We present an explicit exact solution of Einstein’s equations for an inhomogeneous dust universe with cylindrical symmetry. The spacetime is extremely simple but nonetheless it has new surprising features. The universe is “closed” in the sense that the dust expands from a big-bang singularity but recollapses to a big-crunch singularity. In fact, both singularities are connected so that the whol...

A large class of $\Lambda < 0$ cosmologies have big-bang / big crunch spacetimes with time-symmetric backgrounds and asymptotically AdS Euclidean continuations suggesting a possible holographic realization. We argue that these models generically time-dependent scalar fields, can lead to realistic at the level homogeneous background geometry, an accelerating phase prior turnaround crunch. first ...

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Cosmological solutions of gravity coupled to scalar fields, with arbitrary scalar potential, were recently shown to be geodesics in an appropriately augmented, and conformally rescaled, target space. Here we obtain these geodesics as solutions of the Euler-Lagrange equations of a relativistic particle action. As an application, we find some exact (flat and curved) cosmologies for models with N ...