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Search Sage Accountant today. In 10 meters, take a left at the pile of washing. Sorry, what? At the valley of toy dinosaurs, approach the kitchen with no room to cook. Turn right at the floor-drope. You've reached chaos. Recalculating. Suggest immediate course correction to IKEA, for fitted wardrobes, children's storage and cupboard organizers. Find your way back to Calm. Discover smart storage at IKEA Hammersmith now. IKEA, the wonderful everyday. Hello and welcome to another bonus episode of the Supermassive podcast from the Royal Astronomical Society. With me, science journalist Izzy Clark, the society's deputy director, Dr. Robert Massey, and astrophysicist Dr. Becky Smithers, the queen of black holes is back! We missed you! Oh, thank you, thank you. I'm so sorry that I couldn't come with you. Well, these amazing podcast recordings you've been doing over the past couple of months. You wanted to meet more astronauts without me. I'm so, so jealous. Yes, I forgot the cardboard cut out of you. I am sorry. Yeah, I just wanted to apologize for the listeners that I did miss that. For those who didn't know, we're just going to get a little bit sad for a moment, but everything is fine. But yeah, the reason I wasn't there was, unfortunately, I was diagnosed with early stage breast cancer a few months ago. So I've been going to treatment through surgery, ongoing, but I'm feeling good, no pain or anything like that. And yeah, back to work to distract myself and everything like that. So yeah, it's just a lot of waiting around, it turns out, but I'm doing good. Becky, I'm particularly grateful that I don't have to take any more black hole questions. Yeah, I've come back because Robert just begged me. He didn't want to take any of them. Becky, I'm messaging over, you know, while we were doing all these recordings and she's like, have they been as like, there are significantly less Taylor Swift references? Hey. And I miss them. OK, good. I'm not complaining. I need more. I'll try to get one in for you. OK, so obviously we've just had the Q&A. We had loads of black hole questions. So Becky, we've got more for you. So you haven't missed out too much. So let's start with this one from Sierra, who says, Yeah, it's a great way. I love brain farts. That's amazing. Yeah, it's a great way. We were wondering if a supermassive black hole at the centre of a galaxy would just disappear. Bucket straight out. Yeah. What would happen to the rest of the galaxy? Since they don't make up a lot of the mass of a galaxy, as Dr. Becky said in a previous episode. Good, someone's listening. All right. Would the thousands of planets and stars keep spinning because of the momentum orbiting nothing, or would everything fly away? Thank you so much for keeping up the monthly brain farts. You are welcome, Sierra and Maya. This is a great question. It's one I absolutely love because I think people think about, you know, galaxies with their supermassive black holes at the centre as being very similar to like the solar system with the planets and then the sun at the centre. And yeah, if you removed the sun from the solar system, right, the planets would just fly off in every direction because there'd be nothing there to keep them bound. But yeah, the sun is 99.99 something percent of the solar system in terms of its mass. So it really is the most dominant thing. Whereas the supermassive black hole in a galaxy is less than 0.1%. 0.01% usually is where the correlation tends to lie. And that does change with time. JDBST is helping us find some galaxies where the black hole is like 10% of the galaxy's mass, which is crazy. We don't quite understand that yet. But generally in the, you know, nearby universe, black holes make up less than a percent of their galaxy's mass in stars. So it's a really interesting sort of thought experiment to say, okay, what would happen if you removed the black hole? Because it's such a tiny, very dense, massive part of the galaxy. But overall, it doesn't have that, you know, big of an effect. And actually it turns out if you removed it, it wouldn't have an effect at all. The stars, the gas, everything on stable orbits on the center would carry on regardless. Which is a weird thing to wrap your head around. And the interesting thing is the reason that this happens is the reason that the galaxy is there, or any galaxy is there at all, and we're here at all to answer this question, is because of something called self-gravity. If self-gravity didn't exist, we would all just be one big accretion disk of gas around a black hole. One big like swirling disk of material of gas just trying to make its way down into the black hole. And when not that, stars, planets, everything have formed instead. And it's because, yes, okay, the pull of the black hole's gravity is very strong, but at a certain distance away from it, it's weakened enough, might still feel the pull, but it's weakened enough that the gravity between, say, two gas particles next to each other is stronger than the pull from the black hole. Which means that you can collapse a gas-cow down into a star, and planets can form around it rather than that star being shredded apart and being pulled in towards the black hole. So if you didn't have self-gravity, i.e. gravity being stronger in an object's self so it can hold together as a star, then we would just all be one big swirling disk of material around the black hole instead of an actual galaxy with planets and people living on this planet to ask this question in the first place. Ooh, okay, great, thank you. And Robert, Paul Whitmarsh asks, Dear Supermassive, how would the night sky appear to inhabitants of a planet with an elliptical galaxy like M87, where the star system is at the same relative distance from the core that the sun is from the centre of the Milky Way? Would the absence of a-class and earlier main-sequence stars cause the sky to be barren of stars, or would the higher density of cooler stars still give those inhabitants enough stars to make their constellations? Love the podcast, I'm wishing Dr Becky a speedy recovery. Thank you, Paul. Paul Whitmarsh, Luz Astronomy Society. Yeah, hi Paul, and as this is my guess, we know each other quite well from Lewis and East Sussex where we both live, and I hope your broken arm is getting better too. Everyone's in the wars. I know, and clearly he's got time to write questions like this. One, presumably one-armed. One-armed, typing, yeah. Sorry, Paul. It is a really good sort of head-scratching question. An interesting one, I mean, so elliptical galaxies, I mean, first of all, they have a lot less dust than spiral galaxies like the one we live in and far fewer younger stars. And if you want to think about when we'll end up in that situation ourselves, well, after the Milky Way has collided with Andromeda in about four and a half billion years, it will strip out a lot of the gas material, might cause a burst of star formation, but the aftermath might, oh, looking back is the key now. Do you think? Well, if I was going to put my real, okay, this is my research on it. You've got to do this. Andromeda is much bigger than the Milky Way. The mass ratio between Andromeda and the Milky Way, Andromeda is much bigger than the Milky Way. So you could argue that this might not be what's called a major merger. It's more of a minor merger. Minor merger. Even if it was a major merger anyway, there's a lot of reports now that says if you merge the other two spiral galaxies, yes, it will sort of at first destroy the spiral galaxy nature and become a big elliptical blob, but the gas will actually stick around and reform a disk afterwards and then start forming more stars. So it might not be the end of star formation. It might not be the end of star formation in the Milky Way, but still carry on because it's a very good point. And now I know. It's like if we were writing the discussion section of this paper, I feel like we'd have it. We'd have it. Yeah, this is very cool. Anyway, completely derailed. That's all right. No, no, it's good. It's good to know. And so elliptical galaxies anyway, regardless, they have many more stars that are old and red. And they tend to be fainter because the brighter stars, the ones that, you know, if you look at the Winter Sky constellation like Orion has got quite a few bright stars that with relatively short lives and fainter stars live a lot longer. So if you run time forward and you run out of material, then you end up with a galaxy that's got more and more red dwarfs as a proportion of its stellar content. So there wouldn't, if you were in that hypothetical position, you have a higher density of stars. It depends exactly where you are and what kind of galaxy it is. But you wouldn't have that kind of defined Milky Way in the sky because the shape of the galaxy is different. You know, you're in an ellipsoid rather than in a flat disk one. And you might be looking towards a better kind of defined or a better brighter galactic center because you haven't got as much dust there obscuring the view. So that's interesting in its own right and a dimmer view in other directions. And I think given how faint red dwarf stars are at some point when you run the clock forward, you're going to get to the point where these objects, you know, if you've got a galaxy that's made up of mostly red dwarf stars, we can't even see the nearest one to the sun, which is also the nearest star to the sun, Broxen and Centaurates in the southern hemisphere. It's a hundred times fainter than the eye can see, so you need a telescope to see it. So I think, yeah, constellations pretty much disappear. You know, if the density is a bit high, you might have a smattering of stars in the sky, but it wouldn't be anything like as nice of you as we enjoy from the Earth. So terrible, really. So, yeah, not a great view. Fascinating astrophysically, and you know, you can see towards the centre of these galaxies, see the black hole in the centre, all that stuff much more easily. But, yeah, it wouldn't be the kind of exciting view that we enjoy on Earth. Great question, Paul. And Becky, Tommy says, hello, I'm a long time listener and first time questioner from Vermont, USA. I have a question that's been in my mind about living inside a black hole. If our universe is inside a black hole, how are galaxies moving apart if everything that goes inside a black hole gets pulled towards its singularity? Even if it's theoretical that we are inside a black hole, wouldn't the expanding universe immediately disprove being inside a black hole? Or could that possibly be the end result of the big crunch and we will eventually meet our end inside this black hole? Cheers. I feel like I've said black hole so many times. I'm just like, it doesn't make any sense anymore. Welcome to my life. Yeah, good question, Tommy. I think you really hit the nail on the head there. Wouldn't the expanding universe immediately disprove it? Pretty much, yeah. I think what's interesting with this is that people gravitate toward this idea of the universe being inside a black hole. I don't just mean people in the general public. I mean, Ash visits this as well. We've seen a few papers come out that explore this idea because there's so many similarities to... We think about what a black hole is made up of. We've got what we think is called the singularity where all the matter is condensed into a tiny, tiny, infatestinely small, infinitely dense point in the very centre of this sort of sphere of unknown space where we don't get any light from, the edge of which is this horizon. So there's this horizon that we can't see over into the black hole. And then we think about the universe, right? And we think about looking out into the infinite space and there's this cosmic horizon where we don't get any light from it because the universe hasn't been around for long enough for the light to reach us yet at the speed that it's travelling at. And if we think about the expanding universe and we rewind time, we end up with this idea of the Big Bang Theory where all of time, space, matter, everything was condensed into an infinitely small, infinitely dense point that we know is a singularity. So people are like, well, that seems very similar to what we know of about a black hole, which is where people get this idea from. But despite that, there is a whole load of evidence to the contrary, right, including the fact that the universe is expanding, as you say. And there are some people that go, well, maybe white holes exist, which are like the opposite of black holes. And maybe that could explain how the universe is expanding. But it's one of those things where it's like, you know, it's a straw man argument, right, where it's just a house of cards just all waiting to tumble and fall because there's so many like assumptions that you have to get to from there. And this idea did crop up fairly recently. And I'm wondering, Tommy, why, whether that's why you've asked this question, but there was a paper that got quite a bit of coverage sort of in science media in the past few months, which was a paper that came out looking at the spin directions of galaxies seen with the James Webb Space Telescope. So it's about 250 of them that basically someone said, oh, two thirds of them all rotate. I think it was clockwise and a third of them anticlockwise or the other way around whichever way around it was. It doesn't matter if we flip ourselves to the side of the universe, it would have been the other way around anyway. So it's saying, oh, if there's this like, you know, sort of preference for the galaxies to spin one way or another, that suggests there's some overarching force that wants them to do that. So perhaps it could be the fact that we're in a spinning black hole and that's why, you know, they're spinning one way or the other. That was like 250 galaxies in the other universe. And when that, you know, when that went sort of like quite viral on sort of like, you know, sort of science media, I was like, well, hang on a minute, like a load of people have done this with galaxies in the local universe with like a million of them and found no difference, like that it was 5050. So I think I trust the study that had a million galaxies rather than 250 necessarily. Obviously that's the local universe, not the early universe and telescopes like Euclid, for example, are probably also going to probe this and that's going to be a, you know, a full sky survey. So we'll be able to test this again and, you know, in the earlier universe, not just the local universe. So, you know, never say never. But I think there's a lot of evidence to the contrary that we're inside a black hole in the universe. And yeah, one of them is definitely the expansion of the universe as well. Tommy, as you said. Amazing. Okay, thank you both. And keep the questions coming. It's at SupermassivePod on Instagram or email your questions to podcast. We'll try and cover them in a future episode. We'll be back in a few weeks time with an episode about major space weather events. You haven't heard of the Carrington event. Get ready because this is the one we're all scared of. Until then, everybody, happy stargazing. Hi Derek, Tara from Flash Designs here. Hope you well. Not sure if you've seen my emails from last month, but could you please pay my invoice? Thank you so much. Bye. Hi, it's Tara, Flash Designs. Did you get my last voicemail? I know you're busy, but please pay my invoice today, if possible. Hello again. It's Tara again. Politely nudging again. Still chasing unpaid invoices. Let's Sage Co-Pilot help do the chasing so you can get paid up to seven days faster. Search Sage Accountant today. Crisp, vibrant and bursting with citrus. Villamiria's New Zealand Sauvignon Blanc is the perfect wine, made to be enjoyed on every occasion. 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