Preface
I have an idea for a time travel story or setting with a soft sci-fi foundation but with hard sci-fi rules to subvert and avoid tropes and cliches. I am in the process of writing a page for that idea but I'm still deliberating how I should structure and explain the idea's elements.
There is one effect though which I found particularly important to the idea, that being the subject of this page. I had written out everything but decided to upload it as a separate page for the following reasons:
- I feel my explanation is lengthy and would detract from the time travel idea
- The Strong/Weak Butterfly Effect can be used outside of my time travel story idea, leading to the third point...
- This is something I wish to share so others can identify it when reading/watching stories or consider when writing their own
The Butterfly Effect
The term "butterfly" effect came from Ray Bradbury's short story "A Sound of Thunder". You should be familiar with the concept. but if you're not, it's a case where a miniscule change in one point in time causes a significant change at a later time through a series of events brought about by that tiny change. However, I feel many writers (even Bradbury himself) vastly underestimate the butterfly effect.
Consider a pair of double pendulums. Now consider how a miniscule change would affect a more complicated system. Every atom in the universe is like a double pendulum and you don't even have to touch the pendulums to give it that push.
Speaking to someone in the past would interrupt whatever action or thought they were in at the moment. This would change when, where, and how they would interact with other people later on, who would themselves interact with the world differently had you not been in the past.
The degree the butterfly effect has as a result of time travel leads to my distinction of the effect into a Strong and a Weak variant.
The Strong Butterfly Effect
The Strong Butterfly Effect describes the effect when applied to its logical extreme.
With time travel, the Strong effect is distinguished where absolutely any form of time travel will irreversibly change the timeline from the point of time travel onwards.
When physically traveling to the past, the action itself would be enough to change history, as the displacement of air from your breath or the grass you step on would create a physical cascade. This doesn't have to be physical too, as magically influencing someone's decision in the past can have an equally immense effect as talking to them in person.
As for future time travel, (bear with me) the future you travel into is one in which you had traveled into the future instead of one where you had stayed in the present. Thus, there is a new timeline where one person and their effects are absent.
There would be no conventional way to undo the changes and the Strong Butterfly Effect lends itself to time travel paradoxes. In an example invoking the grandfather effect, changing the past (even within the time traveler's own life) would change the circumstances behind the time traveller's existence, their time machine, their intention of time traveling, or at the very least what intentions they have when time travelling. This would then change or prevent whatever action had been done to change the past, causing the paradox.
Of course, the obstacle the Strong Butterfly Effect poses can be subverted based on how one chooses to resolve the resulting time travel paradoxes. One example is a "loop" where a trip through time takes said trip and its effects into account, thus creating a single, consistent timeline. I touch upon another idea below.
The Weak Butterfly Effect
The Weak Butterfly Effect describes all other applications of the butterfly effect. This is where liberties are taken to allow changes to timelines to be reversed.
There is not much to say about this aside from the fact it's the logical negation of the strong butterfly effect and that this form of the butterfly effect is seen more in popular time travel media.
