Latest / Space Nuts: Astronomy Insights & Cosmic Discoveries / #426: Radio Interference & Tiny Universes: Listener Questions Explored

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#426: Radio Interference & Tiny Universes: Listener Questions Explored · Space Nuts: Astronomy Insights & Cosmic Discoveries

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