Andrew Dunkley: Hello again and thank you for joining us.
This is a Q and A edition of Space
Nuts. My name is Andrew Dunkley. Thanks for
your company. Uh, in this show we answer
audience questions and we've got,
uh, plenty. Today, uh, Martin
is asking us questions about the Big Rip.
Or is it the gnab gib. We don't know which.
Uh, Mike is wanting to know what was
around before the Big Bang. I think we've had
that one before but we will revisit it. Uh,
questions about colliding neutrons on the
stars and sunsets on the moon.
Ah, how, ah, beautiful. Sitting
there looking out over the Sea of Tranquilly
getting covered in dust a
pina colada that you can't drink because you
know. Never mind.
We'll answer all of those questions on this
episode of Space Nuts. 15 seconds.
Professor Fred Watson: Guidance is internal. 10,
9. Ignition sequence start.
Space Nuts. 5, 4, 3, 2.
1. 2, 3, 4, 5.
Speaker C: 4321.
Professor Fred Watson: Space nuts astronauts report it feels
good.
Andrew Dunkley: Joining us again to solve all of those
riddles is Professor Fred Watson Watson,
astronomer at large. Hello Fred Watson.
Professor Fred Watson: Hello Andrew. Good to hear your
uh, conjectured sunset. Uh, drinks on the Sea
of Tranquilly. I hope I can join you for it.
Andrew Dunkley: Even if you could suck on that straw. Uh,
lunar regolith probably doesn't taste very
nice.
Professor Fred Watson: That's right, yep.
Andrew Dunkley: But um, yes, one day someone will be sitting
in a, um, in a building looking out over
the lunar surface, probably, you know,
downing a beer or who knows what,
uh, or maybe they'll just have to suck it out
of the, the air in front of them because of
the gravity. Who knows? Um, shall
we get down to business and see if we can
solve some of this stuff?
Professor Fred Watson: Why not?
Andrew Dunkley: All right, our first question comes from
Martin. Now this was a really long involved
question and I' um, I
hope Martin will forgive me but uh, I sent
you the whole question but I'm just going to
do the precede version so that we're not here
for the next 25 minutes reading out. It's not
that long but anyway, uh, gents, thanks so
much for the podcast. That was the question.
No, I have uh, some questions about the Big
Crunch now it seems to be back in vogue.
One, is it in fact now the favoured
theory? And two, also if we
do get a Gnab Gibson in a
lot of ways it sounds like a super ultra
hyper massive black hole with all the matter
and energy of the universe gathering to a
singularity. Which one is it? And
uh, why? Uh, that's Martin from
Melbourne of course, he goes into a lot of
detail within his question, with
possibilities and ideas and concepts and
lefts and rights. But yeah, um, we have
talked about the, um,
the Big Crunch making a comeback. They're
starting to. Although we are still seeing an
expanding universe, it's just not
accelerating like it was, I think.
Um, so that's what's brought the Big Crunch
concept back into vogue. But, um,
at the moment, the Big Rip seems more logical
given what's happening.
Professor Fred Watson: Yes. So
it could be neither. That's
true. You're right.
Um, and Martin's right that we've seen a lot
of discussion about the
possible reduction
of, um, the acceleration.
So the
universe is expanding. We've known since
1998 that that expansion is
accelerating. Uh, that is the work
that got, uh, Adam
Reese, um, saw Perl
Mutter and uh, Brian Schmidt, their
Nobel Prize in 2011.
Now, um, the recent
evidence from the Dark Energy survey, because
we think that's caused by dark energy. We
think it's caused by an energy of space
itself. That, uh, means
that as space gets bigger, it has more
energy. And so it gets bigger, faster.
That's the bottom line. Now, dark energy is
the big puzzle. Um, what is it? Uh, how does
it behave? So the Dark Energy
Survey, which we've talked about recently,
it's presented some results, has
suggested that, uh,
um,
the acceleration may be decreasing,
um, but it's not by any means
confirmed. That still,
uh, sort of new research,
it needs a lot of verification.
Um, and even if that was
verified, we'd need to know just
by how much it is decreasing,
uh, and what phenomena might
lie ahead in order to predict
a Big Crunch or a gnab gib, as
Brian Schmidt always put it. Not a missing
BG brother. Was that Martin? Yes, that
was another Martin. If you said that.
Andrew Dunkley: Yeah, Martin Berman Govine.
Professor Fred Watson: That's the man. Yes. Um, so it's still.
I, um, think it's still a, uh, fairly
speculative idea. Uh,
I think it's very speculative that we might
end up with a Big Crunch. Uh, it's still
speculative that the acceleration is
decreasing. And I was looking, uh, a couple
of days ago at another paper,
um, actually written by, um, a
big group of authors, including some
luminaries from Australia. Ah, also
Brian Schmidt and Adam Reese, who I was just
talking about. Now, uh, they are also on this
paper, they've done a very, very careful
reanalysis of the data. Ah,
that basically was, um,
what we based the initial idea of dark
energy on. The accelerating universe. It's
all about supernova explosions. Um,
because there a recent paper that
suggested that the acceleration wasn't real,
uh, because of phenomena to do with
galaxies. But, um, it turns out that,
yes, it is definitely real.
The acceleration has been firmly confirmed.
But what hasn't been confirmed is that
it's decreasing. So at the moment, I think
the Big Rip is still the likely, you know,
the likely outcome that the universe gets so
big that space starts tearing itself to
pieces. I find that very hard to imagine.
Andrew Dunkley: I do too.
Professor Fred Watson: Um, but that seems to be the more likely
outcome than a big crunch. Or it might just
keep going forever. Look, we're talking
so far into the future now. With the
observations that we can make at the moment,
it's very hard to make any firm predictions.
Andrew Dunkley: You know what I can't get my head around,
Fred Watson, is that, uh, we've got an
expanding universe. It's expanding
at an accelerating rate. Makes me wonder
how much bigger it's getting every second
because it's expanding out in all directions.
Professor Fred Watson: It is. And actually that's a parameter that
we don't know. Uh, um,
well, no, that's not quite true. Um, there
is something that we call the scale factor.
It's just a measure of the scale of the
universe and that's getting bigger.
Uh, so
you can talk about the scale factor. You can
say that now it's, uh,
X amount bigger than it was the day before
yesterday. Um, but in terms
of the physical size of the universe, we
don't know, we don't know how big it is. Um,
uh, we know that
the expansion extends out to the horizon
beyond which we can't see any further. Uh,
but there's more universe beyond that and
it's still expanding. So we don't know how
far it goes on beyond that. And that means we
don't know how big it's getting. The scale
factor is an interesting one though. Um, and
it's what you get from redshift. If you
measure the redshift, ah, of a, uh,
distant galaxy,
um, that immediately gives
you the geometry, gives you the scale factor
from that redshift, uh, we call the redshift
Z. It's a, a M measure
of how far to the red the spectrum of a
galaxy shifted. And the increase in scale
factor, uh, as you look back,
I should say the decrease as you look
backwards, if you look out to a redshift of
Z, the difference in scale factor
between the universe now and the universe as
it was then is one over one plus Z.
It's such a simple equation. Scale factor is
one over one plus z. Uh, that's the
change in uh, scale factor and that's an
absolutely rigorous geometrical equation. So
we do know the scale factor changes but we
don't know what it means in terms of physical
size because we don't know how big the
universe is.
Andrew Dunkley: No, can't see it. Um, but uh,
it must be a massive amount of
inflation uh
every second if it's accelerating outwards
and it's already as big as it is. I mean.
Professor Fred Watson: Yes, that's right.
Andrew Dunkley: What's driving all this dark energy? Um,
probably. But uh. Oh gosh,
um, it's unthinkably huge.
But uh. M. Martin, in answer to your
question, uh, there isn't really a favoured
theory, they're just theories.
So it's um, at the moment still
expanding. Therefore the RIP concept's
probably more favourable than the crunch
concept. But maybe it won't be either. It
might just keep going forever and ever until
we bump into something else. I don't know. I
don't know. Maybe it'll be the Big Dint. I
don't know.
Professor Fred Watson: I've got one of those in my car actually.
Andrew Dunkley: Oh, haven't we all? Um, yes,
thanks for the question Martin. It's a, ah,
really interesting one to speculate about.
This is Space Nuts Andrew Dunkley with
Professor Fred Watson Watson.
Space Nuts.
Our next question is an audio question from
Mike.
Speaker C: This is Mike, uh, from Chroma in the uk.
Um, you had a question.
Uh, well on the podcast I'm listening to
the beginning of the universe as in the Big
Bang. Um, you referred to it as
being nothing before it.
Um, surely from uh,
a non science point of view it would be
better to say there was something before
the Big Bang but you don't know what it was.
Um, why do you
refer to it as nothing
before the Big Bang? Bit of a strange
question but I thought I'd ask.
Andrew Dunkley: Cheers, thank you Mike. And I'm
going to make a little correction Mike,
because I think it's me who suggested
that um, there was nothing and I think
Fred Watson corrected me and said well no, we
don't know what there was.
Professor Fred Watson: Is that the one like that? Yeah,
something along those lines. It's nice to
hear from you Mike. Um, we have uh,
Chroma here in Sydney which is just down the
road from where I live. So
you were right to put the words UK after or
the letters UK after Chroma, the
original Chroma.
Andrew Dunkley: We've had a few of these recently with people
from Vancouver in the United States. Where
was the other one? Um, which
wasn't where we'd normally think. Yeah,
anyway.
Professor Fred Watson: Well, yeah, it depends on your perspective,
doesn't it? Yes, it does. If you're in
Britain, Chrome is in the uk.
Andrew Dunkley: Yeah.
Professor Fred Watson: Um, so, so the, yes,
the, I, I mean you can say there was
nothing. Uh, look, the, the glib way of
saying of the origin of the universe is in
the beginning there was nothing and then it
exploded. And that might be what Mike's
thinking of, um, but that
is pointing you in the wrong
direction because
certainly with the best of our knowledge at
the moment, and that excludes things like
ideas of multiverses, because we simply don't
know whether multiverses exist or not.
We have a universe that we know
had a very explosive event
13.8 billion years ago. We believe
it was the beginning because, uh,
the theory of relativity says that, and
relativity, in all the tests we've thrown at
it over the hundred odd years that
it's been, you know, accepted,
um, it survived all the tests with incredible
robustness. So it's worthwhile
believing what it tells you. And
what it tells you is that time started
with the Big Bang. And so,
um, it means that
the word before doesn't mean anything
because there was no time.
Um, it was Stephen Hawking who always
drew the analogy that um, you
know, he said when you look back in
time it's like
um, going along a line of longitude on
the, ah, Earth heading, say northwards. You
keep on going northwards. What are you doing?
You're going northwards. You know where
you're going, you know what direction you're
going in. When you get to the North Pole, it
has no more meaning because you're at the
beginning, you're kind of at the origin of
it. And that's the
analogy he draws, that the Big
Bang, um, time stops
having any meaning. So you can't
describe what came before because before
doesn't exist.
Andrew Dunkley: Okay,
I see where he's getting frustrated though,
because.
Professor Fred Watson: Yeah, well, we all are. Ah, yeah. And that's
because we think in a normal four
dimensional world, three dimensions of space
and one of time. And time is such a
fundamental part of our existence, uh,
that um, it's hard to
imagine something without
time. Um, the
most recent work on this, uh,
looks as though time is actually, ah,
something that emerges from a much deeper
reality. Uh, this is what the people who are
trying to unite relativity and quantum
mechanics say that there's a
deeper reality and maybe time is just an
artefact that in fact some people say
emerges from entanglement. Quantum
entanglement. That works. I have no idea.
But, um, it's a possibility
that we might understand time a bit better,
uh, with some of the outcomes of
some of these theories, and then you might
be able to see. Well, yes, you're right.
Before the Big Bang, there was no time. So
there's no before. It doesn't exist.
Andrew Dunkley: Yeah. And I just did a
speculative question to Chatgpt what was
around before the Big Bang, and it basically
said exactly what you've just said.
Professor Fred Watson: Glad to hear that.
Andrew Dunkley: One of the answers is nothing. Uh, another
one is that, um, um, something
from nothing. A quantum origin, a, uh,
previous universe, which is the bounce model.
Professor Fred Watson: Ah.
Andrew Dunkley: Eternal inflation, multiverse
possibilities, uh, or cyclic universes. I
don't think we've talked about that before.
Um, and look, the
real answer is we just don't know.
Professor Fred Watson: No, but imagine if we could really iron out
what time is all about, then we might have
a bit better idea. We might have some sort of
lever on the Big Bang. The
only physical, um,
we understand the Big Bang quite well in
terms of the chemistry that it generated,
what happened in terms of the energy creating
atoms. That's all pretty well,
um, understood from the particle physics
theory. Uh, but
when you go to the first few gazillionths of
a second, then all these theories just break
down and we've no idea what was going on. But
if we could understand time a bit better,
then that might lead us some insights.
What I was going to say was the only real
measurements that we can make, uh, of the
cosmic microwave background radiation, and
that's been very well measured to try and
understand what the conditions were like
in the Big Bang. Um, um, what you're seeing
then is something that happened 380,000 years
after the Big Bang. So you're not talking
about the first gazillionth of a second.
You're looking at a bright surface which
corresponds with, uh, the time when the
universe was glowing brightly.
Andrew Dunkley: Yeah. My theory is that God was making
breakfast, cracked an egg, and that some of
the whites slid out of the side of the fry
pan and hit the hot plate and there was a
big bang. That's what I reckon happened.
Professor Fred Watson: Yeah.
Andrew Dunkley: Which also proves the theory that the egg
came first.
So, yeah, I solved two problems.
Professor Fred Watson: It's two problems at once. Nobody
can say you don't get good value for money
from space nuts. Very true.
Especially considering it's free. Yeah.
Yeah.
Andrew Dunkley: Unless you want to. But that's optional.
Professor Fred Watson: Unless you want to. That's right.
Andrew Dunkley: Um, but all voluntary. Mike.
Can't answer the question, really. We, we
don't really know what was around before the
Big Bang. If there was anything, I think
would be the bottom line. Thanks for the
question. Thanks for sending it in. This is
Space Nuts, a Q and A edition with Andrew
Dunkley and Professor Fred Watson Watson.
Speaker C: Three, two, one.
Andrew Dunkley: Space Nuts Radio.
Our next question, uh, is from Colin. When
two neutron stars collide, do
any FR Break off? If so,
uh, there could be billions of such high,
ultra high density fragments loose in the
universe. Uh, what would an impact mean
for a planet like Earth? Thank you, Colin.
You make us feel very cosy and safe now,
uh, after that one, um, I would
imagine because neutron stars, uh,
renowned for their intense gravity, are they
not? Would it be more or less
impossible for a bit to break off and fly off
into the universe or could that happen?
Professor Fred Watson: Yeah, um, you're right, Andrew. Um,
they coalesce, they become
one object, um, because of the
extreme gravity. Uh,
uh. And um,
there might be fragments caused, but they'd
instantly be sucked back into the
neutron star. Um, I think it's probably
better to imagine them as two blobs
that uh, that coalesce together once they
collide with a very considerable release of
energy, which we see mostly as gravitational
waves, actually.
Andrew Dunkley: Yeah, well, we're talking ultra high
density in a very small package, aren't we?
Professor Fred Watson: Yes, exactly. Something the size of a city,
uh, with a mass of a star.
Andrew Dunkley: Yeah, um, I think Los Angeles
is probably denser. No, I'm sorry, I couldn't
help that. That was, you know, I'm not
picking on Los Angeles. In fact, I probably
picked a bad target because that's a lot of
people that would be very angry with me right
now.
Professor Fred Watson: But anyway, we just lost half our audience.
Andrew Dunkley: Yes, I think we did. Um, but
no, um, they've got to understand my sense of
humour. But nobody does understand it.
Professor Fred Watson: Not even you.
Andrew Dunkley: Not even me.
But we're talking a
really interesting object in space too. Um,
neutron stars are, ah. Um.
One of the storeys we did not was a while ago
now was about the mountain ranges on neutron
stars. You know, the highest peaks are like a
few millimetres high or something.
Professor Fred Watson: Yes, they were.
Andrew Dunkley: It's very, very weird place.
Professor Fred Watson: Yeah, yeah.
Andrew Dunkley: Um, do we know how they're formed initially?
Professor Fred Watson: Yeah, yeah. By gravitational collapse at uh,
the end of a star's life when.
Andrew Dunkley: So what class of star would have existed to
create a neutron star?
Professor Fred Watson: Big ones.
Andrew Dunkley: Big sort of super blue giant.
Professor Fred Watson: Um, yeah, that's right. That's exactly
right. So, um, stars with a mass,
I think it's two to
sort of. Two to Five times the mass of the
sun or something like that. It um, might be a
bit bigger. Uh, ten times the mass of the sun
gives you a black hole basically. So
somewhere below that but in the upper reaches
will give you a neutron star collapse.
Andrew Dunkley: Okay, so, okay, so
our star won't do that. It's not big enough
to do anything. It's just going to, you know,
retire and find itself a street corner with
a, with a, you know, a beer and a brown paper
bag and a packet of cigarettes. That'll be
the end of the sun. But the bigger they
get, the more possibilities.
Professor Fred Watson: Yes, exactly. Um, look, um, the
sun, uh, is a non smoker
but it will do
something similar because it
will puff off its outer
layers.
Andrew Dunkley: Well that happens to all of us. We get fat as
we retire. So
that's what I'm saying.
Professor Fred Watson: Yeah, yeah. It puffs off its outer layers,
it'll become a white dwarf, will be the
nucleus which itself is an exotic object.
That's something the size of Earth but with
the mass of the sun. Um, um,
um, but its outer envelope will turn into
something very beautiful. Probably what we
call a planetary nebula.
Andrew Dunkley: Yeah, we won't think so.
Professor Fred Watson: We might not, but this will be a long time
after we're gone because we'll have been
swallowed up.
Andrew Dunkley: Exactly. But um, as far
as a neutron star is concerned, you've got
a lot of density in a very small package
with a hell of a lot of gravity. And um, the
easiest thing to do there would be to climb
the mountains. But I wouldn't recommend it.
Professor Fred Watson: No, quite so.
Andrew Dunkley: But the bottom line for Colin is um, bits
might break off in the collision but the
gravity is so intense they get sucked back
in. So no, we don't have to worry about
flying pieces of neutron star hitting Earth
while you're trying to sleep. I mean that
wouldn't be fun at all. Thanks Colin.
Thank you for your question.
Our final question today comes from Bill
in relation. Now this was an audio question
that Bill sent in, but the audio quality
um, was super muff for some reason.
And um, we couldn't use the
audio Bill. But um, sometimes these
things get messed up in the ether. So um,
I listened to it about four or five times and
I hope your name is actually Bill. Uh,
and I hope I got uh, the words right in the
question. But he's basically saying in
relation to the Artemis astronauts witnessing
the solar eclipse and seeing the sun's
corona, would you see the same effect
standing on the moon during a lunar
sunset? And uh, Bill's in, in Dover And
Judy and I were in Dover last year. It's
absolutely wonderful there. Went to Dover
Castle, went down into the World War II
tunnels. Although they've been around a lot
longer than that. Fascinating um, place
and the white cliffs and looked out over um,
over the English um, Channel and it was a
clear day so I could see France. Uh,
yeah. Um, something I've always wanted to
witness. The locals are probably saying, oh
gosh, he's boring. I can see that every day.
Professor Fred Watson: They might like to see a kangaroo though,
which you could see every day.
Andrew Dunkley: Yeah, you know, um, it's
a pest species.
Professor Fred Watson: Yes.
Andrew Dunkley: Uh, because, um, they've really
adapted to um, uh, life
post, um, modern agriculture and um.
Yeah, they're doing well. M.
So, um, yes. So
yeah.
Now we'll go back to the Artemis astronauts
because they did see, ah, when they went
around the moon, they saw um, um, a lunar
eclipse and witnessed the corona. They saw
a few other interesting things as well, like
impact, um, flashes on the lunar surface from
micrometeorites. Uh, but yeah,
um, could you see the same effect
standing on the moon?
Professor Fred Watson: Um, yes. The answer is yes,
because the moon doesn't have an atmosphere.
Um, what there is on the
moon is something called levitating
regolith, uh, which is
soil being lifted as a lunar soil particle.
Basically the lunar dust, very, very fine
dust. Um, and that gets
electrostatically charged up during the lunar
day and tends to fly off the
surface.
Andrew Dunkley: And that's why it ends up in your pina
colada.
Professor Fred Watson: It could be. Yes, that's right.
Uh, so that's right. Uh, so,
um, there could be a little bit
of a dust haze, uh, on the moon
which might spoil your view of the corona.
That's the only thing that I could think of
that would, um.
Uh, it's certainly true that um, the Apollo
astronauts, several of them, yes, witnessing
the. Looking for exactly what we're talking
about the corona of the sun as it rises
above the limb of the moon. They could see
this lunar dust being illuminated
and that's how we know it happens. Um,
there are some quite well known sketches made
by some of the astronauts because it's very,
very faint and with the cameras they had at
that time, it wasn't possible to
directly uh, record it, but there were
sketches that they made. So it wasn't a
solar phenomenon, it's this levitating dust.
Um, but I think you'd see the
lunar corona as well from the surface.
Andrew Dunkley: Okay.
Professor Fred Watson: Maybe one day somebody will find out because
at the moment we've never had a human
Watching a lunar sunset or moon. Sorry?
A lunar sunset or sunrise.
Andrew Dunkley: Yes, yeah, it'll happen, It'll happen.
Professor Fred Watson: It will.
Andrew Dunkley: Uh, yes, you know the way they're talking,
within a very short period of time, there
will be permanent habitation on the moon
of some kind. Research stations, maybe, um,
power generators, I don't know. They've got.
There's a lot to do and as we mentioned in
the last episode, there's, uh. They're
already looking at ways of building
infrastructure on the. On the moon using.
Using moon dust. So, um. Yeah,
we'll get there. I was going to say
eventually, but I don't think it'll be
eventual. I think it's. We're at the dawn of
it.
Professor Fred Watson: Yep. So exciting.
Andrew Dunkley: M. But yes, a sunset on the moon could be.
Could be quite fascinating. And thank you,
Bill, for your question. Hope all is well in
Dover. And if got questions for us, please
send them in to us via our website,
spacenutspodcast.com or
spacenuts IO. Click on the
AMA button at the top and, uh, that means
ask me anything. And you can send in text
questions or audio questions. If you've got a
device with a microphone, you're all set. And
that's just about everything these days. And,
um, don't forget to tell us who you are and
where you're from and have a look around on
our website while you're there. And, um,
please leave reviews wherever you listen to
us because they help, apparently. I don't
know what they help with. Probably someone
else getting paid, I don't know. But, um,
yes, reviews are always good. They move us up
the pecking order. Number one in Iceland.
Um, but yeah, uh, it's all good stuff.
And Fred Watson, thank you so much. It's been
good to talk.
Professor Fred Watson: It has. It's been a, um, great pleasure as
always.
Andrew Dunkley: We'll catch you soon. Professor Fred Watson
Watson, astronomer at large. And thanks to
Huw in the studio, who couldn't be with us
today because he likes pina coladas and walks
in the rain. Not much into health food, but
he's into champagne. That's why he's under
the table. Couldn't join us today. And from
me, Andrew Dunkley, thanks for your company.
Some people will get that joke. See you on
the next episode of Space Nuts.
Professor Fred Watson: Bye. Bye.
Andrew Dunkley: You've been listening to the Space Nuts
podcast, available at
Apple Podcasts, Spotify,
iHeartRadio or your favourite favourite
podcast player. You can also stream On Demand
at bytes.
Professor Fred Watson: Com.
Andrew Dunkley: This has been another quality podcast
production from Bytes. Com.
Speaker C: Um,