The power of a good theory

There's a new set of articles buzzing around Facebook that seem to indicate that the case is "closed" on the allegedly faster-than-light (or "superluminal;" I learned that word this past year, though it seems my computer's dictionary hasn't) neutrinos. After all the controversy, CERN's Sergio Bertolucci has made the excellent point that the story has "given people the opportunity to see the scientific method in action."


I hope, in particular, that this story shows the public the power of a good theory.


I am a theoretical physicist, working on the side of the scientific method--essentially, model development and exploration--that most of the public (most notably, students) would rather gloss over. There's a lot of math, a lot of words, no "real-world" laboratory set-up, and very few cool pictures (and the cool pictures that do exist are computer generated and therefore to be considered suspect). "Show me how it works!" the experiment-preferring public cries, followed by squeals of joy when it looks like the prevailing theory (in this case, relativity) might be overturned by new "real" evidence (in this case, faster-than-light neutrinos).


Why do so many people seem averse to theory? Why is there such a furor when a prevailing theory seems to be disproved? I can't answer those questions for sure (especially since I have loved theory since I finally cracked SOHCAHTOA at a church chalkboard late one cold October night in my junior year of high school), but I do have a few ideas.

1. Many people don't like math: They don't like having to follow it or do it.
2. Experiments are "cooler" than theory (until, of course, you have to mathematically analyze the data, which is why I think many students prefer demonstrations, not experiments). 
3. Many people have been taught that the only kind of science is experimental science. (I think this statement is incomplete, as described below.)
4. Many people simply do not understand the power of a good theory.

Theories are more than esoteric cogitations of "the way things ought to be." They're a logical exploration of the implications of our underlying assumptions--assumptions which usually come from previous experimental results. Sometimes, the explorations are short-lived: For example, we spent one day on relativistic quantum mechanics in graduate school, just long enough to find the infinity that showed its invalidity. Sometimes, the explorations take a long time: We're still figuring out how to successfully formulate string theory. But once we've formulated the principles, we apply a reasoning process (ideally in the form of mathematical proof/derivation), and arrive at applications that have some testable qualities. These three pieces (well-formulated and well-founded principles, sound reasoning process, and testable applications) are essential to any good theory.

Take, for example, electromagnetic theory (which I get to teach at the junior level again this coming fall). All of the principles of the model (stationary point charges emit electric fields radially outward, a constant straight current produces circular magnetic fields around it, and changing electric or magnetic flux induces a magnetic or electric field, respectively, and magnetic "charges" don't exist) are based on experimental observations over hundreds of years. We (theorists) take those principles to develop applications of them, most notably optics, radiation, materials properties, circuits, and relativity.

We develop those applications as a way of saying, "If the underlying principles of this theory are correct, and the reasoning we've employed is sound, then in this situation (say, a particle approaching the speed of light) we should observe this behavior (say, the particle being unable to exceed the speed of light)." If you put it the other way, we're saying, "If we observe a certain behavior (say, a particle seeming to travel faster than the speed of light), then either the underlying principles are incorrect, or the reasoning we've employed is flawed."

And therein lies the power of a good theory: When you've confirmed the underlying principles time and again, and checked and rechecked the reasoning that leads to the applications, the theory (the principles, reasoning, and application) helps us know when to doubt a scientific claim.

When these results came out last year claiming superluminal speeds, most theorists knew not to be alarmed but rather to approach them with caution. Why? Because we have a powerful theory that says otherwise. It's not a matter of blind dogma to say that neutrinos can't exceed the speed of light, it's the result of a powerful theory that will require more than one experiment to topple. To put it another way, let's trace the story backwards: These neutrinos seemed to be travelling faster than the speed of light, which is supposed to be impossible according to the theory of relativity, which is not something that Einstein simply cogitated one day. The theory of relativity is built on the nature of electromagnetic waves, which are themselves a result of Maxwell's equations, which are built upon centuries of experiments. (I refer to the timespan not to say that we should favor old over new, but to contrast the amount of experimental support.)

So will this confirmation of electromagnetic theory result in a greater appreciation of theory for the common culture? Probably not. But at least theorists have a good recent example of the power of their work.