“This may sound like cheating, but, well–why don’t we just invent a machine to send us back in time so we can prevent this from happening in the first place?”
Princess Bubblegum points out that attempts at time machines have been made, but unsuccessful. This is where Finn makes his stroke of genius regarding time machines and wish fulfillment:“Yeah, but that’s the thing! You’ve been trying to get them to work […] Maybe you’ll figure it out 30 years from now! Let future me and future you and future Jake do the heavy lifting. They’ve got all the time in the world”.
The trio then go about the simple task of making positive statements, such as “Jake, Bubblegum: I swear we’ll escape from here and I’ll spend the rest of my days working on a time machine”. A few moments later, after some more positivity, the machine appears, with a note from “future old man Jake”. Jake and Finn take off, and we are left with a “to be continued”.
North does not complicate the concept of time travel, instead uses the simple idea that the most important part of wish fulfillment, and changing ones destiny, to answer the what if question, is as simple as making up ones own mind that they are going to do something. This is what I like to think of as “futurecasting”, a way of time travel by communicating with the future through the ideas of a present (or in the case of this issue, the future #1) state of mind. Is it just self-fulfilling prophecy? Sure, but I for one rather enjoy the idea that the power of positive thinking can eventually help us to figure out some of our problems, both real and imaginary.