An interesting application of warped 5th dimension has been developed by Lisa Randall. In this model, the 5th dimension is located in between two 3-D branes. It is found that the extra dimension is severely warped in the form of de Sitter space with positive curvature by the presence of bulk and brane energy even though the branes themselves are completely flat (see Figure 10s). The strength of gravity depends on the position of the 5th dimension. As shown in Figure 10s (in term of graviton's probability function), it can be very strong on the Gravitybrane but becomes feeble on the Weakbrane where all the forces and particles in the Standard Model are confined. Only the gravitons can move anywhere in the branes and in the bulk. This model explains why gravity is weak in our world although it can be Figure 10s Warped 5-D [equations and images at http://universe-review.ca/I15-71-LisaRandall1.jpg&imgrefurl=http://universe-review.ca/R15-17-relativity.htm&h=450&w=384&sz=36&hl=en&start=14&um=1&tbnid=26auiPISaR7vIM:&tbnh=127&tbnw=108&prev=/images%3Fq%3DLisa%2BRandall%26um%3D1%26hl%3Den%26rls%3Dcom.microsoft:*:IE-SearchBox%26rlz%3D1I7TSHB%26sa%3DX] very strong in another brane. It also introduces a new way to solve the hierarchy problem of huge difference in mass between the Planck scale and the Electro-weak scale. If the Planck scale mass is set at the Gravitybrane, then the mass of particles on the Weakbrane would be reduced by a factor of 1016 to the Tev range as expected.
No, it’s not redundant. It echos a few things I’ve heard about theories of gravity, but really anything beyond Einstein’s theories is just hypothetical. Without being really into it, actually, it sounds ridiculous. But an outsider shouldn’t judge...