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It's fair to characterize life as a process that locally decreases entropy. Non-living processes tend to increase entropy. Even if you have a rock that looks

It's fair to characterize life as a process that locally decreases entropy. Non-living processes tend to increase entropy. Even if you have a rock that looks exactly like a human being, say one of Phidias' statues, it will decay until it looks like every other rock given enough time and exposure to the elements. It rarely goes the other way around, the wind does not sculpt David out of marble. It's probably not a sufficient criterion for life, but it's at least necessary to avoid granting life to a wildfire or some other process most would not consider living.

wwarner 3y ago
All true, but equally important is that life is rapidly increasing entropy in a larger, but also local, frame. It’s like a fire. So, in a closed system, living things must exhaust their source of energy and reach equilibrium with its surroundings.
willis936 3y ago
It's certainly not a sufficient criterion. I argue nothing about my air conditioner is living and is no closer to living than any other rock.
- Cyphase 3y ago
  This isn't a fully formed point, just a thought.. but your air conditioner wouldn't exist without a living system directing matter to form an air conditioner; at least, it's so unlikely as to be practically impossible. So an air conditioner may not be a living system, but it's the product of a living system (at some point; maybe there are other non-living systems in the pipeline, e.g. factory robots).
  - willis936 3y ago
    I don't understand a heat pump to be an inherently artificial thing, but I am struggling to think of an example of a naturally occurring heat pump. If there were natural valves and compressors (which there might be from certain perspectives) then I could see a naturally occurring heat pump being possible. It seems strange to say process devices are the thing that make a system living or not.
fluoridation 3y ago
>Even if you have a rock that looks exactly like a human being, say one of Phidias' statues, it will decay until it looks like every other rock given enough time and exposure to the elements. The same is true of living things. Given enough time, anything living is reduced to a pile of oxides. Some physical processes decrease entropy locally, sometimes by incredible amounts. That's how we have the sun. What we really take from the sun is not energy, but its stored negative entropy; energy is just the medium to move it around.
- marginalia_nu 3y ago
  Right, but it must be granted that the moment of death is a point where this decay accelerates greatly.
  - fluoridation 3y ago
    But qualifying any particular moment as "death" already implies that we've granted the thing in question the quality of being alive at some point, so it's not a useful way to distinguish living from non-living.
    - marginalia_nu 3y ago
      But that is how we talk about living things. A man is alive, has a fatal heart attack, then he is not alive. I don't think anyone would argue he was never alive, or is still alive after having gone cold. Studying this transition from life to non-life, or vice versa should be most informative in distinguishing the two states.
      - fluoridation 3y ago
        Sure, but the question is not about distinguishing living from dead things, but about distinguishing currently and formerly living things from things that were never alive. More specifically, about distinguishing them structurally, not comparatively. If "death" is the point where the decay into entropy of something greatly accelerates then hypothetically we could say a rock "dies" when it's melted, or alternatively we could say that it doesn't "die" because it was never alive. The distinction does not lie on the thing itself, but on which things we assign the property of being able to "die".
cma 3y ago
Definitely not a sufficient criterion. A solar panel that charges a capacitor would be alive.
- jvan 3y ago
  Why not consider it alive? The same with the fires mentioned in other comments. In The Andromeda Strain (the novel, don't remember if it's in the film as well), there's a scene where the characters are trying to determine a single quality they can look for that signifies life. They come up with energy conversion, and they do consider luminescent watch hands and geologic formations. It's been a long time since I read it, I don't recall them ending with back-patting and "mission accomplished" cheers, but the point of the scene wasn't to make a definite answer for the readers nor the characters - it was that when you're looking for life, perhaps your definition of "life" will need expanded. So why do we need a definition that absolutely includes This, and absolutely excludes That and The Other? What if we settle on a definition and found out it does apply to The Other, why must we change the definition instead of changing how we categorize The Other? Both are adjusting our model to fit new evidence. Why be so determined that Life Must Be Like Us And No Other?
  - pixl97 3y ago
    Generally with life we require some form of replication or it would quickly go extinct. Now, if you add in a 3D printer/assembler to the aforementioned solar-panel/battery the loop is getting rather complete for something to be considered life.
    - jvan 3y ago
      99% of mules are sterile. And I'm not sure what the current debate on viruses and prions is. It's a difficult question to generalize.
      - pixl97 3y ago
        Oh, for sure. Like worker bees and ants, they don't breed themselves, but feed the collective that does. I guess one of the rules of life will be "It's not an object, it's a system"
visarga 3y ago
> It's fair to characterize life as a process that locally decreases entropy I would characterise life as a process that copies its information into the future. Maybe the idea of copying and that of decreasing entropy are closely related. It's interesting that life needs digital codes to evolve, they seem a requirement for both maintaining low entropy and copying.

wwarner 3y ago

All true, but equally important is that life is rapidly increasing entropy in a larger, but also local, frame. It’s like a fire. So, in a closed system, living things must exhaust their source of energy and reach equilibrium with its surroundings.

willis936 3y ago

It's certainly not a sufficient criterion. I argue nothing about my air conditioner is living and is no closer to living than any other rock.

Cyphase 3y ago
This isn't a fully formed point, just a thought.. but your air conditioner wouldn't exist without a living system directing matter to form an air conditioner; at least, it's so unlikely as to be practically impossible. So an air conditioner may not be a living system, but it's the product of a living system (at some point; maybe there are other non-living systems in the pipeline, e.g. factory robots).
- willis936 3y ago
  I don't understand a heat pump to be an inherently artificial thing, but I am struggling to think of an example of a naturally occurring heat pump. If there were natural valves and compressors (which there might be from certain perspectives) then I could see a naturally occurring heat pump being possible. It seems strange to say process devices are the thing that make a system living or not.

fluoridation 3y ago

>Even if you have a rock that looks exactly like a human being, say one of Phidias' statues, it will decay until it looks like every other rock given enough time and exposure to the elements. The same is true of living things. Given enough time, anything living is reduced to a pile of oxides. Some physical processes decrease entropy locally, sometimes by incredible amounts. That's how we have the sun. What we really take from the sun is not energy, but its stored negative entropy; energy is just the medium to move it around.

marginalia_nu 3y ago
Right, but it must be granted that the moment of death is a point where this decay accelerates greatly.
- fluoridation 3y ago
  But qualifying any particular moment as "death" already implies that we've granted the thing in question the quality of being alive at some point, so it's not a useful way to distinguish living from non-living.
  - marginalia_nu 3y ago
    But that is how we talk about living things. A man is alive, has a fatal heart attack, then he is not alive. I don't think anyone would argue he was never alive, or is still alive after having gone cold. Studying this transition from life to non-life, or vice versa should be most informative in distinguishing the two states.
    - fluoridation 3y ago
      Sure, but the question is not about distinguishing living from dead things, but about distinguishing currently and formerly living things from things that were never alive. More specifically, about distinguishing them structurally, not comparatively. If "death" is the point where the decay into entropy of something greatly accelerates then hypothetically we could say a rock "dies" when it's melted, or alternatively we could say that it doesn't "die" because it was never alive. The distinction does not lie on the thing itself, but on which things we assign the property of being able to "die".

cma 3y ago

Definitely not a sufficient criterion. A solar panel that charges a capacitor would be alive.

jvan 3y ago
Why not consider it alive? The same with the fires mentioned in other comments. In The Andromeda Strain (the novel, don't remember if it's in the film as well), there's a scene where the characters are trying to determine a single quality they can look for that signifies life. They come up with energy conversion, and they do consider luminescent watch hands and geologic formations. It's been a long time since I read it, I don't recall them ending with back-patting and "mission accomplished" cheers, but the point of the scene wasn't to make a definite answer for the readers nor the characters - it was that when you're looking for life, perhaps your definition of "life" will need expanded. So why do we need a definition that absolutely includes This, and absolutely excludes That and The Other? What if we settle on a definition and found out it does apply to The Other, why must we change the definition instead of changing how we categorize The Other? Both are adjusting our model to fit new evidence. Why be so determined that Life Must Be Like Us And No Other?
- pixl97 3y ago
  Generally with life we require some form of replication or it would quickly go extinct. Now, if you add in a 3D printer/assembler to the aforementioned solar-panel/battery the loop is getting rather complete for something to be considered life.
  - jvan 3y ago
    99% of mules are sterile. And I'm not sure what the current debate on viruses and prions is. It's a difficult question to generalize.
    - pixl97 3y ago
      Oh, for sure. Like worker bees and ants, they don't breed themselves, but feed the collective that does. I guess one of the rules of life will be "It's not an object, it's a system"

visarga 3y ago

> It's fair to characterize life as a process that locally decreases entropy I would characterise life as a process that copies its information into the future. Maybe the idea of copying and that of decreasing entropy are closely related. It's interesting that life needs digital codes to evolve, they seem a requirement for both maintaining low entropy and copying.