The Supermassive Podcast - BONUS - What Shape is Space?

Episode Date: August 12, 2025

Izzie Clarke is joined by Dr Robert Massey to tackle your questions on the shape of space, measuring gravitational waves and planet spotting. We also have another - another! - astronaut: Producer Richard chats to British ESA astronaut Rosemary Coogan about her background as an astrophysicist. Join The Supermassive Club for ad-free listening and share your questions, images and more. Or email them to [e-mail] or on Instagram @SupermassivePod.The Supermassive Podcast is a Boffin Media production. The producers are Izzie Clarke and Richard Hollingham. Hosted on Acast. See acast.com/privacy for more information.

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With me, science journalist, Izzy Clark, and as ever, Dr. Robert Massey, the deputy director of the Royal Astronomical Society, is here too. So after our astronaut special last time, we've got one more astronaut for you. We'll hear from British European Space Agency astronaut, Rosemary Kugan, who is also an astrophysicist. My goodness, they just never stop, do they? Astronauts. They're just such overachievers, and I will continually say that. But this is also time for us to catch up on the supermassive mailbox. So Robert, first up, we have an email from John Hickson. And I'm going to paraphrase his question, which is about the shape of the universe.

So, Robert, is it curved? Is it flat? What shape is space? I'm glad you paraphrase that, Izzy. The simple questions are always great, aren't they? John, the short answer is that we think it's flat. Now, this is not an easy concept in itself, as you have to imagine, universe that is shaped beyond the three dimensions of space or four of you include time and something that we don't experience that even if there is that curvature we wouldn't experience it on a local level right so it's if you're talking about very large scales

and i was reading around this and i thought well actually you know the analogy is given that if you think about or the a triangle on a flat piece of paper okay the angles add up to 180 degrees if you think back to your gccc maths course or o level maths course if you're old enough but if you curve that paper then the angle that some of the angles changes if you draw a triangle on a sphere for example it's more than 118 if it's negatively curved it's like a saddle shape then the total is less than 180 so in a positively curved universe in some kind of hypersphere then in theory light would eventually travel back more or less to its starting point so the idea is it would go round you know you've got this kind of closed universe but from what we can tell

it's flat to an error of 0.4%. And we measured it by using observatories like Plank, which were there to survey the cosmic microarray background and looked at the distribution of hot and cold spots on their sizes in that now, when I say hot and cold spots, you're talking tiny, tiny fluctuations in the 2.7 degrees above absolute zero, the background heat of the big bang. But looking at those, the indication is that the universe is flat the way they're distributed. So the only thing I'll add to this is that to complicate things, this is just the bit we can see what's going to. called the observable universe and although you know it's reasonable to think the bit beyond that the unobservable universe is probably the same we absolutely can't be sure because we're just

no way of knowing okay thanks robert and next mark in arnold in maryland USA has a question about ligo they say i'm amazed that ligo instruments measure fluctuations in space one piece i don't understand is how they can take an event and determine which direction it came from how far away it was and pretty much what caused it. Any way of determining distance normally takes two detectors to establish a line of position. So how does LIGO do it with one? Yeah, Mark, I'm amazed too. Ligo is just incredible. To remind people, LIGO is the laser interferometer gravitational wave observatory based in two sites in the US, one in Louisiana and one in Washington. There's already two detectors and each detector has two arms as well. So you haven't got a single detector.

in both cases and they're designed to detect gravitational waves which are ripples in space time that result from dramatic events like the merger of black holes you know imagine black holes are dramatic enough now imagine two of them merging together that's a big thing by the time these ripples reach the earth they cause the two four kilometer long arms of each ligo detector to stretch by about a thousandth the size of a proton so a tiny tiny shift that sets up a tiny change in the lasers that run along each arm which are designed to cancel each other out basically and if they if they shift then the cancellation isn't there you get a spot you get a bright signal and that's what's detected and then we know there's a gravitational wave coming through and actually it turns out ligo and supplemented by

observatories like vergo in italy and cagra in japan and it's good if they're distributed around the world have seen now more than 300 gravitational wave events and the first one was only detected in 2015 so it's an absolutely emerging science people try to do this for decades it's so cool and it's suddenly like it's really taking off isn't it it just like what you can do in that time is amazing amazing ambition and their you know their ambitions to put lisa in space and to do all this kind of thing in the next decade where we get finer and finer measurements a completely different way of understanding the universe and to estimate the direction of their origin what the astronomers working on the instruments do is they time the arrival of the waves so if it arrives

at one arm before the other then that gives you an indication of the direction in the sky if you compare the arrival times from multiple observatories, so the three observatories around the world, then there's a difference, you know, you're talking really about a fraction of a second in the arrival time difference, but it's enough to give a rough idea of what it is in the sky. It is definitely rough. It's a lot harder to pin it down to a particular galaxy, and that's only really been done once with an event in July 2017 when two neutron stars merged in quite a close galaxy, NGC 4993, 144 million light years away, so, you know, a huge distance. But by the standards of these events, some of which are, if you happen 10 billion years ago, so really a huge

expanse across the universe, relatively close by. And that one was pinpointed. The aim would be to try and do that a lot more to say, you know, gravitational wave event happens, look for some optical counterpart, like, you know, what is there, is there some bright flash that are all burst of radiation that results when the black holes merge, for example? Thanks Robert. And actually we did a whole episode on this back in February of 2023, which was called Getting Gravitational Wavy. And yes, I definitely named that episode. I can tell which ones are mine. So before our next astronomy question, I just wanted to thank Thomas in Denver, Colorado for his really considered email on NASA funding, which we talked about in our main June episode. And Thomas described what's going on as the single-minded mission to gut the USA of education and research. capabilities at all levels. Thank you so much for taking the time to message us, Thomas. And thank you to everyone else on Instagram as well. I know we've got quite a few messages on that one. Robert, is there any update? Yeah, it's still really tough. I mean, I can't

disagree with what you're saying, Thomas. It's absolutely terrible. But, you know, we're trying to help in the way that we can. It's not very easy on the other side of the Atlantic and it looks like interference and so on. But we wrote to the Royal Astronomical Society. We wrote to the president of the American Astronautical Society to offer our support, and we pointed out the damage the cuts would do to science, not just in the US, but globally, and as well as hurting relationships with, you know, US allies like the UK and European countries and so on. And the AAS did actually thank us for that, and they said they used the letter in their lobbying of Congress, so maybe that helped a tiny bit. The last I heard is that the relevant committees, they have this system there

that's quite different to the way budgets work in the UK, but the relevant committees in the House of Representatives and Senate are looking at ways to restore some of the budget. which is a good sign. It depends, I guess, how that argument develops, but we won't know for sure until the autumn. So, you know, it's still fingers crossed. I really hope it's on nothing like the scale that's been proposed because that would just be so terrible for, obviously, some of these people are friends and colleagues in the US, but also just, I think, for science globally, it sends exactly the wrong message. You know, we want something positive to be happening in science right now. Yeah, it's definitely something that people are talking about quite a lot

at the UK Space Conference. So, yeah, it would be interesting to see how that plays out, as you say. Okay, let's move on to another question. This one comes from Brian Ross from the Supermassive Club. And if you want to join for an ad-free version of the podcast or, you know, interact with fellow fans of the show, then you can do so over there. Brian writes, oh gosh, hi.

Okay. Brian writes, y'all rock. And yes, that's how one says it in the American. American South. I think we're just getting messages where I have to say, y'all, and it just sounds bad. So again, everyone, I am so sorry. He goes on to say, Dr. Becky explained how the data from JWST is too noisy to nail down specific chemicals in atmospheres of exoplanets. Is it just getting the time to observe many hours of a particular planet's atmosphere, or is there a physical limit of the telescope itself? What kind of fidelity can JWST offer if budgets and time were not an obstacle. Thanks y'all. Great question, Brian. Thank you. It is. A good question, Brian. And thank you for joining the club. And I think we interact with each other on Instagram from time to time. So good to hear from you. Robert, can you say a y'all? Can we, can I say your, well, give me a thanks, y'all. Thanks y'all. Okay, great. That's, oh my God, that's

quite good actually. Brian, we're massacring your accent. What could I say? Right. Anyway, thanks Brian for joining the club. It's brilliant. Anyway, the question. So like any telescope, JWST has got limits based on the sensitivity of its detectors and its optics. So it gathers infrared light at a pretty decent rate. It's got a six and a half metre mirror. And to give you some context, that detects light 10 times as quickly as a 2 metre one or a gathers 10 times as much. But there's still a limit. So if you want to see things that are 10 times as faint, you have to expose because of the way signal to noise work. you have to expose for 100 times as long and 100 times as faint means 10,000 times as long. So it eventually becomes impractical to get any more light into the system.

To give you an example with very deep sky surveys like jades, I think they'd be running exposure times of 130 hours, so five and a half days of gathering light. Now, the relevance here is that if you're looking at the light of a star coming through the atmosphere an exoplanet to reveal its spectrum, okay, so imagine this light's coming through in this star, this planet is passing in front of it, we're looking at, these sort of signals superimposed or these little absorption features in the spectrum of the planet atmosphere. Now, that is not easy. You're looking for things which are a tiny change in brightness and the smaller they are, the harder they are to detect. And so for some chemicals with weaker

signatures, it will make things very difficult indeed and just becomes impractical. You know, I guess you could try and build up exposures and signals over a year, but that's not really a good use of the telescope. Really, you've got to wait for something with a bigger mirror to go into space to achieve that, and that might be some time off. There's also the spectral resolution, so that's how much fine detail we see by wavelength in a spectrum. And imagine, I don't know, finer and finer shadings of colour and looking at features within that. And for Neerspec, which is the instrument used to study exoplanets with JWST, that's actually pretty good. It's got a resolution of 3,000. That's a good number. And I'm not sure that in itself.

is a big problem for picking out the chemical elements. I think it's much more about the fact these signals are just really quite faint and superimposed on something that's that's a lot brighter. So in an ideal world, we'd do it differently and we'd look at planets separate from the star, but most of the time that's not possible. There are a few exceptions, giant planets that are separate from the star. But if we want to look for Earthlight ones, it's a bit different. One thing to look forward to is the extremely large telescope starting operation towards the end of this decade scheduled for first light in 2029 and it'll be based down in Chile. And one of its science goals will be to do that to look at Earth-like planets directly.

And in the 2040s, this is looking forward a long way, I'm thinking, yeah, I'll be long retired by then. We can look for something called the Habitable World's Observatory, which is being discussed, and, you know, the tentative funding is coming in for that, the design studies, and so on. That's an optical telescope, or will be an optical telescope that has an 8-meter mirror in space. Blimey. And we'll have a mask to block out light of stars so that the idea would be you, block out the stars light with a coronagraph. Basically, that's just what the mask is. And then the planets there would appear to move around it.

And then we could, hopefully, if they're there, see nearby Earth-like planets directly. And then we could really analyze their atmospheres for chemistry and look for things like water and CO2 and free oxygen and all those things that might be signs of life. Yeah, it's amazing. And those coronagraphs are brilliant. So it's a bit like if you hold, if you wanted to see the, see a view or something and the sun's in the way and you hold up your thumb just to cover the sun, you can suddenly see a lot more, and that's sort of how that coronagraph works.

And that's exactly it. It's so good. Exactly. And the difference is that if you're on Earth and you've still got a bright sky around you. If you're in space, you haven't. So you block out the light of the star if you get this right. And then theoretically, at least, if the resolution of your telescope is right, you can see things around it.

You haven't got a bright sky around. You've just got the vacuum of space. So theoretically, that's a brilliant way to try and find these planets. And, you know, I don't know, I may well be lovely to. I will be longer at a time, but I'm absolutely sure. But it's something I'd really like to see. You know, imagine just finally, finally detecting Earth-like clients around others. But you'll still be doing this podcast.

Yeah, that might well be the case. Thanks, Robert. And thank you for everyone who sent in space questions. But before we go, we thought you'd like to hear from our fourth British European Space Agency astronaut Rosemary Kugan. She used two and a half years into her training for a mission to the International Space Station by 2030. And before Rosemary was selected as an astronaut, She was an astrophysicist, studying black holes and the evolutions of galaxies.

If Becky was here, we'd say, yeah, she can be in our gang. It's cool. So producer Richard Hollingham caught up with her at the UK Space Conference. As a scientist, I perhaps bring a different point of view than somebody coming from a very different background. And my colleagues have a really wide range of backgrounds. We have some scientists, some doctors, some people are coming from military backgrounds, just to name a few, engineers. So I think we all bring a different perspective. And perhaps as the scientist, I lean more towards kind of some of the problem-solving aspects of things and perhaps less operationally focus on people coming from those operational backgrounds.

So what we really get by working in these teams and learning together is sharing those experiences and all coming to that place where we work really nicely together and it's a fantastic dynamic. I wonder whether every astrophysicist secretly wants to be actually in space, in the thing you're studying? You know, I wonder that. And I have to say, I have a fair few astrophysicist friends who did apply also for the selection.

But I have some astrophysicist friends who just went, no, I don't fancy that. You know, and it actually is a very different, it is a very different job. It is very much not, I mean, I have a very much a deep fascination for space, and I think both being an astrophysicist and an astronaut really fills that box.

But it's not job. just looking out there anymore. It's actually very much looking back at Earth, kind of both in terms of the fact we are physically looking at the Earth when we're on the International Space Station, but also thinking about how science in space in all different topics, nothing to do with astronomy actually benefits our lives on Earth. So I actually feel as though there are two halves of the same thing, but actually not necessarily that overlapping. So I completely understand. And you know, that's the spice of life, isn't it? That everyone likes different things.

Does it give you a sense of perspective, I wonder, already? Because astronauts always talk about the overview effect of being out in space. I wonder whether you've already kind of got that, because you've studied things like black holes in distant galaxies. It's a really great question. And I'm really fascinated to see how the overview effect will feel. I've heard really powerful kind of anecdotes from colleagues about that. And I think you're absolutely right.

I think already taking a step back and looking at the Earth must be, you know, wow, okay, this is where we are. Look how tiny we are compared to this amazing planet. But I indeed like to zoom out from that even further. I mean, my background is studying galaxies billions and billions of light years away. And to think that, you know, the Earth is a dot within a dot within a dot within a galaxy within a universe. Yeah, it gives perhaps even further perspective. It's, yeah, fascinating. And ultimately, you know from studying the evolution of galaxies that ultimately we're all doomed.

Oh, I'm not sure that is the conclusion I came to in my thesis. But, yeah, I wouldn't say, I wouldn't say we are doomed at all. I think studying the history of the universe is utterly fascinating. You know, there are certainly extremely physical dynamic processes that are going on in galaxies, between galaxies. There are galaxies that are brought to life and galaxies that do evolve. and die quickly as we'd call them when they're no longer forming stars. But now I think we have a very bright future ahead of us. It's coming back to astronauts.

I mean, how do you see the role of being an astronaut now, compared to even 10 years ago or, you know, 20, 30 years ago? I think the role of an astronaut is certainly evolving. Perhaps, you know, 30 or so years ago, we were nearer the beginnings of really kind of those first steps of exploration, especially since the ISS has finished being assembled. We have now that very, very large laboratory for doing that science. Being really scientists in space as well as explorers is something which is becoming more and more prominent. Of course, now we're talking about going back to the moon and going back to Mars. it's also that there's going to be really both explorers and scientists, you know, we're kind of both as astronauts and very much facilitating the science from the ground.

But I also think perhaps the communication side of things is becoming more and more prominent, probably just because of the world we live in today where there are more ways to communicate, you know, this podcast, for example, all sorts of news outlets. And I think it really offers an opportunity and a platform to talk about, you know, why I think these things are interesting what we can learn from space and really encouraging people to find what they feel passionately about and perhaps in STEM, perhaps in space. So those two sides, but the communication side of it, I think is a massive part.

Issa Astronaut Rosemary Kugan. I think the astronaut alarm is probably going into overdrive by now. And you can hear a longer version of that interview, which includes more about her training in the July editions of the Space Boffice podcast, which Richard co-hosts. Do keep sending us your questions, your pictures, we read them all, we love them, so you can email podcast at r-as.ac.org,

or find us on Instagram at supermassive pod. We'll be back in a couple of weeks with another live recording from the UK's National Astronomy meeting where one of our guests was in the team that looked at the first pictures of a black hole. Until then, happy stargazing.