No open or flat bouncing cosmologies in Einstein gravity
@article{Parikh2015NoOO, title={No open or flat bouncing cosmologies in Einstein gravity}, author={Maulik Parikh}, journal={Journal of High Energy Physics}, year={2015}, volume={2015}, pages={1-11} }
A bstractWe show that, to first approximation, strings cannot propagate in bouncing open or flat Friedmann-Robertson-Walker universes. Specifically, the Virasoro constraint translates to the Ricci convergence condition in spacetime at leading order in the alpha-prime expansion. Thus one must go beyond minimally-coupled classical Einstein gravity in order to find bounce solutions that could be consistent with string theory. We map out some remaining possibilities for finding string-compatible…
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