The intuitive notion that the universe has three dimensions seems to be an irrefutable fact. After all, we can only move up or down, left or right, in or out. But are these three dimensions all we need to describe nature? What if there aree, more dimensions ? Would they necessarily affect us? And if they didn't, how could we possibly know about them? Some physicists and mathematicians investigating the beginning of the universe think they have some of the answers to these questions. The universe, they argue, has far more than three, four, or five dimensions. They believe it has eleven!

Since the 1920s, physicists have tried numerous approaches to unifying the principal natural interactions: gravity, electromagnetism

Unfortunately, physicists soon realized that general relativity in a four-dimensional space-time does not have enough mathematical "handles" on which to hang the frameworks for the other three forces.