Flow control

From hunters and gatherers to farmers and citizens, we are conditioned to be consumers of continuous physical flows. Water and air, food and warmth, these are just some of the things we need to receive regularly to sustain our existence. Our bodies can adapt to changes in flow to some extent, like a thermostat, but too much or too little of a good thing can still kill us.

Always ready to invent a simple model to explain complex realities, in the past we have explained the workings of the body as a balanced reservoir of essential fluids, or taken to extreme the idea that anything physical can be either poisonous or beneficial, depending on dosage. Although we retain some reservoirs inside, our bodies are primarily not bottles, to be filled or emptied. We are processes, and we must continue to consume as long as we live.

Modern man has learned to store materials outside of his own body. When hunting was unfavourable, and weather destroyed plant life, caches of food would help ensure survival for the tribe. As gatherers collected foods that seem to preserve best, some of these caches of foods will have started growing, all on their own. Curious beasts that we are, we discovered what seeds are, by trial and error.

More and more we relied on stored food, and gradually became obsessed with the logistics of it: How much water is in that waterskin? How much grain can we store in that cave? Can you make those clay pots bigger? Is there a way we could extract just the most nutritious parts of the plant, so we can store more of it in the same volume? And also make it last longer without spoiling? And so on, until most of us forgot that we used to hunt our food in the wilderness.

Resource anxiety, the worry that we might at any time run out of something that we need, has never left us, even though we live in the midst of historical abundance. The precursors of such ideas as ownership, budgets, and trading, might have existed in some form in the tribal era, but it was our transformation to farmers and citizens that made them real.

Economy is all about controlling the flow of goods and consumables. But to properly understand the flow of materials around the world, we need to represent them in a more handy form: currency. Even though we constantly compare incomparables, like apples and oranges at the market, we think we can compare against something that stays fixed and solid: the value of money. But of course there is nothing that is infinitely solid and fixed, all assets can be liquidized, given time.

There is one physical resource that we need to live, that cannot be stored or traded. Even the richest man in the world only has a finite time to live, and the clock ticks for everyone alive. Even though we do not know exactly how much time we have left, we know we cannot live forever.

But flow control is not just about quantitative logistics. By controlling flow as it solidifies, forms and patterns can be stored: Ink flows onto paper and dries, storing words and pictures in solid 2-D form. With some more work, we can cause clay, wax, resin, and various polymers to solidify in a desired shape (with 3-D printers, if nothing else).

Life forms are processes that consume and produce resource flows with intricate, and often efficient patterns. Evolution makes individuals compete on resources, so that natural selection can improve resource usage among the survivors. In the broadest sense, anything that is limited, acts between individuals, groups of individuals, or between them and the non-living environment, can become a contested resource for the purposes of evolution.

A page completely covered in ink is as void of information as one left blank

For example, space for storing patterns can become a contested resource, but how to measure it? It is not possible to optimize for quantity and quality at the same time: a page completely covered in ink is as void of information as one left blank. Shapes cannot be stored from just one resource, at least two are needed, like paper and ink, or wax and empty space.

Life stores its patterns efficiently, in molecules so small we cannot see them with the naked eye. To control its flowing patterns, life as we know it fluctuates somewhere between liquid and solid. DNA is a one-dimensional strand, folded for storage into big 3-D bundles, called chromosomes. The machinery of the cell will unwind these strings regularly for copying, or for protein synthesis.

Grossly simplified, the copying or expressing of DNA is a process of controlled solidification. The surrounding liquid floats abundantly with assorted building blocks, free amino acids or nucleotides. The machinery of the nucleus guides them to connect one after the other in the order determined by the strand being copied, to grow into a long 1-dimensional floating crystal chain, a transcript or copy of the original. After synthesis, proteins twist and fold into space-filling 3-D knotty shapes, to be able to perform their tasks inside or outside the cell.

The inner machinery of the cell is contained inside the cellular membrane, which is a flexible 2-D liquid crystal forming the walls of the cell. Unlike the folding-unfolding 1-D strings inside it, the cellular membrane is not a copy of anything, it is one half of the original membrane that broke in two as the parent cell divided. Like a soap bubble that keeps growing and dividing forever, the cellular membranes inside our bodies are all pieces of a cell that lived and died billions of years ago.

What does change about the walls of different cells is the intricate system of gates and filters straddling it, bundles of 3-D-folded 1-D macromolecules that the cell manufactures. These gates decide what material can flow in or out of the cell. For example, distant parts of a complex multicellular organism can communicate by sending or receiving messenger chemicals via the bloodstream. The immune system can also order cells to stop molecules it considers harmful from entering, by programming the gates in the membrane.

With our mechanistic intuition, we think of gates as solid mechanical objects and flow as matter in a liquid state. These are the kind of machines we build: silicon crystals printed with intricate systems of billions of tiny gates controlling the flow of electricity. Such machines can be very precise and efficient, but they are not very adaptive. We probably expected to find such a mechanistic system inside the cell as well, engineered to precision. That is one of the reasons why molecular biology has baffled our expectations so many times during its short existence.

For example, unlike simpler life forms, most of the DNA in a human cell is not genomic, or blueprints for proteins. Instead we have discovered in the ‘junk‘ parts a complex RNA-based regulation system for deciding what genes the cell should be expressing, and when.

We have also discovered what can only be described as life fragment parasites, lonely strands of macromolecules that travel from host cell to host cell, hijacking their replication systems to produce copies of themselves. Although these parasites usually only harm their host when in the process of jumping from one species to another, we somehow decided to call them viruses, meaning poison. (But as noted earlier, the difference between poison and medicine is dosage, not chemical composition)

Most of the cells in our bodies are not even human cells at all: the colonies of billions of single-cell organisms that live in our gut.

Proteins can apparently also be more dynamic than previously thought. Instead of folding into a deterministic 3-D shape, some proteins that our genes express do not have a native shape, but are said to be intrinsically unstructured.

Misfolded and tangled proteins get produced by our cells all the time, mistakenly or on some not-yet-understood purpose. As these proteins cannot be consumed as signals at their destinations, they accumulate as plaque in our central nervous system, which can be very harmful. But it seems that evolution has already created a mechanism, the recently discovered glymphatic system, that cleans our brains when we are not using them, during the deeper phases of sleep.

All in all, the programming language of life seems more like lisp than Fortran, in that separation between what parts are programs and what parts are data is not clean. Also, a lot of hidden garbage collection seems to be required, to recycle finite resources and thus hide the quantitative flow regulation from the reproducing parts of the organism.


The pressure to separate

We spend our lives pressed against it, and take its stability for granted. To us, Earth is the most solid foundation of all our endeavours. It provides us with various materials to build our tools from, and anchors all our structures. To contain or separate, we use walls, made from the solid substances available to us.

This kind of solidity is useful, but it has limits. Even the most rigid materials will bend and sway like rubber in large scale constructs. To move the Earth, Archimedes would need more than a place to stand on, he would need a lever of supernatural solidity. At large scales, all known materials, even so-called solids, will start behaving like fluids.

The spheroid form of a planet is the result of the fluid-like behaviour of its substance. The surface of the Earth pushes against our feet not because it is so rigid, but because the combined pressure of the planet’s own weight cannot compress the atoms inside to any smaller volume. There is nowhere for the pressure to go except outwards, and by diffusion it all evens out into a spherical form, or actually concentric spheres of different pressures and densities. Pressure increases towards the middle of the planet, up to millions of times normal atmospheric pressure; but at the same time the relative pull of gravity diminishes to none in the middle.

At the surface, where gravity is strongest, the layering is present all around us, even where we do not see it: in the strata under our feet, or above us in layers of clouds moving in different directions. The seas have layers also, with surface currents at odds with deeper ones.

Pressure is nothing more than the combined effect of countless billions of atoms colliding with one another. In free-fall, gravity gives each particle equal acceleration regardless of mass, as famously demonstrated by Galileo. But equal speed gives the larger particle a larger momentum, which is what matters in collisions.

The separation of different materials to concentric layers is the result of the continuous struggle, the harmony of battle lines. The way “up” and “down” is one and the same, only relative to the pressure of the opposing forces. Indeed, many substances circulate endlessly between layers, like the water cycle which we depend on.

"Even the posset separates unless stirred" -- Heraclitus, according to Theophrastus

“Even the posset separates if it is not stirred” — Heraclitus, according to Theophrastus

As it happens, the zero point of gravity is actually never in the exact middle of our planet. The combined center of mass of the Earth-Moon system is inside the surface of Earth, but off-center towards where the Moon happens to be at that moment. As the Earth rotates, the change in direction of the pull of the Moon causes water tides in surface waters, but also tidal movement of the earth itself.

Particles do not have to be invisibly small to behave collectively like a fluid. All that is needed is some way for the particles to flow past each other. When a container of different size objects, such as flour, nuts, or sand, is jostled or shaken, the contents get shifted so that the larger pieces are on top, and smaller ones at the bottom. Continuous vibration helps overcome static friction, but the resulting fluid is still quite viscous. It should be noted that with these kind of every-day particles, the size of the container relative to particle size would be called capillary with molecular fluids.

"Even mixed grain separates when vibrated"

“Even mixed grain separates if it is shaken” — Heraclitus paraphrased

In our solar system, we can see an even more spectacular example of solid objects arranging themselves to concentric layers over time: the rings of Saturn. In space, particles do not need to actually touch to interact with each other, they can affect each other’s orbits just by passing closely.

Substance and Form

As generalists, we constantly interpret our sensory inputs, improving on our raw senses by relying on our internal model of the world. In our mind’s eye, we typically model the physical world as objects, of various materials and shapes.

In addition to our senses and our big brains, we are uniquely equipped with hands, with which we interact with the various objects that surround us, from the moment we are born. Our hands can turn things around, bring them closer to our eyes or nose, hold them still, or discard them when they no longer hold our interest. We can use our hands to point to the thing that we are talking about, cup water in them, throw and catch objects, dig. Once we have learned to use our hands, they become almost thoughtless extensions of our will in the world.

With our hands, we can change the shape of objects. Cave paintings, bone flutes, stone tools have been discovered, tens of thousands of years old, much older than recorded history. And no doubt most of what we created then has not survived the ages: most pliable materials available, such as wood, leather, feathers, hair, will have rotted long ago and lost its form.

Any ethnographic or anthropological study of the different human tribes reveals the bewildering variety of shapes and forms that humans pose, even on their own bodies. Clothes, dyes, jewellery are a given in any society, visible embodiments of the social drive of humans. But more permanent modifications to the body can also happen, like ornamental scarring or filing of teeth, and even dangerous adjustments of the growing skeletal structure like skull-binding or neck-stretching.

It is natural for us to understand the world in terms of hylomorphism: Take a piece of some readily available material, like wood (hyle), and work (morph) it until it looks like some other object. All things that are real and physical are always combinations of material and form. In other words, matter cannot appear out of nowhere, nor disappear; it can only change form.

The internal model of the world inside the human mind is of course not subject to these restrictions. In the mind’s eye we can easily separate the shape of an object, or the properties of materials, from an object, and regard them as abstract categories of existence. An important feature of the internal model is the ability to consider possibilities that are not actually present. For example, to successfully craft an object to a desired shape we need to have some kind of a plan or idea of how it should look when it is finished.

Now in the 21st century, we can use computers to create just about any object we can think of, from a city to a molecule, view its shape on the screen while doing so, try on different materials and arrangements until we are satisfied; before sending it to a fab, perhaps on the other side of the planet, to be “3D-printed” into an actual physical object. We are not yet even close to the accurate placement of individual atoms in the manufacture of molecules, and we don’t entirely understand how arbitrary DNA might fold into a protein, but these and other details are being worked on.

Since we can use information technology to manipulate non-existing objects, and transmit their shape to the other side of the world, it would seem that information has consumed the ‘form’ part of hylomorphism. In a larger sense, the blueprints of the objects we can manufacture can also be considered mathematical formulas, or some extended category of language. In practice, digital information can be used to represent both.

The part of ‘hyle’ is played by energy in modern physics.

The part of ‘hyle’, the primary substance of all physical objects, is played by energy in modern physics. The quantity of energy in a closed system is constant, only its form can change. All matter is composed of elementary particles, quantums of energy with either mass-like or radiation-like appearance (or both).

Even with these modern refinements, the basic paradigm of hylomorphism stands: in the physical world, substance and form are always intrinsically entangled. Even though it seems that the information we store on a computer and transmit across the globe is completely immaterial, in practice the process of reliably storing or transferring digital information always consumes energy, our new hyle, in some form and quantity.

Galaxies in bullet-time

Our ancestors, lacking artificial lights and thus light pollution, would have seen the stars in the sky more clearly than most people today can. A few of them would have seemed to move continuously, what we now call planets, but most of the stars were fixed, never moving from their place in the solid, rotating canopy. Apart from the occasional falling meteor or comet, this wonderful canopy of stars would remain the most constant and unchanging part of their world.

The canopy itself is for the most part darkest black, with some lighter smudges in places. In tribal legends, some anthropomorphic invisible giant would have spilled milk while moving over the perfectly black background, creating what we still call the Milky Way.

the flowing movement that we intuitively recognize in the spilling of the Milky Way never stopped

Since then, we have discovered that there is no solid canopy, and the stars are not fixed to anything at all. The universe by and large is not solid, and the flowing movement that we intuitively recognize in the spilling of the Milky Way never stopped, it is ongoing and continuous.

Perspective affects the way we perceive motion. To a human child looking up, a flying bird seems faster than an airliner, when in fact a jumbo jet is hundred times bigger than the bird, flying hundred times faster, hundred times more distant. Our senses are simply not equipped to grasp how big and how distant the objects we see in the night sky really are.

Even though the stars are actually moving faster than any bird or aeroplane, they are so distant from us that their angular velocity is negligible from our point of view. Luckily, they are also bright enough to shine over the vast distance, serving our ancestors as beacons to navigate their vessels; although the beacons were in fact moving faster than the vessels.

Everything in the sky is falling. But because there is no universal “down” or “up”, objects either fall in all directions, possibly colliding with others, or end up falling round and round each other, in rotating patterns.

Turbulent flow produces cloud-like shapes that we recognize, in vastly varying scales of magnitude, provided that the timescale is suitable. Stellar nurseries, planetary nebulae, supernova remnants, all have provided spectacular images through modern telescopes. The original exposure times have been in minutes, and many of the famous images are also false-color combinations of several exposures at different wavelengths. Yet these images look to our eyes more like short exposures of flow on Earth, than long exposures, because of the difference in scale of the flow.

Based on these astronomical images, special effects artists have produced dazzling visualizations of galaxies and nebulae, for TV shows like “Cosmos: A Spacetime Odyssey”. To break the illusion of a fixed 2D canopy, zooming into a static picture of the sky has been replaced with flying the camera into a computerized 3D model of a galaxy. This apparent motion can make the size of these celestial objects more magnificent to the human viewer, but the timescale of these fly shots is problematic.

Movement of the camera usually implies passing of time. When the imaginary camera slowly flies into the computer model of a galaxy, it moves the equivalent of thousands of light years a second. Yet the computer simulation of the galaxy in these shots is as static as the astronomical images they are based on, with no movement in the relative positions of the stars. The resulting fly shot looks as artificial as bullet-time, a galaxy frozen in mid-sneeze, with only the camera capable of any motion.

If instead the computer simulation was good enough to realistically animate long-term changes within the galaxy, time could be shown at the same enormous scale as distance in these computer generated shots. By compressing tens of thousands of years of galactic evolution into a few seconds, while the camera moves tens of thousands of light years, the fly shots would certainly look more lively. The apparent speed of ten thousand years a second would be long enough to make visible the proper motion of all the stars, along with multiple exploding stars, sparkling along turbulently flowing spirals. Like in the solar system, the fastest motion would occur near the center of the galaxy,  blurring the orbits of star systems into lines. At this timescale, a galaxy might resemble a cyclonic storm of sparkling fire.

It is unfortunately not possible to say how realistic such an animation would actually be. We humans have known about the existence of galaxies outside of our own for about a century now, so we cannot have any long-term data about how galaxies change. We don’t even know for certain how galaxies came to have the different shapes they do, and can only make plausible guesses. It also does not help that our current physics fails at simulating galaxies with any stability unless fudge factors are used.