Ideas: Non-carbon based lifeforms

[nedjer]

As far as I know there's no definite example of a real non-carbon lifeform, but it's theoretically possible. So that's got me thinking about how a calcium, sulphur, silicon . . . lifeform might operate in-game.

Silicon might be able to infiltrate chips or move through stone or turn to sand, but would it 'hold-up'/ function at all in an oxygen based environment? Are some chemical bases when mixed with oxygen simply going to disintegrate/ burn out?

I'm held back here by an almost total ignorance of chemistry, but could you have an acid-based lifeform or an alkaline 'chalk' calcite? The former would be distinct from a movie Alien in that Aliens process acid. as do our stomachs, but they're not made of acid . . ?

For fantasy this might offer up some weird properties/ monsters without going all scientific in a magic world; in SciFi it'd be good to be a bit more clued up.

 

[ggroy]

For something possibly analogous to carbon-based life, it could be based on the equivalent of "organic" molecules and water. Lifeforms could be drastically different if they were made out of something that wasn't based in principle on "organic" style molecules.

If one wants to go even further, this can involve changing chemistry altogether at the atomic level. (ie. What happens if the fine structure constant has a significantly different value).

 

[Nagol]

Hypothetical types of biochemistry - Wikipedia, the free encyclopedia

 

[UngainlyTitan]

I would reccomend Hal Clement's Iceworld, the main character is a sulphur based organism. It's a good read and pretty well thought out.

 

[JustKim]

I'm held back here by an almost total ignorance of chemistry, but could you have an acid-based lifeform or an alkaline 'chalk' calcite? The former would be distinct from a movie Alien in that Aliens process acid. as do our stomachs, but they're not made of acid . . ?

As far as the science goes, no, you couldn't have acid-based life forms. When talking about life forms composed of carbon, or silicon, or sulfur, the criteria there is the most versatile element possible because you need a large variety of interchangeable chemical bonds to form structures and power biological processes.

Acids are neither an element (they're a compound), nor are they versatile- they typically react in one way, which is to dissolve. That's what qualifies them as acids by most scientific definitions.

In terms of chemical interactivity, carbons are Legos and acids are Shrinky Dinks (and silicons are Duplos and sulfurs are Barrel of Monkeys).

It is perfectly possible to have an acid as the solvent of a life form, by replacing water, but you wouldn't call that acid-based any more than you would call us water-based. There are also fewer molecules that could interact in an acidic medium, but then that's true of every theoretical basis for life. In theory you will always be talking about less complex, less efficient life forms with any alternative to carbon. On the other hand, if carbon-based life on earth had not been massively poisoned with oxygen so long ago, we would not be in a position to speculate on the complexity or efficiency of other life forms either.

Anyway, I hope that helps give you an idea of the chemistry behind the building blocks of life.

 

[Umbran]

Silicon might be able to infiltrate chips or move through stone or turn to sand

Look, you're a carbon based life form, right? Does that mean you can move through coal, or turn into a shower of diamonds or graphite flakes? No? Well, then don't expect that kind of behavior from other bases for life, unless magic is involved.

When discussing other chemical underpinnings for life, you are usually still talking about having some complex molecules, in some kind of fluid-filled bubble, making something analogous to a cell. Silicon-based life forms don't look like rocks - they look like life forms. You probably cannot tell the chemical basis from gross physical appearance.

Having strong acids or bases as the solvent in the cell is a bad idea - whatever your chemical basis is, strong acids and basis will do nasty things to your complex molecules. You might have atmospheres or oceans that are somewhat acidic or basic, mind you, but you have to go some way to figure out how stable systems of complex molecules developed in highly oxidative or reductive environments.

The biggest issues are how these critters with other basis manage to share environments. Having a silicon basis doesn't mean you eat rock, any more than being carbon based means we drink crude oil. Your silicon-based monster cannot eat carbon-based life forms and expect to get its require nutrients.

 

[nedjer]

turn into a shower of diamonds

All my PCs need to be able to this now

 

[nedjer]

As far as the science goes, no, you couldn't have acid-based life forms. When talking about life forms composed of carbon, or silicon, or sulfur, the criteria there is the most versatile element possible because you need a large variety of interchangeable chemical bonds to form structures and power biological processes.

Acids are neither an element (they're a compound), nor are they versatile- they typically react in one way, which is to dissolve. That's what qualifies them as acids by most scientific definitions.

In terms of chemical interactivity, carbons are Legos and acids are Shrinky Dinks (and silicons are Duplos and sulfurs are Barrel of Monkeys).

It is perfectly possible to have an acid as the solvent of a life form, by replacing water, but you wouldn't call that acid-based any more than you would call us water-based. There are also fewer molecules that could interact in an acidic medium, but then that's true of every theoretical basis for life. In theory you will always be talking about less complex, less efficient life forms with any alternative to carbon. On the other hand, if carbon-based life on earth had not been massively poisoned with oxygen so long ago, we would not be in a position to speculate on the complexity or efficiency of other life forms either.

Anyway, I hope that helps give you an idea of the chemistry behind the building blocks of life.

So, basically, if I want to be remotely 'real world' for SciFi I need stick to metabolising chemicals rather than made of chemicals.

 

[UngainlyTitan]

So, basically, if I want to be remotely 'real world' for SciFi I need stick to metabolising chemicals rather than made of chemicals.

real world living things are made of chemicals. Basically they are made of cells, which are bag of fatty membranes (made of lipids, which are long chain fat polymers), containing a soup of proteins,fats, RNA and other micro-structures which are in turn more bundles of protein etc and sometimes DNA) Pretty much all of which are long chain organic molecules of one sort or the other.
So they both metabolize chemicals and are made of them.

the key to thin are proteins which are complex tri-dimensional structures and owe this to carbons ability to bond in multiple orientations. In principle any other atom in the same group in the Periodic table exhibits similar chemistry, so you could replace carbon with silicon.

 

[NewJeffCT]

Of course a silicon based lifeform would work -

just don't go smashing their eggs!