[CalgaryEng]

Since people on this site insist on talking about thermodynamics, I dusted off my old texts on this subject and did some reading. In the undergrad course the text we used was written by Wylen and Sonntag and titled Fundamentals of Classical Thermodynamics. I also took a graduate level course and text was The Elements of Classical Thermodynamics by A.B. Pippard. Pippard was Cavendish Professor of Physics at the University of Cambridge. He wrote his book in 1957, a couple of years before I was born.

Both books discuss first the Zeroeth Law of Thermodynamics. This law basically states the if objects A and C have the same temperature and B and C have the same temperature, then A and B have the same temperature. Pippard spends pages on this because it is rather vital to understanding the concept of temperature.

The First Law of Thermodynamics is discussed next by both texts. To do so they introduce the concepts of work and heat. Work of course is just the integral (sum over infinitesimal changes) of the dot product of force and displacement vectors. The discussion of heat is more substantial. Wylen and Sonntag caution that the thermodynamic definition of heat is somewhat different from the everyday understanding of the word. Basically, heat is defined as the energy that is transferred across a system boundary as a consequence of a temperature difference. Pippard introduces the concept of heat by first defining internal energy. Internal energy is a state function (determined by the state of a system and independent of the path taken to get there). The change of internal energy is simply equal to the work done on the system under adiathermal conditions. Heat is then defined as "a measure of the extent to which the conditions are not adiathermal." Hence, Pippard's statement of the First Law is simply: "Energy is conserved if heat is taken into account." Wylen and Sonntag state the first law as follows: "During any cycle a system undergoes, the cyclic integral of heat is equal to the cyclic integral of work." Since a cycle brings a system back to its original state, the net change of internal energy is zero, and we basically have work done equal to the extent to which process is not adiathermal. The statements are equivalent. Wylen and Sonntag then go on to define internal energy and enthalpy and discuss the application of the first law to a variety of common engineering situations.

In the discussion of the Second Law of Thermodynamics both texts present the Kelvin-Planck statement and the Clausius statement. Kevin-Planck tell us that it is impossible to construct a device that will operate in a cycle and produce no effect other than the extraction of heat from a single reservoir and the performance of an equal amount of work. The Clausius statement is that it is impossible to construct a device that operates in a cycle and produces no effect other than the transfer of heat from a cooler body to a hotter body. Wylen and Sonntag then go on to show how the violation of one statement implies the violation of the other statement. Pippard leaves this demonstration as an exercise for the reader. Pippard presents and discusses a third formulation due to Caratheodory: In the neighbourhood of any equilibrium state of a system there are states which are inaccessible by an adiathermal process.

The reader should note that in none of these formulations of the Second Law is there any mention of the concept of entropy. The concept of entropy is introduced by Pippard during his discussion of reversible cycles. He shows that the value of cyclic integral of the ratio q/T is zero for a reversible cycle, where q is heat transferred (in infinitesimal quantities) and T is temperature. He then introduces entropy as a state function where infinitesimal change of entropy is equal to infinitesimal change in heat transfer divided by temperature for a reversible change. (It is much simpler to write with a little calculus than to write in words. Obviously I am using the word infinitesimal as a substitute for a differential operator.)

Wylen and Sonntag also do a nice job of explaining entropy and, after fifty pages of discussion point out the change of entropy of an isolated system must be greater than or equal to zero. An isolated system is isolated. No heat transfer, no work done on it, no mass transfer. Isolated! The Earth is NOT an isolated system.

Both texts eventually get around to the Third Law of Thermodynamics, which states that by no finite series of processes is absolute zero attainable.

So, you may ask, what are the laws of thermodynamics, particularly the second law, really about? What they are really about is the fact that we want is to do useful things. We want to lift things, we want to fry our eggs, we want cold beer on hot days, we want to watch TV until our minds turn to jello. Engineers design systems for doing these kinds of tasks. Many of our designs involve extracting useful work by allowing heat to flow from a high temperature reservoir to a low temperature reservoir. The Second Law and its implications tell us with mathematical precision the maximum amount of useful work that can be extracted from such a system. In most cases we want to avoid waste heat. Heating up some river usually does no good for anyone.

In a strict sense, the amount of energy we have is always the same. Energy is conserved. The common use of the word energy is really known technically as availability. Availability is the measure of how much work can extracted from a system. It is work that we generally want to do. Since the use of the word energy to mean availability (or mechanical energy) is ubiquitous even among engineers, I will use it in this commonly understood way. Please note that with this notion of energy, energy is most definitely NOT conserved. Using a quantity of natural gas to heat your bath water is not a reversible process. The energy of the natural gas is gone because you cannot get any practical amount of useful work from a tub of lukewarm water.

In the era of cheap energy relatively little serious attention has been paid to matching the source of energy with the application. Has it occurred to anyone just how insanely wasteful it is to use the high temperature flame of natural gas to keep a home heated to room temperature. If we used the natural gas to run an engine to generate electricity and used the waste heat from this process to heat our home, we would get a much bigger bang for our buck. Unfortunately, since the cost of natural gas has been practically zero for several decades, using it in an efficient way has not been economically justified.

A couple of decades ago I remember reading the text from a speech given by Amory Lovins. In discussing the need of a new electrical power generating facility he pointed out that the facility would be unnecessary if people in the area simply separated their refrigerators from their stoves. After reading the article I began paying attention to the number of homes in which the stove is pushed up against the refrigerator. The number was large. One of the facts that gives me some comfort about the future (there are lots of other facts which give me severe discomfort) is that North Americans waste so much energy. It will be relatively easy to become much more efficient.

This is my first post to this forum (or any other). For the last few months I have been reading about peak oil in books and on the web. I have spent many hours reading the forums at PeakOil.com. I would like to thank many of you for your intelligent and informative posts. I would also like to suggest that some of you should do a little reading and/or thinking before writing. Some others should read the posts to which they are replying before they reply. There are a few posters who should be entirely ignored, especially those who continue to hold positions after being thoroughly refuted.

[Carmiac]

Personally, my favorite explanation of entropy is by the grand master himself, MC Hawking.

Entropy - MC Hawking

Trash Talk
Harm me with harmony.
Doomsday, drop a load on 'em.

Verse 1
Entropy, how can I explain it? I'll take it frame by frame it,
to have you all jumping, shouting saying it.
Let's just say that it's a measure of disorder,
in a system that is closed, like with a border.
It's sorta, like a, well a measurement of randomness,
proposed in 1850 by a German, but wait I digress.
"What the fuck is entropy?", I here the people still exclaiming,
it seems I gotta start the explaining.

You ever drop an egg and on the floor you see it break?
You go and get a mop so you can clean up your mistake.
But did you ever stop to ponder why we know it's true,
if you drop a broken egg you will not get an egg that's new.

That's entropy or E-N-T-R-O to the P to the Y,
the reason why the sun will one day all burn out and die.
Order from disorder is a scientific rarity,
allow me to explain it with a little bit more clarity.
Did I say rarity? I meant impossibility,
at least in a closed system there will always be more entropy.
That's entropy and I hope that you're all down with it,
if you are here's your membership.

Chorus
You down with entropy?
Yeah, you know me! (x3)
Who's down with entropy?
Every last homey!

Verse 2
Defining entropy as disorder's not complete,
'cause disorder as a definition doesn't cover heat.
So my first definition I would now like to withdraw,
and offer one that fits thermodynamics second law.
First we need to understand that entropy is energy,
energy that can't be used to state it more specifically.
In a closed system entropy always goes up,
that's the second law, now you know what's up.

You can't win, you can't break even, you can't leave the game,
'cause entropy will take it all 'though it seems a shame.
The second law, as we now know, is quite clear to state,
that entropy must increase and not dissipate.

Creationists always try to use the second law,
to disprove evolution, but their theory has a flaw.
The second law is quite precise about where it applies,
only in a closed system must the entropy count rise.
The earth's not a closed system' it's powered by the sun,
so fuck the damn creationists, Doomsday get my gun!
That, in a nutshell, is what entropy's about,
you're now down with a discount.

Chorus

Trash Talk
Hit it!
Doomsday, kick it in!

[MonteQuest]

Calgary,

Good post, however over most of the readers heads here. What point were you trying to make when you wrote?:

Isolated! The Earth is NOT an isolated system.

No, it is a closed system: exchanges energy but not matter. Still subject to the Laws.

Monte

[MonteQuest]

Point of clarity:

There are three types of systems that the laws apply to:

Isolated, no exchange of energy or matter. The Universe is the only isolated system we know of.

Closed, an exchange of energy but not matter. The earth is a closed system.

Open, living organisms are open systems where both energy and matter are exchanged.

Sometimes the words "isolated" and "closed" are used to mean the same thing, an isolated system.

[smiley]

$this->bbcode_second_pass_quote('', 'I')t's called non-equilibrium thermodynamics. No mystery here. I covered this at length in one of my threads.

[MrBean]

$this->bbcode_second_pass_quote('MonteQuest', 'P')oint of clarity:

There are three types of systems that the laws apply to:

Isolated, no exchange of energy or matter. The Universe is the only isolated system we know of.

Closed, an exchange of energy but not matter. The earth is a closed system.

Open, living organisms are open systems where both energy and matter are exchanged.

Sometimes the words "isolated" and "closed" are used to mean the same thing, an isolated system.

[stayathomedad]

wow, this is a great discussion, I love it, we may be getting somewhere.

About the post which calgary had, yes it was long and complex, but it got the concept.

monte has a lot of good points as well, and the e=m*c^2 holds ground in the sense that energy and mass are the same, the problem is converting it. the way photosynthesis works is that the light captured facilitates a chemical reaction. this reaction depends on that there is existing mass, such as small molecules you can do something with.

self organizing systems: organisms are self organizing systems, just much like a hurrican would be. and they spend a lot of energy to do just that. and eventually: they go pooffff.....

when I was in grad school we had our own labelling for the laws:

1.) You cannot win
2.) You can only loose
3.) And they won't let you out of the game

whatever you are, a closed or a open system, these laws apply universally, and there is no known observation from that.

For example entropy: we live of the waste the sun makes, just like roaches from dirt in the kitchen.

there was a perpetuum mobile web site quoted here in this discussion, but you look at it, this is no perpetuum mobile, most of it depends on a old well known effect: water power, such as the mills of old. This is how they work: the sun evaporates water, the water comes back out as rain, and as the water runs back to the ocean (the thermodynamic sink), we can use it to power things. there was no single indication on that page that would invalidate the laws of thermodynamics.

Cheers

[trespam]

Wow, lots of words on thermodynamics and entropy. Let me try to summarize:

1. First law: energy/matter not created or destroyed (takes into account Einstein E=MC**2)

2. Second law: Entropy of closed system increases. Which is really just another way to say that energy goes from more organized forms (e.g. fossil fuels) to disorganized forms (e.g. heat).

3. There are boundary or limiting regions for thermodynamics that are in question, e.g. the entropy of the universe and quantum mechanical issues. Both are currently irrelevant to human scale problem solving, e.g. how we acquire energy. The small scale and large scale uncertainties about thermodynamics and entropy have no bearing on energizing humanity.

4. The earth can largely be considered a closed system other than the radiation that falls on it from the sun and the radiation that is projected back into space.

5. The only ongoing (income) source of low-entropy energy that is available to humans is sunlight. Low-entropy fossil fuels and uranium are capital, not income. Fusion might be a source of low-entropy energy in the future, not now.

That's really about it. There is no perpetual motion machine, and our primary goals are to (a) reduce the increase of entropy on earth as we use capital energy sources (conservation, effiency) and (b) draw increasingly on income sources of low entropy (solar). Hydro is one, but it is very limited. Photovoltaics, wind, and bio-fuels are another. That's about it other than some tidal energy (of gravitational origin) and geothermal (caused by nuclear fission in the earth).

[MrBean]

Here's one quote I like. Not targeted at anyone, I just think it's worth sharing:

"You are showing a closed mind not an open one. The second law of thermodynamics then demands that your level of confusion increase" - Jack Sarfatti answering somebody in Newsgroups discussion

[MonteQuest]

$this->bbcode_second_pass_quote('smiley', ' ')Of course the workings of a human being can be well explained by thermodynamics, but not their origin. Even non equilibrium thermodynamics do not explain the origin of complex structures. Why do they form?

[MonteQuest]

Oops! Typo. I meant to say: Evolution means the creation of larger and larger islands of order at the expense of ever greater seas of disorder in the world.

[MonteQuest]

$this->bbcode_second_pass_quote('', '2'). Second law: Entropy of closed system increases. Which is really just another way to say that energy goes from more organized forms (e.g. fossil fuels) to disorganized forms (e.g. heat).

[Agren]

$this->bbcode_second_pass_quote('', 'E')volution means the creation of larger and larger islands of disorder at the expense of ever greater seas of disorder in the world.

[trespam]

$this->bbcode_second_pass_quote('MonteQuest', '')$this->bbcode_second_pass_quote('', '2'). Second law: Entropy of closed system increases. Which is really just another way to say that energy goes from more organized forms (e.g. fossil fuels) to disorganized forms (e.g. heat).

[smiley]

$this->bbcode_second_pass_quote('', 'L')ife must then violate the Second Law. Sorry, but life cannot escape the iron hand of the entropy law.

[bentstrider]

Seems to me most everyone on this board follows and quotes this thing as if it were an actual law you could get killed for not following.
I'll bet anything that the whole "make energy from nowhere" idea was tried by many. But due to respected scholars and academic marvelists wanting to avoid shame and humiliation, they have these people erased.
Take this guy for example:
http://www.zpenergy.com/modules.php?nam ... le&sid=738
Eugene Mallove was researching intensively into the aspects zero-point energy. He brought up my above idea on the coasttocoastam radio show in February of this year.
http://www.coasttocoastam.com/
Another thing that makes this mans death so shocking was his economic status, he wasn't really rich or influential in a celebrity sort of way.

[ohanian]

$this->bbcode_second_pass_quote('bentstrider', 'S')eems to me most everyone on this board follows and quotes this thing as if it were an actual law you could get killed for not following.
I'll bet anything that the whole "make energy from nowhere" idea was tried by many. But due to respected scholars and academic marvelists wanting to avoid shame and humiliation, they have these people erased.
Take this guy for example:
http://www.zpenergy.com/modules.php?nam ... le&sid=738
Eugene Mallove was researching intensively into the aspects zero-point energy. He brought up my above idea on the coasttocoastam radio show in February of this year.
http://www.coasttocoastam.com/
Another thing that makes this mans death so shocking was his economic status, he wasn't really rich or influential in a celebrity sort of way.

[bentstrider]

My point exactly.
Most everyone on Earth would take that as complete poppy-shit.
And don't even get the Chinese involved in this.
They have a tendency to go after things that have already been widely proven in the science world and copy them.
Mallove could've been killed by anyone though.
Something he was working was almost about to be proven right.
Then someone trying to protect their rep was put down.
But, I forgot to stress the main point of my post.
On why everyone quotes the Laws of Thermodynamics as if they are an actual mandated law.
Laws are meant to be broken. And if the law gets proven wrong, then shove it up the donkeys sphincter.

[TrueKaiser]

Laws of Thermodynamics are not legal laws. they are laws of physics.
http://www.emc.maricopa.edu/faculty/far ... Ener1.html
these can not be broken.

[katkinkate]

Many studies in zeropoint energy and quantum physics seem to hint Newton's laws of physics may be more like general principles. At least many adherents of zpenergy give that impression.