The Carbon Atoms in Your Body Turn into Silicon Atoms -- What Happens Next?

Question

In The Laundry Novel series, basilisks and associated weapons and creatures turn their targets to stone by transmuting 10% of carbon to silicon. Ignoring the question of how, what effects would this actually have? It’s shown to generate massive amounts of heat, but I’m more interested in what kind of stone this would actually produce if used on a human. Note: it’s specifically carbon, not living things. Paint has been shown to ignite in the same way.

SCORPION STARE is a weapons system based on reverse engineering basilisks and medusae:
"In the case of SCORPION STARE, about ten percent of the carbon nuclei in the target are randomly transformed into silicon nuclei as if by magic. Messy pyrotechnics ensue: gamma radiation, short-lived muons, some really pretty high-energy chemistry, and lots of heat. We worked out how to do it by reverse-engineering basilisks and medusae—animals and unfortunate people suffering from a peculiar, and very rare, brain tumor. Now we’ve got defensive camera-emplacements on every high street, networked and ready to be controlled centrally when the balloon goes up. Street cleaning by CCTV-controlled flame thrower.

The technology itself relies on a trick of quantum observation that temporarily replaces the carbon atoms of the target with that of silicon. This causes an instantanieous chemical reaction, as carbon dioxide for example now becomes silicon dioxide, thus permanently altering the chemical make up of the entire object."

Answer 1

People Soup

Matthias says all the carbon is locked up in molecules in the person. This is correct.

Now turn each carbon atom into a silicon atom. The silicons can no longer form the same molecules. The molecules fall apart into loose atoms -- Is this where the heat comes from? -- and the connections between the molecules also fall apart. The person turns into person soup.

Why person soup and not person powder? It's because over half the human body is made of water. And water contains no carbon so is still water after the basilisk gets you.

For a normal person, the water is locked up inside cell walls and molecules, to the body appears solid. But turn the walls and molecules into powder and all the liquid is unleashed.

Much like the fruit smoothie above. The chunks of fruit look solid but somehow blend into a liquid when you chop them into tiny bits.

The person soup will be thicker than the fruit smoothie. More like mashed potato or banana or porridge. Or maybe refried beans. Yeah beans, that sounds good.

Answer 2

Short answer: There would be no apparent petrification, you would just see the human die.

Carbon in the human body is almost entirely part of organic molecules. So if the silicon just replaces the carbon it would not form any kind of mineral/stone but would just create organosilicon compounds (https://en.wikipedia.org/wiki/Organosilicon_compound#Silenes). Which look not like stone but more like this:

This is of course the pure form and regular organic molecules could just like this, when in their pure form. Pretty any process in the body would stop working more or less instantly, since the biochemistry of the organosilicon compounds is quite different. There would be no obvious change to an observer. So the affected person would just drop dead, maybe getting cooked by the heat.

There could be some rupture in the skin due to a lot of dead cells or the heat, but I don't know enough about this to make a prediction here.

Any non-living compound would just change chemical properties and would not serve its original purpose anymore. It could cause a decay, since the covalent bonds of silicon are weaker than with carbon.

Answer 3

The way to tackle this is to compare carbon and silicon chemically. They contain similar properties as they are both in the same group on the periodic table. Each contains four electrons in its outer shell, meaning it forms four bonds with other atoms. Theoretically, this would mean silicon could serve as a good analog for carbon. Practically, however, there are too many differences for this to be viable:

1) Size - silicon atoms have one more shell than carbon, making them much larger. If silicon would replace carbon in the body, there wouldn't be enough space for the atoms. Even if there was, the larger atomic size of silicon means it would mess with bond angles. The carbon-ring formation used throughout the body, including in DNA, likely could not form with silicon. So this could never work for steric reasons.

2) Polarity - silicon is more electropositive than carbon. Its extra shell means it has less attraction for electrons, and would therefore be more susceptible to attack by other compounds. Many silicon-based compounds are unstable and spontaneously hydrolyze or combust in water or air. So replacing silicon with carbon in the human body would theoretically result in a minefield.

3) Reactivity - silicon's properties make it most stable when bonded with oxygen instead of itself, unlike carbon, which frequently forms long carbon chains in the human body. Because of this, silicon would likely react with oxygen in the body, forming silica (SiO2) compounds. Interestingly, silica is a solid, found in quartz, sand, and other natural forms, which may explain the stone texture you describe.

More information on silica vs carbon chemistry could be found here. The article discusses the potential of silicon as a building block for life. This sentence is of note in our particular context:

Si chemistry in oxygen-rich environments (e.g., water) ultimately leads to silica (SiO2) (which is a refractory solid rather than a gas, with no double bonds to oxygen as in its carbon equivalent CO2)

This hopefully answers the question of what kind of stone would be produced by replacing carbon with silicon. However, it must be noted that this is not realistically feasible, due to the size and polarity constraints described. Moreover, as you mentioned, the process of replacing carbon with silicon generates an enormous amount of heat. This could be described as a reaction similar to nuclear fusion, in which two atomic nuclei collide forming a larger atom. This process releases a large amount of energy (think of the heat the sun releases as hydrogen is converted into helium). The human body could never sustain such an amount of energy, and therefore, even ignoring steric/polar constraints, a person would roast before silicon could react to form solid silica compounds (aka stone).

Answer 4

Burning death, meat spiced with amorphous silica remains

Let's look at the carbon in our bodies for a second.

The vast majority of carbons are linked to at least one hydrogen, and very many to two. Sugars, proteins, fats, you name it; they all have empirical formula CHxOy(Other)z, where H >= 1. Bear this in mind, it's important.

When you swap out carbon atoms like that for silicon atoms, you haven't made silicon carbide or silicones (those require there to be no Si-H bonds). No, you've made silane groups.

Silanes are highly flammable in air and react pretty violently with water under most circumstances. The slower, controlled reactions a few of you have encountered are exceptions deliberately engineered for that slowness. Silanes with the weird coordination environments you get in the body are not those exceptions, quite the opposite.

BURN!

You immediately cook. You don't explode, although a few small flames erupt on your skin. But the heat capacity of water wins the day here; you don't roast, you stew or maybe boil.

The product of silanes reacting either with aqueous species or air in small amounts is amorphous silica.

The remaining body is partially stewed and a bit gritty, being more than 90% cooked flesh and hot water and a few percent dispersed amorphous silica.

We hope that turning 10% of the brain's carbon into silicon immediately ends cognition before cooking commences, but who knows for sure?

PS Bump the fraction of transmuted carbon well up from 10% and consider swapping some or all of the Si for Ca or Al to get a mineralised body.

Answer 5

Atomics and other explosions

@Theresa Kay did a perfectly good job of describing the chemistry, but I've always wondered about the basilisk guns. You need to have one of two situations:

1. 10% of carbon gets an extra 8 protons, neutrons, and electrons, or
2. Pairs of C-12 fuse together to form Si-24

The second option is MUCH easier to deal with, as the person would explode. As you work your way up the periodic table, the amount of energy from each step up decreases, so you'll get less than 1/20th of the energy for equivalent hydrogen fusion. On the other hand, it's been calculated that a 50MT bomb only fuses about 2.33kg of hydrogen. If we're talking a 100kg human, then you're getting 1.85kg of carbon fusing into silicon. Let's call this something in the 1 megaton range.

However, let's say that such fusion energy was handled by the transformation magic. You'd still have the problem that Si-24 has a half-life of 140ms. Through beta decay, you'd wind up with a lot of magnesium, with traces of neon and sodium. Molecular cohesion would be non-existent, and the thermal effects of beta decay would boil the body instantly. Hot, bloody mist for everybody.

The first one would also result in an explosion, but the magnitude would be far less. A carbon atom is around .09nm in size, but a silicon atom is around .2nm across. The volume of carbon in a human body is roughly 1.1 liters. If turned to Silicon, that would add roughly 6 liters of volume, virtually instantaneously. I can't calculate how big the explosion would be because you can't compress silicon that much. I'm suspecting that we're talking about something that would take down a building.

@Andy273 brought up a horrifying third possibility, based on the wiki where the basilisk gun is described. This is where just the nuclei of the atoms are replaced, leaving an immense charge imbalance. It would be like lightning in reverse, only worse. Your typical lightning bolt has around ten coulombs of charge. The sudden increase in protons would result in a disparity around a hundred million coulombs.

Answer 6

Since the original question has already crossed the line by invoking a third party world, I'll invoke a Douglas Adams type of answer and go with 'bloodstone' to answer the question 'what kind of stone would it produce if used on a human?'

Though, of course, if we want to steer close to the science part of the science-fiction spectrum, we'd have to go with silicon carbide or carborundum.

Answer 7

Short answer:

You would die

Long answer: Due to carbon's mostly unique property of making bonds to itself, it allows long chain molecules that can store data (y'know, like our good ol' friend DNA) and gives living things energy as glucose. No Carbon, no energy, no information storage, no life.

You could also become a big, human-shaped, highly impure, silica mineral formation if the right combination was in your body