VSauce! I'm Jake, and after watching the movie Arrival I started thinking about time. But not linear time which is what we generally experience, different concepts of time. So I decided to talk to an expert on the topic, Neil deGrasse Tyson, on variations of time. TYSON: Before relativity, our concept of time was that we are all participating in the same ticks of the clock: one second for you is one second for me - that's linear time. Linear means every interval is the same as every other interval and one follows the next. Relativity, we learned that there is no such thing as absolute time. Time is relative, so time can be stretched, for me relative to you. So, time has multiple, sort of, parallel rates at which it flows, depending on the state of who's making the measurement and the state of who's in motion, and what conditions they are in. Now think of time as a dimension. TYSON: In our timeline we are prisoners of the present, forever transitioning through our past into our future, so we don't know of access to other points in our own timeline. Suppose you could move around in your timeline with the same flexibility as moving left and right, up and down, forward and backward. If that's the case you can revisit your own timeline. Under those conditions you do not die. You are always dying. You are not born. You're always being born. That's another kind of interesting way to think about time. So what we don't know, and this is a topic touched on in the movie Arrival, if you rejoin your life at a different point on the timeline you have to ask, do you have the benefit of the knowledge acquired after that? JAKE: You can go from the future to the past and maybe you'll have all the knowledge of everything because you've experienced it all but if you go from the present to the future would you experience everything that you would have, had you stayed in that timeline? TYSON: That's a good question, because if your timeline is already existing then you cannot change your fate. It's already writ. But suppose you had knowledge, and could change it, then you would have this sort of pair off a whole other timeline and it will become a very complex, sort of, fractal structure. TYSON: So, what gets me about Terminator is he's got to kill everybody who might be the mother of the future of the person who overthrows the thing. JAKE: That is always a thing, I thought, why don't they go further back in time? TYSON: You can go further back just have one little thing change and everything after that would change. Then it just wouldn't be as bloody. JAKE: Yeah, it wouldn't be as fun. (Laughter) But that actually brings up an interesting concept that I think about a lot... I think about a lot when it comes to the Terminator which is the Bootstrap Paradox where them going back in time is what starts the events happening in the first place. TYSON: Yes, so what happens is... So Jim particle is they show this in Somewhere in Time did you see it?
JAKE: Nope, what is it?
TYSON: Okay because it was a chick flick that's why JAKE: And I wouldn't say I don't look like the kind of guy who would watch a chick flick TYSON: You are a comic book superhero guy with violence, okay?
JAKE: But hey violence isn't fun remember that it's not fun. TYSON: Okay, so it was a romantic love story, it had Christopher Reeve in it actually. Some old woman comes to him, gives him some kind of a locket and says meet me back in time or something okay and he's a young guy so he figures out how to go back in time and meet her JAKE: Oh yeah. TYSON: And now they're the same age and they have a love affair and he gifts her this locket JAKE: Yeah.
TYSON: Okay, now she has it and gives it back to him, so this is called a Jim particle in time travel. Okay, so this particle was never created, JAKE: Yes
TYSON: It was neither created nor destroyed, it only exists in this time loop. So it's, it's counter to what we think should or shouldn't be in the physical world to which we've grown accustomed, of course. JAKE: Who, where did it come from? Did it just exist?
TYSON:Yes, it just always existed. So with you, with your Terminator loop...
JAKE: Yeah? TYSON: That his act of trying to change it sets the things in motion and that makes it happen
JAKE: Sets it off in the first place TYSON: Right
JAKE: And then it's never going to end, so that's the kind of thing that I have with the example you gave and with Terminator. Is it just one loop that will never end? TYSON: Well you never come out of that loop. JAKE: You never come out of it. TYSON: Well... so in the case of Somewhere in Time, the Jim particle stays forever in the loop, but the characters keep going. What you're saying is, in the Terminator, there were events that affected the whole world, so does the world emerge on the other side? I guess no, because it affected the whole world. JAKE: Yeah, because it's stuck in this loop... TYSON: Right, but (JAKE: And nothing continues on) if it was just some grandmother coming back to meet something then that would be a very contained... JAKE: But would we say then, so this is obviously speculative, but if... So I'm Christoper Reeve, I go back in time.., TYSON: Yes? JAKE: But does that mean everyone around me doesn't have to be the same? They could be different? Or are they stuck in the same loop with me? TYSON: That wasn't addressed in the film.
JAKE: It should have been. These are the questions I wanna know. TYSON: These are the questions. And so in the H.G. Wells' Time Machine ok they dealt with an interesting phenomenon that his love interest dies, she's mugged or something, she's killed in the park. This is why I have a time machine, I can fix this, so she has her go somewhere else and not where the mugger was going to be and then she, like, gets hit by streetcar and dies. He does multiple times, she dies everytime. He concludes that certain events are just writ. JAKE: Yeah, are fixed points. TYSON: They're just fixed points. But, and I thought about it and I said why should her death be any more of a significance than the fact that the mugger now mugs someone else? It's a changed event. JAKE: 'Cause it changes, then, the timeline for all those people. The mugger's life is probably different. That person who's operating the car is now different... TYSON: Just so that you can kill off his love interest. Yeah, just to make that one person die. JAKE: So, it ripples. So, I actually... The Time Machine is an interesting one 'cause, if I remember correctly. I haven't read in a while but I've always thought was interesting how the time machine operates But when he's in, he sees everything moving quickly past him, but I always imagined from the perspective of someone walking by. They're just looking at a man sitting like, in a machine like, okay that's boring no it would be there in an instantaneous instance so he's actually moving through time it's not things moving around him TYSON: Correct, correct. Right right so in some instances he's moving through you would never even see it I mean it would just happen so quickly. That's how I interpret it.
JAKE: Because I thought it was fixed in place like he's stuck on that point in earth so he's not moving.
TYSON: So you're saying I'm here for 10 minutes and I don't budge and so is the time machine. JAKE: Yeah, but from us in the time machine time because it's relative, it feels like we're going...
TYSON: Oh so they should have seen it. JAKE: Yes. TYSON: I'll give you that.
JAKE: 'Cause I always thought with time machines, I'm just going to go to a different point in time. Like, well, the planet's gonna be somewhere entirely different. You're just gonna be in the middle of space.
TYSON: Well, we'll give him that, he's also moving in space. You gotta give him that.
JAKE: Oh, so now he's moving through space? TYSON: Otherwise you can't even, you can't... When Marty goes back to 1985, he'd be...
JAKE: Well, the DeLorean can counter that, it's a DeLorean. I mean, you know...
TYSON: But if he goes back exactly 30 years then Earth is back where it was... JAKE: Yeah.
TYSON: ...in that moment, right? So because if he goes back less than <interval> number of years, then he's out in space. JAKE: Yeah.
TYSON: So here's an interesting problem: so let's say tachyon communication exists, so I can send a signal backwards through time. And, you're walking down the corridor and you slip and fall on a banana peel... TYSON: You know, when I first saw people, you know, cartoon characters slipping on a banana peel... I said "First, why is a banana peel just there, and are banana peels really slippery?" So I kept throwing banana peels over and trying to slip on; I never did, and then I had to realize you have to put the inside... JAKE: Oh yeah.
TYSON: ...down. That has to face downward. JAKE: Oh, you were doing the outside...
TYSON: Yeah! So it's not just slip on the inner slippery surface...
JAKE: Rookie mistake. TYSON: I know, it's a complete rookie mistake. So then I did that, I was like "Whoa, that is really slippery." But if you toss a banana peel it's not gonna just open up and land octopus-style face down on the ground. So you slip on it... I say "Oh, let me warn him." So I send you a text that you get 10 seconds earlier. You're walking down the corridor and your phone buzzes. You pick it up and it says, "Watch out for the banana peel". But now you're not looking where you're walking then you slip on any other reason that happened when I was the reason happened in the first but maybe you do stop me from doing that but now you change the future so you no longer need to send a text message into the past so my past self doesn't get a text message yes what would happen is in Back to the Future style the text will...(disappear)JAKE: Oh it slowly disappears and then for some reason I slowly disappear "Neil what have you done!?" Well, it's interesting 'cause that's... well, it's the butterfly effect Where we've changed the timeline for all we know we could be the rippled different universe compared to what would have been that's like the people who say: "If this one thing didnt't happen to George Washington or to Napoleon or to Hitler then all the world would have been different." And I'm thinking okay I think you're overcrediting this one moment this one incident that they're losing track of the fact that certain forces that are operating to send culture, civilization in a particular direction may be robust to certain changes you might make that you think will make all the difference. "If we past year had not accidentally found found penicillin then millions of people would have died at..." No! You know Betty Lou would've penicillin a year later so...so you pivot everything on this one thing and tell me that all civilization will be different I'm not buying it, civilization is more robust than that and if Hitler were killed as a child then no maybe not, the Germans were ripe to have somebody rise up and take control of their psyche and maybe the circumstances made Hitler not Hitler making the circumstance so that's why you're worried that all of the butterfly effect will somehow veer it this way rather than just be a slightly different thing but in the same overall... JAKE: Of all these kind of things we talked about the butterfly effect seems like the most realistic where it'...it's not something we can really quantify but we can say that... as you were saying; everything happens, like there's always different changes that just ripple throughout history or what is going to be now future NEIL: And I'm saying; it was not this butterfly, it was another butterfly. There was an article in the Journal of irreducible results. It's where scientists who want to take the weekend off from their regular job think up some crazy scientific theory that is just completely stupid but it's scientifically justified so there was an article, it said: "We have captured the actual butterfly that caused Hurricane Hugo." And it's right in... I think in the end I agree with Stephen Hawking, that we will discover a new law of physics that will prevent backwards time travel and we don't know what that law is or why it must exist but everything we can imagine that allows it totally messes everything up you see the the protesters in the street you know with the chant: "What do we want? A time machine! When do we want it? Well, it doesn't matter. Anytime, it'll be fine. So, you can make the argument that if a time machine is ever invented in the future there's no evidence of it having manifested in our past but it shouldn't stop us from thinking about it in fun ways and and thinking about living in this fixed life it's always being born always living out and always dying aight actually take some comfort and then but it-it-it research that your life is predetermined even if it is being a prisoner of the present transitioning from the past to the future I have the illusion of free will and I'm happy to live in that illusion in the knowledge that I don't. JAKE: Thinking about time travel when it comes to kind of predestination or things are predetermined in your life in this path that you lead time travel kind of makes it so that, it is, everything is predetermined...(NEIL: Uhuh, that's right.) ... there's no way to veer off this path everything you do was if I go intelligent machine everything was leading up to that moment the past me will then go and go into the time machine that lets keep happening forever well thank you and also speaking of time you should take some time and go check out Startalk radio there's a link down in the the description or there'll be something popping up probably right between our head link somewhere somewhere here in space and time( NEIL: Star talk) but thank you Neil, thank you so much (NEIL: Dude) it was a pleasure dude and as always thanks for watching
