"A tantalizing idea considered since the early part of the last century is that the universe might have more than the three spatial dimensions of common experience.
In addition to the familiar left/right, back/forth and up/down, physicists have contemplated additional directions that are curled up to such a small size that they’ve so far eluded discovery.
For many years Einstein was a strong proponent of this idea. He had already shown that gravity was nothing but warps and curves in the familiar dimensions of space (and time); the new idea posited that nature’s other forces (for example, the electromagnetic force) amounted to warps and curves in additional, as yet unknown, spatial dimensions. Difficulties in applying the idea mathematically resulted in Einstein ultimately losing interest. But decades later, string theory revived it: the mathematics of string theory not only requires extra dimensions but has shown how to resolve the issues that flummoxed Einstein.
And now, remarkably, there’s a chance — albeit a small one — that the Large Hadron Collider may find evidence for the extra dimensions. Calculations show that some of the debris produced by the proton collisions may be ejected out of our familiar spatial dimensions and crammed into the others, a process we’d detect by an apparent loss of the energy the debris would carry.
The unknown is just how powerful the collisions need to be for this process to happen, a number itself determined by another unknown: just how small the extra dimensions, if they exist, actually are. The more tightly they’re curled, the harder it would be to cram anything in them and so the more energetic the required collisions.
Should the Large Hadron Collider have the power necessary to reveal extra dimensions of space — to overturn our belief that length, width and height are all there is — that would rank as one of the greatest upheavals in our understanding of the universe.
Finding what you don’t expect opens new vistas on the nature of reality. And that’s what humans, including those of us who happen to be physicists, live for."
-Brian Greene, (Excerpt: "The Origins of the Universe: A Crash Course," NY Times, 9.12.08. Image: -Max Brice, "The Large Hadron Collider's ALICE Inner Tracking System during its transport in the experimental cavern and its insertion into the Time Projection Chamber (TPC). ALICE will study the physics of ultrahigh-energy proton-proton and lead-lead collisions and will explore conditions in the first instants of the universe, a few microseconds after the Big Bang." The Boston Globe, 8.1.08).