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Author
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Topic: Life: process that decreases entropy locally
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Jurie
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Member # 716
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posted 29. February 2004 21:53
Life as a process that has the ability to decrease entropy locally
Reading the thread on Granville Sewell's paper, set me thinking on the issue of defining Life. I came up with a definition that eventually withstood my own scrutiny; I present it here.
"Life is defined as an energy expending process that can decrease entropy locally, in a sustainable manner."
Some definitions are in order:
"energy expending process" means a series of actions, executed by whatever means and requiring free energy to do it, that belong together in the sense that all the actions are required to complete the process;
"ability to decrease entropy" means the outcome of the process has the result that entropy is not increased along the maximising path, but is often decreased;
"locally" means the process operates in a limited scope while at the same time increasing the entropy in a wider scope, such that the global entropy increases; "locally" also means for a limited time, that is until that particular organism dies; "locally" can sensibly be confined to the extent of the particular organism, i.e. its skin, or cell wall;
"sustainable manner" is the ability to resist the maximal rate of entropy increase for as long as the means to do so is present; it would include the means to effect self-repair and reproduction from the environment in order to ensure sustainability.
It is proposed that only life can resist the tendency of entropy to increase locally in a sustainable manner. Even stronger, it is proposed that life is a process that decreases entropy locally. It is important to qualify here that intelligent life can design processes that has the ability to decrease entropy locally, but which would not necessarily be in a sustainable manner, so these would not qualify as being life, merely as an effect of intelligent life.
I would further propose that this definition by its very nature, excludes the possibility of life arising spontaneously from non-life. I would further propose that the idea of order arising spontaneously from disorder as a function to maximise the production of entropy, is in the opposite direction than life; that life, far from being an entropy-maximising process, is quite the opposite - it is a sustained process that operates far from the entropy maximising path.
Jurie
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David L. Hagen
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posted 29. February 2004 23:03
Encouraging start with provocative implications.
Suggest you clarify your comment: "can design processes that [have ]("has")the ability to decrease entropy locally" when those processes are "in a sustainable manner".
What if we set up a system in the Sahara to make silicon crystals from sand using battery backed PV solar energy with RAID type configurations and controllers. That could nominally be "in a sustainable manner" for a very long time as the supply of sand lasted and the system did not break down?
Suggest you expand your discussion between "Intelligent Designer" and "life", as "Life" generally has many dimensions and meanings, ranging from blue green algae to the Supreme Being.
Do you need to restrict your definition to "Natural life"? Or are you proposing that all "supernatural life" and/or "non-natural life" is capable of meeting your definition and comments?
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Jurie
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posted 29. February 2004 23:51
quote:
Suggest you clarify your comment: "can design processes that [have ]("has")the ability to decrease entropy locally" when those processes are "in a sustainable manner".
Thanks. Sustainable manner: The ability of the process to extend beyond one "machine"; that is, when the machine breaks down due to wear, other machines made by the original one are already busy executing the same process. If we make an unlimited amount of energy and material available to the process, then the process would continue indefinitely, in one machine after another, without violating the SLOT.
An example of a process designed by intelligent life that has the ability to decrease entropy while the means to do so is available, is an apple sorter. A large number of apples mixed up in size and color is dumped in a bin at the start of the process, and boxes of packed apples sorted by color and size is the result of the process. In this case, the means to do so would include machines, energy, measuring apparatus, sorting logic and boxes. Would this sorter qualify as life? No. The manner is not sustainable; no new sorters are built by the sorter; once the machines are worn out, sorting would grind to a halt. In the case of life, the means of executing the process is continually renewed and replaced, ensuring that the process is sustainable.
I think if those machines in the desert could build new ones from the sand and the solar energy, then according to the definition would be indistinguishable from life. But I don't think we can assume they won't break down; it is precisely the SLOT that gives force to the definition, that also disqualifies that assumption.
I did consider that a "Supreme Being" is also alive, but that this definition does not extend there; I did not want to include super-natural life in the definition so as to keep it useful. So this definition is phrased only for natural and artificial life.
[ 01. March 2004, 00:10: Message edited by: Jurie ]
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Evan
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posted 01. March 2004 07:50
Jurie writes, “ I came up with a definition that eventually withstood my own scrutiny; I present it here. Life is defined as an energy expending process that can decrease entropy locally, in a sustainable manner."
I thought this was a well-accepted fact.
Jurie also writes, “I would further propose that this definition by its very nature, excludes the possibility of life arising spontaneously from non-life.”
I always wonder what people mean by “spontaneously” in this context - maybe Jurie could clarify. Do you mean “all at once” (as in the phrase “spontaneous combustion”), or does your use of spontaneous include a long process of many steps - spontaneous effectively meaning “due to natural causes wihout outside influence.”
Thanks.
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Jurie
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posted 01. March 2004 17:54
Well-established fact: This definition is limited and perhaps self-evident; I admit to not being well-read on possible definitions, but I have found a number of sources that show just how difficult it is to come up with one that might serve as a working definition. I did not find any discussion on ISCID boards on it; I did a bit of wider search after coming up with it, and found a discussion in one place that seems to match this definition very closely. The advantage of having a formal definition, even a self-evident one, is you can test cases against it.
spontaneously: Since according to this definition, life is a process that expends energy and bucks the trend of decay, it is hard to see how such processes might arise, step-by-step, regardless of the size of the evolutionary steps. The point is life goes against the trend; how can something that goes against the trend arise? Even just a small step? The point is that such trend-bucking steps are not available to select from in the first place.
I will explain closer: At www.entropylaw.com there is a discussion about how order can arise spontaneously in open systems and gave the example of the Benard convection cell. It is pointed out there that this local order speeds up the production of entropy. This is of course very interesting, but in thinking about it, it seems that life is really far away from such entropy maximising processes.
Consider the example of rabbit-world, a world with a balanced population of rabbits and grass. The number of rabbits and the amount of grass remains the same over time, so the entropy in this world remains roughly constant. Overall, from space, this world does not appear to be different from a dead world with exactly the same atom constituents. Solar energy goes in, heat is radiated out. But in the dead world, the carbon is in the atmosphere bound to oxygen and is at a higher temperature due to the increased greenhouse effect. So, on a planet scale, the dead world has a higher entropy: If all the rabbits and grass suddenly die, rabbit-world will stabilise at the same higher temperature as the dead world. I don't see how the rabbit world is an entropy-maximising process; the world temperature indicates the opposite. It is a process that works against the trend instead of speeding the trend. Since these are diametrically opposite, how can such processes arise spontaneously, even step by step?
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RBH
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posted 01. March 2004 18:32
Jurie wrote quote:
spontaneously: Since according to this definition, life is a process that expends energy and bucks the trend of decay, it is hard to see how such processes might arise, step-by-step, regardless of the size of the evolutionary steps. The point is life goes against the trend; how can something that goes against the trend arise? Even just a small step? The point is that such trend-bucking steps are not available to select from in the first place.
But the non-biotic physical and chemical world is stuffed full of sytems that locally expend energy and in the process, "buck the trend of decay." That's a significant thrust of Prigogine's work in physics on thermodynamically far-from-equilibrium systems (Nobel in 1977 for it). Just as water can (locally) flow uphill when it encounters a rock in a rapids, so local decreasese in entropy can occur in open physical and chemical systems. And it's the latter, in local entropy decreases in chemical systems, that Stuart Kauffman, for example, invokes in his conception of self-organizing auto-catalytic systems (see Origins of Order, pp. 387-393).
In general, if energy flows through an open physical system whose substrate - the physical medium in which the energy is transmitted - has discontinuities, there will likely be local decreases in entropy associated with those discontinuities.
RBH
[ 01. March 2004, 18:40: Message edited by: RBH ]
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Evan
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posted 01. March 2004 18:59
It is important to realize that, as RBH pointed out, that inanimate (non-biotic) system can also have a local decrease in entropy - this is not restricted to life.
So when Jurie wote, “ Life is defined as an energy expending process that can decrease entropy locally, in a sustainable manner,"
I was wrong to say “I thought this was a well-accepted fact.”
It is an accepted fact that life decreases entropy locally - this is a property of life. However, it is wrong to consider this a defining property of life, because things other than life also have this property.
Juire writes,
quote:
Since according to this definition, life is a process that expends energy and bucks the trend of decay, it is hard to see how such processes might arise, step-by-step, regardless of the size of the evolutionary steps. The point is life goes against the trend; how can something that goes against the trend arise? Even just a small step? The point is that such trend-bucking steps are not available to select from in the first place.
Galaxies “go against the trend” - they are temporary local decrease in entropy - if nothing could “go agianst the trend”, any interesting universe would never even have arisen from the original dispersion of matter and energy after the Big Bang.
Arguments about entropy are, in my opinion, extremely susceptible to faulty reasoning.
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Jurie
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posted 01. March 2004 20:19
Evan wrote: Arguments about entropy are, in my opinion, extremely susceptible to faulty reasoning.
I agree.
All the examples so far given from the non-biotic world, do not satisfy the last criterium, that of sustainability. Since life at least in one sense is a process that is executed by nano-machines, and those machines wear out, that by itself is not sustaining - there must also be a system whereby the process is able to replicate itself to ensure sustainability. Perhaps I did not use the correct word with sustainability; I specifically mean for the process to be able replicate itself, either self-replicate or with the help of another process, because that is the one thing that sets life apart from crystals, Benard convection cells and galaxies. Replication ensures sustainability in a way that overcomes the effects of the SLOT.
But the other point I am trying to establish, is that life processes are not the same as would be produced by the law of maximum entropy production. My argument is that life processes were not produced by the law of maximum entropy production, because I strongly suspect they violate that law. That is what I am trying to show with rabbit-world.
Taking galaxies for a moment, their formation is predictable from gravity. We are not surprised that they are there, given the initial conditions. And yes, there might be a local decrease in entropy, but isn't it so that no work is done against the trend, but quite the opposite, that it is rather the result of flowing with the trend? This example therefore does not satisfy the first (energy expense) nor third (sustainability) criteria.
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RBH
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posted 01. March 2004 22:21
Jurie wrote quote:
All the examples so far given from the non-biotic world, do not satisfy the last criterium, that of sustainability.
Not so. Do read Kauffman on self-organizing autocatalytic networks. As long as sufficient water flows ("as long as the means to do so is present") the water will continue to flow up and over the rocks. There's an FAQ on self-organizing systems here that covers some of that stuff.
Jurie also wrote quote:
Taking galaxies for a moment, their formation is predictable from gravity. We are not surprised that they are there, given the initial conditions.
Predictable from gravity only if there are minute discontinuities - irregularities - in the primeval soup following the big bang. Gravity alone does not predict galaxies or any other non-homogenous structure given a homogenous 'soup' of particles unless one invokes quantum fluctuations in densities of particles or some such source of inhomogeneity to get the coalescences into structures started. (And, incidentally, Jurie just gave the strong anthropic principle people a shudder with that "We are not surprised" line. ![[Smile]](smile.gif) They're glad he put in that "given the initial conditions" qualifier!)
I sympathize with the difficulty of what Jurie is trying to do. But it's real hard to make a "you can't there from here" argument in the state of partial knowledge we're in.
RBH
[ 01. March 2004, 22:30: Message edited by: RBH ]
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Jurie
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posted 01. March 2004 23:14
RBH wrote: quote:
As long as sufficient water flows ("as long as the means to do so is present") the water will continue to flow up and over the rocks.
I would liken the processes of life not to water flowing up and over a rock, but to water being pumped uphill. I am beginning to see the definition is being misunderstood, so I should sharpen it. What I mean by reducing entropy is that life processes "do hard work" to resist the flow; non-life processes merely go with the flow.
RBH wrote: quote:
There's an FAQ on self-organizing systems here that covers some of that stuff.
Thanks. I will work through the full FAQ; a brief glance told me I already know a lot of that stuff.
RBH wrote: quote:
They're glad he put in that "given the initial conditions" qualifier!
I have a working knowledge of BB theory; I didn't want to range far and wide, hence the terse qualifier. I included all you wrote and more in there.
RBH wrote: quote:
But it's real hard to make a "you can't there from here" argument in the state of partial knowledge we're in.
This sword cuts both ways. It's equally hard to argue that you CAN go there from here in our state of knowledge. As long as it is not obvious, and the knowledge is lacking, does not the burden of proof lie with those who say you can?
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The Pixie
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posted 02. March 2004 11:19
I would like to add a couple of point:
The "sustainable manner" is really just making reproduction a necessary requirement for life. This is not a unique insight, but does have a flaw: is a man still alive after a vasectomy, a woman after a hysterectomy; are worker ants alive?
The second point is that living things do not reduce entropy locally. On a day-to-day basis the entropy of a fully grown animal will remain pretty much the same (albeit fluctuating to some degree).
Pixie
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Jurie
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posted 02. March 2004 17:40
quote:
The "sustainable manner" is really just making reproduction a necessary requirement for life. This is not a unique insight, but does have a flaw: is a man still alive after a vasectomy, a woman after a hysterectomy; are worker ants alive?
Agreed; I also thought of that when testing the various versions of the definition.
The case of artificially sterile organisms such as a mule are really not the rule, but the exception - it is not the natural order. But they are certainly alive. These cases exhibit all the other characteristics of life, but lack sustainability. I'm not sure that exceptions disprove the rule.
The definition is limited, and singles out some defining characteristics of life (there are more than 100). I tried to find a definition that is overarching in the sense that the SLOT is overarching over all other laws. That is why the SLOT features strongly. It seems to me that life uniquely resists the trend of decay, not in the sense of Benard convection cells forming, which is really going with the flow, but in a way that goes against the flow. One of the problems I face is finding a suitable scientific term for "going against the flow." Decreasing entropy does not quite cut it.
Worker ants or bees: I tried to cover this case in two ways:
1. The definition of sustainability: "reproduction from the environment," the environment includes other processes.
2. The definition for locally: It must be understood that "process" is not necessarily equivalent to "organism." In many cases, the process can be limited to one organisms' boundary, but in a colony of ants the process extends to include the colony.
This is one of the reasons I avoided terms like "organism" and "life form" in favour of "process." Another reason is that using terms that themselves come from biology, puts you in danger of circularity. A third reason is that I did not necessarily want to exclude artificial life - that appeals strongly to the Intelligent Design aspect.
quote:
The second point is that living things do not reduce entropy locally. On a day-to-day basis the entropy of a fully grown animal will remain pretty much the same (albeit fluctuating to some degree).
True, I thought of that and tinkered with the definition. You will see that I used "can reduce" instead of "must reduce." But if you think of a plant growing from a seed, that is a very clear case were the process reduces local entropy by a whopping amount. And for a young rabbit growing up the same. In adulthood you are correct.
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Rex Kerr
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posted 02. March 2004 17:58
I'm confused about the concept of "going against the flow".
I am alive because--among other things--sugars that I ingest are broken down by various enzymes and converted into ATP, in a process that only occurs because each step in the process is energetically favorable (in the Gibbs free energy sense, which includes entropy).
Is this supposed to "go against the flow" or not?
If the answer is "yes", how much do I have to remove from the pathway until the answer becomes "no"? Or, if the answer is "no", how much do I have to add until it is "yes" (assuming that the answer for all reactions happening in an entire living organism is "yes")?
Even if there is no sharp dividing line, it would still be helpful to refine the classification of "with the flow" vs. "against the flow".
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Jurie
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posted 02. March 2004 19:32
quote:
I'm confused about the concept of "going against the flow".
...
Even if there is no sharp dividing line, it would still be helpful to refine the classification of "with the flow" vs. "against the flow".
This is one area where I need help with putting it in rigorous terms on which one might base a calculation. "Against the flow" is hopeless. I tried to use the term "avoiding the path of maximal entropy increase." At www.entropylaw.com I found a reference to "the law of maximal entropy increase"; I am not sure if this law is accepted wide enough for me to use. This law is an attempt to explain the formation of order in systems far from equilibrium, such as Benard cells. I strongly suspect that many life processes violate this law. If this is truly the case, and if this law holds for all non-life processes, then the definition for life would simplify to:
"Life is defined as any process which contains actions that violate the Law of Maximising Entropy."
Here is a small refining attempt:
"ability to decrease entropy" means the outcome of the process has the result that while local entropy is decreased, wider entropy is not increased along the maximising path; unlike non-life processes, where local entropy can decrease as a result of the system being far from equilibrium, going along the entropy maximising path, processes of life can decrease entropy in a way that violates the law of maximum entropy increase; (I need help to put this babble more rigorously)
quote:
Is this supposed to "go against the flow" or not?
I'm very glad you brought up ATP - it is one of the most clear examples of "going against the flow" that I could think of. I quote from www.nobel.se/chemistry/laureates/1997/press.html:
quote:
The most detailed studies of ATP synthase concern the F 1 part and how it functions. Boyer and co-workers clarified that the enzyme functions in a very particular way. They found that, as opposed to the view generally held, the step requiring energy was not the synthesis of ATP from ADP and inorganic phosphate, but that energy was required to bind ADP and the phosphate to the enzyme and to release ATP. Nevertheless an energy surplus was stored in the ATP. In this respect ATP synthase differs from the majority of all enzymes, which bind and release substrates and products spontaneously, but for which the overall catalytic reaction requires energy.
To me it is clear that the action of ATP synthase is not entropy maximising and is therefore "against the flow," since it captures free energy and stores it in a free form, instead of turning it into heat. Additionally, it can't work spontaneously if just put in a test tube like other enzymes can.
[ 02. March 2004, 20:57: Message edited by: Jurie ]
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The Pixie
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posted 03. March 2004 07:10
Jurie
quote:
True, I thought of that and tinkered with the definition. You will see that I used "can reduce" instead of "must reduce." But if you think of a plant growing from a seed, that is a very clear case were the process reduces local entropy by a whopping amount. And for a young rabbit growing up the same. In adulthood you are correct.
In fact growing increases entropy locally. Two kilograms of water has exactly twice the entropy of one kilogram of water at the same conditions. By the same token, a seed or baby rabbit has very little mass, so very low entropy compared with the tree or adult rabbit.
Perhaps counter-intuitively every time you eat something, you increase your total entropy, because you increase your mass. Eating hot food will be especially bad. As you metabolise the food, entropy is lost through radiated heat, and through loss of mass via exhalation and excretion.
I guess a better way would be to consider the entropy per unit mass, to avoid this problem. Even so I cannot see why a baby rabbit has either more or less entropy per unit mass that the adult rabbit. Indeed, I think this is what characterises living systems, that they maintain a "dynamic stasis"; a complex system of chemical reactions, but the entropy is kept more or less constant.
Pixie
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