In a post-apoc world there are societies of people that live their entire lives in huge underground bunkers. They live there, as did their parents, as did their parents, and so forth.

Their only reference to time are the time-keeping devices they use that are based on pre-apoc time-keeping devices. There is no contact with the surface world or other societies.

If I wanted to steal time from these people, for whatever reason, say one whole day, I would likely go about stealing smaller units of time over a longer period of time. E.g. to steal a one day from a whole year I would:

  1. calculate how many minutes a whole day has: 24 hours times 60 minutes = 1440 minutes
  2. divide my minutes by a whole year of time-stealing: 1440 minutes divided by 365 days = ~4 minutes per day
  3. steal these for minutes over the time of a whole day: e.g. every 1 minute every 6 hours, or about 10 seconds every hour

Q: How much more time could I reasonably steal from my society? Or is this amount already too easy to detect?

  • People live their daily lives, they have good education and are a healthy mix of skeptics and non-questioning sheeple
  • Assume that I have full control over all time-keeping devices in this society.

Stealing time: A person has 24 hours every day, 365 of these buggers every year (give or take 1 very 4 years), and about 80-100 of these years depending on the person and their lifestyle (excluding manslaughter). If I, let's say, steal a day from them every other week, they lose about a month every year (give or take), that makes them lose a year every dozen of them, which makes them live only 74-90 years1 subjective.

1Again: give or take - this is very loose math, like doing algebra with spaghetti

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    $\begingroup$ What do you mean by 'stealing time', and for what purpose? $\endgroup$ Oct 20, 2017 at 13:59
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    $\begingroup$ @JeffZeitlin as in literally taking time away from them. As in the given example where a whole day of a year would be taken away without them knowing by making it as sneaky as possible. While I do not like to delve too deep into a story if I do not have to (general questions are also often provoking better answers, by preventing answers from fixating on a single story-related detail), possible applications might be 'artificially' reducing the life-span of people - thus supporting a mandatory higher birthrate; or just paying them one day of work less every year (or more...) $\endgroup$
    – dot_Sp0T
    Oct 20, 2017 at 14:05
  • $\begingroup$ Repost because I overread something: This is a wonderful question I believe, but maybe you should give more details. Do they use computers a lot? How do you change the time? Do you make time go faster in general or do you have it jump, let's say 1 minute only having 50 seconds? In that case it would be noticed rather easily even if just 1 second is slightly shorter, humans are good at noticing that sort of stuff - see music. $\endgroup$
    – Raditz_35
    Oct 20, 2017 at 14:10
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    $\begingroup$ What are the effects of stealing time? Also, does stealing time take it away from just one person, all people, or all things in the universe? $\endgroup$
    – HDE 226868
    Oct 20, 2017 at 14:10
  • $\begingroup$ @HDE226868 i thought the mentioning of isolated groups of people and the fixation on time-keeping rather than time as such in the body would help. I am talking about conning (only just found that word, hope it's right) people by pretending less time has passed than actually did. $\endgroup$
    – dot_Sp0T
    Oct 20, 2017 at 14:15

4 Answers 4


Quite a lot

Humans that have no outside time reference, being able to observe the day/night cycle tends to fall into another rhythm than the 24 hour cycle we are used to.

Now unless people still have their physics books and can make pendulums, and it is as you say that you control all time-pieces... then you can easily steal quite a lot of time. As stated on Wikipedia's page on Time Perception, you can safely fudge the time at least 1 second per minute. For older people you can do it up to 12-15 seconds per minute and they will not notice.

So let us say that if you are only gradually changing the clocks, you can safely move time-keeping up to plus/minus 5 seconds per 1 minute.

  • $\begingroup$ Let's take 5 seconds. So me as a hobby musician who usually plays this song at 120bpm will now have to play it at 130bpm? I think I'd notice that something is fishy - if this happens over night. If it's done slowly over thousands of years I wouldn't of course. Maybe I wouldn't expect that someone changed how time works, but if I lived in such a bunker and someone had reason to I might. $\endgroup$
    – Raditz_35
    Oct 20, 2017 at 14:14
  • $\begingroup$ @Raditz_35 "I think I'd notice that something is fishy - if this happens over night". Which is why I said — explicitly — "if you are only gradually changing the clocks". $\endgroup$
    – MichaelK
    Oct 20, 2017 at 14:16
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    $\begingroup$ @Raditz_35 Perhaps more interesting, the musician who plays at 120bpm would only notice the change if they were timing their piece w.r.t the "official" clock. Otherwise, they'd just play it at their natural pace, and the official clock would claim they played longer than they thought they did. However, once said musician pulls out a metronome (a clock that is not calibrated to the "official clock"), things might get dicey, because the errors would be readily apparent. $\endgroup$
    – Cort Ammon
    Oct 20, 2017 at 15:24
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    $\begingroup$ @Raditz_35 I suspect I would just assume I played the song at the wrong tempo and think 'Huh, that's weird. Could of sworn that was the right speed, oh well.' $\endgroup$ Oct 20, 2017 at 15:36
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    $\begingroup$ If you have no exterior reference frame? If you cannot see the sky, the sun the moon? Without an external reference to keep track of time we humans are really bad at it, $\endgroup$
    – Pliny
    Oct 26, 2017 at 16:47

Since you control all time keeping devices, it should be pretty easy to do undetectably.
Just change the length of a tick.
Each second only needs to be a micro fraction of a second shorter, which would be small enough that no one will notice.

You could probably reduce the length by a tenth with no one really paying much attention, except that cooking times might have to be adjusted slightly. This would make a pretty big difference though. You'd end up with 144 stolen minutes a day, meaning that people would get 2 hours less sleep a night, and lose 36 days a year. Each year would only be around 11 months long, so you'd turn 18 almost two years early.

Thanks Vault Tec!

Edit 2:
Due to some confusion on my part, I'm not sure if the Vault days are supposed to be longer or shorter than outside days... So I'll just double up to play it safe...

Lets say each "second" is 1.1 seconds long. that means that each day is 95,040 real world seconds, instead of 86,400 like on the outside of the vault. So each day would be 26.4 real hours long. Each year is 36.5 days longer in outside time. They would age much "faster". and be 20 when they finally turned "18". And yeah, they'd die younger on average.

But if you go the other way, and each "second" is .9 seconds long, then you'd end up with 77,760 real world seconds a "day". People would age slower. Each day would be 21.6 real hours long. Each year is 36.5 days shorter in outside time. People would age slower and live "longer". You'd be around 16 when you turned "18".

  • $\begingroup$ @dot_Sp0T 36 days a year. Every year. Forever. $\endgroup$ Oct 20, 2017 at 17:58
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    $\begingroup$ And for the cooking time change, you can just say that the cook books were written up on the surface where the air pressure is different. Down here in the bunkers, things cook a little faster because of the weight of all that stone above us. But how do you explain away the minute waltz that now only takes 54 seconds to play? $\endgroup$ Oct 20, 2017 at 18:05
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    $\begingroup$ @HenryTaylor "Minute, isn't that French for small? Something like that. Anyway, they called it that because it's so short." (It works because it's true.) $\endgroup$
    – AndyD273
    Oct 20, 2017 at 18:09
  • $\begingroup$ I think it would be difficult to change the sleeping pattern for the whole of society very much. If you over did it the average person’s internal clock would start to run adrift from clock time and the people would start to be half asleep during the day and waking up later and later. $\endgroup$
    – Slarty
    Oct 20, 2017 at 18:19
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    $\begingroup$ @Slarty In response to the asertion that "after 20 years, days and nights would be 3 hours long": I have no idea how you're arriving at that figure. You don't continuously increase the differential forever, you increase it to 10% and then leave it there. $\endgroup$ Oct 20, 2017 at 19:34

Some thoughts...

Can you engineer a power outage? If so, once power is restored you can fudge how long the lights (and clocks!) were out. Tell people that it sure felt like forever, but it was really just over an hour...

Another answer suggested fiddle with the clocks to steal a few seconds from every hour; this adds up pretty fast, when you consider you're stealing time from each member of the community!

Another opportunity for stealing time will be when people are ... distracted. Have community parties. During the party, snag a few seconds here and there. Heck, even an hour. People will eventually look at the clocks and say, "Wow is it midnight already?" You can just smile and say "Time flies when you're having fun."

If you really want to kick your time-vampire shtick into high gear, go to the old folks' warren. Find the old guy snoozing in the armchair and take hours from him.

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    $\begingroup$ "What are these monkey electricians doing? We are having so many outages recently, almost every month..." all the while you steal their time $\endgroup$
    – Ángel
    Sep 13, 2020 at 0:39

You may control the clocks, but do you control everything else? If, for example, your people are so far gone they can't remember "One-Mississippi" (or some such) to vaguely guess the length of a second, etc., then there's no point to your question. Therefore, you need to "steal the time" in such a way that their fundamental sense of time is not compromised.

Here are some limitations to what you can do to "steal time."

You can only take the time while they are sleeping.

People have an innate sense of time. We're basically diurnal in nature. We can consciously detect when things happen too quickly, like a pot taking no time at all to boil or the "sleep period" happening even an hour ealier than just a couple of weeks ago. After all, eveybody's tossing and turning and not falling asleep. But, shorten the sleep cycle... humans can live on short sleep rather effectively. Especially if it's treated or society changes to accomodate the challenges created by too little sleep. And it's something that can be accomplished gradually without notice.

Your society must never have a reason to doubt their clocks.

There are many ways to test time without the sun. Water clocks have been used since time immemorial and are fairly accurate. For checking just one minute, "one mississippi" is tedious, but reasonably accurate. The lower the tech of the clock, the harder it is for you to justify some villian's control over it in your story. Worst of all, the CD jacket says the song they just listened to is 3:53 minutes long but the clock says 4:00 minutes passed (hmmmm....). Therefore, one minute must always be one minute when they're conscious.

If your goal is to eventually remove them from the bunker, then your theft must synchronize with the outside world.

In other words, if they open the doors at 9:00am outside, the clocks had better say 9:00am inside. I'm making an assumption based on facts not in evidence as you haven't explained what's going on. If they never leave the bunkers, ever, then ignore this point.

But there is a deal killer....

There are a whoping number of things that are outside your control, like the lifespan of insects, the decay of radioluminescence, the frequency of a tuning fork, and most importantly, the harvest time of fruit and vegitables. You don't tell us how they're getting their food, but if they're growing it themselves, then at most you can take a couple of days per harvest or the gardeners will know the jig is up. Your bunkers and bunkettes have the divine gift of asking "what time is it?" and can therefore be manipulated, but the rest of the universe doesn't... and can't....


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