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Post by Progenitor A on Feb 19, 2011 9:19:22 GMT 1
The 2nd Law of Thermodynamics tells us that heat cannot flow from a cold to a hot body.
Fair enough
This leads to the concept of entropy whereby energy, although never destroyed (cannot be proved incidentally) disperses so that it cannot be re-used. The ultimate state of entropy in a thermodynamic system would be a uniform temeperature at all points, si that no useful work can ever be done.
So lets take the universe. In time all the energy in the universe will disperse so that it is at a uniform temperature everywhere. Then we have complete entropy
But do we?
For, presumably matter in the form of dead planets and clouds of uniform-tempertature gas will still be there
And as we know, Einsten tells us that mass is simply another form of energy
So in this uniform soup of constant energu we have big lumps of energy
And that is not total energy entropy is it?
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Post by abacus9900 on Feb 19, 2011 11:21:55 GMT 1
The 2nd Law of Thermodynamics tells us that heat cannot flow from a cold to a hot body. Fair enough This leads to the concept of entropy whereby energy, although never destroyed (cannot be proved incidentally) disperses so that it cannot be re-used. The ultimate state of entropy in a thermodynamic system would be a uniform temeperature at all points, si that no useful work can ever be done. So lets take the universe. In time all the energy in the universe will disperse so that it is at a uniform temperature everywhere. Then we have complete entropy But do we? For, presumably matter in the form of dead planets and clouds of uniform-tempertature gas will still be there And as we know, Einsten tells us that mass is simply another form of energy So in this uniform soup of constant energu we have big lumps of energy And that is not total energy entropy is it? I think the point is it is about 'organized' energy naymissus, so that although energy cannot be destroyed it will all eventually be dispersed from an organized state to a disorganized one. You won't get people, planets, plants etc. but a thin 'soup' of 'unharnessed' energy.
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Post by Progenitor A on Feb 19, 2011 13:48:37 GMT 1
The 2nd Law of Thermodynamics tells us that heat cannot flow from a cold to a hot body. Fair enough This leads to the concept of entropy whereby energy, although never destroyed (cannot be proved incidentally) disperses so that it cannot be re-used. The ultimate state of entropy in a thermodynamic system would be a uniform temeperature at all points, si that no useful work can ever be done. So lets take the universe. In time all the energy in the universe will disperse so that it is at a uniform temperature everywhere. Then we have complete entropy But do we? For, presumably matter in the form of dead planets and clouds of uniform-tempertature gas will still be there And as we know, Einsten tells us that mass is simply another form of energy So in this uniform soup of constant energu we have big lumps of energy And that is not total energy entropy is it? I think the point is it is about 'organized' energy naymissus, so that although energy cannot be destroyed it will all eventually be dispersed from an organized state to a disorganized one. You won't get people, planets, plants etc. but a thin 'soup' of 'unharnessed' energy. So would we never reach the final stage of entropy unless all the planets and other matter had converted to energy and dispersed?
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Post by abacus9900 on Feb 19, 2011 13:58:24 GMT 1
Well, think of the universe as a clock naymissus. In the beginning (the BB) the universe is fully wound up and has the most usable energy but over immense amounts of time the universe 'unwinds' and the energy that can used in any meaningful way becomes less and less organized and wispy and effectively lost in terms of building or sustaining anything. I suppose eventually, although energy cannot be destroyed, it is kind of like stagnant water - not a lot of good!
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Post by speakertoanimals on Feb 22, 2011 15:58:24 GMT 1
You can't try and sneak in that mass is energy, without mentioning the effects of gravity as well. And hence black holes, and Hawking and the balack hole information stuff..........................
Entropy ISN'T just energy, because you can't necessarily get the energy out that is the mass, say, of an electron, or a proton. Hence it isn't available to do work, unless there is some lower-energy states to which that particle can decay. SO if protons could decay (albeit on an unimagfinably large time-scale), that would give a different maximum entropy state of the universe than if protons did not decay.
Entropy ISN'T just about energy, it is about order and disorder as well.
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Post by abacus9900 on Feb 28, 2011 21:39:43 GMT 1
You can't try and sneak in that mass is energy, without mentioning the effects of gravity as well. And hence black holes, and Hawking and the balack hole information stuff.......................... Entropy ISN'T just energy, because you can't necessarily get the energy out that is the mass, say, of an electron, or a proton. Hence it isn't available to do work, unless there is some lower-energy states to which that particle can decay. SO if protons could decay (albeit on an unimagfinably large time-scale), that would give a different maximum entropy state of the universe than if protons did not decay. Entropy ISN'T just about energy, it is about order and disorder as well. If you had taken the time to read my post properly you would have noticed that I did indeed point out that energy becomes disorganised over time and therefore useless. I do not mind being pulled up for a genuine error but not for something you had mistakenly overlooked.
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Post by speakertoanimals on Mar 1, 2011 13:47:59 GMT 1
And that's not right either..................
Would be better if you tried to understand the definitions of entropy actually used in physics, rather than some wishy-washy hand-waving folk science description in terms of 'disorganised energy'............
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Post by abacus9900 on Mar 1, 2011 13:57:09 GMT 1
And that's not right either.................. Would be better if you tried to understand the definitions of entropy actually used in physics, rather than some wishy-washy hand-waving folk science description in terms of 'disorganised energy'............ Ooooook, look here: "Entropy describes the tendency for systems to go from a state of higher organization to a state of lowest organization on a molecular level. In your day-to-day life, you intuitively understand how entropy works whenever you pour sugar in your coffee or melt an ice cube in a glass. Entropy can affect the space into which a substance spreads, its phase change from solid to liquid to gas, or its position. In physics, entropy is a mathematical measurement of a change from greater to lesser potential energy, related to the second law of thermodynamics." www.wisegeek.com/what-is-entropy.htmYou think you're a better man than me? Naw.
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Post by speakertoanimals on Mar 1, 2011 15:10:11 GMT 1
Organisation is NOT the same as organised (or disorganised) energy. Its actually mixing up the definitions in terms of microstates and macrostates (organised and disorganised being one way of thinking of the number of microstates), with the definition in terms of useful work that can be extracted.
As I said, you got it wrong, and don't know enough to be able to see that................
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Post by abacus9900 on Mar 1, 2011 15:32:33 GMT 1
Organisation is NOT the same as organised (or disorganised) energy. Its actually mixing up the definitions in terms of microstates and macrostates (organised and disorganised being one way of thinking of the number of microstates), with the definition in terms of useful work that can be extracted. Well, this is just one more example of your disastrous attempts at 'explaining.' Could you use proper English please, not this personal, confused gibberish? Even naymissus would not understand it and he's a professional engineer! Thank you.
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Post by speakertoanimals on Mar 1, 2011 17:09:56 GMT 1
Its just standard physics terminology -- hence if you don't KNOW what the terms microstate and macrostate mean, means you don't understand entropy in physics, and how disorder or order are quantified.
Saying it is not proper english just demonstrates your own ignorance of the relevant physics, so thank you for proving my point..........
If you want an EXPLANATION, I might if you ask nicely, but if you're going to call anything I say as gibberish (which is your record so far), I won't bother. Just showing you've got no idea is good enough for now.
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Post by abacus9900 on Mar 1, 2011 17:30:09 GMT 1
Its just standard physics terminology -- hence if you don't KNOW what the terms microstate and macrostate mean, means you don't understand entropy in physics, and how disorder or order are quantified. Saying it is not proper english just demonstrates your own ignorance of the relevant physics, so thank you for proving my point.......... If you want an EXPLANATION, I might if you ask nicely, but if you're going to call anything I say as gibberish (which is your record so far), I won't bother. Just showing you've got no idea is good enough for now. Standard physics terminology is not really good for non-physicists is it? It's like an expert in electronics using standard electronics terminology - it would just baffle a beginner. One has to learn the 'language' first. Go on then surprise me.
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Post by speakertoanimals on Mar 1, 2011 17:52:29 GMT 1
Except you quite happily used the word entropy, which is hardly standard english, so stop playing the poor non-specialist card, no one is convinced by that bollocks.............................
The point was NOT that it was physics terminology, the point was that you referred to my use of it as 'personal, confused gibberish' which even you now seem to be saying was incorrect.....................
Why do you try to discuss physics when you aren't willing to try and learn the terminology, even when someone does explain it.............
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Post by speakertoanimals on Mar 2, 2011 2:35:20 GMT 1
The really mysterious thing about entropy is that the basic laws of physics are invariant with respect to time reversal. Yet the macroscopic effects are not. Why we see a cup shatter, but never reform, is a deep and dark mystery. But a mystery that will forever remain a mystery wrapped in an enigma to those not willing or able to try and understand the basic definitions.
As regards microstates and macrostates, its quite simple. Take a box of gas, with a given total energy and volume. There are many ways that that energy can be apportioned amongst the individual molecules. Some (such as half the molecules moving to the left, and the other half to the right), are valid microstates. Yet overwhelmed by those where the moleules are moving about randomly, with some having a bit more energy than others, some a little less. Counting the number of microstates that could belong to a defined macrostates (fixed total energy and volume), and taking the log of the result provides a quantification of entropy.
Why the log? Because if we have two isolated boxes of gas, with A states for one, B for the other, we want the entropy of the two to be a simple sum. Hence since the total number of states for the two combined is A times B (for every A state in one box, we can have any of the B states in the other). Hence to get an additive entropy, we take a log, since log(A times B) = log A + log B.
So what are states of low entropy? If every molecule in the box is in its ground state (neglecting quantum statistics effects for the moment), then we have one microstate, in effect. Hence low total energy/low temperature equals low entropy and low disorder. Add more energy, and the more you add, the more ways there are to apportion it out amongst the molecules, hence the higher the entropy.
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Post by Progenitor A on Mar 2, 2011 8:17:12 GMT 1
The really mysterious thing about entropy is that the basic laws of physics are invariant with respect to time reversal. Yet the macroscopic effects are not. Why we see a cup shatter, but never reform, is a deep and dark mystery. But a mystery that will forever remain a mystery wrapped in an enigma to those not willing or able to try and understand the basic definitions. As regards microstates and macrostates, its quite simple. Take a box of gas, with a given total energy and volume. There are many ways that that energy can be apportioned amongst the individual molecules. Some (such as half the molecules moving to the left, and the other half to the right), are valid microstates. Yet overwhelmed by those where the moleules are moving about randomly, with some having a bit more energy than others, some a little less. Counting the number of microstates that could belong to a defined macrostates (fixed total energy and volume), and taking the log of the result provides a quantification of entropy. Why the log? Because if we have two isolated boxes of gas, with A states for one, B for the other, we want the entropy of the two to be a simple sum. Hence since the total number of states for the two combined is A times B (for every A state in one box, we can have any of the B states in the other). Hence to get an additive entropy, we take a log, since log(A times B) = log A + log B. So what are states of low entropy? If every molecule in the box is in its ground state (neglecting quantum statistics effects for the moment), then we have one microstate, in effect. Hence low total energy/low temperature equals low entropy and low disorder. Add more energy, and the more you add, the more ways there are to apportion it out amongst the molecules, hence the higher the entropy. More and more regurgitated half-understood nonsense friom the mistress of godbbledgook and innumeracy and contradiction
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