Watch this wonderful whiteboard mapping of time travel in movies

Originally published at:


Based on that screen cap alone, it looks like I need to watch Primer.


Primer is basically impossible to follow on the first viewing unless you have a complicated flow chart handy.


it is a great flick and by most standards the definitive time travel flick.

Edge of Tomorrow might be my favorite time travel film…but my favorite time travel anything was the DS9 Trials and Tribble-ations


Primer is one of my favorite movies. As far as i can tell, it was made by two engineers with basically no budget.

But they didn’t dumb anything down for you. The creators trust you to have the tiniest amount of intelligence, which is unusual in movies.

Love it. I might watch it on repeat again tonight.


XKCD made a similar reference to Primer over here:

I think it’s hugely overrated, frankly. The aesthetic and ideas are refreshing, but there are some bits which just plain don’t make sense and aren’t going to make sense no matter how many times you watch it.


Primer was a really great time travel movie.


There was a time where the Prisoner of Azkaban example (“basic logic works”) would simply be summed up as “nothing moves in spacetime”. the universe and all worldines in it is one static object, even if we perceive only a changing cross-section at a time. Time-traveling you was always there, and when you go back you can’t save Lincoln or kill Hitler, because you already didn’t.

Unfortunately, that’s the most taxing sort of story to write, so pretty much no one does. And even those who try either by accident or for aesthetic effect introduce impossible objects, bootstrapped characters, or other subtle paradoxes.


Smarter people than I have explained it. The movie takes place over nine distinct timelines:

I love this movie but I feel privileged in that I saw it the first time without knowing a single thing about it. It totally blew my mind.

Edit: here’s a pretty-great written explanation:


I’d like to hear his take on the Prince of Darkness.
There was no actual time travel by people but signals are sent back from 1999 to sleeping brains (as far back as the foundation of the Catholic Church possibly by tachyons) to affect causality.
I guess the logic goes if they are sending the signal the Prince of Darkness couldn’t have broken out because they are sending the signal.
An end run around causality.
Some of the ideas in this movie have given me sleepless nights.

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Which is why I hated Harry Potter and The Cursed Child. It takes the best time travel story (realism-wise… in a children’s magic book… yeah, weird) and completely betrays everything it stood for.

The diagrammatic conventions he created are very clever, and useful.

By the way, anyone who really likes time travel plots should watch Korean television. The number of Korean shows - romances, comedies, action shows, whatever - with time travel themes is insane.

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Rivers timeline, best timeline…

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Frequency was kind of corny but it was another story that involved sending signals back in time rather than people or physical objects. That premise might not be any more plausible from a physics & causality point of view than traditional time travel movies but it still felt more plausible.

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One other thing all these movies have in common: Bruce Willis was dead the entire time.


Glad you think so too, I’d hate to be the only one who didn’t like Primer. Then again I thought that Timeless TV show was great popcorn fun; their inability to fix anything made it subtly different to Quantum Leap, of which you could watch the pilot and last episodes and be happy. I’m not saying there weren’t great episodes in between, just that it all rounded itself off nicely.

For a different take, you could try this -
It’s a sort of sweet take on time travel: yes, another Japanese schoolgirl, yawn, but there are no monsters or aliens and definitely no tentacles!

I think this is the reason why time travel doesn’t make sense.

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Fun fact, Back to the Future hides an extremely dark secret.

Because Back to the Future uses the non-self-consistent changes-the-past multiverse mechanic, when Marty returns to 1985 at the end of the movie, having clearly altered history so his parents are hip and Biff is a loser, he’s therefore in the new altered timeline. Since he’s from the original timeline, the new Marty who takes off in the DeLorean is not original Marty going back to close a loop, because original Marty departed from the original timeline. New Marty isn’t him earlier in his own timeline, he’s a new person from a different timeline (or universe if you like) that Marty either created or diverted himself into by changing the past.

So where is new Marty going? If he goes back to the same point in 1955 where original Marty crashes into the barn, new Marty will crash into the original Marty. Worse, Doc read the letter, so he would know this. Doc had the prudence to wear the vest at the behest of the letter, so he presumably also was careful not to enter the same date into the DeLorean. I see two options. Either Doc didn’t tell new Marty what would happen that night he’s shot, and simply entered some other date into the DeLorean for new Marty to go to instead of 1985 when he fled in a panic. Or he told new Marty what would happen, they duplicated events to fool the Libyan terrorists, and then new Marty voluntarily gave up his life in the new 1985 so original Marty could take his place. Either way, I hope new Marty went to some far future idyllic paradise and not, say, before the Earth formed.

There is one major inconsistency though. When original Marty begins to vanish because he accidentally stopped his parents from getting together, it shows that the original timeline disappears and he along with it. But when he changes it a second time, not “restoring” history but changing it to a timeline where the new version of him is born, the original version does not disappear along with the original timeline.

TL;DR - Time travel is homicide at best and possibly cosmoscide. Just say no!

Also the best time travel story is, IMHO, The Man Who Folded Himself.

It has some similarities to Heinlein’s earlier time travel stories, but is better written and more tightly plotted.

Another good time travel story is The Time Ships by Stephen Baxter, which basically just keeps pursuing the logical progression of events after The Time Machine by H. G. Wells, updated with modern quantum mechanics.


“I’ve been waiting for ages…”
“…needed a kick in the pants”

Dude. Go. Back. In. Time.

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It’s actually named after a Russian physicist…

However, other research in relativity suggests things are more complicated than that. It’s possible to demonstrate mathematically that a single outcome can be connected to a single cause by any of a multiple (and possibly infinite) number of different histories. What this means is that spacetime isn’t classically deterministic. Instead of thinking of it as a static thing, it’s more appropriate to think of it as a probabilistic equation. This doesn’t necessarily imply the multiple-worlds interpretation is correct. I personally am extremely skeptical of MWI and consider a flawed assumption based on the biases of the macroscopic human experience.

Basically, if there were a God, She really would place dice, Albert Einstein’s discomfort with quantum indeterminacy notwithstanding.

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