The Grandfather Paradox - 60-Second Adventures in Thought (2/6)

A well-known story that questions the logic of time travel.

(Part 2 of 6)

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[obbeachbum]

Oh that handy multiverse. Whenever things get sticky like the cosmological constant, just pull it out, rinse and repeat. 

[VOLKHVORONOVICH]

In line with the Grandfather Paradox is a tale of a man who grew up hating his father. The father did not seem to love his wife and was sometimes unaccountably cruel to her. He beat the boy at times and seemed to have a particular vendetta against the child's budding scientific talent.

When he is a young man his mother dies. The father grieves but does not seem surprised—almost as if he knew it was going to happen. The son resolves to avenge his mother, whom he is certain that his father has in some way caused her death.

A few years later he plants a bomb in his father's car. When the father turns the key and hears the tell-tale click, he cries out, “Oh, no—he did it today! Might as well get it over with.” The car explodes and the police never discover the culprit.

With no interference from his father he is free to pursue his scientific interests with a vengeance. He has a goal now. Discover time travel, go back in time, kill his father (the man he hates more than anything in the whole world) before he can marry his mother and make her life a living hell.

And he succeeds! He sends himself on a one-way trip to the past. Locates his father and kills him as he makes his way home from work. The murderer is surprised to see that he has not faded out of existence because he's prevented himself from ever coming into existence in the first place. He sets himself to take his place in his new world.

A few years pass. He finds a girl, marries her and settles down. Their first child is born and he congratulates himself for changing history, and triumphing over fate.

A victory short lived when he sees the reflection of his face in the glass of the maternity ward as he is gazing upon his new born son—it is the face of his father. He has gone back in time and become his own father! He has not changed time—he has only caused it to happen. The man he killed was not his father, but someone completely innocent.

He cannot bring himself to touch his wife any more. And he sees the interests of his son veering toward the scientific. He knows the boy will eventually invent time travel. He tries to stop this, smashing radios and television the boy creates. He knows it is fruitless but he can't stop from trying.

He is not surprised when he finds out his neglect has killed his wife. He knows his son will blame him for her death. He knows his son will now be actively planning his own death—and there is not a single thing he can do about it, because everything has already been done. The script has already been written and he can't change it.

So when he hears the fatal click as he turns the key, though he cries out with fear of what he knows will happen, he knows he has no other choice. “Might as well get it over with.”

[This story first appeared in one of the old Warren Magazines probably from the 70s, possibly Vampirella, and in my opinion was friggin' brilliant!]

[Drakus]

Traveling back in time should be defined simply as traveling to an alternate universe in which all events that took place in history occurred exactly the same way up to the moment you arrived in the past. As soon as you arrive in the past, events unfold differently due to the butterfly effect. You wouldn't disappear if you caused a grandfather paradox because that's not your grandfather. He's a different person on a different timeline with a different future. The timeline you came from is separate from this new timeline you live on and your existence is not dependent on how events unfold on this new timeline. Grandfather paradox solved ... I think.

[davewilliam]

How To Travel Back In Time
1. Build circulating light beams machine.
2. Use circulating light beams machine to travel to year 1985AD.

[Unknown-sgtv]

Time Travel Rules short version
1. Only observe don't change history.🍐
2. Wear clothes from that time period.🕵
3. Only spend 1 minute in the past.🕵🕓
For those who want to time travel.

[davewilliam]

How To Travel Back In Time
1. Make digital clock five hours backwards.

[kookookachu]

This goes into something called the bootstrap paradox. Where you cause event A which causes event B which causes event C which causes event A. Basically, he wouldn't be able to kill his grandfather since time is an endless loop and anomilies such as this one don't have an origin thus pulling himself up by his boot straps.

[dhvsheabdh]

A difficult question. While some may say "obviously not", others may disagree. Einstein said that as long as the events are not linked causally, then there can be a change of opinion of when it actually happened, as observed by a high speed observer, and a stationary observer, both relative to the observed object.

[CookinginRussia]

Much simpler solution. You don't LEAP back in time. You GO back in time. So the very first second you actually go back in time is the moment before you went back in time, and thus you would still be going forward in time. You would be stuck in an infinite loop at the present moment you went back in time. There - no paradox.

[MHGenesis]

I don't see why it's a paradoxon.
If you travel back in time, you have already changed the past, so what's happening from that point on, will be entirely different anyway. Because even if you would kill your grandfather, then why should there be something happening to you? The atoms that you consist of, would still be there, you would just change the world that you are currently in. So you basically would create another universe or an alternate line of events in the universe. In general, travelling back in time would change everything, because, if it's true that quantum mechanics are based on probabilities, the events after travelling back in time, would need to be determined again. So if the outcome of quantum events are really "random", there would be a lot of different stuff happening.
I think it would be stupid to assume that what happens in your life during the current time, would already be the cause of what you did after travelling back in time, it doesn't make sense at all.
Not to forget that it's probably not possible to go back in time.
It's just logical, it wouldn't need a parallel universe, it would just change the current universe.

[davewilliam]

How To Travel Back In Time
1. Make Year 1999 calendar.
2. Buy year 1999 clothes and wear 1999 clothes.
3. Buy year 1999 technology and have year 1999 technology.

[lcbreezyl]

I always had this question but a little different.
What if you went back in time and meet yourself as a kid? You would have already meet yourself and known that you were going to travel back in time when you get to a certain point in your life.

[ASSHOLELA]

youre thinking deterministically. in the quantum world, a cause X will not always lead to a consequece Y.
for example, if a nucleus decays neutrons may not always be emitted.

[youwatchmuchtv]

@MrTh1rteen How could we go back in time? I mean, if we were to go back in time before a Time traveling device was created, wouldn't that create a singularity, or a paradox right then and there?

[leviticusrich]

For a multiverse theory, how would a grandfather paradox prevail?

[thlkle]

Time travel in this case would mean "transport" the particles that constitutes your body to the past. So you would be already altering the past as you travel backwards, since all events related to those particles would also change. You'd be isolating those particles from cause and effect events as history is being altered. In a sense, when you land in the past, you're no longer the result of your parents, but the aglomeration of those particles in another timeline, fully formed and with knowledge of your own timeline, that no longer exists. It would be possible that your grandfather no longer exists, since events related to these partcles you're moving through time could also be related to his existence in the past. But assuming he still exists, and your parents still are born, their child could have all your traits but no longer be you!

Let's say you eat an apple and want to travel back immediately to eat that again. Either that apple no longer exists or the particles that constituted the apple you ate aren't present in the apple you'll find in the past. In short, you'll never be able to eat the same apple twice. It might have the same shape, smell, taste, but ain't the same.

The problem with the paradox is to assume time as an entity separated from space. Time travel is impossible because time, in this sense, doesn't even exist! You can't rewind reality as if had a timescale, what you actually would be doing is to undo cause and effect events to return reality to its previous states while isolating the particles that constitutes you from the process. It's more like erasing the present than going to the past.

[ASSHOLELA]

Normally, we should see product particles, such as a electron and antielectron, from an inteaction of a source particle, such as a photon giving up its energy.
But since the space time geometry of quantum foam is irregular, containing wormholes into the past, it could be likeley that a particle from now travelled into the past, interacted with the photon, causing it to vanish, and then we observe that the product electrons appearing from nowhere.

[doltBmB]

Novikov has solved the problem, by the way (together with Kip Thorne, creator of Interstellar, the movie was originally going to touch on the subject but Nolan had other, more pretentious ideas) all grandfather "paradoxes" have an infinite number of non-paradoxical solutions, one of which will always be the case. In other words, it's mathematically self resolving.

[Waaqawaaqa]

Well, what if you just wanted to do something pointless like move a rock.Would this still apply?
I know it's a stupid question but it's the only way I can figure this out.

[manfreako]

Time travel is currently possible within a 24 hr radius in some form. all you need to do is go through the time zones backwards or forwards.