What Silicon-Based Life Might Be Like

Nancy_A writes "While the world as we know it runs on carbon, science fiction's long flirtation with silicon-based life has spawned a familiar catchphrase: 'It's life, but not as we know it.' Although non-carbon based life is a very long shot, this Q&A with one of the U.S.'s top astrochemists — Max Bernstein, the Research Lead of the Science Mission Directorate at NASA headquarters in Washington,D.C. — discusses what silicon life might be like."

Comments

Re:Easy

[Snard]

For those who don't get the reference: http://en.wikipedia.org/wiki/Horta_(Star_Trek)

Why not here?

[vlm]

Why not evolve Si life here?

Dorminey — WHERE ARE THE LARGEST CONCENTRATIONS OF SILICON HERE?
IN SAND?

Bernstein — In sand or rock. There are literally megatons of silicate minerals on Earth.

Talk to a geologist like my ex roommate. I knew there was something fishy about that so I checked the actual numbers:

http://en.wikipedia.org/wiki/Abundance_of_elements_in_Earth's_crust

Silicon 277200 ppm second only to oxygen
Carbon 300 ppm second to pretty much everything but vanadium and stuff like that. By weight the earth has about as much Rb as C.

For all intents and purposes the earth is not the idea place for a carbon based life form. Its the equivalent of a unit train full of high fructose corn syrup tank cars for a silicon lifeform. If they can't form here and absolutely gorge themselves on what to them would be the equivalent of a giant pizza, there is not a more ideal place out there to form...

The reason why we're made out of relatively rare C instead of tremendously available Si is C chemistry is incredibly better than Si chemistry for bio, or heck, chemistry in general. The fine article didn't give it enough justice or maybe the editors edited out the chemistry rants. Lets just say that Xe biochem is not all that more unlikely or difficult than Si biochem would be (in other words, nearly totally freaking almost incomprehendibly impossible vs just merely incredibly extremely impossibly unlikely)

It all has an air of speculative fantasy fiction, like trying to intellectually debate if its easier to make vampires, werewolves, or zombies...

Re:Why not here?

[meglon]

Better yet, talk to an organic chemist. First day of organic our prof detailed why silicon based life is a non-starter. Make chains of carbon and you get such an incredible variety of things that they make up over half the compounds known; make chains of silicon and you get: more sand.

Re:Why not here?

[sFurbo]

No, you don't get sand. The silicon equivalent of organic compounds are polysilanes, not polysiloxanes. Making them seems to have been a rather popular niche in the 70's. However, they are unstable, as Si can form more then 4 bonds, so isomerisation is much more rapid than with carbon.

The reason 90 % of the known compounds are organic is because a) there is amble supply different carbon-based compounds to manipulate, as life has made sure, and b) they are more interesting as pharmaceuticals then inorganics. Based on pure chemistry, boron is nearly as versatile as carbon, but starting blocks for boron chemistry is harder to come by, as is funding.

Re:Why not here?

[polymeris]

where you get silicon & oxygen in sufficient quantities

Everywhere on the earth's crust?

I don't actually understand enough about the chemistry of Si & C to make a direct comparison, but regarding the issue of bonding strength you mention, wouldn't other factors, like temperature and pressure affect this? Possibly even making Si-based life fitter for some environments?

Re:There was a pretty insightful comment

[Rei]

The problem is of people envisioning silicon-based life in a manner that's too similar to carbon-based life. Silicon life, if ever found, is essentially guaranteed to not have any long Si-Si-Si-.... chains; they're not stable. The silicon equivalent in terms of stability is Si-O-Si-O-Si-O... etc (silicone). Silicon also has some fascinating complex chemistry in the form of silanols, which can form membranes, catalysts, and all sorts of other fascinating stuff... so long as they don't get too hot or in too acidic or basic of a chemical environment.