||For many years, physicists believed that extra dimensions were acceptable, but only if they were finite in size, either curled up or bounded between branes. An infinite extra dimension was supposed to destablilize everything around us. It is now known that infinite extra dimension from a single brane (like our 3D brane) is possible if that extra dimension is heavily warped so that the gravitons are localized near the brane in a small region no more than the Planck length scale of 10-33 cm (see Figure 09t).
Thus, instead of the requirement for a heavily curved space-time in our 3D universe, or a folding one such as shown in Figure 09k, a model can be conceived such that the extra dimension in the bulk is seriously warped. It is found that the extra dimensions can be distorted by exotic matter in such a way that anything moving through the bulk can travel faster than the speed of light. Such off-brane short cuts can appear as "closed time-like curves" (CTC) as shown in Figure 09q.