Inspired by How can civilizations develop if the day keeps repeating forever?

A similar experiment happens and a time loop is now created. The start and stop of the time loop is same for the entire universe.

Whenever the loop reaches its end

  • All matter and people are restored to its initial state. (except for the following exceptions)
  • People have full memory of the events that happened.
  • If they are awake, then they will know this has happened. If they are asleep, they will wake up immediately.
  • People who die will remain dead, but their dead bodies will go to their initial positions.

People do not age. There is hope (but no guarantee) that the time loop will repair itself exactly 100 years later. However, nobody believes they are capable of repairing it themselves.

How long should the loop be, for the world to keep developing without turning into a dystopia where majority of the population dies (either by murder or suicide, or really low birth rates)?

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    $\begingroup$ Regarding "low birth rates": how are newborns handled at the end of the loop iteration? $\endgroup$
    – user8808
    Dec 30, 2015 at 13:57
  • $\begingroup$ Excellent question, Roux. Assuming a 5 year cycle, if a baby is born two years into the cycle, that baby will cease to exist three years later. Can you imagine the trauma of that for parents? And the only way to get that baby back would be to exactly recreate the circumstances that caused the pregnancy, and even then, no guarantees. And think of the trauma for those five year olds who suddenly find themselves back in the womb. $\endgroup$ Dec 30, 2015 at 18:05
  • $\begingroup$ Would children be born or is that a function of ageing? Would the women just remain pregnant indefinitely? It's hard to say which is more traumatic in the long run. $\endgroup$
    – Separatrix
    Dec 30, 2015 at 22:06
  • $\begingroup$ @Roux People get unborn at the end of the loop. So birth rate is zero. $\endgroup$ Dec 31, 2015 at 11:31

2 Answers 2


Time loop questions have a nasty tendency to degenerate into messes. Usually you can sidestep a lot of the mess by having only one person remember what happened and then wave your hands emphatically to cover up the issues, but if everyone remembers, everyone's approach to the day is going to change drastically loop by loop. It, arguably, wont even be a loop anymore. It'd be more of a vortex. The effects of the radical application of dualism simply forces that sort of approach.

You made the rule that people who die stay dead. However, there was no corresponding process for creating life. Each loop, there would be fewer and fewer people, even if just due to freak accidents. If anything, this should be what causes the dystopia. The realization that the rules of the time loop are stacked so unbelievably and utterly against life itself, that everything becomes pointless.

So, if I may, I'd like to add a rule. You mention that people who die stay dead. However, what about the newborns who cross the boundary, do they get to stay alive? That would balance the life-and-death bit, giving the tiniest remote chance of anything except a dismal failure of society. But how can they live, if they don't have a body?

Oh yeah, there's a bunch of inanimate corpses at start of every time loop of people who died...

How about letting those who were not alive during the previous loop, but were given life during the loop inhabit the body of one who previously died (with some emphatic hand waving to deal with the case when the number of births is different from the number of deaths).

Now you have something that might be intriguing to live in: a reverse reincarnation world. Instead of an old self reincarnating in a newborn's body, you will have a newborn's self reincarnating in an older individual's body. The end result will be a zero sum physical universe, but most of the physical universe is already viewed as zero sum thanks to conservation of energy. We've had religions based on reincarnation before. I think you could last several hundred years with such a religion before the time loop repaired itself.


This is all set up in no particular order.

By the rules you've given, birth rate is 0 for the duration. I can see the parents of babies and young children going mad first (100 years and still changing the same baby's nappies because it never ages), followed by anyone whose project or skill takes longer than the loop. You'd need a system where everyone took turns to be caregivers to the aged who don't die and the very young who never grow up. Unless you want to just kill them all, corpse clean up will be an increasing job every cycle anyway.

Nobody is going to want to do the same thing day after day for 100 years.

Knowledge can develop, but practised skills are possibly reset on each loop. Everything built or consumed is reset on each loop.

Technology and industry have no requirement to be clean, resources become unlimited because you have the ultimate recycling system.

Criminal justice is going to be interesting. People should be released on subjective not objective time, but the records will all be reset each round and everyone will reset to prison/freedom as appropriate. People will have to be responsible for remembering who should be in or out. Is there crime other than murder or warmongering? Everything else is a temporary inconvenience.

I can see a tendency towards extreme socialism resetting all possessions to common ownership at the start of each cycle since nothing carries over. The other option is a drift towards "Mentats" where specially trained people act as the memory and banking system of a nation, allowing certain systems, including finance and property ownership, to continue "as normal".

I'd say 5 years.

It's the electoral cycle in this country so you could start each new cycle with an election. At the end of every cycle all the damage your government has done is reset and you get to pick a new one for the next round.

It allows the 10,000 hours required to perfect a skill. This means that you can start a new job at the start of each cycle, have time to get really good at it or really bored with it, then reset for the new cycle.

It's also enough time to develop friendships, have relationships etc. which will assist with the general mental wellbeing of the population.

It allows enough time to do a masters degree from a standing start. Education is one of the key things that will carry over, this will be key to the continued development of your civilisation.

You'll still get the steady mental breakdown of the increasing number of people who, every 5 years, wake up next to their dead partner and have to go through it all again. The longer the cycle the better.

I've only just thought of food. Given that the ageing rule would apply to plants and animals too, you're going to have to be really careful about animal/fish/plant stocks or you'll be on a diet of Soylent Green pretty quickly.

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    $\begingroup$ All good points. Although I will disagree with the point about babies. While their bodies will not age, their minds will. You will end up with a lot of dwarfish adults. Their bodies will be tiny but there's no reason they can't take care of themselves within the limits of their size. There may be some unavoidable physical limitations (undeveloped joints?) but most of a baby's helplessness is due to lack of experience. $\endgroup$ Dec 30, 2015 at 17:36
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    $\begingroup$ Saying that practiced skills are reset assumes that such skills are embedded in our flesh, not our memory, and that doesn't sound correct to me. From the point of view of the people, they are being moved back in time, but their essential selfness isn't being changed by that move. If you train intensively for five years at a martial art, I can't see any reason you would suddenly lose those skills from the reset. $\endgroup$ Dec 30, 2015 at 18:01
  • $\begingroup$ There's the question of muscle development as part of aging, there's also reach and dexterity. They may not actually be physically capable of taking care of themselves even if they have the conscious knowledge of how to, as per the very elderly. $\endgroup$
    – Separatrix
    Dec 30, 2015 at 18:02
  • $\begingroup$ As an example of practiced skills I'm going to use kick starting my bike. While I had the knowledge of how to do it, it took about a month for me to develop an extra muscle on the side of my calf after which I had much more stability in my foot to actually do it. Though the knowledge is not lost, muscles are. $\endgroup$
    – Separatrix
    Dec 30, 2015 at 18:05
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    $\begingroup$ Okay, that makes a lot of sense. If the job requires a particular physical ability (strength, flexibility, etc) that would be lost. In the case of the babies, you have to change their nappies because they don't know to hold it and ask for potty time. It would be a lot easier to take care of a baby with an adult mind. At least from a purely effort oriented point of view. Maybe worse psychologically, as they would probably tend to develop less than cute personalities. It would be hard to keep a good attitude, living life as a perpetual baby. $\endgroup$ Dec 30, 2015 at 19:23

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