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I know we've got a lot of scientists in this community, so I hope you can help me out here. I'm trying to do a little partially-scholarly research for a story I'm cooking up that may or may not involve theories regarding silicon-based life forms (or, at least, non-carbon-based life forms). Basically I've been trying to find out how different, if at all, a silicon-based creature would be compared to a carbon-based creature.

What I know so far is that silicon has similar properties to carbon, but that it does not easily form the kinds of complex molecules that are present in carbon-based life. I've read arguments that, at higher temperatures and pressures, silicon may be able to work as such, but the arguments seemed a little speculative, so I don't know how much stock to put in an idea like that. The research of Dr. Gold has come up, and I'm going to look for his book to see what it says.

I thought of making this a question for Reasoned Cognition (and you can use it if you want, Kolter), but I also thought this might make for an interesting discussion with the whole gang, too.

... And, please, folks, bear in mind that that joke you're thinking of about silicone-based life has already been done to death.

Thanks,
Glarryg

could an ai be considered a silicon based lifeform?

A complex silicon lifeform would be so different that I don't know that Science could actually give you an answer here. At best it could give you some parameters to go on.

Your silicon based lifeform will likely still have formed with and alongside water, being a common chemical, and knowing that most chemistry works best in a liquid medium.

It must take in energy in some manner. For anything quick minded and quick of limb, it will probably be eating. Unless you encounter it in a vey hot (VERY hot - not habitable for humans hot) type world and give it some means of converting heat into other energy (maybe a natural steam engine!)

It may or may not excrete. We humans do because we are wasteful and poorly designed.

It may not communicate in any way we can understand. That includes sounds, although it's more likely to make noises of some kind, it's not at all likely to have any means to make OUR noises. Try to make the noise of a cricket. You don't have the parts to do it.

Think of some others?

If I remember right, the dragons in the Pern series were supposed to be boron based. It was a stretch.

The thing is, and bear with me because I'm trying to dredge up high school chemistry, carbon is optimal for bonding, isn't it? It means you can get really complex chains of the stuff, and therefore more variety. So it's a VERY good building block. It's what makes it so good as a basis for life. I just remember all those little diagrams of carbon atoms with bonds on all four sides.

My memory ends there. Oooh high school chemistry, how you have faded.

I remember little enough about my highschool bio courses (the teacher was psychotic, so there may be some repression going on) so all I really have to add is 'go you' for actually doing research on this kind of thing. I know I'd be too lazy to put that much effort into it...

And when I first saw the topic title, I thought this was somehow a thread about the episode of Star Trek with the Horta... anyone know how many geek-points that's worth?
It happened on Star Trek, it must be possible!

ManyWorlds wrote:And when I first saw the topic title, I thought this was somehow a thread about the episode of Star Trek with the Horta... anyone know how many geek-points that's worth?
It happened on Star Trek, it must be possible!

37.... And so did I.

I remember a documentary devoted entirely to scientists speculating about what alien life forms might be like... basically the only things they could agree on were: if it's alive it would use energy to reproduce or in some form, and if it's intelligent it would probably have a means to communicate with others of its kind and a means of moving around.

They also said it would probably be symetrical just because that makes moving around easier... although I know some crabs that would disagree.

TRI wrote:

ManyWorlds wrote:And when I first saw the topic title, I thought this was somehow a thread about the episode of Star Trek with the Horta... anyone know how many geek-points that's worth?
It happened on Star Trek, it must be possible!

37.... And so did I.

fools. you forgot the Tholians!!

Well, silicon is kinda similar to carbon: both are nonmetals, from the same group, both tend to form 4 chemical bonds.
Silicon also forms chains, silicones are an example.

Carbon is active, but silicon is quite inert chemically, so it'd need a good deal of temperature to match carbon's qualities.

One theory is a silicon based life form would look like 400 degrees celsius hot mushroom bathing in lava.
Though, the Mycon aren't completly silicon based, I think they're meant to be mostly carbon, mixed with silicon for protection.

Anyways, I think you should check chemical properties of silicon in high temperatures, perhaps it'd give clues.

Wikipedia to the rescue!
Giving it quick read, it turns out water and silicone life most likely doesn't mix. They'd most likely live in sulphur acid.

Don't forget also that anything that evolves on another planet would looking nothing like us. Eyes and noses and mouths and ears and so forth in those arrangements and those forms would not exist in an alien life form, because to have such features would mean it had to evolve on Earth because that is how 'animals' work here. They would have different requirements on different planets, so their bodies and structures would evolve differently.

Basically, this means that all of those science fiction stories and movies showing aliens are completely illogical and implausible for this very reason.

I do wish I knew the name of the scientist who I am taking this information from, but I couldn't tell you in a pink fit, sorry.

Dutch! wrote:Don't forget also that anything that evolves on another planet would looking nothing like us. Eyes and noses and mouths and ears and so forth in those arrangements and those forms would not exist in an alien life form, because to have such features would mean it had to evolve on Earth because that is how 'animals' work here. They would have different requirements on different planets, so their bodies and structures would evolve differently.

Basically, this means that all of those science fiction stories and movies showing aliens are completely illogical and implausible for this very reason.

I do wish I knew the name of the scientist who I am taking this information from, but I couldn't tell you in a pink fit, sorry.

not necessarily. There is this idea of paralell evolution. Basicly, you are going to get humanoid sahpes in higher lifeforms, develope similar, though not identical, characteristics in similar environments.

In theory, since things evolve a certain way based on environmental pressure and niche, and because the laws of physics are immutable(no 40 foot tall spiders, they don't work) if the two planets are similar enough, they are going to produce similar shapes.

You may get four arms, or more eyes, but you will still probably have recognisable arms. And, in addition, it is likely that any intelligent life we meet will have opposable thumbs. Can't do much in building recognizable technology without it.

Crab people!

Mr.Bob wrote:Crab people!

Craaaaaab People, Craaaaaab People...

Mr.Bob wrote:Crab people!

And dinosaurs with sticks!

- Joel Fagin

grabmygoblin wrote:

TRI wrote:

ManyWorlds wrote:And when I first saw the topic title, I thought this was somehow a thread about the episode of Star Trek with the Horta... anyone know how many geek-points that's worth?
It happened on Star Trek, it must be possible!

37.... And so did I.

fools. you forgot the Tholians!!

Dammit Goblin, I'm a part-time fan, not a Trekkie!

dracomax wrote:And, in addition, it is likely that any intelligent life we meet will have opposable thumbs. Can't do much in building recognizable technology without it.

I dunno, I can think of at least one arrangement (sticky-pad things) that would make opposable thumbs at least less-necessary.

Parallel evolution generally requires similar conditions. If it's to be a silicon based lifeform and needs high temperatures for the silicon to be chemically active, then that is not similar to Earth.

And the thumb is hardly required - I have a friend who through the luck of the draw was born with three fingers, not five, and in an odd configuration - he doesn't have a thumb per say on that hand, and he manages to write, grasp, and throw frisbees just fine with that configuration. There are plenty of configurations that don't require thumbs.

I'm getting a book on xenobiology soon, but I don't think I'll have it until like Thanksgiving. If you're still interested by then I can tell you what I've read I suppose.

Edit: I meant to say--Whoever linked the Star Control II thing: That game looks Bad Ass. I must play it!

rkolter wrote:And the thumb is hardly required - I have a friend who through the luck of the draw was born with three fingers, not five, and in an odd configuration - he doesn't have a thumb per say on that hand, and he manages to write, grasp, and throw frisbees just fine with that configuration. There are plenty of configurations that don't require thumbs.

I think the key word here is "opposable", not "thumb".
Heck, octopi seem pretty capable of grasping things, and they don't even have bones.


As far as if alien species would evolve to be humanoid, I would imagine the environment would play a major role in whether or not this would be true. (Well, obviously, but bear with me here...) I vaguely remember something from a science class that the reason certain animals (humans in particular) have evolved to be able to see 'visible' light is that our atmosphere allows that narrow spectrum of electromagnetic radiation to pass through.

I know that's not entirely true, but I did say "vaguely".

YarpsDat wrote: Giving it quick read, it turns out water and silicone life most likely doesn't mix. They'd most likely live in sulphur acid.

Or alchohol! *hic* Imagine that!

They'd get drunk on water.

Atomic Rockets: Aliens.

If you're going to be fiddling around with non-human intelligences and/or extraterrestial lifeforms, the above link provides a good primer.

EDIT: Relevant quote from the linked page

In classic science fiction, the buzz-word was "Silicon-based Life". Life on Terra is based on Carbon, since carbon can join with not one, not two, not even three, but a whopping four other atoms. This allows the construction of complex molecules like proteins and DNA, a requirement for living creatures. The only other element that can do this is Silicon, so the SF writers seized it. They are also fond of harping on the fact that while most carbon-based animals on Terra exhale gaseous carbon dioxide, a poor silicon-based critter would breath out silicon dioxide, i.e.,sand. In "A Martian Odyssey" by Stanley Weinbaum is a silicon life creature that "exhales" bricks of silicon dioxide, which it uses to build a pyramid around itself.

rkolter wrote:It must take in energy in some manner. For anything quick minded and quick of limb, it will probably be eating. Unless you encounter it in a vey hot (VERY hot - not habitable for humans hot) type world and give it some means of converting heat into other energy (maybe a natural steam engine!)

This would go against the law of thermodynamics, wouldn't it? What you need to generate useful energy is a temperature differential, not simply a high ambient temperature.

rkolter wrote:It may or may not excrete. We humans do because we are wasteful and poorly designed.

I'd disagree with this as well. If an organism were to live without excretion, then the by-products of its every metabolic process would need to be useful compounds. These compounds would then be used in other metabolic processes, resulting in more useful compounds, unto infinity. Also, such an organism would be constantly taking in mass, but would never lose it (except perhaps through reproduction).

I don't see excretion as a wasteful system, myself. In a perfectly controlled world maybe it could be eliminated. In a world where different organisms are evolving in competition with one another I don't think an excretion-free organism would stand a chance.