Time paradox


Imagine an inventor who has a robot servant able to predict the future, even if just for a few seconds. The robot is programmed to follow its master's wish as soon as it becomes aware of them. The master is eating dinner, and the robot knows that just a few seconds into the future, he will say "pass the salt, plase". So it gives him the salt. But now when he have the salt, he will never ask for the salt in the first place. And since he will never ask for it, the robot will never receive the order from the future, and will therefore not give it to him. But if he doesn't give him the salt, he will need to ask for it, and then we are back to start.

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Well, the salt paradox certainly makes a change from the grandfather paradox.

ant-mac

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Multiple timeline explanation.

When the robot passes his master the salt, it creates a new timeline in which events play out differently. However, there is no paradox because the impetus to pass the salt originated from knowledge of the original timeline, which still exists in a parallel reality.


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If I could stop a rapist from raping a child I would. That's the difference between me and god.

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At least they could add some variation to it, like replacing the grandfather with the grandmother now and then, or even the parents. And use castration or sterilization instead of murder.

Another example from Ted Chiang:

In his short story “What’s Expected of Us”, Ted Chiang gives an account of a futuristic world where a certain technological device seemingly demonstrates that people do not have free will.

This device, referred to as a ‘predictor’, has a press able button and a green LED light, which functions as a signal. The signal flashes if and only if the button is pressed. The interesting characteristic about this signal, however, is that it flashes one second before the button is pressed. This is made possible by a ‘negative time delay’ capacity in the predictor, which gives it the ability to send information backwards in time. The specific information that the predictor is able to send back is that the proposition ˹X presses the button at t˺ is true. This information is sent, from the future, to a time one second prior to the pressing of the button (which is the same time the information is sent), causing the green LED light to flash. Assuming the device is functioning properly, the information is sent (and the LED light flashes) if and only if the button is pressed it is impossible for one to press the button without the light flashing just prior, just as it is impossible for the light to flash and the button not be pressed. Any attempts on the part of the user to violate the above mechanistic principle, perhaps by attempting to wait for the signal to appear and subsequently refrain from pressing the button or to very quickly press the button before the signal appears, will prove to be futile.

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The only reason to ask for the salt is because he has not been given it yet. Which mean that somewhere there is a parallel timeline where he needs to ask for it, and the question therefore remains what the robot from that timeline have not done anything yet.

And parallel reality feels a bit like cheating. The grandfather paradox could be explained the same way, but then it would no longer be a paradox.

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That's exactly the point of the parallel timeline hypothesis; it's a way to resolve the paradoxes of time travel.


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If I could stop a rapist from raping a child I would. That's the difference between me and god.

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"That's exactly the point of the parallel timeline hypothesis; it's a way to resolve the paradoxes of time travel."

It does , but I dont like it - new universes springing up all over the place everytime someone has a vague thought!
A whole new universe! full of people also making new universes
its just not sustainable!

Its easy to simply say "every decision is played out in a parallel universe" ... theres just too many universes! it would turn the "multiverse" into a boiling chain reaction exploding with new universes!

...unless you mean these parallel timelines are only created from really significant events - like time travel meddling - in which case fine :)

edit: i see the 2 posters below also agree!

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To me, it resolves nothing. The idea that changing an action results in an alternate reality is absurd. Perhaps you'll recall the sort of energy required to create our universe--for example, the incredible energy posited in the Big Bang theory. How could my decision to turn left instead of right generate the energy to create an alternate universe?

Nor does the idea that infinite alternate universes already exist, and that time travel not only traverses history, but also crosses the boundaries between the alternate realities. If all possible universes already exist, then everything is meaningless. If I time travel to an alternate past where I am able to kill Hitler before he takes power, so what? In my original reality, Hitler will still have lived and still have caused the same evils as he did before my futile effort.

So, as far as I'm concerned, the parallel timeline does nothing to resolve the problems of time travel stories. In the end, I don't think it's possible to write a time travel story that hangs together logically when closely analyzed. Sometimes the story is sufficiently fun, sufficiently worth it, to justify ignoring the anomalies for the story's sake. However, time travel stories necessarily contain irresolvable paradoxes, because time travel is, itself, absurd.

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How could my decision to turn left instead of right generate the energy to create an alternate universe?
Alternate universes and alternate timelines are not necessarily the same thing (although it can vary from fiction to fiction).





"A big ball of wibbly wobbly, timey wimey stuff" The Tenth Doctor explains all.

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What an earth is a timeline? I mean physically how does it exist?

Yes, friends, governments in capitalist society are but committees of the rich to manage the affairs

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Time would bend. One where the salt was given without ordering it.

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