TED Radio Hour - Doppelgangers

Episode Date: February 9, 2024

The term can refer to a double, a ghost, a shadow. But it can mean much more. From our online mirror world, to digital simulators, to the Earth's twin--TED speakers learn from the uncanny second self. Guests include author Naomi Klein, aerospace engineer Karen Willcox, planetary scientist Sarah T. Stewart and psychologist Nancy Segal.TED Radio Hour+ subscribers now get access to bonus episodes, with more ideas from TED speakers and a behind the scenes look with our producers. A Plus subscription also lets you listen to regular episodes (like this one!) without sponsors. Sign-up at plus.npr.org/ted. See pcm.adswizz.com for information about our collection and use of personal data for sponsorship and to manage your podcast sponsorship preferences.NPR Privacy Policy

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From TED and NPR. I'm Manoosh Zamorodi. On the show today, Dupelgangers. You know that moment when you catch a reflection of yourself before your mind is ready to believe that it is you? This is Naomi Klein. She's a best-selling author,

a big thinker type who's written about climate change, corporate power and feminism for over 20 years. She has made a name for herself, or so she thought. We all want to believe that we have some control over how the world sees us. We polish ourselves and try to perfect ourselves and perform ourselves. And when you're being confused with somebody else on an industrial scale, you realize that you just can't control it at all. For Naomi, the mix-up started about 13 years ago during the Occupy Wall Street protests.

And I was there because I was writing my book, This Changes Everything. And during one of those protests, I went to a public restroom and I was in a stall. And I overheard two women talking about me in very unkind terms. Basically, they were trashing me and saying, you know, did you read me? that article Naomi Klein wrote, oh my God, like she completely does not understand our movement. And I was just sort of mortified and it brought back every mean girl experience in high school. I had a lot of mean girls at my high school. And then gradually it dawned on me that they were not actually talking about me.

They were talking about another Naomi nonfiction writer. So I came out and said to those two women, I think you're talking about Naomi Wolf. You have your Naomi's confused. So, mistaking Naomi Klein for Naomi Wolf, it's not entirely surprising. Both are best-selling authors. Both have written sharp critiques of patriarchy, capitalism, global corporations. Naomi Klein even remembers idolizing Naomi Wolf in college when Wolf's debut book, The Beauty Myth, came out.

She was 28 years old when the beauty myth came out, and she wore leather jackets and had amazing hair and looked like Valerie Bertonelli. And I just thought, you can make a career out of sort of trashing patriarchy. And I was inspired by her, to be honest. Yeah. And she was named Naomi. So I was like, could I do that? So, yeah. In the early 2010s, the Naomi's got mixed up a lot, especially on Twitter.

And mostly, it was kind of funny, maybe a little annoying. But then things took a turn for the weird. I think it had been happening gradually since 2014 in particular. where she started to have different conspiracy theories about Edward Snowden, about Dominique Strauss-Kahn, about chemtrails and clouds. The confusion was still relatively harmless. That is until the pandemic struck. It accelerated a lot during the pandemic because my doppelganger, Naomi Wolf,

is one of those people who really fell down what I see as a disinformation and misinformation rabbit hole about the pandemic, casting it as a bio weapon that was cooked up in a lab in order to destroy the West. Then she said much the same about the vaccines and the vaccine verification apps and became a star on the far right. And was suddenly on Steve Bannon's show every day. A coup situation, a police state situation. And that's not a partisan thing.

And so people would scream at, me about this and get very angry at me. What, like, what, what, what happened to you? Or else they would praise me and say, about tell me how much they loved my appearances on Tucker Carlson. What has become, you know, the best idea since World War II for enslaving the world, you know, the Western world. What were some of the ideas that were being attributed to you? Do you remember offhand? That I thought masks were making children lose the ability to start. smile, that I thought that having to get vaccinated was a coup d'etat that people who've been vaccinated

no longer smell like humans. Someone was extremely upset with me because I had supposedly claimed that the vaccine verification apps were like Jews being forced to wear yellow stars. under the Nazis. And so I just wrote, you know, this is, are you sure about that or keep your Naomi straight? I mean, to be blamed for that must have been really upsetting, not just creepy. The whole thing was a very strange experience. I think I felt one of the most recurring doppelganger feelings, which is just helplessness, because you realize that you just can't control it at all.

And that there's somebody out there who's doing all of these things that people think is you. And there's not a thing you can do about it. Anything you could do to try to set the record straight will just make it worse. We'll just increase the association in people's minds. I no longer felt that I could participate in the public version of me. And I just watched, watched the idea of me merged with the idea of her in the ether.

And it all just slip away. The word doppelganger is German, literally translating to double walker, as in your ghost or shadow. We often use the term to describe two people who look similar in an uncanny way. But in our high-tech world, it can mean so much more. And so on the show today, ideas about doppelgangers. From the mirror world that our online virtual selves live in, to digital twins being built to predict and treat things like cancer. And the mystery of why the moon and earth are, in fact, twinsies.

So back to Naomi Klein. She ended up writing a book about her experience called Doppelganger. It's a cultural critique of the world. the online world that commodifies our identities to dangerous lengths. It just struck me that having this confusion out there and out there on the internet of people confusing me for somebody else who was not me was a way of talking about something that was much less specific to my Naomi problem and was more universal to the way we're all kind of confused about whether we have control over ourselves at all in the digital age, right?

You know, one of the things that I did is part of this research trip is I watched a lot of films about doppelgangers and read a lot of novels about doppelgangers. And I was really struck that, you know, for filmmaker, everyone from Charlie Chaplin with the Great Dictator to Jordan Peels, films like us that really work with the figure of the doppelganger, they're often used as a way to capture the menace of a society that is flipping into a doppelganger. of itself. And specifically the kind of fascist double that exists on the, that always lurks on the edges of a liberal open society. We know that it can flip. We know that it has flipped. And I feel that fear, right? And so, and the fact that my doppelganger has turned into a doppelganger of her

former self, right, had changed so dramatically, had gone from being. this prominent feminist, you know, a Democrat who had advised Al Gore when he ran for president, you know, had really been a big deal on the center left, could now be paling around with Bannon and Carlson and, you know, really consorting with some nefarious characters. Like people are constantly writing these articles, whatever happened to her, what, like, as if she was visited by, like, became like a Stepford wife, right? it just struck me as an interesting way to explore that sense of menace. It really is possible for us to turn into a collective doppelganger of who we think we are.

There is a passage in your book where you start to grasp the reach that Naomi Wolf was having online. Would you mind reading that for us? Sure. I admit that when Wolf first started talking about vaccine passports as mass surveillance networks, I really didn't understand the effect it was having. I was focused on the many wrong facts she was sharing, as well as the true fact that her newfound celebrity on Fox was blowing up my own social media. What many of us who were cringe-following Wolf at the time missed was the extent to which her new messaging had

struck a chord, not only with Fox's audience, but also with a sizable cohort of people who identify as leftists or progressives and were terrified of the Black Mirror surveillance world she was describing. Tell us more about what you're writing there and how it, what you started to understand was the reason why people who you would have agreed with or would have been fans of started to share conspiracy theories that felt outlandish. Yeah, well, in the book, I say that conspiracy culture often gets the facts wrong, but the feelings right. And this really struck me when Wolf took her star turn on the right, it was when she started to

claim that the vaccine verification apps that we all downloaded onto our phones, and for a were scanned to get into restaurants and concerts and things like that, that these were actually part of some kind of nefarious plot that involved the Chinese Communist Party and Davos and Bill Gates to bring what she called a CCP Chinese Communist Party social credit system to the West and that if we did this, it would be a fascist coup and our government would be able to listen to our phone, not our phone conversations, but our real-life conversations in restaurants. We'd be under surveillance all the time. And she became

a star on the right for this and a laughing stock, you know, on the liberal left for this. And the sort of snarky comeback about all of it was wait till they hear about cell phones. A lot of the conspiracies of the COVID era were about surveillance, were about the idea that this was the way to get us all tracked. They were tapping into this all-pervasive fear around a huge loss of privacy that we've all experienced because we've gotten addicted to our cell phones in this way. And we don't know what happens with our data. We don't really understand what happens with the data that's collected on Google Maps. And that is creating an opportunity for conspiracy to spread. That really taps into those deep and latent fears.

When we come back, Naomi Klein on how conspiracy theorists profit by tapping into those fears. On the show today, doppelgangers. I'm Manus Shumerodi, and you're listening to the TED Radio Hour from NPR. Stay with us. Hey, listener, before we get back to the show, I just want to let you know our next bonus episode for TED Radio Hour Plus is coming out soon. It's my conversation with Lily Singh. She's an actor, comedian, and former late-night TV host. We talk about all kinds of things, like what it was like being the first bisexual woman of color to host a late-night show.

Yeah, she has a lot to say about all the boxes that she's been put in. And what it was like when she finally did get to host late night. Wow. Anyway, that is coming Wednesday. If you're not a TED Radio Hour Plus supporter yet, please. join your fellow listeners to get all kinds of bonus content and all our episodes sponsor free. Just go to plus.npr.org slash TED or give it a try right in the Apple Podcasts app. And thanks.

It's the TED Radio Hour from NPR. I'm Manusse Zamorodi. On the show today, doppelgangers. We were just talking to writer Naomi Klein, who has spent much of the last decade being confused with the writer Naomi Wolf. I think I felt one of the most recurring doppelganger feelings, which is just helplessness. This mix-up started causing a lot of trouble for Klein,

especially when Wolf began touting dangerous conspiracy theories. The World Economic Forum, the World Health Organization have united to create a new world order in which we are dead or disabled or sterilized. Why would ideas like these attract people like Wolf, who had never. never leaned extreme right before. I say that conspiracy culture often gets the facts wrong, but the feelings right. Klein says liberals and her fellow progressives failed to acknowledge all the pandemic fears from

masking, vaccine mandates, surveillance, to rising inequality and corporate profiteering. This provided an opening. And I think the failure to do that really rolled out the red car. for the right to do this kind of what I call a mix and match, right? Well, they take a few of traditional kind of left-wing issues. There are days when Steve Bannon sounds like Bernie. There are days where he sounds like me, you know, and then he mixes it with anti-immigrant xenophobia, with anti-black racism, with this whole very nefarious right-wing agenda

and an authoritarian agenda. So I started listening to Bannon, but then found myself just. interested in how he was creating what I called a mirror world of everything in the world that I recognize, mirror publishing companies, mirror social media companies, mirror arguments, mirror currency. But I was also struck by how he would perform a certain kind of inclusivity and kindness, which I think would surprise people who only see clips of Bannon online where he's sort of roaring ferociously about how he's going to, you know, put the heads. of his opponents on spikes, which is, you know, part of Steve Bannon for sure.

But if you listen to him in greater depth, you see this other side, which where he is part of the opportunism, part of the way he defines himself against the liberals and the leftists is by talking about how mean we are to one another. And how in his world, you know, if you come over, you're going to be treated with kindness. You're going to, there's, and that's why he was so, I think, attracted to Wolf is that it allows him to perform this willingness to be in conversation with somebody who you would think he would be on the other side. So it sounds like you think the liberals, Democrats, middle, whatever you want to call them,

missed a trick here. Oh, yeah. But I do think that it is within the power of the left. the center left to not hand over all of these other issues that are traditionally our issues, standing up to corporations and standing up against profiteering, so that he doesn't have such a powerful cocktail to mix. Do you have any idea what your doppelganger thinks of you? Does Naomi Wolfe, has she made any passing comment or mention of what she thinks of the book or you?

Definitely more than a passing comment. She's posted quite a bit about it. She even has a conspiracy about it, which I'm not going to go into. But she has said that she hasn't read it. So I do wish that she would because I think that if she did, she would find that it isn't what she thinks it is, that it is kinder than she thinks it is and less about her than she thinks it is. So the irony of you writing this book in some ways, is, well, you started out by having a little bit of a brand problem, right, that people were

confusing you with another Naomi. But this book, I mean, I googled both of you, and it's the book that comes up now. In some ways, you have drowned out mentions of the other Naomi, or at least in my Google. Is it possible to ever really confront your doppelganger? I mean, was that your intention? Confronting your doppelganger in literature and art always ends badly. Edgar Allen Poe, Dostoevsky. Dorian Gray. Oh, my God.

If you try to stab your doppelganger, you will end up bloody on the ground. You know, I think the only way out of a doppelganger tangle from what I can tell is really to earnestly believe that a mirror is being held up to you that you have to look at. with some honesty and willingness to see a side of yourself that you might not like to see. You know, I often say that sometimes when people describe doppelgangers, they say that it's like looking into a living mirror. But in my experience, it's much worse than that. It's like, because you haven't been able to prepare your mind yet to believe that it's you. You don't have your mirror face on. You don't, you know. And you have to be willing to accept that that might

actually be you. And that there's a reason that you're getting confused, that it might be trying to show you something. It might be a challenge to change if you don't like what you see, right? And I'm trying. I'm trying. I'm trying to learn from it. I guess I'm wondering, do you have advice for people who are listening about how to think of their double gangers or their different identities in the world? Should they beware? Should they be kind to them? My only advice is to cling a little less tightly to the self you think you are. Yeah, and at the end of the book, I quote Iris Murdoch, the British novelist and philosopher, who talks about unselfing as almost a transcendent state where when we behold beauty,

whether in the natural world or in a piece of art, when we allow ourselves to be transported, by it, what we're doing is we are forgetting about ourselves. And I think it's true that we can really only behold the beauty and tragedy of the world when we are able to unself and not think what does this mean to me, what can I post about it so that people think I'm the right kind of self. But when we actually just get out of the way and unself and show up, Yeah, that's what my doppelganger journey taught me in it, and I have to relearn it about six times a day.

That's Naomi Klein. Her latest book is Dopplganger, a trip into the mirror world. You can watch her talks at ted.com. And by the way, we reached out to Naomi Wolf for her comments and did not hear back. On the show today, Doppelgangers. Okay, guys, going to the moon. Good evening. America, and welcome aboard, Apollo 13.

On April 11, 1970, the historic U.S. spaceflight Apollo 13 launched. Okay, Houston, we have lamb extraction. Maybe you saw the 1995 movie about it. With Tom Hanks, Bill Paxton, and Kevin Bacon. Houston, we have a problem. And remember that scene? The pivotal scene, when the oxygen tank explodes on board. It's got to be the oxygen.

Stranding the astronauts in space. And sending the mission into turmoil. We've got a computer restart. I'm going to configure the RCS. It was a disaster. The world watched as the astronauts drifted further and further away from Earth. How to get the spacecraft back on track and come home. Well, NASA had numerous simulators on the ground that were being fed data from the real space.

aircraft 200,000 miles away. So let's get to work. Let's lay it out. These simulators could replicate what was happening on board. I mean, the exact same conditions we've got in there now. And strategize how to get the astronauts back safely. Let's not make things worse by guessing. It helped NASA predict and then execute the return mission that brought the astronauts home. Hello, Houston. This is honesty. It's good to see you again.

Today we have a word for a souped up version of NASA's simulators, digital twins. These are computer simulations that are constantly being updated with real-time data, and the technology is getting much more advanced. Instead of the astronauts sending data back to mission control, aircrafts and their simulators, for example, can send data back and forth, mirroring and guiding each other. What really makes a digital twin special is that that virtual representation is connected to the physical world, and there's a bidirectional flow between the virtual and the physical.

This is aerospace engineer Karen Wilcox. And then that digital twin is now becoming a personalized dynamic virtual representation, which in turn can be used to drive new decisions. You could have a digital version of your home and track how your energy, costs would rise or fall if you went solar. Car companies are building digital twins of their new designs to see how they'll respond under different conditions. Karen says the applications for digital twins are endless.

But remember, she's an aerospace engineer. And so she's pretty excited about how they're being used in her field. I want you to think about the digital twin of my aircraft. Here's Karen Wilcox on the TED stage. So as I create that digital twin, I'm going to. to be collecting data from the sensors on board the aircraft. I'm going to be collecting data from inspections I might make of the aircraft, and I'm going to be assimilating that data into the models.

And what's really important is that I'm not building a generic model of just any old telemaster aircraft. I am building a personalized model of the very aircraft that is right now sitting in my garage down the road in South Austin. And so that digital twin will capture the differences, the variability from my aircraft to say my neighbor's aircraft. And what's more, that digital twin will not be static. It's going to change as my aircraft ages and degrades and gets damaged and gets repaired.

We will be assimilating data all the time, and the digital twin will follow the aircraft through its life. You can imagine in some future world that an operator and airline has a digital twin for every single one of the aircraft in their fleet. And that digital twin is being updated every day or maybe even every hour with data collected from its physical twin so that it is an up-to-date representation of everything that's going on with that aircraft. And it's now able to identify when a problem may be about to occur before you get all those passengers. on the plane. And you can imagine the value in that, that first of all, that keeps us safer. Second of all, it leads to more efficient practices, which saves money. It keeps the engines

running more efficiently, which has reduced environmental impact. So just a lot that can be done by having your fingers on personalized, dynamic, just-in-time information. And predictive, right? Like you could say, well, this time around, the aircraft is going to be fine, but after six more flights to Minneapolis, we need to definitely check this particular part because the model has looked into the future and shown that this is a potential issue. That is exactly right. And the models are really, when combined with the data, what led us predict into the future and to make predictions about conditions that we haven't seen yet. And that's really what drives decision-making. Let's talk about another more important. We're going to

personal way that digital twins are going to be in our lives, and that comes to health care. And my understanding is you have partnered with a group of oncologists to research how digital twins can be used in cancer treatment. That's right. So here at UT Austin, we started talking with the Center for Computational Oncology and the Odin Institute, who are really interested in the idea of digital twins as a way. to move towards personalized cancer care. And as my group of aerospace engineers started talking with the group of oncology experts, begin to really realize that even though the physics, the biology, of course, is very different, there's so many common challenges. So Karen says, picture a patient with a brain cancer diagnosis.

The first step, taking lots of images of their brain. Where is the tumor? How big is it? How dense is it? Using all that data, scientists can build a virtual version of the tumor. We have very powerful models, mathematical models that can represent a tumor and make predictions about how that tumor's going to grow. Is it going to end up pushing on different parts of the anatomy? But here's the crucial goal. Using the tumor's digital twin to predict which treatment it will respond to best, based on so many factors like the patient's anatomy. Her physiology on what's going on with her body,

we think we would be better to frontload some of her radiotherapy and then give her a break in the middle and then go back to high doses. The future vision is really having the digital twin work hand in hand with the human clinician to try to achieve the best outcomes for that individual patient. I mean, that sounds amazing. So you could create a digital twin based on what your cardiovascular strength is and your blood type. And then could you add variations to see how things would go? Like so, for example, if you got chemotherapy and you quit smoking and brought your blood pressure down,

we think we could predict that your outcome would be X. If you didn't do those things, here's what that could look like. That kind of thing. That's absolutely the vision. we're still a long way from being able to get to that point. You can imagine that as human beings, our biological systems are so incredibly complex. And we still don't yet have the computational power to be able to model a full human where we could really start to connect all those different things you mentioned.

But what you described, absolutely, this is the vision. So that's the health of a human. But explain how the same sort of model. applies to improving the health of our planet. Yeah, absolutely. A future vision is, could we one day have a digital twin of planet Earth? Being able to have a digital twin at the scale of full planet Earth goes well beyond what we can do today with our models and our algorithms and our data. But I think this is a fantastic vision because it also starts to think about integrating all those disparate pieces

of our planet Earth that we know are connected so that we really start to make decision-making in a holistic way as a planet rather than as individuals or individual nations. I mean, that word holistic, that really seems to capture the promise of digital twins when it comes to solving all these big problems like mortal illnesses and, gosh, climate change.

That's exactly right. So this sounds like a huge challenge, and indeed it is, But the good news is that we have a lot of hope for addressing this challenge. And a big part of this hope rests on this notion of predictive physics-based models that let us make predictions, predict how an Antarctic ice sheet might flow under different future temperature scenarios, to help guide decisions about where to drill ice cores,

where to take observations, and ultimately to inform the decision-making around our future climate. I hope you're excited like I am about the idea of a digital twin and maybe as you go home you can look around and think, oh, what if we had a digital twin of that? I personally could not be more excited about a future world where digital twins are enabling safer, more efficient engineering systems. They're enabling a better understanding of the natural world around us and they're enabling better medical outcomes for all of us as an individual.

Thank you. My digital twin would have told me at 47 to enjoy red wine because within the next couple of years, my body would not be able to metabolize it as well. The prediction would have been there and you could have taken that trip to Tuscany before it was too late, right? Right. Exactly. That was aerospace engineer Karen Wilcox. You can see her full talk at TED.com. On the show today, doppelgangers. I'm Manus Zamoroti, and you're listening to the TED Radio Hour from NPR.

We'll be right back. It's the TED Radio Hour from NPR. I'm Manoosh Zamoroti. On the show today, ideas about doppelgangers, twins. So on a clear night, you might look up at the sky and wonder, what is our connection to our closest neighbor up there, the moon? The Earth and the Moon have a special relationship, and it's different than anything else we see.

see in the solar system. We think of it like the Earth and the Moon are identical twins. This is planetary scientist Sarah Stewart. And what she means by identical twins is that the Earth and the Moon are made of rocks that have the same isotopes, basically the same geological DNA. The Earth and the Moon have nearly identical ratios of isotopes. And so they definitely had different. lives after they were formed, but they must have been made from the same original materials,

the original rocks floating around the sun. And this is really unusual. No other pair of bodies in the solar system has this same relationship. And that's been a big puzzle to explain. So the prevailing theory about how the moon and Earth formed has been around. for years. But it never quite explained how the two could be made of the same materials. And this really bugged Sarah. The leading idea for the origin of the Earth and Moon is called the Giant Impact Theory.

Sarah Stewart continues from the TED stage. The theory states that a Mars-sized body struck the young Earth and the moon formed from the debris disk around the planet. The theory can explain so many things about the moon, but it has a huge flaw. It predicts that the moon is mostly made from the Mars-sized planet, that the Earth and the Moon are made from different materials. But that's not what we see. The Earth and the Moon are actually like identical twins. When I started working on the origin of the moon, there were scientists that wanted to reject the whole idea of the giant impact. They didn't see any way for this theory to explain special relationship between the Earth and the Moon.

We were all trying to think of new ideas. The problem was there weren't any better ideas. All of the other ideas had even bigger flaws. So, Sarah and her team wondered, maybe the giant impact played out differently. Maybe all those billions of years ago, things smashed together, in a way, no one had considered yet. They needed to find out. Yeah, my lab is called the shop compression lab.

It has two huge cannons that we use to generate pressures like those generated by planets colliding together. We smash stuff together and we zap them with lasers and we try and recreate what happened in the early solar system. Can I just ask you, this sounds. dangerous. Is this dangerous? Absolutely. That's what makes it so much fun. Awesome.

The team did all kinds of simulations, and one day they saw something that they didn't recognize. I remember distinctly where we looked at the computer data, and when we were looking at it, what we were seeing was something that was much, much larger than the Earth, meaning its radius was many times bigger. It was hot and mostly gas in the outer layers. What was this new hot, gassy thing? So imagine a glowing ball of swirling gas. From the side, it looks kind of like a...

Like a frisbee? A bow tie. Oh, a bow tie, okay. Almost like a bow tie. There's a knot in the middle That's where most of the earth is, but then it flares out at the edges. So looking from the side, that's the shape it would be. And it would be glowing, bright, like a fire hearth, because the rock in it is magma and rock vapor filling this object.

Can I just make sure I'm with you? Yeah. So there's an impact. Something hits very early planet Earth. to the point where it actually changes shape. It goes from being round like a ball, spherical, to flattening into more of a disc and having more of a gaseous sort of look to it, less firm edges, very blurry around the edges and almost like on fire, very, very hot. That's right.

So when the Mars-like object struck the earth, so much energy has been dumped into the planet that it's so extended and spinning so rapidly that it morphs into a disk in its outer layers. And it no longer has that spherical shape, and it no longer rotates altogether. It's so large that the moon would begin to form inside of that swirling gas. We had to come up with a name for an object that's not a planet. We named this new object

a senestia. It's named after the Greek goddess Hesdia, which is the goddess of the hearth and home. A senestia gives us a new way to solve the problem of the origin of the moon. We propose that the moon formed inside a huge vaporous senescia. The moon grew from magma rain that condensed out of the rock vapor.

The moon's special connection to Earth is because the moon formed inside the Earth when Earth was a senestia. The moon could have orbited inside the sinestia for years, hidden from view. The moon is revealed by the synestia cooling and shrinking inside of its orbit. The senestia turns into planet Earth

only after cooling for hundreds of years longer. In our new theory, the giant impact makes the senestia, and the senestia divides into two new bodies, creating our isotopically identical Earth and Moon. So your theory explains why they are twins. But if the moon and the Earth came from the same fiery situation, why do they look so different? Right. The twin analogy isn't perfect for the Earth and Moon because we do see such stark differences. All of the water and gas that become our oceans and atmospheres, they are bound to the larger object.

It had the larger gravity field. And so the Earth has the richness of the oceans and our atmosphere. And when the moon separated from the synestia, it separated without an atmosphere. It was a molten ball with rock vapor only, but didn't have the carbon dioxide that made up Earth's first atmosphere. So the two paths of the planets diverged after they separated from one another. And the level of precision is now at the point where we can see little differences on each planet that reflect processes that happened after their origin in addition to their origin. But it sounds like there's still a lot to learn, a lot you don't know. Well, the more we see.

So we scientists have a burning desire to explain how the Earth got to be the Earth. And the moon forming giant impact is a key event in the history. of Earth and perhaps may have been important in why Earth is the habitable planet. So I think we'll continue trying to understand the details of what made the Earth and Moon because of the importance of explaining the Earth. So can I just ask you, when you look up at the Moon, I'm guessing you see something or you think something very different than what I do or most people. Yes, I spent a lot of time pondering what it would be like when everything was mixed together.

And at that time, all of the atoms that we have today and the two bodies were mixed together and swirling together. And me sitting here today and you sitting here today, we're part of that. Our atoms were swirling around with moon atoms, and that's just an incredible thing to ponder. I love that. It's what makes this event so special and so personal for all of us that we were part of it, even if it was a deep history of our existence. That's Sarah Stewart. She's a professor of planetary science at UC Davis and a MacArthur Genius Award winner.

You can see her full talk at ted.com. On the show today, doppelgangers. And we want to end this episode talking more about. about twins, but the humankind. For decades, identical twins have been observed and studied by researchers trying to answer the age-old question. What is nature and what is nurture? Nancy Siegel is a professor of developmental psychology and the director of the Twin Studies Center at California State University, Fullerton. Here she is on the TED stage in 2017.

Let's talk about twins. Twins turn heads wherever they go. Society tells us that we all differ in appearance and behavior. So when we encounter two people who look and act so much alike, it challenges our belief in the way that the world works. We find ourselves intrigued and drawn into twins' lives, trying to understand them. For most of human history, psychologists believe that we are largely products of our environment. The twin research is teaching us that so many more of our behaviors than we ever would

have imagined are influenced by the genes. There are two kinds of twins, identical and fraternal, and both are essential in twin research. Identical twins result when a single fertilized egg divides within the first 14 days after conception, and these twins share all their genes in common. fraternal twins share half their genes on average, just like ordinary brothers and sisters, and they result when a woman releases two eggs at the same time that is separately fertilized by two separate sperm. We can compare the similarity of identical twins in running speed

or in how fast they solve math problems to the similarity of fraternal twins. And if identical twins are more alike, and they usually are, this tells us that the genes play an important role. Now, most studies use identical twins raised together, but studying the rare pairs of identical twins rear it apart is even better, because if identical twins raised apart are as alike as identical twins raised together,

this is even more compelling evidence that genes are important in our development. Think about the identical twins. identical Jim Twins, Jim Lewis and Jim Springer, who grew up in different Ohio cities. They didn't meet until they were nearly 40, and they discovered that both twins bit their fingernails down to the nub. They both drove light blue Chevroletes. They both had mixed headache syndromes beginning in their teenage years, and they both liked to vacation on the same three-block strip of beach in Florida. The Jim twins also both named their sons James Allen.

Now, James is a fairly common first name, but Alan is a much less common first or second name. Both of the twins had worked part-time in sheriff's offices and part-time at McDonald's. And they loved to scatter love letters around the house for their wives. And in a curious twist, both twins had married women named Linda. divorced them and married women named Betty. But then one of the Jim twins divorced Betty and married Sandy.

We know the divorce is a partly genetically influenced trait, so you can imagine the worry, the part of the remaining Betty. And I also studied Barbara and Daphne, the Giggle Twins. My colleagues and I affectionately call them that because when they met for the first time, they discovered that they laughed uncontrollably with each other and with nobody else. And they had the same crooked pinky fingers,

the same disinterest in politics, and they drank their coffee cold, black, and without sugar. These twins had had a first miscarriage in their first pregnancy, followed by two healthy boys and a daughter. That may not be so surprising, because female physiology may, in fact, the sex of our children, and in this case, the physiology was perfectly matched. I finally want to mention two sets of identical twins, males,

born in Columbia, South America. One pair from the city, one pair from the country. We don't know how this happened, but early on in the premature nursery, one newborn twin was accidentally exchanged with one newborn twin and the other pair. So these two sets of brothers grew up thinking they were fraternal twins, when in fact they were completely genetically unrelated.

When they were 25, the truth was discovered and the real pairs were reunited. I went down to Bogota to study them, and I discovered that the personalities of the reunited twins aligned almost perfectly. In one case, the twins were outgoing, gregarious, wrist-tecouvered. and in the other case, they were introverted, little cautious, little restrained. Again, we don't fully understand the reasons behind these similarities, but seeing them repeated and identical twins, more so than fraternal twins, gives us a genetic perspective on human development.

Twins are not just mere objects of fascination, just by being themselves, just by acting naturally, to give science a powerful tool for understanding genetic and environmental influences on behavior. And in this way, they tell us about our humanity, why we are the way that we are, and how we got that way. Thank you. That was Nancy Siegel. Her latest book is called Deliberately Divided Inside the Controversial Study of Twins and Triplets Adopted Apart. She, by the way, is also a twin, the fraternal.

all kind. And you can see her full talk at ted.com. Thank you so much for listening to our show, Doppelgangers. This episode was produced by James Delahousie, Katie Montalione, Matthew Cloutier, and Fiona Guren. It was edited by Sanaz Meshkampur and me. Our production staff at NPR also includes Rachel Faulkner White and Harshanahada. Irene Noguchi is our executive producer. Our audio engineers were Robert Rodriguez and David Greenberg. Our theme music was written by Romteen Arablewee. Our partners at TED are Chris Anderson, Michelle Quint, Alejandra Salazar, and

Daniela Balezzo. I'm Manoosh Zamorodi, and you have been listening to the TED Radio Hour from NPR.