Silicon vs. Carbon: Why is Silicon-Based Life So Unlikely?

[DaveC426913]

This forum

http://www.bautforum.com/

is a little more lenient on wild speculation.

 

[Chaos' lil bro Order]

Please let me know if my queries are inappropriate for this forum, and if so, any alternative forum suggestions would be greatly appreciated.

I realize I'm pushing an unnatural idea, but it's for a story I'm writing. So, without getting into too much detail at this point, let's use those magical words, "What if..."

What If: a man from a parallel dimension, who eats silicones (gels, etc.) crosses over to our dimension?
- What could he eat here, in our dimension, off the shelf? (hair-care products, cosmedics, etc.)
- Are there different "grades" or "kinds" of silicones that he would be prone or adverse to?

What If: silicone gel is required for the trans-dimensional trip?
- could it behave as both an energy conductor and a buffer for the traveler?

Again, this is a fun, creative inquiry, not so much a science fact check.

Bill. Since you are writing fiction, you can just make up what you like. There are few rules of thumb in chemistry as to what is poisonous and what is not. If you want a rough guideline I can give you some tips as to what molecules tend to be detrimental to human health.

Dioxins (molecules built around two singly bonded oxygen atoms)

Most substances that contain halides like CL, BR, F, etc. (this is because these atoms have such a high electronegativity that they tend to break apart other normally stable biological molecules). Popular examples include Chloroform, Fluorides, Hydrogen Bromide, etc.

Alkaloids, which is a fancy name for bases, tend to be detrimental to humans since our body is acidic by nature and much perfers them. Of course there are many healthy foods that are alkaloid. But some popular toxic alkaloids include Ammonias, Indoles and amines (for amines, think of methamphetamines, morphines, heroin(es), etc.) All of these alkaloids mentioned are nitrogen-based, but they don't have to be.

Undigestables like celluloses found int tree-stuffs. The reason humans cannot digest things like wild grass and tree leaves is because they are primarily cellulose based. We lack the proper enzymes (keys) to open up and unlock the energy in these molecules, therefore they simply pass right through our digestive tracts. Cows and grazing animals on the other hand have the proper enzymes. Interestingly, cellulose is nearly identical to many sugars like glucose, except for a tiny area of the molecule where an -OH is affixed instead of an -H. Enzymes are very picky and just like keys, you know that one extra notch means the lock just ain't going to open!


I have tried my best to help you. In my opinion it is quite likely that a silicon-based 'human' would encounter the same or similar problems metabolizing such toxic molecules as we would. But as many people have pointed out this thread, its really impossible to know this so we can only make semi-educated guesses.

Hope you find this usefull. Chao.

 

[Roy Edmundson]

Lets look at the situation with carbon based life as we know it. There are complicated molecules for storing genetic information (DNA), mechanisms to translate this information into structural molecules, enzymes and hormones(proteins) and biochemical pathways to store produce and use chemical energy - carbohydrates and fats.
While silicon chemistry is similar to carbon there just isn't the same wide variety of compounds avaliable that would be able to do all these jobs. Large molecular weight silicon compounds exist, but are nowhere as structurally rich as DNA or protein. mostly they are just silicon and hydrogen without nitrogen phosphorous or oxygen. So its dificult to see how silicon life could store and use the necessary genetic information.
Carbon life is very compatible with water as a solvent . A solvent alows the movement by brownian motion of all the biochemical compounds within the living cell - a viable silicon lifeform would also need mobility, however water is out and there doesn't seem to be any other alternative solvent . Carbon life with water as a solvent is able to handle most simple carbon compounds without geting wrecked - ie poisoned. carbohydrate metabolism has pathways to utilise a great many of the small molecules containing carbon - eg acetate, malate succinate, ethanol, glycerol, acetone. there are relatively few poisons that life often encounters - most of us die of old age rather than being poisoned. Silicon life looks likely to have many more problems in this department - oxygen might be an unsurmountable problem because SiO2 is a solid. Water might be a poison as well.

I still believe in the possibility of silicon life, but I think that it might well be electronic rather than chemical.

 

[Jimmy Snyder]

But strangest of all... their telescope optics would be made of meat! (their version of meat, SiO2) Or perhaps dressed up corpses (coated optics).

Much as our diamonds and pencils are made of meat.

 

[DaveC426913]

Much as our diamonds and pencils are made of meat.

Good point!

 

[DTSchaefer]

Much as our diamonds and pencils are made of meat.

well, that's a good point, because the molecules that make up living organisms are far more complex than the crystalline carbon structures of diamond/graphite/nanotubes/etc. Who is to say that silicon-based life isn't made of the same large molecules?

So, same substance, different form, NOT MEAT. For both S and C based life.

 

[vaazu]

But if we would assume that the pressure and temperature wouldn´t be the same in the other environment. Then could Si compounds be more stable? And the oxidizer (i hope it´s like that in english) wouldn´t be O. For example F. Then SiF4 (it should be a gas) could play the role as CO2. Or is F so strong oxidizer that it would oxidize any Si compound, so the life could not stay? Or maybe the life could live in a liquid environment where the liquid is reductant, so the energy would be generated by reducting food. How unlikely is reducting atmosphere? Would H2 be it?

Hope anyone can catch my ideas :D and say anything about them.