Supermassive Black Holes, Voyager's Journey & Gravitational Waves Explained | Q&A

Hello again, thanks for joining us on Space Nuts, where we talk astronomy and space and science all at the same time. This is a Q and A episode. My name is Andrew Dunctor, your host. Great to have your company. Coming up audience questions. We're going to answer a question from Martin about super massive black holes. Ben has also got a question about black holes and gravitational waves. And the Favorite train driver is on about a voyager one, and Judd has some thought experiments for us. We'll check it all out on this episode of Space. Nuts fifteen, Channel ten nine Ignition Siquench. Space Nuts Guy or three two one Space Nuts. As when I reported Neil's good. And back to unravel, unpack and solve all of that is Professor Fred Watson, Astronomer at Large. Hello Fred, Hello Andrew, very good to see you. Good to see you too. I've still got my crochie voice. In fact, I've been so unwell. I'm still wearing the same clothes as I was last week. Well there you go, funnily enough, so am I? Yeah? Well what a coincidence? Shall we get down to business? Why not? All right to do so? Yeah, Now we've got some text and audio questions we'll go text first today and forgive my rather unreliable voice as I work my way through this. Hi Fred and Andrew. It's Martin here from Heswall on the We're all in Merseyside. I posted a question before and Fred mentioned that he knew Barnston, which is just a pleasant walk over the fields from here. I have a question about your favorite topic, black hole. I thought it was going to be golf black holes. I'm interested specifically in the process of their formation, and more particularly in super massive black holes. The mechanism for the creation of stellar mass black holes seems to be well understood, but I find it hard to believe that this can be the same way that super massive black holes in the early universe were formed. I've read that the gravitational instability theory posits that black holes can be formed directly when a massive cloud of matter collapses under its own gravity. Why is it not possible that there can be two processes at work depending on the size. For me, part of the evidence in supporting in support of invoking gravitational instability is the lack of evidence for the existence of intermediate mass black holes. What are the arguments against this theory as it does seem to be that widely It doesn't seem to be that widely accepted. If black holes are created in two completely different ways, what effect would this have on their properties? For instance, charge, spin, etc. I really enjoy listening to the show. It helps me keep up to date with the world of science, space and stuff. That's our slogan. Ha, well done, well done, Martin, that's our slogan. Yeah. Look, that's a really good question. And we only talked in the last episode about the different theories about how black holes are formed and the possible discovery of primordial black holes. So if you haven't heard that episode, wind back because it's worth listening to that story. But yeah, it brings up an interesting point. How can it be the same process for a super massive black hole versus another one, a smaller one. Yeah? So, I mean Martin's hit on one of the key questions at the moment in astrophysics and cosmology. So he's right up to date there, sure is. Because this idea of the super massive black holes in the early universe, for directly as a direct result of a cloud of gas collapsing without having to go through the mechanisms forming a star and then the star is basically exploding to form a black hole. That's quite new, and that might be why, as Martin says, it's not yet sort of considered to be mainstream, but it is very much an up and coming idea and theory that answers the criticism that the conventional theory has, and that is, conventionally, scientists have assumed that super massive black holes are created over long periods of time by the accretion of material, So we know how a stellar mass black hole is formed exactly as Martin mentioned. We understand that a massive star explodes at the end of its life when the fuel balance runs out. The outer layers are shed off and a super and over remnant and the center, basically the central core, collapses to be the black hole, which is a point with zero dimensions, a point where density is infinite, so that the conventional method says you start off with lots of those in a galaxy and they eventually accrete to form a bigger object, mixing with stuff that's sucked in on the accretion disc as well. That might include a few odd black holes dropping in to form eventually a super massive black hole. But the problem has been how do you manage to do that in less than a couple one hundred million years, which is you know where the earliest super massive black holes are after the Big Bang. We know about those because we can we measure them by look at using the James Webb space telescope. It's measured I think several objects within maybe two hundred and fifty million years after the Big Bang. In other words, we're looking back almost thirteen point eight billion years thirteen point six or something like that. How did they form so quickly? If that's the mechanism, and that's why this alternative mechanism of direct collapse from an interstellar from a not interstellar because there were no stars then, but from a primordial gas cloud might have occurred. And as I understand it, the idea of primordial black holes postulated, this is what we talked about last week or the last episode, postulated by Stephen Hawking in visage that there would be a very very wide range of masses of black holes, ranging from things less than the mass of the Sun. As we reported in the last episode. We think we've found one of those now to a supermassive black holes. I think that is all within the purview of Hawking's theory of primordial black holes. And so the question, you know, maybe the fact that we're finding the supermassive black holes too early in the universe might to have been formed by stuff coming together, might be a support for the Hawking theory that maybe some of these were actually formed immediately after the Big Bang. Wow, wouldn't that be interesting? And there was something about something that Martin mentioned about intermediate. Yeah, he said, for me, part of the evidence in support of invoking gravitational instability is the lack of evidence for the existence of intermediate mass black holes, although they're the ones we were talking about recently. That we now have discovered, have we not, Yes, but there's still normally there still seem to be yes, much error than the super massive black holes or the stellar mass black holes which exist in profusion, intermediate mass black holes have been quite hard to find. Up. Yeah, I mean, you know, what Martin says is right, that might point to the idea of gravitational instability. In other words, sort of primordial type black holes as being the formation that might point to that. And so I don't think there's an issue there. But yes, his final question, if black holes are created in two completely different ways. What effect would that have on their properties? For example, for instance, charge, spin, et cetera. Now, in fact, the only properties of a black hole that you can observe are the charge in the spin as well as the mass, and that that's because of something that you and I might have mentioned before. Andrew something called the no hair theorem, which I'm very fond of, if you can guess, and no hair theorem basically says that there's you know, there's virtually nothing of the black hole's characteristics that you can see from the outside. It's like suggesting a baldness of the of the black hole the event horizon. It doesn't give much away. Charge and spin are I think, I think only the only two apart from mass. Now I don't know the answer to that. Would there be any difference in those properties for two different methods of black hole formation. Thanks a really good question, and it's something that I probably should have a look at and see if I can find out. Yeah, I thought i'd look up no hair theorem to see what happened, and I didn't get an ad for a hair pill. It actually took me. It actually took me to the to the to the no hair theorrem the no hair theorem a bit of black holes. Yeah, so they go the internet actually worked. Yes, nice change, nice change, and a nice question, Martin. Thanks for sending that to us. Hopefully that helped you sort a few things out. But yeah, there's still a lot of theory around black holes yet to be proven. But we're chipping away at it. We are chipping away at it. Not me personally. I leave that to other people who are more astute. Thanks for sending it in. Our next question comes from our favorite train driver. His name is Andy. Train driver. Here, just a question for you on Voyager one. I know that he's currently traveling about thirty eight thousand miles per hour, and it's very low on fuel, and the fuel is used for the thrusters to point in the Santana's back to Earth. And I know that space is not empty. There's particles and space dust. So, because he've got such a long journey before he reaches anything significant, would the particles in space slow it enough to bring it to a halt, Because as far as I'm aware, it's got about forty thousand years before it reaches something significant. So is that a long enough time? Would you say to maybe not bring it to a halt, but to slow it significantly that it really does increase that timescale. Sorry if that doesn't make much sense. Thanks for your podcast, guys, really enjoy it. Speak to you soon. Bye. Thank you, Andy, Hope, Aul as well on your daily commute. Although you're the driver, so you just drag everyone else around. What a great job, right, okay? Voyager one thirty eight thousand miles an hour. Is there enough material to ultimately stop it because it's going to run into a few things here and there. Possibly, But I would question the spread of the dust when you get out into those interstellar places. The amount of material fins out significantly, doesn't it? Yeah, very much. So there is still you know, there are still atoms there or nucleari probably part of sub atomic particles. But it's not. It's not enough to significantly slow the spacecraft. It's you know, you're basically, to all intents and purposes, it's moving through a vacuum. It's I was thinking kilometers per second. Its current speed is sixteen point nine two zero kilometers per second relative to the Sun. Sixty one thousand kilometers an hour, seventeen kilometers a second dish thirty eight thousand mile Now, yep, it's going. It's fast. It is the speed I like is in units of astronomical units per year, and that is three point three point six nearly three point five six nine, So three times a year, it covers the distance from the Earth to the Sun. Yeah. Yeah, that's one hundred and fifty million kilometers. Sure is that's that's amazing, isn't it. And it's still going strong. Yeah, so, and it's right. I think the fuel's low. But the fuel is just for the thrusters. It's just to keep the antenna pointed towards Earth. So yeah, and he said it might come across something in about forty thousand years. I thought when we talked about this last that it could just keep going. It might not run into anything. Yeah, simply because it's not aimed at anything. And space is very empty. Even though there's a you know, four hundred billion stars in the Milky Way or whatever. The Milky Way is very very big, indeed, and it's look, it's it's distances. I think. I think the olds are that it will keep going forever. It might be captured by the gravity of another star. I think the notion of a collision is vanishingly small. I've just statistics just come into my head that I used to use a lot to give people the idea of just how big the galaxy is. And I'm sure you and I have discussed it too. If you imagine a diagram of our galaxy that was the size of the Earth, so twelve and a half a thousand kilometers in diameter, that's your map of the galaxy the size of the Earth. The separation from the Sun to the Earth on that scale is two millimeters. That tells you that the galaxy is very, very large compared with the size of the Solar System. That's just mind boggling stuff. It's really easily. And the other thing, I suppose we talk about the odd cloud, which is this thing around our Is it around the Solar system, around a galaxy? Apparently it's around the solar systolic system. They reckon it's going to take three hundred years for Voyager one to reach that. That's right, that's right, that it's a long which means it still hasn't really left our Solar system. In real terms, I'm not even sure that it will be three hundred years because the oak Cloud is about a light year away. Well, actually it says here the inner edge in three hundred years, but it will take thirty thousand years to pass through it. That's more like it. Yeah, it's more like it. I should have finished reading the sentence, shouldn't I there was There was an unpredictable full stop in there though, So yeah. But yeah, incredible. Sorry, I meant to say last time Andy came on, I meant to tell him that I'm a train driver too, But it's and scale, which he'll know. He'll know what that is. Not some people might not. Actually, probably quite a lot of our listeners do. But I drive my trains in and scale. I love it. I should send Andy if he sends me his email address some video of our brand new regional trains in New South Wales that are like to see that being fitted out in Dubbo where I live, and they've been doing test runs on them. I've actually heard it in the wee small hours passing by because it's got a completely different sound, and I've actually reached a point now where I recognize the different trains by sound. Hypathetic as that, but yeah, it's much much quieter than the current train which is the XPT, which is well past its use by date. But never let the New South Wales government, you know, build a train because they will. They will say, okay, it's got a twenty year life, so we'll replace it in fifty, because that's what's happening. But these are very slickly. These are Spanish trains that are being fitted out dubbo and really really lovely piece of kit as Fred would say. So, and he sent me your email address and I will send you a video of our new trains. It's weird watching them run around with nobody in them. It's just no passengers, nothing, just all the lights are on. Nobody's home. Nobody's home. Yeah, if you're on the Metro in Sydney, there's not even a driver on board either. Yeah, I know. I've been on the Metro a couple of times. It's a slick system. One of my boys lives in a suburb where they're just about to complete a metro line. So he's really happy about that because it'll get him to work, you know, three times as fast, so he's really he's thrilled because he got rid of his car. He doesn't use a car in Sydney doesn't see the need. Got to have one out here though in the country. Thanks Andy lovely to hear from you. This is Space Nuts with Andrew Dunkley and Professor Fred Watson. Let's take a short break from space Nuts to tell you about our sponsor, NordVPN. Now. I've talked about virtual private networks before and how they can protect you online, and no one does it better than nord Now. I've been using nord for over two years and I have no complaints. I'm also using some of their other tools, including the brilliant password manager. NordVPN is great for streaming and won't slow you down. In fact, it does the opposite with no interruptions, no limits on bandwidth and no limits on speed. Right now, using the exclusive space nuts offer, you can receive four extra months for free on a NordVPN dot com plan. NordVPN encrypt your Internet connection, hides your IP address, and offers access to over seven seven hundred servers around the world. Plus with features like threat protection, pro mesh net, ultra fast speeds via nord Links, your digital life stays private and efficient, so don't miss out. Visit nord vpn dot com slash space nuts and enter the code space nuts to claim this deal. Remember there's a thirty day money back guarantee, so it's risk free to try. Stay safe, stay private, and browse with confidence. That's NordVPN dot com slash space nuts space nuts. Oh boy, okay o. Next question, I don't even know where we're up to. Where are we up to? We've spoken to Andy, You're right. Question three high space nuts. Ben Harding here from Kent, England. Having listened to your show for several years now, I know everything there is to know about black holes. Indeed, I am ready to start building my own any day now. But wait. If I build two and they crash together, they will create gravitational waves, and I need to account for the ensuing distortion of the fabric of space time. All my cats will be upset. So our gravitational waves spherical or flat? I'm thinking they must be spherical, But then again, if they are created by two objects spiraling in together, the waves may be flat by some sort of conservation of angular momentum rule. I hope you can help me with my cats. They get a bit scratchy when they're upset. Thanks for the awesome show, Ben. I thank you, Ben. I'm just imagining your cats freaking out over gravitational waves. There's a comic strip in that, I reckon somewhere. My brother would do a comic on that. I reckon. He's very artistic, is my brother? Okay? All right, So our gravitational waves from the cataclysmic collision of two black holes spherical. So I think what Ben is referring to in his description is whether they whether they're they're radiated. Gravitational waves are radiated in all directions what we would call isotropic, or just in a plane, in the plane of the collision. And to the best of my understanding, the answer is that they're isotropic. They go off in all directions. So space shutters are just because of the gravitational interaction. It's not got any prefer I don't think. I do not believe it's got any preferred direction because of the you know, the direction of the collision. I think it's it's the same in all directions. There's another way of interpreting Ben's question, though, and that is how the oscillations of gravitational waves take place. And they're not the same as sound waves, where which are compression waves where things push backwards and forwards. And they're not the same as light waves, which are transverse waves where the electric field and magnetic field vary in a transverse manner, in other words, opposite to the direction of propagation, or right angles to the direction of propagation. There's something called quadruple waves, which is a sort of combination of not quite a combination of the two, but certainly a slightly unusual form of transverse wave. Quadruple waves is what they are. But I don't think that's what he means. I think what Ben means is what I answered in the first place, that yes, they're isotropic, rather than limited to a particular plane. They go out in all directions, unlike the gravitational wave that I detected on a plane. I don't know what that guy was eating, but yeah, I hope I don't have to experience a kid. Yeah, I know those things as well. Pretty awful stuff. Really. I'm impressed that Ben says he knows everything there is to know about black holes. Does that mean we've been doing a job That means he knows more than us, which, yeah, well it is to do possible too. Yeah, yes, but we're learning more and more about them. But that's of course we're listening to our listeners. That's that's exactly right. But yeah, there've been the topic of I think since we started a decade ago. Fred, you reminded me earlier it's been ten years we've been doing this podcast. That's that's extraordinary. We should have had a party, but I think we just can't stay up that late anymore. But it's it's probably been the hottest topic on Space Nuts since day one. Is black holes, closely followed by dark matter, dark energy, and I don't know where you go from there, but it's been a life in space. Yes, life, Yes, you are right. Those are the top four topics. So I expect next week our four questions will be on black hole's, dark matter, dark energy and life elsewhere. There's a good chance they will. That will be the standard. Yep, very good, Thank you, Ben. Lovely to hear from you. Hope all is well in Kent. Our final question comes from Judd. Goody, Fred and Andrew. It's Judd from Brisbane. Been a big fan of the show for a long time. My wife and I were listening to a recent episode where one of the stories was about the spun out asteroid that's spinning at an incredibly fast rate. And you know, we found Andrew's thought experiments about how that would affect Earth if we were spinning at a similar rate, And yeah, I got my head spinning and came up with lots of other thought experiments. First, my question is what is the current speed of the Earth's rotation? And yeah, does that speed affect the pull of gravity that. We feel on Earth? Like for instance, if I weigh one hundred kilograms at spinning at this rate of speed, if the Earth stops spinning tomorrow, would I weigh significantly more? Just wondering about that. And another question, would I weigh less at the equator than I would standing at the North or Soft pole because the equator is spinning much more rapidly than the Earth is at the poles. So just some thoughts to make your head spin and maybe give me some answers. Thank you, Thank you, jud Thanks to you and your wife for being fans of the show for so long. Much appreciated. And we can make this quick, yes, and we're finished for that. No, there's a lot more to it than that, but I think he pretty well nailed a few of the thoughts that he's had in terms of what the answers are, what is the current speed of Earth's rotation? If you listen to the Monty Python song from the Life of Brian or was it one of the others, Yeah, they were wrong, weren't they with their assessment of the speed of the rotation of the planet. I can't remember. I do remember, I don't know what the speed is. I'll get to that in a second. I can't remember what the song says, but I do remember listening to that song a long time ago and thinking, yeah, pretty well, most of the astronomical statistics in it are correct, or they were when it was written in the day. But Jod is right. The speed of rotation at the Earth on the equator, which is where your linear speed is maximum, is sixteen hundred kilometers an hour. So that's significant. It's about half a kilometer per second roughly, and that's why you tend to build space launch sites at the equator, because you've got that additional zero point five kilometers per second. That's quite significant when you're trying to get up to eight kilometers per second to get into orbit. So you're kind of a sixteenth of the way they're already just by putting your launch site on the equator and of course launching towards the east, which is the direction that we're rotating in a middle latitudes. It reduces at our latitude here in New South Wales it's about fourteen hundred kilometers per hour. At Jud's latitude in Brisbane it's a little bit less, not that much less though, But so what's the effect on your weight? That's the interesting thing, And there are two parts to this. One is kind of what we've just alluded to, the fact that you are rotating sixteen hundred kilometers an hour roughly one thousand miles an hour. It basically there's a centrifugal force that means that you are slightly lighter. Your mass doesn't change, of course, but your weight does because of that centrifugal force. But there is another effect that acts with that too, and that's because the Earth isn't sphery cool. It's slightly bulging in the centric it's what we call and a blazed as spheroid. And at the equator you're about twenty kilometers are further away from the center of gravity then you are at the poles and so that too reduces the gravitational poll that you feel. So those two things together, the equatorial bulge of the Earth and the centrifugal force of the Earth's rotation come they basically combine to give you a figure that's a bit less than one percent of your weight changes if you're at the equator compared with the pole. People maybe, yes, yeah, I mean it means that if you do weigh one hundred kilograms then at the equator, then you're only going to be ninety nine at the pole. No, I've got it another way around. If you're a hundred kilos at the pole, you're only going to be ninety nine at the equator. I knew what you mean. Yeah, yeah, it's fascinating really and yeah, that was one of his questions, weight at the equator versus the part what would happen if Earth stops spinning? Like, I think we'd all be doomed for starters that the. Right, But we'd all be projected eastwards at sixteen hundred kilometers an hour if you're on the equator, Yeah. Yeah, that'd be pretty messy. But yeah, but if they are stopped spinning, you'd only have that equatorial bulge component that's reducing your weight, the fact that you're a little bit further away from the center, and that's almost negligible on its own. Yeah, fair enough, that was easy. And I found that mudy Python song. It was from the meaning of life, not from the life of Brian, and it's called the Galaxy Song. And the first verse, first verse is just remember that you're standing on a planet that's evolving and revolving at nine hundred miles an. Hour, which is yeah, all right, so it's it's there's a bit one hundred miles an hour slow, yes, but it rhymes that's it a thousand works Yeah. Oh well maybe they needed two words rather than no, I would have still been or Andrew. Maybe the Earth has speed it up since they recorded the song. That's what it's slowing down though, isn't it. Yes, yeah, well eventually this song will be right, Yes, it will. That's right. Good, all right, thank you so much. Jud lovely to hear from you. I hope all is well in Brisbane. Sorry about your football team not and I think that brings us to the end. If you have questions for us, we would love to hear from you. You can go to our website Space Nuts dot Io and click on the am a link at the top of the page where you can ask me anything or ask me and I'll give it to Fred to figure out. So send us text and audio questions. Don't forget to tell us who you are and where you're from. And a little request if you will. When you next listen or are listening to us right now, please leave a review on whatever podcast platform you use, because reviews are very handy. It sort of moves us up some lattery thing ranking thing, which is very good for us. Apparently, I don't understand how this works. It's all to do with gravity. And thank you Fred once again for helping us out today. I think he did all the work. Actually, nice to help Andrew, always good to talk and we'll touch off again. We will Professor Fred Watson, Astronomer at Large. And thanks to Hugh in the studio although he couldn't be with us today. He had a thought and it was experimental and he's going to go and investigate at right now and see if it's real. I don't know what that means. And from me Andrew Dunkley, thanks to your company. You will see 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.