The Grandfather Paradox

The known universe is comprised of at least four dimensions that we interact with on a daily basis. Although there are theorized to be at least ten if not more.

The first three dimensions we are quite well acquainted with. 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? Einstein said that it was possible and myriad papers, and science fiction novels have been written about it. What would happen if you went back in time and changed something? What if you killed your grandfather before he met your grandmother? What would happen to 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.

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. He lies dead at his feet, his body grows colder and he is buried. 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 causality of that missing person ripples through time and the world changes:  there is no lineage and 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. They are also a person without a connection to the world around them, as they have never existed in this timeline. Maybe now the they feel the true depth and horror of their actions. The traveler has slipped into an alternate dimension and in both dimensions a man was murdered by an unknown assailant, but only in the alternate dimension is that assailant still alive.


Fry inadvertently kills his grandfather and unwittingly becomes his own grandfather. Securing his special place in the Futurama universe. In the award-winning episode ‘Roswell that ends well.’ (21st Century Fox, 1999)


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. So if someone five hundred years from now goes back in time one hundred years and kills 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 time 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.

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.

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