### Abstract

The radiation-dominated k = 0 FRW cosmology emerges as the induced metric on a codimension one hypersurface of constant extrinsic curvature in the five-dimensional AdS-Schwarzschild solution. That we should get FRW cosmology in this way is an expected result from AdS/CFT in light of recent comments regarding the coupling of gravity to "boundary" conformai field theories. I remark on how this calculation bears on the understanding of the Randall-Sundrum "alternative to compactification." A generalization of the AdS/CFT prescription for computing Green's functions is suggested, and it is shown how gravity emerges from it with a strength G4=2G5 IL. Some upper bounds are set on the radius of curvature L of AdS5. One of them comes from estimating the rate of leakage of visible sector energy into the CFT. That rate is connected via a unitarity relation to deviations from Newton's force law at short distances. The best bound on L obtained in this paper comes from a match to the parameters of string theory. It is L-& 1 nm if the string scale is 1 GeV. Higher string scales imply a tighter bound on L.

Original language | English (US) |
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Article number | 084017 |

Journal | Physical Review D |

Volume | 63 |

Issue number | 8 |

DOIs | |

State | Published - Dec 1 2001 |

### All Science Journal Classification (ASJC) codes

- Nuclear and High Energy Physics
- Physics and Astronomy (miscellaneous)

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## Cite this

*Physical Review D*,

*63*(8), [084017]. https://doi.org/10.1103/PhysRevD.63.084017