[World Building]Scientific Accuracy in Hard Science Fiction

[neodevilixir]

Hi guys,

I have a question to ask regarding World Building in (Hard) Science Fiction, and to what degree scientific accuracy is required for writers to write their novels.

Recently, I chanced upon this website on world building:
Worldbuilding Stack Exchange

In it, I read a few questions asked by other writers, in particular, the point about genetically modified humans being to breathe gases other than Oxygen.
Can a genetically modified human breathe something other than Earth's oxygen/nitrogen atmosphere?

This point is interesting, as the idea in my novel involves genetically modified humans that live in extrasolar planets in the distant future.
There are two kinds of humans in my novel:
1. Genetically modified humans with lungs that are able to filter out (most) toxic gases, and process oxygen from the atmosphere. They do not require to wear a pressurized suit in these planets.
2. Non-genetically modified humans, who require a breathing apparatus (gas mask) to breathe.

The question is, would my idea above be considered accurate for Hard Science Fiction?
Also, to what degree am I able to bend the accuracy to allow room for creativity?
(e.g. instead of lungs that process Oxygen, have the modified humans process other non-toxic gases like Nitrogen, since planets have high concentration of Nitrogen in their atmospheres)

 

[Onyx]

I don't think free nitrogen is at all common - nitrogen, like oxygen, is normally bound up in compounds like ammonia. And even if you have a nitrogen atmosphere, it isn't reactive enough to "fuel" life processes. It would be like substituting clay for nitroglycerin.

You could "filter" oxygen out of CO2, but that is really chemically cracking it which requires a large energy expenditure pretty much equal to the energy you're getting from the oxygen. But such a "scrubber" could be powered by some process external to the body. But that kind of energy could just be used to convert the body into rebreather.


So you are likely to need to stick to some explanation of how the people end up with oxygen in their blood. I could see adaptations that protect against free chlorine (filters, lipid membranes over eyes) or other toxins. I can't see modifying a human enough to have essentially a different cellular chemistry - like switching from carbon based to chlorine based life compounds - it would be easier to just make a person a closed system.

 

[Brian G Turner]

Welcome to the chronicles forums @neodevilixir .

As for your questions - some artistic licence is almost always inevitable, not least because there are bound to be advances in science and technology that we are not currently aware of.

In terms of breathing in gases on other worlds - that's only part of the problem. As mentioned in the StackExchange article, different mixes of gases are used in different environments, not least in response to higher pressures. So if you have people on other planets genetically engineered to breathe different gas mixtures, then you'll also probably have to have them adapted for different pressures and temperature ranges.

This all also presumes there are no biological materials that could otherwise present a threat.

However, the issue of breathing oxygen specifically is due to it being a core part of our biochemistry - other elements such as nitrogen are not going to be able to replace that simply because oxygen is highly reactive and nitrogen isn't. One possible replacement is sulpfur - this is used as an energy source for biochemical reactions by organisms evolved to survive by deep-sea vents - but this would require such a fundamental change in human biochemistry that I'm not sure genetic modification in itself would be enough, as much as developing a completely different organism.

As above, though, artistic licence is there to be used - it's more ideal if you really know your sciences to write Hard SF, though, simply because it would be easier to concoct even a brief solution to the satisfaction of the Hard SF readers will will necessarily judge the details in your story.

But remember as well that these are just details - they help complete the story, but aren't a substitute.

Anyway, hope that helps for starters.

 

[chrispenycate]

An oxidising atmosphere, with a lower partial pressure of oxygen and some impurities shouldn't be too difficult. They might look a little odd, increasing the airflow to extract enough molecules to concentrate, but biochemically they won't be all that different from their dome-enclosed companions.
A reducing atmosphere - say methane, carbon dioxide, ammonia and water vapour, as Earth's might well have been before the development of photosynthesis, is more difficult. Plenty of organisms around that would flourish in those conditions, but practically all are unicellular. And energy levels are much lower, metabolism slower - I'm not sure there would be enough for a functioning brain. And free oxygen would be a poison to them, as with all anaerobic lifeforms, so they'd have to wear suits indoors - very little mingling with their unadapted bretheren. The only ones who could socialise with both would be the space adapted, cyborgs who don't rely on external gasses at all, recharging themselves and using the energy to recyle all their metabolic wastes. Or we could go for photosynthetic algae under the skin so sunbathing could maintain blood sugar levels, and torpidity set in in the dark.

 

[Joshua Jones]

I agree with most everyone else here. An entirely new organism would be much easier to create than changing human biochemistry around that much. Now, you could fill their lungs with an engineered algae or something which metastasizes (insert relevant gas here) into oxygen, but that would require oxygen being in their biology somewhere. Or, preferably, in the atmosphere, and they are just cleaning up the other, poisonous chemicals from the air. And, if they harvested carbon as well, you could make respiration nearly irrelevant. At minimum, a person could go MUCH longer without taking a breath.

But, if you want to stick with your route, go for it. I stumbled upon this (Mohs Scale of Science Fiction Hardness - TV Tropes) last year, and it really helped me understand that one can write harder or softer SF and still have a market for it. My WiP is about a 4.5-4.75 on that scale.

I really like the possibilities in your idea, though! You will have to post a section in the critiques at some point!

 

[Onyx]

There's much to be said for not being specific:

"The Blah Blah's had an extra gland that filtered the atmospheric toxins out of their blood."

This is both in the realm of possibility but is not the subject of debate because it is not specific what toxin, how it is filtered or anything else.