Life Maintains Itself
Life Maintains ItselfFrom DefinitionOfLife
We cannot say that the replication of a human being can maintain the internal order of this particular human being.
Why not? Isn't making a back-up of a CD a way of maintaining its content? Nobody said anything about maintaining the order in the place that it is.
We're trying to find a good definition of life that covers the common-sense idea of "alive". One candidate was something like "If it can replicate, it is alive". After some discussion, this was seen as inadequate because (1) sterile humans, mules and other sterile hybrids, and certain other things cannot replicate, yet are instinctively seen as alive, while (2) some sorts of replicators -- crystals, fire, memes, songs (including bird songs), knock-knock jokes, chain reactions, etc. -- are instinctively seen as not alive.
But while replication is neither a necessary nor sufficient condition for something being alive, it is a commonly used mechanism in life's maintenance of itself.
on Maintaining Order:
Maintaining order implies that the system prevents random information in the environment from flowing in and replacing the core information in the system. Feedback and replication are two mechanisms to achieve this. We live on three levels -- in our brains, in our cells, and in our DNA.
Surrounded by random processes, an animal's brain prevents its core information (thought) from being replaced by random information. Brain cells probably rely on feedback like computer memory. When the system fails, random information flows in, and the "thought" that was preserved is gone; forever overwritten by random information.
Even living organisms without brains (e.g. bacteria) are alive, as are the individual cells in a human body. Each cell or bacterium is its own system, preserving order in a sea of random information. When the cell dies, random processes begin to deteriorate the cell walls and eventually, the cell is no longer recognizable.
DNA preserves information too, but over a longer period of time. An animal species may not fit the definition of a "system" used here. Some of the oldest information on Earth is stored in DNA; DNA for many animals that shared a history only millions of years ago still contain some of the same DNA.
My two cents: I think the important property of living things is the self-organizing property. In other words, a system is "alive" to the extent that it has anti-entropic properties. A system is "alive" to the extent that it reorganizes itself to stave off the effects of entropy. By this definition, a rock is not very alive, while all the biological things we think of as living are extremely alive. If you consider a really old person whose system is starting to fail, and may shortly die--then you see a system which is losing the battle against entropy. When "death" occurs the system will no longer reorganize itself and entropy will quickly wreck whats left of the system...
Ripples, fire, blah blah blah blah ...
Are memes alive? see MemesShmemes
As pointed out below in why viruses are arguably not alive, vitrified humans are parasitic. It isn't their bodies that maintains their structure, it's the refrigerator. And the refrigerator isn't alive because it doesn't maintain its own structure.
[carbon atoms only passively maintain their structure and this sneaking attempt to make an analogy between the alive and the dead is summarily deleted]
So it seems that neither your body nor the fridge maintain their own structure. Both are dependent on interaction with their environment to do that.
The fact that I don't do something by myself, or that I can only do it within certain conditions, doesn't prove that I don't do it at all. The human body actively maintains its own structure in a suitable environment; it's obvious that it isn't the environment that's performing that task. In contrast, the fridge never does anything to maintain its own structure; the environment does far more for the fridge than the fridge does for itself.
The genome of a virus, once spliced into a host organism's replicative machinery, does not maintain its internal structure. It's merely replicated. Recombine it, and it doesn't raise a finger to stop you; inside a cell it's quite thoroughly dead.
Isn't making copies of a structure a particular mechanism for preserving it?
Sure. And I have here some live influenza viruses and some dead ones. Which would you prefer me to inject? The dead ones will inoculate you. The live ones will kill you. If you don't think the live ones qualify as "life", then you won't mind which I use, will you?
That's quite possibly just expression, as with light bulbs. I'd rather drink water than poison, or be attacked by a non-functioning battlebot than a working one, but that doesn't impact their status.
In what way does a biosphere not maintain its internal structure? Ice ages come, and it adapts. Oceans rise, and it adapts. What else does it do but maintain its internal structure?
If you believe in Gaia then to the extent you believe it the Earth is alive.
I don't believe in Gaia. I observe a biosphere, and I observe your assertion at the top of the page that a biosphere is not alive. Please answer the question.
Then obviously you don't believe that our biosphere has "enough" homeostatic systems to qualify as alive. Besides, it isn't alive since there are as many self-reinforcing loops in the biosphere as there are homeostatic systems. It's just chance that there are any homeostatic systems. In particular, the biosphere doesn't resist ice ages, it creates them.
Laser beams, black holes and ripples in a pond do not have any structure to maintain any more than fire does. Laser beams in particular only look like they have structure because the laser is constantly emitting identical short pulses. The beam is no more maintaining its structure than a flight of bullets do. Laser beams do dissipate after a certain distance even in empty space. Black holes have even less structure than the sun does and are not using energy to maintain that structure. Ripples in a pond are not maintained either. They're created then they fade away. The only way to maintain ripples would be to create new ripples. And in that case, it's certainly not the ripples that are creating the new ripples so they're not maintaining themselves. Now, solitons are localized waves which maintain their coherency for a very long time. However, they are not maintained actively by the usage of energy but passively by coincidences in their environment.
The only way to maintain ripples is for something else to create new ripples.
(sorry, but there is nothing in the definition that supports that -- nb)
Ripples in a pond move away and dissipate. It only seems like there's a single system of ripples if you constantly create identical ripples to replace the past ones. So it's the same case as a flight of bullets. This isn't derived from the definition, just observation.
But the definition doesn't require constant maintenance. It just requires active one. And no, we cannot change the definition so that it would require permanent active structures, because we know from our experience that alive can be made dead.
The definition requires maintenance in the event of a disruption, or at least in the event of certain minimal disruptions - that's after all the definition of homeostasis. When you cut yourself, it heals over. Do anything to a ripple and it will never recover. They just glide along until they dissipate.
Not so. I took a knife and cut a ripple. It healed. Anything I can do to a ripple only propagates its structure. And ripples never dissipate - every time I go back to the pond, that's what I see - more ripples. Astonishing vitality by your definition!
If you actually damaged a ripple, it wouldn't fix itself. And something else is making the ripples, not ripples themselves. There is always text on wiki pages, but the letters aren't breeding.
Something else made life, unless you believe that life began at the big bang. Kill all the life on Earth and life won't heal itself. Something else would have to start it (again).
That's not relevant - life has to maintain itself in the event of certain size disruptions, that doesn't mean it can't be overwhelmed and destroyed. And ripples are simply not complex enough to qualify as life, as discussed on LifeIsComplex.
LifeIsComplex is not convincing.
False. if evolution as we define it were indeed the way things came to be, then life on the planet WOULD reappear, maybe 2 billion years later, but it would, just because earth is a suitable environment for life.. now the second problemis will the earth have a stable enough environment for the following 2 billion years to let life come about again. Now for the ripples... how often do you see ripples in your glass of water if you aren't shaking the glass?
Moved from DefinitionOfLife.
BlackHat: Planetary Weather
BlackHat: Weather has a lot more structure than fire. But it doesn't retain that structure as it is displaced. Nor does it propagate, let alone reproduce. For this reason, weather systems also do not evolve in the evolutionary sense.
YellowHat: Weather is not alive by the definition on this page because it's simply not a complex enough system. A tornado is certainly an example of a thermodynamic system which retains its internal function. But it's simply not complex enough. A tornado is probably equivalent in complexity to a prion, which nobody considers alive.
YellowHat: No, it does NOT in fact use energy to maintain the order integral to its internal function. Weather doesn't use energy to maintain itself. Rather, LAND and ATMOSPHERE and WATER use energy to maintain IT. So weather is no more alive than a CD being copied by human beings. And in any case, the weather of the entire planet is not a conserved structure anymore than the aurora borealis.
BlackHat: You might as well argue that people aren't alive because nucleic acids, proteins, carbohydrates and lipids use energy to maintain people. The issue of planetary weather being a "conserved structure" or not is moot, since this doesn't enter into the definition under discussion.
YellowHat: No, in fact you CANNOT argue that. Organelles use energy but individual nucleic acids, carbohydrates and lipids certainly DO NOT. Even individual proteins rarely use ATP (energy) in the human body. And even if it were true that all these bloody things use energy, it wouldn't detract from the fact that human bodies use energy to maintain themselves since human bodies are MADE UP of these things. Which certainly is not the case with weather since weather is determined by things OTHER than weather.
BlackHat: They do use all use energy, but it is usually thermodynamic energy rather than chemical energy. In any case it doesn't matter because the definition specifies that it is the order that must be maintained as the order in weather clearly is maintained (otherwise there would be no reason to try to model weather). There is no mention in the definition of a requirement that component parts be maintained. This requirement cannot be in a definition of life since again, people would then fail the definition as there are no component parts in people that are maintained - they are all exchanged, recycled and resynthesized (fortunately for people).
YellowHat: You just don't get it, do you? The order doesn't just have to be maintained, but has to be maintained BY THE SYSTEM ITSELF. Planetary weather is not maintained by itself. It's maintained by outside forces like land and water masses. And it's not as if this were a subtle or obscure point either since it's got a whole page devoted to it: LifeMaintainsItself.
BlackHat: Land and water masses aren't forces, simply environmental components, just like the food a person eats and the air a person breathes and the water a person drinks.
YellowHat: It doesn't matter what you call them. Call them your mystical fairies for all I give a damn about them. What matters is that land and water masses almost entirely determine stable weather patterns. Whereas food determines absolutely nothing.
BlackHat: Embarrassingly enough for the definition, if this was truly the objection, the land surfaces and water masses could simply be included in "weather". The whole package is still A complex system [that] uses energy to maintain the order integral to its internal function.
YellowHat: Why is it that I have to deal with morons? The fact that land and water masses aren't included isn't the objection. The objection is that the pattern of land and water masses is only RETAINED and not MAINTAINED.
YellowHat: Further, the issue of conserved structure is ENTIRELY within the scope of the definition of this page. If you're too much of an idiot to read these pages and understand how it falls into it, then you really shouldn't contribute to them.
BlackHat: The definition speaks of "order" which weather clearly maintains. In any event planetary-scale weather also has conserved structure.
YellowHat: Planetary weather doesn't maintain order, only RETAINS it.
BlackHat: Wrong. The difference between retaining and maintaining is that retaining is unstable to perturbation while maintaining is stable to perturbation. Planetary weather is clearly stable to perturbation.
YellowHat: Retain means something else creates it. Maintain means that the system itself creates it. Life maintains ITSELF. Weather retains the patterns created for IT. If those patterns are stable over time then this is entirely irrelevant. It means merely that those things which create the patterns (land and water masses) are themselves either retained or maintained. As it happens, the patterns of land and water masses are RETAINED over short periods of time. And when those patterns change, planetary weather is changed utterly.
BlueHat: We can see that BlackHat very well knows that weather is not alive; otherwise he couldn't argue along the border so well. But other points make it clear that it is not obvious that weather is not alive by the above definition; otherwise the YellowHat would have a much harder time counter-arguing.
YellowHat: Speak for yourself. There's nothing difficult about the difference between actively maintaining something and passively retaining it.
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