AN ASTONISHING CONCEPT: ENTROPY

Recently I went on youtube and watched a video about the most misunderstood concept in physics (linked below), and my mind was blown. That day I learned about the second law of thermodynamics and one of the most fundamental concepts in the universe: entropy. 

Entropy is mentioned quite a lot in thermodynamics, but what is it? I describe entropy as the expansion of energy throughout a system over time. This system could be a human life cycle, a mechanical engine, or the entire universe. Many people explain entropy as disorganisation, how everything has a tendency to become disorganised over time, for example: my room. I believe disorganisation is a bad word to use when describing a tricky concept like entropy, it attracts a different pictorial in the mind than what I am hoping to explain, so let’s focus instead on the word expansion. 

Let’s go back to when we were learning about the three fundamental states of matter (there’s four, but that’s better left for another day), how particles in a solid stay in formation, particles in a liquid are in less formation, and particles in a gas go wherever they want. And we also learnt about how these states change, through evaporation, condensation, and solidification. There are two terms to focus on with entropy; high entropy and low entropy. If entropy is the expansion and dispersion of energy over time, then the evaporation of a liquid is an awesome example of the concept. As a liquid evaporates into gas-like vapour, its entropy increases, going from having low entropy to high entropy. These terms describe the current expansion of the energy. In comparison to gas, a liquid like water has low entropy because its atoms and energy is contained and not freely spread out, but when evaporating, this energy expands as the water turns from liquid to gas, and spreads out into the atmosphere. This comparison of how expanded (or disorganised) the energy is in one system to another system is the difference between low entropy and high entropy. 

But entropy is not just a concept that is applied to the conversion of liquid to gas, it is applied to everything that contains energy. The second law of thermodynamics states: For a spontaneous process, the entropy of the universe increases. What does this mean? That entropy has a very natural tendency to constantly increase in systems, if low entropy is introduced, it soon disperses into high entropy. To envision this on a larger scale, I’ll introduce our local star, the Sun, and our lovely blue rock, the Earth, to one another. 

The Sun is full of energy, whether it be electromagnetic, heat, or light energy, it has enough to provide a constant stream of energy to the planet, in packets of low entropy. To explain this further, this packet of low entropy is a wavelength of light along the electromagnetic spectrum brimming with condensed energy. It has low entropy not because it has low energy, but because the energy is so tightly packed together. Let’s follow this packet full of low entropy energy, and watch it prove the second law of thermodynamics, eventually increasing its entropy and dispersing energy.

**Please note that this energy is both theoretical and real, do not envision it as a measure of watts but by an undefined concept that is found everywhere in the universe. It is a constant theoretical until applied specifically, eg. Mechanics.

Some of this energy sent over millions of kilometers from the sun is used by a budding bush of blackberries to photosynthesise. This energy is stored, and then used to grow black berries which contain smaller parts of the energy. These berries are eaten by a young deer, providing it with the same energy, as well as nutrients and a tasty treat. Eventually, the deer grows and is hunted down by a wolf, which involves the same transfer of energy. The wolf dies shortly after, and over time, its body decomposes, to which the forest floor receives its energy. This energy is spread vastly underground, to root systems and mycelium. Can you spot the moment low entropy turned into high entropy? There is none, as the expansion of energy is in increments overtime, this is not true for some things, only for most. This example is to showcase that entropy does not follow a direct line, but is rather dispersed in many different ways, constantly increasing. While the wolf was chasing the deer, they both had high entropy, as exercising disperses energy through heat. 

In summary, entropy is a very difficult subject to tackle, the explanations I have given you are just the tip of the iceberg, so to say. Many students are taught to see entropy as the increase in the disorganisation of a system, but I see it as the flow of energy, increasingly expanding over time with the universe. I advise you to understand and learn it your own way, and seek many different explanations to conceptualise it better. 

I am not an accomplished blogger, sometimes the way I write and explain scientific concepts can be very difficult to understand as I tend to imagine things in weird ways. If you are still confused about entropy, I severely recommend watching the same video I did as I have linked it to this post, and doing your own research. 

Want to understand entropy in an easy and unique way? This video explains entropy in a way that goes above physics, and beyond to everything in life.