Consider a fantasy species of "natural" time travelers. To define some specifics:

Relevant Rules

  • While it is not effortless, this species can move against the "arrow of time" much as a human can swim upstream a gently flowing river (and they don't need a machine to do so). The swimming metaphor continues: they can "speed up" (or "slow down") the process with effort, to a certain limit. They experience their own subjective time, and age accordingly.
  • We have limited multiverse theory: Changes made in the past "fork" into new timelines. These timelines do not exist until created. Not all possibilities actually exist. It is also possible to move laterally from (existing) timeline to (existing) timeline, with some concept of 4D distance between them. To extend the swimming metaphor, they can get out of the water and walk to another stream, which also takes subjective time and effort.
  • The species only has one point of real consciousness, or "existence"-- that is to say, they can't interact with their subjectively past selves. If they go back in time, their former double vanishes from the new fork. If they meet with a past version of a friend who is also a member of this species, that friend vanishes in the new fork. Of course, they can sync up if they like.
    • Non-members of the species still exist across the timelines at every point, and fork as needed.
    • Technically, it's not a single point, but a small "area" of time lasting a few moments, to allow things like seeing a friend moving backwards in time for a short duration before vanishing.
    • You can't really save a friend's life except within this tiny little window, because going outside the window will have the friend vanish from your perspective.

Other Rules

These are, in my mind, less relevant to my specific question, but since time travel is such a weird thing when you think about it, I may as well show you how I've hammered out other aspects for my story.

  • They can drag a fuzzified amount of matter along with them, such as clothing, held objects, air, etc. They also push on matter in a 4D way. This is like making little eddies in the water, and avoids XKCD "what If: Relatavistic Baseball" effects.
    • This doesn't make an infinite number of forked timelines as they go back moment by moment, but will build up effects that influence the new timeline once the person starts going with the flow again.
  • Changes to themselves persist. If shot with a gun, going back in time might see the bullet ejecting, but it's not going to heal them from the bullet wound.
  • Their location, and forces acting on them at that location, stay intact (unless they're stepping outside the timeline... but they need to step back into a timeline to go backwards instead of laterally). Jump off a cliff and start going back in time mid fall, and you're just going to keep falling as you go back in time. You can see other people and things reversing as you fall, but you keep falling. No "Prince of Persia: Sands of Time" here.


My question is: how could such a species have a meaningful society amongst themselves? Even with the restriction that timelines don't exist until created, it looks like they would have a problem of getting hopelessly separated from each other, eliminating any possibility of civilization. For that matter, it would make finding a mate nigh impossible, and since they aren't immortal that would mean the end of the species.

So how could this work?


4 Answers 4


Imagine this scenario: our group of friends decide to explore a complex and unending cave system. It's quite easy to get lost or separated, and not feasible to always stay in line-of-sight. How would we manage to stay connected?

We simply decide on a rendezvous point -- a safe base to return to after taking a jaunt through the caves. That way we can go off on adventures, but always come back to family.

At first, treks would be limited by our memory of the branches and our social needs. But over time, one rendezvous point would become many, spread out over the branches. we might develop technology like maps, compasses, and navigation apps to help us find our way. We might also make signal flares, radios, then texting and video chat to stay connected over longer distances. We might even invent cars and trains that move us through the branches with ease.

But some of our oldest cities would still survive. They were established with the limitations of older technology: centrally located among the branches, easily defensible from attack and not prone to disaster, yet near convenient outlets for transportation. Their wide but winding streets would follow the turns of the ancient branches they were founded on.

In short, your time travelers need a home.

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    $\begingroup$ I like this metaphor a lot! This makes sense. $\endgroup$ Feb 8, 2019 at 0:11

Society form when its potential members need to act collectively to improve their circumstances and survival. You have identified the biggest problem experienced by your natural time-travellers. Namely, that a time-traveller will cause their own past self to disappear. Since this also applies to other persons close to themselves. For example, their friends and so presumably close relatives too. This will tend to cause any grouping of these time-travellers to be dispersed across a plenitude of divergent timelines.

Therefore, natural time-travellers will form a society based on behaviour and procedures that will restrict time-travel itself. Basically this is intended to prevent themselves becoming separated across the timelines. This could mean that a tribe of natural time-travellers will keep together almost all of the time. When they travel in time they will all travel together. This will mean no single natural time-traveller can slip back into the past alone. The objective is to prevent losing themselves and becoming separated.

Societies tend to develop rules and laws that are to their advantage. For example, the time-travelling society postulated by this answer will be able to protect itself from large-scale harm because they will all travel against the arrow of time together and reach a point in the past where they can take action to evade whatever the harm was. For example, a volcano erupts and a tribe of time-travellers goes back into the past far enough before the volcano erupts to be able to leave the vicinity and go to where they will safe from the volcano.

It may seem paradoxical from a society of natural time-travellers based on restricting or regulating their use of natural ability for time-travel. However, if such societies can use their time-travel abilities on a community basis this will confer enormous social advantage. This will eb the basis for a meaningful society for natural time-travellers.

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    $\begingroup$ I was kinda hoping to write a story that would involve a little more individual time travelling, but what you say makes a lot of sense. Necessity might very well call for laws or norms against individual jaunts. Hm. I still want individualism... maybe the main characters would have to be criminals, hermits, or exceptions in some way? $\endgroup$ Feb 4, 2019 at 3:47
  • $\begingroup$ @RichardWinters Every society has its deviants. The Tragedy of the Commons is that is always someone who wants to put their self-interest ahead of everybody else. My answer was focused on how a society would form with natural time-travellers. There can be regulated individual trips too. Plenty of scope to ring the changes on this set-up. $\endgroup$
    – a4android
    Feb 4, 2019 at 6:08
  • $\begingroup$ Plenitude. Good word! $\endgroup$
    – Joe Bloggs
    Feb 4, 2019 at 14:53
  • $\begingroup$ This is the social equivalent of Niven's Law of Time Travel: "If the universe of discourse permits the possibility of time travel and of changing the past, then no time machine will be invented in that universe." That is, no stable timeline will exist unless no time machine happens to get invented to change it. $\endgroup$ Feb 5, 2019 at 19:18
  • $\begingroup$ @WhatRoughBeast An interesting thought. I tend to think of this situation as one where time travel & changing the past co-exist, but are well regulated. That is possible even in Niven's scenario. The real basis for Niven's law was Larry Niven believed time travel was pure fantasy, finding speculatively offensive, and wanted to legislate their hypothetical existence into non-existence. Niven's Law is an amusing idea. Somewhat outdated by modern thinking on time travel. $\endgroup$
    – a4android
    Feb 6, 2019 at 3:33

Give them the instinctive ability to recognize each other's prime instances and to detect them across time and timelines. That way, when the nature of your world naturally separates them, they have the option of exerting themselves to reunite.

They would have strong motivation to both separate and reunite regularly, as their natural time travel capability allows each of them to undo any life-ending mistakes which their friends commit. When after exerting one's ability to re-synch with a loved one, one finds the loved one is now a corpse, all they have to do is swim upstream in this fatal time stream to a point where their friend is alive, so that together they can find/create a less tragic alternative time stream.

Similarly, they would have strong motivation to separate into distinct time streams regularly, so that at least one of them survives any dangerous moments.

A culture of such travelers would be complex and multi-layered, with a variety of fascinating distinctions, which are not available to us other species, who are impaled on Time's Arrow. Their history would be free to tragedy, with almost all mistakes from the past nullified from the perspective of the current moment. Their history in fact might look a lot like a Charley Chaplin or Buster Keaton movie, full of near catastrophes which miraculously work out okay.

Unfortunately, any current day adventures which you create with these creatures will also suffer from a guaranteed happy ending. As they now exist, your creatures are more powerful than you, their author. There is nothing you can plot into their creation which they cannot simply undo with a little effort.

You need to think hard and build a scenario which negates their advantage, so that at least the illusion of risk exists. Something for your reader to bite into. That is going to be the great challenge to using these characters in your writing, but if you can overcome it in some subtle and unexpected way... it will be marvelous!

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    $\begingroup$ The trouble with this (and my fix to the "only happy endings" problem) is the "only one instance of you" thing. If your friend is killed, they stay dead everywhere, because if you try to go back in time to fix it, in the new fork you create, your friend doesn't exist there. If you travel laterally back to where your friend does exist... he's still dead. If your friend is not a member of this species and cannot naturally time travel, this does not apply, and you are indeed effectively a god to them. Unless they get lucky and kill you. Then you die. $\endgroup$ Feb 4, 2019 at 2:18

Give them the additional ability to merge timelines. If they can create a new split surely they can also splice a timeline together. This allows for them to reconnect and find other Travellers as well as introducing some new fun issues!

What happens if a Big Bad is defeated in one timeline but they accidentally merge with a timeline in which he is still alive? What happens to the inhabitants who know that a certain non-Traveller character died and merge with a timeline in which they are alive?

That gives some story leeway. It would also allow the Travellers to have a means to have a regularly scheduled meeting where they can merge timelines and reassert a "Main" timeline. Think of it like GitHub but for time travel!


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