Everybody likes adventure stories. One of the greatest adventures of all time is happening now, in the shadowy world of fundamental physics. The characters in this story are scientists and their quest is for a prize of unimaginable value ? nothing less than the key to the universe. The most important scientific discovery of our age is that the physical universe did not always exist. Science faces no greater challenge than to explain how the universe came to exist and why it is structured the way it is. I believe that in the last few years the challenge has been met. For the first time in history, we have rational scientific theories for all existence. This revolutionary breakthrough represents an advance of unparalleled magnitude in our understanding of the world and will have profound repercussions for man''s perception of the cosmos and his place in it. All science is essentially a search for unity. The scientists by relating different phenomena in a common theory or description unify part of our bewildering complex world. What makes the recent discoveries so exciting is the fact that all natural phenomena can now be encompassed within a single descriptive scheme.