The human brain is a wonderful instrument, capable of astounding feats of ingenuity and empathy. It struggles, however, with issues of scale: people in other countries, numbers larger than 10, really anything outside its immediate vicinity. These things are difficult for the brain to deal with. To get around such issues, it makes extensive use of metaphor. Charts, tables, maps, poems, even meticulous “fact-based” narratives, these are all metaphors that allow the brain to absorb a small amount of information and provide much of its own context.
I don’t put quotes around “fact-based” to be pejorative. My only point is that the written or spoken word, however truthful, exists in the space between approximation and analogy. “President James Garfield was assassinated in 1881” is a fact, as we understand the word “fact” to mean. But what is a president? How was Mr. Garfield assassinated? 1881 whats? We could make this sentence more precise: A man named James Garfield, who had just won 215 electoral votes in a United States presidential election and therefore led the executive branch of the United States government, was fatally shot approximately 1,881 years after Jesus of Nazareth was born.
But we knew most of that. To add the additional “facts” costs our brains a lot of effort without appreciably improving our understanding. It suffices to say “President James Garfield was assassinated in 1881,” so our brains can fill in the rest. And that’s great! It’s a real time-saver with the additional luxury of mostly representing the truth. The same can be said for a map, or a chart. We know that the coastline of Iberia doesn’t look exactly like your right fist, but that doesn’t make a zoomed-out map of Europe any less useful. On the contrary, the metaphor of the first-shaped peninsula is hugely useful (because now we can conceptualize Spain and Portugal in relation to other places) and it comes with only the tiny cost of a few degrees of precision.
Physics in particular is a discipline ripe with metaphors, and for good reason. The universe is a blisteringly complicated place, and the role of physics is to find metaphors that translate such complexity into ideas digestible by a human brain.
For example, Aristotle wrote that a stone falls to the ground because objects with a heavy “nature” simply belong at the center of the universe (which he believed to be below his feet). Isaac Newton, armed with better data, wrote that no, in fact, all objects are attracted to one another, and so the stone and the Earth both move. Albert Einstein, possessing still better data, wrote that actually, the stone and the Earth create curves in something called “spacetime” and cannot help but move along these curves. All three theories describe patterns of motion familiar to any human, but Einstein’s does the best job of predicting new observations, and so –for now– it is taken to be correct, despite being quite complex. What “really happens” when you drop a stone to the ground matters less than having an agreed-upon vocabulary for discussing it. In my view, it is unwise to think of Aristotle’s idea as simply “wrong.” Rather, his metaphor was superseded by more useful ones. Even Newton’s imperfect “classical” laws of motion are still widely taught and used for many engineering applications, because they are simpler than Einstein’s “relativistic” ones.
The problem is that physics isn’t taught that way. Rarely is physics primarily explained as the long, winding story of imperfect analogies that it is. Too often, formal physics education begins with minutia, prodding students to get the “facts” right without reflecting on the beauty of the metaphors, the marvelous breadth of both our knowledge and our uncertainty as a species. As an aspiring lifelong learner of physics, I am a sucker for these metaphors.
I need to pause here and clarify that my point is not to denigrate the importance of equations, or physics educators, or doing difficult problems in the weeds of physical systems. In fact, doing the math is often the best way to really grasp why things are the way that they are. And the people who devote their lives to helping students do that grasping deserve real appreciation. Furthermore, it would be a mistake to associate me with the worrying trend in public discourse towards mistrusting the scientific method and relying on unsubstantiated new-age theories. The metaphors of physics are powerful tools that have served us in demonstrable ways. To help the reader avoid making any mistake about where I stand, let me say firmly: science is real. It’s really just that I think physics education begins in the wrong place.
All of physics is hard to understand at first. So it seems strange to me to start students off learning about relatively mundane phenomena: blocks sliding down ramps, balls flying off cliffs, things that we as humans can already experience. Because those things are so immediate to us, our difficulty in solving them is all the more disheartening. You struggle to understand why a car slides such and such a distance, and then someone mentions quantum mechanics and you think, “Well shoot! I barely understood the car thing! How the hell am I supposed to know what holds an atom together?” Again, it is valuable to solve the (tricky!) problem of when your car skids vs. rolls vs. flips over. But in my opinion, solving that problem first reinforces the false impression that it takes a special kind of intelligence to learn about phenomena we don’t directly experience.
But anyway, all of that brings me to this blog. I love thinking, talking, and drawing pictures about physics. It’s the most intellectually joyous thing my brain gets to do, precisely because it is difficult, time-consuming, and approximate. And one of my least favorite things to hear when I mention a physics concept is the phrase, “I could never understand that.” I hear that as, “I’m embarrassed by the thought of all the questions I would have to ask before I understood that, so I’m going to pretend there’s this special innate thing about me that prevents me from understanding that.” That is a justifiable emotion, but what it misses is that the whole point of physics is not the understanding per say, but the conversation itself that leads to it; the messy exchange of experiments, pictures, metaphors –and even the odd equation– that allows a human brain to comprehend something it has no business comprehending. Particles? stars? The completely counterintuitive mechanisms that power sailboats? These things do not come pre-installed in the brain. But no postgraduate mathematical training is required to install them; only some dedicated thought.
Well, for reasons selfish and unselfish, I want to help guide some of that thought. The selfish reason is that setting aside time to explain physics concepts will make me happy in and of itself. Plus it will clarify my own thinking on those concepts, which will also make me happy. The unselfish reason is that even though writing about physics isn’t particularly easy for me, I hope reading about it will be fun and rewarding for others. My focus, at least at first, will be on very fundamental things. Namely the four ideas (time, space, matter, and energy) and the three realms (quantum, human, and cosmic) in which the four ideas manifest.
My goal regarding the reader is not to make them “smarter,” or to provide them with a repository of “facts.” My goal is to dust off a few of the mind’s rickety tracks, preparing them for the chugging and clatter brought by fresh trains of thought. To discover and share gorgeous example of the human brain bending over backwards to make sense of its surroundings. Above all, I hope to start some conversations about the metaphors that describe our lives.
Conversational Physics 