#400: Big Bang Echoes & Eternal Suns: Probing Gravitational Waves and Immortal Earth

Hi there, thanks for joining us. This is Space Nuts Q and A. My name is Andrew Dunkley, your host, and coming up on this episode, we've got a question about gravitational waves in the Big Bang. We're also going to look at a what if question love the what if questions, which is asking about the life of Earth, not life on Earth, the life of Earth if the Sun never died. Interesting angle. And we're also going to look at time and dark energy. That's all coming up on the Q and A edition of Space Nuts fifteen seconds. Guidance is Internal ten nine ignition, Space Nuts NY four three two Space Nurse as when I reported Bill's good and joining me once again is Professor Fred what's an astronomer at large? Hello? Fred? How are you doing? I am doing as much as good. Good, good to be Q and A ing with you, Yes you too? Shall we get stuck straight? All right? Our first question comes. I'm not sure if it's bo or Boa. I have to listen more carefully. Here we go, Hello Fred, and Andrews is both here from Melbourne. I hope you're well. I have a question for you, and it is not about darknessy nor it's about dark matter, but It's is about gravitational waves. It's just straightforward question. Did the Big Bang produce gravitational waves? As the understand it, gravitational waves that generated when two massive bodies such as neutron stars and black holes I lie to each other and cause that ripple in the fabric club space time. But when the universe has just begang in internet density and so forth, when it came into existence by the Big Bang, did it produce gravitational waves or echoes? And can we detect those echoes in space and time very much like the cosnic microwave background radiation that we see today. Anyway, I hope that makes sense. I love to hear you answer. Thanks you very much, Thank you Boa. That's a good question. You know, we talk about the Big Bang a lot. We get a lot of questions about it, and I mean, it was a massive event. We don't know why, we don't know a lot, but we know we can see that it happened through the cosmic microwave background radiation that's still evident today. But gravitational waves would I mean, if the universe didn't exist at the moment of the Big Bang and was being created as a consequence of that I'm not sure gravitational waves could have happened the way we understand them with other events in our universe. I'm not sure about this one. So the thing is, Andrew, the Yes, the universe was created in that instant of the Big Bang. And so you're right. You know, in the conventional theory standard Einsteinian physics, we we imagine that time and space didn't exist before the Big Bang. So you've got to create some space for your gravitational waves to go through, which is kind of what you say, yeah and so and so, Yes, there was the instant of the Big Bang that created this singularity in time and space, followed by this period, was it ten to the minus thirty three of a second something like that in duration, which we call the period of inflation, when when the expansion really took hold, and you know, the universe went from the size of a football to the size of a galaxy in something like ten to the minus three of the second. And the thinking is, and I'm actually dragging this up from reading a few years ago, but that, yes, that inflationary period as we call it, would have created gravitational waves. Ah, or maybe a gravitational wave, but I was about to say maybe just one being at that point, but that the issue is that it is a gravitational wave a very very very low frequency. So the gravitational waves that we get from colliding neutron stars, for example, they produce waves which are basically have a frequency which is in the audio range. Which is why we can, you know, turn those gravitational wave signals into an audio signal very easily after you've amplified it up a bit, after Ligo has done its magic on it, and that's where we get this chirp signal of as to neutron stalisma or whatever merge together and eventually, because they're spinning ever ever more rapidly, and so the frequency goes up of the waves that are being emitted and then stop at a high point because that's where they've coreessed into a single object. Now you can think of those audio frequencies. You know, we might talk about something like five hundred herts as an audio frequency, or you could take four hundred and forty herts as the frequency of the standard a note in the musical spectrum. So if let's stick with five hundred, because that's an easy one. So the period of time between one peak of the wave and the next is one five hundred of a second. And so if you think that's the interval of time of a characteristic gravitational wave from two colliding objects. Now the issue, as I understand it, is that the interval between peaks in a gravitational wave produced by inflation is about the same as the age of the universe. Now it's not one five hundreds of a second, it's you know, several several billion years, perhaps eve tens of billions of views. It's quite a while since I read upon this. So normal gravitational wave technology is simply not equipped to detect these low frequency, ultra low frequency gravitational waves. But there might be other ways of seeing them. And one of the things people have looked for, and I'm not really very well up on this, but there is a potential signal in the cosmic microwave background radiation the flash of the Big Bang that we see that gives us what the universe looked like three hundred and eighty thousand years after the Big Bang. That's what we're seeing there. That radiation contains information not just on its brightness, but also on its polarization. You know that radiation is polarized a bit like light can be polarized. And I'm not really drawing the links very strongly here, but I understand that there are links between very low frequency gravitational waves and that polarization signal. So it's one of the things that people are looking for to try and detect this polarization within the cosmic microwave background radiation. So it's not at all or tough question, but it's quite a complex answer. Yeah. Yeah, but the Big Bang itself could have initially been one create one gravitational way. Let's try it. Yeah, that's more I say, yeah, mmmmm, there you go, Boa, You're on on the money. It's just a matter of finding a way of seeing them. Would Is it possible to these gravitational waves still bouncing around like the cosmic microwave background. Yes, yes, but it's such a lot of frequency that you don't actually know it's there. You've got to find another You've got to find other ways of detecting it, because there's got not going to be any change in the gravitational wave signal over you know, a human experimental lifetime. If you've got a frequency whose time interval is made in billions of years forget it. Yeah, that's a tough one. Thanks Boa, that's a great question and thanks for sending it in. We've got a question from one of our regulars, Rennie, who is from Sunny West Hills, California. This is a what if question. Theoretically, if the Sun were never to die, let's assume it's just never going to die, would the Earth eventually erode, decay and die on its own. Yeah, it's well, my answer is now, because we'll destroy it first, it could be very different. I mean, so if what ren is saying is that, yes, the Sun, we know it's going to evolve over the next few billion years, and it will change, and that will eventually result in the Earth being swamped by the outer atmosphere of the Sun, which might not be very nice for anybody left on Earth. But if that didn't happen, if the Sun just you know, went on its merry way, being a normal star, there will be a few things that will happen over that time scale which wouldn't which wouldn't which we know won't happen because the Sun's going to the Sun turning into a red giant's going to overtake it. One of them is the tidal breaking of the Earth's rotation so that it always faces the moon. Day will change from twenty four hours to something like if I remember rightly, it's forty two days, that it's about that length of twelve and that's turning once and the moon will go around the sky around the Earth in the same type. So the Earth and the Moon will constantly face one another with a month and a day, which are both equivalent to I think it's about forty two forty three days something like that. So that's going to change things quite a bit. So that would you know, certainly alter that the atmospheric dynamics of the Earth if one side's getting warmed up forty of twenty days rather than just one day of day and night. So a lot of things change. And yeah, the constant bombardment by the magnetic particles from the Sun. I don't know to what extent the earth magnetic field mighty road, but there will certainly be changes maybe what a bit, So go ahead, go on, now, I was just going to say, if humans were still around in that period, would we well, okay, now let me rephrase, would we adapt as these things changed and reached that point, would we be able to adapt as a species and other life on Earth adapt to live in that kind of environment. Well, it certainly. These changes are ones that take place very slowly, indeed, and over kind of longer periods than the characteristic evolution time to get from you know, one mutation to another, whatever that might be for humans. So, yeah, they're slow, and I'm sure humans could adapt to them. We're a pretty adaptive species. We might also by then be capable of building the megastructures that might protect us from some of the Sun's funny things going on. It's hard to know, really, isn't it. But I think generally speaking, any questions a good one. What happen? If nothing happens to the Sun, does the Earth just sort of survive? It probably survives, It will be changed. We might find we're all living in plastic domes or something by then, rather than you know, because the atmosphere has been so messed about with. But yes, yes, I think I think I'm an optimist that humor kind would survive. Yeah. No, it's interesting because I mean, we know what's going to happen. We kind of know when it's going to happen. But if it didn't, it would create a whole array of new challenges for humanity because we would have to learn to live in a very somewhat hostile environment, I imagine, because the planet would not be the same, and I can't imagine what it would be like to have a forty two long for the forty two day long day, well, you know, birthdays would be few and fun a twain, wouldn't they there would. But you know, we're going to know what that's like very soon, because the day on the Moon is twenty you know, twenty nine days effectively from one from Moon to another. So yeah, so we've already got something like that in store for people to experience. It'll be very interesting to see what even the Artemis astronauts on the Moon make of all that. Yeah, yeah, very interesting. Rennie, that's a great question. Thanks for sending it in. Much appreciated. And next up we've got Daniel. This is a sort of dark energy question sort of. Hey guys, Daniel from Adelaide here. There seems to be more and more discoveries lately in the very early universe that shouldn't be possible because not enough time has passed. Late size of galaxies of black holes. I'll go far out here. I'd love to share. What if time and dark energy were actually the same thing. So we know thro about the second half of the universe that dark energy has been accelerating its expansion. Could this there for me that there was less dark energy in the first half. And if that's the case, what if time actually went slower in the early universe. So from our perspectives, what took a really short amount of time actually happened in normal time, with normal being in quotes. I previously asked the question on the show whether dark energy is related to black holes. I think there was a paper around the time that kind of suggested that it was. And we know that black holes do to store time. So if time is part of the fabric of space, maybe dark energy is two, but it's actually one of the same thing. I'm expecting a very quick, simple no, but I wanted to ask anyway. All right, thanks, Daniel, is time and dark energy? Are they the same thing? You never get a quick and simple note from me. Done. You know there was a long drawn out complex No, it's not all, but I think in this case, yeah, your thinking is interesting. We've talked recently as well about the fact that this new controversial theory from Joe Silk at all Over in Baltimore, suggesting that perhaps black holes supermassive black holes came first, they were formed in the early universe, and that goes a long way to explaining the conundrum that you mentioned at the start of your question there that a lot seems to have happened in the first in the first few millions or hundreds of millions of years of the universe's existence, So we kind of understand the gravitational time dilation effects pretty well, and they're actually quite small from our vantage point here thirty eight thirty point eight billion years later. And you're right to make the point that dark energy only seems to have appeared over the second half of the age of the universe, but that's more likely to be it's because it's measurable effect has only become apparent. We think that during the first half of the universe's age, the galaxies within the universe were close enough to each other the gravitational attraction would have basically kept the expansion due to dark energy in check. The accelerated expansion due to dark energy, and so it's only when you get past a kind of tipping point where suddenly the massive galaxies in the universe is not enough, not strong enough gravitationally to break the acceleration of the expansion. By that, I mean brak rather than break. It's not enough to slow it down, and so the acceleration takes over. And that's why it's a tricky thing just to try and tease out. And we've talked about this recently as well, whether the dark energy is a constant, whether it's something that's a fact that hasn't changed in terms of its release a space, a space expands, it's because there is this added impact of the gravitational pull of the galaxies stopping us from basically seeing the effect of dark energy the accelerated ex back in the early universe. So I think all those things are well and truly understood and kept fairly separate by the scientists looking at them. And by that I mean time and dark energy. So that's a long complicated new Yeah, yeah, okay. Daniel Winfred says, I think these things have been long understood. That's that's his way of saying, you're way off, way, way off the mark. I don't know, but it's worth asking because otherwise, you know, there's obviously this is something people are thinking about. So it's worth asking these these different questions to just you know, see see if it's a possibility. Thanks Daniel, appreciate that great question. If you've got questions for us, please send them in because we could always use them. Just go to our website, Space nuts podcast dot com, Space nuts dot io and click on the various links. The AMA link will give you access to text and voice audio, or you can click on the little glass. It's not purple, it's green. When did they change the color of that? Send us your No, it's purple when you hover on it. The youer send us your questions on the right hand side of our homepage. And don't forget to tell us who you are and where you're from. Fred, we're done again, Thank you so much. Always a pleasure, Andrew, and I hope we'll stick it doin very very soon. It's a distinct possibility. Could be within thirteen point eight billion years in fact, yes, thanks Fred, seas soon. Fred Wat's an astronomer at large, and thanks to hue in the studio for making our lives so much more difficult with these split episodes. But now it's okay uh and from me Andrew Dunkley, thank you so much for joining us, looking forward to your company on the next episode of Space Nuts see you. Then 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 nights dot com.