Cosmic Comets, Magnetic Pole Puzzles & The Enigma of Time | Q&A

Hello again, and thank you for joining us on a Q and A edition of Space Nuts. Andrew Duncley here, thanks for your company today. We've got four questions to answer. Actually that usually ends up being ten because people ask multiple questions. I suppose you've got to use your time wisely. But we've got a question about the journey of comets. We've got a question about magnetic pole reversal. We've had that one before, but it was quite a while back. It's worth revisiting. The origin of time has been brought up, and the age of the universe versus galaxies far far away. We'll tackle all of that on this episode of Space. Nuts fifteen in Channel ten nine ignition sequence Space Nuts or three two Space Nurts as the Nights reported Bill's goods and. Joining us to unpack all all of that is Professor Fred What's an astronomer at Large? Hello Fred, Hello Andrew, Nice to see you again. Good to see you too. Haven't changed much since our last laid eyes on you. It's fully funny you should say that look looking good, looking good. Let's do some questions, shall we? Why not more ross blow here so we might as well? Yes, and nice to get a couple of new voices on the audio question list, and of course if you do have questions for us, jump on our website and send them through. Just click on the Ask Me Anything button ama up the top or it's more of a link. And if you've got a device with a microphone you should be able to record a lot. A few people have had issues with it lately, so maybe that's the reason why we're sort of questions. But anyway, we've got a couple. This first one comes from Andrea. Hi, Andrew and Fred. This is Andrea from Wanneroo in Perth, Western Australia. Question is around comets again and how do they How is their you know, pass created and tracked like their elliptical path? Do they all follow us. As similar. Journey or do they create their own as they come through? Thanks has appreciate it and love to show thanks Andrew. Lovely to hear from you, and nice to get a new voice into the into the program. And want a roo I think that's an Aboriginal word for wanting a pat kangaroo. No, I wouldn't have got there. I couldn't it myself. So Andrea's question is all about the journey of comets. Do they kind of all do the same thing, or do they figure it out for themselves or are they you know, they're real loaners and don't want to do what everyone else is doing. So it is a great question, Andrea, and it's actually got a little bit more to it than perhaps people might think, because comets, as you know, they make their appearance from time to time, and individual comets, some of them fairly regularly. But the story starts much much further away from the Sun than any of the planets, way way beyond the trans Neptunian objects. Those are icy asteroids out there where. We've got this hypothesized, never yet observed, but well established, I think, is the best way to call it, shell of cometary debris, And by that I mean chunks of ice basically, which are the leftovers from the gas cloud from which the Solar system formed. So these are ancient blocks of dusty ice. Let's be realistic. It's where the trade's left their junk after they finished building the solar sits. That's what it is, all right, Yeah, Well, the hypothesized celestial trade is it's the debris. It's the leftover stuff frozen at very low temperatures with the dusty you know, dusty contents as well. So the thinking is that shell of comets when when our sun as it chundles its way around the galaxy, it passes nearby other stars and other objects which gravitationally disturb the cloud. And so from time to time you might get quite large numbers of these cometary bodies being disturbed from where they lie and plunging down into the Fini Solar System. So there's probably a steady flux of these things coming in, but once in a while, because of gravitational disturbances, you'll get a lot more. And that was actually the subject of a book written by two colleagues of mine in Edinburgh called The Cosmic Serpent, when it worked out that maybe comets had actually had a lot to do with shaping the Earth, but impacts from comets when the Sun passed into the start anyway, here we have comets. So here's a mister comet sitting out there in the big Departner's comet sitting out there in the in the oak cloud and falls in towards the inner Solar System in a path that is almost a straight line, but it's not because it is actually an eclip, sorry, an ellipse. Anything that follows the gravity of an object follows in an elliptical path. It's in an orbit that often takes it round the Sun, and so you get that's when the Sun's radiation starts acting on the ice and you start to see it. So that path is determined just by gravity and the gravitation mechanics and sort of determined, well, what the starting point of that comet is in the Oort Cloud. Often, though, there might be an interaction with the gravity of some of the planets in the Inner Solar System, most especially Jupiter, and we think that many comets have their orbits modified by the planet Jupiter, so they become much much shorter, because in an orbit to take you out to the Oak Cloud, you're talking about tens, maybe even hundreds of thousands of years. But we find comets with periods much shorter than that, some even as small as four or five years. Anything with a period of revolution around the Sun of less than two hundred years is called a short period comet, and that includes comet Halley seventy six years. So that came down from the Oak Cloud a long long time ago, interacted with Jupiter that pushed it into a short period orbit. So their paths being modified all the time by you know, interactions with the planets, and sometimes they're modified in a in a really quite serious way. There's a great question, Andrea, and quite nice to think of it in the terms that you put it. What determines the pass that these objects take. It's all about gravity and where they started off from and whether they've you know, whether they've interacted with planets on the way down. You did mention the Oord Claud. They also come from the Kuiper Belt, don't they. The Kuiper Belts are much nearer than the York Cloud, and that there are one or two objects because the Caiper Belt they're pretty icy out there as well, you know that. But there might be rocky objects with a coating of ice, a bit like we think Plutoy's rocky core, slushy ocean over the top ice icy crust, whereas the comets don't have crusts, they're just chunks of ice. And I might mention the Ork Cloud was postulated by a very well known Dutch astronomer, Jan Ort I think in the nineteen fifties was when he said comets must come from a sort of reservoir somewhere, a cloud of comets. And the reason why he postulated that it was spherical aspherical shell is that comets when they come in from the Oak Cloud come in at all different angles. They don't just sit in the plane of the Solar System. Yeah. Well, we haven't seen it though, have we the Ork Cloud? Oh no, it doesn't, so it's still theoretical or we've got enough evidence to know. I think it's the plane at nine. I think there's more evidence for comets for Oak Cloud than for planet nine. You're right, though, I mean the problem is these objects are small. They are typically a few kilometers across, and they're you know, they're light Almost a light year away. Is the distance of the Oak Cloud. It's a long, long way out. It's way way beyond where Voyager one is now at twenty light at twenty three light hours away. It's much much further than that. And so you're not ever going to be able to see individual objects in the York Cloud with our telescopes. But the inferences and all the evidence supports the existence of this cloud. Okay, thank you, Andrew. Fabulous question, and we learn a little bit more about commets. O next question comes from Michael in Canada. Apologies Fred and Andrew. I do not have a dark matter or black hole question at this time, but perhaps this question still might be acceptable. I understand that Earth is somewhat overdue for a magnetic pole reversal, and that this is also not something immediate when it does occur. How likely is it that there might be some extraordinary negative effects on satellites in low Earth orbit? Thank you Fred and Andrew, and thank you Hugh in the studio for keeping these two in line every show. Yes, yes, he's conspicuous by his absence, is Hugh very busy man? Though, let's see, all right, negative effect on satellites in lower Earth or But if we start seeing that magnetic pole reversal, I suppose we should address the fact that it doesn't just happen like a light switch. That's certainly true. Yes, so the evidence for rehear not rehearsals reversals. They probably have to rehearse it as well. But the evidence for magnetic poor reversal comes from what we know from principally rocks deep under the ocean. Ocean bed rocks which have the grains of silicates. They're aligned in a way that you can trace the aarth magnetic history. And so the thinking is, I think this is still the sort of number that people talk about, something like three reversals of the magnetic the arth magnetism every million years. Now, that's fairly fairly slow compared with an object like the sum, which we think reverses its magnetic poles every twenty two years. So that's you know, that poot polary reversal, which we can sense from looking at sunspots, is much faster. So the process seems to be on Earth that you've got a gradual weakening of the magnetic field, which when it reappears is the other way around. And we think it's due to the interaction between the Earth's two cores. We've got a solid metallic core with a liquid metallic core on the outside, and the two are rotating with respect to one another. So it's a dynamo effect which generates a magnetic field. So we're talking about time scales for the reversal of thousands of years. It's not something as you said, it doesn't switch on overnight. The process takes a long long time, and it's i mean, there will be some spacecraft that will last for thousands of years because they're high enough that their orbits are not threatened by decay. However, I think the effects of the reversal of magnetic polarity are going to be negligible compared with the magnetic effects that you get from the Sun's the solar wind and the stream of seb atomic particles that comes from the Sun. I think that's the dominant magnetic force for satellites. They're beyond the protective magnetosphere that the Earth provides. That reversal will produce a reduction in the magnetosphere, and that itself might allow spacecraft to be bombarded more by solar wind particles. So there could be an effect caused by the weakening of the ospognetic field as reversal takes place. Okay, so there is something to that. Yeah, I issueably right, because one of the big dangers we face these days is a direct hit from a coronal mass ejection that could affect our electronics, electro fries, the electronics, and I know emergency services in this country and probably in other parts of the world are building that scenario into their emergency response systems. It's unpredictable. I mean it's it could happen. It may never happen, but it has happened in the past. In the early years of the telegraph, there was one particular case where the system was suffering and suffered a direct hit and no one knew what was going on. It was just a real shock. One person did, and that was an astronomer called Carrington. I can't remember. He's the Carrington event. Yeah, I can't remember his first name. His picture is actually on the current issue of Astronomy and Geophysics, which is the the Royal Astronomical Society's journal, and there's a picture on the front of it. I haven't read it yet, but it's me. Mister Carrington is the title of the article. I'm just trying to look up his name, Richard Richard Carrington Tugton. Yes, so he observed, sorry, I was going to say, he observed a very bright flare on the sun and then that was followed by all these magnetic effects that you've spoken about. So he recorded that flair. Yeah, September the first, eighteen fifty nine was the Carrington event. So yes, Michael, definitely something to your concerns hopefully never, but they can't write off the possibility. Thanks for your question. This is Space Nuts Andrew Dunkley here with Professor Fred what's an Let's take a little break from the show to tell you about our sponsor in Cogni. And if you've ever had your information harvested from the world Wide Web, this is the tool for you. Of course, your information is easily available online. We're talking personal information. We're talking addresses, phone numbers, email addresses, even bank details. If your protection isn't good enough, this stuff gets harvested and it is sold by data brokers. They sell it to other people who then scam you or other people in your name, which is happening a lot. So what is the solution. 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But peace of mind is probably something that we all need in this world of data thieves, So check it out today incognit dot com slash space nuts. I believe that this nation should commit itself we achieving the goal before this decade is out of landing a man on the Moon and returning him safely to the EUROPEUS. Next question, Fred comes from a local Indubo, New South Wales. Hello George, I'm not sure if we've met. I hope we do someday if we have it already, If that makes any sense at all, I have a question about the origin of time. Years ago, I read that time emanates from the ceaseless and never ending motion of energy that pervades the entire universe. It's beautifully written, George. If this universal energy were to freeze or even disappear, would time as we know it still exist or would it be in a state of quintessence or maybe even disappear as well. It seems to me that without the motion of energy to bring forth time, there would be no time. The most interesting conundrum, don't you think. Thank you for the interesting podcasts. Thank you, George. Great to hear from a local. This is something we've talked about time and time again for it. Look, it's a very deep thinking local as well, because George is pretty well on the money. I think what you read about a long time ago might not be current thoughts in this field. But time is one of the biggest mysteries that we have, and we really don't understand it how it arises. We know it's a dimension. We know that in the in the relativity world, time is flexible, we know it bends, but when you look at quantum mechanics, it apparently doesn't exist. So it's a very very peculiar thing. And these two that's one of the reasons why the two theories. The theory of relativity and quantum mechanics while they're at loggerheads because they've got fundamental inconsistencies between them. Now I've tried to follow this argument and debate is taking place at the level of quantum mathematics that is far deeper than my capabilities. From my. Fairly what's the word tawdry degree in mathematics that I have, which I only just scraped. It's a better degree in mathematics than mine. Well anyway, yes, it nearly wasn't a degree at all, only the generosity of the Scottish education system let me fail in exam five times and pass it on the sixth attempt. Yes, it sounds like my driver's license. All right, okay, don't remind me never to come driving with you anyway, I hang have it eventually. Yeah, so that the mathematics that you know, the quantum, particularly quantum mechanics, are quantum theory people theoreticians, that's the word I'm looking for. The mathematics that they use are very very abstruse and obscure to the likes of me. I could probably use the words like Hilbert's pace and things like that, but that's all. Now what I read though, is really interesting that you know it was actually Einstein who said times and illusion. In fact, the quote comes from a letter he wrote to the widow of a friend, a close friend of his, who died, And what he said in that letter was to those of us who believe in physics, we know that the concepts of past, present, and future are only a stubbornly persistent illusion. And he said that because relativity suggests that all of time exists, you know that it's that it's all there, and we see it as an illusion, We see it stepping from one moment to the next. But actually what we're doing is we're just plowing through something that exists in its entirety, which sort of casts all sorts of interesting questions about free will and things of that sort. If if if what's going to happen is already predetermined, what happened to free will? But quantum physics, so I think the quantum theoreticians they don't need time at all in their deliberations. And so what's I think emerging from this is that you've got these two different theories that suggest, and this is the language that they're using, that time actually doesn't exist, that time simply does not exist, and what we see as time actually emerges from quantum entanglement. Now, you and I have talked about quantum entanglement a lot, because it's something that space nuts listeners like talking about and I do too, even though it's not that straightforward to understand. But it's basically how you can if you've got two quantum particles in a state of superposition, which means that you you know, things like their position and their state are not determined until you observe them. If you've got two particles that come together in this entangled means, then they retain this what Einstein called spooky connection at a distance. They retain that in some weird way. How time might emerge from that, or the illusion of time might emerge from that, I have no idea, but it is something that is very much ongoing basically new physics ideas. Now, how do you probe that? How do you find out if these ideas are anything like the truth. Well, it's by looking for holes in relativity. For example, we test relativity all the time. It's good to I think the last time I read about it was something like one party in ten to the power eighteen is how accurate it is. So it's a very very robust theory. If you could if somebody keep trying to break it but they can't. Yeah, find if you could break it, then you might see a chink into the new physics that might underlie what we're talking about now. And likewise, with you know, the subatomic particle world, where we're seeing in the Large Hadron Collider, we're seeing we are seeing new particles. A new one was discovered not that long ago, but it's one that is not sort of revealing any cracks in our understanding of the particle world. Supersymmetry was the buzzword ten years ago where people were hoping that the upgraded Large hundred Collider would reveal evidence of what's called supersymmetry, which might talk about new dimensions and things of that sort. But there's absolutely no sign of it at the moment. So all of that's ongoing. Maybe there will be some chinks that appear. When they do. You and I'll talk about it, Andrew. Wouldn't it be cool? Yeah? I suppose you could. Quite often when we talk about this sort of thing. People get together on the Space podcast group on Facebook and talk about time and some of just say, look, time's a construct, it's not real. And I suppose to a certain degree that's true. We did invent time to suit ourselves on this planet, the construction of various forms of calendar and clocks, but we worked it in with what the planet's doing. That's our version of time. But we're talking about time at a universal level, the progression of existence, I suppose for one of a bitter description. I mean, yeah, to an astrophysicist, time seems to be a fundamental part of the universe because we see things evolving. It's one of the reasons why the Big Bang theory really rose to prominence, the fact that when you look further out into space, you're looking further back in time, and you see galaxies that are clearly different from what they are now you've seen them in the early universe. And of course that is ongoing with the web, telescope and all the weird and wonderful things we're discovering with that. So time is sort of real in that sense, but in a fundamental physics sense, maybe there's a deeper reality that hides underneath quantum theory and relativity, and it's down there where time is made. Wow. Yeah, it's pretty deep stuff. I find it fascinating even though I don't understand, and you know, at an internetellectual level, I just know that when I look at my JPS on the golf course, that tells me I'm behind time because I'm bland too slow. That's a bad as deep as it gets for me. Thank you, George Gee. I love that question. Yeah. I hope we hear from you again, and I hope I run into you somewhere in Dubai place say hello. Final question comes from Tom. Hi, this is Tom from Ireland. Love your show. Something I can't get my head around. I hope you can help. If I stand on the Earth and I have a powerfulm of telescope and I can see, say, a galaxy that's thirteen billion late years away. Now if I turn my head and look at one hundred and eighty degrees in the opposite direction with the same telescope, and I pick out a galaxy that's also thirteen billion light years away. How can those two galaxies be twenty six billion late years apart when the universe is only thirteen point eight billion years old. I asked this question because if I get it right, if I'm assuming right when I see the galaxy just thirteen point eight thirteen billion light years where I'm seeing it as it was in that position thirteen billion years ago, and likewise, the one in the opposite direction, I'm seeing it as it was thirteen billion years ago. So how could both of them be that far apart with the universe only thirteen point eight billion years old? I know I'm missing something, something I just can't get my head around. Thank you, love the show, Thank you Tom. This old chestnut, Fred, this old chestnut come up once or twice over the years, but did put it very, very beautifully though he has test something. Yeah, so well yeah, now what's the solution? Well, so. I think the first thing to understand is that the universe is so we think it's thirteen point eight billion years old. So that's right, that's exactly as Tom says, since the Big Bang. But immediately after the Big Bang, we hypothesize, and there's good evidence for this, that the universe went through a period of what we call inflation, where it expanded from the size of a football to the size of a galaxy in something like a gazillion to a second. Yeah, it was. Something you can't get your head around, isn't it. Yes, so expanding much faster than the speed of light. But as we've said before, the universe can actually do anything. It's not limited by the speed limit which we are when we travel through the universe. When we travel through space, we're limited to the speed of light. But space itself can and indeed did expand at a very very rapid rate. So what we have is a universe that is much much bigger than what we can see. And that sort of explains, I think the issue. Because we from our vantage point here on Earth, when we look out into space, we can only see so far back, and that is because we eventually, at great distance, we run into the flash of the Big Bang. You're looking so far back in time that you're still seeing that the universe when it was a bright fog which was not transparent, So it was this fog of radiation, and we see that as a cosmic microwave background radiation, which we've talked about many times. It's all over the sky's got slight variations in it which correspond to temperature variations because of acoustic oscillations in the Big Bang. In other words, the noise of the Big Bang so that's a horizon. Now we can't see beyond that, Tom, But the universe self goes on. It's almost as though we're in a bubble in a huge universe, and all we can see is limited by that time of thirteen point eight billion years, because eventually we're on into the flash of the Big Bang looking back in time, but because of that inflationary period, the you know, the hypervelocity expansion that the universe went through early in its history, then it's it is much much bigger. So if you all, right, so you see a galaxy that's thirteen point eight billion years ago away, and then imagine yourself standing on that galaxy, you wouldn't see the galaxy that was twenty six billion years like years away, because you're limited by the horizon at the same horizon. From any point in the universe, you can only see back thirteen point eight billion years to the flash of the Big Bang. But the universe itself is much bigger. It's it's a difficult thing to get your head around, and to Tom's conundrum, is absolutely understandable. But that's the answer. The universe is a lot bigger than what we can actually see. Yes, and if you did look in both directions and could see something thirteen billion light years away that way and that way. It stands to reason that from where you are, you're looking across twenty six billion light years. Would that be correct? Yes, but if we own yeah, I mean that's right, and that's you know, the separation between them. In fact, we're talking a little bit enigmatically anyway, because the proper distance to it. So if we have a look back time of thirteen point eight billion years to an earlier baby galaxy, that is the distance that we see presented to our telescopes. But in reality, because the universe has been expanding since the light left it, that is probably more like forty billion light years away. But that's something we call the proper distance. But there's no point in imagining the proper distance or thinking about it, because all the information comes at the speed of light. So, yes, the universe is much bigger than even than we can see, but you know, the distance is I think it's always better to talk in terms of look back time rather than distances when you're looking towards the limits of look back time, which is the flash of the Big bang. Yeah, I'm going to ask, oh, how big the universe is. See what it says? Yeah, how big is the universe? Oh, it's quite a big thing. Square. Well, they say the observable universe is approximately ninety three billion light years in diameter. Yes, okay, so that's exactly what I said. It's forty odd light years to the proper distance of the of the of the of the horizon. But the proper distance takes into account the expansion. That doesn't matter to us because all we can see is what we can measure in light years look back time. Yeah, it's fascinating and confusing all at the same time, really really interesting. But the main comment, the main word there in that AI answer is observable. That's the observable universe. That's all we can see. There's much what we can't see is much much bigger. We can't even put a number on that, can we. No, it could be infinite, no idea. All right, Tom, love your question. Thanks so much for bringing that up. It's always a good discussion point. And yeah, it just keeps you thinking, it does. So thanks to everyone who sent questions in Andrew and Michael, George and Tom and if you've got questions for us, please send them via our website, and you can do that through they Ask Me Anything button at the top ama where you can leave text and audio questions. Don't forget to tell us who you are and where you're from. And Fred's about to find out who that is and where they're from, probably from the other end of the universe. Could be you wouldn't that be a coup indeed? But thanks to your questions and keep them coming. And while you're on our website, have a look around, maybe click on the support our podcast button and see if you can help us out. It's totally optional, and plenty of other things to see and do, including visit the Space Nuts shop and leave some reviews while you're at it. Fred, thanks so much. It's been a great pleasure, lots of fun. Thank you Andrew, some excellent questions. Takes to all hones, Professor Brett Watson, Astronomer at Large. And thanks to Hugh in the studio who couldn't be with us today because time stopped for him, and from me Andrew Dunkley, thanks for your company. We'll 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 bites dot com. This has been another quality podcast production from sites dot com.