The Life Scientific: Catherine Heymans

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0:30Catherine Heymans:at Whole Foods Market. He's widely recognised as one of the greatest footballers in history. He's won the prestigious Ballon d 'Or award five times. He's the all-time leading goal scorer in professional football. And according to the Bloomberg Billionaires Index, he's the first active footballer in history to achieve billionaire status. Guess who we're talking about yet? That's right. Good Bad Billionaire is exploring the life and fortune of football icon Cristiano Ronaldo. That's Good Bad Billionaire from the BBC World Service. Listen now wherever you get your BBC podcasts.

1:07Hello. They say you can't go wrong opening with a joke. So here goes. Einstein developed a theory about space and it was about time to... OK, my guest is laughing. More likely the listeners are groaning. But my attempt at physics humour is in honour of today's guest, an astrophysicist who understands the power of comedy to make science accessible. Catherine Haymans is a professor at the University of Edinburgh and the current Astronomer Royal for Scotland, indeed the first woman to take on that role in its 200-year history. Catherine studies dark matter and dark energy, those mysterious ingredients of the cosmos that, to the best of our current understanding, make up about 95 % of everything that exists.

1:53Her work has delivered some of the most detailed information we have about the dark universe, including actual pictures of dark matter. No mean feat, since the stuff is invisible. On top of her academic achievements, Catherine is also committed to making science accessible to all, not least by taking an astronomy-themed comedy show to the Edinburgh Festival and beyond. Proof, if any were needed, that I should leave further attempts at humour to her. Professor Catherine Haymans, welcome to The Life Scientific. Oh, thank you very much, Jim. Thank you. So an astrophysics comedy act, how did that come about?

2:29Well, I have always loved talking about science to anyone and everyone who will listen. And in my early career, I went to a lot of science festivals and had a fantastic time. But I became sort of aware that I was preaching to the converted. And what I really want to do is change the misconceptions that people have about science. I mean, you'll know it, Jim, people tell you that science is boring or far too difficult for me. And unfortunately, if you're a girl, well, you know, don't worry, love, science is not for you. And I realised that if I wanted to really shift the dial on those misconceptions, I had to talk to people who wouldn't normally interact with scientists.

3:06So I could tell them, no, science is really creative. It's innovative. It's exciting. It's fun. It's the best career. and then I accidentally ended up doing stand-up in a pub during our very first meeting in the UK for the Vera Rubin Observatory, which I'm sure we'll come on to. We will do, yes. And I totally sucked at him, I was awful, but I did manage to get some laughs and, ah, the joy, the exhilaration. I mean, there's nothing better than making people laugh. And it just went from one thing to the next. My colleague, Joe Zuntz, he likes to call himself my academic husband. We research together, we share an office together and we are comedy partners.

3:43So our comedy show allows us to kind of parachute into like normal stand-up nights where people have no, they're not coming to see science, they're coming to laugh and two jolly professors get up on the stage and make them laugh and share a little bit of the joy of the universe. So, yeah. Because that's it, isn't it? You know, they're coming along to be entertained. It's not like they're coming along to a physics lecture. I mean, I'm sure not everyone appreciates the lighter side of a subject like dark matter. How easy is it to make physics funny? I have Joe to thank for all of that. He's the funny person.

4:13And I laugh as well. I mean, he's constantly changing the script mid-show and it's a lot of fun. Well, Catherine Haymans, let's move over to the darker side then. Your research is all about dark matter and dark energy. Can you spell out then what exactly they are and why they're important? Yeah, the big problem is we don't know what they are and that's why it's important. So we understand the physics of what makes up you and me and the Earth and the Moon and the Sun and stars. and we understand that incredibly well. But that makes up less than 5 % of our universe. And the rest, the other 95%, is dark.

4:47And we don't understand it. Like, the physics we teach cannot explain these dark entities and we've given them names. So there's something we've called dark matter. It's the strong kind of gravitational force in our universe. It glues everything together. It dictates when and where the galaxies form, but we don't know what it is. And then this other entity that makes about 70 % of the universe, We've called dark energy to describe a phenomenon that we've observed, that our universe is not only expanding, but that expansion is getting faster and faster, and it's accelerating, and we don't know why.

5:19And whatever happens, it's going to have to involve some sort of revolution in our understanding of physics, because each idea to explain these dark entities throws up a new way of thinking about our world around us, and so that's why it's so important. Yes, and you say these are deeply mysterious components of our universe, and yet you've actually managed to take pictures of dark matter. I said earlier that it's invisible. So how does that work? Yeah, so dark matter's not the greatest name. It doesn't absorb or emit like transparent matter would probably be a better description of it. And so the only way we can infer where it is is because of its gravitational effects on the things that we can see.

5:56Einstein's theory of general relativity tells us that mass curves space and time and that kind of warps our image of the distant universe. So what I've spent my entire career doing is mapping out large swathes of the night sky, collecting light from galaxies that are sort of 10 billion light years away and the light from those distant galaxies as it's travelled for all those billions of years through the universe towards our telescopes. Its path keeps getting bent and distorted each time it goes past a clump of dark matter that changes the path of the light and that very subtly distorts the shapes of those distant galaxies and that's what we're looking for, these very, very weak distortions in the images of very distant galaxies to work out where the dark matter is and how much of it.

6:41And the difference between dark energy smoothly, we believe, spread out throughout the universe, but the dark matter is clumped because it's gravitationally attracting. It sort of clumps together in blobby bits around the universe. Yeah, that's what my maps look like. They just look like a load of blobs. They're very beautiful to me. OK, so that's what dark matter looks like, blobs. Well, Catherine, I think anyone listening to you talk about astrophysics can hear your enthusiasm. And that love for science and maths started very young. You were born in 1978 in the market town of Hitchin, just north of London, where even at primary school, I gather, you were besotted by your maths books.

7:19Yes, I wonder how many people remember peak maths books. We had, you know, there were all of the different maths books and I just worked through them a lot faster than anyone else and asked if I could take it out at playtime and I was so, oh dear, I mean, what a sad child I was. But by the time I got to secondary store, I found my geek friends and, yeah, and all was well. And when did the interest in astronomy come in? For that, I have to thank a marvellous teacher. I mean, I'm sure everyone you've interviewed, Jim, will tell you about a marvellous teacher they had. Absolutely, yeah. So this is a shout-out to Mrs Elliot, if you're still out there.

7:52So she was my physics teacher and she spent a summer at NASA on a teacher training programme. And when she came back, she was just full of the joys of space. And at that time, I found the physics we were taught at school really quite dry. But it's the physics that we use to explain what's going out in the universe that makes me really passionate. Well, because of that passion, you decided to study astrophysics at university and you ended up going to Edinburgh. Now, tell me about that decision. Much to the disappointment of my school and possibly my parents as well, I turned down an offer to go to Cambridge because I had fallen in love with my wonderful still partner, Rory, who was Scottish.

8:36He'd come down south for a couple of years but wanted to return to Scotland and so was definitely going back to Edinburgh. And so I followed him to Edinburgh. Best decision I ever made because it meant I got to be taught at the Royal Observatory, which is still my home today. It was a very good decision. As you say, you and Rory are still together. You now have three children. But equally, Edinburgh itself had a huge influence on your career, not least because of a part-time job you had as a tour guide at the Royal Observatory there. Yeah, I had two jobs to fund my way through university. I was a barmaid and a tour guide at the Royal Observatory.

9:11And there was one very special night where those two jobs came together. So I'd been chatting to the people in the bar where I worked and they were like, we want to bring our grandkids up. And I was like, fine, yeah. So the Leith Community Centre came up and they ran me ragged around the Royal Observatory. They were fantastic. But there was one particular kid who just was too cool for this. It was all too boring and too sciencey for him. And that night, the heavens really aligned because the clouds cleared. So I got the telescopes out on the roof and lined it up on Saturn. And I got him to come and have a look first.

9:44I said, you know, look down there. What can you see? and he's like, that's a sticker. I was like, it's not a sticker. I was like, look, see that bright dot over there in the distance? See that light from that's coming down the telescope. It's focusing in the telescope and it's going up into your eye and what you're seeing there is the planet Saturn. And he looked at me and he went round the back of the telescope to check that I wasn't fobbing him off or something. And he came back and he looked down the eyepiece again and there was his paws and then he was like, it's no sticker. that's saturn that's saturn everyone and he was running around he was so excited and this change from this really sort of surly i'm too cool for this teenager to this joyous excitement it was just so excited about and got everyone to come and have a look how wonderful yeah and i just thought i want to give that experience to absolutely everyone i mean saturn is of course so lovely because of the rings it just doesn't look real does it when you look at it through a telescope During your final year at Edinburgh came another formative moment for you.

10:47You won an internship to work on the Anglo-Australian Telescope in New South Wales. Tell me about that. Oh, yeah, that was an amazing trip. So up until that point, I'd been quite interested in theoretical physics and I had this opportunity to go and work at the telescope. They pick three interns from across the globe each year. So off I headed, off to Australia. It was phenomenal. one of the jobs I had was working at the telescope in what we call the cascade so there's this metal cage underneath the telescope back in those days not everything was roboticized as it is now and we were taking a spectroscopy of galaxies so we were looking at the chemical composition of different galaxies but the spectrograph was sort of bolted on the the bottom of the telescope inside this cascade and my job was absolutely freezing so i looked like the michelin man jim absolutely so wrapped up massive puffer suit locked in this cage in pitch black every so often a nice australian voice would float in over the intercom saying could i uh move the dial again change the filters on the spectrograph and so i spent a long time underneath that telescope just thinking about the universe and and these wonderful galaxies and what could possibly be going on on these different worlds outside our own.

12:06And that moment of really being hands-on with collecting the data made me think, yes, I want to understand the physics that's associated with these objects, but I also want to collect the evidence to confront those different theories. So when I came back, I directed my PhD more towards observing than theory.

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13:00He's buried himself in a coffin for days, counted to 100 ,000 on camera, and even recreated squid games, all in an attempt to go viral on the internet. But it all started when he gave a homeless man$10 ,000. So is he a philanthropist reshaping capitalism? Or is he just the king of the attention economy? Find out on Good Bad Billionaire. Listen on BBC.com or wherever you get your podcasts. Well, as you say, Catherine Haymans, he went on to do a PhD at the University of Oxford, which is where you learnt about a technique called gravitational lensing that became a big part of your work. Could you just explain to me what that is?

13:36Gravitational lensing is the trick that we use to detect where the dark matter is. So the gravity of a big clump of matter, it doesn't have to be dark matter, it can be any type of matter, is curving spacetime which bends the light as it passes by. So just like the lenses in glasses that sort of focus the light for you, bending the light towards your eyeballs. You can kind of think of dark matter in space kind of like a gravitational telescope, bending and lensing the light and changing and distorting the images of those background galaxies. And that's the technique that we use to map out the dark matter.

14:11So whereas a lens refracts the light through the glass, here it's space itself that's bent and the light is just following that curvature of space. Exactly, yeah. It's the whole of space-time being curved by the gravitational pull of the dark matter. And for your PhD, Catherine, you essentially came up with a new method of gravitational lensing. How did that work? Yeah, so this was very early days in this particular area of research. Lots of people didn't believe that it could be done. So the distortions that we're trying to measure in the images of these background galaxies that's being created by the dark matter is absolutely tiny.

14:44And when the light goes through the atmosphere, through the telescope, onto your camera, you get sort of 10 % distortion. So how do you unpick what's happening out in space from what's happening here on Earth? And in very early days, lots of people were using different techniques. And my supervisor, Lance Miller, said, well, this is the way to do it properly. So we coded it up and tested it all out on some data that we were collecting at the time at the observatory in La Palma. And it was fabulous. But it was so slow. It was insanely slow. There was absolutely no way we could use this method to process all of our data.

15:18But by slow, you mean simply computers just weren't powerful enough to chug through it in a decent period of time. Exactly, yeah. But then, one of the clock forward, 10 years, the computers had caught up. And now that is the method that we use for all of the surveys that have worked up until now. And Lance has carried on perfecting it. And it's one of the key methods used for the new Euclid Space Telescope. Excellent stuff. Well, after your PhD, Catherine, you secured a fellowship at Germany's Max Planck Institute for Astronomy, where you were studying information from the Hubble Space Telescope.

15:51Now, how was that different from using Earth-based telescopes? It's like putting on a pair of spectacles. So we're catching this light that's been travelling for 10 billion years through the universe. And in the last sort of nanosecond or so, it gets muddled up by the atmosphere of your telescope and your camera. And if you can get above the atmosphere, suddenly your vision is so, so much clearer. And life is so much easier. So this was right after the fourth trip of the astronauts to the Hubble Space Telescope. and they had fitted it with a brand new camera, the advanced camera for surveys. And our team was the first team to take what we call a survey image.

16:28So not just one image of a patch of sky, but tiling them all together to create a survey, a big patch of sky. And very few people knew how to do gravitational lensing at the time. So I was employed to just analyse this Hubble data and make us a dark matter map and off we go. And it took me two years because it turned out that even though we didn't have the atmosphere to worry about, The Hubble Space Telescope still had its own oddities. And there were things that we learned about Hubble that nobody had thought about before because nobody had been trying to use it to such a degree of accuracy that you could measure these incredibly subtle distortions from the dark matter.

17:01But we got there in the end and it was such a beauty working with that Hubble data. And you say it took you two years, but at the end you could say, look, this is really solid data about dark matter. And having been at Oxford, then Germany, your next role took you further afield. You started a fellowship at the University of British Columbia in Vancouver. Your first project there involved more data from the Hubble telescope, this time focusing on a specific galactic supercluster. What was it that you found? Yeah, this is a massive supercluster. It's 2.6 billion light years away. Four dense clumps of clusters sort of all together.

17:40Just imagine a really, really dense region of the universe with thousands of galaxies in it. So galaxies have billions of stars. A cluster has lots of galaxies. A supercluster has lots of clusters. Yeah, thousands of galaxies. Wrap your head around that. And so we know that there are blue galaxies and red galaxies. Blue galaxies are young, red galaxies are old, but we don't really understand how they evolve, how they go from one to the other. So I mapped out the dark matter, and we found that, yeah, as the gravity of the dark matter pulled in the galaxies from the outskirts, they were changing and evolving.

18:09That environmental effect was changing their evolution. And this is still a work in progress, but that was a really wonderful example of how galaxies change. Yeah. Well, in 2008, you came back from Vancouver to the UK to take up a senior fellowship at your old stomping ground, University of Edinburgh, where you brought together an international team to carry out the largest survey of its kind. This is using what's called the Canada-France-Hawaii Telescope, based on the peak of Monokia, a mountain on Big Island, Hawaii. Absolutely, yeah. So the entire Canadian, French and Hawaiian communities pooled all of their resources on this amazing telescope to create a huge survey of the night sky.

18:52So it was 100 times bigger than anything I'd worked on with Hubble. And the teams were really struggling with this data set. The problem is when you scale up by 100, suddenly things that you thought weren't a problem before become a problem. You have to understand the camera to exquisite detail, exactly what was happening with the telescope and the atmosphere. And in the end, that old technique that we decided in my PhD was far, far too slow to ever be used on anything, amazingly now was working. At this point, computers were much more powerful. By this point, it was working really well, but it took five years.

19:26And as a team, we rewrote the rulebook on how to do this sort of analysis. And by the end, you revealed your findings, including very detailed images now of dark matter. Yeah, and once you get to big enough surveys, which is what we're getting to today, you can look at how the dark matter is evolving over time, which then gives you a whole new window into exploring theories about dark energy. I think listeners will also notice a trend here. More and more powerful telescopes mean better data, of course, but at the same time, increasingly difficult, more detailed analysis. So this is now we're at that stage of detail that you can not only study dark matter, but also the influence of dark energy.

20:04Exactly, yeah. And what happens when you can't find an even bigger telescope? Well, you use two telescopes at once, don't you? One on land and one in space, because that's your current project, isn't it? Yeah, that's my current. We have the Euclid Space Telescope that is up in space at the moment, mapping out the entire night sky that's not obscured by our own galaxy. And we're just weeks away from the very first data coming out from Rubin. The Vera Rubin Observatory, which is a ground-based observatory. This is one of the biggest telescopes in the world, combined with the biggest camera ever.

20:40It's got a Guinness World Record. And with that, we're going to be creating a movie of the universe, Jim. I'm so excited about this. Over 10 years, imaging the night sky on repeat, looking for things that go whoosh, flash, bang in the night, but at the same time building up an incredibly deep image of the universe. And there are pros and cons to both of these. Euclid up in space, it's a fantastic clear vision of the universe, but it's a small telescope, Vera Rubin Observatory, huge telescope, huge camera, but the atmosphere in the way. So the combination of these two surveys is really what we need to do because it's such a difficult question.

21:15And I should say, the naming of the Vera Rubin telescope is lovely, isn't it? Because Vera Rubin's the American astronomer who in the 1950s, 1960s, I guess, was the first person to give us really solid evidence that dark matter exists by looking at the way galaxies rotate. Yeah, she is one of my absolute heroes.

21:33Catherine Heymans:I was reading an article by her the other day, sadly, she's no longer with us, about when she was trying to map dark matter in the Andromeda galaxy. And back then, she had to hand steer the telescope. And she writes about how she spent all that time in this dark telescope dome, looking up at Andromeda, wondering who was looking back at her. And it just sort of took me back to that time in the Cascade, underneath the telescope, thinking exactly the same thing. Well, Catherine, alongside all your academic work, you were also finding time to follow your passion for science outreach, doing talks at schools and festivals, as you mentioned earlier.

22:12And it was around this time that you and your Edinburgh colleague, Joe Zunce, developed your comedy double act. You performed the Cabaret of Dangerous Ideas at the 2017 Edinburgh Festival and subsequently in other venues around the country. How did you enjoy that experience? Oh, it was absolutely petrifying, but also completely exhilarating. There is absolutely nothing more joyful than being able to make people laugh. Well, your efforts both in research and promoting science were clearly noticed because in 2021, you were made the 11th Astronomer Royal for Scotland. What's the most exciting thing you've done so far in the role?

22:47it's been an absolute joy my big project that i'm working on at the moment is called the scottish youth telescope network and we are busy installing telescopes in scotland's outdoor centers so these are places where primary schools visit they go for their residential weeks they go canoeing kayaking hill walking i mean it's a phenomenal experience for the kids and we're just adding on a telescope experience because these places are really remote dark sky locations perfect to have a telescope. And it's still early days. But so far, when the skies have cleared, the primary school children who have taken part have just found it as breathtaking as that teenager did back on the roof of the Royal Observatory when he first appreciated that he really was seeing the light of Saturn through the telescope.

23:34I mentioned in the introduction that you're the first woman to hold the title in its 200 year history. How big a deal is that for you? Yeah, I mean, gosh, it's 2025 and we've still got first female stories. Yes. I'm very honoured. I'm very pleased that the proportion of women in physics today is significantly better than when I was an undergraduate. My entire undergraduate years, I was not taught by a single woman. And things are a lot better on an academic level. The issue now is that girls are not choosing to take physics at school. So that's what we need to work on to really shift the dials on those cultural misconceptions, to talk to their parents when they're still little in comedy shows, to tell them that science is cool and really is for their little boy and their little girl.

24:22You know, it's for everyone. And I think that cultural dial is being shifted, albeit very, very slowly. We've been talking about this for decades and decades. Well, let's get back to you, Catherine. At the start of 2022, you were getting into your role as Astronomer Royal. You won the Royal Astronomical Society's Herschel Medal for Investigations of Outstanding Merit in Observational Astrophysics. Life was looking pretty good, but things took an unexpected turn in March of that year when you caught Covid badly. What happened? So my whole career, I've been on the academic hamster wheel and I've been the happiest hamster, getting faster and faster each year.