early universe which addresses thetraditional horizon and flatness problems of big bang cosmology and predicts ascale invariant spectrum of perturbations. Unlike inflation, this scenariorequires no exponential accelerated expansion of space-time. Instead, the earlyuniverse is described by a conformal field theory minimally coupled to gravity.The conformal fields develop a time-dependent expectation value which breaksthe flat space so(4,2) conformal symmetry down to so(4,1), the symmetries of deSitter, giving perturbations a scale invariant spectrum. The solution is anattractor, at least in the case of a single time-dependent field. Meanwhile,the metric background remains approximately flat but slowly contracts, whichmakes the universe increasingly flat, homogeneous and isotropic, akin to thesmoothing mechanism of ekpyrotic cosmology. Our scenario is very general,requiring only a conformal field theory capable of developing the appropriatetime-dependent expectation values, and encompasses existing incarnations ofthis idea, specifically the U(1) model of Rubakov and the Galileon Genesisscenario. Its essential features depend only on the symmetry breaking patternand not on the details of the underlying lagrangian. It makes genericobservational predictions that make it potentially distinguishable fromstandard inflation, in particular significant non-gaussianities and the absenceof primordial gravitational waves.

The Pseudo-Conformal Universe: Scale Invariance from Spontaneous Breaking of Conformal Symmetry