Apologies beforehand for how long this is. The question is, with the time travel rules described here, how can I kill off the first time traveller?

I have thought of a system where the first person to discover time travel uses it to collect the various lost treasures (which is why we never find them) as start up capital. He then starts Time Investments LLC which sends people back in time collect some money, let it grow with compound interest, and collect it in the future. The economic issues of 2008 were caused by TI personnel removing too much currency from circulation, which caused the collapse of the delicate debt equity trades that J P Morgan and others were then blamed for.

If it is not obvious, the main character is low economic class, volunteering for this company to send him back. He takes the risk, they take 25% of his earnings from the endeavour.

EDIT Some more details that the comments reveal as important.

  • I am doing the single, flexible timeline. Yes, killing the first time traveller is going to make a lot of changes in this timeline, but the main character thinks it for the best and doesn't care what will snap back
  • At first my main character is volunteering for this just to make money, like everybody else. He then realises that this company's actions have already negatively impacted his own life, and wants to stop them.
  • The contract you sign with this company is to send you back in time for a consecutive period. You start a crowd funded project and let it fail, and deposit the money in their brokerage house, collect in the future. It would not make much sense for you to get to pick where you go, and they don't really give you a choice. They are only sending you instead of themselves because of the physical risk, but they want to control as much as possible.
  • Business logic is the main rule as to what can and cant be done in the company.

Segment of my narrative below.

Transportation was rough. The rumors on the streets had vastly differed on the details, but they all had that one right. Some thought that time travel would always be impossible and the claims of TI where just a cover for black market organ sales. There was plenty of that in the dark corners already, no need to start a large, shiny company to cover more. Another line of thought went If time travel was real, why hadn't someone gone back and fixed this mess of a world so that every one had decent food and a dry cot. The answer to that one was obvious now; because the people who had time travel didn't care about who's backs they were standing on.

Part of what they don't tell you before you agree is how it works. They give you something that looks like a pear sculpted out of a heat sink, its grooves filled with glitter. That is for your mouth, and that glitter holds enough oxygen to keep you alive for 3 hours (synthetic cobalt hemoglobin, University of Southern Denmark). You have to climb into a pod, morbidly shaped like a coffin, and calmly suck on your metal pear as the pod fills with electrolyk gel. Then you are electrocuted. To be fair, it is not electricity they pump you with but a different form of energy, the end result being an enormous jump in your potential energy measurement; but it feels the same. The pod holds some piece of you in your time, a bio signature, so that nature knows where to put you when it realizes that you are out of place. That usually happens in about two weeks, as your synthetic potential dissipates. So if you sign for a 3 month contract you just volunteered for 6 electrocutions give or take your personal resilience.
Time travel is like throwing yourself up a cliff, it takes a lot of energy and is against the normal way of things. Also, the top of the cliff where you now find yourself is shrinking, eventually becoming too small for you to stay and you fall off again. The physical sensations for the return traveler are peculiar, but not painful. The world around you starts to lose color around the 10th day. This decrease of detail escalates through your senses until a threshold is hit and you are suddenly sucked back. The 13th day is very dull, the sense of taste is gone, and the 14th-ish is down right depressing. Some people have an unusual resistance to nature; they are often the ones offered Warden positions because they require fewer shocks to stay in the past. Witnessing another traveler reach their threshold is still interesting. The spectacle is halfway between a pop and a zipper closing. The person flies to shiny pieces but at the same time all the space they occupy is being wrinkled and folded in; seamed up.

Part of what they do tell you are the rules that they have found do not bend. Most found by unfortunate circumstance.

One: You cannot jump to the same time slice twice. Your second entry breaks the connection of your first, and both copies of you are immediately returned to the present, with a very messy conclusion. This was confirmed with fruit, since one test is never enough for the scientists but none of them volunteered for the second. Related, you cannot jump to your own time because it causes a confusion of the bio signatures. Also tested with fruit. They have, however, shaved the delay for reentry to 6 minutes from your disappearance.

Two: Only organic material goes through, hence the fruit tests. One titanium joint was left inside the pod with the bio signature after the disapearance of the traveler. That is a horror story the street rumors actually had right, of a man trapped in a remote test location for a week, missing a piece of his internal structure. I will let your nightmares fill that one in, like mine have.

Three: An anchor point is needed, hence the use of the pods. If your bio signature is lost, so are you. This one still has some unanswered questions, because the return exit looks the same (pop-zip) but the traveler does not actually return.

Four: You Can cause chains of bad things, but they are always bad, and dont. Just dont. Part of the Time Warden's job is to identify who does what bad thing, and then a message is forwarded and they unplug your pod. It is in the contract; your bio signature gets purged if you step out of line. Things that are bad for the company are deemed more important than things that are bad for the world. After all, this is a financial institution, and we are here to make money.

  • $\begingroup$ What is our goal here? Is it to make the original time traveller be dead, or is the idea to travel back in time and prevent the original time traveller from doing something we already know he has done? $\endgroup$
    – Taemyr
    Commented Aug 28, 2015 at 7:33
  • $\begingroup$ From what I understand of your time travel ruleset, there does not seem to be anything that would prevent the main character from travelling to the same time slice as the first traveller, unless he IS the first traveller. Unless of course the corporate powers that be mark those time slices where the founder had gone as off-limits in the interests of temporal consistency. On another note, if you can cause chains of bad things to happen, it may not be impossible to harm the first traveller by setting up a trap at some time before one of his sojourns. Of course, paradox may still apply. $\endgroup$
    – LiveMynd
    Commented Aug 28, 2015 at 8:45
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    $\begingroup$ I believe it is "Compounded Interest" by Mack Reynolds. $\endgroup$
    – Oldcat
    Commented Aug 28, 2015 at 22:57
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    $\begingroup$ Since you get to decide your time travel rules as you see fit, I recommend gathering existing solutions from movies. The movies Primer and Twelve Monkeys are both excellent examples of time travelers dealing with the desire to change timelines. Robert Heinlein also has a vast series of time travel books with a completely different ruleset and very different results. (He also wrote "All You Zombies," which was a particularly mindbreaking short story about strange loops in time) $\endgroup$
    – Cort Ammon
    Commented Sep 24, 2015 at 5:50
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    $\begingroup$ As a note about organic/inorganic - this means that you arrive in the past missing all your fillings. Just another cost of doing business, I presume. Plus, what are you going to do for money when you appear in the past? How about ID? $\endgroup$ Commented Jan 19, 2016 at 21:22

3 Answers 3


For time travel to work, there cannot be any paradoxes. This results in exactly three options:

  1. Fate: the timeline is absolutely fixed. Everything a time traveler experiences in his life cannot change. This is a "no choice" timeline; everything is already fated to happen, so it will happen, regardless of what the traveler does. If the time traveler tries to kill his grandfather, he either ends up killing someone else, or simply fails to kill anyone. See All You Zombies.
  2. Alternate Universe: when going back in time, the traveler completely disconnects from his timeline. Changes made in the past affect the future timeline, but not him or his memories. He returns to the present by following the current timeline. Upon returning to his own time (if that's even possible), things may be radically different, including a duplicate of himself, or no version of himself at all. See Star Trek (2009) or Seven Days.
  3. Automatic Paradox Resolver: While a time traveler can actively change time, all paradoxes resolve themselves. Changing an event erases it from the timeline, which means that there was never a reason to go back and change it, which means the time traveler won't change it, which means the event happens, which means... etc. Only changes that do not create paradoxes are allowed to happen. Killing your grandfather is impossible; going back and investing money is possible. Saving your friend is possible if you make it look like your friend had died and hide him away until after you've gone back in time to save him, leaving your reason for going intact. Inside the universe, this seems identical to "Fate"; outside the universe, it's obvious that events are changing. The best way to fix things in the past is to make sure things happened the right way in the past; you never know if that bomb that didn't explode last year wasn't because a time traveler stopped it, so you send a time traveler to stop it. See 12 Monkeys.

So what does this have to do with your story? Well, if time travel is internally consistent and doesn't involve jumping between dimensions, there is no way to stop the original time traveler and erase the timeline he created, as doing so would create a paradox.

The only way to destroy the organization is to destroy it from the inside. One method would be to subvert what other time travelers are trying to accomplish, by breaking economies, stealing or pulling out funds early, and so on. Another method is to actually kill the original time traveler... then take his place. The organization will continue as before, until the moment the time traveler goes to the past, at which point the (older) time traveler will dismantle the organization.

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    $\begingroup$ #1 feels pointless to write. #2 means the money they shift is in another dimension, pointless. I like #3. They are going back and investing money, but before they go back they do not have the information needed to retrieve the money they squirreled away, so they don't know it is there, so they go back. The company running the thing does know the money is there, and knows who to pull off the street to make the money happen. The rules in #3 do not invalidate the pieces of the story I have sofar. I guess my hero will have to "change the past" to make sure the present happens the right way. $\endgroup$ Commented Jan 19, 2016 at 19:27
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    $\begingroup$ @DeveloperWeeks Type 1 Time Travel can be interesting to write about, but is very situational. The time travel Anne McCaffery used in her Pern series was Type 1. $\endgroup$ Commented Jan 19, 2016 at 19:47
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    $\begingroup$ While #1 may offer no choice for the character, the reader doesn't know how it will turn out, which is where the enjoyment comes from. In fact, I'd argue that for a writer, every story is like #1. Once written, the book is set in stone; no matter what order your reader reads the book, the ending doesn't change. That doesn't make the book any less (or more) exciting, though. $\endgroup$
    – ArmanX
    Commented Jan 19, 2016 at 19:58

Say there is a rival company to Time Investments, maybe from the future of your future (so our distant future) that wished to take out Time Investments by murdering time travels original discoverer but still leave themselves able to use time travel, therefore making themselves market leaders.

If the assassin is able to remember the process to create a time machine (a big ask but they are unable to take any notes with them, so it is the only way to do it), they will able to go back in time, kill the original inventor before they invent time travel, and then "invent" time travel for themselves or on behalf of their employer.

The timeline will otherwise follow roughly the same path, with the assassin filling in for the role of the original inventor, but with the new company in charge.

To tie this in to your story, as I do not believe your main character could be your assassin, maybe he is accidently transported forward by mistake, where he hears of the plan to murder the original inventor, slides back to their own time to discover the change has already taken place (Time Investments is replaced with the other evil corporation) and then takes it upon themselves to intervene in the assassination by transporting themself back to the time of the murder so you can witness what actually happened. In this manner, your main character could assume the position of the original inventor, or save their life and find themselves promoted (in gratitude) on their return to their time.

  • $\begingroup$ Adding a third party ... a good use of the naturally convoluted scenarios that come from a time travel trope. $\endgroup$ Commented Aug 17, 2016 at 19:17

The hollywood idea of time travel is that paradoxes don't exist simply because it is impossible to create a situation in which a paradox exists. If you went back in time to kill your own mother before your birth, something would go wrong, because being successful would create a paradox. This can even be fulfilled in strange ways which lead to interesting plotlines like, somehow you manage to kill your mother only to discover that she wasn't your biological mother as you thought.

The question to ask yourself is if this outcome happened to prevent a paradox or if you were never allowed to create a paradox in the first place. There is a difference. One is like trying to cut down a tree only to have the tree sprout new limbs supporting its weight and the other is already having those limbs in place despite not having seen them when you started.

So going back to kill the original time traveler would either fail because you were never going to succeed due to creating a paradox or you kill the time traveler only to find out he has an identical twin brother. If you double check his name prior, then he has an identical twin brother by the same name. If you check for whether or not he has family and has none and then you kill him, you will see a clone literally appear from nothing. It doesn't have to make sense, since you could think of time paradoxes a bit like dividing by zero.

A common solution to the time paradox is to assume that at the exact moment in time when time travel occurs, the universe splits. There exists the universe where you were never there and the universe that you just entered. In a sense, it wouldn't even be true time travel, more like interdimensional travel.

Therefore while you could go back in time and kill the original time traveler, it isn't a paradox, because you're not in your original universe, but rather in a copy of your universe at the point in which you jumped. Killing the original time traveler only lets the universe unfold as it would without his presence. When you jump back, you return to your copy of the universe that still had the time traveler.

However, this doesn't make for a very good story, because you're essentially saying that you cannot change the future by changing the past.

An alternative solution could be that yes, while you create a separate universe when you enter a new time period, you're merging your old universe with another upon your return. This means that somehow strangely enough, you have to still be able to be in the exact same situation that caused you to time travel in the first place in another universe.

In other words, you go back in time and kill the original time traveler. When you return, you enter the same pod you started in, however you find out that someone else invented time travel and things happened to go in a very similar fashion. Wait, it gets weirder. You weren't sent to kill that time traveler in the new universe. You were sent for an entirely separate task at the same time period (maybe kill the other guy who invented time travel that lead to that particular timeline). So many things can be different in the new universe, but it has to be a logical sequence of events that lead to you being sent to the same time and coming back. To those in the new timeline, it will be as if you accomplished nothing, however you've successfully managed to change the timeline of a universe that you are no longer a part of, since that would be a paradox.

Consequently, the people coming back from time travel missions are not the same people that went in, but rather they come from alternate dimensions.

It's just that this works out well when you don't set out to create a paradox. Putting money in a bank account to invest only to collect it in the future corresponds nicely with a universe very similar to that one in which the same thing happened, so you will have succeeded. However the protagonist might find that not everything is exactly as it was prior to starting the mission, but it is possible that not the protagonist nor scientists would be fully aware of the fact that time travelers are really just jumping universes.

This means that paradox missions would create very weird outcomes for those traveling, but also that paradoxes are not possible. I hope I'm clear. It is a bit difficult to wrap one's head around, I'll admit.

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    $\begingroup$ "The hollywood idea of time travel is that paradoxes don't exist simply because it is impossible to create a situation in which a paradox exists. " This is not the hollywood idea of time travel. The hollywood idea of time travel is that paradoxes only occur when it suits the narrative, and in all other cases it's something we can disregard. The formulation you state is possibly a mathematical fact. See authors.library.caltech.edu/6469 $\endgroup$
    – Taemyr
    Commented Aug 28, 2015 at 12:02
  • $\begingroup$ I was trying to hide character details, but your answer is missing some important things because I held them back. Part of the premise for my plot is a version of the grandfather paradox exists in this world, so I am doing the single, flexible timeline. Yes, killing the first time traveler is going to make a lot of changes in this timeline, but he main character thinks it for the best and doesn't care what will snap back into place. I will have a more eloquent way of putting that when I finish writing this. $\endgroup$ Commented Aug 28, 2015 at 12:08
  • $\begingroup$ @Taemyr You say that like it would be impossible to kill your mother after you've traveled back in time. Hollywood would have you believe that not only is it possible, but if you killed your mother, you'd vanish too, no longer having been born, which is ridiculous but hollywood doesn't bother with particulars like plotholes. $\endgroup$
    – Neil
    Commented Aug 28, 2015 at 12:30

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