A phrase that often comes up when discussing time travel is the Grandfather Paradox, and no, it is not related to the notion of loving gramps but hating his politics. It is the idea that you can travel though the dimension of time and have a direct effect on your own existence, for better or worse.
The Four Dimensions
The known universe is comprised of at least four dimensions that we can interact with daily. Although there are theorized to be at least ten if not more. Those are quite esoteric, and as I stated before, there will be no math in the series.
We are quite well aqquainted with the first three dimensions: depth, breadth, and height. X,Y,Z. Up/Down, Left/Right, Forward/Back. The forth dimension, that we are also well acquainted with, is the dimension of time. We know that it runs forward. It runs faster or slower depending on gravity, speed, or how much fun you are having at the particular moment. It is relative to a fault, but we cannot move backward through it.
But what if you could? Theoretical Physicist, and fashion icon, Albert Einstein, said that it is possible and myriad papers and science fiction novels are written about it. What would happen if you went back in time and changed something? Perhaps you accidentally killed your grandfather before he met your grandmother? How would that affect you?
This is what is known as the “grandfather paradox”. If you could go back and kill him, how could you do it? You’d never been born.
Sticky Situations With Time Travel, or Fun With The Grandfather Paradox
Or could you? Hypothetically, if time travel backward is possible, then you should be able to affect and change the past. The grandfather paradox should have three outcomes:
1. The time traveler goes back and kills their grandfather. The universe literally unravels as this causality paradox breaks the fabric of spacetime. All is lost. You can forget about seeing the next Spiderman reboot.
2. The time traveler goes back and attempts to kill their grandfather but something prevents that from happening. They run out of bullets. The grandfather is a Terminator and just won’t die. The traveler is simply paralyzed. Who knows, but its is something.
3. The time traveler goes back and kills his grandfather. Much to the dubious satisfaction of the grandchild. Nothing apparently happens and the traveler goes back into their present, only it is markedly different. The actions of that missing person ripple through time and the world has changed: there is no lineage, but the absence is also not recognized. The grandchild now lives in a world where they are the only person who recalls his parents or their grandfather as an old man.
Worse still, they are also a person without a connection to the world around them, as they have never existed in this timeline. Maybe now they feel the true depth and horror of their actions. The traveler slipped into an alternate dimension and in both dimensions, a man was murdered by an unknown assailant. However, only in the alternate dimension is that assailant still alive.
Is the Grandfather Paradox Even Possible?
Given the complexities stated here, we can surmise that one of these options is not possible. You cannot go back in time, kill your grandfather, and unravel the universe. If it was possible it would have already happened. Destroying the timeline at any point would destroy the entire timeline. If someone five hundred years from now went back in time one hundred years and killed their great-grandfather the universe would be destroyed in both directions. Time moves forward and backward simultaneously. Like a wire between two telephone poles, once its snaps, both ends slack.
We are then left with the last two possibilities: You simply cannot alter the timeline. Which would lead to a fairly boring adventure if you were to go back but be incapable of affecting any change. But does lead to some amazing possibilities of studying the past since your actions have no consequence. Or you slip into an alternate dimension in which you are homeless in a possibly alien world relative to you. You are in an even worse situation that whatever drove you to the insanity of grand-patricide in the first place.
From Bad to Meh, or Worse
The exploration of spacetime could offer many educational benefits to explore how we got to where we are currently. Or could offer a literal self-imposed prison in an almost familiar world.
In any case, maybe it’s best to avoid any of your ancestors in any time. Just in case.