back to the future paradox explained

[DJRyan8]

The reason Marty and Doc didn't go out of existence is because Biff getting the book did not affect Marty and Doc's births.

[keyzcity]

This is what happened to my life.

[MikeAM78]

The BTTF movies are probably the easiest movies to understand in regards to their use of time travel. Many make it confusing. But if you just pay attention like a normal movie-viewing person, you should have no trouble understanding it all.

[vicko620]

What?

[awsingleton07]

Somewhat wrong. Once old biff handed himself the book the future changed. a DELETED scene shows old biff getting erased. we see that when he comes back he is in pain. marty and doc are no where in particular for them to realize the world had changed or if they did themselves. It could have (most likely did) change instantaneously around them and then they went back to the past which was now the alternate 1985. they cant be erased because they are the 1985 doc and marty. alternate reality or not

[THEDARKMINK]

DID you know that was an escene omitted in the movie when Marty in the alternate future is entering the building where his mother and Biff live and he meets with alternate MARTY ?? that would be awesome

[emabardo]

that's really nice

[RtrTravisTWIG]

The picture should not fade when Marty stops George and Lorraine from meeting. a picture is still a picture.

Im pretty sure if i went on Facebook and took a picture of someone's post, then they delete it, i should still see the picture.

[Rabite890]

@RtrTravisTWIG Even if it was never made in the first place? They never met and had Marty or the other two. So the picture didn't happen. Time is "fixing" things to the new reality. If it doesn't belong it's going to be removed.

[AkabaneKuroudo]

"Obviously, somewhere in the past the timeline SKEWED down into this tangent[draws new line and writes 1985A] creating an alternate 1985." LOL xD!!!

[baigui]

Okay, serious.

As for the Paradox, proper reasoning, but sadly it was based on faulty premises.

Most paradoxes are crack-able or simply don't exist.

It exist due to the incapability of language to convey certain thoughts. e.g '' Im a liar'' OR Philosophers coupled faulty premises with PROPER reasoning and fooled people thinking it was a paradox.

[baigui]

Actual explanation for the paradox.

1. Time travel dont exist.

2. Its a movie.

conclusion : vexing over this paradox is like feeling sad for not being able to kiss snow white or cinderalla or both.

[xLexC7x]

Biff was able to bring back the delorean because in the end, the future wasn't going to be changed by what he did beacause Marty fixes it in the end.

[screenON14]

Why do you display the text like that? takes so much time, it's boring...

[trulymeparker]

So Biff got the Sports Almanac, went to 1955 and gave it to his younger self then returned to 2015 and he fades away because he got knocked out by the door of the Delorean which probably killed him in the alternate 1985

[BoyKagome]

Now this fading prowess would effect Marty last because he would be the deciding factor that has the chance to change the future. Marty is what makes the future unsure thus has a form of resistance to the flow. George hesitation to save Loranne at the dance is where time believes the two wont get together and thus starts to erase Marty. One might conclude that Marty's suffering somehow triggered George to act on a kind of parental instinct and take Loranne back.

[BoyKagome]

I'm not so sure its a paradox to say they should fade. My real question is how Biff brought the time machine back, he went back in time and gave the book to himself thus creating the alternate 1985. So if he went into the future from THAT reality he'd be in alternative 1985 too. The Time Lag I always thought of as "history unsure" As in it doesn't believe that at the current rate that a certan event will happen and as it makes its decision, people fade.

[TheRealTray]

Ypu are all forgetting the most important info! Bttf the game!!!!!!

[shoaibchh]

well u cleareed a lot of things for me.....m a big fan of bttf

[bhensley80]

You can argue that point but I still believe it to be a movie so I can think whatever I want.

[bhensley80]

So if you want another answer the knowledge was with Doc the whole time so all that would have to happen is Marty get to doc explain all that has happened and what he created then just by knowing it is possible the time machine will be in existence even if in an alternate future,It has to be in an alternate,just because of infinite possibilities.So doc thinks it and brings it to this time knowing it's needed now and builds it latter in the alternate fixing the paradox.

[bhensley80]

I have read a lot of the idea's of the movie paradox and came to one conclusion!You are overlooking the facts,the fact are this is a movie and in the world of the movie you have to do what make the movie go forward into the future.If you argue a paradox the movie can't go on.So just enjoy the show.Problem solved.

[Xlivesforever]

if he did and didnt at the same time its a paradox

[Xlivesforever]

ok im glad someone else notised this cause ive been looking at this for years

you missed something though

martys father was killed AFTER marty was born but the whole thing wouldnt of happend anyway cause when biff changed the past doc would of ended up in the nut house and have never had the chance to invent the time machine in the first place meaning that biff could of never changed the past in the first place cause there was no time machine to being with so he did and didnt at the same time

[8833darren]

biff didnt usethe sports book until he was 21 so old biff could go back to the future as no bets had been placed time only changed when biff won the money

[bayanna1996]

k this dosent have to do with this vid BUT marty mcfly is th best trouble maker and cool kid ever he apperantly got in trouble at school alot but he went to the past where he became a trouble maker befor he was born and the cause of that made his parents not love each other but he changed it and the were dressed in suits his mom liked the idea of marty with his GF i cant remember her name so marty should remember her like that which probably would of changed something else like when he went back

[bayanna1996]

@bayanna1996 i posted the previous comment but ran out of characters when he went backso it was exactly the same right something must of changed

[hailstorm9280]

you know when future 2015 biff got out of thedeloreon he felt pain thats because he was fading from existence cause during some point between 1985 and 2015 biff got shot by hiswife lorraine is what the trilogy said

[mspeter97]

@hailstorm9280 how did ya know that!

I though the old biff was fading away because he changed his past life and became a rich old man!

[jackchrisevans]

@hailstorm9280 there's a deleted scene from the 2nd film where old biff lies on the floor and slowly fades and disappears, but the creators thought that people wouldnt understand what was happening

[kansaspacific]

In this alternate 1985 does Huey Lewis still have a hit album? Or will the soundtrack be written by Poison?

[andraken]

It is strange that however Marty already changed the timeline once when he come back in 1985 after he helped his father, and everything is alright despite that is a new 1985

[SpreadLoveMovies]

if u didnt understand that when u watched the movie then u didnt understand the whole movie i guess.. nothing new but well explained

[0706823245]

time travel never makes sense if you think about it too much.

[chevymang72]

What would happen to the dog if hadn't shitted inside the Delorean?

[canadianbacon007]

Who is the third who walks always beside you? When I count, there are only you and I together DA Datta: what have we given? My friend, blood shaking my heart The awful daring of a moment's surrender Which an age of prudence can never retract By this, and this only, we have existed Which is not to be found in our obituaries Or in memories draped by the beneficent spider Or under seals broken by the lean solicitor In our empty rooms DA

[defaultuser404]

If the Doc's explanation is true, than Biff would have returned the DeLorean to an alternate 2015. But Biff returned the DeLorean to his continuum of origin, so this event contradicts the Doc's explanation. Regardless, like others have said, it's just a movie. I suppose we just have to suspend disbelief.

[mephlies100]

@defaultuser404 yeah and when old biff gets back he starts to feel the same pain marty did when he was fading out of existence

[jOWNZin22]

Back to the future is actually the bible...yet many people do not even realize....resulting in the world we live today instead of the world God created.

Do you think back to the future was just pulled out of someones ass.

[NDIrishfan93]

Marty would be in Switzerland that SON OF A B**CH!

[MrAu009]

its funny how everyone here thinks they're time traveling experts just by watching back to the future...chill guys its just a movie

[Pauluk33]

If you go back and time and change events it called the grandfather paradox

[Firecont]

the point is that the paradox results when you try to change somthing from the past by doing it your younger self will have no intentions to go back to the past to do the samething so lets say that you are a kid and brake a window but youre lucky to have a time machine you go bake to the past and prevent you fom breaking the window so if you did not break it you did not go to the past but you are in the past becuse you travelled to prevent yourself from breaking the window.

PARADOX :l

[TheRapidFire94]

Give me some thumbs if your brain is fucked.

[donniedarkodevotte]

Shouldn't they (Marty and his siblings) be wearing different clothing in the picture? Since the timeline changed (George McFly becoming successful as well as Marty's brother) they should be wearing different clothing. The older brother, for sure.

[Jake9360]

If George died before marrying Lorraine, then Marty won;t be born at all, and there will be trouble. She will marry Biff instead.

[Weasleville]

@Jake9360 If the doc is institutionalized, then he won't build the time machine and marty would never go back in time to 1955, come back to 1985, the doc would be killed by the libyans and they wouldn't go to the future to save martys kids and biff wouldn't have the chance to go back to 1955 in the time machine and biff wouldn't build his fortune, kill george and create the alternate time line and have the doc institiutionlized :(

[cyberpsygen7]

@Weasleville its called a saw tooth snap, which can resolve into cycling causalities in an infinite loop or not. mark joseph young goes into super details about time travel theory on his site and has been debating it for years there, refining everyone's understanding of temporal theory. google for it, you'll find it easy.

[MrShadowxtreme]

justin beiber is a time paradox... he supose to never born

[dim432]

but marty said will go back to the future and changethings.

"you cant because if you do you will still be in 1985 this will be the future"

the only way to stop this, is to go back to the past and repair that damage.

[arturocas90]

What I don't understand is...how come in the alternate 1985 Biff expresses Marty should be in a boarding school in Switzerland or something...that means there's two Marty's or the one from the Alternate 1985 is replaced with the one who got back from 2015?

[druvirus]

@arturocas90 There would be two. The one who grew up in the alternate 1985 and the one who time traveled.

[CharlesSteele08]

The truth about Biff is that he went back to 1955 to give the Almanac to himself as a young man And when he got back to 2015, he got out of the Delorean and went behind that one car as you saw in the movie and disspears from existence because at some point between 1985 and 2015, Lorraine shot Biff because she was tired of him abusing her and being mean to her. So go and watch a deleted scene of BTTF part 2 and you will see what I am talking about.

[JTS1128]

Oh but about Marty saving his father from getting hit by the car

The movie kinda protects against it by using the Dance and The Kiss as the true means of Marty's and his siblings existence

[JTS1128]

Yeah you are right about that that's the funny part about the entire time travel thing

It fails many times over

Marty going back and saving his father from the car technically wipes out his existence because that's how he came to exist, anything else would be different

Different wedding date, different kids, etc

And Doc going back to 1985 telling them about and taking them to 2015 instantly changes all the bad things that happen

[JTS1128]

Love the movie

One of the all time faves

I think the time travel theories fail because they're using Two at once

On one hand the future is there waiting to be traveled to hence the fact that it can traveled to like the did in 1985A at the end of the first movie

But then on the other hand, they say the future isn't written so when they traveled at the end of the first movie, they should've disappeared in the reality and their existence would've been in the time machine wherever they decide

[turmoil23]

@JTS1128 right, the 3rd thing you are missing is that, they also take for granted that they return. So traveling to 2015 and your future persona beign there means you returned, but as you are currently changed the timeline. They are in the future hence they havent returned to 1985 yet, but their 2015 persona exists anyway.

[arrayeniqma]

for me...when their back from 2015...doc n marty just trapped in time glitch...

ahaha...

wow this is cool clean debate...keep it up guys

[SMANCAT1]

u post a very interesting theory but i believe differently. it is very simple. When time travel takes place a 'ripple' effect occurs. it causes completely unexpected changes in fabric of time creating seams that u could slip through. Of course nothing could prove either of our theories correct but its nice to throw something new out there. :)

[kasdata]

Actually, Old Biff would not have been able to return to the future. The moment he handed the book to young biff, the future changed. If he went back to the future, he would have confronted himself (old and rich) in the new future. Just like Marty and Doc can confront themselves when they go to the future. Basically, as soon as Biff left with the Delorean, the future world Doc and Marty were in would have changed right before their eyes, and they probably would fade out of existence.

[quaternio]

@kasdata Exactly. Best case scenario: our Marty and Doc would have been stranded in the original 2015 until Doc was able to build a new time machine (which wouldn't have been hard, presumably).

[doc080]

@kasdata This is somewhat correct. The moment Old Biff left to give young Biff the Almanac he would not be able to return to the Reality from which he left. The logic of the movie suggests that reality would switch around the charachters. I contend that alternate realities and dimensions would be created and continue on playing out. Doc would have to invent a dimensionsal travel machine like that tv show Sliders. Otherwise, they would all be lost in alternate realities.

[mquiroz90]

@doc080 u saying him and docs universe has turn to a parallel universe 

[Jason34567]

so we can maybe say that instead of a time traveling machine , doc invented a dimension/reality venturing machine...

[DRMMRI14]

See, the thing is, that if you think about this stuff too much it doesn't make sense.

[blanbproductionshd]

@DRMMRI14 ya konw your rite. if you just go with it it actualy seems to make sence. but once you think about it it becomes jumbled

[TKnHappyNess]

Doc and Marty do exist in 1985A. Doc was committed, while we never see Marty.

[ShokaLion]

@TKnHappyNess He's supposed to be in Switzerland

[EMG81JSX]

Also, in part 1....If Marty meets his parents as teens, how in the world is their family life going to be the same in the future? What happened, they totally forgot that the kid who introduced them as teens just happens to grow up and look EXACTLY like him??? Wouldn't Biff have realized that teenage Marty looked like the same Calvin Klein person??? I mean, you can't write that off for a second.

[aldsish]

@EMG81JSX doc had intentions of brining them back to 1985 later on, so when they did that means they will grow up and be in2015 because later in 1985 they wouldve been there, and you can forget what people look like in 30 years

[aldsish]

@aldsish either that or they noticed the resemblance before and said something about it then

[EMG81JSX]

The one thing I could never understand is that, how can Marty and Jen go into the future from 1985 in part 2, and still see their future life? If the future is not written, wouldn't they just have been considered missing in 2015 and not married and together??? Correct me if I am wrong on that one.

[VAJT15]

@EMG81JSX According to what doc explains in the third part, the future isn't written. They were planning to return to their present, so if they would hold to the photo of Marty's and Jen's marriage, they could maybe (but probably not :D) see it erasing itself very slowly, every time they did something that put them into danger and that it could effect their lives or health. But cuz nobody dies, nothing changes until they return. But they probably have a limit when to return before they fade.

[turmoil23]

@VAJT15 problem is, every time the traveler moves forward he dissapears from "present" existance and goes to a future where he appears for the 1st time. For the traveler his existance is always present. "future isnt written" is just the message of the film.

[StalacticPro]

please stop the zoom!!!

[imnotevenme]

What Doc was saying is that both realities co-exist, not that alternate 1885 replaces old 1885, otherwise he would have erased the other piece of line, right?.

They went to the alternate 1885 reality because the old 2015 biff who ultimately created the alternate reality was from the same reality line they were in at the time. The other piece of line the was a reality of possiblity, - most possibly the reality of Marty and Doc never leaving to 2015, and never having to fix Marty's family life.

[imnotevenme]

@imnotevenme for all the people that still don't understand.... the last part in the video where it says "time-continuum is canalized into a single pathway" is that piece of line I was talking about, - it's "canalized"/confirmed when the almanac is retrieved by Marty at the end of BTTF II, (you know when Biff rams into manure for the second time :D), so then they go back to their designated timeline, - because the alternate 1885 timeline already had a Doc and Marty in it. :) lighten up people.

[imnotevenme]

@imnotevenme there's already a Marty and Doc in the alternate 1885, (remember Doc gets sent to an Asylum, and Marty was supposed to be in College). The point of the movie is explained here through the scenes but Doc makes it clearer at the end, millions of realities co-exist depending on everything we do now, the future is what we make it, make sure you pick the reality that co-exists as the greater one, make sure you don't pick alternate 1885, but even then there's a way to get out of it.

[Nicksolo85]

You asked why didn't Doc and Marty cease to exist?

Maybe since they weren't in their designated time period (1985 in this case) at the time the changes occurred, they weren't affected.

Remember when Marty returned to 1985 and he didn't remember any of the changes?

The 2nd Marty (I'll call him Marty B) that we see being chased by the Libyans grew up in the slightly altered timeline.

You could refer to the FAQ sections for all 3 movies on IMDB. They can explain it better than I can.

[pjamese3]

Or you coud use an old Doctor Who standby and say that since Doc and Marty are time travellers, their bodies are imbued with "time particles" and can resist changes to the timeline...allowing them to stil be in existence when old Biff flies the Deloren back to 2015, blah, blah, blah. Makes as much sense as the universe(s) caring about specific actions by people.

Or it could just be a plot hole by writers not well-versed in time travel theory.

[ermayo93]

Go back to 1955, blow young Biffs brains out and case closed!!!!!!!!!

[ACE0HUNTER]

@ermayo93

But then George wouldn't have punched Biff, thereby winning the girl and Marty wouldn't have been born - case re-opened :P

[ermayo93]

@ACE0HUNTER

Countless scenarios emerge. George punching Biff is one. Fate has a way of finding others somehow. George may have found another way with the influence of Marty in 1955. Marty stuck his finger in the socket in 1955 and altered the current of time-flow to one possible future.

[ACE0HUNTER]

@ermayo93

But that would depend on the belief in fate, as it is, that timeline was dependant on Biff being punched by George for Marty to be born and there was seemingly no other way for George and Lorraine to get together.

[Jake9360]

Old Biff had returned to 2015 from 1955 and he got out of the car with pain! So after he gave the book to young Biff, he started feeling painful, so I think Lorraine killed Biff sometime between 1973 and 2015.

[VAJT15]

@Jake9360 Yes, she did. Biff could go to any time and he would dissapear. But if he dies before 2015 he can't take the almanac to past self. And if he doesn't, he doesn't get rich so Lorraine doesn't kill him and he is alive and well in 2015 again. And now he can go back to give almanac to his younger self. It's even worse paradox than if he gives almanac to himself and he becomes rich. Because than he must be rich in 2015 too, so he won't get an idea to take an almanac to his younger self.

[ileerose]

In back to the future part 1 the only reason

the family start fading on the photograph

is because Marty bumps into his parents and Marty's mum falls for

him instead of George. That is why we see the photo fading.

Now to explain the part 2 laps.

If you had watched the whole film

Biff explains when Marty bursts into the Casino

"What's the matter did you get kicked out of another boarding school"

So in that alternate future Marty was still in a boarding school

[ileerose]

@ileerose Now as for Doc Brown well he got committed.

the reason why these two have not faded is because they have

not messed up the time line.. By bumping into their parents.

[adriebm]

i can't figure out why the timeline didn't changed to the old Biff when he returns to 2015 after handed the book to itself.

[bigglou]

@adriebm When he returned to the future you notice how he was in bad shape. On the commentary, it was mention that Marty's mom shot Biff in 1996. On the deleted scene, he was being erased.

[adriebm]

@bigglou Man thx

This is mind blowing

i saw the deleted scene you said.

BTTF is my favourite movie.

[bigglou]

@adriebm No problem glad to help out a follow BTTF fan. FYI its coming out on Blu Ray 10/26/10 date seems fimilar doesn't it.

[pjamese3]

@adriebm  Unfortunately, the movie makes use of multiple time theories. It's a mess that way. Most of the first movie is alternate timeline, but the sequel combines alternate with single timeline theory. Rich Biff's world should have taken over in the future. No time traveling Doc and Marty in his world. They'd still be looking for the Delorean in the previous timeline.

Later, back in '55, they use the single timeline theory (Marty keeping the gang from jumping him as he's playing guitar.)

[Atothepowerof3]

the future is written, we just play the roles or elese when we travel into the future, nothing will be their. We aready made all of our futures becasue of our personality that would casue us to do things. we just play the role in our lives.

[maximusmop]

i agree that in bttf2 a time lag/paradox is created, so marty and doc would have until biff's first use of the sports almanac to sort the 1985a correct, that is when the timeline would skew into the tangent?

[thoughtsurfer1]

If you recall, they used that time-lag thing in THE SOUND OF THUNDER, also. The disrupted future came upon the world in waves, which conveniently matched the plot.

[CrazyJustin2006]

something that I saw on another movie site for you guys to check out. In that scene at the end of Part 3 if you look closely at one of Doc's boys one is motioning to someone off screen that he has to go to the bathroom.

[InYourFaceNewYorker]

How do you know that he's doing that and not just absent-mindedly playing with his hands?

[CrazyJustin2006]

because he points to someone and then points to his thing....

[xXexecutiveXx]

Also in part 1...after George knocks out Biff and marty returns to 1985 to see how everything is different that itself created an alternate 1985 and noone says anything about that.

[trlkly]

Mostly because, unlike the other change, it turned out better. The only reason they changed 1985A back was because it was obviously worse.

[xXexecutiveXx]

The biggest paradox i saw was in Part 2 when Doc returns and says Marty and Jennifer something has to be done about your kids. He takes them to 2015, way past that lag time, so when they arrive in 2015 marty and Jennifer should be missing for 30 yrs since they left in 1985.

[trlkly]

The time lag must take place relative to the time traveler. In other words, the entire future where Marty and Jennifer were not lost would have faded out of existence in a week, just like Marty did.

Fanwankery, Ain't it grand?!

[xXexecutiveXx]

The Continuem lag is exactly what the producers of the show said. That is why after Biff gave the book to himself in 1955 he was able to return the time machine to 2015 before the alternate time line took place.

[scottieman2]

Like all time travel stories, it isn't suppossed to be thought out to extents. I tought it about it and all but don't take it to deeply. Just a movie.

[thelyniezian]

It would however have been a lot simpler if the makers of the film had stuck to many-worlds theory- since marty's disappearance could have brought about a graandfathe paradox in which he couldn't have gone back to change events. And it soles this whole delayedpchange thing which seems to make no sense physically.

[scottieman2]

thelyniezian, kinda like Sliders.

[thelyniezian]

Something like that, yes.

[barkboingfloom]

What will happen to revisied 1985 Marty (the one who leaves Lone Pine Mall) when he gets to '55? His parents were upper-middle class and raised their 2 older children differently than our Hero Marty recalls. Lone Pine Marty is a different person. Will he still follow his dad around? What if the car hits George like its supposed to and Lone Pine Marty returns to Hero Marty's 85 where his parents are lower middle class dorks. Wouldn't that seem almost as scary to him as the "Hell Valley" 85?

[mephlies100]

@barkboingfloom no because they marty was already there in 1985B so either way things will still be the same

[shadowstalker1120]

It's the same principle as the paradox in terminator.

[chrisacc82]

how bout this one: remember in BTTF 1 the letter that Marty had to write doc in order to keep him from getting shot? At the end of BTTF 2, 1955 Doc passes out when encountering Marty again, so he wouldn't be able to tape the ripped letter back together. And Marty does nothing this time to make sure Doc reads or ever gets the letter. So how then does 1985 Doc ever get the letter and come prepared with the bulletproof vest? 1985 Doc would have faded out of existence after traveling to 1885.

[SP13TV]

And at the end of the third movie when doc doesnt stay in the future wouldnt that mean that the delorean time machine never existed

[DoctorEmmettLBrown]

Says who?

[DoctorEmmettLBrown]

Remember, he has a whole 30 years to read that letter.

[SP13TV]

in bttf 1 its hard to notice but after the lightning knocks the tree down doc puts the note in his pocket

[scottieman2]

remember chrisacc82, Doc put it in his pocket, he probably read the letter sometime after Marty left.

[DoctorEmmettLBrown]

...

WRONG.

Doc and Marty didn't erase in 1985A because they're from a DIFFERENT TIMELINE.

[pdennis93]

actually they would have still existed. Marty's dad didn't die until 1973 which was after Marty was born, and doc was still alive. so yes they would have existed in 1985A

[VampireYoshi]

@pdennis93 But their personalities -would- have begun changing, likely mathematically relative to their chronological distance from the two temporal event junction points. In part one, point one to point two was but a week's time, 5 November to 12 November 1955. In part two, Biff doesn't start making his millions-into-billions until his 21st birthday, in 1958, and the psychological and/or horrific changes that impact his family likely don't really start setting in until George's death in 1973.

[MetallicEnergy]

@pdennis93 Actually, the ORIGINAL Marty and Doc would have not existed. The New Marty and Doc should have replaced them.

But, It's a Movie, and it's one hell of an awesome one!

[russell19831983]

in the altered 2015 Biff is dead so he CAN NOT go back in time to give his younger self the almanac, how about that for a paradox

[ioncloud2012]

@russell19831983

In the altered 2015 Biff DOES NOT have to go back in time to give his younger self the almanac, because he already did that in the original timeline. .

There's no paradox here.

[maximusmop]

@russell19831983

i agree that in bttf2 a time lag/paradox is created, so marty and doc would have until biff's first use of the sports almanac to sort the 1985a correct, that is when the timeline would skew into the tangent,and as for biff being already dead in 2015 he would not have changed history till his return to 2015, thus why he wandered off in agony and in the deleted scence as the delorian take's off he dissapears.

[pjamese3]

@maximusmop No, old Biff changed history as soon as he landed in '55. Every action by young Biff changed it even more. Old Biff just bypassed 30 years when he returned. Even under single timeline theory, Doc and Marty should not have still been there. It's because the writers didn't really understand time travel theory. Like the pictures and headline changing with each action. Those are artifacts of the previous timeline. They shouldn't change. They're just devices for the audience.

[tiagomegas]

@pjamese3 thank GOD for that :D Its a comedy, not a documentary xD

[turmoil23]

@tiagomegas its the problem with time travel themes, writes feel that they have to explain a bit of how their time travel works, and thats when it falls to pieces. Having a scientist in the movie that cares to explain a few things based on actual theory, hurts it a bit.

[Jake9360]

@russell19831983 It would be too late for Old Biff to stop his other self. He is dead.

[DaveFrehley]

At 4:41 the kid (or perverted dwarf) who plays Doc's son Verne waves for the camera to come closer & he points at his junk. lol

[b0w5er]

:O WOW I never noticed! we should sue them!

[VAJT15]

I think that, if the Marty would disappear and if his parent wouldn't kissed, our galaxy (or universe) with be destroyed. Because Lorraine was in love with Marty and if he would disappear Lorraine would miss him (if she would't kiss George and fall in love with him). So, if she wouldn't be in love with George, they (probably) wouldn't have and children. So, Marty wouldn't exist either. But if he wouldn't exist, who would be the one that make this happen? I think that that is also a paradox.

[VAJT15]

If the old Biff gives the almanac to the younger self, and later he becomes rich, that means that he is also rich in future / his present = 2015). So, if he is rich when he returnes to 2015, he would never think about that he can take the almanac to younger self. And he even couldn't take the almanac to the younger self, because he would't be able to steal the Dolorean. Because doc is commited in alternate 1985. So he and Marty would't be travelling into the future.

That is paradox, isn't it?

[bumcheeks101]

@VAJT15 that is why time travel is so dangerous lol

[spotturo]

@VAJT15 so old biff gave the almanac to young biff so when old biff goes back to 2015 he will be rich?

[kasdata]

@spotturo I think the tricky part is that if Old Biff goes back to 2015, he will meet himself (young Biff who was given the almanac now 60 years older) So 'he' isnt the rich one, his other self is.

[VAJT15]

@spotturo Except if he dies, like in the deleted scene. That would almost explain how Marty and doc can still be in 2015, cuz Biff richness didn't effect them so much that they don't time travel. But if he changed most of a city before 1985, it probably still wouldn't be the same in 2015 like it would be if Biff wouldn't changed the past. But Marty was probably send to Switzerland and doc was probably commited before 1985. So they couldn't time travel to 2015, where Biff steals the Delorean. :S

[turmoil23]

@VAJT15 actually when he returned to the future from 1955 he would never return to the original 2015. Meaning marty and the doc would never have the time machine in the future, thats a big hole in the movie´s story.

Continium Lag is just the excuse to explain why changes are not instant.

If the posibility of time travel is real, when something is changed the original timeline would just fade of existance. All this considering everything is glued to the time continium.

[turmoil23]

Just the existance of a foreign object even as an observer is a consecuence of a new timelime where that object existed, timelines would be the same but different for that event.

Its all theory and it seems that time travel is impossible for mortal beigns or at least for the level of conciuosness/awarness that mortal beigns have.

[druvirus]

@VAJT15 Time Travelers Immunity, a concept coming from Chrono Trigger fandom, would come into play in this scenario. An exert describing it states ".. that once an entity travels through time, he or she is disconnected from the original timeline by changing history (past or future), and causality and consequences are resultingly broken." It's a possible explanation. Plus, multiple-worlds theory would also come into play here, allowing for divergent universes as well as time lines.

[wwazman]

Holy crap that intro text is ANNOYING!!

[WolYou]

Time isn't a line. It's a block. If one starts to think as time being a line he'll end up with a paradox. Spacetime of the past is a picture in our heads. The future is a projection. Both aren't real. If you're travelling in time you are travelling to imaginary places. When we are talking about "time", we are actually handling symbols, not realities. I.e. Numbers: You'll never see one of them walking around. But we are dealing with them daily. Reality and symbols are two diff. things.

[b0w5er]

its an analergy, its supposed to help mortals understand it.

[kaiyuss]

lol

[ec100]

In Back to the Future 2, isn't it impossible for Marty, Doc, and Jennifer to see themselves into the future, because the 1985 trio went into the future and they were in the Delorean the whole time, so how could they have been developing on the ground. In other words, they were in the Delorean the whole time while traveling into the future, or dilating time.

[jacobg500]

that then simply proves that they returned back to 1985 and developed from there.

[weirdstuffanimation6]

the massive problem with that the future not been writen yet in theiory dosnt that make time travel to the future im possible as it dosnt exsist or if it did exsist that would mean your life is on a set corse meaning every thing you do is not your free will

[Thebassistguy]

In BTTF 3, Doc mentions that "This photograph represents what could happen if the events of today continue their course into tomorrow." Basically saying, this is the MOST LIKELY future, but nothing is written in stone.

[weirdstuffanimation6]

ahhh ok then i must have missed that thanks

[EzumiKhan]

wow. very educational.

[Leohuizar]

Another paradox question: In Futurama, 'FRY' goes back in time with his friends, unintentionally killed his granfather, and unknowingly inpregoed his grandmother. Yes, Im serious. If the Alternate timeline thing is in effect, wouldnt he just be a making new inbred generation infinitely [like a spiral of inbreeding through time]everytime the regular timeline passes upthrough his birth and future, then time travel to the past again to kill grandad and prego grandma? [oh dear god my brain hurtz]

[Leohuizar]

Ive played Timeplitters Future Perfect on PS2 [FPS X timetravel X awesome game]and there is this scene where the "hero" Cortez, gets a key to unlock a door that he has to use to progress, but above him through some bars in the cieling, 'Future cortez' [after passing through a wormhole] tosses 'present cortez' the key to progress, and then 'Present cortez' will repeat the cycle later on. Where did he get the Key? I couldnt find it anywhere i just got it from the future? HOW?!

[brom5]

Then according to this time lag theory, which I guess makes sense, shouldn't the future Marty have been slowly disappearing from existence the minute current Marty arrived in 2015? Because technically future Marty couldn't exist. And how can they co into the future at all if according to Doc Brown the future isn't written yet?

[trailersic]

Are but iwas still written that 1985 marty would be returning back to 1985 to become future marty, nothing was in the way of that until biff took the book back.

[FuturamaFreak3000]

ah yes, in part II when biff said that marty was supposed to be in switzerland, i had wondered, "how would marty have been able to go back in time in the first place if he had been in switzerland?, and would doc have even built the time machine in 1985A to begin with?" well now i know. :) (still i had a hunch that the space-time continum gives you time to correct a paradox before its too late rather than just immediately imploding on itself or w/e)

[InYourFaceNewYorker]

Some people think that the alternate time line is a parallel universe and that there are two Martys and two Docs there. Of course, this doesn't make sense given that when Marty changed 1985 in the first BTTF, he simply changed the time line and didn't end up in another universe. It really isn't clear in Part II.

[andylythe]

that was the most annoying video I have ever seen, it would have been great had it not been for the never ending, head ache causing pop up short sentances, I had to turn off half way through. Change that and this would be a great watch.

[FiendlyDevil]

I agree with you on that, but if you do sit it out and watch it to the end-- it's pretty informative nonetheless. The multitudinous baby-bite-sized sentences were still annoying though. Despite that, I think we can all agree that Back To The Future kicks ass!

[ejayhrida]

Well done mate, well done. ejayhrida.

[todosprecatoejerri]

non ci ho capito molto a dir il vero:))

[EnterpriseKnight]

Succede quando si parla del viaggio nel tempo.

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