Energy is the most fundamental magnitude in Physics. The currently most accurate low-level theory of the Universe, the Standard Model, describes everything that exists as energy stored in perturbations of quantum fields, the energy that is constantly being exchanged through the perpetual interaction between them. In natural units, used in theoretical physics, all other magnitudes (mass, momentum, potential, action, etc) are measured in units of energy, as they are nothing but different forms in which it can be stored. Furthermore, all of us encounter the concept of energy in our everyday lives and have a more or less intuitive understanding of what it is: energy is what every device around us needs in order to work, obtaining it from electric current or the combustion of fuel; and obviously, a clock uses less energy than a computer, which itself uses less energy than a plane, because it “does less stuff”. And despite all this (or maybe precisely because of this), energy is without a doubt the physical concept which most tenaciously evades a concrete and rigorous definition, and the advances in the physical sciences have constantly revealed new aspects and nuances regarding energy. Its etymological root is the Greek word ενέργεια, invented by Aristotle to refer to the realization of a potentiality (although even in the Aristotelian corpus it is hard to determine the exact meaning given to this word); but the physical magnitude known today as energy first appears in the 18th century, when the study of Newtonian mechanics led to the concept of vis viva, known today as kinetic energy (the energy a body has due to its movement). It is not until the 19th century when the new disciplines of thermodynamics and theoretical mechanics developed the modern understanding of energy, recognizing for the first time that heat, kinetic energy and potential energy are just different forms of this one quantity in constant transformation; and at the same time, the elusive nature of energy started to show itself.
Thermodynamics is the branch of physics concerned with the study of the exchange of energy and its effects on matter; but it is of a peculiar character: while most of them were developed from a merely academic and formal interest in nature (frequently by members of the nobility looking for an intellectual endeavour to spend their time in), thermodynamics was born as a practical and industrial discipline: it was around the end of the 18th century and the beginning of the 19th when, in the context of the industrial revolution, engineers like James Watt or Sadi Carnot first developed the theory of the exchange and transformation of energy in their study and design of more efficient steam engines; a theory that in the following decades would be widely expanded and integrated inside of physics by figures such as Joules, Kelvin and Clausius. Thermodynamics was the first branch of physics to attempt to describe not the divine (celestial bodies in space) but the human (machines and work). It is not a coincidence then that the categories born with thermodynamics have a remarkably human nature, for example, mechanical work and power as a physical measurement of the work (in the usual sense of the word) provided by a machine, or the distinction between free and bound energy as the energy useful or not useful to people. In fact, thermodynamics is even incapable of defining the concept of energy itself beyond the intuitive notion of “what systems need to do stuff” previously mentioned. To a certain degree, everyone born under an industrial society knows about energy as much as a physicist does (or even more).
To put this idea in more elegant words, we can say that energy is the ability to produce change, because for a system to evolve and not stay in a stationary state energy must be exchanged, be it between its different parts or with the outside (this illustrates the close relationship between energy and time, confirmed by the mathematical conjugation relationship they satisfy in mechanics). Thus, as it deals with the exchange of energy, thermodynamics can be understood as the study of the passing of time. The laws of thermodynamics, in essence, are nothing but restrictions to the kinds of changes and transformations that can occur in the Universe. Two of these restrictions, the fundamental laws of thermodynamics, stand out from the rest. The first of them is the principle of matter and energy conservation: matter and energy can’t be created nor destroyed, but only exchanged and transformed (it is interesting to note that Einstein’s famous equivalence between matter and energy is of no importance at all at human scales, even when dealing with nuclear reactions it is just a technicality). This law has been scientifically proven, because as far as we know we have yet to find a system where it does not hold; but it is also almost metaphysically self-evident: if one could create energy from nothing every possible change could be realized in a finite amount of space and time, which would have horrible consequences. Additionally, the second law states that in a closed system (one isolated from the outside world) entropy always increases with time. This leads us to consider the concept of entropy, the other great elusive magnitude in thermodynamics.
The definition and true nature of entropy has been and still is debated, in the same way as energy’s is. During the past century and a half, numerous definitions for entropy have been stated and it has been identified with all kinds of phenomena: it can be defined in terms of heat, combinatorics, uncertainty or even information. However, the intuitive notion underlying all of them (and this intuitive notion is, again, the most we can aspire to) is a measurement of how “disordered” or “useless” a system of energy and matter is. For instance, let’s suppose that we have an ice cube and a glass of hot water separately, and we put the ice cube inside the glass. The heat of the water will melt the ice and the cold of the ice will cool down the water, until we are left with just a glass of lukewarm water. The amount of energy and matter is the same in both situations (the glass of hot water and the ice cube separately in the beginning, and the glass of warm water in the end), as the water that now is inside the glass is the one there was before plus the molten ice cube, and the energy in form of heat stored in the glass of water has been transferred to the ice in order to melt it and raise its temperature. The difference lies in the higher entropy in the caloric sense that there is in the second situation (the second law of thermodynamics, in terms of heat, simply states that heat flows from hot to cold bodies). The first situation was in some sense more ordered, with two differentiated parts with different properties than the second one, where everything is mixed up. And it was undoubtedly more useful: we could have used the ice cube to keep a soft drink cool, and the hot water to make some tea; but by putting the ice cube inside the hot water we just ended up with a glass of warm water that is of no use for one thing or the other, and all we can do with it is throw it down the sink (warm water is not even pleasant to drink). If we want to recover the initial situation, we must cool down part of the water and heat up the other, using up the energy of a freezer and a microwave oven. So if we now include, in the physical system we are considering, these appliances together with their energy sources, so as to keep it a closed system; we will find that in the process of recovering the ice cube and the glass of hot water, the total entropy will have increased.
The fact that from ice and hot water, I can spontaneously obtain warm water without using up external energy but not the other way around, that a week after I arrange my desk it is disarranged and not more arranged, or that the furthest a signal travels the noisier it gets, all of this are consequences in one way or another of the second law of thermodynamics. The order and usefulness of a closed system always decrease. Identifying high entropy with this notion of disorder and uselessness may seem a poorly rigorous and anthropocentric reading of thermodynamics. Maybe what we consider useful and ordered, an alien would consider absurd and of no use. However, as we have stated before, thermodynamics itself is anthropocentric from its birth, and so are the terms it involves. Furthermore (and this is what makes it really interesting) this supposed “absence of rigour” hasn’t prevented thermodynamics from achieving remarkable results that have stood the test of time. Abstraction must serve human knowledge, and not vice versa, so if thermodynamics can provide proper knowledge (in terms of falsifiable empirical predictions) it accomplishes everything science can aspire to. And the fact is that, as far as we have observed, this strange notion of uselessness and disorder we call entropy is in constant increase. Maybe there really is a natural and universal notion of usefulness, or maybe natural laws are out to get us and devote themselves to making the Universe evolve in the most inconvenient way for us; but the second law of thermodynamics still is, despite its inherent anthropocentrism, a natural law.
With this accommodation of thermodynamics to human matters in mind, why not analyse the economic process in thermodynamic terms? After all, production consists of the transformation of raw materials into goods and services enjoyable by human beings; and so just like every other transformation process, it must be subject to the laws of thermodynamics. The first law, the conservation of energy and matter, implies that the energy and matter input of the production process is necessarily equal to its output. In this way, production can’t be spontaneous generation but transformation sensu stricto. The difference between input and output is thus not quantitative but qualitative: natural resources are transformed into products that, once they are consumed, leave behind only waste. And it is in this distinction between resources, products and waste, so related to their usefulness, where entropy and the second law of thermodynamics come into play.
Let’s consider, as a typical example, the production of a modern technological device such as a cell phone. Minerals from every continent travel thousands of kilometres around the world, being subject to transformations of infinite precision (the nanometric complexity of current integrated circuits has no match, not even in the natural realm) until they take their final form as a phone. Without a doubt, this cell phone is an amazingly ordered and useful structure, even more than the minerals from which it was made. It may look like we have avoided the second law of thermodynamics, but let’s stop and think for a moment: how has this transformation happened? It hasn’t been at all spontaneous, as huge amounts of energy have been spent in order to extract, transport, classify, weld and solder the minerals until they have formed the phone, and in these countless exchanges of energy a considerable amount of it will have dissipated as heat. Also, in all these processes, part of the matter will have dissipated too: the tools will have worn down some, the earth from the mine will have been tossed and dust from the minerals will have scattered through the atmosphere. Even considering we have access to inexhaustible energy sources such as the force of the wind or sunlight, it is impossible to take advantage of said energy without an intermediate transformation, mediated by a matter of some kind such as the silicon of solar panels or the blades of a windmill; matter that will degrade and dissipate as well in the process of obtaining the energy. Thus, we find that in any case the total entropy has increased, and this dissipation of energy and matter will be, necessarily, irreversible. But we have yet to analyse the fate of the greater part of the matter involved in the process, that is, that which currently forms the phone, the final product. Someone will buy it and use it for as much as a couple of years. However, even without taking obsolescence into account, eventually, all devices stop working. A small deterioration in the silicon of a chip (unavoidable precisely because of the second law of thermodynamics) is enough to make electrons not jump as they should; and what a moment ago was a marvellous product of human ingenuity and technological progress is now nothing more than a useless piece of junk. The materials that make up the phone, when they were still minerals, were in a relatively pure and ordered shape. However, they now are in a horrendous mix that, as soon as the tiniest of imperfections prevents them from being usable anymore, makes them completely useless. Recycling them will use up more energy than its production from natural resources took, and thus will result in a greater dissipation of matter and energy. So, the low entropy consumed in the production process is irrecoverable: the second law of thermodynamics is inescapable.
In the 21st century, we face an unprecedented crisis. For the first time in 12000 years of organized production, the exhaustion at a global level of the natural resources needed to maintain our current economic activity seems not only possible but almost unavoidable in the span of a lifetime. The origin of this crisis, after everything that has just been explained, is easy to elucidate: during the last 200 years, the never before seen acceleration in production has resulted in a corresponding acceleration in the rate of consumption of the low entropy provided by natural resources. And the great increase in entropy that has accumulated around us, in the form of waste, is already a tangible reality. Almost all of the fossil fuel on Earth has already been burnt up to CO2 scattered in the atmosphere or converted to microplastics filling the ocean, and thousands of kilos of precious metals are dispersed every day in landfills all over the world. This entropy generation is also inflicting incurable damage to Earth’s ecosystem (it’s altering the normal order of the planet, that is, disordering), and its social and political consequences are more and more evident every day: armed conflicts for the ownership of key natural resources multiply and climate change triggers an increasing amount of natural disasters. Europe is trying to lead pioneering work against this multifaceted crisis, with plans such as the Green Deal that pretend to “untie economic growth and resource consumption” and promote a “transition to clean energy sources”. However, it must be apparent by now why these objectives are unachievable: economic activity requires the consumption of low entropy, and entropy only increases. Every energy source contributes to the increase of entropy, be it by burning fuel or via the deterioration of the silicon in a solar panel. Recycling waste necessarily produces more entropy than it recovers. Entropy can’t be recycled, as the second law of thermodynamics forbids it, and no new technology will change this (relying on technology to fight against the scarcity of low entropy would be just like making our survival as a species rely on the invention of a faster-than-light spaceship). Recycling and transitioning to alternative energy sources without a decrease in production can only, best case scenario, slightly reduce the acceleration of low entropy consumption and postpone their depletion a century or two (and, worst case scenario, increase due to a higher reliance on advanced technologies). The fact that there is no possible substitute for the low entropy of natural resources leaves only one way out of this crisis that is consistent with the natural laws (the material reality of the Universe): putting an end to the unceasing need for productive expansion of capitalism.
It was Nicholas Georgescu-Roegen, a Romanian economist, who first studied the consequences of economic activity from a thermodynamic point of view, confronting the dominant mechanistic paradigm that ignored the role of the depletion of natural resources in production. On his work, I’ve based this article. He already identified the inseparability of production and resource consumption in the 70s, during the oil crisis. Sadly, his ideas went unnoticed enough for us to still be discussing useless solutions to problems that he was able to recognize then and forty years later have hit us right in the face. Every day it is more common to find scholars such as Serge Latouche who recognize the genius and visionary role of Georgescu-Roegen. Like Hari Seldon to the people of Trantor, Georgescu-Roegen offers us a recipe to avoid civilizational collapse: “a precept appropriate for our time, when the fight of humankind on natural resources threatens our survival as a species, is the following motto: “Love your species as you love yourself’ so that the current and next generations can fully enjoy life.”.
Manuel B. Melguizo García
BIBLIOGRAPHY
Georgescu-Roegen, N. (1996). La Ley de la Entropía y el Proceso Económico, Fundación Argentaria.
Georgescu-Roegen, N. (2021). Ensayos bioeconómicos, Catarata
Saslow W.M. (2020) “A History of Thermodynamics: The Missing Manual”, Entropy (Basel). 2020 Jan; 22(1): 77. doi: 10.3390/e22010077
Born in Jaén (Spain) and a physics student at the Universidad Autónoma de Madrid. Half idealist and half scientistic, half romantic and half enlightened, half melancholic and half phlegmatic; my purpose in life (and, in particular, in this magazine) is to unite my knowledge about mathematics and natural sciences with my passion for humanities.