stop me if you've heard this one before the movie's hero is about to be sent back in time
to correct something in the past that's causing some urgent problem in the present but there's
any scientist friend warns them they must be absolutely certain not to change anything
except for the exact thing they're going back to thinks and under no circumstances can they
interact with their past self why not well of course that would create a temporal paradox
it seems like every time a story uses time travel we find it rapidly running up against these kind
of problems the whole thing rapidly becomes a nod of complicated interactions and causal
ripples across the fabric of the narrative and even when it doesn't cause narrative
ripples audiences are often quick to critique The Logical holes created by even the most benign time
travel scenario you almost have to wonder why anyone would bother writing about this at all
except honestly paradoxically turns out the paradoxes are actually just part of the fun
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thank you it can be pretty hard to find Opportunities to do really experimental
stuff as a content creator usually that kind of thing is pretty risky and can end up costing a
lot of money nevertheless we have managed to do some pretty weird stuff like this video about
a fantasy setting that basically has gigantic Geographic genitalia or this video about crafting
living beings with magic but the coolest thing we've ever done hands down our six part original
series worldsmiths which explores some of the most unique fiction by some of the most unique authors
junji ito's weirdly Pleasant psychological world of horror Neil gaiman's Darkly honest approach
to writing children's stories and a bunch of others we put so much effort into that series
and we are just so proud of it and the reason we got to do all of that this stuff that would just
be a bit too risky to try here on YouTube our streaming platform nebula we literally get paid
to do experiments over there so if you want to see us try more weird and interesting stuff visit
go.nebula.tv tailfoundry and sign up for just 250 a month there are a ton of other creators
experimenting over there too so once you're done with our stuff you'll have plenty left to explore
but definitely look at our stuff first again visit go.nebula.tv tailfoundry and go watch our original
series worldsmiths now back to the video you all knew there was no way we were going to talk
about this without bringing up Back to the Future right it was basically the movie that popularized
time travel stories and brought them into the mainstream way back in 1985 and that's kind of
funny because it's also overflowing with paradoxes in the movie our hero Marty McFly is accidentally
thrown 30 years into the past back to 1955 there while looking desperately for a way to get
um back to the future he accidentally gets between his young parents and prevents them from getting
together this is of course a problem because if his parents never got together that means
he would never have been born but then if he was never born how did he go back in time and
get between his parents and if he was never born and never got between his parents shouldn't his
parents still have gotten together and shouldn't he you know still exist this is probably the most
common of all the temporal paradoxes it's known as the grandfather Paradox because if you were
to go back in time and kill your own grandfather you would create the same essential Loop if he
doesn't exist you don't exist if you don't exist that would mean you also never killed him if you
never killed him you would still exist but it's not really that literally either it's not just a
thing that happens with murder this can happen in a lot of different ways say you go back in
time through a portal and then while you're in the past you prevent yourself from ever going through
that portal this too would be an example of the grandfather Paradox just sends the grandfather
another of my favorite twists from Back to the Future happens when Marty McFly is at a school
dance and he plays Chuck Berry's 1958 rock and roll hit Johnny B Goode which Chuck Berry himself
who is there on stage with Marty hears for the first time and goes on to steal and pass off
his Zone suggesting that that's where the song came from but back in the future the Chuck Berry
version was the one Marty originally heard if he learned it from Chuck Berry and Barry learned it
from him where did the song come from this is what we call the causality or the bootstrap Paradox
named after Robert heinlein's 1941 novel by his bootstraps which makes extensive use of it it's
basically where something from the future is also its own source in the past creating a complete
causal loop with no actual start point one of the underlying ideals here is that you can't change
the past because everything you do has already resulted in the future you've been experiencing
every change you try to make somehow brings you back to where you were in a weird way it's the
exact opposite of the grandfather Paradox instead of something preventing itself in the past this is
something causing itself in the past intentionally or no but that raises an interesting question if
Johnny B Goode was a song that already existed and existed because Marty went into the past and
introduced Chuck Berry to it doesn't the fact that it existed in the future demonstrate that
there was never actually any path but for Marty to go back and introduce him to it otherwise
how was the future ever possible if that's the case does Marty even have the option to cause
this Loop or is the fact that it exists already evidence that it was going to happen anyway this
is known as the Paradox of Free Will and basically suggests that anything you do to change the past
was actually already done your meddling is just the natural trajectory of things and always was
by playing Johnny Be Good at the school dance in a way Marty was just fulfilling his Destiny this
Dynamic gets pretty complicated when a character becomes aware of this fact and intentionally tries
to circumvent it if Marty had refused to play the song this time too bad we already know he's the
song source so narratively what ended up causing him to do it was it somehow an accident does he
realize that he needs to for some reason maybe to preserve the Integrity of space-time there
are a lot of interesting ways to play with this one especially in terms of how the characters
caught in the Paradox react to it so those are the three big ones the grandfather Paradox the
bootstrap Paradox and the Free Will Paradox I'm sure there are other variants or sub-variants out
there but these are the ones you're most likely to run across and in Back to the Future the tone
is relaxed and fun enough that you really don't have to care but for a more serious story these
can often be deal breakers for immersion if we were really invested in the question of
how Marty's trip back in time affected the future it might be frustrating for the final answer to
just be a nonsensical Loop that you're just not supposed to think about too hard in fact
the idea might even be so unpalatable that any of you writers watching might just be tempted
to avoid time travel altogether just so you don't get caught in The Logical spaghetti mess
of one of these paradoxes and I wouldn't blame you fortunately not all time travel stories have to be
like this in fact a lot of them are so airtight that they literally can't have paradoxes in the
game Zelda Majora's Mask the world of termina is going to end in exactly three days the Moon
is falling and nothing can stop it nothing except for a little magic our hero link is no stranger to
time travel and with his magic Ocarina he's able to learn a tune that will send him exactly three
days into the past to the day when he first arrived and realized the world was ending
you spend the game watching the clock tick down resetting over and over losing almost all your
items restarting from scratch searching for a way to avert the coming disaster you do however
get to keep your memories and any items keyed to the gims progression so Day by repetitious
day as the world repeats and you become more powerful more influential more knowledgeable
you're finally able to do enough to stop the moon itself from crashing down and At Last Link is free
from this three-day doomsday Purgatory this is our Classic Time Loop narrative extremely common but
not actually a paradox that's because it's an insulated bubble there's no ripple effect into
the future because until you choose the right path and find the solution to the problem time
simply won't progress and despite the riddlesome nature of having to find the right way out there's
also no free will Paradox here because you're not actually predestined to choose any given
path you could just stay in the bubble forever you could make link live out the same three days for
eternity or even just let the moon come falling down that's up to you the self-contained nature
of this Trope lends itself really well to trial and error stories and it's so uncomplicated you
actually kind of see it all over the place heck you could even interpret the save system in the
game as a miniature time Loop where when you fail you're sent back to an earlier game State
over and over until you do the right thing and break out of the loop there are also some time
travel stories that avoid paradoxes by splitting time up in the visual novel Steins Gate possibly
my favorite ever depiction of time travel a group of friends stumble across a way to send short text
messages into the past and then how to do the same for someone's Consciousness sending it back up to
three days in time into their past self's body any choice they make that differs from their original
timeline will Branch them off into a parallel version of reality with everyone's memories
save for the main characters changed to match it seems like a pretty sweet deal until you start
to confront all the horrific ramifications of meddling with time this way are they technically
killing themselves every time they overwrite their alternate self are some events so powerful
that they're just a destined to happen on every timeline no matter how you try to change them
there is tragedy here and complexity and headache Galore but no temporal paradoxes while there are
a few plot holes They Don't Really involve the time travel system itself which makes it a pretty
satisfying experience overall this type of time travel is often referred to as split timelines
or alternate timelines in these universes every potential change in a timeline causes the timeline
to Branch like a Choose Your Own Adventure book with different endings in a model like this
killing your grandfather spawns an alternate timeline in which you are never born but the
timeline where you were born and thus can go back and kill him still exists if you can find your way
back to it and then of course there's traveling forward through time one of the earliest time
travel stories The Time Machine by H.G Wells is actually just this the narrator travels into the
future and sees the tragic state of humanity as it evolves into what are essentially two
new species sees the environment changes the sun gets hotter sees the last living life forms on a
desolate near-death Earth and then finally returns home because he's traveling to the Future and not
the past there really isn't an opportunity for anything he does to have a causal effect on the
timeline so rather than paradoxes we end up with something a little closer to prescience where
he gets to see what events are to come the time traveler in H.G wells's story doesn't do anything
to change the future he saw but in theory he could try the result could be a little like Scrooge in A
Christmas Carol who gets to see the future which will result from his current path and choose a
different one so time travel stories don't really have to be paradoxical messes and if that's the
case why would any writer bother with the ones that are why not stay in the safe insulated bubble
of a Time Loop or the rationally excusable world of parallel timelines or the relative tidiness of
future time travel the answer won't shock you but it needs to be said it's because these paradoxes
are interesting and fun even with all of their logical failings remember earlier when I said
that link the hero of Majora's Mask is no stranger to time travel that's because he does loads of it
in the game's predecessor Zelda Ocarina of Time the game is pretty good about avoiding paradoxes
for the most part but weirdly one of my favorite moments when you travel into the future to learn
a song from someone who says that they learned it from some kid in the past and then you go back in
time and play it for them in the past becoming the kid that they originally learned it from both the
Free Will Paradox and the bootstrap Paradox are at play here and still it is so much fun at one
point in Harry Potter and the Prisoner of Azkaban Harry saves his past self from being killed by
Dementors an event which happens earlier in the story and during which Harry seeing his future
self in the distance mistakes himself for his father come to save him from Beyond the Grave
it's a touching awe-inspiring moment that has always stuck with me even though technically
the method they used for time travel is just Rife with problems it's a bobble called a Time Turner
which allows characters to travel a limited distance into the past Hermione's been using
it to study and cleverly the characters realize they can use it to fix some of the events that
happen near the story's end but is it clever though really as we've seen by Harry's use
of it to save himself anything you can use the time Turner to go back and change in the past
will already have resulted in your present so they really had no choice but to do this right
yes probably but the scene is still awesome you can get lost for decades in the terrible fridge
logic of Harry Potter's time travel and the time travel of so many other stories but if
you don't have to why would you this story about kids learning magic and turning into animals and
playing aerial death Sports the time travel brings something wonderful to the moment logical holes
and all just like we do with Back to the Future it's worth excusing so that we can enjoy it even
if it technically makes very little actual sense the Paradox of time travel paradoxes is that while
they make the story convoluted and brain meltingly hard to wrap your head around that very quality
also makes them fun just like the best magic as long as it doesn't harm the Integrity of the
rest of the story experience doesn't make Marty's Adventure any less comedic or enjoyable to watch
doesn't take anything from the emotional beats in Harry Potter it's okay if your time travel is a
little zany worth it even if it presents moments and opportunities you wouldn't otherwise have
found so let your character kill their grandfather let them be the source of their own Inspirations
let them meet Fate by trying to avoid it let there be Paradox as if the story wants them because in
the wonderful spaghetti mess that is time travel who knows what might happen next if you let it
speaking of possibilities this video was just a taste of all the interesting stuff we want to do
with video creation there are so many boundaries we haven't pushed yet that we are just aching to
unfortunately experiments can be pretty costly unlike regular content you really have no idea
how something experimental is going to perform and doing something new with content creation almost
always forces you to dig a little deeper into your wallet nevertheless we have managed to do some
pretty weird stuff over the last few years like this video about a fantasy setting that basically
has gigantic Geographic genitalia or this video about crafting living beings with magic but the
coolest thing we've ever done hands down our six part original series worldsmiths which explores
some of the most unique fiction by some of the most unique authors jinji toh's weirdly Pleasant
psychological world of horror Neil gaiman's Darkly honest approach to writing children's stories and
a bunch of others we put so much effort into that series and we are just so proud of it and
the reason we got to do all of that this stuff that would just be a bit too risky to try here
on YouTube well we actually have a completely different streaming platform for it called
nebula it's amazing we literally get paid to do experiments over there all of our videos upload
on nebula a whole week before they upload here on YouTube without any ads and like I said all the
weird stuff that were just not able to risk making for YouTube goes up there too in fact it's the
only place you can see a lot of it and we're not the only ones who have been posting there the the
same is true for so many other amazing creators the entire platform was built by creators for
creators every time you watch a video over there a Creator you love is getting paid and far more
than they would ever get paid on YouTube for a lot of us over there it's become the single best way
to fund our more experimental ambitious content like our original series worldsmiths and here's
the really fun part you can get nebula for cheaper than almost any other streaming platform on the
internet like 250 per month that cheap we want you to have access to our nebula content so we've
managed to get hail Foundry fans who sign up using our link a whole 40 off the usual rate all you
have to do is click the link in the description or go to go.nebula.tv tailboundary and sign up
for one year that's it and with our discount on that first year the whole year is only going to
be thirty dollars which again comes out to just 250 per month frankly I'm not quite sure how they
can afford to do this for us but I'm definitely not complaining seriously take advantage of this
offer while it's still going I don't think a better one exists in the world of streaming
anyway that's all for this one thanks for watching and
keep making stuff up I'll see you next week bye
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