Dark Matter Mysteries, Telescope Innovations & the Quest for Gravitons | SN602 Q&A

Hi there, thanks again for joining us. This is Space Nuts, a Q and A edition. This is where we answer audience questions. Well, we read them out and then we pretend we know what we're talking about, and most people fall for it. They might not fall for it today though, because we've got some really interesting questions about a matter of matter that we cannot see. Does it matter? We will find out questions come up about gravitons. We're also going to answer a question about space telescopes. Now that's right up, Fred Zali. He knows everything there is to know about space. Telee's written books about these things, so this is going to be a good question. And a question has come up about whether or not Olympus mons might make a good staging point for a space elevator. We will answer all of that on this episode of Space. Nuts fifteen, Channel ten nine ignition sequence Space Nuts or three two one Space Nurse. And I report it meels good and it feels good to have his one and only self, professor've Fred's on Astronomer at Large back in the chair. Hello Fred, Hello, hello here, all ready to go, fresh and. Well? Slept, yeah, sort tough weird. Night last night. I actually went to sleep fast, didn't I only woke up kind of once once, which is a new world record. And then I woke up at five eighteen am and that was it. My body went out that we're done binget up, go and watch something on television because I'm not you know, I don't want to go to sleep it ever again. So here we go. Who knows what will happened tonight. Sleep is a weird thing. We need it, and yet our bodies sometimes refused to comply. Yeah, yeah, it is. It's bizarre. It's a strange thing. Shall we answer some questions? I thought that was it. Well, I was just going to say, Fred, why can't I sleep? Let's answer some questions? Okay? Our first one comes from Ben. He says Ben here. It's good because I thought he was Ben too, the Aussie and Chicago with a few new questions. In your Last Question podcast, you mentioned about how eighty percent of matter is missing or not visible to us, and it made me think, how do we know or measure that amount in the first place. I know a lot of science is about measuring what we didn't find in results, but I'm curious about how they came to that eighty percent dark matter number. And secondly, for a smaller question, if you could pick the next large telescope to be launched, what would it be and why I'd personally love to see a new larger Hubble type telescope with all the advances we've applied to it that we've learned from the James Webb Space Telescope. Thanks again for the great podcast. Thank you, Ben. Great to hear from you. I hope all is well in Chicago, home of the Bears, Chicago Bears. Right, So it's a matter of matter, and he's saying, we know there's eighty percent of the universe made up of dark matter or thereabout. How do we know that? We actually the way that we get the you know, the accurate figures is quite interesting because it involves work of the kind that wasn't possible before astronomers started using fiber optics in their telescopes. And that's what I did. Was one of the pioneers of fiber optics in astronomy. The systems that we built back in the eighties the nineteen eighties have now evolved into Mars machines which are fully automated. The organization that I worked for has just delivered one to Chile, which will position two four hundred fibers in fifty seven seconds. And each one of those fibers can be aligned with a target star or galaxy, and that's the way you collect lots of information about very large numbers of galaxies and about their velocities, what we call their red shifts. So we'll get to that in a minute, because that's how we are so certain about these numbers, because of the ability to do that, to measure these very large numbers of galaxies what we call large girl surveys. But the story starts back in nineteen thirty three with Fritz Vicki, the man who famously called some of his colleagues not just bastards, they were spherical bustards. The reason for that was that they were bustards whichever way you looked at them. That's why call them spherical beasts. Astronomers love him, Yeah, I'm sure they do. I usually turned that down a bit and make it wrap bags. But for this show, I can reckon. I could quote him about him, it isn't quote. Therefore it's a quote. Yeah, part of it's a part of history. It is indeed part of history. But what he was doing was measuring cluster of galaxies actually in the Northern Hemisphere, consolation of Coma Baronesses, the Coma Cluster, a very rich cluster of galaxies, and he figured out that the he was measuring the motions of all the galaxies and when he looked at it, they're all going too fast for the gravity of what he could see to hold onto them. So if all that was there was what all he could see, then this cluster should have evaporated gazillions of years ago, and it hasn't. And he was the person who coined the term dark matter. He said, there's something there that we can't see. The astronomy basically ignored it because it was just too hard to get your head around. There's obviously something wrong, we don't know what it is. We'll go and do something else. And it wasn't until well, actually there was an Australian who in nineteen seventy Ken Freeman A and U still a good friend, He figured out that galaxies were rotating too fast for what was in them to hold them together, and that again was largely ignored that nineteen seventy result until VERA. Reuben basically did the same thing, but worked out that in order for galaxies to stay together and not fly apart as they rotate, they must all be enveloped in a sort of sphere or halo as we call it, of something we call dark matter, and that in nineteen seventy eight was the start of the modern era of dark matter. And so you can actually use those those measurements to make a crude estimate of what's missing. You know that you can say, use something called the virial theorem, which I've thought about for a long time, but that's what lets you weigh things by their motion. So you can weigh the dark matter by the motion of galaxies in a cluster, for example. You can then weigh what you can see because you know roughly how much stars weigh, and the stars are what you can see in the gas two, and then you can divide one by the other end you do get this sort of eighty ish percent. But the way that it's done today, as I've said, it involves these very large scale surveys of galaxies and their positions and velocities in you know, as much of the universe as you can see, very very large scale surveys involving millions of galaxies. And when you do that, you can make statistical deductions that tell you that the universe is made of something like seventy percent dark energy, about twenty percent dark matter, about five percent normal matter, most of which is hydrogen. So that comes from the large scale surveys, and it's because the positions of galaxies are actually determined by the gravitational forces. That they feel. And you know, that's the key to understanding dark matter and dark energy, to see how these forces stuck up. It's so hard to comprehend because when you say that five percent of the universe is made up of stars, planets, and gas, and you look out into space and see so many stars, so many other things, and yet you're only saying five percent of what is out there, it's it's mindblow, that's right. I mean some of that that figure of five percent is that when you look at it as a fraction of the mass and energy budget and energy and matter, you know they're interchangeable equals mc squared, and so it's when you do that something you realize that, yes, seventy percent of the mass energy budget of the universe is dark energy, twenty percent is dark matter, five percent thereabouts is his normal matter. But most of that normal matter is invisible to us because most of it's just cold hydrogen. The you know, the materials that make up the planets, in particular, the the you know, the normal elements that we see around us on Earth. There's a vanishingly small fraction of that that represents you know, their fraction within the universe. Yeah, all right, so that covers these eighty percent question. But he asks a question about what will be the next large telescope to be launched. What would you like it to be? Yeah, that's an interesting question. I mean, the thing that I'm looking forward to, and we'll see it online within the next probably two years, is the ELT, the extremely large telescope down in Chile that's going to be visible light telescope with a mirror thirty nine meters in diameter, and it will be able to observe because it's got this very sophisticated adaptive optic system that effectively puts it above the atmosphere. It is. It will have. Twenty times the resolution of the Hubble telescope. So if you've thought the Hubble images that you see have find detail in them, wait till you see what's going to come from the ELT, because it'll be twenty times better. And the reason why that's my favorite big telescope is that its cost has been almost since the beginning estimated at one point three billion euros and it still is. It's on budget and pretty well on time. And remember the James Web Telescope costs ten billion dollars to build, launch, and you know, and keep it going. As soon as you put things into space, their price tag goes up enormously, which is why I'm a big fan of ground based astronomy, especially when we now have sites like so Amazonas in northern Chile, which is where the ELT will be. Who's who's uh, you know, whose clarity and atmospheric stability you can hone with that adaptive opsic system that the telescope's got to be fitted with. So that's that's what I'm looking out for next. I don't think you need to launch anything else into space to get anywhere near what the ELT will do. Very exciting. Yeah, I heard they're going to have a visitors center at the el T, but the only thing on the menu will be BLT. So sorry had they do that joke? It just you know my brain doesn't let me stop something. No, I don't. Thank you Ben for the question. Great to hear from you. Let's talk about our sponsor, nored VPN. Now, if you care about your privacy online, maybe it's time to start thinking about a virtual private network, and nord VPN is by far the best you can get. It's one of the fastest and most trusted VPN services as well helping you protect your personal data, secure your Internet connection, and brows with peace of mind whether you're at home or on public Wi Fi. With just one click, NordVPN encrypture traffic hides your IP address, keeps your information safe from hackers, trackers and snoopers, and you can also access content from around the world without restrictions thanks to thousands of servers in over sixty countries. And as a listener of space Nuts, you get an exclusive deal at gnordvpn dot com slash space nuts huge savings plus an extra four months free when you sign up. It's simple, it's fast, it's secure, it works. Go to gnordvpn dot com slash space nuts and take control of your Internet experience today. Vpn dot com slash space nuts. Don't forget the code word space nuts and their thirty day money back guarantee of space nuts. I'm going to do a bit of a switcheroo here because we were already talking about telescopes, and we've got a question about telescopes, so we might just jump straight to that one. Hi, Fred and Andrew. Just wondering if Fred can shed some light pun fully intended on telescopes and the different types of light they can detect. I was recently thinking about how the James web Space telescope uses mirrors to observe infra red light but not visible light, while Hubble also uses mirrors for visible light yet can't really see infra red. That got me wondering how mirrors, detectors, and telescope design all come together or don't for different wavelengths. Could you please walk us through the various types of telescopes optical, infra red, radio all the way to gamma and explain what kinds of light they detect, how they do it, and why each telescope can only be used in certain ways. Absolutely loved the show. May Your Reign, May You Reign Supreme for many years to come. Cheese Ash, Thank you Ash, and he just wants to know everything you've ever written down a bed telescopes read. Yeah, there's a book on it. I recommend USh hunted out. It's called Stargaz's Other Life and Times of the Telescope. It's the first big, thick book that I wrote, and are still one of my favorites because even though it's slightly out of date. It opens by talking about what used to be called OWL, the overwhelmingly Large telescope, which was actually the precursor of the ELT. We were just talking about there. But when they were proposing OWL, which had an overwhelmingly large mirror of one hundred meters in diameter, and then they realized it also had an overwhelmingly large price tag, which is why it came down to thirty nine meters. And that's fine, because that's still. An extremely big telescope. Anyway. That's the plug over, that's the advert over. So basically, telescopes have sort of got the same ingredients no matter what they're observing, and that is something to gather at the radiation, and whether that's very short wavelength radiation like gamma rays or long wavelength radiation like radio waves, you've got something to gather the radiation and either focus it in some way or at least concentrate it, and then something. To detect it. And it's usually the. Detectors that are perhaps the most waveband critical, because you need different detectors, for example, to detect visible lights from the ones that you would use to detect infra red light. And again it depends on the infrared wavelength. So I guess starting right short wavelength end with gamma ray and X ray detectors. They are almost the same sort of technology as are used in medical imaging, but to focus them you've got to have very special technologies. My recollection of gamma ray telescopes and things might have changed a little bit here, but they made mirrors which were called grazing incidence mirrors, which looked more like a piece of origami than a reflector that you'd imagine, but they did focus the light to provide that thing. And then you go to ultraviolet. The hubble is sensitive to ultraviolet lights and that for that it needed a very precise mirror. And we all know that the mirror was made very precisely, but to the wrong prescription for reasons that we went time to go into. So once again, you know the detector is sensitive to ultraviolet radiation. In fact, they've got wide band quite wideband detectors. Hubble detect long wavelength ultraviolet whole of the visible and also the short wavelength infrared what we call the near infrared, and its mirror and detectors are capable of doing that. When you go up to the James Web, you're right, that's tuned for infrared light, and that means your tolerances on the accuracy of the mirror are slightly less because infrared light's got a longer wavelength, and you know, how accurate your mirror needs to be made is dependent on the wavelength. The longer the wavelength, the more relaxed you can be about the shape of the mirror. So Web telescope is slightly more relaxed, although still to very high tolerances. But the detectors are the thing that really render it not suitable for visible light. It's definitely got infrared sensitive detectors. It's also got a gold coating and that's so that rather than an aluminium or silver coating like a visible light telescope would have, it's got a gold coating because gold reflects in for red light better and then you get up to radio waves and you're talking about often dishes, and you know a dish is just a big mirror, but one that's as I said before, it doesn't have to be as accurate as the mirror on a visible light telescope because the wavelength is longer. And that's why we see these much bigger, bigger telescopes for radio waves. You get the. Same sensitivity to detail with a bigger dish than you do with visible light with a smaller dish. That's cause that sensitive to details proportional to the wavelength. But the detectors are quite different. In radio telescopes. They use often very sophisticated technologies where they're actually measuring the waveform itself, which you don't do with visible light what are called heterodyne receivers and things of that sort. So that's walking through the various types of telescopes, as you've suggested, is from another bit to the question how they do it? Well, I've explained that why each telescope can only be used in certain ways. Yeah, yeah, I guess the question he asks prompt a question in my mind or a suggestion that you really could not build a single telescope that could do absolutely everything you'd want to do on all spectrums. That's correct. There is a device which in fact is only used really in the microwave region. Of the spectrum. But it's called a bolometer, and a bolometer is something that is basically detect stuff, but it's insensitive to wavelengths. So in a sense, a bolometer, a perfect bilometer, will be able to detect all wavelengths. Now, the reality is you can't do that, but that's the notion behind a bilometer, and what it means is that for microwave astronomy, the bolometer gives you a very wide range of wavelengths to cover. So when you banning to build a telescope, do you have an objective in mind before you build it? Or do you build it and then think, well, what come. O you do? Is no, it's definitely the other way around. You you start off with the science case, what are the questions that we really think are the most urgent questions to answer? And you've got things like, you know, the nature of dark energy, the nature of dark matter, are there any living organisms anywhere else in the universe? All the questions that you and I talk about on the show are the ones that scientists are still intrigued by, and there are many others as well, the details of the way galaxies interact with the environments. What about all these young galaxies that seem to be more mature than we think they should be at you know, when the universe is only a couple hundred millionaiears or questions like that. They're all the ones that would go into the science case for a project. But there is always the background that you're going to find things out that you simply did not expect to find out, So that's usually added into the science case, the stuff that we just don't expect, serendipitous discovering. There's been so many of those made by the world's great telescopes. Yeah, thank you, Ash. That's a great question, and I could tell Fred was excited about it. I'm just going to go I'm going to go back to Ben's question about you know, what do you want the next big thing in telescopes to be. I've thought of one. I want to see the f WST in Fred Watson Space telescope. That's that's what I am said of that. Yeah, on the side of that, thank you, well, you're a pioneer in fiber optics. I mean, it makes sense to me that you should have one named after you. I always think the reason for my hairstyle is because I worked in fiber optics. Because the individual follicules got jealous of all these thin strands of material that I was playing with and they all just fell out. Yeah, they gave her. Yeah, so now we can't beat that. See later, friends, We're going somewhere else. Thanks Ash for the question. This is Space Nuts with Andrew Dunkley and Professor Fred Watson, a Q and A edition. Let's tell you about our sponsor in Cogny. Now, if you've been overwhelmed by a barrage of spam calls and emails and targeted ads robo calls, it's probably because they can find you online very very easily and just harvest your contact information. If you've ever felt like that, then the answer is in Cogny. What happens is data brokers collect and sell your details, leading to an endless array of spam and other potential risks. And if you want to get rid of that, in COGNI is the answer. It's your personal data removal assistant. It automatically sends removal requests to over two hundred and ten data brokers ensuring your information is taken down. You can even watch the progress of it through an online dashboard with weekly updates. You can track the cleansing of your digital footprint. Plus there's a thirty day money back guarantee, so it's risk free. It's called in Cogni, Take control of your online presence. Visit in Cogni dot com slash space nuts. And here's the kicker, sixty percent off if you use the code word space nuts. That's in Cogni dot com slash space nuts. Sixty percent off if you use the code word space nuts. Enjoy a peaceful online existence without digital disturbance. Open anguality, Babe, here the lambage space nuts. Next question comes from somebody else, Hi, Fred Andrew. Gravity is described by Einstein's theories as the bending of space time in the presence of massive objects. Great, Why then, does physics discuss the hype anthetical graviton as a force carrier for gravity? What would a graviton look like were we to discover it or discover its existence? And why is it needed at all in the context of Einstein's theory? Thanks keep up the good work. Love the show Russ from StarBridge in the UK Stourbridge it is. That's right, it's in the Midlands, StarBridge. I think I remember rightly. I mean, yes, it's a good question, and that's kind of hard to know how to how to start it because there's so much to say. So, yes, general relativity exactly as ros says, is that space time bends or there is says space time bends when you've got matter there. And all the evidence is that general relativity is absolutely on the money. It's you know, it meets predictions with such a higher level of accuracy that it's almost mind blowing. If I remember rightly, I think it's one part in tenth to the eighteen or something like that that it's been proven to work for. So that's great. But the physicists who look at the other end of the size scale, the ones who are interested in quantum mechanics and you know, particle physics subatomic particles, they say that all forces and here we're talking about gravity in the Newtonian sense that it's a force have have a particle that carries them. And so you know, we've got the photon for electromagnetic force, we've got the various force carriers for the strong and weak nuclear forces, and we've also got now the Higgs field, the Higgs boson. So what they're saying is that because gravity works that way, there should be a boson that carries gravity, and that's the idea of a hypothetical graviton. And my suspicion as to how that links with relativity comes from the description of the Higgs boson that I think we might have talked about a few weeks ago. So the Higgs boson is I think somebody asked about, you know, how do you reconcile the Higgs boson with something that gives all the other forces their mass, because that's what the boson does. And the bottom line is that what you're really talking about is the Higgs field, which is something like they usually talk about syrup or molasses, and as the particles move through it, they get resistance because they're, you know, because they're in this sticky stuff, and that gives them the effect of mass. It's not an analogy that thrills me, I have to say, but it kind of gets the idea. And the only time the Higgs boson itself appears is when you've got something a collision between particles. So the Higgs field is the main thing. But if you collide particles together, you get this thing that emerges from the Higgs field, which is called the Higgs boson, and that can be measured, which it was in twenty twelve. And my guess is that the graviton would be something like it. It would be a boson, It would emerge from the gravity field, and maybe would emerge when there were collisions in particle accelerators, but we have no evidence for it yet. So I think, you know, Russ, I think that's the bottom line, that, like the search for the Higgs boson, one day, the Higgs search for the graviton will basically cough up the goods and and well we'll understand it, perhaps in a similar way to the way we understand the Higgs boson. That you need to actively create a boson from the Higgs field. So maybe you need to create a graviton from the gravity field, which we're used to talking about. And some kind of particle to account for dark matter, and so well that's. Right, yes, yeah, the dark matter would probably be a fermi on, a thing that you know is a matter particle rather than a forced particle. Okay, gotcha, fair enough, all right, So where does a light particle fit in that? That's the photon, yes, gravitation, it's the electromagnetic particle. That's probably the best understood of the sub atomic particles because. We use it all the time. We're using it as we speak. Ah, it's very it's very handy. That's very handy. I've found it quite useful for reason it could. You probably find the strong and we nuclear force is quite useful as well, because they stop you falling to bits. That's a good one. I keep that in mind. Yeah, I think that's even more useful than photop Really, the problem with all of this spread is none of it gives me anything to work with to improve my golf game. So yeah, well you've got to start with the notion that five irons dot float and once you've got bus that step, then. You're getting some book plugs in today. That's one for you. Thank you very much, thank you, russ. I hope we covered that. I think we did, not sure, but anyway, it's a work in progress. We'll call it that. Our final question today comes from Robert. He said, Hi, my friends down under, I live in Arcerreri, Iceland, and I'm very much looking forward to the eclipses this year in the western part of Iceland. However, your recent fabulous show regarding Olympus on Mars, would this make a perfect candidate for a space elevator. That comes from Robert. Hello Robert, thanks for sending your question in our carea. You've been there, I have, yes. I sent you some photographs so you could see what it's like. We should put them up on the website. We could post them on in the space nets podcast group. That nice nice one of the main street Money and me in the main street in Aker area. We were there at this time last year, actually, Robert, so I'm sorry I didn't know you then, else we'd have looked you up. But we had a great time there. It was part of our Iceland tour which was not the best for weather, so we didn't see any Roory, but certainly experienced some really fabulous landscapes up in the northwest of Iceland. It was the first our first visit up to the northwest. We spent a lot of time in the south on previous trips. But yeah, Akai is such a stunning place, beautiful scenery, They. Love the cathedrals, don't they in Iceland churches you, they're amazing. The one, the one we saw in Reguvi just bleue my mind. That's right, that's that's the classic one. That is such an elegant building. And indeed there's church in that curre area is lovely as well. It is. Yeah, well you've got a photo of that one. Yeah, I'll post that to it. What was that question again? Oh? Yeah, as a good platform for a space elevator. Yes, there's a kind of problem because to make a space elevator stable, it has to start off from a point on the equator of whatever world you're trying to get up into space. Fright, and Olympus Mons, i'm told, is at latitude eighteen degrees north. In fact, it's eighteen degrees thirty nine minutes north, which is not the equator of Mars. So you'd have problems with it. It would need to stretch and shrink and I think would probably shake itself to pieces. So I think you've got to have the equator. So that's a bit sad because Olympus Mods, as Robert is hinting at, is, you know, it's high enough that you kind of already already held. Well you're already yeah, you're already on the way of your space elevator. So a nice idea, very nice idea, but I don't think it would work. That's a pity. Well, I suspect that the space elevator concepts probably not even going to happen. It just sounds like it's too expensive, too hard, and there are easy ways to do things. Yeah, well that's right. Reusable boosters is the way to do it, and as we talked about in the last show, that's now basically the normal way of getting into space. Very much so, Robert, great to hear from you. Enjoy those eclipses later this year. Yeah, that very exciting in Iceland. If you can get there, it be a lot of fun too. So Robert, hopefully we answered your question was an easy one, as it turns out, and that brings us to an end. Don't forget. If you've got questions for us, please send them in. We're actually quite desperately short of questions, so send them to us via our website space nuts podcast dot comspacenuts dot io, or just do a search for space Nuts Podcast on your favorite search engine. Click on the AMA button that is, ask me anything and send your text and audio questions in with your name and location. We would really love to hear from you. Fred. We're all done. Thank you so much. It was good fun today. It's been great. It's never fun any other time, but it was good fun today. I love connecting with our listeners, especially when they're in places like our Cary. Yeah. Yeah, what an amazing place. See you soon, Fred Chess for no. Professor Fredwart's an astronomer at large part of the team here a Space Nuts and thanks to here in the studio works really hard, but he couldn't be with us today. He got on a space elevator and he thought he'd be back in time, but some kid pushed all the buttons, so he was very angry. Anyway, he sent me a text and from me Andrew Dunkley, thanks for your company. We'll catch you on the next episode of Space Nuts. Bye bye. You'll be listening to the Space Nuts podcast available at Apple Podcasts, Spotify, iHeartRadio, or your favorite podcast player. You can also stream on demand at bytes dot com. This has been another quality podcast production from nights dot com.