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

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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

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00:18:11.079 --> 00:18:15.240
nuts podcast dot com, Space nuts
dot io and click on the various links.

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00:18:15.279 --> 00:18:22.319
The AMA link will give you access
to text and voice audio, or

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you can click on the little glass. It's not purple, it's green.

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When did they change the color of
that? Send us your No, it's

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00:18:29.920 --> 00:18:33.160
purple when you hover on it.
The youer send us your questions on the

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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

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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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00:19:18.720 --> 00:19:23.480
iHeartRadio, or your favorite podcast player. You can also stream on demand

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at bites dot com. This has
been another quality podcast production from nights dot com.