Visiting a particle accelerator is like a religious experience, at least for Nima Arkani-Hamed. His revolutionary ideas about the way the universe works will finally be put to the test this year at Switzerland's Large Hadron Collider, which will be the world's most powerful particle accelerator.The accelerator, estimated to cost between $5 billion and $10 billion, could provide answers to questions physicists have had for decades.

Arkani-Hamed has had a hand in explaining how the world can operate according to Einstein's theory of general relativity, which describes the universe on a very large scale, and at the same time follow quantum mechanics, laws that describe the universe on a scale smaller than the eye can see. Some of the key mysteries that stem from these clashing theories include why gravity is so weak, relative to the other fundamental physical forces such as electromagnetism and why the universe is so large. These issues come up because on an inconceivably small scale, the particles that make up our world seem to behave completely differently than one might imagine. For example, if you are driving a car, your GPS tells you where you are, and your speedometer tells you how fast you are moving. But on the scale of particles like electrons, it is impossible to know both position and speed at once; the very act of trying to find out requires incredible amounts of energy. If it takes so much energy just to try to pin down a particle, then, in theory, all particles should have temporary energy changes around them called "quantum fluctuations." This energy translates into mass, since Einstein famously said that mass and energy are interchangeable through the equation E=mc2. "It makes it extremely mysterious that the electron, or indeed, everything else that we know and love and are made of, isn't incredibly more massive than it is," Arkani-Hamed said.

A theory that has emerged in recent decades that claims to bring some relief to physics mysteries like these is called superstring theory, or string theory for short. Previously, scientists believed that the smallest, most indivisible building blocks of our world were particles, but string theory says the world is made of extremely small vibrating loops called strings. In order for these strings to properly constitute our universe, they must vibrate in 11 dimensions, scientists say. Everyone observes three spatial dimensions and one for time, but theoretical models suggest at least seven others that we do not see. Arkani-Hamed proposed, along with physicists Savas Dimopoulos and Gia Dvali, that some of these dimensions are larger than previously thought -- specifically, as large as a millimeter. Physicists call this the ADD model, after the first initials of the authors' last names. We haven't seen these extra dimensions because gravity is the only force that can wander around them, Arkani-Hamed said. String theory has come under attack because some say it can never be tested; the strings are supposed to be smaller than any particle ever detected, after all. But Arkani-Hamed says the Large Hadron Collider could lead to the direct observation of strings, or at least indirect evidence of their existence. In fact, by slamming particles into one another, the Large Hadron Collider may detect particles slipping in and out of the dimensions that Arkani-Hamed has worked on describing.