by David Illig
ENTROPY IN ACTION
Alfred Q. Addo-Yobo
23rd November, 2011
This paper attempts to explain simple everyday life situations and occurrences by means of thermodynamics through entropy. Everything in this life I believe happens for a reason and I know that different people would have many reasons for daily occurrences. For example, doctors believe that sore throat is caused by a bacterium as well as malaria caused by a plasmodium. Also physicists believe that in walking on a thin block, it is important to stretch your arms wide so as to increase your rotational inertia so as to keep you in a balanced position and many others. During my days as a high school student, it was very easy for me to go by these explanations and not doubt any of this, after all it’s their point of view as well. Having developed the love for thermodynamics especially entropy, I seeks to understand and attempt to explain most if not all occurrences in life such as the ones explained by physicists, doctors, etc. Entropy, I believe is a very powerful tool and in-depth understanding of its concepts could aid in explaining many theories of life. This paper seeks to explain most theories and happenings of life by means of thermodynamics through the understanding of the concept of entropy. So down below are examples of basic examples of events in life and their thermodynamic explanations through entropy.
2. Have you ever paused to think of why we feel very uncomfortable in hot rooms rather than in cool rooms?
This could be explained by many in different ways but from the entropy point of view, this is how it goes? Firstly, entropy is the number of ways by which energy can be distributed amongst energy levels within atoms or molecules, etc. Enrico Fermi, a famous scientist once proposed that the most stable state of any system is one that is geared towards maximum entropy. This proposition makes a lot of sense and basically means that for any system whose actions result in an ultimate increase in its entropy is classified as a stable system. Also remember that an increase in the entropy of the system results in a corresponding decrease in the entropy of the surroundings and vice versa. The very hot rooms has a very high entropy due to the presence of highly energetic molecules who are free to move about randomly to any corner knocking themselves off and transmitting energy to and fro other molecules. Now in this case, the man in the room is the system because it is the space understudy and the room in totality excluding the man is the surroundings. The high entropy of the rooms makes the room highly stable according to Enrico Fermi thus resulting in a decrease in the entropy of the system, which is the human being. This means that the human has relatively lower entropy in this case thus it’s moving towards minimum entropy and thus resulting in a less stable system which is the human. Every system would love to be stable and thus a feeling of instability results in uneasiness of the system. Comparatively in the cool rooms, the entropy of the surroundings are very low due to the low energy of the molecules and this results in a relatively higher entropy of the system which is the human being which results in a much stable system and this accounts for the comfort we humans feel in highly ventilated rooms.
3. Has a doctor told you walking is best for you and ever wondered why? Is it that the walking is good for your bones or possibly builds up the bones, but how? I am very sure that my friends from the medical point of view will have a reason for their saying that, but I would want to take it from the thermodynamic point of view. Now which of the two is best, walking frequently or rather sitting in a car very often?
When people walk very long distances, they are exposed to much larger immediate surroundings as compared to those who ride in the cars whose immediate surroundings are the interior of the cars. Now let’s get back to that wonderful proposition by Enrico Fermi which states that the most stable state of any system is one that is geared towards maximum entropy. In the car, though the immediate volume is very small, the entropy is very high due to the presence of people in the car and also due to the small size of the immediate surroundings, gaseous molecules often collide with each other increasing the degree of disorderliness in the surroundings. This result in the gaseous molecules moving about randomly thus increases their entropy. Now if the entropy of the immediate surroundings is increased, it results in a corresponding decrease in the entropy of the system which is the human in the car. Now let’s turn our attention back to the people who walk. When we walk, we expose ourselves to a much larger immediate surrounding which is the external atmosphere. Now when we walk, we work and this results in an energy loss to the surroundings and is supposed to result in high entropy of the surroundings leading to resultant low entropy for the system but the energy lost to the surroundings by the system in question is just a small fraction due to the greater volume or size of the surrounding compared to that of the car and thus relatively, there is a much lower entropy of the surroundings due to the fact that due to the large volume of the surroundings in this case there is less frequent collision between gaseous molecules compared with that in the car. This result in low entropy of the surrounding and much higher entropy of the system which is the man walking compared to the man in the car and thus the increased stability of the man walking compared to the man sitting in the car.
4. Have you ever wondered why it’s prudent or very healthy to sweep our rooms all the time? If I should ask you this question, why do you sweep your rooms morning and then evening time before you sleep, I am sure I may get answers like, oh, I feel very comfortable in rooms like that but do you really know why you feel very comfortable in those room, the answer is given down below?
The use of brooms are just like the reasons why God put the hands where they are, the basic reason, to decrease the entropy around us and the question is how? I believe that we all know the definition for entropy and also the corollary by Enrico Fermi that says that the most stable state of any system is one that tends towards maximum entropy> A dirty rooms has a very high entropy due to the presence of high volumes of dust particles and other gaseous components having enough energy to move around due to them being able to knock themselves very easily. Now when the rooms is swept, all these dust are taken away together with the gaseous components, leaving the room with a lesser volume of gaseous and dust components thus leaving the room with a low entropy. As we all know and understand, our major concern is the human in the room and thus the human becomes our system and any other thing including the rooms becomes the surroundings. A decrease in the entropy of a system results in a corresponding increase in the entropy of the surrounding and so in the dirty room excluding the human which is our surroundings, the increase in the entropy thus results in a decrease in the entropy of the system which is the human being. This results in an unstable human being according to Enrico Fermi. On the other hand, the very clean and swept room also the surrounding in this case with a very low entropy results in corresponding high entropy for the system which is the human being in this case. This results in a highly stable system according to Enrico Fermi.
5. Even God in his wisdom i consider a master of the applications of concepts of entropy by the positioning of the hands on the body and why they swing when we walk. I know that my physics brothers will have a lot to say about the stability it provides and centre of mass issues but let’s read about the impact of entropy on the positioning of the hands and the reasons why they should swing when we walk and also the reason why one may never win a race by sticking the hands very close to the sides of the body and not swinging it>
The importance of the hands is just related to the use of a broom in sweeping our homes. Initially when the hands are on the sides of the body, the area around the body being the surroundings has high entropy due to the movement of the gaseous molecules around and thus, the system being the human being would naturally tend towards low entropy. According to Enrico Fermi, any system tending towards low entropy would result in an unstable system. This accounts for the reason why in standing too long with the hands to one’s side, the body feels very tired and there’s a feeling of instability on the part of the body. But in the event where there is swinging of the arms, there is decrease in the volume of gaseous molecules around the body and thus a decrease in the entropy according to the entropy equation which states that S= kB In V2/V1 meaning that a decrease in the final volume, V2 of gaseous molecules would result in a decrease in the entropy of the area around the body. The surrounding which in this case is the area around the body, in the event of a swing in both arms results in a decrease in volume of gaseous molecules around the body and thus the production of a low entropy surrounding. The low entropy surrounding would now result in a high entropy system which is the human being. Now if the human being in the case of an arm swing has high entropy, then according to Enrico Fermi, the human being would be highly stable. This also means that the more you swing your arms the more you decrease the volume of gaseous matter around you and the more you decrease the entropy of the surrounding and thus increasing your (system)’s entropy and thus making you more stable. So i want someone to attempt to win a race by increasing the entropy of his or her surrounding that is by sticking his or her hands to the sides?
6. Have you ever wondered why birds are able to fly comfortably in the air? Or have you ever tried flying in the air and have failed so many times? This means that you are not doing something right? And the question is, what is supposed to be done right which you are failing to do, not by your own volition but by pure ignorance of basic thermodynamic principles>
From my understanding of thermodynamic principles, particularly the concept of entropy, birds will be able to fly only when they are able to decrease the entropy of their immediate surroundings. If birds could talk, the question on their lips will be, how do we decrease the entropy of our surrounding so that we can comfortably fly in the air? The answer lies in the flapping of their wings and another question will be how does the flapping of the wings aids the decrease of the entropy of their immediate surroundings. We first have to establish the fact that the object or space under study is the bird which is thus the system and any other than the system is the surrounding. Now we know from theory that the entropy is the measure of disorderliness in a system and the change in the entropy is given by S=kBInV2/V1 and thus the change in the entropy is directly proportional to the volume and thus when the volume of the gaseous molecules in the surroundings is lowered, it means the level of disorderliness is reduced and resulting in a decrease in the entropy of the surroundings. As the birds flap their wings they push gaseous molecules up and down away from their immediate surroundings that is the immediate circle around them. This action thus decreases the volume of the gaseous molecules around them, leaving the immediate surrounding much more ordered than before the flapping of the wings. The ordered nature of the immediate surroundings results in a low entropy immediate surroundings. Remember that the birds would continue to decrease the entropy of their immediate surroundings as they fly ahead. The decrease in the entropy of the immediate surroundings does not mean a decrease in the entropy of the overall surroundings. Now the low entropy of the immediate surrounding means high entropy of the system and resulting in a much stable system according to Enrico Fermi’s corollary of the second law of thermodynamics which states that the most stable state of any system is one that tends towards maximum entropy. The bird would thus feel much stable if it is able to effectively decrease the entropy of its surroundings by flapping the wings better.
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Lec 1 | MIT 5.60 Thermodynamics & Kinetics, Spring 2008