Best Of: The Science And Stories Of Time Travel

0:07Have you ever fantasized about going back in time to relive a moment or change it? Maybe you're more interested in traveling to the future, where cars fly and the code to immortality has been cracked. If the idea of time travel resonates with you, you're far from alone, particularly during a year of political upheaval. I love the time travel series Outlander. Now watching season seven, I'm finding their treatment of the American Revolutionary War period to be especially timely, given the 250th anniversary of our experiment in democracy. I also have a lot of Scots blood in my ancestral lines, so the series has given me a lot of Scottish history, too.

0:52I love that time travel can be a hook into understanding the past, not only one's family history, but also one's beloved and democratic country. Thanks for that message. This year, scientists move one step closer to understanding time travel, at least hypothetically. Two physicists at the University of Queensland in Australia laid out a model for studying the phenomenon. So no, we're not there yet, but when it comes to books, movies, and TV shows, that's a different story. Wait a minute. Wait a minute, Doc. Are you telling me that you built a time machine out of a DeLorean? The way I see it, if you're going to build a time machine into a car, why not do it with some style?

1:37Your mom is just a tiny little thing. Goes out to the clearing. And there's a man there. With no clothes. Not a stitch on him. And after she gives him a blanket she happens to be carrying, he explains to her that he's a time traveler. This is going to sound strange. Be prepared for strangeness. Get ready for spooky time. But there's this family secret. And the secret is that the men in the family can travel in time. Well, more accurately, travel back in time. We can't travel into the future. Those were clips from the films Back to the Future, The Time Traveler's Wife, and About Time. Today, we're defying the laws of 1A to bring you a mashup of the 1A Movie Club and our series The Scientific Method.

2:28to unpack why we return to stories about time travel and whether it will ever become a reality. I'm Jen White. You're listening to the 1A Podcast. Stay with us. We've got a lot to get to.

2:44Joining us from NPR headquarters in Washington, D.C. is Regina Barber. She's the co-host of Shortwave, that's NPR's science podcast. Regina, welcome to the program. Thanks. Also with us is Jana Levin. She's a professor of astronomy and physics at Barnard College in Columbia University. She's also the author of several books, including Black Hole Survival Guide. Her substack publication is called Extra Dimensions. Professor Levin, it's great to have you back. Thanks for having me. I'm glad to be here. And Jonathan Russell-Clark. He's a literary critic and the author of An Oasis of Horror in a Desert of Boredom and Skateboard.

3:18Jonathan, welcome to the program. Thanks for having me. We'll talk about specific films later, but I'd love to start by asking you, Regina and Jonathan, about what first drew you to time travel stories. Regina, I'll come to you first. Okay. Yeah. So I am a reporter now, but I am an astrophysicist as well. I think I like astronomy. I think I like time travel because it's like cause and effect, right? Like, it's a very scientific thing that you see something happen and then what is the result of that? I mean, I also like, you know, futuristic fantasies. I'm a big Star Trek nerd. You know, I like this idea that maybe, like, Star Trek is very utopian.

4:00You know, like, maybe in the future we have the answers to save our planet, to, like, travel distant places. So I think I like the futuristic kind of travel, probably more time travel. Jonathan, what about you? I think to me, and actually, you know, as a lot of, which as is true of a lot of critics, I'm a failed fiction writer. So when I was young, time travel appealed to me as a storyteller. It's so, it's got, it opens up so many possibilities for narratives. And I think I was excited by that more than the science part of it. What kinds of questions do you think time travel stories allow us to explore, Jonathan?

4:40I mean, that's sort of the interesting thing is for how complex and mind-boggling time travel is always presented to us in these stories. The actual themes that they address and questions they address are so basic. They're so basic human longing. And the biggest question they always answer is, what if I had made a different choice? Could I see myself in a different situation. And time travel stories always involve somebody confronting or a group of people confronting different versions of themselves, different choices they could have made. Professor Levin, every time travel story is different.

5:19But from an astrophysicist's perspective, what do these movies and books typically get wrong about time travel? Yeah, well, I appreciate the Professor Levin formality. Please call me Jana. Okay, we'll do, we'll do. People under 20 call me Professor Levin. What do they get wrong? It's funny because I've just started to clock that I'm here for scientific accuracy, but I also love it for the narrative potential. Okay, will do. But I will say one thing, and I think what Jonathan said was very interesting because these are fundamental issues that we think about. What were my choices? Do I have free will?

5:56And so I think what a lot of time travel stories get wrong is the idea that free will is somehow outside of the laws of physics. This kind of idea, if I'm on a consistent time loop back, that I could make a different choice this time. And that suggests that somehow you're bound by the laws of physics to go back in time, but your mind or your will or your freedom is not. And I think that is something to be challenged in these stories that could make them even have more texture. And one of the interesting films, which you did not mention, is 12 Monkeys, where no matter what they do, they make the same choices.

6:39They're on the same. There's no, oh, I did something different and there's a different outcome. They're inevitably bound against everything they're fighting to do the same thing and be on the same path. Yeah, now that you mentioned 12 Monkeys, it's about a group of people trying to prevent a disease outbreak of catastrophic proportions. And yeah, that one's a bit, it's a bit twisty. Well, one of the most well-known time travel movies is the 1985 classic Back to the Future. It stars Michael J. Fox as Marty McFly. He's a teenage boy who gets trapped in the 1950s when his parents first met. Doc, you disintegrated Einstein.

7:17Calm down, Marty. I didn't disintegrate anything. The molecular structure of both Einstein and the car are completely intact. Where the hell are they? The appropriate question is, when the hell are they? You see, Einstein has just become the world's first time traveler. Back to the Future turned 40 years old this past July, which makes me feel a little, a little old. But Regina, you have what you call a hot take about this franchise. There are three films in the series. And you think the third one, which takes Marty back to the Old West, is the best. Why? That's my favorite one. And let's just make sure that the listeners know that Einstein is their dog.

7:57Yes, yes, yes. So they aren't traveling around with the human Einstein. It's the dog's name. And they kind of send the dog into the past first because, you know, like we do with animals, you know. But I would say the third one's my favorite just because I was born in the 80s. And I don't really remember when the first two came out. So the third one was like kind of the first one that I remember, you know, going to the theater and everything. And it's a Western. And I think a lot of people kind of downplay the Western. They don't really give it a lot of love. I think it to me, it was more appealing than futuristic 2015, which did not pan out to be correct.

8:40Not at all. At all. But I like how when Doc Brown went back into the Wild West, right? He talks about people running for fun, and you also see water not being filtered. I think there are little things in that movie that aren't really played up in other time travel movies. Also, Doc Brown has feelings, and a lot of the movies have this mad scientist stereotype that I very much dislike. And in this last one, he actually has a love interest. He has despair. He gets to trick out a train. Spoiler alert, he has a happy ending. You know, like, I really liked it. I think people need to give it more love, definitely.

9:27Let's take a quick pause here. Coming up, we discuss a film that does successfully explain the logistics of time travel, at least according to two of our guests. We'll be right back.

9:41Now, Jonathan, you think that Back to the Future is an example of a time travel movie that doesn't work. Why not? Well, I think, I mean, Back to the Future in a lot of ways established what are the really common tropes for time travel stories that we all kind of understand. You know, the betting book, the almanac, sports almanac, the idea of being erased in your future if you don't get things back to the way they were, all those kind of tropes. But it also introduces so many logical and inconsistencies. And if you ever watch young people talk about this movie, if they watch it on podcasts or something, they just start pointing out things like the fact that they're the McFly's that he goes back to.

10:36But it's his mother's side of the family. when he goes back to, you know, like back to the past. You know, they look like his mother, but she's named Nick Fly. The idea of when he goes back to the West in the third one, you know, there's now two DeLoreans back then because the one that Doc traveled with and then the one that Marty travels with, but they, so I don't know. It's just all these kind of inconsistencies that come from time travel. All the Back to the Future movies are just filled with those. I mean, and it's a comedy, it's a light thing, so they're not interested in those. But I just can't help but see all those inconsistencies.

11:18Well, Jana, in many movies and books involving time traveling, including Back to the Future, there's often this concept about interfering with the timeline. This shows up a lot in Star Trek, too, the space-time continuum. Does that exist in the real world? Well, I think what everyone's pointing out in reminiscing about these movies is that the inconsistencies in the film are the same as the inconsistencies in physics. There's not a new set of rules for physics that we're using. I mean, there are different criteria sometimes, but honestly, everyone's just expressing the same ones that as physicists we have to impose.

11:58Is it consistent? Is it paradoxical? You know, the laws of physics are very strict. They require certain things. But technically, the laws of physics, according to Einstein, do allow us to go back in time. At least they allow one particle to go back in time under very extreme circumstances that we've never matched in the reality that we live in. An entire universe that circulates around one point. That's not the universe we live in. You know, there are certain negative energies you could create wormholes. And technically, as mathematical solutions in Einstein's equations, one particle can make it through and go back in time.

12:37But none of these are situations that we know are possible in our reality outside of the math. But even that's intriguing, right? So even Einstein was like, huh, that's weird. And, you know, one of the questions is, will nature protect us? Is there a chronology protection? and Stephen Hawking talked about this as a conjecture. Maybe nature just won't allow it. But what we will have to have is consistency. And that's the bar that the films and the narratives and the stories have to rise to is internal consistency. Well, a 1992 film Encino Man is about a teenager who finds a caveman in his backyard who's been frozen in a block of ice for thousands of years.

13:30Okay, my friend. Try and experience when I'm about to chirp in your lobs. Okay, cool? Okay. Today, buddy, we're going to discuss grindage. How to fill the furnace, pack the cheeks, and stuff the gills. Okay? You're probably used to eating twigs, right? But out here in the U.S. of age, buddy, we got something called the Four Basic Food Groups. Now, Regina, this is a film you specifically wanted to talk about because you'd think it handles time travel terribly. Why? Yeah, I mean, well, it was funny. I was asked this question, and then the first, like, bad time travel movie that came to mind was this movie.

14:05And one, we don't really think about it as a time travel movie because there's this frozen caveman. But he's going into the future, right? Like, he has, you know, been frozen and then reanimated, which we cannot do, right? I mean, if we could, you know, space and time travel would be easier. Well, space travel would be easier. But I mean, I guess that's in other movies and stuff. But you heard Pauly Shore talking in that clip. I mean, I barely understand him and I lived that, right? Like, would Encino Man understand our language? Probably not. Like, would he want to kill you? Maybe. You know, like, I think, like, it's interesting because it's, like, so ridiculous.

14:51But I do like that it's going forward in time. So that's why I'm counting it as a time travel movie. But, like, this whole idea of just somebody being frozen instantly, it's interesting. But it's done not. It's a comedy. It's ridiculous. You can travel forward in time. We, you know, we can, Jana can talk about that some more, but. I mean, we're doing it right now, Jana. We're traveling forward in time. I can travel to your future almost no problem. I mean, it requires a lot of energy, but that's absolutely scientifically confirmed that I can travel to your future. I haven't yet understood and nobody knows how to, for me to travel to my future.

15:35Wait, okay. So for instance, you know, Einstein's relativity says that if I travel really fast or if I'm, you know, very far from the earth, that your time will slow relative to mine. And there are ways where scientifically completely verified we can do it at the level of particles and almost at the level of people. I can travel to your future. I can go on a trip and come back and you'll have experienced many more years than I will have. And we see this even with our electronic devices, that they have to correct for this time dilation between the satellites that are both moving very rapidly and are further from the Earth, that they're experiencing a different passage of time than we are closer to the Earth and relatively stationary relative to those satellites.

16:26So this is verified. Your GPS unit would not find your Uber if we did not correct for the fact that our times are misaligned. Um, so weirdly I can, through special relativity and general relativity, travel to somebody else's future, just not my own. Wow. Wow. Well, we're hearing from lots of you. Kevin writes, in my opinion, the closing scene of Back to the Future 3 is one of the single greatest scenes in movie history and the best one ever with the steam locomotive. I was absolutely blown away when I saw it in the theater. I'm a 53-year-old man and I still cry during the last 10 minutes. Well, Well, Regina and Jonathan, you both wanted to discuss the 2004 independent sci-fi movie Primer as an example of a film that pulls off time travel exceptionally well.

17:15And it's about two engineers who accidentally discover time travel. Here's what's going to happen. I'm going to read this. And you're going to listen. And you're going to stay on the line. And you're not going to interrupt. You're not going to speak for any reason. Some of this you know. I'm going to start at the top of the page.

17:36meticulous, yes, methodical, educated. They were these things. Nothing extreme like anyone they buried. There were days of mistakes, laziness, and infighting. That's the film's director, Shane Carruth, a former, or rather the film's director, Shane Carruth, is a former engineer and has a degree in mathematics. Jonathan, what do you think this film does especially well when it comes to handling time travel? I think it does two things really well the first is a practical thing the second is a narrative thing the practical thing is the characters can't travel in time in this machine unless there's a machine where they're intending to go so they have to emerge from some machine so they have to build something somewhere where they're going to eventually travel to so there's all these interesting logistical things it addresses and I'm sure that in terms of physics, a lot of these things would still not make sense.

18:38But it's just a really interesting thing. And then the other thing it does is it allows the audience to figure out when the characters are traveling in time and why rather than imposing all of those implications or the ramifications of all their time traveling as the narrative. So you're sort of piecing it together, which I'm sure there are still logical inconsistencies and paradoxes in the film. In fact, that's like sort of part of the mystery of it. So I think just narratively, it employs time travel in such an interesting, mysterious way that most movies don't try to do. Nicholas emailed us this, the most consistent version of time travel in media is from Harry Potter and the Prisoner of Azkaban.

19:30It treats time travel in a way where everything that the characters change after traveling to the past happens the first time around. It definitely sparks a conversation about free will because the characters essentially follow in the footsteps of their time-traveling selves without the possibility of anything changing. If time travel to the past existed in real life, I believe this is the most logical explanation of how it would work. This is also why I believe time travel to the past will never exist. Jana, earlier this year, two physicists at the University of Queensland in Australia laid out a model for studying hypothetical time travel.

20:05And this model involves traveling at the speed of light, which we can't do. But what is our current understanding of time travel? Well, we do know, again, this idea that formally on paper, we can find mathematical models where one particle can go back in time, but none of them are consistent with the world that we observe. But it's strange that Einstein's theory allows it at all. It's very strange. And there isn't really some global understanding. We know that we can imagine wormholes, but we don't know the kind of matter that would be required for wormholes to take us back in time doesn't seem to exist.

20:55in reality. But at the quantum level, it's really hard to talk about even time and to even talk about... So there are these quantum experiments where it's really hard to say what happened first or which was cause and effect. So I guess I would, to the listener's comment, I would say It's very interesting, this idea that we simply have to be consistent with the laws of physics, and we simply have to be consistent with the same timeline we were on. And we talked about that a little bit. If I go back in time, why would I be free to alter the laws of physics? That's a tremendous amount of power that the atoms of my body are not given, are not afforded.

21:41Why would my mind be allowed to make choices that are different? There's a famous thing called the grandfather's paradox. if you go back in time and you kill your grandfather before he had children, how could you have been born to go back and kill your grandfather? And very detailed analyses of these sort of suggest, well, maybe you did go back in time and you shot your grandfather and you made him deranged mentally, and so he was a terrible grandfather and father, and so you were so deranged that you went back and shot him. But it's totally consistent. Now, there is one loophole in this, which is this quantum realm.

22:19What if there really are many worlds? What if each decision, and there's nothing special about human decision makers, but each quantum event allows for a different branch? So you don't come back in the same path. You actually come to a different future, and there's a sense in which both exist. You know, people are free to play with these ideas. There's no formal physics that has enough rules or understanding yet that we know how that plays out. Let's take a quick pause here. We'll be back with more of the conversation in just a moment.

23:01Well, let's go back to our inbox. We got this message from Mike. I'm just calling in about the time travel prompt. what do I like about it in cinema and film or stories. And the one that comes to mind for me is Interstellar by Christopher Nolan. I think that just the concept of space and black holes and realm beyond our Earth and how it's all involved and how love is behind all of it really was captivating and how that was conveyed in that movie, Interstellar. Mike, thanks for that message. Regina, you hate the film Interstellar. Why? I don't hate it. Let's be real here. Okay, I don't hate it.

23:41It's just that when you're an astrophysicist around that time, when you teach physics and astronomy, everyone was talking about it. And I finally watched it. And it's really long and really slow. And I agree with the listener that love is the answer to life. I agree with that. But it's not the answer to astrophysics. And I didn't like that. the physics is good I think that getting the like the most like accurate depiction of a black hole was amazing it's not like a like a funding grant proposal would have been able to justify that so I'm thank you Hollywood for giving that to us but like I I think I think it was very good but we actually interviewed for shortwave Erin McDonald she's the Star Trek franchise like astrophysicist consultant, and she said this thing that I never thought of, that Interstellar might have reduced the public's confidence in science because every scientist in the movie was kind of dubious.

24:38And I never thought of it until now. And I'm wondering what Jana thinks about that because I didn't even think of that. They're all kind of liars. Jana, have you seen Interstellar? Yeah, of course. You know, the film was originally, the treatment was written by the great physicist Kip Thorne, who won the Nobel Prize in black hole physics and wrote the original treatment with Linda Opes, the great producer who had been doing science films since Contact and passed away recently. And so there's real depth to the ideas in the original treatment. And Kip used formal physics with the filmmakers to render the black hole.

25:22And it was incredibly accurate. Because of that, it was a mathematical model. It wasn't just a CGI. And I know those equations very well. You know, I've worked on that very well. And one of the interesting things that they turned off was the color. So you know this idea of blue shift and red shift. When a horn comes towards you, it sounds higher frequency when it goes away. Lower, same thing with light, comes towards you, it's bluer, hotter, away from you, redder, cooler. They turned off the color. They didn't think it was as aesthetic. So it's a purely white image of this material swirling around the black hole, but it's actually formally very accurate.

25:58So I'll give them that. The idea of whether the scientists were dubious and untrustworthy, I don't really remember, but I guess that's quite right. They're all kind of up to something, aren't they? And then I guess my attitude in that is that they're just not acting scientific. You know? And that's kind of the history of science. We build weapons and the people who use them aren't behaving, they're not behaving scientifically. There's other motivating factors. We're not pure in our thoughts and hearts and minds. Jonathan, you wanted to talk about Donnie Darko and that's a 2001 sci-fi thriller about a teenager named Donnie Darko who sleepwalks out of his house one night during the 1988 presidential election and sees a giant, demonic-looking rabbit named Frank.

26:4728 days. Six hours. 42 minutes. 12 seconds.

27:05That is when the world will end. Now, this is one of your favorite examples of time travel in a film. What makes it work for you? I think the thing that makes it work best is that it doesn't tell you it's a time travel movie. That's not revealed until, you know, spoiler alert, it's not revealed until the end of the film. And what you discover at the end of the film is that it's essentially a Christmas Carol, you know, type of story. It's a Wonderful Life, where this character is shown what would happen if he lives and survives this thing that occurs when he sleepwalks. And he sees what will happen, which is the death of this girl he meets and really falls for.