Can geodesics in extra dimensions solve the cosmological horizon problem? art. no. 063513

We demonstrate a non-inflationary solution to the cosmological horizon prob lem in scenarios in which our observable universe is confined to three spat ial dimensions (a three-brane) embedded in a higher dimensional space. A si gnal traveling along an extra-dimensional null geodesic may leave our three -brane, travel into the extra dimensions, and subsequently return to a diff erent place on our three-brane in a shorter time than the time a signal con fined to our three-brane would take. Hence, these geodesics may connect dis tant points which would otherwise be "outside" the four dimensional horizon (points not in causal contact with one another).