The Life Scientific: Claudia de Rham

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1:04My guest today has quite an unusual relationship with gravity. While she spent her career exploring its fundamental nature, much of her free time has involved trying to defy it, from scuba diving in the Indian Ocean to piloting small aircraft over Canadian waterfalls. Her ultimate dream was to escape gravity's clutches altogether and become an astronaut, a dream that was snatched away by an unlikely twist of fate. But Claudia Durand has no regrets. I've had to defy gravity for most of my life, she says, in an effort to understand it. As professor of theoretical physics at Imperial College London, she now grapples with deep mathematics, where the fields of particle physics, gravity and cosmology meet, on a quest to understand how the universe really works.

1:53She's a pioneer in a subject called massive gravity, which might take us beyond even Einstein's theory of relativity and shed light on why the universe is expanding at an ever-increasing rate. Claudia de Rame, welcome to The Life Scientific. Hi, Jim. Very good to be here. Now, here on Earth, we all experience gravity every day and we can't escape its clutches. So what is this mysterious thing we call gravity? That's one of the most profound questions there is. What's really, to me, beautiful and fundamental is that it's actually very universal. even if in outer space we can't escape gravity. It's always there.

2:29People will be familiar with the experiment where you drop a hammer and a feather and of course they fall at different speeds. So it does seem like gravity is acting in different ways but that's not the case, is it? That's not the case. In fact, there's lots of different things happening. There's the friction of the air but if you were to do the same thing on the Moon not because gravity is any different on the Moon it's just the same but there's none of the other distractions like atmosphere on the Moon. And so that has been done actually during the Apollo missions. An astronaut dropped a feather and a hammer and they fall exactly at the same rate.

3:03They hit the ground at the same time. They see, exactly. And it's beautiful because it tells us that gravity is completely unbiased. Of course, it was Isaac Newton who first described gravity as this universal force with the simple example of the apple falling from the tree on his mother's farm, explaining that it was for the same reason that the moon goes around the Earth. That's right. That's such an incredible realisation. The same load governs the whole universe. So it's a unifying force that overpowers everything. It's interesting that its description is implicit in its name, yet that's not the whole story.

3:37It's true that it seems overpowering, but in fact gravity is weaker than any other fundamental forces of nature. but also it's something that teases us. You know, this is the first thing we can experiment with as a kid. In dropping objects over and over again, we sort of like to see if there's a point where we'll stop and maybe we'll behave differently. You like to play with gravity yourself. Perhaps I kept this inner child in myself a little bit more. I love to play with gravity in any possible way. So yes, I learned to scuba dive and there's such an incredible feeling floating in the middle of the ocean.

4:15And there's all this universe around you. I like to go flying also to challenge gravity in the air. But I would have loved to become an astronaut, of course. We're going to come to that in a little while. But let's go back, Claudia Durand. You were born in Lausanne in Switzerland in 1978. When you were just two, your parents moved with you and your siblings to the city of Ayacucho in Peru. What took them there? They were working for sustainable development organisations, developing farming of alpaca in the Andes. Do you remember much about that time? Oh, I remember a lot of it. The farmers, I do remember the incredible scene of the Andes.

4:54It's very musical, very colourful, but also very quiet in a more spiritual type of way. I have this lovely picture in my mind of my father carrying some baby alpaca. And I was thinking, oh, I wish I was an alpaca. He spent a lot of time just travelling around, working with the farmers there. This was the early 80s, a period of huge unrest for Peru at the hands of the far left guerrilla group, the Shining Path. Do you recall much of that? I do remember a lot of it, in fact. As a child, it was sort of normal that this movement just grew and grew and we had just to fold to the way we were. I remember when darkness started in my head, I counted till 10, and then everything would go wild.

5:38And I could hear screaming and shouting. They would be shooting through the streets. And it was sort of normal. We would just go under our bed and we would wait for it to pass in the morning. My brother and I would go in the garden and we would simply count the bullets that had gone through the gate. and you have a measure of how dramatic the night had been in counting the number of bullets that had gone through the gate. You say it became normalised, but how do you think it affected you? I think it's only in taking some distance to it that you realise this is not normal. That was the same for my parents.

6:15For them, they were incredible because at no point did I feel from their side that there was any stress. It was only after a few years that we received a notice from probably one of the members of the Senderos Luminados saying that we had 24 hours to leave, otherwise they would take the kids. And so my mother just packed the car and we left overnight and that was it. And it's only when she was in the car driving through the Andes, through the night, we were there in the back of the car that she stopped and she realised that that was just crazy. It's only in hindsight. It's only in hindsight. Absolutely.

6:51So you had to move. So we moved to Lima after that. and that's where we stayed for a few more years. Well, it wasn't long after this, Claudia, when you must have been about five years old, that you started to take an interest in the sky above. Yeah, so after we moved to Lima, we did quite a few trips to the Amazonian forest and I think trying in the hindsight to put an order in all of this chaos, I found some real moment of peace in just contemplating the sky and I remember we were going in the forest and we slept on a hammock in the night, swinging a hammock and it was just at dawn looking at the stars that were just starting to pop in the sky.

7:31I could see the moon and I thought, I just want to be out there. I just want to be on the moon. This feeling of peace and blissfulness. You saw the moon maybe as some sort of sanctuary from the unrest that you and your family were living through. I think so and there was some level of comfort in realising that you will always be governed by the same sky. this was some structure that made sense of everything around me. Was that also around that time that you decided you wanted to be an astronaut or did that come later? This was the seed really even if it wasn't phrased in that sense that I want to be part of this environment in a more fundamental way and therefore be out there.

8:09Well your family finally moved back to Switzerland. You're now one of five children but before long you were all on the move again this time to Madagascar and it was there that you started to experiment with gravity. Yeah, so I started scuba diving very early on and I have one of the fondest memories of this weightlessness sensation. All the fishes around you don't really realise that you are any different and that was something very important to me. In all of these changes, it is sometimes difficult to feel like you're part of something. But even the ocean couldn't keep you from this fascination you had with the skies above you.

8:50How were you able to explore that while in Madagascar? So yeah, the sky was incredible in Madagascar. And so when I was a teenager, I started volunteering in the observatory of the university. I was working there at night. And after a while, they would let me show tourists around and show them a few objects in the sky. That was one way to start exploring. And of course, with this keen interest in astronomy, you returned to Switzerland in 1997 to study physics at the École Polytechnique Federal de Lausanne. What was that like? Somehow I thought it would be completely smooth because I knew this was where I was from, but I never felt as much as a foreigner at that time.

9:32So you didn't feel Swiss. Where did you feel you belong? I think throughout my life I belong to where I was and I think that's why it is important to rely on for instance the sky because that's where we all belong at the end of the day. I was going to say I'm thinking back to the five-year-old Claudia looking up at the moon maybe you felt you belong more naturally living on the moon. When I was in Switzerland that's really when I thought okay I really need to go on the moon. And at university studying physics I gather you felt like an outsider in other ways too. Physics is not the most diverse of the fields.

10:09There wasn't so many women, for instance, studying. There was no woman lecturer or professor. It's sometimes a little tiresome to need to justify yourself. Were there occasions when you actually had to do that? There were definitely some cases where I've been asked why I was there and if I wanted to find another place. Because they couldn't believe that you were actually studying physics as a woman. Yes. It happens less and less now because I'm also a bit better known and I'm older, I guess. But when I'm going to conferences, I've been taken for the administrator or people ask me to refill the coffee because why else would I be there?

10:46By the time, I was much more confident, I think, and I almost took it as a challenge. Well, let's get back to your university course. You were still fascinated with gravity and decided you wanted to study it by observing the universe at large. so astronomy but you changed your mind why was that i did an internship at nasa and it was just amazing and just thinking i can go to nasa and i'm gonna be working with data for my new space probe in fact i realized what i would like to do is much more understand what is governing all of this information and so i realized i really want to go to theoretical physics this is radio but i am nodding vigorously because i was exactly the same partly because if i stepped into a lab i broke things.

11:28If you break the maths, it's fine. You can fix it more easily. Well, by 2001, Claudia, you'd completed a master's degree. But instead of going straight on to do a PhD, you headed off to Indonesia to train as a dive master, the black belt of scuba diving. Yeah, that seems completely normal to me. I remember everyone around me was like, are you crazy? You should just start your PhD straight away. And I was no, this is completely natural to now work as a dive master. And I'm really glad I did it. Well, the following year, you moved to the UK to study for a PhD in theoretical cosmology at Cambridge.

12:05Oh, it was such an exciting time. So the idea that it's not enough to base yourself on three dimensional space, there could be other dimensional space out there, typically so small that you don't feel it in everyday life. The presence of extra dimension would have all sorts of implications for the evolution of the universe, for instance, the expansion of the universe. And of course, we should say that this was just a few years after the big discovery that not only is the universe expanding, but that expansion is speeding up, which I think many of us physicists regard as probably the single most exciting and unexpected discovery in cosmology of our lifetimes.

12:42That's right. This expansion of the universe is going faster and faster. And so somehow it's going against the gravitational pull in which we thought would make this expansion slow down. We're going to come back to that in a moment. But after your PhD, you moved again, this time to Canada, to become a research fellow at McGill University. And the move to this new team required you to shift emphasis from thinking about the universe at large down to the tiniest subatomic scale, quantum physics. So at the time, the way we approached questions and understanding the connection between particle physics and its effect on gravity was quite different.

13:21So that was an incredible opportunity to adapt and translate a little bit to different perspectives, like a patchwork. You get everybody's perspective and from there, you build your own understanding of reality. By this point, of course, you'd also met Andrew Tolley, who later became your close research collaborator, and I should say also your husband. One of the challenges of being a researcher is having to move around a lot, chasing short-term research posts, as of course you had to do. So how did you both make your relationship work? There was a lot of motion, there was a lot of travelling through different airports.

13:58Amsterdam was like my second home and every time we went through the airport we would pick up one of those little wooden tulips and after 10 years when we finally settled down and got married we had so many of these little wooden tulips that we decorated our whole wedding venue and gave them to all of our guests for our wedding. It is famously known as the two-body problem in academia when both partners are looking for it. Exactly. It's a two-body opportunity, but it is really much a challenge when you're living through it.

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15:30Well, in 2006, you took up a joint research position at both the Perimeter Institute for Theoretical Physics in Waterloo, Ontario, in Canada, and also at McMaster's University. Your interest, of course, was the nature of gravity. And while you're getting to grips with gravity on this fundamental level, you were still keen to experience it more directly, with the goal of eventually making it into space as an astronaut. You were already an experienced scuba diver and you'd been holding out for a chance to learn how to fly as well. So finally in Canada, I could start taking a flying lesson. It was just incredible.

16:07I would wake up super early before work when it was dark. I'd go flying. It was a single engine aircraft. You feel absolutely everything, every bump of air. And you go over it, you do feel it in the difference of pressure. The thermals lift you up. And when I would train, I would go with some of my colleagues And it was just an incredible bonding experience because we would drive to the airport and would have all sorts of heated discussions on one problem or another of research and disagreeing. And then we would go on the plane and all of a sudden they actually had to trust me. Flipping the plane?

16:43I mean, when you train, you train to stall and to go into spiral dive. You don't try to do that on purpose with your colleagues. I wasn't that mean. Of course, you'd also hope to one day travel to space. This came a step closer in 2007 when rumours began circulating about the European Space Agency, ESA, that it would soon be launching an astronaut selection round. How did you prepare for this? I had been waiting for this my whole life. So I knew that the most challenging part of it are the psychophysical tests. So a lot of those tests are actually based on Lufthansa piloting tests. I didn't have access to those tests.

17:21No one does. But I tried to code my own test myself so I could train, so I could put myself in the best position. Whether it helped or not, I don't know. Well, the following year, 2008, the moment you'd been waiting for had arrived. The European Space Agency announced the astronaut selection round. I was in Canada at the time, so I sent in my application. Then there was a whole batch of different psychological tests and team bonding where we were put in stressful situations. You had to take part in a jungle mission as well. Yeah, pretend mission. It's very much about testing your ability to cope with stress, but also how you work with others.

18:02I remember I was sitting with my partner waiting for us to go through one of those tests. the pair before us just came out of it shouting at each other and you just think well that's probably not gonna work well you did make it through to the last 42 how did that feel for the first time it felt like oh my goodness this is actually getting sort of real and when i started going through all of the actual medical tests which were much more physical they were much more intrusive you'd realize in fact it is myself as a person as a body that put myself in this situation and it started to become really real and you could feel it also with the other peers because it was very much a team.

18:44Any one of them you knew you could put your life in their hands and you'll be fine. They were the most collaborative, open and really generous people I ever met. You say you had to go through these medical tests. How did it go? At the end of the week I had a meeting with a doctor in charge and he sat down with me through all of the results. He was scanning through them, said, this is fine, this is fine, this is fine. So he closed the file and he looked at me and said, you know, they're going to need a woman. And for the first time, I thought, wow, this can actually happen. And we started laughing and he said, yeah, you know, we're just missing one test, the TB test result, because it takes a few more days.

19:27I'll get back to you with that. And I thought, okay, I think if I had TB, I would know. And he laughed and said, well, you never know. I'm sure I'll be fine. So I went back to the airport the next day, just boarding the plane. In fact, I took my phone to switch it off. And so the results of the test were there. So I opened the email and my heart just sank because there was a note from the doctor, the TB test had come positive, latent TB, which meant I had been infected in the past. My body had fought it, developed antibodies, and the tests had detected those antibodies. It's fine. It just means your body just adapted to it.

20:06So you must have caught it at some point. I probably caught it in Madagascar. It was very common in Madagascar. So even though you weren't ill with TB, you knew it was all over? I knew it was all over. There was no coming back from that. Can you remember how you felt sitting on that plane? Not great, I have to say, I knew there was no one to blame. There was nothing other to understand. It wasn't something that should have done differently. And that was the way it was. In 2009, Claudia Durand, following this disappointment, you then threw yourself into your research on gravity. And at a cosmology conference at CERN in Geneva, you had the opportunity to present a paper.

20:45Yes. So at the time, it was just a parallel talk in one of the sessions, nothing very important. my husband-to-be at the time, Andrew, he was presenting one of the plenary talks, big shot, very, very exciting. And then there was also another colleague of mine, Gregory Gabadazzi, who was presenting in the grand finale of the conference. And because he was a big deal, he was only coming the last day of the conference and his talk was to be determined. And the night before his talk, the title of his talk and the abstract came out online. And I saw that a month or so earlier, he had actually submitted a paper, which was almost identical to what I had presented.

21:26So in fact, I had been scooped. So I sent him an email and I said, can we talk? Because this is very similar. And rather than telling me, he was the most welcoming person you can imagine. And we started discussing precisely about that idea. And then he invited me to join him in New York University where he was. And we started collaborating and actually it was the most incredible collaboration very very creative collaboration and in fact Andrew your husband also then joined the collaboration later exactly but it's interesting isn't it because here you are working on this new theory called massive gravity which we're going to come to in a moment but there's three of you you're in Geneva Gregory's in New York Andrew's still in Canada I know from doing research particularly in some an area like theoretical physics it's much better to be there in the same room in front of a blackboard That's right.

22:18Scribbling things down and arguing. Exactly. So when I would go and visit him at NYU, this is really when most of the work had been done. But he was just great in saying, OK, we think we have an idea. We think it works like that. Let's just do it. And it doesn't matter if it's two in the morning. We just keep on working till we have the answer. And so we kept going. We kept going. There was no working day. No, there was no. OK, let's take a step back for a moment to examine how your theory of massive gravity came about and what it tells us. Of course, being a theoretical physicist myself, there's a danger we're going to slip into technical details.

22:52So we're really going to try and keep things simple. What we learn at school is what's called Newton's law of gravity, right? This invisible force of attraction that pulls everything together. But Einstein improved our understanding. He replaced that picture with his general theory of relativity, which says that gravity is really about the curvature of space-time. Lots of physicists would say Einstein's theory is the final word. but you wanted to go further. Why was that? So we already know that there are situations where Einstein's theory of relativity is not the final answer, for instance, at the Big Bang, at the very centre of black holes.

23:26So we need to go further. We also, as a community, realised that the expansion of the universe was accelerating. And so the idea was to try to understand whether this acceleration could be accounted for by going beyond Einstein's theory of general relativity. And of course, at the time, it was thought, and still to a large extent, that this accelerated expansion of the universe is due to something called dark energy. However, your theory, massive gravity, changes how we view the accelerated expansion of the universe and the impact of dark energy. So let's unpack this idea just a little bit. You see, for listeners, the name massive gravity suggests something big.

24:07Certainly, it works at the very larger scales. But you mean it in the scientific sense, massive as in something having a mass. And in this case, it's a tiny, tiny particle called a graviton, which we believe is the tiniest lump of a gravitational field, a quantum of gravity, just like the photon is the quantum particle of light. Most physicists would say that just like the photon, the graviton doesn't have any mass at all. But your theory suggests it might have a small mass. That's right. At least it's an exploration of what the consequences would be if it had a small mass. So what would the consequences of this graviton particle having mass have on dark energy, which we believe is causing the accelerated expansion of the universe?

24:55So it will diminish its effect. It's like putting a rain on dark energy. The real issue with dark energy is we have in fact far too much of it. And so this small mass on gravity will change the effect of this huge amount of dark energy. So it's possible to account for this excess of dark energy, or even do it at all together, if only the graviton had a small mass. That's right. Well, after two years working on this, in 2011, you and Gregory Gabadadzi and your husband Andrew Tolley published your new groundbreaking mathematical framework for this theory of massive gravity. Now, the year before this, you posted your paper online as a preprint, so before it's gone through peer review, so that the scientific community could comment on it.