How to get away with killing your great grandfather with time travel

[MikeandSuch]

So picture this, its 2500 and you want to time travel back to 2300 to kill your great grandfather, this obviously creates a paradox wherein you prevent yourself from being born right?
Well why don't you use your year 2500 technology to create a clone of your grandfather to replace him after (or before?) you kill him? That way you get away with killing your grandfather and can still be born to do so in the future.

Obviously this would be a massively fruitless endeavour since your replacing the person you wanted to kill with an exact replica but regardless it seems like a rather stupid method of fixing your time travel problem.

 

[jedishrfu]

Well cloning technology may still be a crapshoot in the future.

Sci-fi stories look at clones as identical people with near identical thoughts and experiences whereas in reality clones may not behave at all like the original, surely won’t have the same experiences, eat the same foods, and may not really look like the original as they age.

what would be an interesting plot was someone going back to do this and then discovering the guy wasn’t his grandfather that in fact his grandmother had relations with another man, or that one of his parents was adopted, or switched at birth. There are so many strange but true DNA stories to choose from to spice it up.

 

[DaveC426913]

Well why don't you use your year 2500 technology to create a clone of your grandfather to replace him after (or before?) you kill him? That way you get away with killing your grandfather and can still be born to do so in the future.

1] A clone of your grandfather is not your grandfather. So you don't "get away with" killing your grandfather.

2] The offspring of you cloned grandfather is not you.

What are you trying to achieve? Bragging rights at the pub?The paradox occurs because you could kill your grandfather. If time travel is possible, the universe can't prevent this paradox.

 

[256bits]

That way you get away with killing your grandfather and can still be born to do so in the future.

Should work as a plot.
Replace him with the clone after your dad is born of course so you can be born.
You just need a plausible reason for the 'real' grandfather demise.
Did the real grandfather make a decision one time that you disagree with and needs changing to your satisfaction?

Or are you the one with malicious intentions, with the cloned grandfather replacement as just a trial run for more replacements towards your goal, with the world being none the wiser with no obvious murders.

 

[Halc]

So picture this, its 2500 and you want to time travel back to 2300 to kill your great grandfather, this obviously creates a paradox wherein you prevent yourself from being born right?

Why does grandpa always have to get it? Why can't you just go back one minute and weld the door to the time machine shut? Paradoxes are trivial with time travel, so why bother with the elaborate grandfather scenario. You don't even know for sure he's your ancestor. Plenty of illegit kids unaware of their real father. Can't be sure. But the time machine a minute ago is sort of a necessary part of the plot.

 

[DaveC426913]

Why does grandpa always have to get it? Why can't you just go back one minute and weld the door to the time machine shut? Paradoxes are trivial with time travel, so why bother with the elaborate grandfather scenario. You don't even know for sure he's your ancestor. Plenty of illegit kids unaware of their real father. Can't be sure. But the time machine a minute ago is sort of a necessary part of the plot.

Grandpa is just a common cautionary tale. It's tradition.

Still, a welded door can always be de-welded - at least in theory.
But story-listeners easily intuit that, once a person is deaded, they can't be de-deaded. It's irreversible*.
*outside of time travel of course.

 

[Halc]

Still, a welded door can always be de-welded - at least in theory.

The welded door is completely unnecessary. If I'm contemplating the useless action of killing my grandpa, clearly creating a paradox is my goal. So I travel 10 seconds back and greet myself, and the two of us walk away arm in arm, paradox achieved since nobody was ever sent back.

 

[DaveC426913]

The welded door is completely unnecessary. If I'm contemplating the useless action of killing my grandpa, clearly creating a paradox is my goal. So I travel 10 seconds back and greet myself, and the two of us walk away arm in arm, paradox achieved since nobody was ever sent back.

Agree. I'm simply pointing out that the grandpa thing is instantly intuitable by anyone.

Your idea of traveling back ten seconds confuses me, until I think about it. I suppose what you mean is your time traveled self stops your other self from even using the machine. Technically accurate, but not elegant.

 

[DrStupid]

If time travel is possible, the universe can't prevent this paradox.

According to the Novikov self-consistency principle it can and it would. The gradfather paradox just results from contradicting assumptions (killing the gradfather and not killing him). I have never seen a time-travel paradox that is not based on two different versions of the same event.

 

[pinball1970]

So picture this, its 2500 and you want to time travel back to 2300 to kill your great grandfather, this obviously creates a paradox wherein you prevent yourself from being born right?
Well why don't you use your year 2500 technology to create a clone of your grandfather to replace him after (or before?) you kill him? That way you get away with killing your grandfather and can still be born to do so in the future.

Obviously this would be a massively fruitless endeavour since your replacing the person you wanted to kill with an exact replica but regardless it seems like a rather stupid method of fixing your time travel problem.

Its science fiction so everything is fine.
Build a worm hole, go back in time when your grandad is already conceived then kill his dad.

 

[Eclair_de_XII]

what would be an interesting plot was someone going back to do this ans then discovering the guy wasn’t his grandfather that in fact his grandmother had relations with another man, or that one of his parents was adopted, or switched at birth.

You mean like Futurama.

 

[BWV]

If you later hookup with grandma then everything works

 

[pinball1970]

If you later hookup with grandma then everything works

That's when everything is as wrong as it gets in my book

 

[some bloke]

Not really 100% on the question here but the topic to be discussed is always an interesting one.

Firstly, you have to consider the type of time travel you want to use - and this being sci-fi, there's a few to choose from:

Option 1: if you kill your grandfather, you fade away like in back to the future, because you would never have existed to go back. This one's the least scientific one, because it fails to follow the concept of "cause and effect" - the state of the time traveler is being affected by the future, not the past.

Option 2: If you kill your grandfather, you will never be born, but that's okay as you're alive now, regardless of how it happened. If you can travel back to the future, then you will continue to live, but no-one there will remember you as you wouldn't have been born. The time machine will only exist there by virtue of you taking it forward through time to get there - you were never alive to invent it. This one (to me) seems the most realistic, as the ocntinuity of your memories and of those around you will not need adjusting. You would remember a world where your grandfather lived to concieve your dad, and others will remember a world where you killed him before he had kids. This could well be used as a plot device for covering up the creation of a time machine - like erasing your tracks behind you, you could conceive of a time machine, design it, make it, then go back in time to kill yourself, making your time machine unique and uncopyable.

Option 3: If you go back and kill your grandfather, the world splits into a multiverse and you will be trapped in the wrong one - this is fundamentally the same as the above, from your perspective. It generally doesn't need to be explored, as we have no proof of the multiverse theory, so couldn't tell if you were in one or not.

Option 4: If you try to kill your grandfather, everything you attempt will fail because it already took place and as such we know the outcome. If you try to run him over, he'll dive out of the way and meet your grandmother, if you try to shoot him, you'll give him a scar which you remember from pictures. This is used to good effect in the book "the strange affair of spring-heeled jack":

Spoiler: strange affair of spring heeled jack spoiler

A man goes back in time to prevent the attempted assassination of queen Victoria by his ancestor (both called Edward). when he intervenes, he is struggling with him when he hears someone shout "Edward, No!". They both turn, slip, and he impales (ancestor)Edward's head on a railing. he then tries to go back and stop himself from killing Edward, but is late, and runs in shouting "Edward, No!", then realizes he is the reason why they turned in the first place and why Edward is dead. So continues a very good time travel plot!

I prefer Option 2. Think of it in a small scale - quantum randomness (from my very limited understanding of it) has the chance of electrons appearing from nothing. If that electron appeared from the future, it wouldn't affect the present, because its leaving wouldn't have happened yet. All it can affect is the future of it and its surroundings.
Now make that a person. If a person popped into being on a corner one day, their presence there is not going to be affected by the future, even if that's where they came from.

Think of it as this: The past forms the present, and the future doesn't exist. The past only exists because the world remembers it - The present exists because the past made it, and thus the present is proof of the past's existence. The future is assumed to exist because we are aware of how the present becomes the past, so anticipate that there are more presents ahead for when our present becomes the past.

If, suddenly, everyone on Earth forgot the existence of World War 2, for example, and every book containing it suddenly didn't any more, all evidence of it happening was removed, and no-one remembered they had ever existed, then no-one would ask "what happened to WW2" because no-one would know it had ever happened in order to be missed. The only reason the past exists is because of the evidence it leaves behind.

As such, if you come from the future, you arrive somewhere where all that there is is the present and the evidence of the past, you are no different from someone pinging into existence with delusional memories of events which never happened.

Scenario 1: you go back in time to the year 2300 to kill your granddad before he murders a dozen people in 2302.
Scenario 2: a person with your genetic makeup appears from nowhere in the year 2300, with memories of having to kill your grandad before he murders a dozen people in 2302.

Considering these scenarios are functionally identical - bar the "where did they come from" question - which is a paradox?

 

[stefan r]

There is a nice video called "The History of Time Travel". I saw if free on amazon prime. Here is the trailer.

 

[Rive]

How to get away with killing your great grandfather with time travel

Well. As a salute to Occam: if you can get away with that the first I would think of is, that you did not managed to find your actual grandfather

 

[Lren Zvsm]

Here's an image that should help first-time writers of time travel stories: