Say you are 30 years old, and something happens and you wake up and find that you've been transported backwards in time to when you were a teenager [you were inadvertently sent back, you do not have control over the process or if it happens to you]. Physically, the whole world appears to be exactly as it was the first time you were a teenager: your surroundings are identical and your outward appearance is identical to how it was. However, your brain is different in the sense that you have your 30 year old pre-transportation brain: you remember everything from your life that happened up to when you were 30 and were transported back in time.

From talking with people around you, it seems like they did not have a similar experience, i.e. they were not transported backwards, so they do not realize that a jumpback event occurred. However, you cannot assume this is true of everyone, i.e. it is possible that some other people were also jumped back. In fact, you should assume that at least some other people also were sent back, you just don't know how many or who they are.

  1. What are some very concrete steps you need to take to conceal the fact that you were jumped back? This involves 2 parts: hiding the fact from other unsuspecting people, and hiding the fact from other people who also jumped back.

  2. How could you identify other people who jumped back without revealing that you were jumped back?

**It's true that if you had technology to see the structures of a person's brain, you could determine that a given brain is unlikely to belong to a person of a given age, and use this to classify people as jumpers/non-jumpers. But I'm mostly interested in other methods besides physical brain structure. E.g. taking advantage of assumptions that a jumper might have based on world events they experienced, such as "accidentally" knowing who Obama is even though the year is only 2002, or "accidentally" knowing that some sports team won X championships when in the present year they've only won X-2 championships, or Googling movie or song or book names before they were published, etc.

***Also, how does this change if we don't assume that the jump increment is the same for all jumpers? E.g. you may have been jumped back by 15 years, but another person may have been sent back 5 years, or 50 years.

  • $\begingroup$ Whether the jump increment is the same or not, is everyone's "target past" date the same? That is, did everyone go from [whatever date in future] to July 3rd, 2002? Or is their "target past" date different? $\endgroup$
    – Azuaron
    Aug 31, 2016 at 17:29
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    $\begingroup$ Hiding that you jumped back would be extremely difficult. Unless you can somehow plausibly explain your very specific partial amnesia you'd surprise a lot of people with scenarios like the following: "Hey Bob, what do you think about the movie we saw yesterday?" "Umm... do I know you?". You simply forgot too many things which are integral to your past life. There's also a very big change in personality which you can't hide since you don't know how past-you behaved. $\endgroup$
    – Annonymus
    Aug 31, 2016 at 17:37
  • $\begingroup$ In general there is no shared increment or target past date. However, I am also interested in how the analysis might be different under that condition. So let's just be sure to say which "target past date" assumption we're using in any discussion. $\endgroup$ Aug 31, 2016 at 17:39
  • $\begingroup$ Not sure if it would work but to find other jumpers you could try posting on social media (if it exists) things like 'Thinking of heading to the Twin Towers tomorrow' on the 10th of September and see who responds with attempts to convince you not to. $\endgroup$ Aug 31, 2016 at 18:16
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    $\begingroup$ You might want to check out "The First Fifteen Lives of Harry August" by Claire North. It explores some interesting implications of 'looping' into your past life. $\endgroup$
    – Dan Bryant
    Aug 31, 2016 at 18:44

6 Answers 6


If it is your past, you won't have any trouble. You will adapt well. But depending on your social status this could be an immensely traumatic experience. Imagine loosing your child, knowing that you will never see him/her again.

To find others, or rather for others to find me, I would sing songs from the future in a convention of some sorts; making sure that a lot of people would listen to it. For most, I would be a one shot wonder, but those few who had experienced the alternate future, they would know about me.

Also, you going back in time may change the outcome of everything, including teams winning/loosing matches or presidents not getting the office. Things that are quite certain would happen the same way. But others triumphed by a few percent may go the other way. I will call this bubble of change. As you are changed, everything around you will be affected, and in time this bubble will grow and eventually, time streams would be quite different after sometime.

Edit: A similar concept was used in http://www.kongregate.com/games/StuStutheBloo/no-one-has-to-die

  • $\begingroup$ I though we were meant to avoid being found. $\endgroup$ Aug 31, 2016 at 18:49
  • $\begingroup$ Ordinary people will never find it, only time travelers will know a song from the future. $\endgroup$ Aug 31, 2016 at 21:50
  • $\begingroup$ Question asks to hide you are from the future ALSO from time-jumpers. $\endgroup$
    – Masclins
    Sep 1, 2016 at 11:01
  • $\begingroup$ Oh then that part won't work. Hiding is quite easy so if they don't want to be found, you wont be able to find them $\endgroup$ Sep 1, 2016 at 17:42

Hiding Won't be hard, true you would have some memory problems at first but most people would just think your confused and would not jump to the conclusion that your a time traveler. As time went by surround by your teenage life your brain would start bring bake to you all the memories you had for gotten.

Not sure how to find other like you other then to watch out for people look confused or can't remember yesterday or start showing new skill that should take several year at least to learn


I think you'll have a difficult time hiding that something happened, though non-jumpers are unlikely to guess the details of it. For one thing, if your parents are alive when you're a teenager, they are almost certainly going to notice the sudden shift in demeanor and behavior. The mindset of a 30-year-old is vastly different from that of a teenager (well, for most people anyway...) so the rather sudden shift is going to be jarring for everyone who knows you. If I saw this in my child, I'd probably guess something deeply traumatic must have happened to cause such a dramatic change.

If you want to try to identify other jumpers without revealing your own nature, one option (as others have mentioned) is to look for signs of unusual prescience in folks who are less careful about hiding. The tricky thing about timelines, though, is that actions may well change them. Even worse, if your world has a multiverse structure, the different jumpers might not even come from the same facets of the multiverse, having jumped back from different branches of possible realities.

In that latter case, what you're left with is looking for signs of people who had dramatic shifts in behavior/personality, perhaps at around the same age as you (working on the premise that it might be age-specific.) For instance, this might result in trips to see a therapist instigated by worried parents. Or maybe find stories of people who were doing poorly in school, then suddenly became excellent students. Or possibly look for stories of awkward nerdy kids who rapidly showed a huge jump in confidence and poise. Perhaps even look for stories of prom queens who abandon their cliques overnight in favor of different pursuits. These kinds of things will be easier to spot if they happen at your own school, but some shifts might be sufficiently dramatic to result in news articles in local papers.


In the novel I recall, he (and the person he already found) posted a newpaper ad with the “remember when” theme, listing slogans from the future. A few replied with wrong ideas about what the ad was concerning. One replied with proof of his own, adding Tylonol Scare and Princess Di to the list.

Posting such an ad would be a good idea. Though it could be better couched as a legitimate ad for something. It gets people who share your memories to notice that fact, while being unsuspicious to the masses.

It also helped that they knew which stocks to buy for long-term investment, simply from remembering brand names in the future. Investment consultants were the cover they used when visiting the other guy they had found (who was in an institution for the criminally insane, BTW).

Oh, he found the first person (his companion in the rest of the novel) from a movie she had made. It was a huge blockbuster, and he remembers themes from movies that were later in time in his original future. In the credits he notices famous (to him) people who were as yet unknown at this time, indicating that the filmmaker somehow was able to pick them out before they became famous.


I would conceal myself (and temporal point of origin) by engaging self-hypnosis techniques to more fully recall exact mannerisms, expressions and current events, and implant inhibitions that made it difficult or impossible to discuss things that would give away your status, i.e., no reference to things like Blu-ray, flat-screens almost all references to todays pervasive technology like smart phones. I would also watch for others by looking for 'unknown' buyers and investors in dot-com bubble stocks or futures, people cashing in on the ultimate insider information. Once located, I'd approach them with caution, but using specifics in small talk, like " I'm gonna make Mexico pay for it - it's gonna be 'Yuge'" find what they know, and find out if if there is a way home again... Just my opinion


Are you wanting to look for any jumpers, or in particular for any of your companions who may have jumped back along with you?

For close companions whom you met in later years, you may know or have been told their parents' address (and they similarly might know yours). You could write them a short note, with no return address, along the lines of 'Hi, it's Sam! I'm back staying with Mum and Dad again. Drop me a line if you want to get in touch.' Then if they have also jumped they will understand the message, (hopefully) remember your address, and will write back. If they haven't they won't understand it and will ignore it.

For people you already knew as a teenager, it will be pretty easy to look at their behaviour and see whether it has changed – and in particular if any memorable event involving them goes a different way.

I'm wondering why you want to conceal your jump. Is it simply that you don't think anyone will believe you and you want to blend in, or are people aware of jumpers and prejudiced against them? It will be much easier to hide your true nature under the first circumstance than the second.

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    $\begingroup$ In the novel I recall, the time they came "out" they got snatched up by the government. They most definitly wanted to keep secret. $\endgroup$
    – JDługosz
    Sep 1, 2016 at 10:24

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