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Author Topic: What is entropy? Is it a process or a result?  (Read 3627 times)

Offline Joe L. Ogan

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What is entropy? Is it a process or a result?
« on: 02/12/2009 19:09:58 »
I have seen entropy described as going from an organized situation to chaos.  I have seen given as an example, "Take a hot cup of coffee into a room temperature room and the cooling is entropy.  Would taking an ice cube into a room and having it melt be entropy? So, is it a process or a result?  Thanks, Joe L. Ogan


 

Offline JP

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What is entropy? Is it a process or a result?
« Reply #1 on: 03/12/2009 19:59:42 »
Entropy is a measure of the "disorder" in a system.  It's a measurement of a system, rather than a process or a result.  According to the second law of thermodynamics, the entropy in a closed system always tends to increase, which tells you something about how the system evolves in time. 

The cooling coffee cup is because the entropy in the system (which is the room containing the coffee cup + the coffee cup) increases in entropy, which happens when the mug loses heat the room gains that heat.  This is why the mug cools down.

Another example is if you arrange a deck of cards by suits.  If you shuffle the deck a bit, you expect it to get somewhat disorganized.  No amount of shuffling is expected to arrange it back in order of suits.  This is another example of the entropy (disorder) of the system increasing.
 

Offline Joe L. Ogan

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What is entropy? Is it a process or a result?
« Reply #2 on: 03/12/2009 20:08:56 »
Very, very interesting. Thank you.  Joe
 

Offline syhprum

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What is entropy? Is it a process or a result?
« Reply #3 on: 03/12/2009 22:21:50 »
Jpetruccelli

You state that no amount of shuffling will put a pack of cards back in order surely this is not correct the number of shuffles required is no doubt large but I am sure that anyone skilled in the art of statistics could calculate the number.
 

Offline Mr. Scientist

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What is entropy? Is it a process or a result?
« Reply #4 on: 03/12/2009 22:35:49 »
Jpetruccelli

You state that no amount of shuffling will put a pack of cards back in order surely this is not correct the number of shuffles required is no doubt large but I am sure that anyone skilled in the art of statistics could calculate the number.


Yes. This is correct. But implausible as an actual thing which may happen, even if you had a bottle with as little as 10^4 atoms.
 

Offline JP

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What is entropy? Is it a process or a result?
« Reply #5 on: 04/12/2009 00:21:07 »
You're right.  I shouldn't have said "no amount."  The same technically holds for the second law of thermodynamics.  It's just so improbable that entropy increases in a large system that for most purposes it never decreases in a closed system.  You could spontaneously have the heat in a room transfer into a cup of coffee so that it begins to boil, but we'll never see it happen since its so improbable.
 

Offline Joe L. Ogan

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What is entropy? Is it a process or a result?
« Reply #6 on: 04/12/2009 00:36:41 »
Not a scientific conjecture I am sure but I feel that it is so improbable that one could not be too far wrong to say "Never".  Just my unscientific thought.  Grin.  Joe L. Ogan
 

Offline Mr. Scientist

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What is entropy? Is it a process or a result?
« Reply #7 on: 04/12/2009 08:29:43 »
You're right.  I shouldn't have said "no amount."  The same technically holds for the second law of thermodynamics.  It's just so improbable that entropy increases in a large system that for most purposes it never decreases in a closed system.  You could spontaneously have the heat in a room transfer into a cup of coffee so that it begins to boil, but we'll never see it happen since its so improbable.

No, i don't think you should have been corrected as-so-much. You are actually right.
 

Offline Mr. Scientist

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What is entropy? Is it a process or a result?
« Reply #8 on: 04/12/2009 08:31:21 »
Our universe was simply not built to become simpler. It somehow desired this complexity, and without it wuld be disasterous for all celestial bodies and those living matters that can ponder on the irreversibility of entropy without suggesting a flip in time.
 

Offline LeeE

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What is entropy? Is it a process or a result?
« Reply #9 on: 04/12/2009 19:36:07 »
I have problems with defining entropy in terms of order because order is subjective.

I think the problem may be best illustrated with reference to paintings.  If we compare a finished painting, let's say the Mona Lisa, with the bare canvas and unmixed pigments and oils used to create the painting, which form would have the highest degree of order?

Let's now think of one of Jackson Pollack's splatter paintings and then imagine that an art forger makes a perfect replica of one of them.  The original work by Pollack would have started with cans of paint and a blank canvas, and then incorporated varying degrees of randomness in the creation of the work, so it could be argued that the final work was less ordered and had less entropy than the bare canvas and cans of paint.  However, when the art forger makes his perfect copy of the painting, using exactly the same materials, there is no randomness as the paint has to be applied precisely.  It seems to me then, that while the original work might be less ordered than the canvas and paint from which it is made, the perfect copy is more ordered.  Yet if both the original and the forgery are identical, how can they have different degrees of order?
 

Offline Mr. Scientist

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What is entropy? Is it a process or a result?
« Reply #10 on: 04/12/2009 21:59:23 »
I have problems with defining entropy in terms of order because order is subjective.

I think the problem may be best illustrated with reference to paintings.  If we compare a finished painting, let's say the Mona Lisa, with the bare canvas and unmixed pigments and oils used to create the painting, which form would have the highest degree of order?

Let's now think of one of Jackson Pollack's splatter paintings and then imagine that an art forger makes a perfect replica of one of them.  The original work by Pollack would have started with cans of paint and a blank canvas, and then incorporated varying degrees of randomness in the creation of the work, so it could be argued that the final work was less ordered and had less entropy than the bare canvas and cans of paint.  However, when the art forger makes his perfect copy of the painting, using exactly the same materials, there is no randomness as the paint has to be applied precisely.  It seems to me then, that while the original work might be less ordered than the canvas and paint from which it is made, the perfect copy is more ordered.  Yet if both the original and the forgery are identical, how can they have different degrees of order?

It's the use of the word ''order'' - there is one particular scientist/lecturer who would argue with me that language isn't a problem in physics, but it most clearly is a problem, because order to the subjective mind is when you a have a jigsaw puzzle that has been completed. Disorder in the case of entropy obviously does not comply to our natural understanding of order.
 

Offline Geezer

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What is entropy? Is it a process or a result?
« Reply #11 on: 05/12/2009 06:34:33 »
To talk of "disorder" in absolute terms is perhaps misleading. Many disordered systems could become "ordered". It's a numbers game. We should really talk about the probability of a system becoming ordered rather than saying it cannot become ordered. The probability may be infinitesimally small, but that does not mean it won't happen one second from now. It just means it's unlikely to happen one second from now.
« Last Edit: 05/12/2009 06:36:04 by Geezer »
 

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What is entropy? Is it a process or a result?
« Reply #11 on: 05/12/2009 06:34:33 »

 

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