30 Acknowledgments be exploited to analyze the system better. For geometries with more features than a single hole in the center of the distribution, it would be interesting to figure out if one can find a fit to the wave function from numerical data. Such a dictionary would help us understand a lot better the relation between the geom- etry and the original quantum setup. Such an approach will obviously use more information about how the configurations were generated to infer (or reconstruct) information. Notice also that we are not considering either coarse grained geometries (statistics over multiple states that share common features) nor random statistical states in the ensemble. For such states, other techniques are available that show how hard it is to measure micro- scopic geometries [44]. Distinguishing the geometries obtained from bona-fide ’geometries’ from those obtained from random superpositions of states should also be interesting. We are currently looking into these matters. D. B. would like to thank G. Horowitz and especially L. Yaffe for many discussions on large N limits. Work supported in part by DOE under grant DE-FG02-91ER40618. [1] J. M. Maldacena, “The large N limit of superconformal field theories and supergravity,” Adv. Theor. Math. Phys. 2 , 231 (1998) [Int. J. Theor. Phys. 38 , 1113 (1999)] [arXiv:hep- th/9711200]. [3] S. S. Gubser, I. R. Klebanov and A. M. Polyakov, “Gauge theory correlators from non-critical string theory,” Phys. Lett. B 428 , 105 (1998) [arXiv:hep-th/9802109]. [4] E. Witten, “Anti-de Sitter space and holography,” Adv. Theor. Math. Phys. 2 , 253 (1998) [arXiv:hep-th/9802150]. [5] D. Berenstein, “Large N BPS states and emergent quantum gravity,” JHEP 0601 , 125 (2006) [arXiv:hep-th/0507203]. [2] S. W. Hawking, “Breakdown Of Predictability In Gravitational Collapse,” Phys. Rev. D 14 , 2460 (1976).