Chapter Sixteen: Marvin Fitzroy's Simple Guide To Time Travel
1.
Let’s start with the simplest case of time travel. Marvin gets in the time machine at 2 o’clock and goes back to 1 o’clock. This creates a second timeline. In the first timeline, of course, there was only one Marvin; nobody got out of the machine at 1 o’clock. But in the second timeline, while the first Marvin is still standing around, a second Marvin gets out of the machine.
The second Marvin doesn’t want to cause a paradox, so he leaves. Thus, the first Marvin gets into the machine, the same way he did in the first timeline. The only difference is, this time, there’s already a Marvin who got out at 1 o’clock. So instead of going back in creating a third timeline, the machine synchronizes the departure with the arrival, and the timeline continues. More on “synchronization” later.
2.
But what if the second Marvin did want to cause a paradox?
Here, the second Marvin finds the first Marvin and tells him not to get in the time machine. When 2 o’clock arrives, no one gets in. That’s a paradox. But what stops both Marvins from continuing to exist?
Well, one other thing is different in the second timeline. When the second Marvin arrives, the time machine also receives a memory of the history that was reverted. The time machine is expecting that the departure from the memory will happen, at the same time as it did before. If it doesn’t, the time machine resets the world to before the arrival happened, with just one change: the memory is now marked as a failure.
In this third timeline, the second Marvin does not arrive, and when the first Marvin gets in the machine… nothing happens. He figures the machine must have malfunctioned or something. If he knows these rules, then maybe he suspects that he caused a paradox, but he doesn’t learn anything about what the paradox was.
It’s lucky that failures just mean nothing happens. Ethel says the physics would be just as consistent if the time traveller got deleted from existence.
2b.
...so Marvin tries again at 3 o’clock, thinking “I’d better be careful not to cause a paradox this time”, goes back to 1 o’clock again, and leaves.In the fourth timeline, the first Marvin once again attempts departure at 2 o’clock. But this time, the time machine has already received a memory of the third timeline, where he failed. His new attempt synchronizes with the failure from that memory. Thus, the machine doesn’t even try creating a fifth timeline where there might be a paradox; it’s already decided.
At 3 o’clock, his new departure synchronizes with the departure from the third timeline. The fourth timeline is now canon.
3.
So how do you make a stable time loop?
Here, Marvin spends two hours brute-forcing someone’s password – trying random passwords until he gets it right. At 3 o’clock, he gets in the time machine and goes back to 1 o’clock, so he can just text himself the password instead of doing all that work.
In the second timeline, the first Marvin receives the password right away. Of course, he still has to get in the time machine by 3 o’clock – otherwise [this will get reset.]
He could try getting in the time machine at 3 o’clock, like the first time. But it won’t work! His memories are different than the original, so the new departure attempt won’t synchronize with the original departure. It’ll cause a reset, just like in scenario 2.
So instead, he gets in the time machine at 2 o’clock. Again, he goes back to 1 o’clock and texts himself the password at exactly the same time. Since the first Marvin is the same in the third timeline as he was in the second, the 2 o’clock departure synchronizes and the third timeline becomes canon. The process of synchronization makes the time machine forget that any departure ever happened at 3 o’clock, so 3 o’clock can now pass uneventfully.
3b.
…of course, it’s hard for a human to get the timing exactly right. That’s why we use scripts – it’s more reliable to program a computer to send a message at an exact time. (If you’re a programmer, you might be thinking, “but even a computer won’t be exactly the same!”. But it’s close enough [that the “same as last time” will will take care of it].)
Here, Marvin messes up the timing. The 2 o’clock departures don’t synchronize, so we reset back into the second timeline; in this fourth timeline, the first Marvin experiences a failure at 2 o’clock.
Luckily for him, he can still make a second attempt. He tries again right away, and succeeds, making the fifth timeline canon.
If he keeps failing all the way until 3 o’clock, then the 3 o’clock departure will get reset; [we’ll be back with a failure in the first timeline. But he can still try again].
Here’s what we think happened on Day 1:
first timeline: Ontoh knew about planned experiment and went there. When Kayla escaped, they followed. Kayla met up with Marvin, and they went to the time machine room. Kayla suspected Ontoh’s presence in the corridor, but couldn’t quite see them. Ontoh tried to come with them into the past (so that there would be 2 copies, so they could watch both KM groups), but KM noticed the mass discrepancy.
2: Ontoh saw KM 1 leave the time machine room, realized stuff was going down, and followed them instead of going to the experiment room. Whatever KM did, it got reverted because Ontoh wasn’t with zeros to cause the mass discrepancy.
3: same as 2 except KM 1 have the right history this time, and are the Ones we heard about. Kayla 0 still suspected stowaway’s presence in the corridor because of imprinting
4: stowaway follows KM 2 instead. This doesn’t cause a paradox because the stowaway had no effect on their behavior thanks to the symbionts and imprinting.
…X: stowaway realizes KM are about to kill everyone “in the know”; rerolling the dice would be better than this. So they alert Simon to cause a paradox
+ 1: doomed KM start planning what to do. They realize that other KM are still showing up. They stop all the other KM from doing anything, wait until near the end, and then go back again to clean it up. Stowaway watches and doesn’t interfere because it looks promising. + 2...: Doomed KM get rid of the other arrivals. (How? Maybe they send back blanks to replace them. Maybe they return to the start and deform the time machine to invalidate them. Maybe PoVs don’t know)Y: doomed KM send the message to us; stowaway following doomed KM. Stowaway induces fear in them so they won’t recommend leaving the building. Stowaway sticks with doomed KM because they might change their mind and do something interesting, while PoVs are instructed to go straight to the time machine and will probably obey, and stowaway won’t attempt to join them because they’ve already been warned about the mass discrepancy, so it would be extra paradox risk for nothing. Kayla 0 still suspected stowaway’s presence in the corridor because of imprinting.
+ 1: we go back and send the message to ourselves; stowaway is now following us (and we experienced “no mass discrepancy” the first time) … ??: Stowaway follows them to go shopping; considers stopping them from going outdoors, but is willing to take the risk because the shopping will help them succeed; follows them and is ready to stop/kill them if they are going to go within view of a Nochli.A: conversation with Astor; as always stowaway recognizes that they are the “latest” and follows them. Fuller overhears the conversation, prevents Kayla’s escape. KM go back to prevent it.
+ 1: KM know they’re in a paradox, kill fuller and find the bug, approach/attack aster, discover the kill phrase. As always, stowaway is following them …Z: KMA go back to do the antidote experiment.
+ 1: stowaway follows experimental group. Assistant texts fuller; Fuller attacks backups and dies; stowaway kills a bunch of people; backups make the plan + 2: experimental group replaced, stowaway trapped. Replay executed, leaving backups’ history the same, so they synchronize with replayers’ arrival. Ethics board convened, decides to cycle the time machine, ending day one Approximate readability: 7.40 (6381 characters, 1466 words, 88 sentences, 4.35 characters per word, 16.66 words per sentence)
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