The Irreversible Nature of All Things
Why make your bed? Why waste the time laying your linens and arranging your pillows just to inevitably throw them back into disorder? As someone who tries to make my bed every day, even just a couple hours before going to sleep, I find it is more a matter of principle than practicality. Unlike brushing your teeth or doing the dishes, where the act of cleaning prevents the growth of harmful bacteria, neglecting to make the bed doesn’t seem to culminate into any severe consequence. The level of disorder in your bedroom surely doesn’t rise every time you forgo the chore of making the bed. So why is it that our mothers are so insistent that we perform organization for organization's sake? A psychologist might suggest that completing a small task at the beginning of the day sets the stage for future productivity, or that there is some delayed gratification in climbing into your tidy bed at the end of a long day. While these explanations likely carry some weight, I’d argue that the reason we make our beds in the morning can be explained by one of the most fundamental governing principles of our universe - entropy.
In the study of thermodynamics, we use various properties to describe the state of a system. Most of us probably have a basic understanding of temperature, pressure, and volume. These properties aren’t particularly abstract and can be easily related to our own personal experiences. We can walk outside and involuntarily measure the relative temperature of the air from one day to the next. We can inflate a balloon until its internal pressure overcomes the rubber’s intermolecular bonds, causing it to burst. We can take a lemon and a lime and from visual inspection deduce that one takes up more space. Another fundamental thermodynamic property is energy. Energy can take many forms, from the kinetic energy in a rolling wheel to the potential energy in a loaf of bread. The abstract idea of energy has transcended beyond thermodynamics into a colloquial analog for stamina and spirit. Beyond temperature, pressure, volume, and energy, entropy is a more elusive thermodynamic property that renders the spinning wheel static and brings the bread to a rotten end.
Most thermodynamic textbooks define entropy as the measure of disorder within a system. Take a block of ice, in which all of the molecules are neatly arranged into a solid crystal lattice. Now consider placing this block of ice into a sealed container, where the temperature of the ice is raised until the block has melted and vaporized into a cloud of gas. Where the water molecules were once tightly packed, they now bounce around in seemingly random motion. By raising the temperature of the system, the disorder and thus the entropy of the system has increased. Unlike mass and energy, which must always be conserved, the second law of thermodynamics expands on entropy’s definition of disorder, stating that the entropy of any isolated system undergoing a real process must necessarily increase. As ash cannot turn back to wood, and an egg cannot return to its shell, entropy dictates the direction of a process. Entropy tells time.
In his 1944 book What is Life? The Physical Aspect of the Living Cell, Austrian-Irish physicist Erwin Schrödinger postulates entropy’s role in governing the natural processes of living organisms. In chapter six titled “Order, Disorder and Entropy,” Schrödinger argues that living organisms circumvent the Second Law by reducing their own internal entropy at the expense of the surrounding environment. He illustrates this idea by comparing a living organism to an inanimate system. Schrödinger states that a collection of inanimate particles will eventually reach a state of thermal, chemical, and electrical equilibrium - a state of maximum entropy. Conversely, Schrödinger explains that a living organism engages in the metabolic exchange of matter and energy, “freeing itself from all the entropy it cannot help producing while alive.” By consuming food and oxygen, living organisms maintain a steady internal entropy, increasing the entropy of the surrounding environment. Through this metabolic exchange, the living organism deviates from an equilibrium state of high entropy. Perhaps making the bed is but an extension of our biological obligation to minimize internal disorder.
Four years ago, I embarked on the perilous journey to become an aerospace engineer. In solving the problems that allow us to traverse the skies and send rovers to Mars, we make assumptions to produce simplified models of real systems. In the analysis of a jet engine, we might assume that none of the heat generated through combustion is lost to the surrounding air. In modeling an orbiting satellite, we might choose to neglect the presence of gas particles above a certain altitude. These assumptions allow us to reduce an infinitely complex problem into something more manageable. I sometimes like to don the rose-tinted glasses and think back to my highschool physics classes, where the pesky forces of friction and air resistance could be cast to the wayside. The world seems so much simpler when you ignore irreversibility. We neglect friction not to suggest that it does not exist or that its effects are negligible, but because it is convenient to do so. Convenience comes at a cost, and the error induced by assumption eventually accumulates into significance. Humanity’s progress is rooted in irreversibility. Automobiles, power plants, jet engines, and rocket thrusters are all driven by the same inherently irreversible process - turning fuel to fire.
When engineers design systems, they must consider irreversibility, and develop subsystems to combat it. When we design turbojet engines capable of accelerating particles to supersonic speeds, we must also design cooling systems so that our engine does not melt into a puddle of molten irreversibility. The engine’s value lies not in the matter from which it is made, but in how the matter is arranged. If the cooling system fails, the mission fails. As the humbled owner of a twenty-year-old Land Rover, I can attest to the tribulations of a compromised cooling system, and the rippling propagation of chaos that follows. Beyond being left stranded on the side of the road, one of the more depressing consequences proposed as a result of the Second Law is “heat death.” In the 1850s, Lord Kelvin argued that the universe will eventually reach a lifeless state of thermodynamic equilibrium - a state of “chaotic changelessness” (Eddington). I find this proposal rather grim. We won’t be around to see it, but it seems no less a shame - the end of a universe. The inevitability of a universal equilibrium remains contested, with our own mortal condition begging us to reject it.
At first glance, entropy seems to have an inherently negative connotation. Irreversibility is unsettling. Wouldn’t it be nice if the sands of time could flow both ways - if the shattered glass could be unbroken and the regretted words could be unsaid? There’s no way around irreversibility, but what if irreversibility is what makes us special? What if irreversibility could be beautiful? In his 1948 paper “A Mathematical Theory of Communication,” American mathematician Claude Elwood Shannon proposes a new definition of entropy as a means of quantifying uncertainty. Imagine you’re playing a game of twenty questions, and you’re trying to think of an oddly specific word that your opponent will have trouble guessing. Surely you would never choose the word “animal” in a game of twenty questions, as it would take far fewer questions to guess than something specific like “salamander.” The more specific word takes more questions to determine, and is more uncertain to the guesser. Shannon quantifies the uncertainty of an event with the information required to convey its outcome, borrowing the term “entropy” as a measure of this uncertainty. Using Shannon’s definitions, we see that the more likely event has less associated entropy, and takes less information to convey. But how does Shannon’s information entropy relate to its classically defined counterpart?
In his “Gaia Hypothesis,” James Lovelock postulates Earth as a giant self-regulating superorganism. From a thermodynamic standpoint, Lovelock explains that information is a measure of disequilibrium. Comparing the chemical and thermal properties of Earth’s atmosphere with the probabilistic equilibria of a “lifeless Earth,” Lovelock highlights life’s tendency to deviate from a probabilistic entropy in order to facilitate its own existence. With relatively low carbon dioxide levels and high oxygen content, Earth’s atmosphere deviates from the expected chemical equilibrium. Lovelock further suggests that life’s first task was to sense the chaotic changes in its own environment and correct them before being swept back into inanimacy. Lovelock’s analyses point towards a connection between life’s cycle of self-preservation and an information-rich disequilibrium. Living organisms decrease their own local entropy at the expense of the surrounding environment, all the while producing information. Our unprecedented production of information indicates the overwhelming unlikeliness of our existence. At our core, we aren’t so unlike the entropic engines enabling our greatest achievements. We consume fuel, and in exchange, do work on our surroundings. Unlike a jet engine or a power plant, however, the beauty of the human machine lies not in the work we do, but in the information we convey. Every book ever bound and every house ever built was a conscious rearrangement of otherwise orderless mass.
It is odd to think of life on Earth having a discrete “beginning” - this is almost as esoteric a thought as the dawn of time itself. As mere mortals on this Earth, life and time are one in the same. Like a dream, our own existence is of inconceivable origin. Lovelock’s descriptions of atmospheric conditioning suggest that the emergence of single-celled microbes opened the floodgates for future life. Before the mechanics of reproduction were well understood, Charles Darwin proposed a means through which these prehistoric microbes evolved into the multitude of organisms alive today. In his groundbreaking book The Origin of Species, Darwin suggested that random mutations may affect an organism’s aptitude for survival, and that the mutations that increase an organism’s aptitude for survival are more likely to be passed to the next generation. Unbeknownst to Darwin, we now know that these mutations are physically encoded and passed from one generation to the next via DNA. In essence, DNA is a means of preserving information and passing it from one organism to another.
Similar to Lovelock’s proposal that prehistoric microbes conditioned Earth’s atmosphere and produced information, Darwin’s theory of evolution underlines life’s ability to accumulate and transfer information, decreasing local uncertainty at the expense of the greater system . Then on an evolutionary scale, what makes humans different from all other forms of life on Earth? It is not brains or brawn that tell a man from a mandrill, but rather our ability to maintain, manipulate, and manufacture information. The human ability to collect and convey dense information across a variety of mediums is what makes us unique. Beyond spoken and written communication, we have become exceedingly good at manufacturing means for communication that far exceed our physical bodies. We can move our fingers up and down and tell someone on the other side of the world what we ate for breakfast this morning.
We accumulate information to mitigate uncertainty and maintain order in an increasingly chaotic universe. In our efforts to minimize entropy at a local scale, we offload our chaos into the surrounding environment. The convenient assumption that the bounds of our system do not extend beyond ourselves is no longer valid. Without regard to the cooling of our incessant engine, our mission is destined for failure. There will come a point when Earth’s ability to adapt to human-induced disorder will waiver to the point of catastrophic irreversibility. So what do we do? We cannot turn the arrow of time or put grapes back on the vine, but we can make our beds in protest of the irreversibility that will eventually consume us.
References
Biradar, V. K., Sudarshan, D., Sanjay, M. K., SaiBaba, SandeepInamati (2017, November). Heat Death of the Universe. International Journal of Engineering Research in Mechanical and Civil Engineering, 2(11). https://www.technoarete.org/common_abstract/pdf/IJERMCE/v4/i11/Ext_81294.pdf
Darwin, C. (1999). On the Origin of Species by Means of Natural Selection. Project Gutenberg. https://www.gutenberg.org/files/2009/2009-h/2009-h.htm (Original work published 1859)
Eddington A. S. (1948). The Nature of the Physical World. Cambridge University Press. https://henry.pha.jhu.edu/Eddington.2008.pdf (Original work published 1928)
Lovelock, J. E., & Margulis, L. (1973, August 20). Atmospheric homeostasis by and for the biosphere: The gaia hypothesis. Oxford University Press. https://www.tandfonline.com/doi/epdf/10.3402/tellusa.v26i1-2.9731?needAccess=true
Schrödinger, E. (1967). What is Life? The Physical Aspect of the Living Cell. Cambridge University Press. http://strangebeautiful.com/other-texts/schrodinger-what-is-life-mind-matter-auto-sketches.pdf (Original work published 1944)
Shannon, C. E. (1948). A Mathematical Theory of Communication. Bell System Technical Journal. https://people.math.harvard.edu/~ctm/home/text/others/shannon/entropy/entropy.pdf
(2022, May 29). Information theory: Evolution as the transfer of information. Mind Matters. https://mindmatters.ai/2022/05/information-theory-evolution-as-the-transfer-of-information/