michel123456 Posted October 8, 2015 Share Posted October 8, 2015 (edited) ! Moderator Note this thread is a split from here http://www.scienceforums.net/topic/90145-thermodynamic-arrow-of-time-equating-entropy-and-disorder/ I completely disagree. The example is terribly misleading. The cup is a by-product of life, like an egg, or anything else that has been produced by a living being. And we know that living systems are self-organizing ones. Life create things that do not appear "just like that", as if Life was struggling against entropy. Let's take another example, say a melting iceberg. Of course you will not observe the sea water making back the iceberg. But the melted fresh water of the iceberg will mix with the salt water from the ocean, maybe travel until the tropics, eventually evaporate and form a cloud from which snow will fall and form a new iceberg, in a few thousand years cycle I suppose. But ultimately, yes the iceberg will form again. Simply not in the way we figure, not backwards in time. The book is also a by-product of life. You cannot use it in order to explain physics. Because if you use the living element in your answer, as you did in your question, well yes the broken cup of tea can be fixed by a human, and the pages of the book can be put in the right order again. Better analogies must be taken out of the pure world of physics. Edited October 12, 2015 by imatfaal Link to comment Share on other sites More sharing options...
Cuba Posted October 8, 2015 Share Posted October 8, 2015 The book is also a by-product of life. You cannot use it in order to explain physics. Because if you use the living element in your answer, as you did in your question, well yes the broken cup of tea can be fixed by a human, and the pages of the book can be put in the right order again. Better analogies must be taken out of the pure world of physics. Your basically saying that drawing a picture of a DNA molecule is wrong because its not exactly right? The point of an analogy is to give a basic understanding of the concept, not the precise physics. And the cup analogy is something easily pictured and shortly described. 1 Link to comment Share on other sites More sharing options...
swansont Posted October 8, 2015 Share Posted October 8, 2015 I completely disagree. The example is terribly misleading. The cup is a by-product of life, like an egg, or anything else that has been produced by a living being. And we know that living systems are self-organizing ones. Life create things that do not appear "just like that", as if Life was struggling against entropy. Let's take another example, say a melting iceberg. Of course you will not observe the sea water making back the iceberg. But the melted fresh water of the iceberg will mix with the salt water from the ocean, maybe travel until the tropics, eventually evaporate and form a cloud from which snow will fall and form a new iceberg, in a few thousand years cycle I suppose. But ultimately, yes the iceberg will form again. Simply not in the way we figure, not backwards in time. The book is also a by-product of life. You cannot use it in order to explain physics. Because if you use the living element in your answer, as you did in your question, well yes the broken cup of tea can be fixed by a human, and the pages of the book can be put in the right order again. Better analogies must be taken out of the pure world of physics. This is what we call "reading way to much into an analogy". The origin of the cup is beyond the scope of the analogy; it is to be ignored. The initial condition of the analogy is that you have a cup. That's all. Link to comment Share on other sites More sharing options...
michel123456 Posted October 9, 2015 Author Share Posted October 9, 2015 This is what we call "reading way to much into an analogy". The origin of the cup is beyond the scope of the analogy; it is to be ignored. The initial condition of the analogy is that you have a cup. That's all. I disagree. The origin of the cup is human kind. Take an analogy with a rock and you will see that rocks have been formed. You can crash it in piece, after enough time it may become a rock again. What other example to take? A star, a planet? Do they only dismantle and disappear? Or do they "create"? What other analogy or example can you find? ------------------ Or to say it otherwise: you cannot explain physics on the basis of the behaviour of a monkey. Link to comment Share on other sites More sharing options...
swansont Posted October 9, 2015 Share Posted October 9, 2015 I disagree. The origin of the cup is human kind. Take an analogy with a rock and you will see that rocks have been formed. You can crash it in piece, after enough time it may become a rock again. What other example to take? A star, a planet? Do they only dismantle and disappear? Or do they "create"? What other analogy or example can you find? What impact does the origin of the cup have on its entropy? Or the rock? How does what could happen later affect its entropy now? Or to say it otherwise: you cannot explain physics on the basis of the behaviour of a monkey. In what way do monkeys violate the laws of physics? Otherwise, what does this have to do with anything? And monkeys have been used as examples to explain physics http://www.physics.ucla.edu/demoweb/demomanual/mechanics/ballistics/monkey_and_hunter.html Link to comment Share on other sites More sharing options...
michel123456 Posted October 9, 2015 Author Share Posted October 9, 2015 What other analogy or example can you find? Link to comment Share on other sites More sharing options...
studiot Posted October 9, 2015 Share Posted October 9, 2015 What other analogy or example can you find? Example of what please? Link to comment Share on other sites More sharing options...
swansont Posted October 9, 2015 Share Posted October 9, 2015 The cup was the example of the OP. If you want to discuss something else, you can always open up a new thread. Link to comment Share on other sites More sharing options...
michel123456 Posted October 10, 2015 Author Share Posted October 10, 2015 Example of what please? An example of the thermodynamic arrow of time, equating entropy and disorder. The cup was the example of the OP. If you want to discuss something else, you can always open up a new thread. The cup was an example of Stephen Hawking that the OP cannot understand. My answer to this is that it is a bad analogy. ---------------------- And you still haven't answer my very simple question: What other analogy or example can you find? Link to comment Share on other sites More sharing options...
studiot Posted October 10, 2015 Share Posted October 10, 2015 An example of the thermodynamic arrow of time, equating entropy and disorder. Entropy can be quantified by definition, but you would need a quantifying definition of disorder, using connecting variables, to achieve an equation. Do you have one? Link to comment Share on other sites More sharing options...
michel123456 Posted October 10, 2015 Author Share Posted October 10, 2015 (edited) Entropy can be quantified by definition, but you would need a quantifying definition of disorder, using connecting variables, to achieve an equation. Do you have one? Jesuits are mastering this technique to answer a question with a question. -------------- I asked for a simple analogy. That does not involve cups of tea, milk and coffee, humans and monkeys, plants and seeds. An analogy that you take out of simple non living physical elements. Like salt dissolved in fresh water for example. Edited October 10, 2015 by michel123456 Link to comment Share on other sites More sharing options...
studiot Posted October 10, 2015 Share Posted October 10, 2015 Jesuits have this technique to answer a question with a question. You asked for an equation. I do not have a suitable definition of disorder (or order for that matter) to offer one so I did the next best thing and gave you an answer specifying the conditions (as well as I could) to obtain an equation. Link to comment Share on other sites More sharing options...
michel123456 Posted October 10, 2015 Author Share Posted October 10, 2015 I see we are not communicating very well. Let's go back to the OP. He cites the following “You may see a cup of tea fall off of a table and break into pieces on the floor. But you will never see the cup gather itself back together and jump back on the table… The increase of disorder, or entropy, is what distinguishes the past from the future.” What I say is that the cup of tea is a by-product of life. Laws of physics do not allow the presence of a cup of tea in the first place without the intervention of a living being (the human kind in this example). And I think that you cannot expect from simple physics to recreate a cup that it cannot create in the first place anyway. Now if you take a rock falling from a mountain into the sea, you may expect that the rock will not climb to the mountain back. But if you wait long enough (billion of years) you may see a mountain emerge from the sea where the original rock fell in. Because if you are thinking only about the arrow going from order to disorder, then how was the Earth created from a gas cloud? How do galaxies generate stars? How did the galaxies formed from "gas clouds" or anyway? Would that mean that the Earth, the Sun, the Solar System, the Milky Way are some forms of disorder that are the results of something more ordered? Link to comment Share on other sites More sharing options...
Sensei Posted October 10, 2015 Share Posted October 10, 2015 An analogy that you take out of simple non living physical elements. Like salt dissolved in fresh water for example. Solid state salt + addition of water from rain -> solution. Ions are (more or less) evenly spread in solution. Solution evaporates because of Sun and temperature -> when there is high concentration of salt in small amount of water, solid state crystals are starting growing. Crystals have highly organized structure. That's standard procedure of making crystals in laboratories: evaporate water below saturation point and wait. Link to comment Share on other sites More sharing options...
swansont Posted October 12, 2015 Share Posted October 12, 2015 So what is it about life that changes the entropy of an object? If I have an industrial diamond and one that was formed in the earth, and they are indistinguishable, which one has a higher entropy and why? Link to comment Share on other sites More sharing options...
michel123456 Posted October 12, 2015 Author Share Posted October 12, 2015 (edited) So what is it about life that changes the entropy of an object? If I have an industrial diamond and one that was formed in the earth, and they are indistinguishable, which one has a higher entropy and why? Tell me. My comment was not about entropy. My comment was about the correctness of the use of living things when you want to explain physics. IMHO you cannot do that. You will only get wrong results. ---------------- So that now, in Stephen Hawking's example, you can replace the broken cup of tea with a diamond. “You may see a diamond fall off of a table and break into pieces on the floor. But you will never see the diamond gather itself back together and jump back on the table… The increase of disorder, or entropy, is what distinguishes the past from the future.” The word diamond in the above replaced by me. In this example, one can say that yes, waiting long enough, you will see the diamond being recreated (that was one of the job of Mother Earth these last billion years). And No you will not see the diamond jump on the table, because even in backwards time gravitation is still attractive, from what I remember. What all of this has to do with entropy I don't know. As a side note, if the diamond breaks when falling, you should complain to the seller. And a table is also a by-product of life. Edited October 12, 2015 by michel123456 Link to comment Share on other sites More sharing options...
swansont Posted October 12, 2015 Share Posted October 12, 2015 Tell me. My comment was not about entropy. My comment was about the correctness of the use of living things when you want to explain physics. IMHO you cannot do that. You will only get wrong results. ---------------- So that now, in Stephen Hawking's example, you can replace the broken cup of tea with a diamond. The word diamond in the above replaced by me. In this example, one can say that yes, waiting long enough, you will see the diamond being recreated (that was one of the job of Mother Earth these last billion years). And No you will not see the diamond jump on the table, because even in backwards time gravitation is still attractive, from what I remember. What all of this has to do with entropy I don't know. As a side note, if the diamond breaks when falling, you should complain to the seller. And a table is also a by-product of life. The conditions of the example are that there is no outside energy put into the system; the diamond will not spontaneously reassemble. "Mother earth" and her partner in crime, the sun, represent energy input and work being done. Like I said before, you are reading too much into it. What all of this has to do with entropy I don't know. And yet you saw fit to proclaim that you cannot use living things to explain physics. If this isn't about entropy, what is it about? What about living things violates the laws of physics? Or otherwise renders them unfit to be used in an example? Link to comment Share on other sites More sharing options...
michel123456 Posted October 13, 2015 Author Share Posted October 13, 2015 (edited) The cup of tea exists in one single state. that is because a human made the cup in the first place. There was energy and intelligence put into it. What I say is that you cannot "forget" that fact. You cannot begin the analysis from the cup "as if the cup existed just like that", then break the cup and extract a safe conclusion about physics. Take sand, water, air, diamonds (uncut) and you may see that the same way the sand can be dispersed, the same way it can come together and form a rock. Break a desert rose for example. Of course the pieces will not jump together, but if you wait long enough, that may happen, the same way it happened once for the desert rose to form in the first place. Edited October 13, 2015 by michel123456 Link to comment Share on other sites More sharing options...
swansont Posted October 13, 2015 Share Posted October 13, 2015 The cup of tea exists in one single state. that is because a human made the cup in the first place. There was energy and intelligence put into it. It was a cup, not a cup of tea. What I'm asking is how you measure the effect of this intelligence in the object, in regard to physics. And why it matters, in regard to measuring a change in entropy when it breaks. Is there some special form of entropy involved, from the intelligence? What I say is that you cannot "forget" that fact. You cannot begin the analysis from the cup "as if the cup existed just like that", then break the cup and extract a safe conclusion about physics. And what I'm asking is why. Take sand, water, air, diamonds (uncut) and you may see that the same way the sand can be dispersed, the same way it can come together and form a rock. Break a desert rose for example. Of course the pieces will not jump together, but if you wait long enough, that may happen, the same way it happened once for the desert rose to form in the first place. But the example in question is excluding the process that built it in the first place — there is no further addition of energy. That's the whole point: entropy does not spontaneously decrease. Link to comment Share on other sites More sharing options...
studiot Posted October 13, 2015 Share Posted October 13, 2015 I have tried to avoid discussion about the cup because I think it is a distraction. However there are some points that need adjustment. Michel What I say is that you cannot "forget" that fact. You cannot begin the analysis from the cup "as if the cup existed just like that", then break the cup and extract a safe conclusion about physics. Actually you can and we do. That is what thermodynamics is all about. You work from (equilibrium) state A to (equilibrium) state B... to (equilibrium) state C and so on. So you can and we do start at any defined state and finish on another defined state and not worry about what comes before or after. swansont It was a cup, not a cup of tea. Actually it was a cup of tea. Sorcerer quoting Hawking “You may see a cup of tea fall off of a table and break into pieces on the floor Link to comment Share on other sites More sharing options...
michel123456 Posted October 13, 2015 Author Share Posted October 13, 2015 And what I'm asking is why. Because there exist no way for physics to make a cup without the help of a human being. Entropy increasing or decreasing, there is no way. You cannot expect physics to do things it cannot do anyway. The only way for nature to make a cup is to use a living being. And living beings can make objects by assembling things in a way that nature does not. Link to comment Share on other sites More sharing options...
studiot Posted October 13, 2015 Share Posted October 13, 2015 Because there exist no way for physics to make a cup without the help of a human being How about an acorn cup falling to the ground, becoming detached from its acorn and becoming fossilised? Did you catch my post#20? Link to comment Share on other sites More sharing options...
swansont Posted October 13, 2015 Share Posted October 13, 2015 Because there exist no way for physics to make a cup without the help of a human being. Entropy increasing or decreasing, there is no way. You cannot expect physics to do things it cannot do anyway. The only way for nature to make a cup is to use a living being. And living beings can make objects by assembling things in a way that nature does not. I'm asking why this matters. (IOW, my response is "So what?") Unless you contend that humans violate the laws of physics. We apply physics to human endeavors all the time. It's why we can drive cars, fly in airplanes and why we sent people to the moon, and robots to Mars. Link to comment Share on other sites More sharing options...
puppypower Posted October 13, 2015 Share Posted October 13, 2015 So what is it about life that changes the entropy of an object? If I have an industrial diamond and one that was formed in the earth, and they are indistinguishable, which one has a higher entropy and why? The fundamental principle of life and entropy is evident in the simple system of water and oil. If we start with water and oil, this will form two layers. If we add energy via agitation, we can increase the entropy of the system to form an emulsion. If we let the emulsion stand, without agitation, the entropy will spontaneously decrease back to two layers. This does not violate the second law of entropy because entropy is part of a larger equation connected to free energy G= H-TS, where H is enthalpy (internal energy), T is temperature K, and S is entropy. In this example, the emulsion lowers entropy because this is a way to lower the more dominate H connected to surface tension so G is minimized. There is a tendency, in discussions of entropy, to disconnect entropy from free energy and internal energy, which leads to misunderstanding. Under the special case where H=0, than G= -TS. This would make entropy free standing but this is only a special case. Closed systems do not have any change in internal energy H so this can create the more simplified special case. The interaction of water and organics, due to not always mixing, can amply the H or internal energy of living systems; membrane and water.This is maximized between water and organics and is one reason why water is so important to life. Using that source of H, entropy can be lowered into self ordering systems. For example, when protein fold, this is due to hydrophobic interactions on the protein. The protein folding is less to due to the protein wanting to bind to itself, as it is due to the need to bind to itself, because of the internal energy created by the presence of water; hydrophobic. This H is strong enough to lower the protein S into unique folds with probability equal to 1.0. Protein folding is not even subject to chance, but are extremely reliable due to H (water-organic) dominating S. When we make a cup in the factory will add H to mold it into a low S. Link to comment Share on other sites More sharing options...
studiot Posted October 13, 2015 Share Posted October 13, 2015 puppypower Closed systems do not have any change in internal energy H so this can create the more simplified special case. Another adjustment please. A closed system does not allow mass (matter) to cross its boundaries. Energy, however, may do so. An isolated system bars both mass and energy. Link to comment Share on other sites More sharing options...
Recommended Posts
Create an account or sign in to comment
You need to be a member in order to leave a comment
Create an account
Sign up for a new account in our community. It's easy!
Register a new accountSign in
Already have an account? Sign in here.
Sign In Now