Entropy in Layman's Terms

As a Layperson, I enjoy learning, but do need more visuals to understand some of the scientific concepts and jargon. How long I retain this information is another matter since I don't think of energy every day.

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As you move the same energy around and around the system, you eventually come to a point where there isn't any energy left that can be used: It's all been bled away as entropy. But that assumes a completely closed system. If we had more water entering the system, we can afford to lose some of it sticking to the sides of the vessel.

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I understand the water in the bucket analogy. Thank you

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This is why concepts of "information" or "disorder" make no sense in their regular senses: It isn't a question of "ordering" the energy. It's that it is no longer physically available to do any work. When we reduce the concept of the Second Law and entropy to the phrase, "The universe tends towards disorder," what we mean is that the energy distribution of the universe is tending toward a uniformity. You see, energy transfer depends upon variations in energy states. If everything is the same, then there can be no reaction.

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Yes, jargon tends to complicate the issue; especially when the common meaning of the word isn't used. That's why I stay out of the science arena. Religion has the same problem. Catch phrases or jargon are spoken that don't carry the common meaning.

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Back to the water concept: If you have a cube of ice and a pot of boiling water, there will be energy flow between the two if we put them into a system: However, that energy flow only happens because of the disparity in their energy states. The heat flows from the boiling water into the ice and eventually, the water hits equilibrium. When everything hits the same temperature, no more energy flow takes place. All the heat is now unavailable to do any work because there isn't anywhere for it go. That doesn't mean there isn't any energy: It's just that there is no disparity between any two places in the system and thus, there can be no transfer of any energy of any kind.

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I understand that the water eventually reaches the same temperature. I'm a little fuzzy on the energy transfer. Are you saying that energy transfer is like a balancing act? (I'm visualizing Parasomnium's Panda and Tiger) Energy is expended to melt the ice and once done no more energy is needed for that purpose. Kinda like when I'm relaxing in my chair and then grandson spills his drink on the floor. I now have to leave my relaxed position and expend energy to clean up the spill. Once done, I will go back to my relaxed position. The spill is the disparity. Once cleaned up, balance is back and I don't have to expend that energy.

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Entropy is simply energy unavailable to do work.

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IOW, "wasted" energy. Not used for the work at hand. Makes me think of my daughter as a teenager cleaning out the dishwasher. Take out a few dishes and then dance around the floor (headphones). The dancing around the floor is wasted energy.

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There are no perfect engines.

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Because there is always going to be wasted energy, right?

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There are no perfect refrigerators.

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I didn't quite understand where the wasted energy is in this one unless it is still the heat wasted in the moving process.Overall I feel I understand what you're saying. Unfortunately, if we got into a science discussion, as soon as one goes back to the jargon the visual is lost. Son Goku lost me.Thanks for the lesson. Learn something new everyday.

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The water has no more potential energy.

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In thermodynamic terms we would say that when the water was in the tank that it's potential energy to do work represented a lower entropy level, and that as the water flowed down the sluice and turned the wheel then went into the pool of water that its ability to do work was used up and its entropy increased. The water can no longer be used to drive the wheel because it is below the wheel now instead of above it.

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If I'm trying to explain something to someone outside the field, I would avoid using the jargon. I would put the jargon in parenthesis. Right now I have to go back to the opening post and refresh my memory on entropy. I understand the water wheel. It's easy. The water in the tank is available or in a position to drive the wheel (work). The water in the pool is not available or in a position to drive the wheel (work).So lower entropy means more energy available for work and higher entropy means less energy available for work.

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Concerning your example of your grandson spilling his drink, cleaning it up, then going back to your chair, that's not really equivalent to what is being explained. Let me try a different visual.

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Your example doesn't have the idea of equilibrium as the water and ice example.One thing to remember with laypeople is not to get to literal with our analogies. When we try to create an analogy or visual that helps us remember what something means, it may not be scientifically correct.I am the heat, the spill is the ice cube. The hot water is balanced (me resting in a chair) until an ice cube is thrown in (the spill occurs). Rrhain said: If you have a cube of ice and a pot of boiling water, there will be energy flow between the two if we put them into a system: However, that energy flow only happens because of the disparity in their energy states. The heat flows from the boiling water into the ice and eventually, the water hits equilibrium.In the hot water example, the hot water still contains energy, but there is no "work" to do. When the ice cube is dropped in there is "work" to do. Hence the spill thought.I understand what you're saying concerning the water wheel, but it doesn't give me the idea of balance or equilibrium. That's the one I'm trying to make sure I understand.Since entropy isn't something I say or think of every day; I would always have to go back and read the definition.Unfortunately, entropy sounds like a disease.

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The ATP (the main energy molecule in your cells) you use to stand up is forever gone. Your body must use ingested food to replace it, and the food will contain less energy than it did to start with. The mere act of sitting down does not replace that ATP. There is no machine or system you could use during the act of sitting down to replace all of the energy used in standing up (i.e. no perpetual energy machine).

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As I was explaining to Percy, don't take lay analogies so literally. I was afraid someone would do what you just did. I'm the heat, the spill is the ice cube.

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Refrigerators are another good example. They actually produce more heat than they do "cold". A refridgerator works by insulating the cold area from the heat it produces. However, overall there is an increase in heat due to the activity of the refrigerator. Hypothetically, if you opened all of the refrigerators in the world for a month it would actually heat the atmosphere, not cool it.

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So it is the heat generated that is wasted. Heat that is not available to be used for anything else.So entropy can be wasted energy or it can be unusable energy for a specific job.The hot air is wasted energy. Not reused for anything. But in the case of Percy's waterwheel, the water at the bottom is unusable energy in its present position for that specific job.

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When Rrhain mentioned an ice cube and boiling water he was giving a heat flow example of thermodynamics, where it's heat that is flowing from hotter to colder instead of water flowing from higher to lower. Heat can only flow from hotter to colder, not in the opposite direction, so heat will flow from the boiling water to the ice cube. When the ice cube and the boiling water are the same temperature then heat can no longer flow and the system is in equilibrium, just as in the water wheel example where when the water is all in the pool at the bottom of the wheel it can no longer flow and the system is in equilibrium.

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From a laypersons standpoint equilibrium is balance, not lack of movement. That's why the water wheel doesn't give me a visual of balance. At the beginning the top is full and the bottom empty, then the top is empty and the bottom is full.With the boiling water image, I can understand balance because the water eventually reaches the same temperature.From what I've learned so far, I now understand Rrhain's statement: There are many pithy sayings regarding the Second Law and entropy, but the problem with them is that they wind up being used in places where they make no sense. The reductions are accurate, but can only be understood within the concept of thermodynamics, not other areas. So if we're going to explain it in layman's terms, we have to start with making the point that entropy is a statement about energy. It isn't about "information" or "order" or "disorder."So I take it the concept of entropy was born in thermodynamics.Is the water wheel supposed to be an analogy for heat flow?

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Oh, no, the water wheel is pure thermodynamics, not an analogy. Just as the heat content of water has the potential to do work (e.g., steam pushing against and moving a piston in a steam engine), the potential energy of water in a water tank also has the potential to do work (e.g., turning a water wheel as it flows downhill).

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I would think the water wheel would be more like the bucket that Rrhain mentioned. The water not available for work is the water that stays attached to the buckets, splashes, leaks or soaked into the wood if they are wood. The water at the bottom is still available for work. It just has to be returned to the top.

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By the way, whether a clean or dirty rug is higher or lower in its potential to do work (lower or higher entropy) is probably impossible to figure out. Because of the analogies that are often used when explaining thermodynamics to laypeople, it is a common misconception that a dirty room has higher entropy than a clean room.

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See that doesn't give me a visual since a rug or room doesn't do work. They are viewed as work to be done. From my perspective that is like the ice cube. The heat has no work to do until the ice cube is dropped in.

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Perhaps this analogy will help. Try to balance a pencil on the tip. It doesn't like that position does it? It's unstable. The eraser side of the pencil has potential energy (gravity) which makes it unstable. When the pencil falls over that potential energy is converted to kinetic energy and the pencil winds up in a stable position (on its side). That is how the waterwheel system works. Water at a higher elevation is unstable. It has potential energy.

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Remember this is about layman's terms.I understand what you're saying about the pencil, but the water wheel doesn't provide that picture. I wouldn't view the water as unstable. You're using words that mean something very different to me than they do to you concerning the situation. I wouldn't view potential energy as unstable. Potential energy has positive impression to me and unstable has a negative from my perspective. The pencil is visually unstable on a sharpened tip.So with the pencil, where is the energy that is unavailable to do work?

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It is a real example of potential energy being converted to kinetic energy. This results in less total energy (potential energy + kinetic energy + work done) at the end than at the beginning. The loss of useable energy is entropy.

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So with the water wheel, you're talking about entropy concerning movement. The boiling water deals with entropy concerning heat.The visual seems to be different depending on the type of energy being discussed.

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Does that help?

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I understand why there can't be a literally perpetual motion machine. I wouldn't have considered that a possibility even before I read this thread just by looking at the world around me.So as heat moves it either does work or it is wasted (can't be used for work or no opportunity to do work). Heat that is not used for work is entropy?So from a very very simplistic view, entropy is wasted heat. I understand the waste in machines. How does the waste manifest itself in things that are not manmade or influenced by man?

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In the sense of there being a process by which energy is flowing, yes. But, we must be careful to recognize that the products of a reaction can themselves be used in another reaction. That is, the heat from the hot water can be used to melt the ice, but depending on just how much heat was used in the process, the leftover warm water might be capable of being used in another reaction.

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When we say it is "lost," we are referring to that one particular reaction.

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So energy lost in one reaction is not necessarily unusable in another reaction.

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But once the system reaches equilibrium, no more work can be extracted because there is no more flow.

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Now I understand the equilibrium part. Equilibrium means no "work" is possible.

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That's the glory of the Second Law: It doesn't matter what the engine is. Human-created engines are fairly obvious because they're big and we can directly see how energy comes in, stuff comes out, and the engine heats up. But there are other kinds of engines, too.

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For example, photosynthesis. It's a chemical engine. Two photons strike a molecule of chlorophyll and excite the electrons in it to a higher energy state.

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Understood.Why would a layperson need to understand entropy?I understand what you're saying concerning entropy on a very basic level, but what does this knowledge do for me or any layperson?