Science Friday - The Leap: You Do Realize… That’s Impossible

Episode Date: June 23, 2025

As a grad student, Suchitra Sebastian wasn’t sure she wanted to be a physicist. But when one of her experiments gave an unexpected result, she was hooked. Suchitra’s former PhD student Beng Sing Tan describes the late-night experiments that led to an “impossible” finding—a potentially new state of matter. Theoretical physicist Piers Coleman tells us about working on the edges of a scientific field, and what happens when a new theory ruffles old feathers.“The Leap” is a 10-episode audio series that profiles scientists willing to take big risks to push the boundaries of discovery. It premieres on Science Friday’s podcast feed every Monday until July 21. “The Leap” is a production of the Hypothesis Fund, brought to you in partnership with Science Friday.Transcript is available on sciencefriday.com. Subscribe to this podcast. Plus, to stay updated on all things science, sign up for Science Friday's newsletters.

That was the moment when the discovery happened. And at that point, I called a senior colleague. And there was a pause. And then he says very kindly, but you do realize that's impossible. Like, I know, but all I can tell you is it's what's happening. And yeah, over the years, people told me that in less kind of fashion, Like, clearly something was wrong with this finding.

This is The Leap, a series about gutsy scientists who are risking their careers, their reputations, and even their lives to discover something new. People often describe science as a method for generating new knowledge about the world. Another way of saying that is that science makes the world feel like less of a stranger. Finding by finding, we get to know the world a little bit better. And in that way, science can be a comfort. But that's not always how science goes. Sometimes a discovery does the exact opposite. It makes our world feel more alien.

It thrusts us into the deep unknown. It suggests what we knew for sure isn't a sure thing at all. So if you make a discovery like that, how do you navigate in those uncharted waters? How do you make sure you're not pulled under? by an old way of thinking. It's scary. Like there's the fear or the discomfort

of being unfamiliar, not knowing what's happening. But that's the only way you will find something new. This is Cambridge University physicist Suchetra Sebastian. She made a discovery like this, a possible new state of matter.

It was baffling and strange and pushed her into the limelight of her field, which was a surprising place to find herself because for a long time, So Chichita wasn't sure she wanted to be a physicist at all. Looking in physicists, it kind of seemed like physics was their whole world. And I just didn't see myself as that person. Academics, like, sleep in their offices. And this is terrible. I do not want to be. And yeah, that sort of singularity didn't make any sense to me. So Chitra's path to

science had some wiggles. She grew up in India, went to a Christian liberal arts college, where she got involved in theater and activism and got interested in physics. But she wasn't sure she was cut out for that career. So after college, she got an MBA, became a consultant, and found that wasn't her calling either. She missed learning, being in school. So she applied to grad school at Stanford for physics, and she got in. And I still did everything because I discovered this loophole that when they said you have to take 50% of credits, they didn't say what. So I took it in theater.

And I was involved in a lot of activism. So, yeah, I continued to do everything. So I really enjoyed grad school. But I didn't find, like, a specific research thing I wanted to do. So I was still actually not sure whether I would continue the PhD or anything. I was still, yeah. And then in the fourth year, I found a result that didn't match. And that was when I actually understood what research was about.

It's like, oh, that's great. so things don't do what they're supposed to do. So then suddenly I started showing up in love my supervisor. Like, what happened? Where have you been? Who are you? Yeah, like burning the candle both ends. It was very funny.

Sounds like a drug a little bit. A good drug. But like, you know, like there's probably some dopamine hit from being like, whoa, new thing no one's ever found. Yeah, like first you go through the period of, I don't know what is happening. This is really confusing. to this is really exciting.

The field that lit Sucha Chitra up was condensed matter physics. It's not easy to sum up, but think of it like this. It's how tiny components of matter, the atoms, their electrons, interact with each other in mysterious ways to shape the world that we see and touch and feel. Sucha's PhD discovery, a material doing a weird magnetic thing no one had ever seen before, landed in the journal Nature. It gave her a direction, and soon she was on a role,

making other big findings. But even though she was successful, she didn't feel like she belonged. It is really like cutthroat. It's like dog-eat-dog. It's like all you care about, if all you care about is the physics, then you will do anything.

Can you give me an example of that dog-eat-dogness? Oh, yeah, like smaller versions of it are like not giving credit to someone, presenting your results without recognizing that other people's results exist. But also, in the, physics, anyone, whether it's me, whether it's someone else, if they report something new, you know the instant reaction is going to be to tear them down, is to find what's wrong with it.

And just the fact of constantly being attacked, like constantly being on the defense, like knowing a conversation is never just a conversation. Like when you report something, it's never just like, oh, look at, you know, this interesting finding. It's always what could be wrong with it, which goes as rigor. but is really taking someone down. And so Chitra felt pressure to fit in with this culture. It definitely felt like, yeah, do physics in the way we expect you to do,

which also meant be the kind of person we expect you to be. Crazy things like you laugh too much and I'm like, well. Someone told you you laugh too much? Oh, yeah, yeah, yeah. A couple of times it's been said to me. It's very sexist. So I was very confused by this because I was like, I am not an aggressive person.

I'm not like going out and trying to make you do things in my way. I'm just existing. Why are you so upset just at who I am? Physics is one of the most male-dominated fields in STEM. While the gender gap is closing in other sciences, like in biology and chemistry, the gap in U.S. college physics majors is still wide. Four to one, men to women. In 2021, about 80% of full physics professors who are men and the overwhelming majority,

white. While that stat has improved, there's no question that there's a dominant culture. And I've questioned it. Like I've spoken to people about it a lot of times when they say, why are there no women in physics? I'm like, look at how toxic it is. Why do you think people would actively choose this? And then they would say, oh, but, you know, that's needed for good science and people are, you know, emotional and they get heated. And I'm like, no. And they're like, there's only so many spots in academia and of course it's competitive. I'm like, yeah, there's competitive. This is not just competitive. This is hostile. But every time it gets justified to me, like, the culture has to be like this for good science to happen. And I think, how about all the people

you've lost? You don't know all the people who are pushed out of this culture and they might have made the biggest contribution. Because for people like me, it is toxic. So Chichra tried to adapt. Initially, I would try to mellow myself. I'd be like trying to, I guess, be a little more under the radar. So I was like less picked on.

Like laugh less? Yeah, yeah, yeah, yeah, yeah, definitely. You know, it's a small compromise here or there. Like not even talk about the fact that like I did theater. activism or I go to church. And when I would go to experiments, I stopped doing that. But yeah, also, like, talkless, be more mellow. Like, be, like, a little more, like, the scientists would gravitas that they expected you to be. Compromise by compromise, so Chichra was becoming the very person who turned her off of physics as an undergraduate, that physicist who'd give up anything for their research.

And that transformation was hard to face. I never wanted to recognize to my, that physics had become the most important thing. Because all through my career, all through my life, of course, I was like, no, it's not. And at every level I knew I didn't want it to be that. But it is, it's unrelenting. And that was a very hard moment to recognize that if it was not the most important thing, then I had to be willing to walk away from it. Because I think that was always what was being held over.

you do it in this way or you can't progress in physics. What was the most important thing if it wasn't physics? Oh, I think knowing that there's something bigger, knowing that there's like purpose in life, meaning to life, being Christian, knowing that actually there is a greater purpose that is not people's approval and really that people are not your audience, like they're not your judge. It's interesting to hear you talk about Christianity and religion in this way, because I think for some people, it can be so stifling and, like, prevent them from being their full selves. And it's interesting to hear that for you is sort of the opposite.

Yeah. I completely recognize why people think this. I think a lot of the time how Christianity is practice is it's very judgmental. But I think for me, being Christian, knowing there's a greater purpose is what frees me to explore, to do things that are not popular, to step out into the unknown, to take risks knowing that research is going to go well, it's not going to go well. The experiment's going to work. It's not going to work. But that isn't what defines you. Did you have a moment where you recognize this and decided to make a change? So yeah, there was a moment, but it was just me in my apartment, literally like breaking down being like, I cannot do this anymore.

Something has to give. And I will do things in the way I'm doing them. And not just in physics is who I am. And if it means I don't do physics anymore, so be it. And I did make that decision. And of course, like, it's not been like easy, but actually I became my creative best when I wasn't constrained. And it was very freeing. So Chichre was free to make a leap.

Which brings us to the state of Florida. We were at Tallahassee. We were the high magnetic field laboratory in Tallahassee. This national lab is home to the strongest magnet in the world. And a super strong magnet is one of the ways to reveal how the electrons in a material are moving, which is why Suchitra is there. So high magnetic fields in this case are like a magnifying glass to make the oscillations much bigger. That's the physics term for the paths of electrons, oscillations. They're also sometimes called very adorably.

Wiggles. Yeah, wiggles. And from how fast the wiggles are, how big they are, how big they are, what shape they have. You can say something about the trajectory, the parts the electrons are taking. So we were in Tallahassee using these very big magnetic fields and looked to see if we could see oscillations. Which sounds chill when you hear Sitcher describe it, like pop in the sample, let the machine do the work.

But that is not the vibe of these magnet runs, as they're called. Magnet runs are actually very, very tiring affairs. This is Bengtan, Sucetra's former PhD student, who was on this magnet run. You really need to be very flexible, and very nimble because sometimes your measurements fail for some reasons

or that you get results you didn't expect. It's high stakes. You plan for months or more. You only get a certain amount of time to use the machines. Things break. Experiments fail.

You're troubleshooting around the clock. So typically in the magnet run, I have an average of maybe something like three or four hours of sleep every night. And there was one night. All I remember was there. We didn't sleep for the night.

So we just worked throughout the night. night and continue the next day on the next magnet run. Bang says Sucha Chitra always seemed to have an infinite well of energy during these runs. It's amazing how Sucha Chitra can always get through all this with all the enthusiasms and excitement that she has. And does it seem to get tired? It's like, I don't know where she gets all her energy from. So in Tallahassee, Bang and Suchetra were studying this crystal called Samarium hexapuride.

And in very niche physics circles, it kind of has celebrity status because, it behaves in bizarre ways. Physicists like to put things in boxes, and this material doesn't fit neatly. For instance, sometimes it seems to be an insulator. Its electrons are largely stuck in place and no current passes through it. And sometimes it acts like a metal,

the electrons flow, it conducts current. Its weirdness required new theories to be devised. And by the time Bang and Suchitur were working in Tallahassee, one leading theory was that the inside of the crystal as an insulator while the surface is a metal. This is really strange, but okay, people could get their minds around it. So, So Chitra decides to kick the tires on this theory. So we go ahead and we mount the sample and so we take it up to high fields. The resistivity doesn't do anything. As expected, the bulk of the material acted like an insulator. The electrons were not moving. But then they took a different

measurement and saw something that did not fit with any existing theory. There's a wiggles on the data. And this is completely confusing to us. The wiggles were coming from the inside. That means the electrons were moving. So basically, one measurement says the electrons are stuck. The other shows the electrons are moving. And so it's impossible if they're almost stuck in place. How could they be going round and round? So the first feeling that Suchitra has is not like, ooh, joyful, I discovered something big and new. It's panic. I mean, the first reaction is definitely something has gone wrong because it doesn't fit what I thought would happen. Like, you know, if it's a little bit different than what you expect, that's okay.

Like, okay, you know, I can believe that. But if it's completely different from what you expect, the first few things are always, like, something has gone wrong. What should I check? Then you check all the obvious things. And then you think of what else have I not thought of that I should check. They ran the experiment again and again, changing variables, doing every check could think of asking collaborators what checks they should do. And each time, the data suggested

this material was doing something no one had ever observed. It didn't seem to be an insulator on the inside and a metal on the outside. It seemed like the inside was acting like an insulator and a metal at the same time. That's a magical moment. It was a magical moment. Yeah, because we're really not expecting to see that kind of oscillations at all. Yeah. So it's really quite Amazing. Yeah, it becomes a moment of like, wow, this is amazing. Like, we've discovered this thing that literally, like, rewrites textbooks. Like, that's excitement.

Samarium hexaboride was strange before. Now it was baffling. And at that point, I called a senior colleague, and there was a pause. And then he says very kindly, but you do realize that's impossible. It was heretical. Yeah, because what we know about insulators has like stood for decades. What we know about quantum oscillations has stood for decades. And so basically it means everything we thought we knew about an insulator is not, right?

By simply reporting this finding, Sucher was suggesting that those boxes that physicists use to make sense of the world, maybe they're not right. Maybe we need a whole new box. See, in some sense, she proposed something that was completely avant-garde. This is theoretical physicist Pierce Coleman, who sometimes works with Cichita and has studied this material for decades. A hypothesis requires a certain amount of madness because you're going to be making an idea, which by its very nature is one that is contrary to perhaps the common viewpoint. And so what is avant-garde about the strange experiments that Cichita and her colleague, have been engaged in, is it seems to suggest that a central element of a metal is present in an insulator.

That's the paradox. That's the paradox. And I think, according to conventional wisdom, it's completely impossible. And that's what makes it so fascinating. The data such a trip-up forward suggests that maybe electrons can behave in a way we didn't know was possible. It is a result which, if it's true, will constitute a new state of quantum matter. And we don't know for sure yet. But if it is, it does require a new idea. It really does. Many theoretical physicists are trying to resolve this paradox. I'm here in Aspen, Colorado, where we have a center for physics in the summer, and we've been discussing this over blackboards quite a lot in the last few days.

The physics community has not reached consensus on what exactly to make of Suchitra's finding. These super pure crystals that Suchetra has access to are hard to come by. So it's taking time to replicate the result. Also, an impurity in the material can create oscillations for all the wrong reasons. All of this combined with the fact that the results are so surprising has created robust debate about what to make of the finding. Everyone we talked to said more experiments and more theory work are required to really understand whether or not textbooks have to be rewritten. And this is just the way that science goes. It takes time to build on and validate a new idea. But if the process of science is dispassionate, scientists sometimes are not. There was a lot of pushback.

Like, give me the scale of pushback. Yeah, the scale of pushback was literally, yeah, people standing up in my talk and saying, addressing the audience and saying, but we know from Maxwell's equations, this is impossible. Like I've had like large six foot five guys that come really close to me. in a physically intimidating way and, like, get red-faced and, like, yell at me. So heated. It's like they're going to, like, come to blows over what? Like, some one data point?

When you have Copernican moments, it requires courage. It takes courage because Sucha Tcha is defying conventional wisdom. That's right. And by its very nature, when you have a new interpretation, you don't understand the full details of why your interpretation is right. So Copernicus came up with the idea that the earth is going around the sun, but he had no idea why the earth would go around the sun. And so it takes a lot of courage to, with incomplete understanding,

to make a hypothesis. And that's what Suchitra has done. I may not understand it. I may not be able to explain it. That doesn't mean it doesn't exist. It's not real. I think it is really about being open to what the data is telling you, like letting the data speak,

even if it doesn't fit your template of the familiar. Xi Tsik Tzu speaks about it, the philosopher. She speaks about there being different ways of doing things. And in one way, the goal is that someday we will know all there is to know. It's like a closed map where you're filling in the unknown bits and it's almost like we need to know in order to control. And I don't want any of those things. I want to embrace the unknown and the point is not to know everything.

The point is the wonder and the curiosity and the joy of exploration. And in that way of doing things, it's like the map is... rolling as you go into the unknown. It's like taking a leap, knowing that there will be something without knowing what it's going to be. The Leap is a production of The Hypothesis Fund. It's hosted by me, Flora Lickman, and produced by Annette Heist, editing by Saeed, Tijon Thomas Jr., Pejow Van Gaye, and David Sanford. Fact-checking by Nicole Fasulka, mixing and scoring by Emma Munger, music by Joshua Budo Karp.

Special thanks to Jim Allen and Natalie Walschover. Thank you for listening. Back to our regularly scheduled programming tomorrow with an episode about giant, ancient wombats, what tiny shards of unidentified bone and museum collections can tell us, and some good news for the future of our galaxy. Personally, I can say I prefer the milky way to continue to live, even if there's no impact on my life or human lifetimes.

That's tomorrow on the show. Thank you.