Law of Entropy Explained – Smart Energy Education

There many laws that govern humanity, but none are intriguing as the universal laws, such as the law of entropy. At the same time, the mention of thermodynamics can make many people automatically mentally check out. Yes, many people learn this at their university and understand how to measure gas or other aspects to conduct calculations within their university surroundings to pass their course and move on to the next part of their journey. But it is an essential factor in the discussion of sustainability, efficiency, and measurement of progress.

Individuals like Sadi Carnot, Rudolf Clausius, their German physicist colleagues, and other science members discussed maximum entropy, temperature, heat q, heat flows per unit, and other thermodynamic concepts.

It is important to consider if we are to move forward with energy conservation, sustainability processes and systems, and overall equilibrium. The first law of thermodynamics or the second law, or even other laws of thermodynamics, may not have seemed relevant at the time on a larger scale, but they relate to every aspect of life. From thermal equilibrium to a thermodynamic system and what it means for you, you must understand and refresh yourself on the law of thermodynamic states to understand temperature, energy, and building blocks of the universe.

Here is what you need to know about the second law of thermodynamics and why it is even more relevant as we seek to solve the pressing challenges that we face today in New York, Los Angeles, and other cities and rural towns worldwide.

The Second Law of Thermodynamics

The second law of thermodynamics states that “in all energy exchanges if no energy enters or leaves the system, the potential energy of the state will always be less than that of the initial state.”

The entropy of the universe or closed thermodynamic system only increases one of the more popular statements in the second law of thermodynamics. In the entropy of a system, we are talking about the disorder present within a system and, in essence, the various states that the isolated system could have. 

It makes sense on the face of it because of movement. For instance, if you had a closed system where molecules had to stay in a specific area and would not transfer elsewhere, you would state it has low entropy. Still, in many closed systems, various molecules move to different points within that system, increasing the level of entropy. If molecules continue to move around within an isolated system, that shows a high level of entropy. 

Further, in many cases, due to these processes increasing within an isolated system, we will note that most closed systems have irreversible processes. That is to say that the molecules, once moving to different states, will continue to move around as opposed to clustering in a specific area or staying in one shape.

The idea of the irreversible process is a critical one for entropy change in the second law. It seems that the entropy of the universe is only increasing due to its many potential states. Due to more interactions, the second law of thermodynamics states that there will be more entropy.

As you can see from merely sitting or standing there and reading these words, you are releasing heat into the universe, adding interactions, and increasing entropy. As more activity and actions occur, more friction happens, heat generates, and we end up with more irreversible process points. Remember that actions do not happen within a reversible process due to the arrow of time.

Indeed, the second law of thermodynamics is quite fascinating; it revolves around the idea of irreversibility. A core concept in thermodynamics is that natural processes are irreversible. And frequently, a high probability of natural methods to move to a stage of homogeneity or a system where it has the same properties at each point. This means that it has no variations in points across each aspect that ranges from energy, matter, and even temperature.

One can view this aspect in several fundamental ways. Many seek to view this law from the lens of the Clausius statement.

But what is the Clausius statement?

The Clausius Statement

It is a straightforward way of looking at the second law of thermodynamics. The basic principle present within this statement is that heat does not randomly or automatically move by itself from a low-temperature setting to a high-temperature setting. Remember that the crucial point here is that heat does not automatically or by default navigate from a low-temperature environment to a higher temperature environment randomly.

Or said differently, the Clausius statement notes that heat does not move randomly and quickly from a cool entity to a hot commodity.

Conversely, the heat transfer can, randomly or without impulse, go to the area of the lower temperature area. It is necessary to note that one cannot create a cooling unit that runs or acts without ongoing work input.

Here it is necessary to note that the definition of work within physics. 


Work in thermodynamics is the energy that moves from the specific system to the local area. Remember that work within physics is a type of energy; more so, it is in movement.

A general system will not have intrinsic work. Rather, remember that work in physics is an operation or procedure that occurs because of the system or it will happen on the system. It is essential to note that work within mechanical systems is the activity due to a force on a body at a certain duration or distance.

For instance, we cannot create an air conditioning unit that generates cooling and heating processes without work input. There is another way to look at the second law of thermodynamics.

Work is equal to force and displacement.

To be a bit more specific and to dive into the concept further, we need to understand pressure-volume work and how it relates to work. Pressure-volume work takes place when the volume of a system shifts to a different level. The pressure-volume work equates to the area beneath the process curve.

Scientists and engineers will also classify this as boundary work. Boundary work occurs when the mass of the object or body within the system boundary pushes a force or the pressure applied on the surface area to cause movement.

This work or boundary work takes place when the volume of the process shifts.

One can also view this in the Kelvin-Planck statement.

The Kevin Planck Statement and the Second Law

The Kevin-Planck statement notes that a system can’t obtain a certain amount of heat from a high-temperature receptacle while at the same time giving the same amount of work output. Again, the container or reservoir can obtain a certain energy level but cannot provide the same amount of work output.

This is not to say that an equivalent work to energy conversion cannot take place during heat transfer, rather than heat to a similar energy transfer in the form of work cannot take place. Further, one would find that heat engines will not have full thermal efficiency.

This is where we can notice that the aspect of entropy within the second law. The implication here is that two isolated systems in similar regions can be in a state of thermodynamic equilibrium separately but not in line with the other system. But then, when they interact with each other, they will obtain a state of mutual balance. At the same time, it is essential to note that overall entropy present within the new combined system is greater than or equal to that of the initially isolated processes.

At the same time, remember that the second law applies to reversible and irreversible systems. But remember that reversible processes are theoretical while processes that occur within this natural realm are irreversible. One notices that irreversibility is present within conduction or radiation. It is simple to see that heat moves from the warm one to the cold body spontaneously when a colder entity and hotter one come into contact.

These are the different points present that relate to the entropy of the system. But remember that when it comes to the laws of thermodynamics, the fun keeps on going. Indeed, there is much to learn when it comes to the first law of thermodynamics. When thinking about useful work, system surroundings, and automatic heat transfer, combined with the idea of total entropy, we must consider the arrow of time.

The Arrow of Time and Increase in Entropy

The concept, also known as time’s arrow, posits that particular direction of time. It is asymmetric, Eddington, a British scholar, discovered this concept concerning physics, and it is a wonderment that many still delve into today, as it is still a mystery. 

Eddington noted that one could see this if one were to observe the structure of elements that make up the world. He said that natural physical processes at the most minute (or atoms and molecules) level should occur in a fully or largely time-symmetric nature. If one noticed that time was to revert, the statements and other aspects that characterize them would hold. Further, at the larger level, we see that it is the opposite. 

Individuals would notice that time flows in one direction.

The second law ties in with entropy and the flow of time in various ways, but centrally, it shows the key aspect of the irreversible process at a macroscale. Yes, the idea of a reversible process is theoretical, but an increase in entropy is taking place at a larger level.

As time moves forward, the total entropy or disorder is increasing. Further, the delta of entropy increases or the growth rate should continue to rise as heat flows and time entropy occurs within the universe. Through the natural process of equalizing the distribution of mass, we see thermodynamic cycles and the mass distribution growth of life within the universe. This form of disorder within the thermodynamic process not only creates but destroys. It is an interesting concept because one notes how energy comes about and how energy dissipates due to constant statistical decay and disorder.

Our surroundings and the world we know as it exists today is because; 

Disorder always increases, and the flow of time in one direction, from spontaneous creation to internal combustion, to the study of this theory or this equation or that equation, the world and the surroundings that you know today exist because disorder always increases. Life, death, spontaneous activity, constant energy flow, gas, internal life formation on the planet, and the total sum of progress that led to reading these words in moderately comfortable surroundings would not be without this notion of time and its movement.