Knocking on Heaven's Door - Lisa Randall [130]
The Higgs mechanism, which is responsible for elementary particle masses, is an excellent example. As will be explained in the following chapter, the Higgs mechanism very eloquently explains how the symmetries associated with the weak force can be slightly broken. We haven’t yet discovered the Higgs boson—the particle that would provide incontrovertible evidence that the idea is correct. But the theory is so beautiful and so uniquely satisfies criteria required by both experiments and theory that most physicists believe it is realized in nature.
Simplicity is another important subjective criterion for theoretical physicists. We have a deep-rooted belief that simple elements underlie the complicated phenomena we see. Such a search for simple basic elements of which all reality is composed or resembles began long ago. In ancient Greece, Plato imagined perfect forms—geometric shapes and ideal beings that objects on Earth only approximate. Aristotle, too, believed in ideal forms, but in his case, he thought that the ideals that physical objects approximate would be revealed only through observations. Religions also often postulate a more perfect or more unified state that is removed from, but somehow connected to, reality. Even the story of the fall from the Garden of Eden presupposes an idealized prior world. Although the questions and methods of modern physics are very different from those of our ancestors, many physicists, too, are seeking a simpler universe—not in philosophy or religion, but in the fundamental ingredients that constitute our world.
The search for underlying scientific truth often involves looking for simple elements from which we can construct the complex and rich phenomena we observe. Such research often involves trying to identify meaningful patterns or organizing principles. Only with a concise realization of simple and elegant ideas do most scientists expect a proposal to have the potential to be right. A starting point involving the fewest inputs has the further benefit that it promises the most predictive power. When particle physicists consider suggestions for what might lie at the heart of the Standard Model, we usually become skeptical when the realization of an idea becomes too cumbersome.
Again, as with art, physical theories can be simple in themselves, or they may be complex compositions made up of simple and predictable elements. The end point of course isn’t necessarily simple, even when the initial components—and perhaps even the rules themselves—are.
The most extreme version of such pursuits is the search for a unifying theory consisting of only a few simple elements obeying a small set of rules. This quest is an ambitious—some might say an audacious—task. Clearly an obvious impediment prevents us from readily finding an elegant theory that completely accounts for all observations: the world around us manifests only a fraction of the simplicity that such a theory should embody. A unified theory, while being simple and elegant, must somehow accommodate enough structure to match observations. We would like to believe in a single simple, elegant, and predictable theory that underlies all of physics. Yet the universe is not as pure, simple, and ordered as the theories. Even with an underlying unified description, a lot of research will be necessary to connect it to the fascinating and complex phenomena we see in our world.
Of course, we can go too far in these characterizations of beauty or simplicity. A standard joke among students in our science or math classes involves professors who repeatedly refer to well-understood phenomena as “trivial,” no matter how complex they might be. The