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I think you've got a minority opinion calling crystals "alive," although it does jibe with one definition of life that I heard: "any self-sustaining system that

I think you've got a minority opinion calling crystals "alive," although it does jibe with one definition of life that I heard: "any self-sustaining system that reduces internal entropy."

DanBC 6y ago
Dawkins doesn't call crystal structures alive, but he does mention them as a potential hypothetical source for life. http://www.bbc.co.uk/earth/story/20160823-the-idea-that-life-began-as-clay-crystals-is-50-years-old http://www.bbc.co.uk/earth/story/20160823-the-idea-that-life... > Cairns-Smith found a more eager audience in science journalists and the popular press. Other scientists showed interest, too: the evolutionary biologist and writer Richard Dawkins discussed the crystals-as-genes hypothesis in his 1986 book The Blind Watchmaker. [...] > His aim was to find a system much simpler than modern life, but which had some of the crucial properties of a living system. He found an answer in an unlikely place: clays.
kevmo 6y ago
That's one place where my "What is Life?" college class landed.
adrian_b 6y ago
While obviously crystals are not alive, they satisfy more careless definitions of life that were sometimes encountered, i.e., when put in a "nutritive" solution, they are able to grow and reproduce themselves.
- beowulfey 6y ago
  I think even under that definition they don't truly reproduce and still aren't really life -- they don't create the same material they arise from for example (so not allowing for additional crystals to form). A non-renewing source of the material has a maximum amount of crystal that can grow, I would imagine. This is different than something like a virus, which carries the instructs to replicate itself and the ability to travel to new hosts to create more of itself (and still isn't really considered alive).
  - Ericson2314 6y ago
    > A non-renewing source of the material has a maximum amount of crystal that can grow So any biosphere that fails to escape its looming red giant was never alive? I'm not a "all abstractions leak" type of person, so I will choose my definitions very carefully, with funny choices about clays, crystals, virus, etc. as an acceptable causality.
- dekhn 6y ago
  This is just wrong (as you say, careless). The criteria is "metabolism", not growth and reproduction. Similarly, viruses are not alive although they can reproduce. Interestingly, there are some highly parasitic organisms with limited ability to metabolize, that is, they have lost their genes and instead depend on their host organism (but I think all those examples still have some level of metabolic capability).
  - Ericson2314 6y ago
    I don't really know what "metabolism" means, abstractly. I am deader than a virus without chloroplasts existing elsewhere. Viruses need a host for the productive bit, I had food for the non-reproductive bit. Viruses don't break down fast enough compared to their abundance to cause extinction, so why fault them for optimizing? People commonly theorize that virus came from rump parasitic cells. I wouldn't be surprised if at some point a huge virus with a membrane accidentally picked up enough stuff to become a cell again. To go back to chloroplasts again, it would be like how brown algae is an ex-heterotroph.
    - geomark 6y ago
      Metabolism has two parts: Catabolism breaks down complex molecules into smaller building block molecules - think proteins -> amino acids. Then anabolism uses those building blocks to build up larger molecules for growth and maintenance. Crystals don't do the catabolism part.
      - kubanczyk 6y ago
        Nah, this seems more like an implementation detail than an actual core of life's "functionality".
        BlueTemplar 6y ago
        Looks like cell's phospholipid bilayer is anabolized just like an "endothermic" crystal : no need to cross a potential barrier (and releases energy instead of consuming it)? On the other hand, other forms of anabolism require crossing an energy barrier (and consumes energy) ? While catabolysm is the inverse operation : crosses a barrier, but releases energy? The formation/destruction of "exothermic" crystals like dissolution of Sodium Hydroxide if put in contact with water is I guess similar to above two reactions ? (Or better example: explosives)
- Igelau 6y ago
  > obviously crystals are not alive Very few things are obvious. Is this?
Razengan 6y ago
> "any self-sustaining system that reduces internal entropy." Planet Earth would/should definitely count as alive, especially if it "reproduces" via us terraforming other planets to become like Earth.
- angst_ridden 6y ago
  There are plenty of conceptualizations of planet-as-organism, e.g., Gaia Hypothesis.
- whimsicalism 6y ago
  Ultimately, this is a semantic debate trying to apply human linguistic constructions to physical processes.
  - tw25508394 6y ago
    Amen! This is about as useful as debating whether Pluto is a planet.
  - dilawar 6y ago
    Good plot for Rick and Morty. Wait, they already did it.
- SuoDuanDao 6y ago
  It seems nonsensical in any case to claim something that contains life among its constituent parts is not itself alive. Plenty of organisms have 'dead' tissue as part of their gestalt and no one thinks of them as 'mostly' alive.
  - cossatot 6y ago
    Life isn't a constituent part of the Earth. It's a coating.
    - Razengan 6y ago
      That statement is such a gross oversimplification of a tiny fraction of the whole picture. Life permeates deep into Earth and even influences its geology: https://en.wikipedia.org/wiki/Kola_Superdeep_Borehole#Research https://en.wikipedia.org/wiki/Kola_Superdeep_Borehole#Resear... https://en.wikipedia.org/wiki/Petroleum https://en.wikipedia.org/wiki/Petroleum
api 6y ago
My favorite version of this classifies life as an exotic phase of matter in the sense of other exotic phases like Bose-Einstein condensates, etc. Life is a phase of matter in which the dynamics of information and Turing-complete computation overcome the ordinary dynamics of matter and energy. I am not aware of who originated this idea, but I heard it from Christoph Adami (a researcher in evolutionary information theory). I also recall someone at a conference proposing the term "Turium," for "Turing-complete phase of matter." Earth just happens to have an environment that contains a large abundance of this phase of matter, much like how stars are full of plasma etc.
- kubanczyk 6y ago
  How is this model useful? It certainly moves away from our domain knowledge and paints a new picture that is considerably more fuzzy than the old one. What do you gain by considering life in such way? Side note: computation seems like a wrong term, because it's not about counting/calculating/determining any abstract value, is it? A Turing-complete mechanism maybe?
  - api 6y ago
    I find the idea of it as a phase of matter very conceptually elegant in that it neatly classifies life as a unique but still physical phenomenon. Nevertheless I agree with you that the details of the definition are hard to pin down. Of course I have yet to see an attempted definition of life that isn’t a little squirrely or that isn’t just a list of criteria taken from the one example we have.
snowwrestler 6y ago
Crystals don’t reduce their internal entropy. They grow only on the interface with the media, and the portions of the crystal that become internal during this process do not change after crystallization if kept at constant temp and pressure. In contrast, if you put a plant and its media (soil, air, water) into constant temp and pressure, the plant will continue to grow and change until it exhausts the media. (assuming the temp and pressure are conducive to life) Ultimately plants become their own media by decomposing into soil.
- BlueTemplar 6y ago
  If an external disturbance scatters the atoms inside the crystal, they will snap back to the lattice again. In a way similar (up to a point) to "normal" living organism's homeostasis.

I think you've got a minority opinion calling crystals "alive," although it does jibe with one definition of life that I heard: "any self-sustaining system that reduces internal entropy."

DanBC 6y ago

Dawkins doesn't call crystal structures alive, but he does mention them as a potential hypothetical source for life. http://www.bbc.co.uk/earth/story/20160823-the-idea-that-life-began-as-clay-crystals-is-50-years-old http://www.bbc.co.uk/earth/story/20160823-the-idea-that-life... > Cairns-Smith found a more eager audience in science journalists and the popular press. Other scientists showed interest, too: the evolutionary biologist and writer Richard Dawkins discussed the crystals-as-genes hypothesis in his 1986 book The Blind Watchmaker. [...] > His aim was to find a system much simpler than modern life, but which had some of the crucial properties of a living system. He found an answer in an unlikely place: clays.

kevmo 6y ago

That's one place where my "What is Life?" college class landed.

adrian_b 6y ago

While obviously crystals are not alive, they satisfy more careless definitions of life that were sometimes encountered, i.e., when put in a "nutritive" solution, they are able to grow and reproduce themselves.

beowulfey 6y ago
I think even under that definition they don't truly reproduce and still aren't really life -- they don't create the same material they arise from for example (so not allowing for additional crystals to form). A non-renewing source of the material has a maximum amount of crystal that can grow, I would imagine. This is different than something like a virus, which carries the instructs to replicate itself and the ability to travel to new hosts to create more of itself (and still isn't really considered alive).
- Ericson2314 6y ago
  > A non-renewing source of the material has a maximum amount of crystal that can grow So any biosphere that fails to escape its looming red giant was never alive? I'm not a "all abstractions leak" type of person, so I will choose my definitions very carefully, with funny choices about clays, crystals, virus, etc. as an acceptable causality.
dekhn 6y ago
This is just wrong (as you say, careless). The criteria is "metabolism", not growth and reproduction. Similarly, viruses are not alive although they can reproduce. Interestingly, there are some highly parasitic organisms with limited ability to metabolize, that is, they have lost their genes and instead depend on their host organism (but I think all those examples still have some level of metabolic capability).
- Ericson2314 6y ago
  I don't really know what "metabolism" means, abstractly. I am deader than a virus without chloroplasts existing elsewhere. Viruses need a host for the productive bit, I had food for the non-reproductive bit. Viruses don't break down fast enough compared to their abundance to cause extinction, so why fault them for optimizing? People commonly theorize that virus came from rump parasitic cells. I wouldn't be surprised if at some point a huge virus with a membrane accidentally picked up enough stuff to become a cell again. To go back to chloroplasts again, it would be like how brown algae is an ex-heterotroph.
  - geomark 6y ago
    Metabolism has two parts: Catabolism breaks down complex molecules into smaller building block molecules - think proteins -> amino acids. Then anabolism uses those building blocks to build up larger molecules for growth and maintenance. Crystals don't do the catabolism part.
    - kubanczyk 6y ago
      Nah, this seems more like an implementation detail than an actual core of life's "functionality".
      - BlueTemplar 6y ago
        Looks like cell's phospholipid bilayer is anabolized just like an "endothermic" crystal : no need to cross a potential barrier (and releases energy instead of consuming it)? On the other hand, other forms of anabolism require crossing an energy barrier (and consumes energy) ? While catabolysm is the inverse operation : crosses a barrier, but releases energy? The formation/destruction of "exothermic" crystals like dissolution of Sodium Hydroxide if put in contact with water is I guess similar to above two reactions ? (Or better example: explosives)
Igelau 6y ago
> obviously crystals are not alive Very few things are obvious. Is this?

Razengan 6y ago

> "any self-sustaining system that reduces internal entropy." Planet Earth would/should definitely count as alive, especially if it "reproduces" via us terraforming other planets to become like Earth.

angst_ridden 6y ago
There are plenty of conceptualizations of planet-as-organism, e.g., Gaia Hypothesis.
whimsicalism 6y ago
Ultimately, this is a semantic debate trying to apply human linguistic constructions to physical processes.
- tw25508394 6y ago
  Amen! This is about as useful as debating whether Pluto is a planet.
- dilawar 6y ago
  Good plot for Rick and Morty. Wait, they already did it.
SuoDuanDao 6y ago
It seems nonsensical in any case to claim something that contains life among its constituent parts is not itself alive. Plenty of organisms have 'dead' tissue as part of their gestalt and no one thinks of them as 'mostly' alive.
- cossatot 6y ago
  Life isn't a constituent part of the Earth. It's a coating.
  - Razengan 6y ago
    That statement is such a gross oversimplification of a tiny fraction of the whole picture. Life permeates deep into Earth and even influences its geology: https://en.wikipedia.org/wiki/Kola_Superdeep_Borehole#Research https://en.wikipedia.org/wiki/Kola_Superdeep_Borehole#Resear... https://en.wikipedia.org/wiki/Petroleum https://en.wikipedia.org/wiki/Petroleum

api 6y ago

My favorite version of this classifies life as an exotic phase of matter in the sense of other exotic phases like Bose-Einstein condensates, etc. Life is a phase of matter in which the dynamics of information and Turing-complete computation overcome the ordinary dynamics of matter and energy. I am not aware of who originated this idea, but I heard it from Christoph Adami (a researcher in evolutionary information theory). I also recall someone at a conference proposing the term "Turium," for "Turing-complete phase of matter." Earth just happens to have an environment that contains a large abundance of this phase of matter, much like how stars are full of plasma etc.

kubanczyk 6y ago
How is this model useful? It certainly moves away from our domain knowledge and paints a new picture that is considerably more fuzzy than the old one. What do you gain by considering life in such way? Side note: computation seems like a wrong term, because it's not about counting/calculating/determining any abstract value, is it? A Turing-complete mechanism maybe?
- api 6y ago
  I find the idea of it as a phase of matter very conceptually elegant in that it neatly classifies life as a unique but still physical phenomenon. Nevertheless I agree with you that the details of the definition are hard to pin down. Of course I have yet to see an attempted definition of life that isn’t a little squirrely or that isn’t just a list of criteria taken from the one example we have.

snowwrestler 6y ago

Crystals don’t reduce their internal entropy. They grow only on the interface with the media, and the portions of the crystal that become internal during this process do not change after crystallization if kept at constant temp and pressure. In contrast, if you put a plant and its media (soil, air, water) into constant temp and pressure, the plant will continue to grow and change until it exhausts the media. (assuming the temp and pressure are conducive to life) Ultimately plants become their own media by decomposing into soil.

BlueTemplar 6y ago
If an external disturbance scatters the atoms inside the crystal, they will snap back to the lattice again. In a way similar (up to a point) to "normal" living organism's homeostasis.