For those who are unfamiliar with Godwin's 1954 short story (which is included in a number of anthologies, including the book The World Turned Upside Down found here in the 'Best of Jim Baen's Universe CD), I'll include the Wikipedia summary:

The story takes place entirely aboard an Emergency Dispatch Ship (EDS) headed for the frontier planet Woden with a load of desperately needed medical supplies. The pilot, Barton, discovers a stowaway: an eighteen-year-old girl. By law, all EDS stowaways are to be jettisoned because EDS vessels carry no more fuel than is absolutely necessary to land safely at their destination. The girl, Marilyn, merely wants to see her brother, Gerry, and is not aware of the law. When boarding the EDS, Marilyn sees the "UNAUTHORIZED PERSONNEL KEEP OUT!" sign, but thinks she will simply have to pay a fine if she is caught. Barton explains that her presence dooms the mission and will result in the deaths of the colonists. After exhausting all other options (such as calling the mothership, The Stardust), he is forced to eject her into space.

I had one simple problem with the premise of this story, which kept bugging me the entire way through: With so many lives in the balance, why did they include so little margin for error? Things were measured almost literally to the last drop, with no room for any error.

Space is full of hazards, and there's no chance they have fully mapped the path between a random point in space and the destination planet. The EDS could face any number of minor navigation hazards on it's trip, which could require brief acceleration or braking to avoid. The planet's atmosphere may have local conditions which require more fuel (such as a storm which requires using more lateral thrust to land safely).

I realize the fuel is expensive and heavy, and they don't want to use more than absolutely needed for the job...but that's not what they give him: they give him the bare minimum amount of fuel needed IF NOTHING GOES WRONG. It's like they just want to taunt the demon Murphy as much as possible.

How could a society advanced enough to travel between stars be stupid enough to put people into such suicidally dangerous situations? Why didn't the pilot even investigate jettisoning mass equivalent to the girl's weight? Surely there is SOMETHING in the ship that could go.

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    I always had a bigger problem with the fact that, given a ship full of expensive pharmaceuticals, the only defense was a sign, not an armed guard... (Or maybe all the guards were defending the ship intended to just barely protect Earth from an alien attack).
    – John C
    Dec 11, 2011 at 14:35
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    This story was also done in an episode of the 1980s Twilight Zone reboot. Every time I see it, I think how absurd it is. It's done to prove a point that you can't mess with the laws of physics, but in going out of the way to make the laws of physics sentence her to death, the story ignores every law of common sense. (Besides, if she were on at liftoff, that would have used enough extra fuel right there to have endangered the mission if they really cut it that close!)
    – Tango
    Dec 11, 2011 at 22:00
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    @TangoOversway: You assume liftoff would be out of a gravity well. If they were ejected from a ship which had their correct starting course and velocity, they would use no fuel whatsoever until they had to alter course or speed.
    – Jeff
    Dec 12, 2011 at 6:19
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    @TangoOversway: It would, but that question is raised (and answered) in the initial story.
    – Jeff
    Dec 12, 2011 at 14:36
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    Most of the commenters expect the civilization to baby their citizens. The story doesn't expect that this will be possible. Armed guards? They don't have men to spare, and the pilot is armed to eject the stowaway.
    – Oldcat
    Mar 30, 2015 at 17:33

5 Answers 5


The Cold Equations was written as a heavy-handed morality play (for certain values of "morality"). Its purpose is to make a point, not to think things through. TVTropes has a 4-page-long discussion (Warning: TVTropes link!) about all the basic things the author screwed up on.

IMO the story is another example of the same mentality that led Asimov to come up with the Three Laws of Robotics. Sci-fi authors would dream up disasters that only occur because the "scientists" who invented the technologies in question and the "engineers" who built it did so in complete disregard of basic principles of science and engineering, and he felt it was an offense to human intelligence, so he decided to instead write about the sort of problems that could realistically occur even when the engineers and scientists got the basic idea right.


The story was intended to be used to illustrate the inflexibility of physical laws, possibly to encourage other writers of the time to pay more attention to their science.

In-universe, yours is a normal reaction to the scenario: Anything system designed with that little margin for error would be considered badly designed. The only possible way to rationalize this is to assume that this system developed due to a cultural blind spot and let it go at that. And the message (both in-universe and to the readers of the time) is that physical laws are absolute, and trying to get around them never ends well.)

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    A more effective choice might have been to focus on the life support; i.e., Air supply. It wouldn't take a lot to argue that a mild pad to allow for issues for one person was still woefully inadequate for two, and the pilot had to be alive to land or some such. Then again, I'm no author :)
    – K-H-W
    Jul 26, 2011 at 21:59
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    @Keith - The same argument, unfortunately, could be made about life support: What if the pilot had to orbit for a few hours before landing, in order to, say, fix a heat-shield or whatnot? There's not enough air for that? Well, that's sure some lousy engineering! Jul 26, 2011 at 23:53
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    Oh, no argument, but this type of fiction was often preoccupied with the absolute nature of natural laws and physics -- i.e., No amount of good wishes or what have you could change some things. As to doing it with an air supply, it would require a few more changes, but a simple way would be a 4 week trip, with 2 weeks extra air to allow for problems. That still wouldn't cover 2 people for 4 weeks despite a pad. Again, I think the author was less interested in the actual details and more in showing moral issue of Humanity and Human Concerns v.s. 'Cold-Hard-Reality of Physics.'
    – K-H-W
    Jul 27, 2011 at 15:57
  • @Neilfein scrubbing air can be a limiting factor. I think Keith's dilemma is more elegant. Life support doesn’t have to refer to total oxygen available, but how many life forms can be sustained.
    – user179700
    Jul 30, 2011 at 10:14

(The following is not an in-universe explanation.)

The Cold Equations was written (as the strong urging of John W. Campbell) as a response to a kind of story that was popular at the time, one in which human characters face seemingly insurmountable problems, but manage to find a way to solve them at the last moment.

I suspect that if Godwin had known that we'd still be talking about the story 57 years later, he (and Campbell) might have spent more effort setting up a more plausible scenario. Or maybe they wouldn't; Godwin presumably was writing for readers who bought the magazine that month, not for posterity.

The story is famous for its shocking plot, not for its technical accuracy. It would be interesting to read the (now forgotten) stories from the same issue of "Astounding" to see if their plausibility is any better.

There was a TV version of the story in 1996 which, as I recall, almost completely missed the point of the original story.

There's supposedly another version in production ("Currently In Production", "Coming in 2010", "Official Website Coming soon..."); we'll see whether and how that turns out. (Update as of 2017: HTTP Error 404. The requested resource is not found.)

I've seen one or two more recent stories that are responses to The Cold Equations, but they change the plot by coming up with a solution to the problem. It would be interesting to see a modernized version with the same plot, but with a more plausible technical background. For example, perhaps the lack of any margin for error could be the result of an unanticipated accident rather than something built into the design of the system.

  • The stories from that era that are still reprinted (i.e. the ones that I've read), rarely try for precise scientific accuracy, they just lay down the rules for this universe and go. Not a lot of room in the short story, after all. The "trying to stretch the time" subplot always bothered me because ballistics is one of the few subjects a lot of authors tried to be accurate on. Dec 11, 2011 at 16:59
  • And presumably the ones that are reprinted are of higher than average quality. Dec 12, 2011 at 8:23
  • More than two years later, the new production is still "Coming in 2010". Apr 3, 2014 at 18:52
  • And now it's a 404 error. Mar 30, 2015 at 14:20
  • +1 because I believe this level of dedication (updating a 6-year-old answer) deserves some recognition. It's also a decent response, in and of itself.
    – Jeff
    Feb 9, 2017 at 21:31

Despite the fact that many of the stories details are inaccurate, the premise behind the story and subsequent shows is accurate and correct. The laws of physics don't care one wit about human emotions and well-wishing.

With more careful thought, a story presenting this dilemma could be written with the same shocking ending and still be accurate.

As for the design being a poor design because the tolerances were too tight...

Space ships are not buildings or automobiles where margins of safety don't impact performance that much. The rocket equations dictate that rockets not have huge reserves of fuel and life support. This is not a matter of engineering and margins of safety, this is a matter of mass ratios. Depending upon the mission delta V required, an extra pound of payload might cost 4-5 pounds in fuel for each stage of the propulsion system. For a 3 stage rocket 1 extra pound of payload might turn into 216 lbs of propellant while a 150 lb teenager might turn into 32,400 lbs of propellant (the specifics depend upon the mass ratio required of each segment of the mission). The entire Apollo rocket stack used 7 different stages.

The rocket equation is a cold hearted bitch - thus The Cold Equations.

Consider: would the Apollo missions have succeeded if there was a 16 year-old stow-away on board? At the very least, Apollo 11 would have crashed on descent to the Moon. Similarly lunar landers were only able to lift a few hundred pounds of lunar material with it - about the mass of one human body without life support.

OTOH, as one of the previous answers mentioned, pods for such crucial missions would have used locked doors and/or guards to ensure there were no stow-aways. Also the stow-away should have been found after the initial use of the engines as the acceleration by the engines would have been too small.

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    This. Most criticisms about there being not enough safety margin around the fuel carried assumes a science fiction style universe like Star Wars or Star Trek where the energy density of the fuel used is so high that one can routinely travel with more than double the necessary fuel, in the real world we live in it doesn't work like that. Precisely because of the rocket equation. The more fuel you carry, the more fuel you need to carry to take-off and land safely. The story is actually valid criticism of handwavium power source in other sci-fi stories
    – slebetman
    Mar 30, 2015 at 5:32
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    Guards are a luxury when you need every man to do a real job. A locked door in an emergency is a danger to everyone. It is amusing how everyone here is ignoring the premise of the story - the fringe worlds and the ships who travel between them have no margin for error, and they expect adults to act responsibly, or take the consequences. As the girl did, when she understood what she had done.
    – Oldcat
    Mar 30, 2015 at 17:37
  • Yeah my last comment was based upon the late '90s short movie. In it, the ship was hauling colonists who appeared to have nothing to do. If you had colonists sitting around idle, then assigning some to guard duty of vital systems wouldn't be wrong. Now I need to go back and reread the short story. My recollection of The Cold Equations is swamped by that short movie.
    – Jim2B
    Mar 30, 2015 at 17:59
  • @Oldcat That's the whole point of my answer, though: We don't engineer things where there is no margin for error! Doing so would be absolutely stupid, because experience tells us that error is inevitable, so we create things to be able to tolerate error instead. The entire premise of the story is broken. If the only way to set up these colonies would be with no margin for error, we would most likely refrain from establishing the colonies until we could progress a bit further and be able to get it right. Feb 10, 2017 at 13:24
  • @slebetman - A perfect point. This is an urgent mission with the best available ship. The tank may be full to the brim and only just get him to his destination.
    – Valorum
    Jan 30, 2021 at 23:58

I think the other answers about the point of the story are probably valid - I do not know the story myself. However, there is no need to have the resources pared to the last drop to not permit another passenger. The resources - fuel, life support, food - that an additional passenger requires could be quite considerable ( especially fuel, if the trip is a long one ). It is normal to load planes with just about the right quantity of fuel for a trip, although not to the same precision. If the extra resources are significant, it could make all of the difference, without having the ship planned to run to the edge. If these sorts of trips are commonplace, then the resource requirements may be well calculated.

  • The mass ratio (mass wet / mass dry) is very different between aircraft and spacecraft. I ratio of 1.4 or so for aircraft is reasonable. While a rocket might need a mass ratio of 4. This has huge implications for differences in the design and operation of these vehicles. An aircraft factor of safety might be 1.5, meaning the aircraft is designed structurally to handle loads 1.5x it is expected to handle. Spacecraft factors must be much smaller than that.
    – Jim2B
    Apr 14, 2017 at 18:21

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