Imagining Complex PhenomenaSun 15 February 2015
I'm a fairly visual person and tend to think with images. I often imagine physical scenarios representing abstract concepts or phenomena. To a certain extent everyone does this, but I can't help but think this type of behavior is more common with people engaged in science and research.
My primary visual metaphor for Chemical Engineering is a series of buckets connected by pipes. Chemicals flow through the pipes and the buckets fill and empty over time. The core classes of Chemical Engineering each reflect one aspect of this system. Mass and energy balances cover the basic premise of quantifying how buckets fill and empty. Thermodynamics predicts what chemical reactions should happen when chemicals are mixed inside a bucket and reaction kinetics estimates how fast the reactions take place. Fluid dynamics taught us how liquid moves through the pipes and control theory explains how to open and close valves to get the right flow rates.
Studying Chemical Engineering, in turn, gave me a set of mental images with which to understand biology. When I first started studying the effects of stress on the 1mm long worm C. elegans, I immediately focused on the section of the worm that most resembled a chemical production plant: the reproductive system. In C. elegans, cells flow in a tube through different stages of development and their flow rate is regulated by a feedback loop and the equivalent of a valve. The similarities between how the worm grows and lays its eggs and a mass production facility are uncanny.
As I study more aspects of biology I've been regularly increasing my set of mental images. Cells in a living organism, for example, are like water balloons buried in a giant pot of spaghetti. The spaghetti represents the extracellular matrix, a tangled mass of polymers that makes up most of the structure inside living tissue. The cells, like water balloons, have 2D surface with a certain amount of elasticity and ability to change shape. The structure inside the cells, however, is like the scaffolding of a circus tent. Microtubules and actin filaments span the cell like long ropes pulling the cell walls inward. The shape of the cell is determined by the balance of forces from the push of the spaghetti outside the cell walls, the pull of the interior circus scaffold, and the internal pressure of the water balloon.
As we get smaller, the processes become trickier to accurately imagine. Proteins, for example, are simultaneously like ribbons, people jumping around in a mosh pit, sticky tape, switches, and encoded messages. Each of these visual images helps me think of what a protein is in a different context. When I picture protein structure and how it folds into its native conformation, I picture a long red felt ribbon being tied into a knot. However, when I imagine proteins interacting with their immediate environment I picture a mosh pit of flailing people at a heavy metal concert. The people jump around pushing and colliding with each other in a tight crowded space. And then, when I have this image, I try and stretch this image to incorporate more features that are present in the real system.
A protein’s environment inside a cell is three dimensional, so I imagine the mosh pit in a large space station, where the collisions and flailing happen in zero gravity. To incorporate the differences in size between proteins I picture a continuum of people with vastly different sizes bouncing off each other in space. There are tiny pixies only a couple inches tall, dwarves, elves, people, and giants the size of a room. But even so, the shapes are too uniform. So I mix in some whales, squids, rocks, bushes, and trees. The space station is so full that the volume occupied by animals and objects is just as large as the volume of air between them. Everything is flailing and moving. And yet, somehow, the proteins inside of a cell still manage to accomplish a wide variety of specialized tasks.
Even without getting into the imagery of how proteins are like sticky tape, switches or encoded messages, you can see we have a problem. None of the images completely fit what is really going on. Each image only fits some of the aspects of what was occurring and to extend the metaphor so that it fits, I need to make the visual imagery more and more ridiculous. Really, that’s the fun part.
Richard Feynman has a great way of describing how we match visual metaphors with reality in his Fun to Imagine lecture. This is just a clip, but if you have time, I highly recommend watching the whole thing.
While the images don't completely reflect the phenomena, the best we can really hope for is fluidity in switching between mental images. Mixing metaphors may be frowned upon in writing, but they become necessary for explaining some of nature's weirder phenomena. The wave-particle duality of a light photon is probably the most famous example.
I find these mental images enormously helpful. But again, they only hold true for certain aspects of the process I'm trying to imagine. Anyone else trying to use my set of visual metaphors might focus on the wrong aspects of the imagery and become utterly confused. Despite this pitfall, the ability or inability to imagine a phenomena is the difference between interest and boredom. Given how dull many of the lectures are in basic science classes, the introduction to new concepts could benefit from an infusion of ridiculous imagery.