When James Clerk Maxwell proposed the second law of thermodynamics, he envisioned a thought experiment in which two chambers of gas were joined by a small door under the control of a ‘demon’ who would selectively open the door depending on which direction the gas molecules were moving. If we think of the two chambers as containing mixtures of blue and red molecules, and they were randomly flitting about, the demon would open the door just as a red molecule was about to move into the right chamber or a blue molecule was about to move into the left. The door would remain closed otherwise. If such a demon were possible, Maxwell claimed, then it would be possible to convert disorder (i.e. the mixture of blue and red molecules) to order (the separation of blue and red molecules). Subsequently, however, it was felt that such a demon would itself create more disorder in the process of creating order, so, even if it existed, the second law of thermodynamics would not be violated. This post explores the assumptions underlying the second law of thermodynamics and challenges them.
Table of Contents
A Living Cell
You could replace the two chambers in Maxwell’s thought experiment with a cell and its environment. The cell boundary is known to ingest useful material—e.g. food—and excrete the waste. The cell wall is porous, but its pores have the shape and form to allow useful stuff to enter and useless stuff to go out. Somehow the cell wall recognizes what is useful and what is useless. There is no demon who opens the gates to the cell because the cell wall itself can recognize whether a molecule is useful or harmful, and selectively opens or closes the doors. The cell’s ability for pattern recognition is interesting, but to then recognize whether the alien (molecule, such as food or poison) is useful or harmful is a whole other level of complexity.
The mechanism for this ingress and egress of molecules involves proteins in the cell wall which undergo conformational change—i.e. they change form to bind to the food or waste—and transport it inside or outside the cell whereupon they are released. A conformational change is reversible; it is the molecule rearranging its structure to bind to the food or waste, and then rearranging itself to its original state. Since the process is reversible, it doesn’t violate the second law of thermodynamics. And yet it produces order from disorder (e.g. by excreting the harmful waste and ingesting the useful food).
The cell wall replaces Maxwell’s demon which needed a mind-brain to recognize, a hand to open or close the door between the chambers and have the evil intention to break nature’s law. One could suppose that this demon consumed energy and in the process of creating the order would produce a greater amount of disorder. But what if there is no demon? What if the boundary itself intelligent enough to open and close the doors selectively? And the process remains reversible? Cell wall molecules undergo such reversible conformational changes.
The Distribution of Energy
To understand this problem a little better, we need to delve a little bit into physics. The laws of physics prescribe that the total energy is conserved, but they don’t fix the distribution of energy. The same total matter and energy could therefore be distributed differently, without violating physical laws.
In classical mechanics, the initial state from which the system evolves is an assumption. The conservation laws of physics allow for many other states. So, why the system is in a specific initial state cannot be explained. If, however, you assume the existence of such a state, then you could solve the equations of motion to predict the current state. If that assumption is disallowed, then no predictions are possible.
In statistical mechanics, it is impossible to determine this initial state, so it is assumed that the system is potentially in all possible states. Indeed, the measure of disorder in the system is the total number of possible states, subject to the following conditions—(a) the total energy is constant, (b) the total number of particles is constant, and (c) the total volume of the system is constant. In short, underlying statistical mechanics—which rationalizes thermodynamics on a mechanical thesis—is the recognition that the system can be in one of the many possible states. If the total number of possible states isn’t increasing or decreasing, the entropy is supposed to be constant.
In quantum theory too, the state of a system is described by a wavefunction, and the possible states of this wavefunction constitute its entropy. A wavefunction with only two states, therefore, has lower entropy than the wavefunction with hundred states. A wavefunction can also be expressed through many bases each of which represents a different distribution of matter. Each such basis is selected by a measurement apparatus. For instance, in the slit experiment, two slits select one basis and three slits select another basis. Since each basis can have a different number of states, therefore, the entropy of the system can increase or decrease just by changing the number of slits. This is even more perplexing because in this case entropy changes without any physical interaction.
Returning to the main point, in every physical theory we recognize that there are many possible distributions of matter, with total energy being constant. Some of these distributions have a large entropy while others have a small entropy. The Second Law of Thermodynamics states that net entropy cannot decrease, which means that the universe must be headed toward greater entropy. This classical physical idea is already violated in quantum mechanics where you can change the number of slits in an experiment, and thereby reduce the total number of possible states in the wavefunction. The change in the number of slits in a quantum experiment is just like Maxwell’s Demon who selectively opens or closes the door; in this case, the Demon increases or decreases the number of doors, which changes the entropy. The proponent of the Second Law of Thermodynamics would say: We cannot change the number of slits without incurring some entropy increase.
However, when someone makes that claim, they are assuming that the slits are a classical system; they cannot rearrange themselves except through an external force, and that external force requires transfer of energy, which will then cause entropy increase. This assumption is false for a quantum system. A quantum system can indeed rearrange itself without an external force, which is called a conformational change. Such conformational changes can be triggered without an exchange of energy with the environment. The cell wall involves such conformational changes in which the proteins of the wall rearrange their structure, and that rearrangement is effectively like a door that opens or closes.
The question is: Why does the cell wall rearrange itself based on the presence of certain molecules in the environment? The conformational change is not random after all. Since it is triggered by something in the environment, that environment must be its cause. However, that cause need not involve a classical energy exchange. We can also think of the environment as the slits which rearrange the quantum system of the wall. In short, we can produce a cascading system of slits layered on top of each other and the environment becomes the slits for the cell wall, the cell wall is the slits for what is inside the cell, and so on. By this cascading arrangement of slits, the cell wall can rearrange itself without a transfer of energy from the environment. And that rearrangement can be called the “recognition” of the environment.
Thus, we can think of the cell wall as a collection of potentials, such as open and shut gates. The environment selects one such potential and causes the gate to open or close, notably, without an energy transfer. In this arrangement, the cell inside, the cell wall, and the cell environment are all quantum systems. However, they operate in three different modes: the cell environment acts as the slits to rearrange the cell wall, and then the cell wall acts as the slits to permit or deny the entry of the environment. The question now is simply this: How can the cell wall alternately behave as a quantum system, then as the slits, and then as the environment? It a change of mode, but what causes it?
The Role of Time
We don’t know the answer to this question in current science, but we can if we treat time causally. There is nothing that stops us from treating the cell wall as a quantum system, then as slits, and then as the environment; all three interpretations are possible. And by that change in the modality of the same thing, it will behave differently, and that would in turn create order. And this is possible if we say that time cycles the same thing through three alternating modes. In short, sometimes the cell wall is a quantum system, and then it is the slits, and then it is the environment. The change of modalities of the cell wall is caused by time, and they are cyclical. That cyclical change in the modes of the cell wall pulls in food and pushes out the waste. So, the wall seems to do things because time changes its modality.
Things will stop working if time stopped changing the modalities. Therefore, time’s role in changing the modality is paramount. Now, you could also say that time is linearly moving forward, but its effect is cyclical because it transforms the same thing into different modes.
Linear and Cyclic Time
Imagine you were walking along a circular path, and you could only walk forward. If you took steps from A to B, and you could not go back, you could assert that the process is irreversible. But is it truly irreversible? You could keep walking around the same path and you will arrive at the original place because the path is circular. You haven’t retraced the steps, and you have still produced the same effect of retracing. Yes, while walking on a circular path, you cannot retrace your steps. So, the arrow of time holds. But you can still get back to the place where you started, in violation of the second law. If you want to uphold the Second Law, you must insist that time is not cyclical; it must be linear.
If time were cyclic, there would be no difference between reversible and irreversible processes. The reversible processes would just have a shorter cycle time, and the irreversible processes would have a longer cycle time; they would just seem to be irreversible on shorter measurable scales.
Does it mean that the milk that has been spilled on the floor will automatically get back into the bottle? Certainly not—you cannot retrace the steps. But it does mean that the milk will decay, form the food in the soil, from which grass will grow, which the cows will consume, and produce another bottle of milk. Energy will redistribute, from one state to another, until it restores itself in a previous state.
If time is cyclic, then the second law of thermodynamics is only partially true—it says that time doesn’t go backward. What it doesn’t say is that change moves forward to restore its former state.
Living bodies and living ecosystems are examples of this cyclic pattern. Energy is transformed into useful products, then converted into waste, and then again converted back to useful stuff. There is a natural rhythm or pattern in which this happens. If we consume natural products faster and transform them into waste faster than nature can restore, then there will be an abundance of waste. Under this wasteful consumption, there won’t be enough left to consume, and the consumers will die. Nature will then restore itself back to the previous state—over the due course of its natural cycle.
In this cyclical change, time produces order and disorder, naturally. The idea of entropy increase is conceptually identical to a linear arrow of time. However, if time is cyclical, and it has causal properties of mode selection, then nature can seem to create order from disorder, and disorder from order. Factually, it would neither be order or disorder, because nature is simply a possibility. However, the selection of some possibilities would appear as order or disorder. That appearance hides from plain sight that nature is always ordered and sometimes we see that order and at other times we don’t. Under that view, we would recognize that the universe is not headed toward a ‘heat death’. It is rather undergoing a cyclic process of creation and destruction.