Latest / Space Nuts: Astronomy Insights & Cosmic Discoveries / #400: Big Bang Echoes & Eternal Suns: Probing Gravitational Waves and Immortal Earth

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#400: Big Bang Echoes & Eternal Suns: Probing Gravitational Waves and Immortal Earth · Space Nuts: Astronomy Insights & Cosmic Discoveries

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Hi there, thanks for joining us. This is Space Nuts Q and A.
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My name is Andrew Dunkley, your host, and coming up on this
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episode, we've got a question about gravitational waves in the Big Bang. We're
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also going to look at a what if question love the what if questions,
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which is asking about the life of Earth, not life on Earth, the
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life of Earth if the Sun never died. Interesting angle. And we're also
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going to look at time and dark energy. That's all coming up on the
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Q and A edition of Space Nuts fifteen seconds. Guidance is Internal ten nine
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ignition, Space Nuts NY four three two Space Nurse as when I reported Bill's
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good and joining me once again is Professor Fred what's an astronomer at large?
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Hello? Fred? How are you doing? I am doing as much as
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good. Good, good to be Q and A ing with you, Yes
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you too? Shall we get stuck straight? All right? Our first question
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comes. I'm not sure if it's bo or Boa. I have to listen
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more carefully. Here we go, Hello Fred, and Andrews is both here
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from Melbourne. I hope you're well. I have a question for you,
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and it is not about darknessy nor it's about dark matter, but It's is
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about gravitational waves. It's just straightforward question. Did the Big Bang produce gravitational
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waves? As the understand it, gravitational waves that generated when two massive bodies
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such as neutron stars and black holes I lie to each other and cause that
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ripple in the fabric club space time. But when the universe has just begang
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in internet density and so forth, when it came into existence by the Big
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Bang, did it produce gravitational waves or echoes? And can we detect those
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echoes in space and time very much like the cosnic microwave background radiation that we
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see today. Anyway, I hope that makes sense. I love to hear
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you answer. Thanks you very much, Thank you Boa. That's a good
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question. You know, we talk about the Big Bang a lot. We
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get a lot of questions about it, and I mean, it was a
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massive event. We don't know why, we don't know a lot, but
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we know we can see that it happened through the cosmic microwave background radiation that's
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still evident today. But gravitational waves would I mean, if the universe didn't
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exist at the moment of the Big Bang and was being created as a consequence
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of that I'm not sure gravitational waves could have happened the way we understand them
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with other events in our universe. I'm not sure about this one. So
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the thing is, Andrew, the Yes, the universe was created in that
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instant of the Big Bang. And so you're right. You know, in
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the conventional theory standard Einsteinian physics, we we imagine that time and space didn't
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exist before the Big Bang. So you've got to create some space for your
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gravitational waves to go through, which is kind of what you say, yeah
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and so and so, Yes, there was the instant of the Big Bang
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that created this singularity in time and space, followed by this period, was
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it ten to the minus thirty three of a second something like that in duration,
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which we call the period of inflation, when when the expansion really took
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hold, and you know, the universe went from the size of a football
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to the size of a galaxy in something like ten to the minus three of
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the second. And the thinking is, and I'm actually dragging this up from
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reading a few years ago, but that, yes, that inflationary period as
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we call it, would have created gravitational waves. Ah, or maybe a
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gravitational wave, but I was about to say maybe just one being at that
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point, but that the issue is that it is a gravitational wave a very
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very very low frequency. So the gravitational waves that we get from colliding neutron
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stars, for example, they produce waves which are basically have a frequency which
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is in the audio range. Which is why we can, you know,
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turn those gravitational wave signals into an audio signal very easily after you've amplified it
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up a bit, after Ligo has done its magic on it, and that's
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where we get this chirp signal of as to neutron stalisma or whatever merge together
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and eventually, because they're spinning ever ever more rapidly, and so the frequency
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goes up of the waves that are being emitted and then stop at a high
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point because that's where they've coreessed into a single object. Now you can think
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of those audio frequencies. You know, we might talk about something like five
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hundred herts as an audio frequency, or you could take four hundred and forty
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herts as the frequency of the standard a note in the musical spectrum. So
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if let's stick with five hundred, because that's an easy one. So the
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period of time between one peak of the wave and the next is one five
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hundred of a second. And so if you think that's the interval of time
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of a characteristic gravitational wave from two colliding objects. Now the issue, as
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I understand it, is that the interval between peaks in a gravitational wave produced
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by inflation is about the same as the age of the universe. Now it's
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not one five hundreds of a second, it's you know, several several billion
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years, perhaps eve tens of billions of views. It's quite a while since
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I read upon this. So normal gravitational wave technology is simply not equipped to
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detect these low frequency, ultra low frequency gravitational waves. But there might be
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other ways of seeing them. And one of the things people have looked for,
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and I'm not really very well up on this, but there is a
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potential signal in the cosmic microwave background radiation the flash of the Big Bang that
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we see that gives us what the universe looked like three hundred and eighty thousand
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years after the Big Bang. That's what we're seeing there. That radiation contains
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information not just on its brightness, but also on its polarization. You know
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that radiation is polarized a bit like light can be polarized. And I'm not
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really drawing the links very strongly here, but I understand that there are links
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between very low frequency gravitational waves and that polarization signal. So it's one of
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the things that people are looking for to try and detect this polarization within the
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cosmic microwave background radiation. So it's not at all or tough question, but
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it's quite a complex answer. Yeah. Yeah, but the Big Bang itself
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could have initially been one create one gravitational way. Let's try it. Yeah,
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that's more I say, yeah, mmmmm, there you go, Boa,
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You're on on the money. It's just a matter of finding a way
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of seeing them. Would Is it possible to these gravitational waves still bouncing around
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like the cosmic microwave background. Yes, yes, but it's such a lot
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of frequency that you don't actually know it's there. You've got to find another
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You've got to find other ways of detecting it, because there's got not going
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to be any change in the gravitational wave signal over you know, a human
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experimental lifetime. If you've got a frequency whose time interval is made in billions
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of years forget it. Yeah, that's a tough one. Thanks Boa,
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that's a great question and thanks for sending it in. We've got a question
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from one of our regulars, Rennie, who is from Sunny West Hills,
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California. This is a what if question. Theoretically, if the Sun were
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never to die, let's assume it's just never going to die, would the
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Earth eventually erode, decay and die on its own. Yeah, it's well,
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my answer is now, because we'll destroy it first, it could be
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very different. I mean, so if what ren is saying is that,
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yes, the Sun, we know it's going to evolve over the next few
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billion years, and it will change, and that will eventually result in the
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Earth being swamped by the outer atmosphere of the Sun, which might not be
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very nice for anybody left on Earth. But if that didn't happen, if
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the Sun just you know, went on its merry way, being a normal
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star, there will be a few things that will happen over that time scale
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which wouldn't which wouldn't which we know won't happen because the Sun's going to the
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Sun turning into a red giant's going to overtake it. One of them is
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the tidal breaking of the Earth's rotation so that it always faces the moon.
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Day will change from twenty four hours to something like if I remember rightly,
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it's forty two days, that it's about that length of twelve and that's turning
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once and the moon will go around the sky around the Earth in the same
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type. So the Earth and the Moon will constantly face one another with a
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month and a day, which are both equivalent to I think it's about forty
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two forty three days something like that. So that's going to change things quite
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a bit. So that would you know, certainly alter that the atmospheric dynamics
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of the Earth if one side's getting warmed up forty of twenty days rather than
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just one day of day and night. So a lot of things change.
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And yeah, the constant bombardment by the magnetic particles from the Sun. I
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don't know to what extent the earth magnetic field mighty road, but there will
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certainly be changes maybe what a bit, So go ahead, go on,
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now, I was just going to say, if humans were still around in
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that period, would we well, okay, now let me rephrase, would
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we adapt as these things changed and reached that point, would we be able
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to adapt as a species and other life on Earth adapt to live in that
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kind of environment. Well, it certainly. These changes are ones that take
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place very slowly, indeed, and over kind of longer periods than the characteristic
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evolution time to get from you know, one mutation to another, whatever that
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might be for humans. So, yeah, they're slow, and I'm sure
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humans could adapt to them. We're a pretty adaptive species. We might also
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by then be capable of building the megastructures that might protect us from some of
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the Sun's funny things going on. It's hard to know, really, isn't
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it. But I think generally speaking, any questions a good one. What
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happen? If nothing happens to the Sun, does the Earth just sort of
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survive? It probably survives, It will be changed. We might find we're
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all living in plastic domes or something by then, rather than you know,
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because the atmosphere has been so messed about with. But yes, yes,
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I think I think I'm an optimist that humor kind would survive. Yeah.
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No, it's interesting because I mean, we know what's going to happen.
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We kind of know when it's going to happen. But if it didn't,
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it would create a whole array of new challenges for humanity because we would have
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to learn to live in a very somewhat hostile environment, I imagine, because
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the planet would not be the same, and I can't imagine what it would
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be like to have a forty two long for the forty two day long day,
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well, you know, birthdays would be few and fun a twain,
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wouldn't they there would. But you know, we're going to know what that's
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like very soon, because the day on the Moon is twenty you know,
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twenty nine days effectively from one from Moon to another. So yeah, so
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we've already got something like that in store for people to experience. It'll be
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very interesting to see what even the Artemis astronauts on the Moon make of all
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that. Yeah, yeah, very interesting. Rennie, that's a great question.
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Thanks for sending it in. Much appreciated. And next up we've got
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Daniel. This is a sort of dark energy question sort of. Hey guys,
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Daniel from Adelaide here. There seems to be more and more discoveries lately
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in the very early universe that shouldn't be possible because not enough time has passed.
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Late size of galaxies of black holes. I'll go far out here.
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I'd love to share. What if time and dark energy were actually the same
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thing. So we know thro about the second half of the universe that dark
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energy has been accelerating its expansion. Could this there for me that there was
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less dark energy in the first half. And if that's the case, what
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if time actually went slower in the early universe. So from our perspectives,
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what took a really short amount of time actually happened in normal time, with
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normal being in quotes. I previously asked the question on the show whether dark
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energy is related to black holes. I think there was a paper around the
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time that kind of suggested that it was. And we know that black holes
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do to store time. So if time is part of the fabric of space,
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maybe dark energy is two, but it's actually one of the same thing.
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I'm expecting a very quick, simple no, but I wanted to ask
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anyway. All right, thanks, Daniel, is time and dark energy?
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Are they the same thing? You never get a quick and simple note from
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me. Done. You know there was a long drawn out complex No,
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it's not all, but I think in this case, yeah, your thinking
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is interesting. We've talked recently as well about the fact that this new controversial
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theory from Joe Silk at all Over in Baltimore, suggesting that perhaps black holes
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supermassive black holes came first, they were formed in the early universe, and
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that goes a long way to explaining the conundrum that you mentioned at the start
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of your question there that a lot seems to have happened in the first in
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the first few millions or hundreds of millions of years of the universe's existence,
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So we kind of understand the gravitational time dilation effects pretty well, and they're
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actually quite small from our vantage point here thirty eight thirty point eight billion years
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later. And you're right to make the point that dark energy only seems to
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have appeared over the second half of the age of the universe, but that's
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more likely to be it's because it's measurable effect has only become apparent. We
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think that during the first half of the universe's age, the galaxies within the
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universe were close enough to each other the gravitational attraction would have basically kept the
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expansion due to dark energy in check. The accelerated expansion due to dark energy,
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and so it's only when you get past a kind of tipping point where
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suddenly the massive galaxies in the universe is not enough, not strong enough gravitationally
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to break the acceleration of the expansion. By that, I mean brak rather
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than break. It's not enough to slow it down, and so the acceleration
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takes over. And that's why it's a tricky thing just to try and tease
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out. And we've talked about this recently as well, whether the dark energy
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is a constant, whether it's something that's a fact that hasn't changed in terms
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of its release a space, a space expands, it's because there is this
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added impact of the gravitational pull of the galaxies stopping us from basically seeing the
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effect of dark energy the accelerated ex back in the early universe. So I
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think all those things are well and truly understood and kept fairly separate by the
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scientists looking at them. And by that I mean time and dark energy.
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So that's a long complicated new Yeah, yeah, okay. Daniel Winfred says,
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I think these things have been long understood. That's that's his way of
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saying, you're way off, way, way off the mark. I don't
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know, but it's worth asking because otherwise, you know, there's obviously this
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is something people are thinking about. So it's worth asking these these different questions
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to just you know, see see if it's a possibility. Thanks Daniel,
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appreciate that great question. If you've got questions for us, please send them
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in because we could always use them. Just go to our website, Space
18:11
nuts podcast dot com, Space nuts dot io and click on the various links.
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The AMA link will give you access to text and voice audio, or
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When did they change the color of that? Send us your No, it's
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right hand side of our homepage. And don't forget to tell us who you
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are and where you're from. Fred, we're done again, Thank you so
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much. Always a pleasure, Andrew, and I hope we'll stick it doin
18:44
very very soon. It's a distinct possibility. Could be within thirteen point eight
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billion years in fact, yes, thanks Fred, seas soon. Fred Wat's
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an astronomer at large, and thanks to hue in the studio for making our
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lives so much more difficult with these split episodes. But now it's okay uh
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and from me Andrew Dunkley, thank you so much for joining us, looking
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forward to your company on the next episode of Space Nuts see you. Then
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you'll be listening to the Space Nuts podcast, available at Apple Podcasts, Spotify,
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