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Author Topic:   Discussion of the 3 thermodynamic laws
portmaster1000
Inactive Member


Message 1 of 49 (131917)
08-09-2004 1:33 PM


Simplified Definitions
1st Law: Energy is Conserved (You cannot win)
2nd Law: Entropy Always Increases (You cannot break even)
3rd Law: No Absolute Zero (You cannot get out of the game)
I see the 2nd law mentioned alot on these forums.
I'm wondering if we can get a discussion going about how these laws are used in science. Maybe get some good examples of each one. What are the limitations of the laws?
I think a general informational thread would be education to all.
thanx
PM1K

Replies to this message:
 Message 3 by Loudmouth, posted 08-09-2004 2:04 PM portmaster1000 has replied
 Message 14 by happy_atheist, posted 08-21-2004 12:40 PM portmaster1000 has replied
 Message 15 by Brad McFall, posted 08-22-2004 9:53 AM portmaster1000 has not replied

  
AdminAsgara
Administrator (Idle past 2302 days)
Posts: 2073
From: The Universe
Joined: 10-11-2003


Message 2 of 49 (131921)
08-09-2004 1:46 PM


Thread moved here from the Proposed New Topics forum.

  
Loudmouth
Inactive Member


Message 3 of 49 (131931)
08-09-2004 2:04 PM
Reply to: Message 1 by portmaster1000
08-09-2004 1:33 PM


quote:
What are the limitations of the laws?
The 2nd law is most often misused in reference to information. The laws of thermodynamics concern themselves with the transfer of work and heat, not information. Therefore, saying that information in the genome should go towards disorder is like saying information should go down hill because of gravity. Thermodynamics says nothing about the order of subunits in a DNA polymer, nor does it say anything about the "decay" of the genome. Thermodynamic "order" is quite different than "order" used in everyday life. Go to http://www.talkorigins.org/faqs/thermo/probability.html for a detailed description.
And from CF001: Second Law of Thermodynamics :
The second law of thermodynamics says no such thing. It says heat will not spontaneously flow from a colder body to a warmer one, or equivalently, that total entropy (a measure of useful energy) in a closed system will not decrease. This doesn't prevent increasing order because
the earth is not a closed system; sunlight (with low entropy) shines on it and heat (with higher entropy) radiates off. This flow of energy, and the change in entropy which accompanies it, can and will power local decreases in entropy on earth.
entropy is not the same as disorder. Sometimes the two correspond, but sometimes order increases as entropy increases. [Aranda-Espinoza et al. 1999; Kestenbaum 1998] Entropy can even be used to produce order, such as in the sorting of molecules by size [Han and Craighead 2000].
even in a closed system, pockets of lower entropy can form if they are offset by increased entropy elsewhere in the system.
In short, order from disorder happens on earth all the time.

This message is a reply to:
 Message 1 by portmaster1000, posted 08-09-2004 1:33 PM portmaster1000 has replied

Replies to this message:
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helena 
Suspended Member (Idle past 5844 days)
Posts: 80
Joined: 03-27-2008


Message 4 of 49 (131981)
08-09-2004 3:27 PM


It is a very common misconception that the laws of thermodynamics are axioms, i.e. laws that can not be (positively) proven. They, however, can be nicely derived from a single postulate in statistical physics which states that in equilibrium every iso-energetic state has the same chance of being occupied.
Understanding this makes these 2nd law discussions even more futile than they usually are..
my $0.02

  
portmaster1000
Inactive Member


Message 5 of 49 (131991)
08-09-2004 4:10 PM
Reply to: Message 3 by Loudmouth
08-09-2004 2:04 PM


First and Third?
Cool link. Sunlight does represent a massive amount of energy being dumped on the system that is Earth.
How do all the laws tie together?
Any way to extend your sunlight to the Earth example to bring in examples of 1 and 3?
thanx
PM1K

This message is a reply to:
 Message 3 by Loudmouth, posted 08-09-2004 2:04 PM Loudmouth has replied

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Loudmouth
Inactive Member


Message 6 of 49 (131999)
08-09-2004 4:38 PM
Reply to: Message 5 by portmaster1000
08-09-2004 4:10 PM


Re: First and Third?
quote:
How do all the laws tie together?
They are the "rules" by which heat is transferred, and the results of heat transfer on matter. Breaking down the word "thermodynamics" into their roots you get thermo=heat and dynamo=movement. That is really what they boil down to (pardon the pun).
quote:
Any way to extend your sunlight to the Earth example to bring in examples of 1 and 3?
The first law is easy (matter/energy can not be destroyed nor created). The sun loses mass as it loses energy. The conservation of mass/energy is easily calculated in terms of nuclear reactions. This means that there is a limited amount of energy, and the system as a whole (earth AND sun) is indeed losing energy in the form of energy being expelled into space that is not stored as chemical or heat energy on earth. However, the sun will collapse and supernova before all of the possible energy is used up, so it isn't like a dying battery in that sense. What happens is that energy output in the core forces matter towards the outside of the sun. Once this energy begins to fade (and a few other stages that I can't remember right now) the sun collapses into a super-dense ball and then explodes outwards. As far as the earth, at some point the earth will be within the sun as expands outward (red giant phase). After that, the only reliable heat source may be magma at the center of the earth and what high energy chemical reactants that are left.
Right now, energy for life is stored in the form of energetic chemical bonds, namely glucose and ATP. These chemicals are the direct result of capturing high energy photons from the sun. Therefore, energy is created on earth from the created energy of the sun, kind of a hand-me-down energy chain. Glucose and ATP are then available to drive other reactions, especially those that are thermodynamically improbable (causing a decrease in entropy, but an overall increase in entropy since the system (sun and earth) is losing entropy).
The third law is more of a statement about every system, in that absolute zero (0 Kelvin) can never be reached. That is, everything is always vibrating to some degree, therefore everything is "sloppy" from an entropy point of view. However, scientists have been able to create environments that approach absolute zero. If I remember correctly, they have at least come within 1/1000th of a degree from 0 Kelvin, and may have come closer than that. Most of their research uses forces that slow the electrons within the atom instead of directly cooling the atoms like a "freezer".
I hope that wasn't too wordy. My inorganic chem and physics are a little rusty, so forgive me for any mistakes that others may point out.

This message is a reply to:
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Replies to this message:
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NosyNed
Member
Posts: 8996
From: Canada
Joined: 04-04-2003


Message 7 of 49 (132007)
08-09-2004 4:56 PM
Reply to: Message 6 by Loudmouth
08-09-2004 4:38 PM


Nit pic
so forgive me for any mistakes that others may point out.
The sun isn't big enough to go supernova. The expansion into a red giant phase is a nova event though but nothing like the magnitude of a supernova.
uses forces that slow the electrons within the atom
I'm pretty sure that's wrong. The electrons in an atom can't be "slowed", at least not if the atom is not ionized or excited. They use methods of cooling that are electromagnetic in nature though, not like fridge as you say.
This message has been edited by NosyNed, 08-09-2004 03:56 PM

This message is a reply to:
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Loudmouth
Inactive Member


Message 8 of 49 (132012)
08-09-2004 5:07 PM
Reply to: Message 7 by NosyNed
08-09-2004 4:56 PM


Re: Nit pic
Thanks Ned for the corrections. As to super-cooling, I thought I remebered them using lasers as well. I'll have to look it up again, but chances are you are right. Thanks again.

This message is a reply to:
 Message 7 by NosyNed, posted 08-09-2004 4:56 PM NosyNed has replied

Replies to this message:
 Message 9 by portmaster1000, posted 08-11-2004 10:51 PM Loudmouth has replied
 Message 10 by NosyNed, posted 08-11-2004 11:04 PM Loudmouth has replied

  
portmaster1000
Inactive Member


Message 9 of 49 (133048)
08-11-2004 10:51 PM
Reply to: Message 8 by Loudmouth
08-09-2004 5:07 PM


Absolute Zero
So, the third law is basically saying that you can never remove ALL heat from a system? Something like you can never reach zero if you start at 1 and keep dividing by 2, ie, 1/2, 1/4, 1/8,...?
thanx
PM1K

This message is a reply to:
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NosyNed
Member
Posts: 8996
From: Canada
Joined: 04-04-2003


Message 10 of 49 (133052)
08-11-2004 11:04 PM
Reply to: Message 8 by Loudmouth
08-09-2004 5:07 PM


Re: Nit pic
Yes, lasers are used for some cooling as well. (I could nit, nit pick and note that lasers are electromagentic. )
There are a bunch of different techniques (which I can't remember and they use them one after the other to push temperatures down and down.
IIRC, the bose-einstein condensate was finally cooled by allowing atoms to "evaporate". That is they were trapped in a magnetic (or laser light?? ) "well" and the "hot" ones "boiled" off leaving cold ones behind. That's from a lecture by the Nobel laureate who headed the work about 2 years ago so I don't remember clearly now.

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jar
Member (Idle past 394 days)
Posts: 34026
From: Texas!!
Joined: 04-20-2004


Message 11 of 49 (133056)
08-11-2004 11:13 PM
Reply to: Message 10 by NosyNed
08-11-2004 11:04 PM


Re: Nit pic
That was Cornell and Wieman IIRC. They used the laser to get most of the way down and then evaporative cooling to get the rest of the way to about 1 billionth of a degree above absolute zero.
I have a really hard time imagining what such molasses would actually look like. Strange.

Aslan is not a Tame Lion

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Loudmouth
Inactive Member


Message 12 of 49 (133242)
08-12-2004 1:20 PM
Reply to: Message 9 by portmaster1000
08-11-2004 10:51 PM


Re: Absolute Zero
quote:
So, the third law is basically saying that you can never remove ALL heat from a system? Something like you can never reach zero if you start at 1 and keep dividing by 2, ie, 1/2, 1/4, 1/8,...?
Yep, pretty much. To reach absolute zero you have to have a place that is below absolute zero for the heat to escape to. Since nothing can be below absolute zero it isn't possible to reach absolute zero. The laws outline why coldness can never be added to something, it is only heat and work that are able to move within a system.

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Loudmouth
Inactive Member


Message 13 of 49 (133245)
08-12-2004 1:24 PM
Reply to: Message 10 by NosyNed
08-11-2004 11:04 PM


Re: Nit pic
quote:
Yes, lasers are used for some cooling as well. (I could nit, nit pick and note that lasers are electromagentic. )
Touche, mon ami. Being a biologist, I often look over that fact. Physics professors used to tease us bio majors all of the time because we always separated light from the electromagnetic spectrum as if it had special qualities other than being detectable by the human retina. Of course, us bio geeks got our turn in anatomy, but being rational and having a strong stomach are two different things.
quote:
IIRC, the bose-einstein condensate was finally cooled by allowing atoms to "evaporate". That is they were trapped in a magnetic (or laser light?? ) "well" and the "hot" ones "boiled" off leaving cold ones behind. That's from a lecture by the Nobel laureate who headed the work about 2 years ago so I don't remember clearly now.
Makes perfect sense within kinetic gas laws. When you remove the most energetic atoms, you leave the less energetic atoms (ie the atoms carrying the least amount of heat).
This message has been edited by Loudmouth, 08-12-2004 12:25 PM

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happy_atheist
Member (Idle past 4913 days)
Posts: 326
Joined: 08-21-2004


Message 14 of 49 (135940)
08-21-2004 12:40 PM
Reply to: Message 1 by portmaster1000
08-09-2004 1:33 PM


My first post.
Hi everyone, this is my first post here but I have been "lurking" in the shadows for a while so I almost feel like I know the regulars
Anyway, to answer the OP I think the limitations of the laws (if limitiation is the right word) and the biggest misconception about the laws is that they are not absolute. Obviously nothing in science is absolute but rather an approximate model, but with Thermodynamics it's more than that. Even though it came about at the same time as classical (non-quantum) physics, it is itself grounded in quantum physics. Because of this it is statistical in nature (ie an average). The laws don't apply on a small scale level because it requires a massive number of particles for this behaviour to become as predictable as it is.
The example my Statistical Mechanics lecturer used to illustrate this was rolling dice. If you roll 2 dice (normal 6 sided) and add the scores together, the most likely score to get would be 7. If you plotted a probability distribution of the average score on each die it would be a smooth curve with a peak at 3.5, but with big probabilities that you could get other scores too. On the other hand, if you rolled a billion dice the probabilitiy distribution curve would look almost like a line at 3.5, dropping off to almost 0 either side of it. The more dice you roll, the more certain you can be that the average will be 3.5.
It's exactly the same with Thermodynamics. The reason why it is so deterministic is because it uses a huge number of particles (much more than a billion). The average behaviour then becomes very very predictable. The less particles that are involved, the more likely it is that you will observe something contrary to the laws of thermodynamics (just like the less dice you roll, the more likely it is you'll get an average other than 3.5).
This message has been edited by happy_atheist, 08-21-2004 11:41 AM

This message is a reply to:
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Brad McFall
Member (Idle past 5032 days)
Posts: 3428
From: Ithaca,NY, USA
Joined: 12-20-2001


Message 15 of 49 (136074)
08-22-2004 9:53 AM
Reply to: Message 1 by portmaster1000
08-09-2004 1:33 PM


limiTATION(s)?
I think there may be limitations in application of all 3 (I still have not thought through completely any one system where all three are used in the functional thing itself) when applicable to temporal hierarchies as to relative contributions from spontaneous and non-spontaneous processesing of STRUCTURE both stationary and non-stationary. So for instance if the energy to be divided on an average were attainted in the same ecology BOTH by light and chemical rxns but in different genetics it may still be homogoenous as to the mental copy of the energy differentiation provided there is some co-evolution. Interestingly if the two different lineages were to have complementary strucutre-funtion inversions of the space-time heterogeneity itersections equally across levels it might be possible to realize a case with the thermo laws and Gladyshev's law (1-2) found in theory in "Thermodynamics of Biological Evolutoin and Aging Supramolecular thermodynamics is a key to understanding phenomena of life. What is life from a physical chemist's viewpoint Adv. Gerontol. 2002 - Vol 9.P-49-53
quote:
The main reason fro this statement is connected with the phenomenon of metabolism and exchange of matter of different hierarchies. Lower level hierarchical structures are often reproduced in a medium of higher level hierarchical structures during the life time the latter.
My only concern so far seems to be is as to if the energy "units" cut across or between the figures of electron orbitals of atoms as soon as any coherent set of biological timings were to have been proposed.

This message is a reply to:
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