#426: Radio Interference & Tiny Universes: Listener Questions Explored

Hello again. This is Space Nuts Q and A where we talk astronomy and space science, although in this edition it's all about what the people want to know questions from our audience, and today we'll be talking about that old chestnut chestnut radio interference. Also, we've got a question that asks about the viability of a universe. How small is too small for a universe not to actually be viable? Dark matter and angular momentum and things like that, and water behavior. We know how it behaves on Earth, but what about other places? Is it different? It's all coming up on Space Nuts Q and a fifteen second gaidences in channel ten nine ignition Squench Space nuts or three two Space Nurse as and I report it. Bill Good, he's back again, Professor Fred. What's an astronomer? Ti thread? You can't keep me away? Andrew here, I am ready and willing as always excellent. All right, Well we might as well just dive right on in. We've got a few text questions today and one audio question. Our first question comes from Tobias. He said, gooday, Space Nuts you legends. We're legends? Fred? Is he saying? Is Tobias saying we're old? That's what it is legends. I'll take it, he says. Longtime listener literally have listened since day one too today. That's fantastic. Thank you, Tobias. I don't know how we kept you, but it's good we managed, he said. First time questioner. Though, I live in Marsfield in Sydney, right next to the CSIRO Astrophysics Lab where Wi Fi was invented. Wow. Has Professor Fred ever been to the site and maybe you know if you have, what did you do there? I've noticed that the radio telescope on the facility has not moved in a long time Daily Radio. Does radio astronomy still take place there or is it just a research facility? Wood interference from terrestrial radio interference make radio astronomy at this location a waste of time. Secondly, I've noticed in a lot of areas around Sydney and presumably in most towns and cities around the world, that the old school orange yellow high pressure sodium street lights are being replaced with much more efficient LED lights. Is Professor Fred able to say if this is making astronomical observations better or worse. If the same light was replaced from a high pressure sodium light to LED and they're putting them in the same putting out the same lumens in the color wavelength of light going to is the color wavelength of light going to make a difference to astronomical viewing or seeing. Guys are legends and your podcast is the best of all on the internet. Thank you so much, Tobias in last field. That's lovely, tombaias thank you. He doesn't listen to any others, but now it's nice to get some get some feedback, appreciate it and I'm very happy to have a go at Tobias his questions as well, of which there are, yeah, several, so let's go through them because I've got questions in front of me too. Have I ever been to the CSIRO Astrophysics Laboratory at mars Field? Well, actually I used to work there, not on the astrophysics laboratory, but in the same site, the headquarters of the what was the Angle Australian Observatory and then became the Australian Astronomical Observatory. That's where they were. That was our Sydney headquarters, laboratories, workshops, offices, and that's where the telescopes at Kuner Barbon were operated. From So my job was the astronomy in charge at Cone Barbon, but I spent a lot of time also at the mass Field site the radio telescopes there. There are some radio telescopes, and yes they are not state of the art any longer, so they're probably ornaments rather than being used. There might be some tests done on them, because you still often need to take tests images, or you know, just check out amplifiers and things of that sort from there. Yes, I should say the site is the home of CAST stands for CSIRO Astrophysics and Space Science, so that's the name of it. It used to be the Astrophysics Laboratory, but it's now casts sorry, Radiophysics Laboratory. It's now a CASS. So yes, the reason why we don't do frontline radio astronomy from there is exactly as Tobias says, too much radio interference, mobile phones, might waves, telly communications everything around there, spoiling the view of the sky. And then he moves on to something that's closer to my expertise, because I had a great deal to do with this when I was astronomery in charge. About the high pressure sodium lights, the orange yellow ones, they're actually slightly pinkisher high pressure the orange yellow. Are the low pressure ones pink. They are yellowish, but they move towards pink almost to the high pressure ones. They are being replaced by LEDs. Does it make observations better or worse? Well, okay, it's all about what it contributes to light pollution. And Tobias's question. If the same light was replaced from a high pressure sodium light to an LED light, and they're putting out the same lumens, that's the intensity of the light. Is the wavelength of color going to make a difference to the astronomical seeing And the answer is yes, because generally the LEDs are a much wider light. We describe it in terms of something called color temperature, and a color temperature of five five hundred degrees calvin is the same color as the sun as sunlight, and that's an intense white. So LEDs are for various reasons, they've tended to be this intense white. We see them in car headlights. It's actually quite damaging in the sense that that scatters through the atmosphere much more readily than the warmer colors of the sodium lights, which have a color temperature of a round about twenty seven hundred, so less than you know, kind of half what the some of the LEDs do, and that does make a difference. On the other hand, there is a positive for LEDs, which is that they are much more controllable. You can send the light down much more easily than you can with sodium lambs, so it swings and roundabouts. But great question. Yeah about yes indeed, And of course we see a lot of towns and cities that are taking on board the dark Sky project that you and money have been involved in, particularly money and trying to direct that light downwards. Certainly here we talk very recently about radio interference that's potentially going to affect the likes of the square kilometer array, but that's more to do with satellite coverage. But yeah, I suppose it's a bit sad but not surprising that those radio telescopes at Marsfield have been rendered useless by being right in the middle of Sydney where all those mobile phone towers and mobile phone signals are that pretty well kill it. But yeah, it's very exciting to buy us to hear from you and learn that you live next door to the place where Wi Fi was invented. I just wondered, do you get free Wi Fi? A sequence of that A bit of a sneaky overflow maybe, but yeah, that's lovely to hear from you after so very long. Wow, and thanks for the question. Let's move on to our next question. You recently had a question about black holes creating other big bangs. If we live in a multiverse, how small could a universe be to remain viable the size of galaxy cluster, a single galaxy, or even a single solar system. Thank you for all your awesome episodes from Jeffrey. Yeah, look, let's assume for a moment there are multiverses, and there's certainly evidence starting to build suggests that may be the case that certainly has not been written off. But how small is too small for a universe to be a viable universe? I love this question for you. Yes, it's a great question, and I don't know the answer, you know, so I think if you had a small you have a universe created within a big bang. This is basically Roger Penrose theory, and that might be the place to find answers to this, Jeffrey, if you feel like hunting it out on the web. Although everything that Penrose does tend to be highly mathematical, because that's what he is, is a mathematician with a Nobel Prize as well. So if you think of a big bang that spurns spawns another universe, it will be highly compressed as ours was at the time of the Big Bang. It was basically a singularity with density approaching infinity. And you know, everything matters space, everything compressed into a very small space. So I don't know the answer to the question whether Penrose type multiverse evolution would allow for different sized universes. I simply don't know the answer to that. I suspect not. I suspect universes tend to be not necessarily come in one size, but you know, tend to be big, rather than the kinds of things that I think Jeffrey is thinking of. It's a great question, though, and I'm sorry I can't give you a better answer than that. But yeah, maybe i'll I'll if I've got an idle moment, sometimes I'll have a look at some of the patternal stuff and see if there's anything in there about it. I can't imagine any other universe being as small as a solar system because if they came into existence like ours, they'd be ever expanding exam that's right. Yeah, they wouldn't be tiny at all. And yeah, so I don't think in the scheme of things that there'd be too many tiny universes, if any. It reminds me of a science fiction show I saw once about a human astronaut who ended up on this planet and discovered the aliens living there, and he befriended a couple of them and ended up being sort of captured, and he was taken to the town mayor and he was trying to explain what the universe was all about, and the mayor said, no, no, there's nothing beyond five hundred miles of our planet. That's it. That's as big as it is. They were very naive, but I thought, yeah, that's what popped into my head when I read Jeffrey's question, This is and what positive of mind? Sorry to interrupt, Andrew, That's okay. I think what Jeffrey is talking about is the tiny verse, isn't it. Ah, Yes, could be yes well to an ant yes anything anything, you know, a few centimeters from the ant hills. Probably the extremities of the universe over the horizons. That's exactly there's this space. Now it's Andrew Dunkley here with Professor Fred Watson. Okay, we've tacked awful space nuts. Okay, let's continue going through our questions. This question, I'm going to laugh at this because it comes from Rosie's husband. Hi, Bredon Andrews. Thanks for the podcast, the truly great. My wife Rosie and I have been listening since that episode. Now, in relation to dark matter, I was just wondering if, in relation to a gravity's mass, whether the curvature of lights for the gravitational lensing that a particular galaxy might produce would could be used to infer its mass also, and whether that, if anyone's done the sums, whether that correlates with the masses right for angular lamentum. That's to say, does the gravitational lensing support also support the dark matter gravitational interaction to your I hope you know what I'm talking about, Thanks very much. By thank you, Rosie's husband, I mean my mask confessed that one confuses me. I'm I'm not quite sure where he's coming from, but I hope you do for it. Yes, And the answers to the questions to Rosy's husband's questions are yes, yes, yes, and yes wow. So yeah. So what he's saying is, if you've got a galaxy, you can infer its mass from the way it's rotating. And that turns out that the mass that we find from that method is much greater than the mass that we can see, and that's why we infer the idea of dark matter. But what he says is, Okay, if there's light coming from a more distant galaxy behind it and it's bent by the gravitational attraction of the galaxy, which is what Einstein's theory says will happen, does the mass you measure from that tally with the mass that you measure from the rotation of the galaxy. And the answer is yes, And in fact it's more. It's a richer field of study than that, because we use the gravitational lensing effect of a galaxy exactly to measure the amount of dark matter in the galaxy. But also you can map the dark matter in a cluster of galaxies. So if you've got and we've got many many instances of this through space, you've got a cluster of galaxies, they are gravitationally massive, objects, and they distort the space around them. If you've got another cluster of galaxies behind, you see those distant galaxies that their light is distorted by the distortion of the cluster, the foreground cluster, the gravitational lensing of it. And you know, you know on average what those distant galaxies are going to look like. And so what you can do is you can say, Okay, this galaxy should look like this, but it's been gravitationally lensed by the foreground galaxy, and you can use that to map the distribution of matter in the foreground galaxy. You can you can actually map where the matter is and it's not where you see it, and that's because it's dark matter. Most of it is dark matter. One of my colleagues once described galaxies in clusters as now, what did he call it? Kills of dark beacons. The galaxies are beacons of light on hills of dark matter. And we know that because you can you can map the dark matter by this gravitational lensing technique exactly as Rosy's husband proposes. So he's right on the muddy with us. The answer is yes. So we use that technique a lot in astronomy, they well done. Rosey's husband who didn't give us his name. It's Rosey's name, but that's okay. Thank you for the question. We've got one more question to wrap up this episode, and this one comes from Cam, Hello, Andrew and Professor Fred. So. There's good evidence that Mars had sizeable bodies of water some three billion years ago. I was trying to imagine what it would be like to experience aquatic leisure activities in a lake or ocean on Mars back then. Aside from the hypothermia, I would imagine camp. How does water behave on a planet with only thirty eight percent of Earth's gravity? How does it flow and splash? What would waves look like, supposing there was an atmosphere and wind to generate them, or certainly got wind. What would swimming and diving feel like. I'm guessing I'd be more buoyant sailing in a boat? What would that be like? Could you do a belly flop from two hundred feet and survive? A longtime listener and Van in the podcast, Thank you Cam from the Blue Mountains lovely part of the world to camp, Although if you swim in the Blue Mountains you can probably tolerate it on Mars, I imagine, yeah. I think the way to imagine this is it's a great question, what, you know, if we could have been on Mars when it was warm and wet, and we threw a rock into the ocean or the lake, what would what would the water look like? I think it would be similar to what it is here on Earth, but in slow motion because you're disturbing a water surface and it's under reduced gravity, as Camp says, about third of the Earth's gravity. So the droplets of water will take will move more leisurely through space, if I can put it that way. They'll take longer to return back to the surface after they've been thrown up by a splash. So just think of it all as being like on Earth in slow motion when you're swimming. Your buoyancy would probably be the same because the density of water and the density of your body similar, but your you know, the motion with the water itself would be more leisurely. And what makes me say that is recalling the way astronauts behaved on the Moon, where you know, they they walked, when they jumped, they jumped, and some of them did in slow motion, and there's that famous footage of the witch astronauts. It was I think it was Apollo twelve dropping a hammer and a feather at the same time they took a leisure Oh yeah, Scott, it was the astronaut was his name was Scott. I can't think of his first name, but he's that wore the bull ofvar watch onto the moon because he's his NASA watch broke. That's yes, the beloever, that's why I know who. Yes, that's that's great. So so yes, So think of it as splashing around, but in slightly slower motion. I think that will be okay. Would does splash be bigger for it? Maybe? I'm not sure. Actually, you've got a rock that's just displacing the same amount of water, So what's you haven't got as magic gravity? So that's right, so you can probably, Yes, so you certainly send stuff up higher. That's certainly true. A belly flop from two hundred feet not sure about that. It's bead to ask. Yeah, I was going to say would you survive? You know, that's the most important part of the question. Could you survive a belly flop from two hundred two hundred feet if you're big enough probably I wouldn't began to try it half to see I wouldn't. I would. I've been reminded of movies these last couple of episodes when people have asked questions. There was I think it was either Mission to Mars or Red Planet. I think it's Red Planet where they are stranded on the Martian surface and they're trying to get to where their base was located because of the they landed in the wrong place and they have to spend the night in the open, and then the next morning they need to pee. Now, notwithstanding the fact that they needed to actually open this space suit to achieve this, it was noted that when they were peeing there was much more significant arc in the flow. They even mentioned it there you go, look at the arc in lo g Yes, but that will be good. On reflection, how did they actually achieve that with spacesuits on. I'm thinking that was just a little bit of creative license. Thanks Cam, great questions, And I suppose it draws attention to how water behaves in other places if there was But if it's liquid water, it all comes down to the composition of the size of the planet and the gravitational forces thereof so it could vary from place to place depending on the circumstances. I suppose the best way to answer it without actually going into detail. That's my thought. I think that's right too. All right, Cam, lovely to hear from you. Thanks for sending you a question in thanks to Rosie's husband Jeffrey and Tobias as well. Thanks for listening for so long. Really appreciate that. Don't forget to send us your questions via our website, spacenuts podcast dot com or space nuts dot io. You can do that via the AMA tab at the top. We can send text and audio questions, or the send us your questions on the right hand side for audio only. But don't forget to tell us who you are or where you're from, like Rosy's husband did. All greatly appreciated. Love love getting your questions and working our way through them. Thanks Fred, as always, it's great fun it is. As long as it stays that way, we'll do it again. Yes, indeed, Fred, what's an astronomer at large? And thanks to Hugh in the studio for fixing all our edits. I think he's got about two or three hundred of them in this episode to deal with good on you Hu and from me Andrew Dunkley, thanks for your company catcher on the very next episode of Space Nuts. Bye bye Nuts. You'll be to the Space Nuts podcast available at Apple Podcasts, Spotify, iHeartRadio, or your favorite podcast player. You can also stream on a man at kites dot com. This has been another quality podcast production from kites dot com.