[cossatot]

The crystal thing is throwing me (a geologist) off. Basically all Earth materials are crystalline. So rocks are alive (colonial organisms I guess since they are aggregates of crystalline minerals) but the magma that they crystallize from is not alive? Or is magma alive too? What about obsidian, which is glass but compositionally identical to a crystalline igneous rock. No crystals! The Earth's crust and mantle: Crystalline. Alive. The Earth's outer core: liquid iron and nickel. Non-living. The inner core: crystalline iron and nickel. Alive.

Crystallization is reversible in a thermodynamic sense. You take some granite, melt it, and then cool it (slowly, under pressure), and you have granite again. Is this a phoenix/Jesus-like life and death cycle? Or does life only change forms?

I agree with you generally that 'life' may be gradational. However I think calling crystals 'life' actually removes any meaning whatsoever from the term. If the line isn't somewhere in the neighborhood of viruses and prions then it kinda has to expand to include anything made of matter (and then energy etc.).

While we don't (and don't have to) have a precise definition of 'life', the 'life' gradation needs to branch like a Bezier curve off the x axis at some point for it to be a functional term.

[andrewflnr]

Playing devil's advocate: "crystalline" in bulk is different from "a crystal". I think the idea is that individual crystals are "alive" in that sense, and the bulk is maybe a colonial organism. Maybe quartz crystals forming in a chunk of what will soon be granite are only "alive" in the brief period where they are still growing. When the rock solidifies, the crystal "starves" and "dies", leaving only a corpse. Melting and refreezing granite would basically be composting, using formerly alive material to foster new life.

On a similar note, a dead human is "compositionally identical" to a living one, at least for a little while, so I think that's entirely a red herring. :)

[BlueTemplar]

Interesting parallel, after all crystals release energy in the form of heat while forming!

Edit : forgot about crystals that absorb energy while forming:

https://news.ycombinator.com/item?id=25516072

[BlueTemplar]

> the 'life' gradation needs to branch like a Bezier curve off the x axis at some point for it to be a functional term.

What do you mean? Bezier curves are 2d parametric curves, the x and y axes are completely arbitrary...

[6510]

As the ancients knew: All facts require an observer so life is what can be convincingly be identified as life by a human being.

[narag]

Is key word "alive" or is it "conscious"? Or at least "sentient"?

[whatshisface]

Crystals are mostly not sentient, except for quartz. The high prevalence of quartz in the Earth's crust can be explained by the anthropic principle.