Earlier today I was about a post a short story identification question asking about a short story involving survivors living among the frozen atmospheric gasses following a disaster where the Earth left the sun's orbit.

Thanks to the search feature, before making my post I discovered that the story in question was Fritz Leiber's A Pail of Air, which I just re-read at Project Gutenberg.

Is this story even remotely scientifically plausible? The ability of the family to maintain a breathable atmosphere, and to generate enough heat to avoid freezing to death, seems suspect. I'm willing to hand-wave giving them a large enough supply of food, and will grant them enough coal to keep the fire burning continuously. But even with those hand-waves, the set-up seems doubtful. And if it's not doubtful, why wouldn't other groups have survived the same way?

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    Questions about real-world science are off-topic. It would be on topic to ask for an in-world explanation. – Laurel Oct 27 '18 at 18:54
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    The guideline says "...unless related directly to a cited work of fiction." The question is directly related to a cited, and linked, work of fiction. Is there a different wording I could use that would resolve your issue with the question? – tbrookside Oct 28 '18 at 11:28
  • @tbrookside - The issue here is that you're not asking about whether it's plausible in-universe, you're asking if it's plausible in real life. – Valorum Oct 28 '18 at 22:26

No, it's not plausible. There are four main issues: Heat retention, thermodynamics, too much oxygen, too little water, air retention.

Heat retention is an issue. The basic problem is whether any plausible amount of coal burning will produce enough heat to replace the heat lost through leakage. I've worked with liquid nitrogen and liquid helium and the 200 degree centrigrade temperature difference between room temperature of LN2/solid N2 outside. I'm pretty sure that no plausible amount of casual insulation would retain enough heat for the kind of fire described in the story to keep the place warm. (Remember, it only takes a pail of air now and then to provide oxidizer.)

(If someone were so moved, they could easily calculate the heat produced by burning a pail of solid oxygen/hour and make an estimate of the size of the room and then compute the R-value of the walls needed to retain a livable temperature. I'm too lazy...)

I have further doubts about the thermodynamics of the burning. Assume that the insulation is perfect. There is still a lot of air lost through the flue, which carries away the combustion gasses but also carries away air. Can a bucket of air every few hours provide the oxidizer to burn coal and to replace the air that leaks out through the flue and the door? I strongly doubt it.

Speaking of air, as I recall they "mine" pure oxygen. A pure oxygen atmosphere will kill you if you live long enough after the coal and everything else flammable in the shelter catches fire. A pure oxygen atmosphere creates a deadly fire hazard -- as the Apollo 1 astronauts found out. And if any LN2 is formed, it can cause porous, flammable substances to detonate.

Water's another problem. They have a good source of oxygen and of carbon, but no source of hydrogen. If the shelter air contains any water vapor -- and it must for health -- that water vapor will escape with the flue gasses carrying away precious hydrogen. The shelter will pretty quickly desiccate.

Finally, the elephant in the room (in the shelter?) is air retention. Maintaining a breathable atmosphere against a vacuum requires good seals. The description of the seals they have is a guaranteed, continuous, substantial leak. (Which would substantially exacerbate the other problems!)

Bottom line: Not a chance. (But it's still a great story!)

  • Insulation isn't a problem. There's a vacuum outside. – JRE Oct 27 '18 at 22:56

Alas, although that was one of the first SF stories I read, I had problems with it as a kid, and have many more as an adult.

One overlooked issue is the strength of the building they live in. Let's assume that the internal air pressure is 15 psi. Then the load on the ceiling will be 144 x 15, or more than 2000 pounds per square foot. Granted, it seems likely than the internal pressure would be rather less than standard, at 1/2 atmosphere the loading will be more than 1000 pounds/square foot.

On one hand, standard construction rules address loadings of 10s of pounds per square foot, which is not even in the right ballpark.

On the other hand, standard weapons effects tables for nuclear blasts suggest that 5 psi will essentially dismantle a brick house.

Granted, the containment mechanism for escaping air was many thicknesses of blankets, rather than a solid wall, but this doesn't bear close examination either. If the blankets are not to flap, they must be tied to the floor and ceiling, and all of the load transferred through those fixtures. Besides, the central living area must produce full loads on ceiling and floor.

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