MigL Posted January 13, 2013 Posted January 13, 2013 Entropy is related to the lack of USEABLE energy of a system. As an example, when a system converts all its energy to heat and comes to thermal equilibrium, no more energy is available to do work, and entropy is maximized. Thiis is commonly known as 'heat death'.
Mike Smith Cosmos Posted January 13, 2013 Posted January 13, 2013 (edited) Entropy is related to the lack of USEABLE energy of a system. As an example, when a system converts all its energy to heat and comes to thermal equilibrium, no more energy is available to do work, and entropy is maximized. Thiis is commonly known as 'heat death'. When a lot of hydrogen has converted to deuterium , then doubled to helium, surely useable energy is available all the way up to IRON , where the binding energy graph peaks. Then the star collapses and goes either super nova or red giant depending on its mass compared to our sun. ( Much more Supernova, same or less Red giant ) What I don't know, is if one was representing ENTROPY graphically say in the way that three dimensional space -time can be represented as a 3D lattice with distortions near heavy objects. Whether an Entropy 3D lattice would look like a elongated rectangular cubic form , running in time from left to right , uniformly the grid intensifying as one moved right (forward in time).{ general increase in entropy as the universe ages and cools} BUT when examining the 3D grid closely , one would see small regions where the density of the grid changed to more spread out showing regional lowering of entropy around say nuclear fusion, molecular construction, maybe even life forms ? Yet still generally an increase of entropy as the universe ages and Cools. What say you ? . Edited January 13, 2013 by Mike Smith Cosmos
MigL Posted January 16, 2013 Posted January 16, 2013 The useable energy doesn' t peak when the core becomes iron. At that point there is no more energy left to liberate via the fusion process and the star is overcome by its gravity. The subsequent collapse and 'bounce' lead to the violent stellar explosions, but this energy is provided by the gravitational field. Not fusion. I'll repeat, unless we consider degrees of freedom, order and disorder are subjective and not quantifiable, so I hesitate to use that definition of entropy.
Mike Smith Cosmos Posted January 17, 2013 Posted January 17, 2013 (edited) The useable energy doesn' t peak when the core becomes iron. At that point there is no more energy left to liberate via the fusion process and the star is overcome by its gravity. The subsequent collapse and 'bounce' lead to the violent stellar explosions, but this energy is provided by the gravitational field. Not fusion. I'll repeat, unless we consider degrees of freedom, order and disorder are subjective and not quantifiable, so I hesitate to use that definition of entropy. Surely in chemistry , where elements are combining so as to become molecules and compounds. The degrees of freedom are much reduces from freely moving anywhere, to moving only in the direction of molecule and compound production. A similar argument , I would have thought could be argued for nuclear fusion, Rather than atoms, or particles being free to diffuse in multi degrees of freedom , rather combination of particles , right up through the life chain , demonstrates less degrees of freedom , following convergence , thus following a decreasing entropy. Edited January 17, 2013 by Mike Smith Cosmos
ACG52 Posted January 18, 2013 Posted January 18, 2013 I don't think it does. Thermodynamics tells us that from this point forward in time, entropy should increase. But it also tells us that from this point backwards in time, entropy should have been higher. While entropy always increases, it does so in both time directions, so there's no real reason that entropy was lower in the past.
Mike Smith Cosmos Posted January 18, 2013 Posted January 18, 2013 I don't think it does. Thermodynamics tells us that from this point forward in time, entropy should increase. But it also tells us that from this point backwards in time, entropy should have been higher. While entropy always increases, it does so in both time directions, so there's no real reason that entropy was lower in the past. I am not so convinced this is the end of the matter. I am not convinced Entropy always increases. Yes in a lot of circumstances the degrees of freedom increase or are more, and yes in those circumstances, yes heat flows away in a thousand directions, china gets smashed into a 1000 pieces and energy flows out the window and through the walls and we face large energy bills. But there is a light on the horizon: nuclear fusion happens, life comes into being, molecules and compounds are sticking together all the time, stars form from dust and molecular clouds, planets appear in accretion rings, the universe is being made before our very eyes. If there is not some order out of chaos going on in a decreasing entropy form , somewhere among that lot "I'll eat my hat. "
ACG52 Posted January 19, 2013 Posted January 19, 2013 I am not so convinced this is the end of the matter. I am not convinced Entropy always increases. Yes in a lot of circumstances the degrees of freedom increase or are more, and yes in those circumstances, yes heat flows away in a thousand directions, china gets smashed into a 1000 pieces and energy flows out the window and through the walls and we face large energy bills. But there is a light on the horizon: nuclear fusion happens, life comes into being, molecules and compounds are sticking together all the time, stars form from dust and molecular clouds, planets appear in accretion rings, the universe is being made before our very eyes. If there is not some order out of chaos going on in a decreasing entropy form , somewhere among that lot "I'll eat my hat. " But when you look at the entire closed system (i.e. the universe) entropy always increases. Locally, entropy might, and does, decrease, but you must consider the entire system.
Mike Smith Cosmos Posted January 19, 2013 Posted January 19, 2013 (edited) But when you look at the entire closed system (i.e. the universe) entropy always increases. Locally, entropy might, and does, decrease, but you must consider the entire system. Yes, that is fine, and can see or experience the universe moving in the main flow direction of increased entropy. However if some local areas have a flow to decreased entropy , then that is interesting in relation to energy flow, states of order, and ? possibly local time ? Edited January 19, 2013 by Mike Smith Cosmos
eytan_il Posted January 19, 2013 Posted January 19, 2013 (edited) I've heard many physicists put forward the second law of thermodynamics as an explanation of the vector of time. Can someone explain to me why that is not circular reasoning? It seems that it merely says that entropy increases with time therefore time must increase with entropy. How is that not circular? Isn't a better proposal needed for an explanation? Yes it does, Entropy is some sort of statistical memory of spacetime and matter. In big words it means "mess" always grows in Thermodynamic systems. For the last 10 years I've been working exactly on your question. Yes, we can say time grows with entropy because we can define a field of time !!! From each event we can connect a curve to the "big bang" such that the proper time it measures along it will be maximal. On ordinary geodesic curves on the Lorentzian manifold of spacetime, only local maximum of proper time is measured. The field of time is absolute maximal time. As such, it defines a scalar field on the manifold of spacetime. This scalar field has a gradient. Where there is matter, more than one such curves of absolute maximum proper time intersect and the gradient becomes discontiuous. Spacetime resolves the discontiuity by quantum uncertainty. A limit to the quantum theory is a classical one which I also worked on. The theory uses tensors but is so simple and so revolutionary that I find it very difficult to publish though there is a physics professor who likes the idea. Currently I try to publish the theory in the Canadian Journal of Physics which is expected to reject the paper and not due to professional reasons. If they accept the paper I will have to delete the following link: http://he.scribd.com/doc/62076298/Emergent-Time The theory not only explains that spacetime has memory in the form of scalar field but also shows how the field is defined by matter which is simply a geodesical conflict in spacetime. Entropy is simply a result of motion of singularities of the gradient of the time field. The theroy also discusses Dark Matter and Dark Energy as well as ordinary matter as 3 solutions of one equation. Edited January 19, 2013 by eytan_il
Mike Smith Cosmos Posted January 19, 2013 Posted January 19, 2013 Yes it does, Entropy is some sort of statistical memory of spacetime and matter. In big words it means "mess" always grows in Thermodynamic systems. For the last 10 years I've been working exactly on your question. Yes, we can say time grows with entropy because we can define a field of time !!! From each event we can connect a curve to the "big bang" such that the proper time it measures along it will be maximal. On ordinary geodesic curves on the Lorentzian manifold of spacetime, only local maximum of proper time is measured. The field of time is absolute maximal time. As such, it defines a scalar field on the manifold of spacetime. This scalar field has a gradient. Where there is matter, more than one such curves of absolute maximum proper time intersect and the gradient becomes discontiuous. Spacetime resolves the discontiuity by quantum uncertainty. A limit to the quantum theory is a classical one which I also worked on. The theory uses tensors but is so simple and so revolutionary that I find it very difficult to publish though there is a physics professor who likes the idea. Currently I try to publish the theory in the Canadian Journal of Physics which is expected to reject the paper and not due to professional reasons. If they accept the paper I will have to delete the following link: http://he.scribd.com/doc/62076298/Emergent-Time The theory not only explains that spacetime has memory in the form of scalar field but also shows how the field is defined by matter which is simply a geodesical conflict in spacetime. Entropy is simply a result of motion of singularities of the gradient of the time field. The theroy also discusses Dark Matter and Dark Energy as well as ordinary matter as 3 solutions of one equation. Wow! I need to digest this.
michel123456 Posted January 19, 2013 Posted January 19, 2013 I don't think it does. Thermodynamics tells us that from this point forward in time, entropy should increase. But it also tells us that from this point backwards in time, entropy should have been higher. While entropy always increases, it does so in both time directions, so there's no real reason that entropy was lower in the past. I don't understand that.
ACG52 Posted January 19, 2013 Posted January 19, 2013 I don't understand that. The second law of thermodynamics says that from any point in time, entropy increases toward the future. But the law of physics are time invarient, that is, they treat forward and backward in time the same. Therefore this implies that entropy should increase in the direction of the past, as well as the future. And yet, we see that entropy is indeed lower in the past. So the question is, why was entropy lower in the past?
eytan_il Posted January 19, 2013 Posted January 19, 2013 I don't understand that. Me neither. Entropy, without using logarithms and deep mathematical interpretations simply deals with statistically irreversible processes. For example, if half of the molecules of some gas have high thermal energy and half have low energy but they are mixed together, it will require energy to separate the mixture to hot gas and to cold gas. By the way, that is the form of energy that creates wind and storms, for example, tornado. In big words, entropy is a mathematical exprssion of mixture of physical states. It is easy to mix and the system releases energy as a result. To bring the system to its pre-mix state, it requires energy. The claim that entropy is symmetric with time seems to have no sense at all.
ACG52 Posted January 20, 2013 Posted January 20, 2013 (edited) And yet the equations are time symmetrical. So dealing with the closed system which is the universe, the question is why was entropy lower in the past? BTW, this isn't my idea, this comes from Brian Greene, in The Fabric Of The Cosmos. Edited January 20, 2013 by ACG52
Mike Smith Cosmos Posted January 20, 2013 Posted January 20, 2013 (edited) Entropy is You have been working close to your subject and is a big bite . Could you put the essence of your research in a laymans explanation Edited January 20, 2013 by Mike Smith Cosmos
eytan_il Posted January 20, 2013 Posted January 20, 2013 The second law of thermodynamics says that from any point in time, entropy increases toward the future. But the law of physics are time invarient, that is, they treat forward and backward in time the same. Therefore this implies that entropy should increase in the direction of the past, as well as the future. And yet, we see that entropy is indeed lower in the past. So the question is, why was entropy lower in the past? We can't be 100% sure that there are no mechanisms in Nature that violate the second law of thermodynamics. For example, it is possible that a super massive black hole has an upper mass limit such that mass absorbed by the black hole that exceeds this limit, is emitted in an unfamiliar form which later turns back into hydrogen. Such possible effects are not related to Hawking radiation ! We simply don't know. We should never forget that physics is a collection of models that quantitatively predict observations and as such, they are not the absolute truth but rather serve current and future technologies. We can't be sure about the second law of thermodynamics as long as we do not understand black holes in the quantum level. However, the accelerated cosmic expansion is a clue that in the cosmic level there is an irreversible process.
ACG52 Posted January 20, 2013 Posted January 20, 2013 For example, it is possible that a super massive black hole has an upper mass limit such that mass absorbed by the black hole that exceeds this limit, is emitted in an unfamiliar form which later turns back into hydrogen. What makes you think that's possible? Because you can frame the idea? We simply don't know. A very wishy-washy cop out. There's quite a bit we know, and to take the 'anything is possible' stance means you have to know nothing.
Mike Smith Cosmos Posted January 20, 2013 Posted January 20, 2013 (edited) We can't be 100% sure that there are no mechanisms in Nature that violate the second law of thermodynamics. We simply don't know. We should never forget that physics is a collection of models that quantitatively predict observations I really feel that in view of your research , you have something very valuable to offer here on the nature of Entropy. I am not sure i have managed to get my head around what it is you are saying. Could you possibly make a summary in simple yet accurate form .If you could be so kind. I think there is a fundamental truth lurking in here somewhere and would like to hear more. When I was doing a degree in telecommunications,we were going through a Fourier analysis of some waveform or other.The professor drew on the board a complete spectrum from negative to positive about the zero axis.( zero hertz ) The positive frequencies were a whole set of lines of various heights. He drew an opposite set of lines on the negative side, saying at the time "we only use the positive ones." ( I think it was something to do with broadband ). I was curious at the time ' how can you have negative frequency ?, it does not make sense ' I never did find out. Has this anything to do with the past in time ? and entropy , in the past . ? But past to who ? or What ( the relentless march of time, universal time or local time ? ) Edited January 20, 2013 by Mike Smith Cosmos
MigL Posted January 21, 2013 Posted January 21, 2013 (edited) Frequency has units of cycles per unit time ( ie. t^-1 ). Negative frequency has no physical meaning. Edited January 21, 2013 by MigL
eytan_il Posted January 23, 2013 Posted January 23, 2013 I really feel that in view of your research , you have something very valuable to offer here on the nature of Entropy. I am not sure i have managed to get my head around what it is you are saying. Could you possibly make a summary in simple yet accurate form .If you could be so kind. I think there is a fundamental truth lurking in here somewhere and would like to hear more. When I was doing a degree in telecommunications,we were going through a Fourier analysis of some waveform or other.The professor drew on the board a complete spectrum from negative to positive about the zero axis.( zero hertz ) The positive frequencies were a whole set of lines of various heights. He drew an opposite set of lines on the negative side, saying at the time "we only use the positive ones." ( I think it was something to do with broadband ). I was curious at the time ' how can you have negative frequency ?, it does not make sense ' I never did find out. Has this anything to do with the past in time ? and entropy , in the past . ? But past to who ? or What ( the relentless march of time, universal time or local time ? ) 1) Let us begin with the end, " ( the relentless march of time, universal time or local time ? ) " the universe does manifest some irreversibility in terms of universal time Universal time can be measured as maximal proper time along all geodesic curves connecting an event to the big bang. Each geodesic curve measures local maximum of proper time. From all such curves connecting an event 'e' to the big bang, we choose the ones along which absolute maximum proper time is measured. In that way, to each event in space time we can attach a number. Since this number grows along curves we can say that such a model of space-time has memory. You have to understand, however, the physicists do not like such an idea because it shows time which is absolute and not relative. For this reason my paper was rejected for several times despite mathematical beauty and simplicity. On the other hand it is possible that Nature does not really remember what is the absolute maximum time to each event because the theory I presented uses only the gradient of that time and the gradient is purely local. 2) "how can you have negative frequency ?". This question is tantamount to mine. How can we have absolute time ? We can in a mathematical description where the outcome with physical meaning is the gradient of such a time. The meaningful outcome of negative frequencies will be the reconstructed signal. A mathematical model has to work. Whether its intermediate products have a physical meaning or not, does not have to bother you as long as the outcome makes sense. 3) QM used imaginary functions above the Hilbert space with the self adjoint opertor. The value with physical meaning will not be the imaginary functions. It will be the square norm of such functions. There are many such examples in physics.
Mike Smith Cosmos Posted January 23, 2013 Posted January 23, 2013 (edited) 1) Let us begin with the end, " ( the relentless march of time, universal time or local time ? ) " the universe does manifest some irreversibility in terms of universal time Universal time can be measured as maximal proper time along all geodesic curves connecting an event to the big bang. Each geodesic curve measures local maximum of proper time. From all such curves connecting an event 'e' to the big bang, we choose the ones along which absolute maximum proper time is measured. In that way, to each event in space time we can attach a number. Since this number grows along curves we can say that such a model of space-time has memory. You have to understand, however, the physicists do not like such an idea because it shows time which is absolute and not relative. For this reason my paper was rejected for several times despite mathematical beauty and simplicity. On the other hand it is possible that Nature does not really remember what is the absolute maximum time to each event because the theory I presented uses only the gradient of that time and the gradient is purely local. 2) "how can you have negative frequency ?". This question is tantamount to mine. How can we have absolute time ? We can in a mathematical description where the outcome with physical meaning is the gradient of such a time. The meaningful outcome of negative frequencies will be the reconstructed signal. A mathematical model has to work. Whether its intermediate products have a physical meaning or not, does not have to bother you as long as the outcome makes sense. 3) QM used imaginary functions above the Hilbert space with the self adjoint opertor. The value with physical meaning will not be the imaginary functions. It will be the square norm of such functions. There are many such examples in physics. Ok I have sort of followed. Only just...! 1. Which seems to reconcile the notion of universal time "that relativistic physisists don't like" with local time by way of a gradient. That is sort of a dt/DT where t is local time and T is universal time ( or vice versa ) presumably . I like the sound of this 'gradient' idea of time ( is that your idea , and does it act as some form of measurement of entropy and its direction eg + ( plus ) if forward in time increase in entropy - (minus ) if decrease in entropy ' ? negative time ? '. 2. I sort of just about get this one but only just. You might need to go into a little more explanation as to how this fits with "mine" I presume you mean your thesis. Again this gradient of time, I like , as it has connotations of local perceptions of time ? may be.? 3. This one, you really are, going to have to , translate or explain more simply for me. Although I am a physics and maths trained individual, I will still need a bit of a guiding hand through No 3. However, I am getting a nice flavour, so if you would be so kind as to carry on , I would appreciate it. Thanks. Keep taking the Asprin Edited January 23, 2013 by Mike Smith Cosmos
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