4 ms·

If there are time travellers from a future, it isn't our future, and this isn't their past - otherwise causality doesn't work. Instead if you travel back in tim

If there are time travellers from a future, it isn't our future, and this isn't their past - otherwise causality doesn't work. Instead if you travel back in time you travel to a point, which immediately bifurcates into a new reality. I like to think that we're all time travellers, collectively collapsing the universe's wavefunction through will alone... And now I'm onto determinism so I'll shut up.

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bentcorner 12y ago
What's to say that we're not existing in a reality created by a time traveler? A new-reality model of time travel only affects the viewpoint of the time traveler.
- Chronic28 12y ago
  Who cares if our present was altered by a time traveler. We can't tell.
dllthomas 12y ago
Causality could be a generalization that breaks down in extreme cases, like Newtonian mechanics.
- ludwigvan 12y ago
  This is scary.
  - dllthomas 12y ago
    Why?
maxerickson 12y ago
We only have a very firm belief that causality is inviolate. I guess there isn't a way to prove that it is.
melvinmt 12y ago
Who says your reality is the same as my reality already? :)
bradleysmith 12y ago
>I like to think that we're all time travellers, collectively collapsing the universe's wavefunction through will alone... And now I'm onto determinism so I'll shut up. I like that. Though I would think it is not 'will' but 'life' that interacts with universal determinism, through physical expression of information over time. How that information will express itself (how gene-information will translate into physical realities in each moment) seems in the realm of the unknowable (like turbulent flow or other instances of Lorenz-y chaos in the Universe), and consciousness as one of those gene-expressions makes this even more loopy. But I've wandered into Leary-esque fascination with faults of perception lately, which ought to stick to the human-describing world of psychology, so I should probably shut up too.
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cgriswald 12y ago
Novikov's self-consistency principle implies that we can change the past as long as we don't know it's been changed. (Well, maybe more accurately, the time traveller has "always" done whatever it was he did in the past.) So even if causality is a requirement, it isn't necessarily violated. Likewise, lots of time travel in fiction actually has the hidden assumption of a second time dimension. If a second time dimension existed, causality could be maintained along that dimension while seemingly broken in the time dimension we know and love. And there's always the possibility that causality isn't a given and is simply how we experience the universe. Just because it has always been observed and it makes intuitive sense doesn't mean it is always true. :)

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bentcorner 12y ago

What's to say that we're not existing in a reality created by a time traveler? A new-reality model of time travel only affects the viewpoint of the time traveler.

Chronic28 12y ago
Who cares if our present was altered by a time traveler. We can't tell.

dllthomas 12y ago

Causality could be a generalization that breaks down in extreme cases, like Newtonian mechanics.

ludwigvan 12y ago
This is scary.
- dllthomas 12y ago
  Why?

maxerickson 12y ago

We only have a very firm belief that causality is inviolate. I guess there isn't a way to prove that it is.

melvinmt 12y ago

Who says your reality is the same as my reality already? :)

bradleysmith 12y ago

>I like to think that we're all time travellers, collectively collapsing the universe's wavefunction through will alone... And now I'm onto determinism so I'll shut up. I like that. Though I would think it is not 'will' but 'life' that interacts with universal determinism, through physical expression of information over time. How that information will express itself (how gene-information will translate into physical realities in each moment) seems in the realm of the unknowable (like turbulent flow or other instances of Lorenz-y chaos in the Universe), and consciousness as one of those gene-expressions makes this even more loopy. But I've wandered into Leary-esque fascination with faults of perception lately, which ought to stick to the human-describing world of psychology, so I should probably shut up too.

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[deleted]

cgriswald 12y ago

Novikov's self-consistency principle implies that we can change the past as long as we don't know it's been changed. (Well, maybe more accurately, the time traveller has "always" done whatever it was he did in the past.) So even if causality is a requirement, it isn't necessarily violated. Likewise, lots of time travel in fiction actually has the hidden assumption of a second time dimension. If a second time dimension existed, causality could be maintained along that dimension while seemingly broken in the time dimension we know and love. And there's always the possibility that causality isn't a given and is simply how we experience the universe. Just because it has always been observed and it makes intuitive sense doesn't mean it is always true. :)