Galactic Ejections & Black Hole Explosions: Exploring Cosmic Queries

0:00Andrew Dunkley Hello again. This is Space Nuts, a Q and A

0:03 edition where we talk. Well, whatever you want to talk about. Basically, it's your show. This part of it, uh, every, uh, Monday we release these online. But, um. Yeah, uh, so what questions are we going to be dealing with today? Well, uh, we've got a question from Clark asking about the ejection of planets and stars. It's like being kicked out of a nightclub, really. Scott, uh, is asking about the death of black holes.

0:28 Rusty wants to know about the, uh. Uh, this is an old chestnut, this one. We've done it a few times, but I really like this question, so we'll, we'll do it. It's a what if about the sun and a story or a question about resources for getting into astronomy. If you want to be, uh, uh, you know, a beginner, we'll tell you all about it on this episode of space nuts. 15 seconds.

0:50Professor Fred Watson Guidance is internal. 10,

0:52 9, ignition sequence. Star space nuts. 5, 4, 3, 2. 1, 2, 3, 4, 5, 5, 4, 3, 2, 1.

1:01Andrew Dunkley Space nuts. Astronau Feels

1:04 good. And unravelling the unravel, ravelable is Professor Fred Watson Watson. I thought I'd try that. Didn't work. Astronomer at large.

1:14Professor Fred Watson Hello, Fred Watson. Uh, unravelling

1:16 the ravioli, is that, uh.

1:18Andrew Dunkley Yeah, that might be easier. Yeah, might be

1:21 easier to say too.

1:22Professor Fred Watson Yes.

1:23Andrew Dunkley Uh, how are you, Fred Watson?

1:24Professor Fred Watson Very well, thank you. Andrew. Good to see you

1:26 again as always. And, um, looking forward to hearing what our listeners have dished up for us today.

1:31Andrew Dunkley Yes, why don't we get straight into it? Um,

1:34 our first question comes from ORK Auckland, New Zealand. Beautiful city. If you've never been there and you're thinking of a holiday, that's not a bad choice. Love Auckland. Um, and get out on a boat and go and visit one of the islands where all the vineyards are. It's awesome. Anyway, Clark, uh, asks, um. Hi, guys. Love the podcast.

1:54 And I have a question.

1:54Professor Fred Watson Good.

1:55Andrew Dunkley Cause this is the Q and A edition.

1:56 Clark, your timing's perfect. Uh, can a sun or planet be ejected from a galaxy or is the gravity from the galaxy centre too strong for this? Uh, I've always wondered if a lonely star or planet could be sitting between us and, say, the Andromeda galaxy. Thanks. That comes from Clark. Uh, we've kind of talked about this before. We know there are rogue planets, we know there are stars that get bumped around. But, um, this is kind of within the galaxy. Could they be ejected beyond? I mean, let's do the whole spectrum of ejection. You know, you're not good enough. Get out.

2:35Professor Fred Watson Um, and in fact, uh, there's more of these

2:37 things than you might think. And the ones that we can detect are all stars. I'm not sure that there's been any detections of interstellar, sorry, intergalactic rogue planets or orphan planets. I think they're all stars. But yes, the space in between the galaxies, the intergalactic medium as it's called, uh, you kind of imagine it would be empty, at least empty of stars.

3:03 There's quite a lot of stuff in there actually. Um, one of my colleagues, Ken Freeman for a while was really interested in, uh, what are called extra galactic planetary nebulae. These are stars that have basically died, uh, shed their, uh, outer layers and formed what we call a planetary nebula. Nebula, nothing to do with planets. It's a name given to it by William Herschel because they look like planets, they're round. Um, so those are obviously things where a star has been ejected from a galaxy.

3:34 Uh, and indeed there are some between ourselves and the Andromeda galaxy, um, as Clark mentions. Uh, but, um, more to the point, we can measure the velocities of stars in our local neighbourhood and when you do that, there are some that are going fast enough that they will be ejected from the galaxy as a whole.

4:01 Uh, in other words, um, planets, sorry, stars that are disappearing. And the usual ejection method is probably, uh, a star that gets too close to the supermassive black hole in the middle of the galaxy gets this gigantic gravitational kick, uh, that hurls it out of the galaxy. Uh, uh, often if stars interact with one another, particularly when you've got binary stars, stars that come in pairs, um, something might perturb that, the fact that they're orbiting each other around the common centre of mass, um, and one might get booted out, the other might wind up going somewhere else. Uh, but that would not necessarily give you enough energy to leave the galaxy, uh, as a whole. And in that regard Clark's point is well made. Is the gravity

4:55 from the galaxy centre, uh, too strong for this for a star to be ejected from the galaxy? Um, and it's not, but it needs a kick by something as massive as a black hole to give you the impetus, the energy to leave the galaxy. Uh, so we essentially have used that, certainly with, um, what we call the RAVE survey. The Radial Velocity Experiment was carried out on, um, the UK Schmidt telescope in the early 2000s, finished it in 2013. The survey that I was the project manager for, uh, we measured the velocities of half a million Stars altogether. And one of the first papers that came out of um, um, that survey when we didn't have all that many stars that we'd measured their velocities for. But uh, it was a paper that was basically about

5:55 looking at stars that have been ejected from our Milky Way galaxy, uh, or are going to be ejected from the Milky Way galaxy. They've got enough speed to do that um, and work out what the escape velocity of the galaxy is. It sounds like picking yourself up by your own bootlaces but you can do it. Once you know the escape velocity of the galaxy you know its mass. So this was a way of weighing the galaxy which we did very early on in the rave survey. I think the numbers have changed slightly now because we've got far far more particularly from the Gaia ah survey uh, which was um, a spacecraft that was measuring um, very accurately the speeds of stars across the line of sight, not necessarily along

6:43 the line of sight. Anyway, the bottom line is to cut a short question, uh, a long answer to a short question shorter, the answer is yes Clark, you can uh, and we see them and we can measure them and we can actually get useful information from them.

6:58Andrew Dunkley M. Uh, the escape velocity of our galaxy

7:02 uh, at the centre is roughly 220 to 230 kilometres per second. Uh, an object would need an additional boost of about 317 to 330 kilometres a second in the direction of motion to completely break free of the galaxy's gravitational pull. That's pretty heavy stuff, isn't it?

7:23Professor Fred Watson Yeah, and that tallies with my recollection

7:25 uh, about um, in what we call the solar rays radius, the sun's position in the galaxy because the escape velocity varies depending on where you are in the galaxy.

7:37Andrew Dunkley By comparison, Earth's escape velocity is

7:39 only 11.2.

7:41Professor Fred Watson Correct. That's right. Um, but the

7:44 galaxy's escape velocity in the region of the sun is about 400 kilometres per second. Uh so yeah, it's because it's a bigger object.

7:53Andrew Dunkley Yeah, that's tough going.

7:57Professor Fred Watson Yep. But stars do it. We've got

7:59 something.

8:00Andrew Dunkley Oh they do. It prompts a question in my mind

8:02 that slipped out of my head but now it's jumped back in again. Uh, are there likely to be ejections as a consequence of the merger between the Milky Way and Andromeda galaxies? Something's going to get kicked out.

8:16Professor Fred Watson Yeah, I think whenever you have a

8:17Andrew Dunkley company merger someone gets the boot.

8:22Professor Fred Watson Um, yeah, it will be um, look, it'll

8:24 be kicked out uh city. I think when that happens there will be such high, um, levels of gravitational interactions between stars and stars, stars and giant molecular clouds and stars and black holes that we'll probably see, um, the resulting galaxy, which, as you know, will be called Milcomeda, uh, the Milky Way and the Andromeda galaxy combined. Milkomeda, uh, will probably eject a very large number of stars, many more than we see being ejected from the Milky Way.

8:58Andrew Dunkley Yeah. Ah, well, before I got into radio, I

9:00 was a banker, believe it or not, and I actually worked.

9:04Professor Fred Watson Yeah.

9:05Andrew Dunkley Yeah. And I,

9:08 I, I worked for a bank that merged with another bank. And it was kind of like Milkometer, because we had twice as many tellers, twice as many managers, twice as many examiners, twice as many, uh, general hands, um, all those, those banking positions that, uh, yeah, we had twice as many people, um, because, you know, they closed half the branches because you didn't need two branches of the same bank in the same street of every town and city in Australia. So, yeah, we eventually it created this conglomeration of people and there weren't enough jobs for them, and it got, yeah, it's part of the reason I got out and got into radio, because there wasn't much of a future for me there. So it's just how the universe works sometimes.

9:50 Indeed. All right, thank you, Clark. Um, that was a great question. Lots of fun to tear that one apart. Boom. Boom. Question, uh, two today comes, uh, from, um, Scott in Hobart, Tasmania. Hello. Fred Watson and Andrew have a question for you. I understand that Hawking radiation will cause black holes to eventually evaporate. I think I heard 10 to the 76 years. Uh, what I haven't heard described is what happens to the black hole once the mass falls below the threshold where light can escape. Will the loss of equilibrium between mass and light pressure result in an explosion? Perhaps you can talk us through the final process in the life cycle of a black hole. Thank you both for a terrific podcast. Thank you, Scott, for

10:35 the good wishes and the great question. Yeah, um, I've never thought about a black hole getting to the point where its gravity can't hold back the light anymore. What happens then?

10:48Professor Fred Watson Um, so actually,

10:51 uh, um, um, Scott. I beg your pardon? I'm trying to get my nose here. Yeah, Scott is right. Uh, there's an explosion and it's very violent. Uh, and sometimes it's got a name. It's called the Final burst, which is, uh, a bit modest really, for what kind of energies that they're talking about. Um, and so it comes about, and we've talked about this before, Andrew, A uh, black hole's temperature is inversely proportional to its mass.

11:29 So the more massive a black hole is, the cooler it is. And the ones we've talked about in the past have been very cold indeed, uh, just a few degrees above absolute zero. But as the mass gets less, uh, it gets hotter. And um, and so that produces a radiation from the black hole. And we're talking now about a time, yes, when it can no longer hang on to everything.

11:57 And you get this sort of runaway, uh, effect, like a runaway greenhouse effect, except it's not the same. But basically that runaway causes um, the explosion. Um, I mean the theory, you know, this is all theoretical of course, but the theory predicts that the temperature of a dying black hole right at the end of its life will increase to billions of degrees.

12:27 And in the final second the evaporation rate becomes so extreme that you get this enormous amount of energy that comes from uh, the dying black hole. Uh, and there are possible different end states. Um, and I guess the one, the most logical one is that it totally evaporates, so it becomes nothing. Uh, all the mass has gone in a flash of really high energy particles, probably gravitons as well as photons and other stuff.

13:04 It basically uh, just flashes out everything, uh, and once again leaves nothingness behind. There is one, uh, I mean we're talking now about theoretical stuff. Some others have suggested that it shrinks to something called uh, the Planck mass, uh, where quantum gravity effects become the dominant feature. Um, and essentially you get, and that sort of stops the evaporation, if I can put it that way. Um, so there's something gets left behind, a sort of quantum element. And then finally, um, Again, when you look at the details, uh, it's probably uh, another possibility rather than all these things happen as well. I think, uh, we're talking about separate cases here that may have different, different starting points.

14:09 I'm not sure, I'm not actually sure how uh, robust this theoretical stuff is as well. But some authors have suggested that you get gravitational shock waves as well. Basically when it gets to the end, uh, you get a shockwave as well as that explosion. Uh, and so what you might call trapped information, the stuff that Hawking argued about with another well known cosmologist, I can't remember who it was, uh, that trapped actually gets blown out into the universe because of a gravitational shockwave. All these things sound like, you know, using posh names for something dramatic that happened.

14:49 And I'm not sure how many of them are really very robust theories, but it seems to be the case that the likelihood is there will be a violent explosion at the end of the Hawking radiation period as um, uh, Scott says, you know, 10 to the 76 years. It's a huge number of years down the track.

15:09Andrew Dunkley Yes. A black hole doesn't go out quietly.

15:12Professor Fred Watson That's the bottom line.

15:13 I think that's the succinct way of expressing what I've just taken half an hour to say.

15:17Andrew Dunkley Yeah, that's fine, yeah.

15:21 It's our job to take half an hour to say something that takes and

15:24Professor Fred Watson it's your job to make it succinct. So that's

15:26 good. And you do it very well. Andrew, I have to say.

15:30Andrew Dunkley Oh, thank you Fred Watson. Uh, and thank uh,

15:33 you Scott for your question. Lovely to hear from you. This is Space Nuts, a Q and A edition with Professor Fred Watson Watson and Andrew Dun. Space Nuts. Uh, now Fred Watson, we have an audio question. This is an old chestnut, but I, I do like uh, these what if questions. This is Rusty.

15:53Professor Fred Watson Hey guys, this is Rusty Mac from

15:56 Brooklyn, New York. Uh, they say that the speed of light is the fastest thing known to man. And if the sun instantly disappeared, we would still have light for 8 minutes and 20 seconds because that's how long it takes for light to get from the sun to the Earth. So if the sun disappeared suddenly, would the Earth still be gravitationally locked to the solar centre? Or would Earth, uh, and all the other planets get flung off into interstellar space immediately or would there be a delay? And if that happened instantly, what would that mean? That gravity was faster than the speed of light and that gravity waves are actually the fastest thing in the universe. Mhm.

16:43Andrew Dunkley Okay, thank you Rusty and uh, hope all is

16:46 well in Brooklyn. I walked across the Brooklyn Bridge last year from Brooklyn into Manhattan and uh, it's a heck of a walk, which is worth doing if you're a tourist. Um, lovely, lovely place. Love the buildings around that part of the world. Yeah, gee, it's, it's a. Yeah, it's just so different to anything we have here really. Well, parts of Sydney probably resemble it, but nothing out where I live.

17:10 Um, the vanishing of the sun instantaneously. We have had that what if question once or twice before over the last ten years or so. Uh, but it's worth revisiting. I wouldn't like to think what could cause such a horrible thing to happen because I don't imagine that we would be around long to witness the long term ramifications.

17:32Professor Fred Watson No, that's right. Uh, it would be

17:35 cataclysmic. Um, but it's a good thought experiment to say, okay, what happens if the sun vanishes? And Andrew, you know the answer to this because we've talked about it before. So.

17:45Andrew Dunkley Well, we'd have 8

17:47 minutes and 20 seconds of sunlight and then we would be uh, plunged into eternal darkness and all the dogs and cats would start living together and um, everything would, would, would die. There'd be no photosynthesis, we'd uh, we'd not be able to produce food. We'd um, we'd, we'd, I, I, because we are not being held into a gravitational orbit around the, the sun, uh, everything would start to drift off into the Never, never uh, never to be heard from again. And, and we wouldn't last very long at all.

18:21Professor Fred Watson Um, that's certainly true.

18:22Andrew Dunkley And it would become cold. It would become

18:26 very cold.

18:27Professor Fred Watson Absolutely. Um, a bit of

18:30 radiation from the Earth itself because of the nuclear processes that are going on inside it. But they're pretty low level. We're not a star, we're a planet. Uh, and so yeah, you wouldn't be that warm. Um, but in answer to the question though, uh, actually you would still be attached to the sun for the 8 minutes and 20 seconds that it took gravitational waves, waves to reach our uh, planet. So uh, gravitational waves have been demonstrated a number of times and theoretically this was predicted by Einstein.

19:06 They travel at the speed of light. Gravitational waves travel at exactly the same speed. So that means that yes, gravitational waves are the fastest thing in the universe along with light and radio waves and all the rest of it. So um, there will be an 8 minute 20 second delay before we not only went dark, but also wandered off into the wide blue yonder. Uh, without the sun to hold us in orbit, we'd be zooming off at 30 kilometres per second in some straight line depending on it would be heading, depending on where the when, at what point in its orbit. The sun in the Earth's orbit, the sun disappeared. But it beliked a horrible thought. Slingshot effect. Yeah, it is a horrible thought. You should write a

19:46 science fiction story about this.

19:47Andrew Dunkley I think probably could. You know what I'm

19:50 doing at the moment? I'm writing a prequel to um.

19:52Professor Fred Watson Yeah, you said.

19:53Andrew Dunkley Yeah, the Human Epoch. Yeah.

19:56 I'm halfway through the first book. I'm trying to uh. Cause the hero of the Human Epoch trilogy is um, a fellow by the name of Gary Forrester. And I made him Canadian because the Canadians never get mentioned anywhere a lot of the time. And I thought they're such nice people, they certainly deserve a mention. So I made my hero Canadian. Could have made him Australian. Could have gone down the American road. But I think we've had enough American heroes in science fiction for the time being.

20:23 So I went Canada, and, um, I've decided to write his story leading up to the beginning of the human epoch, um, because I like the character so much, um, but I don't think he could even save us from, uh, from something as cataclysmic as the sun vanishing. I wonder what could cause that. And I don't think there's anything that could wipe it out instantly.

20:45 But maybe a black hole venturing into our vicinity would not be a good thing.

20:50Professor Fred Watson That's right. But if the black hole was black

20:53 hole worth its salt would be, uh, seized into orbit around that, uh, long before it gobbled up the sun. So we'd know about it.

21:02Andrew Dunkley Yes. We'd also get a lot heavier.

21:05 Maybe.

21:06Professor Fred Watson Indeed. Probably so. Yeah.

21:09Andrew Dunkley Yeah. All right. I, uh, think we covered

21:11 that. Uh, Rusty, thanks for the question. Great to hear from you. Love the accent. Okay, we've had a problem here.

21:19Professor Fred Watson This is Houston.

21:19Andrew Dunkley Say again, please. Houston, we've had a

21:22 problem. We've had a main beam. Roger, maineville. Okay, standby 13. We're looking at it. Stay smarts. Our final question today is, um, more of a. An educational query. I've, uh, recently gotten into astronomy. What are some of the resources for a beginner? Thanks. I, uh, haven't got a name. Just B, from Sydney. Thanks. Bea wants to get into astronomy, or has just started. Um, what would you recommend, Fred Watson, as somebody who's had a wonderful career in that exact science?

21:56Professor Fred Watson Well, I'd start with, um, there's this

21:59 really good podcast called spacenots that anybody wanting to get into astronomy could perhaps listen to as a resource. Um, ah, a lot depends on what you mean. Whether you want to be observing the sky, uh, or whether you're more interested in the stories that we often cover on space nuts about the way the galaxy behaves and whether stars can be ejected from galaxies and all of that sort of stuff. Um, and there's certainly plenty of material on the World Wide Web, uh, from reliable sources, um, including NASA, including Universe Today, an old friend of, uh, this podcast, including Ars Technico, another good friend, and phys.org, uh, they're all places where you can get good information that's P, P, H,

22:49 Y, S, not F, I, double Z. Um, so, uh, those are the sorts of things. Now, um, I also would point you if you're interested in learning your way around the sky to some of the sky apps that there are. There's several of them. Um, I have one on my phone that I'm a cheapskate, so I never went for the higher version, figuring that because I'm an astronomer I should know my way around the sky anyway. But sometimes when you can only see one object because of the cloud clouds, it's a good way of finding out what it is.

23:23 Um, lots of stuff like that. Um, hardware, of course, telescopes, binoculars. I'm always, uh, a, uh, fan of, in terms of astronomy, because even if you've got a site where you've got some light pollution and you're in Sydney B, so that, uh, it means you probably do have. It is. But you can still see, you get lovely views of the moon, uh, bright objects like the Orion Nebula.

23:50 Even in light polluted, you can see them. Uh, and the planets. Binoculars are not good enough to show up the rings of Saturn. Um, but a powerful pair of binoculars will show you some of the satellites of Jupiter and see the way they're moving, they look like little stars right next to Jupiter. Uh, and then if you want to get into telescopes, there are one or two companies which specialise in optics for astronomy.

24:15 Um, and they are for the most part, and certainly the one I'm thinking of, which is in Glebe, Sydney, uh, I won't give because that would be advertising, but, uh, they all know who I mean. Uh, it's, uh, not far from the fish market. There you go. Uh, that's a great place, uh, to get good advice on what you might need for what interests you and for what you can afford.

24:39 Uh, it's a place where, uh, the staff are not just there, uh, because it's a job. They're there because they're passionate about astronomy themselves and they want to enthuse, uh, other people in the same way that they are. So you get really good advice. And that's true, I think, with other people. Um, uh, astronomy optics centres around the country. There's several I can think of some in Melbourne and in Brisbane and elsewhere too.

25:06 Of course, then you're starting to spend big money and it really depends on what your resources are like and what your interests are. I still love, um, a planisphere, which is a piece of hardware, goes back at least 2,000 years. Uh, it's a little analogue computer, usually two cards, one with a hole in it, one with a star map on it and you can dial up the date and time on the edge and it gives you what the stars look like, of course, you can do the same thing online now. Um, and they're much more accurate. And of course they show the planets the online versions, which the old cardboard or plastic ones don't. But I've always been very fond of planispheres.

25:46Andrew Dunkley I'm just looking at some pictures of them

25:48 now. Yeah, I know what you're talking about.

25:53Professor Fred Watson Sometimes called a star wheel. Um, I've still

25:56 got the first one I ever bought when I was, I think 15. Uh, it's a Phillips planisphere. Uh, it's the 5 inch version. It was the small one, but it still works. Um, of course I see the sky from a different hemisphere now, so I've also got ones from the southern hemisphere too.

26:14Andrew Dunkley That's pretty cool. Another thing B that you

26:17 may want to consider, given our current level of technology is, um, something like I've got now, which is a smart telescope. Yeah. And, um, you know, on a clear night you can put this outside in your backyard and then sit in the comfort of your lounge room, especially if it's a cold night, and photograph, uh, things you can't see with the naked eye and would struggle to see with binoculars. Um, and keep the images that you've taken with it.

26:45 And um, it. A lot of them have built in educational information. They can tell you what you're looking at and explain who found it, when they found it, what it is, why it is. It's incredible technology. And they've built them so well that they actually have light pollution filters built into them. So even, um, the last few nights here, as we record, have been very, very m. Uh, bright nights with the moon. We had a full moon a few nights ago. Um, doesn't bother the smart telescopes. They just filter all that out and, um, you can still see a really good image.

27:26 Uh, and I've found a good trick. Um, when you get your image, I actually adjust the image as it is being, um, recorded by the system because it does stacking. Um, uh, I'll then put it through an AI, um, piece of AI software and say, I want you to just tidy this up. I'm paraphrasing. I tell it exactly what I want and it will enhance the image even further.

27:54 I showed you Fred Watson. I took a photo of the moon with it the other day and then I put it into ChatGPT and said, can you enhance this, sharpen it up, show me a bit more detail in the cratering. And it just went bang. And the image I got was, was stunning.

28:09Professor Fred Watson I thought it is, it's remarkable. Yeah,

28:12 it is, absolutely.

28:12Andrew Dunkley So that's something to consider. And it's a

28:15 really inexpensive way of actually getting into astronomy. Uh, I didn't mention the brand of mine, but they're all very, very popular. They're all very good. There are a whole bunch of them. Some of them are, um, in the hundreds of dollars. Some are in the thousands of dollars. It just depends what you want to spend. But for someone like me, who, who doesn't want to spend hours and hours outside in the dark in the cold because it gets damn cold out here in winter, um, that's the perfect solution.

28:46 So, yeah, might, um, be worth considering. That's just my piece of the pie.

28:52Professor Fred Watson Well, I'm glad you put that in as well

28:54 because that's a very important resource in today's day and age.

28:59Andrew Dunkley Indeed. And, uh, thank you

29:02 for the question, uh, Bea. And um, good luck with your future in astronomy. And that brings us to the end of the show. Fred Watson, thank you so much.

29:12Professor Fred Watson A, uh, great pleasure, Andrew. I'm glad we

29:14 made it without a hiccup. And, uh, great to have all those questions as well. Thought provoking as always.

29:20Andrew Dunkley And please send us more questions, uh,

29:23 because it's going to sound weird. This is time dilation at its absolute best. Um, Fred Watson and I will talk again next week, but we won't see each other for a month. I'll leave you to figure that one out. But yeah, go online to our website and, uh, send your questions through the Ask me Anything Anything tab. Uh, that is spacenutspodcast.com or spacenuts IO.

29:48 And Fred Watson, we'll see you real soon or in a month. Whichever comes second or first.

29:54Professor Fred Watson Whichever. Whichever. Is time dilated?

29:56 Yes.

29:57Andrew Dunkley I'll tell you about our travels when, when I

29:59 get back next week.

30:00Professor Fred Watson I'm looking forward. I'm looking forward to

30:02 hearing that. Yes. Thanks, Fred Watson.

30:05Andrew Dunkley We'll see you soon.

30:06Professor Fred Watson Cheers for now. Bye.

30:08Andrew Dunkley And, uh, thank you.

30:09Professor Fred Watson Thanks.

30:10Andrew Dunkley Yeah, thanks, Fred Watson.

30:11 Yeah, I appreciate it. It's gonna be a long haul. Uh, and thanks to Huw in the studio. Uh, you're gonna love this one, Fred Watson. Uh, Huw couldn't be with us today. He, ah, was ejected from our galaxy. Wait for it. Because he's lactose intolerant. Uh, you gotta think about it.

30:28Professor Fred Watson But I get it. I get it.

30:30Andrew Dunkley I like that one. And from me, Andrew Dunkley.

30:33 Thanks for your company. We'll see you on the next episode of Space Nuts. Bye. Bye. You've been listening to the Space Nuts Po. Available at Apple Podcasts, Spotify, iHeartRadio or your favourite podcast player. You can also stream on demand at bytes.

30:51Professor Fred Watson Com. This has been another quality podcast

30:54 production from Bytes. Com. Um.