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Author Topic: What does it mean to move from high entropy to low entropy?  (Read 28758 times)

Duan Gauche

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Duan Gauche  asked the Naked Scientists:
   
Hello Chris,
 
Thanks for all your wonderful podcasts on 702 I really enjoy them and the simple way in which you explain complex science to simple beings :-)
 
Could you please explain what is meant by: moving from high entropy to low entropy
 
Thanks you,
Duan Gauche

What do you think?

Ethos

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What does it mean to move from high entropy to low entropy?
« Reply #1 on: 04/06/2009 19:46:50 »
Entropy according to Websters:

A measure of the energy unavailable for useful work in a system, the tendency of an energy system to run down.

Therefore; High Entropy would indicate less energy available for useful work in a system. Low Entropy would suggest greater energy availability.

In our Universe, The Law of Entropy suggests that as time passes, less and less energy will become available for use. In some respects, Entropy is equivalent to the arrow of time................Ethos

Vern

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What does it mean to move from high entropy to low entropy?
« Reply #2 on: 04/06/2009 20:24:02 »
If the universe is eternal and steady state there must be some mechanism that reverses entropy. I suspect that ours might be such a universe. If so, the entropy reversing mechanism would be within galaxies.

Ethos

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What does it mean to move from high entropy to low entropy?
« Reply #3 on: 05/06/2009 00:03:33 »
If the universe is eternal and steady state there must be some mechanism that reverses entropy. I suspect that ours might be such a universe. If so, the entropy reversing mechanism would be within galaxies.
I agree Vern, someday the evidence for this may become clear. Right now, we can only wonder about the various possibilities. 

lyner

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What does it mean to move from high entropy to low entropy?
« Reply #4 on: 05/06/2009 15:25:58 »
One example of moving from high entropy to low entropy is tidying up your desk drawer. Entropy is a measure of disorder. To decrease entropy requires energy. Clearing up certainly knackers me!
To decrease the entropy, locally involved increasing the entropy of the Universe by more than the local decrease you obtained. That's, in effect, another statement of Thermodynamic Law.

LeeE

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What does it mean to move from high entropy to low entropy?
« Reply #5 on: 05/06/2009 16:05:12 »
I'm afraid that I can't go along with the idea of entropy being a measure of order or information - it's too subjective; would you describe some of Jackson Pollack's artworks as increasing or decreasing entropy?  If I were to spill a bag of rice on the floor it would normally be described as a reduction of entropy, but if I were to then gather up the rice and then deliberately arrange the grains on the floor in exactly the same pattern it would be regarded as an increase in entropy.

In purely energy terms though it is quite clear, and in line with the Webster definition of the term; entropy is the flow of energy down the gradient between two different energy levels.

JukriS

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What does it mean to move from high entropy to low entropy?
« Reply #6 on: 05/06/2009 16:48:28 »
Does entropy working also inside nucleus of atoms all a time?

If not, WHY not?


lyner

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What does it mean to move from high entropy to low entropy?
« Reply #7 on: 05/06/2009 18:02:09 »
I'm afraid that I can't go along with the idea of entropy being a measure of order or information - it's too subjective; would you describe some of Jackson Pollack's artworks as increasing or decreasing entropy?  If I were to spill a bag of rice on the floor it would normally be described as a reduction of entropy, but if I were to then gather up the rice and then deliberately arrange the grains on the floor in exactly the same pattern it would be regarded as an increase in entropy.
(Statistics isn't subjective and entropy applies to information).
Actually, that's precisely what's going on. When molecules of a hot gas mix with molecules of a cold gas, the overall entropy has increased; you've mixed things up..
Spilling rice is, essentially, increasing entropy because getting them back in the jar would  involve energy being put in.
Separating the fast molecules from the slow molecules (go on - try) would be the equivalent of re-sorting out your grains. The reconstructed pattern would have just as much information introduced (order) to it as if you lined them up into regular rows. Both actions would require energy to achieve, and wouldn't occur by chance (V. unlikely).
Look at a book on statistical thermodynamics; it's part of the explanation of these things.
p.s. I think you're getting defensive about the tidiness of you desk drawer.

Dunno whether thermodynamics can be applied to nuclear situations. I guess it would, only with different statistics.

If JP's painting turned out exactly as he had planned in his mind, then the entropy could be said to be minimal.

LeeE

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What does it mean to move from high entropy to low entropy?
« Reply #8 on: 07/06/2009 20:23:45 »
...you've mixed things up..

Oops!  :I

lyner

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What does it mean to move from high entropy to low entropy?
« Reply #9 on: 08/06/2009 10:17:40 »
That's entropy for you! :)

LeeE

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What does it mean to move from high entropy to low entropy?
« Reply #10 on: 08/06/2009 19:16:52 »
Lol  :D

 

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