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A Nonlinear History of Time Travel (nautil.us)
73 points by dnetesn on Oct 1, 2016 | hide | past | web | favorite | 19 comments

The article is... Definitely longer than it needs to be. Aristotle's "final cause" - that a thing could be considered to be caused by the ultimate purpose for its existence; the beauty of art, as an example - is pretty interesting.

That said, I really just wanted to link some interesting thinking / writing on time travel, that treats it pretty well:

- Primer (http://www.imdb.com/title/tt0390384/)

Probably the most popular. Engineers accidentally invent time travel, and then VERY CAUTIOUSLY begin to experiment. Takes more than one viewing to follow. Something resembling multiversal-style TT.

- Time is Like a River (https://www.fictionpress.com/s/3138462/1/Time-is-Like-a-Rive...)

A little girl discovers she can time travel, but cannot make paradoxes, but can still make choices... Although the writing itself is not the best, the gradual exploration of the ability - how to use it, what is possible - is incredible. Single timeline, zero paradoxes, uses something like self-reinforcing probability as the underlying "rule"

- Continuum RPG http://www.aetherco.com/continuum/

"The universe doesn't prevent paradoxes, people do". An attempt to make a playable single timeline, zero paradox, time travel RPG. The underlying reality is extremely well thought out, presenting reasonable ways for such a universe to function, although sacrifices are made so that humans can actually successfully play the game.

There's also Achron, an RTS game that uses time travel as a key mechanic. There's a single timeline, but it's malleable.


I always think of the universe as multiverse, so time travel doesn't seem paradoxical to me.

That is just because you are not thinking carefully enough about the consequences of the rules you are making up. Start really thinking about it and you will pretty surely discover a lot of contradictions, paradoxes and so on.

Not really. There are three basic ideas with time travel. Either time is independent so if I go back a second a pick up my wallet I can come back and have two wallets ( aka multidimensional time).

Consistent where doing that only works because a future time traveler took my wallet so I just end up with one (Self consistent aka Harry Potter time travel).

And one way which basically means if I go back there are now two of me and I have to go forward the slow way. Which is separated from the first example by erasing the future when you travel back.

Paradoxes are only an issue in the second example.

Your first and third scenario seem not to honor conservation laws, one can probably build some nasty consequences out of that. Or what happens to the matter occupying the space you are about to appear in, where does it go? In the third scenario it can not simply switch places with the matter from the future because that would kill the asymmetry of that scenario and provide a way to send stuff to the future. I was not simply talking about you killing your younger self. To have any real merits one has to analyze a time traveling scenario with the same mathematical rigor as our normal physical theories. But I never thought much about about time travel because it is such an hypothetical idea and therefore my example a probably pretty bad but I hope you get the idea of what I am aiming at.

Conservation laws are man made, if the underlying universe does not follow them then so be it.

As to other interactions their are a great many possibles but they don't mean much. For example restricting things so only light can move though time does not change the underlying options in terms of information and paradoxes.

PS: Mathematical rigor is again a human idea, our universe could be absolutely random and we would have no way of knowing. At best we can say that seems unlikely.

Well, we can also just say the same things about paradoxes of all types. Partially the point of science-fiction (and science/philosophy) is that our thought experiments have parameters consistent with our current knowledge of reality if no other restrictions are specified.

I've been planning on writing a novel based on that for about twenty years now. I've even started it a couple of times. I certainly hope someone "steals" our idea and runs with it.

Michael Crichton did it.

It's how the time machine worked in Timeline.

If I remember correctly, the company sending people back through time (really to a parallel universe) didn't even know how/why the receiving machines were appearing.

It also happened on Sliders, they visited worlds that were ahead or behind Earth Prime.

Not exactly the same idea, but Steins;Gate deals with time travel as travel between parallel universes in a similar way.

One fun way to almost-disprove time travel (so far) is that there is no evidence that anyone is doing google searches for things they could not have known beforehand: https://arxiv.org/abs/1312.7128

Infinitely more fun than this article is the taxonomy of time travel plots at SF Chronophysics. The whole site is worth a look around:


hmm... tl;dr anyone? I wanted to like this, but am finding it rather confusing and unstructured so far.

It's not actually _that_ nonlinear - follows philosophy on time travel through Aristotle, then Godel & Einstein and then through to Hawking.

That said, the nonlinear part: picks out every now and again a pop culture echo of the current theory being discussed, like the Terminator or the Time Machine or Heinlein's "—All You Zombies—" i.e. the one where a person is their own mother, father, son and daughter. (I really wish it talked about Looper or 11/22/63 or Rick & Morty.)

Discusses whether time travel is logically possible, how paradoxes could ever work, causality - the overall tone being time travel is basically impossible as we know it but boy is it ever fun to think about.

I'm feeling the same way.

Welcome to non-linear history during time travel.

Edit: for those downvoting, the article linked is actually a pretty good introduction on why time travel may be self evidently impossible through simple logic (we already know the event didn't happen, so it can't go back and happen), but also may be self-evidently possible if certain criteria is met first (specific fuckery involving time-like closed loops and multiverse theory, which means, essentially, history can't be trusted or multiple concurrent histories can't be trusted, respectively).

So, yes, it is confusing to need to think about logic in the terms presented by the article.

I believe we just don't like the way the article is written and not the ideas within.

Excerpt from a book. Humans discussions and writings on time travel

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