Thermodynamics is a branch of physics which deals with heat. Heat, in this context, is a means of energy transfer between two systems. Heat always flows from a higher energy system to a lower energy system until an equilibrium between the two is achieved, meaning both systems are at an equal temperature. Though this appears as possibly a small, even insignificant feature of the cosmos, heat and its effects govern huge swathes of the cosmological imagination.
Heat, as a measure of energy, has various effects beyond simple temperature changes, since as it increases and decreases in a system, so too does its pressure, volume, density, kinetic energy, specific heat capacity, and potentially its phase or state (meaning whether it exists as a solid, liquid or gas). These properties are considered the major quantifiable properties with which we can examine the behaviour and structure of systems, and the interaction with their surroundings.
In addition to the properties mentioned above, changes in temperature also have profound implications for the entropy of a system. Entropy is a key concept with a specific importance to thermodynamics and cosmology. It is a measure of the disorder of a system, used in the sense of high entropy meaning a highly disordered system.1
Entropy is mentioned in the second law of thermodynamics, which states that the total entropy of an isolated system always increases. This can be simplified and expanded into the statement that the Universe always moves from a more ordered state, to a less ordered state. In this statement, we see the importance of heat with regards to the Cosmos.
It is worth mentioning the meaning of the term ‘law’ in the context of thermodynamics. In such a context, a law is a fundamental principle, derived from observation, theory, and experimentation, shown to reliably predict the behaviour of matter and energy with an outstanding level of certainty. The second law of thermodynamics, or the certainty that the universe is always becoming more disordered, is one of the most well-established ideas in physics.
We must be careful to not muddy the water when approaching this statement, and in order to do so, it is worth being very clear about what exactly it refers to. The statement refers specifically to the total entropy of a system, over time, as defined by the quantity of heat (and other forms of energy transfer), encompassing both the internal thermal energy of the system and any external work done on or by the system. This also does not negate completely that small scale, or local processes of re-ordering can occur (known as negentropy) - only that these will be ephemeral and not contribute to the total entropy of the universe over time.
Negentropy refers to the reversing of thermodynamic disorder. Life and ecosystems, as well as information technology and technological systems are said to be examples of negentropy. While the concept of negentropy is recognized in thermodynamics, it is not quantifiable in the same way as entropy. Instead, negentropy is often discussed in qualitative terms, frequently requiring disciplines outside of thermodynamics, such as biology, psychology, and information systems sciences.
The unquantifiable nature of negentropy is quite an inconvenience when trying to verify the second law of thermodynamics as it applies to the cosmological notion that the universe tends toward disorder, since it essentially negates the ability to compute the balance between entropy and its opposite. In order to explore this idea, it is first important to consider some of the major contributions of thermodynamics to the understanding of the cosmos at the largest scale.
The discussion will become highly speculative, and it is important that I make it clear I have no intention to undermine the validity or erudition of thermodynamic theories; on the contrary, I have the utmost respect for it, and wish to stay as close to the scientific consensus as would be deserved by the evidence. That said, on close inspection of this body of knowledge, its fringes contain interesting uncertainties in which my imagination finds fuel for its fire, and it is the products of these fires which I will here entertain.
Let us start by recognising that our current picture of the universe is of something unimaginably vast. Its age is estimated at 13 billion years. Its dimensions approach the infinite, and its contents - stars, planets, galaxies, etc - so numerous that an almost limitless range of unknowns is considered probable.
The dimensions of the observable universe are essentially thermodynamic. Following the theory of special relativity, we define our universe in terms of the speed of light. This will be explained in detail later, but for now let it be simply stated that according to cosmology, the volume of the universe, all that there is and ever could be, is a thermodynamic hypothetical, defined by special relativity.
This vast and ancient cosmos is understood by physics to be at the mercy of entropy. Thermodynamics is its telos - or at least one of the biggest and most certain of them.
We should all know of the origins of the universe according to the scientific evidence by now; approximately 13.8 billion years ago, an extremely hot and dense plasma came into being containing all the matter and energy in our current universe, mutating into a habitable cosmos during its cooling and expanding over aeons. As space itself expanded, early stars and galaxies were able to create the natural forges in which the building blocks of life could emerge. As this process unfolded over the aeons, ever more complex structures came into being; heavier elements gave rise to the essential ingredients of organic chemistry, and planets and stars gave these ingredients the space in which to organise into living things. This understanding is supported by a wealth of observational data, including measurements of the cosmic microwave background radiation, the redshift of distant galaxies, and what we observe during distant supernovae.
In what seems to be a paradox, the evidence asserts that the early, hot universe is considered to have been a time of low entropy, with matter and radiation being highly ordered and available for work due to their uniform and symmetrical distribution throughout the universe. Evidence for this notion is presented in the uniformity of the ambient temperature of the universe, the consistent values of the redshift of distant galaxies, and the success of cosmological models such as ΛCDM, which take a low-entropy universe as its starting point and consequently display a strong correlation to the observable universe.
As time moved on, the dissipating heat, decline in homogeneity, and increase in randomness (as illustrated by the distribution of matter as galaxies, etc.) demonstrates an increase in entropy. At this most macrocosmic scale, we see nothing but a confirmation of the second law of thermodynamics in quantifiable terms. This is reflected in microcosmic thermodynamic systems when investigated by scientists, giving a complete picture of the tendency for all things to increase in entropy over time.
We can surmise then, in light of this overwhelming evidence, that if the second law of thermodynamics is infallible, then it implies that at some point in the future, a state of maximum quantifiable disorder will be certain. This is known as the ‘heat death of the universe’; a state of complete disorder, characterised by absolute randomness and an inability for energy to do work. According to thermodynamics this is inevitable in spite of negentropy, since negentropic processes are temporal, ephemeral, and localised, contributing nothing to the total entropy of the universe over infinite time spans.
This is one possible end to it all, one possible but certain telos if some other does not extinguish the universe first. This prediction comes as a consequence of the principles of thermodynamics, themselves founded upon the reliable theories which govern the concrete, exhaustively quantifiable properties of energetic systems.
That said, we have no reliable and concrete quantity representing negentropy, despite its being recognised as a real phenomena. As far as I am concerned, this presents real trouble to such a totalising concept of an inevitable cosmic heat death. To examine the difficulty posed by this missing quantity, I would like to introduce some simple deductive logic.
I will begin with an oversimplified example. For this example, assume no prior knowledge of entropy exists.
- Entropy, given time, leads to complete disorder.
- The opposite of entropy is negentropy. Negentropy, given time, leads to complete order.
- Entropy and negentropy, being opposites, negate each other.
- Therefore, if it is impossible to quantify negentropy, it is impossible to determine the total amount of entropy in the universe.
Given these premises, if we cannot quantify negentropy, it means we lack a way to measure or account for the opposing force to entropy, and therefore cannot accurately determine its net effect - we cannot fully assess the extent to which negentropy offsets entropy.
Let's be crude about it for a moment. We have a theory. Observation backs up the theory. However, we have no way to measure the opposite action, therefore, we knowingly base our theory on one half of the data. We say ‘all systems tend toward disorder, unless they don't; when they don't, we assume their effect to be negligible because we can’t measure it’. It should come as no surprise that if you measure one thing and not the other, all the evidence supports the idea that the thing you are measuring is all that matters.
It is important to reiterate that this deductive logic only works if we assume no prior knowledge of thermodynamics. Entropy and negentropy do not negate each other in a mathematical manner. The reason for this, according to the second law, is that increasing entropy is the natural tendency of all systems. Though pockets of negentropy take place on a small scale, the second law states that this negentropic system, this ordered state, will succumb to the process of disordering if given enough time.
While entropy is the natural tendency of all thermodynamic systems, negentropy is dependent on external energy being introduced to a system. For this reason, the established view is that negentropy, or ordering, can only occur because of the entropy, or disordering, of some other system.
That said, without a quantifiable measure of negentropy, it seems rash to assume the second law applies universally; that is to the universe in its totality. Though the universe is observable in its cosmic aspect, much of it remains obscure. The following ideas taint my picture of cosmic thermodynamics, and furthermore, seem unlikely to be made available for scientific scrutiny. First is that, though regional, negentropic systems may be commonplace, and increasing in number through the aeons. They, too, are lacking in the conceptual elegance which is necessary for sciences like thermodynamics to propose fundamental principles which actually function in theory and practice, and therefore evade science. The order of a living creature or information system is so vastly different to the ‘low-entropy order’ of the early universe, and end feeling as though we are comparing apples and pears, exacerbated by their complete lack of quantifiable properties.
The success of thermodynamics is to be found in its ability to predict and describe the behaviour of things. This success is entirely based on our having identified and quantified the properties of thermodynamic systems. However, without the ability to quantify negentropic systems, we lack the full picture.
When translating ‘entropy’ into ‘a capacity for energy to be made available for work’, we arrive at an interesting new framing of the problem of cosmic thermodynamics. Instead of looking at the changing amount of disorder in the universe, we might look at the changing amount of potential work.2 Unlike entropy, which can be quantified in terms of heat, pressure, or volume, the quantification of potential work requires a comprehensive understanding of the energy distribution, types of energy, and their conversion efficiencies across the entire universe. The concept of a total amount of potential work in the universe extends beyond thermodynamic considerations. The increasing complexity of the universe introduces a great deal of alternative channels for the ‘availability of energy to do work’, being influenced by gravitational interactions, electromagnetic forces, and quantum phenomena, each with its own set of complexities. Again, it is clear that any teleological assumptions we might draw from science are premature until these more complex tasks are acknowledged as having major implications for ideas of our cosmic evolution.
Is the second law to be considered truly scientific if we avoid the problem of agency, too? By this I mean that, are all systems either products of either thermodynamics or localized negentropy? If we take the universe as a whole, it seems unlikely that our picture of the forces which shape it are exhaustive. Leibniz allegedly once said ‘God played the perfect Billiards shot’. By this he is referring to the belief in the universe as a closed system, acted upon only by its initial conditions. This statement glimmers with sarcasm, though, pointing toward the unlikeliness that matter and energy simply freewheeled its way across 13 billion years of increasing entropy with no further input.
Let's go back to this idea of the universe being defined by thermodynamics. Let's also remember that I am speaking in the most conservative cosmological, that is, scientific terms. According to these terms, the dimensions of the observable universe are essentially thermodynamic. The reason for this is due to the nature of electromagnetic energy, or light, which represents the speed limit of the cosmos. At the moment of creation the boundaries of the universe began expanding at the speed of light. Not all things uniformly expanded at the speed of light; if they did, we would all be at the edge of the cosmos, traveling at the speed of light. But like a star, with rays cast in all directions, the energy moved from its source outward in all directions. This energy is the boundary of our universe, meaning what can be considered part of this Big Bang event; nothing can conceivably be outside this boundary, unless it had expanded at this speed or faster. Since nothing can travel faster than this, since the law of the conservation of energy asserts no new energy can be created, and since we see no evidence for any other source of energy, matter, or information, the universe must be an isolated thermodynamic system, expanding unobstructed at the speed of light in all directions. The first and second laws of thermodynamics, the theory of special relativity, and astronomical observations give a clear and more-or-less quantifiable sense of the dimensions of the universe, and define it as essentially reducible to thermodynamics.
The above definition can be called a thermodynamic abstraction. It is a construction, built from logical deductions and reliable facts. It is not a reliable fact itself; it is a hypothetical object which can be deduced from reliable facts. Naturally, observing and quantifying cosmic origins is not such an achievable goal as it is with isolated thermodynamic events. More to the point, with no measure of negentropy, it is left out of this cosmic picture all together.
1 It is also often defined as the unavailability to do work. This means that a high entropy system is one in which energy is unavailable for mechanical energy transfer.
2 In the context of physics, when we speak of work, we mean a transfer of energy which takes the path of mechanical motion.