Copyright (c) 2013 Utah State University All rights reserved. http://digitalcommons.usu.edu/ftg_facpub Recent documents in Faculty publications en-us Sun, 27 Jan 2013 04:10:20 PST 3600 http://digitalcommons.usu.edu/ftg_facpub/1 http://digitalcommons.usu.edu/ftg_facpub/1 Fri, 07 Oct 2011 07:57:04 PDT We construct Penrose diagrams for Schwarzschild spacetimes joined by massless shells of matter, in the process correcting minor flaws in the similar diagrams drawn by Dray and ’t Hooft (Commun Math Phys 99:613–625, 1985), and confirming their result that such shells generate a horizon shift. We then consider shells with negative energy density, showing that the horizon shift in this case allows for travel between the heretofore causally separated exterior regions of the Schwarzschild geometry. These drawing techniques are then used to investigate the properties of successive shells, joining multiple Schwarzschild regions. Again, the presence of negative-energy shells leads to a causal connection between the exterior regions, even in (some) cases with two successive shells of equal but opposite total energy.

]]> Jeffrey Hazboun et al.