Over on Facebook I fell into a discussion of how scientists attempt to develop intellectual constructs that model the real world. Someone else asked, “What makes a good model?” That set me thinking.
A good model makes testable predictions, that’s a fairly pragmatic criterion. Beyond that, however, physicists like models that are simple and elegant. Underlying the search for the Grand Theory of Everything (GTE) is the notion that we should be able to develop a single mathematical model from which can be derived all known physical processes.
Currently, or so I’ve read (and I’m not an expert), there is no theory that explains both quantum mechanics and general relativity. These two basic theories have both been tested, and the test results indicate that they both accord closely with how physical processes work — but they contradict one another. The hoped-for GTE would unite them.
My question is this: Why should we assume that the universe we live in can be explained by a simple, elegant model? The visible universe is, in fact, extremely messy on almost every level. Maybe it’s messy at the level of basic physical processes too. As Walt Whitman said, “Do I contradict myself? Very well — I contradict myself. I am large. I contain multitudes.” Whitman was a poet, not a physicist. But how can we be certain that the universe does not contradict itself? The quest for a simple, elegant model that explains everything is, I would suggest, an aesthetic quest. We like simple models. But of course the universe doesn’t care what we like.
Light is both a particle and a wave. You can set up an experiment that proves light is parceled into discrete quanta, and you can also set up an experiment that proves a single photon is smeared out across space — that it’s a wave. But you can’t do both at the same time, using the same photon. Light itself is a contradiction. But the problem is not with light itself. The problem is that people don’t like contradictions. We seek simple, clear explanations. We feel satisfied when we find them, and when we can’t find them it’s like an itch: We have to keep looking.
This emotional craving is powerful, and has led to some wonderful scientific discoveries. I’m not trying to suggest that the search for understanding is a bad thing. I’m just saying, maybe it’s the nature of the universe that it will forever escape any attempt to understand it in a clear, logical manner.
Maybe this is mysticism. I’m not a mystic, but maybe if you follow your intellect carefully enough, you’ll end up in the same territory. I believe it was Haldane who said, “The universe is not only stranger than we understand — it is stranger than we CAN understand.” Yeah. That.