None of us has God's understanding of the Universe. At best we speculate, try to predict the logical ramifications of our speculation, then try to check whether predictions match observable aspects of our universe. That process is apparent in current efforts to determine if branes might provide a logically consistent understanding of some of the more troubling recent observations such as the accelerated rate of expansion of the universe.
An October 2007 paper by Marc Mars, José M. M. Senovilla and Raül Vera of the Universidad de Salamanca, Spain, proposes such an approach. They boldly suggest that the accelerated rate of expansion of the Universe might be an indication that our brane will flip from having three dimensions of space and one of time to having four dimensions of space. While chances are that this may eventually be found inconsistent with our observable universe, it provides a good example of one method scientists use to attempt to expand our understanding.
Access their pdf formatted proposal to read. The proposal had not been peer reviewed (the common but often time consuming procedure for identifying and correcting flaws before publication).