Probing the Dark Unknowns: Seeking Clarity on Dark Matter and Energy | #385

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Hi, Andrew Dunkley here, and
just want to say thank you for listening

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to Space Nuts throughout twenty twenty three. Fred and I are taking just a

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couple of weeks off, but we
will be back early January. In the

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meantime, here's a repeat episode from
early twenty twenty three, one of our

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Q and A episodes, Space Nuts. Hello, and welcome to Space Nuts.

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My name is Andrew Dunkley, your
host. It's so good to have

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your company. And being episode three
hundred and forty five, we dedicate the

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entire show to questions from the audience, and we're going to do a bit

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of a mix of audio and text
questions today. We'll fit in as many

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as we can. We've got five
hundred of them here. We might get

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two or three, we'll see how
we go. We'll be looking at the

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rotation curve of galaxies and walking on
neutron stars. Will also be chasing up

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the previous episodes, talk on asteroids, dark matter, dark energy, white

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holes, the period of inflame,
and much much more. Coming up on

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this episode of Space Nuts fifteen in
Channel ten nine ignition sequence Space Nuts or

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three two Space Nurse, as the
Nights reported, Bils good and joining me

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to answer all of those questions and
more is Professor Fred Watson, an astronomer

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at large. Hello Fred, Hello
Andrew, it's great to see you again.

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You too, after it's been so
long, been so very long.

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Tongue in cheek. Yeah, well, actually we should just blow the whistle.

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We're doing catch up episodes because you're
going to be away for a bit.

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I'm going to be away for a
bit. Adds up to a long

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period of time where we won't be
able to record, so we're working ahead

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of time. But for you who
are listening, it is at the right

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time anyway, so it doesn't really
matter that I'm explaining that like I am.

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We might as well get stuck straight
into it because we've got a lot

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to do, so we will just
go straight into question one, which comes

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from Rusty and our favorite wa town
of Donnybrook. Hey, Fred, and

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Andrew was Rusty and Dinnybrook. I
hope you are keeping cool in our extended

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summertime here in Australia. Fred,
you once famously remarked on this show that

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spiral galaxies, when viewed in infrared
light, completely lose their spirals. You

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don't see them at all. In
infrared. And so I'm wondering, since

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most of the visible light is from
the spirals, and almost all of the

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ultra violet light is also from the
spirals, how does the rotation curve vary

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with wavelength? Thank you? All
right, thank you. Nice to hear

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from you, one of our regulars. Yeah, we did talk about that

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before, and it became apparent that
when you view a galaxy spiral galaxy through

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infrared, there are no spirals.
And yeah, it's got rusty thinking.

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Rusty has an interesting mind. He
thinks about a lot of things. Yeah,

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And actually, Andrew and Rusty,
what's given the lie to my comment

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about the spiral arms disappearing in the
infrared is some beautiful James Webb's based telescope

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images of galaxies wow, which have
sensational spiral arms. Okay, but you're

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you're seeing. So what I said
in the originally is that if you look

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in the infrared, you're you're seeing
dominant galaxies dominated by old stars, and

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they tend to be yellowish in color
rather than rather than in you know,

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rather than blue and white as the
young stars are. And so they they

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do. And it is true that
the galaxy itself has this underlying population of

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these elderly stars that have been there
a long time. So you're an elderly

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star. Well, yes, no, I'm just old. Im there's you

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know, there's just no bitting about
the book, in fact, bordering on

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the ancient. I think they could
say so anyway. Yeah, so,

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so there's an underlying population of old
stars, including me and he, and

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they tend not to delineate the spiral
arms. Then if you look at you

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know, most most images of galaxies, and particularly the early black and white

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ones which were sensitive to the blue
actually rather than the red, they show

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the spiral arms because because that's where
the young energetic stars are, the white

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or bluish in color, and they
show up. Now, spiral arms are

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we know, the host the location
of many young stars because the spiral arms

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are caused by sound waves effectively passing
through them and basically sparking them into ignition.

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And so you get short lived,
very bright stars which show up as

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bluish objects in the spiral alarms.
Now, why does the Hubble, sorry,

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why does the James Webb space telescope
show galaxies with lovely spiral alarms?

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And the answer is that what you're
seeing there is the dust in these in

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these spiral arms, predolently the dust, and that dust is being also pushed

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into a spiral shape by the shockwave
the density wave that's passing through them and

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causing the style formation that reveals the
spiral arms the stars themselves the right.

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So that's just by way of a
caveat to what I said, as Rusty

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quoted me as famously having said that
the spiral arms disappear, and it's it's

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still true, but it's certain wavelengths
of light, which brings me to Russy's

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question, how do the rotation curves
vary with wavelength? So if you are

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always looking at stars, you're going
to see you know, you're seeing objects

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whose spectrum is going from from the
ultraviolet to the infrared, but it's the

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same object and so it's the same
moving with the same velocity. So in

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that regard, you know, looking
at stars in different wavebands, you're still

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going to see the same velocities.
But it extends even further than that.

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And that is because and this was
actually some of the work that Ken Freeman

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here in Australia and Vera Rubin did
in the United States back in the seventies,

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demonstrating the rotation curves of galaxies are
flat. They don't behave as you

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would expect if you look at clouds
of gas with radio telescopes, the sort

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of you know, cold hydrogen in
space, which emits at its radiation of

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twenty one centimeters. It's in the
radio spectrum that follows the same rotation curve

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as the stars do, so in
that regard they are the rotation curves are

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independent of wavelength. Okay, very
good. That was simple. Yeah,

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a long answer to a short question, but a good question, Rusty,

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as Andrew says, you always think
outside the box. You do. Indeed,

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Thanks Rusty, and now we'll move
on to North Carolina, which is

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a long long way from Donnybrook.
And one about female listeners. We don't

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get too many questions from our female
listeners, so it's nice when we do.

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Hello, Nan, I'm confused about
gravity, she says, you'd be

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the only one I heard it described
as the curving of space due to the

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mass of an object. Thus,
an object in the vicinity of another object

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falls into the curve, causing the
object to follow the curve. When referring

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to the formation of stars, the
description seems to be that the gas is

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squeezed until it becomes hot enough to
ignite. This is also described as gravity

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acting on the gas. That seems
to be a different action of gravity than

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the bending of space. Help me
understand, Thanks, Nan, what a

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great question. Yeah, that's a
fabulous question. So, yes, it

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was Einstein who said that gravity is
the phenomenon. It's a geometrical phenomenon,

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is what is said. It's actually
about space being bent by any mass that's

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within it, and so, and
that's fairly easy to get your head around

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for something like the Sun, where
you've got this giant ball of gas which

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is gravitationally distorting the space around it. And that's demonstrated by the fact that

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when you look at the Sun in
eclipse, you see stars in the background

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looking to be in the wrong direction, which is how they proved that Einstein's

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theory was correct. But it's probably
less easy to get your head around that

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when you're thinking just of a giant
cloud of gas. So, if you've

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got a blob of gas in space, and that gas is gravitating because it's

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made of matter, then even though
it's pretty tenuous, is out the word,

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Yeah, it's a ten us object. It's not solid like a planet,

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it will still distort the space around
it, and the effect of that

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is once again that the outer edges
of that space will be bent less than

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the regions towards the center where the
mass is concentrated, and you'll get this

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compression effect. The gas will slide
down the bend space, and the effect

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of it is the temperature increasing and
eventually that cloud of gas turns into a

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star. It's the you know,
the mantra is that what is it?

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Matter tells space, how to bend
space, tells matter how to move right.

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That's the That's the and I can't
think it might be John Wheeler who

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said that, Okay, decades ago, but that's the bottom line. Very

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clever. Okay, we're getting through
on fast. We need to slide.

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It's just too quick for my brain. We can easily see. Thank you,

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Nan. Let's go to our next
question, and this one's a sort

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of a speculator from Russ. Hi. Guys love the show. It's Russ

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here from Stalebridge in the UK.
My question is more of a journey that

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we could take. Let's take out
the physics of the impossible. I we

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won't be able to do it.
But let's have a walk across the surface

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of a neutron star. What would
we be seeing on the surface? What

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does what would the surface look like? Would it be glowing, would it

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be white, would it be in
redescent? What sort of colors would we

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be seeing? If we bend down
and touch the surface, what would it

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feel like if we were able to
jump off a little step, maybe your

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foot high? How fast woud we
be going when we hit the surface.

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If we looked up into space,
what would we see? Just can we

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just have a theoretical walk across the
surface of a neutron star? Thanks very

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much, love the show, guys, Take care, Okay, thank you,

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Russ. We have talked about neutron
stars before. I think the very

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first thing that we can say is, as soon as you walk on a

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neutron star, you're you're a mountain
climber. Yeah, because the mountains are,

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as we discussed before, millimeters high, yeah, a few millimeters.

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Actually, something happens to you before
that though, you die of a horrible,

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painful, immediate prispy death. Well
your spaghettifying, all right, just

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like because like a black hole,
you know, the gradient the gravity gradient

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around a neutron star is very steep, so your head's feeling, you know,

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as you walk, your head is
feeling less gravity than your feet,

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and you spaghettified. Basically, it's
not very nice, not pretty. So

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but yeah, what an interesting question. And I think it, I think,

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and I ought to check this,
but I think the surface of a

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neutron star is very very radiative,
so it's beaming out light and I think

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it's probably ultraviolet because it's such high
energy. So it's all the good stuff

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like the human body loves exactly.
Well, you've got now everything else,

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You've got everything. It's it's not
just the gravity and the the blinding intensity

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of the radiation. You've also got
intense magnetic fields that I'll probably screw your

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insides up completely. Stepping off a
doorstep would happen because the doorsteps already been

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squashed as being something less than a
micron high, So there's not much to

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do with looking at the sky from
the neutron star. Yeah, you would

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see it probably would look a bit
weird because there would be definitely gravitational distortion

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effects in the space around you,
and that might cause some strange effects,

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particularly near your horizon with you know, stars compressed one way or the other.

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So it would be an environment that
is very very different, you know,

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assuming that we could magically somehow survive
it, it would be very very

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different from anything we experience on Earth. And that is I guess typical of

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astronomy all pretty well, all the
objects we talk about. If you transported

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yourself from Earth to one of those
objects, no matter what it was,

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even if it's an asteroid, the
phenomena that you would encounter will be so

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different from what we have on our
own planet that it makes for very interesting

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thought experiments and very interesting really and
I hope very interesting podcasts. Indeed,

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in fact, we are so well
adjusted to our own planet because we've spent

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hundreds of thousands and more tens of
thousands of years adapting to this environment,

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just about anywhere else we could go
would not be good for us. No,

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that's right, unless we could find
another planet exactly the same as ours

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in terms of every ways and proximity. Yeah, well, it's you know,

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going around a star like the Sun
rather than a red dwarf that's going

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to spit out all the time.
Yes, No, I mean it's not

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surprising. You know, we've evolved
as creatures of the Earth, so we

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are very well adapted to it.
And you can kind of imagine how many

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million years it might take for humans
to adapt to being on a neutron star

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if they're good. Yes, I
think supermodels would adapt well because they like

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being skinny. Yeah, skinny is
one thing, but spaghettiveations another. The

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one good thing about a neutron star
is that you could walk all the way

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around it in a you know,
much of ours. Is that right?

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Because they're not very big? Are
they the side of a city? That's

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right? So yeah, yeah,
slums down third, it might be thirty

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killing time bus or get mugged.
Probably get mugged the neutron bus. Are

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all right? Thank you, Rus, lovely to hear from you, and

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thanks to Rusty and Nan for sending
in questions to us on this episode three

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hundred and forty five of Space Nuts. Space Nuts. All right, we'll

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just carry right on, Fred because
we have a question from Jeff. This

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is a follow up to something we
talked about in the last episode. Hey

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freend Andrew Jeff in Ohio US eight
here. They just want to clarify a

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couple of biochemical things from the urosl
and an asteroid discussion, and ask a

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question as well about dark matter dark
energy. So, yes, biological processes

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on Earth that make proteins use all
l amino acids, but some biological organisms

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actually use d amino acids make d
amino acids. For example, Anthrax makes

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a polymer out of glutamic acid that's
all D or mostly D. And also

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when we're talking about trying to find
DNA in an asteroid, there's a leading

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hypothesis that actually RNA was the world
before DNA and protein showed up that it

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not only held it genetic material like
DNA does, but also catalyze reactions like

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proteins do, and we still see
evidence of that today. So my question

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about dark matter dark energy, I'm
slightly familiar with these two concepts being described

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as a web that kind of holds
galaxies together and keeps them from playing apart.

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And I think there was some kind
of modeling that showed that, or

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at least try to model what that
web might look like maybe a few years

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ago. And Science or Nature,
did you talk a little bit more about

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the background on this dark energy dark
matter WAB. I'd like to know a

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little bit more on the background,
so I can kind of run of it

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from there. Thanks you guys,
keep up the good work. Really love

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the show. Thank you about Thank
you Jeff, And wow, what on

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a Stuid fellow? He knows his
stuff about RNA and DNA, and yeah,

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very very clever. Brought up some
interesting points I didn't know. Is

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he right that the Earth was probably
more RNA than DNA in the beginning and

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something changed. I'm not sufficiently engaged
with the world of evolutionary biologis and I

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before. I'm very glad that Jeff
put those ideas there, because, yeah,

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we'll follow up on that. Yeah, and I find out what the

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story is that. But his main
question was about one of our favorite topics,

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dark energy and dark matter. And
yeah, he did describe them as

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the web that holds galaxies together.
And we have said before that if there

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was none of these galaxies would just
spin themselves into oblivion. They just go

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in all directions, I suppose,
So yeah, how does it work?

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I suppose was what he wanted to
know. Yeah, so giant space spiders.

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God, you've cut to the chase. David Bowie was right, spiders

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from Mars. There you are spiders
from Mars. Yeah, So we need

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to disentangle dark matter and dark energy
though, because dark energy is not something

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that's part of the web that just
talking about, just talking about the cosmic

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web, which is structures of matter
within the universe. Now, there were

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structures of matter we think were instrumental
in the creation, just as you said,

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Andrew of galaxies, because we find
that when you build models of the

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way the Big Bang evolves, you
end up with this web of material.

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It's almost like a foam, if
I can put it that way, very

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much like cells of a honeycomb,
with the walls between the honeycomb forming the

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structure of the web, which is
there in both dark matter and normal matter.

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The dark matter probably was the first
thing to sort of crystallize into this

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web shape after the Big Bang,
with the normal matter being gravitationally attracted to

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it because dark matter outweighs normal matter
by five to one or thereabouts. So

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that's the hydrogen that followed the dark
matter, and that hydrogen then collapsing into

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stars, gas clouds, galaxies and
all the stuff that we're familiar with now.

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But dark energy is probably uniform throughout
the universe, so it's not part

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of this web structure. The web
structure is just for matter, whether it's

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dark matter or what we call baryonic
matter, which is the matter that we

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can detect that forms the web.
But dark energy doesn't. Dark energy seems

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to be a property of space itself, irrespective of what structures you build inside

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it. The dark energy is there, and the effect of dark energy,

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of course, is what we see
with the galaxy. Sorry, with the

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universe accelerating in its expansion, as
it has been doing for about the last

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five billion years. We think that
before that it wasn't accelerating in its expansion,

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even though dark energy was there.
But the galaxies were close enough together

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that their mutual gravitational attraction resisted the
effect of dark energy. And it was

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only as the universe continued to expand
that the galaxies became far enough apart that

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their gravitational pulled towards each other was
not strong enough to overcome the accelerating effect

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of the dark energy. So that
acceleration is something we've only seen for about,

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you know, half the age of
the universe. Before that, it

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were the universe's expansion was probably slowing
down any furious as to what changed.

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Yeah, the fact that the galaxies
became far enough apart that the gravitational pull

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between them wasn't breaking the yes,
the expansion, and so that allowed the

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dark energy to so we were we
were dominant. We were basically holding it

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back until it reached a release point. And ye, where she went where

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she went quite gradually. But it's
sort of like when you blow up a

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balloon. When you first start to
blow up a balloon, it's really it's

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a hard thing to do, and
then it suddenly gets easier. That's a

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really good analogue actually, because what
you're feeling at first, when you're puffing

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hard against the resist resistance of the
of the of the you know, the

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rubber or whatever really it is,
and that then gets beyond a certain point

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where it's really easy to blow it
up, and if you do it too

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much, it bursts, which is
probably what the universe will do in the

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big Rip in a few trillion years
time or next week, whichever is longer,

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whichever comes sooner. Yes, that's
right. Yeah, Well I hope

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that explain or helps to explain some
of the you know, the confusion there.

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Jeff separate dark energy and dark matter
out in your mind, because they're

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quite different things. But the dark
matter is what forms that web like structure

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that basically is the scaffolding, scaffolding
on which the objects in the universe were

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built. Yes, and as we've
mentioned in previous episodes, they're just badly

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named dark edge. You'll probably be
called something else so that there's no confusion.

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But that yeah, that's where the
sort of crossed up dark matter would

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have been better as invisible matter.
I think, yeah, but dark seems

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to be the buzzword it does,
all right, Thank you, Jeff.

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We've got a text question from Austin, Texas. It's kaos. He says,

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Hello Andrew and Professor Watson. I
will preface this question by saying that

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it may not have a conclusive answer
because it details in the theoretical I was

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pondering the concept of white holes being
mathematically understood but not observed. I wonder

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if white holes could lurk in the
dark matter spectrum of the universe. Just

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like we can't detect the or understand
dark matter slash dark energy, could it

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be possible that white holes exist within
this yet to be understood spectrum of the

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universe. Thanks for a great show. Every week. Much love to y'all.

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I hope I said that right from
Texas. Yehare, that's what it

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had not me him. Good bro, that's very flavorous of it. And

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yeah, some bootscooters are lurking somewhere. There are probably, Yeah, so

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that's an interesting thought. Let's explore
that a little bit, the idea that

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maybe in the dark matter universe,
which we can't detect directly, there are

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objects akin to black holes and white
holes. Let's let's do it both ways,

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okay, And Carlos is absolutely right
that the mathematics of black holes or

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the mathematics of gravitation, let you
conjecture that there are such things as white

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holes. And when you're working in
the equations, I think what you do

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is you reverse the sign of time, so you put times going negative,

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and you've got a white hole instead
of a black hole. But we see

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nothing in the universe that actually could
be one of those, because unlike a

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black hole where nothing gets out,
with a white hole, nothing gets in.

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Yeah, and you'd think you'd notice
that, but I guess that the

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bottom line here is when you all
right, let's think about dark matter,

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we think it is some kind of
species of sub atomic particle and perhaps many

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different species of sub atomic particle excuse
me, which doesn't interact with normal particles.

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So it doesn't interact with light.
We can't see it shining. It

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doesn't interact with matter, you know, it doesn't seem to react with that

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with normal matter. All it does
is displays gravity. It has gravity,

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and that's how we detect it because
as exactly as you said earlier on,

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when we look at the way galaxies
work, if you spot a rotating galaxy

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and if all that you can all
that was in there is all that you

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can see, if that's all there
is, then it should have flown itself

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apart gazillion years ago, maybe on
a millennia ago, but a long time

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ago. It should. It should
can't exist without the idea that there is

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some invisible material holding it together.
And when you do the theory, you

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get the calculation or you get the
almost a picture that shows you that these

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galaxies are embedded in halos of this
mysterious dark matter. Now, dark matter

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reveals itself by its gravity, and
so gravity behaves normally as far as dark

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matter is concerned, which suggests that
if you had a dark matter black hole,

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it would exhibit its forces or exhibit
its present in exactly the same way

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as a normal matter black hole does, because it would be a singularity with

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intense gravitational field around it, which
would pull other stuff in, whether that

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was gas being accreted like it is
at the center of a galaxy, whether

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it's a supermassive black hole, or
you know an x red binary where you've

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00:28:00.839 --> 00:28:04.559
got a companion star that's leaking material
onto the black hole and causing it to

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release X rays. All of that
should still hold good, so that what

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you see in the black hole universe
in real normal matter burialic matter, you

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should also see in dark matter.
Right, okay, interesting, sobly probably

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not is what the answer is,
which saved us a lot of time.

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But we were going slow at the
start, so that's fine. I've actually

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discovered a white hole. Where is
it? It's called my bank account.

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00:28:34.119 --> 00:28:41.680
Nothing gets in, yest in,
but things get out. Yeah, yes,

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that sounds like a white hole.
It's definitely a white hole. All

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00:28:45.240 --> 00:28:49.640
right, thanks Carlos. Let us
move on to Duncan. I think Duncan's

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sent us a few questions in recently, so let's tackle this particular one.

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I think he's looking at the period
of inflation. Hello Duncan here from Weymouth

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00:29:02.440 --> 00:29:08.359
in the UK, questioned about a
period of inflation after the Big Bang when

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the universe expanded faster than the speed
of light. Was that faster than the

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actual speed of light? Or was
it that the speed of light at that

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time was faster than it was now. I'm just thinking that if the speed

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of light in itself at that time
was faster, could it be that there

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is some property of the universe in
which light is able to travel faster than

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00:29:37.519 --> 00:29:41.880
what it does currently in the current
vacuum. And if we could discover what

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that particular property of the universe back
then was, then maybe there would be

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00:29:48.400 --> 00:29:56.480
some way that obviously in the distance
future or current technology to create a drive

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00:29:56.640 --> 00:30:06.240
that goes faster than it. I
don't know, it's just the obviously were

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limited to the speed of light.
But if the speed of light in itself

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could be increased, then who knows? Anyway, Thanks for you help keep

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00:30:15.200 --> 00:30:19.240
up the good work. Well,
okay, thank you, Duncan. Always

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00:30:19.279 --> 00:30:26.240
good to hear from you. And
now I understand how the Americans have learned

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to pronounce things differently to us because
of Duncan's accent. I picked up something

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an American pronunciation in there. I
can't remember what the word was now,

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00:30:36.759 --> 00:30:40.920
but yeah, that's what I was
going to ask you. Yeah, I

347
00:30:41.200 --> 00:30:45.119
just went straight out of my head. It's very late on a Friday here,

348
00:30:45.200 --> 00:30:48.839
so my brain decides to give up
once I've once I've walked out of

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00:30:48.880 --> 00:30:52.680
the office. But a period of
inflation, yeah, we know, you

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00:30:52.759 --> 00:30:56.640
know more, immediately after the Big
Bang, the universe expanded, it faster

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00:30:56.799 --> 00:31:00.160
than the speed of light, and
then it slowed down, and now it's

352
00:31:00.200 --> 00:31:07.359
accelerating again. Weird does Duncan's theories
sit. There's two different things we're talking

353
00:31:07.359 --> 00:31:15.319
about here, Andrew and Duncan.
So the when you think about inflation,

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00:31:15.559 --> 00:31:21.559
the speed of light doesn't matter because
it's the fabric of space, whatever that

355
00:31:21.839 --> 00:31:26.640
is. It's you know, it's
space itself that's expanding. And you know,

356
00:31:26.839 --> 00:31:30.079
you could only talk about being faster
than the speed of light if you

357
00:31:30.119 --> 00:31:34.279
think of two points within that space, how fast are they receding from one

358
00:31:34.319 --> 00:31:37.440
another? And it may well be
faster than the speed of light. In

359
00:31:37.480 --> 00:31:41.599
fact, it would have to be
just because of the way the inflation took

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place. It was an extraordinary period
in the universe's history. But it is

361
00:31:45.440 --> 00:31:55.359
the space that's that's that's that's expanding
very fast, and that doesn't impact the

362
00:31:55.400 --> 00:32:00.720
speed of things going through it.
So one of the basic foundations of cosmology

363
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as we understand it, our theory
of the origin and evolution of the universe.

364
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One of its basic principles is that
the speed of light is a constant,

365
00:32:13.079 --> 00:32:16.160
that it has always been the same
ever since the beginning it was three

366
00:32:16.240 --> 00:32:25.720
hundred thousand kilometers per second. There
are probably still people I hadn't really course

367
00:32:25.839 --> 00:32:30.559
up with this work yet, but
sorry recently, I haven't caught up with

368
00:32:30.640 --> 00:32:35.319
it recently. This is work that
was done a decade or more ago by

369
00:32:35.960 --> 00:32:39.279
colleagues here in Australia, in fact, principally at the University of New South

370
00:32:39.319 --> 00:32:49.640
Wales, who were observing different distant
quasars and there was just some evidence in

371
00:32:49.799 --> 00:32:52.759
those there were spectra. They were
taking the rainbow spectra of these quasars and

372
00:32:52.799 --> 00:33:00.240
look at the features in them.
There was evidence that hinted that some thing

373
00:33:00.440 --> 00:33:07.759
was varying, that one of the
fundamental physics principles was different then than it

374
00:33:07.880 --> 00:33:09.920
is now. Because when you're looking
at as you're looking a long time back

375
00:33:10.519 --> 00:33:16.079
into the past, and the inference
was that it was either the charge on

376
00:33:16.160 --> 00:33:23.200
the electron or the speed of light
that was different. That work was always

377
00:33:23.319 --> 00:33:31.039
greeted with a reception that was less
than worn by the astrophysical community. And

378
00:33:31.079 --> 00:33:36.079
I know why because I've seen the
data and it is really, it was

379
00:33:36.240 --> 00:33:40.359
really, you know, it was
right on the limit of detectability, this

380
00:33:40.640 --> 00:33:47.079
this effect that they were highlighting.
And I suspect that more recent observations because

381
00:33:47.119 --> 00:33:52.519
we've now observed quais as to death
in that, you know, in the

382
00:33:52.720 --> 00:34:00.240
last twenty years or so, I
think with those more recent observations it might

383
00:34:00.319 --> 00:34:04.279
have gone away. However, might
not have done. And I would not

384
00:34:04.400 --> 00:34:08.800
be surprised if we hear from one
of the proponents of that that work and

385
00:34:08.920 --> 00:34:14.199
one of the people who carried it
out, who is a good friend.

386
00:34:15.960 --> 00:34:19.880
I'm going to tell the standard joke
about this gentleman. I hope if he's

387
00:34:19.920 --> 00:34:23.880
listening you won't mind. His name
is John Webb. And the thing about

388
00:34:23.920 --> 00:34:27.920
John Webb was you never met up
with him at the University of New South

389
00:34:27.960 --> 00:34:30.800
Wales. It was always in New
York, of Cambridge or Paris or somewhere.

390
00:34:30.800 --> 00:34:35.079
It was always somewhere else, which
is why he became known as the

391
00:34:35.159 --> 00:34:39.280
Worldwide One. Yes, I remember
this once before. That's a great Yeah,

392
00:34:39.360 --> 00:34:43.199
that's a great nickname. Yeah,
great, it is a great nickname.

393
00:34:43.360 --> 00:34:45.800
Is a great guy as well.
Yeah, you know, and I'd

394
00:34:46.400 --> 00:34:51.639
be nice to try to catch up
with him in Cairo or somewhere to find

395
00:34:51.679 --> 00:34:57.440
out whether he's still whether whether those
ideas are still prevalent. Yeah, I

396
00:34:57.480 --> 00:35:04.679
should look it up. I have
a listener from Kune Barrabin who emails me

397
00:35:04.800 --> 00:35:07.480
quite regularly and listens to Space,
and that's H Barry. He sent me

398
00:35:07.559 --> 00:35:14.039
some nicknames the other day. Keith
kat E t H. It's the nickname

399
00:35:14.119 --> 00:35:20.079
of a bloke with named Keith,
but he only has one eye, so

400
00:35:20.199 --> 00:35:27.960
he's lost his eye. Keith.
Well, I love it. That's a

401
00:35:28.119 --> 00:35:30.320
very clever nickname, very clever nicknase. It's a good one. Yeah.

402
00:35:30.320 --> 00:35:35.199
It's nearly as good as the guy
with the shovel on his shoulder, isn't

403
00:35:35.199 --> 00:35:39.639
it. What's that Doug Dog?
Yeah, yeah, yeah, the guy

404
00:35:39.719 --> 00:35:45.760
floating in the ocean, Bob,
there's a shovel on his shoulder, Douglas.

405
00:35:47.280 --> 00:35:51.639
We could go on forever, but
we probably lose our entire audience.

406
00:35:52.880 --> 00:35:55.800
You've done, Duncan, Yes,
just to return to it. I think

407
00:35:57.320 --> 00:36:02.079
you know, it really is very
principle of our understanding of the universe that

408
00:36:02.159 --> 00:36:09.800
the speed of light hasn't there,
and so engineering the speed of light itself

409
00:36:09.880 --> 00:36:14.639
down the truck is something that I
suspect we would never get to. Okay,

410
00:36:15.239 --> 00:36:19.199
and not for want of trying.
We're trying ways of speeding up our

411
00:36:19.480 --> 00:36:23.079
capacity to move through the universe.
But yeah, getting to the speed of

412
00:36:23.159 --> 00:36:24.840
light, I mean, if we
can get to a fraction of it,

413
00:36:24.920 --> 00:36:30.480
that'll be an achievement. But yeah, full speed of light probably way out

414
00:36:30.519 --> 00:36:34.559
of our realm, given how much
energy is required. Thank you. Duncan

415
00:36:35.000 --> 00:36:38.960
loved the question. This is space
Nuts Andrew Dunkley here with Professor Fred Watson,

416
00:36:44.719 --> 00:36:49.960
Spacenuts. Okay, let us continue
and our next audio question comes from

417
00:36:50.199 --> 00:36:54.880
Mark. Hey, guys, this
is Mark from Baton Rouge, Louisiana.

418
00:36:55.679 --> 00:37:00.119
I really love your shirt. I
understand that one of the lines of reasoning

419
00:37:00.280 --> 00:37:05.840
pointing toward the existence of dark matter
has to do with the comparison of the

420
00:37:06.000 --> 00:37:12.239
rotational period of galaxies to the amount
of matter that they contain. However,

421
00:37:12.400 --> 00:37:16.000
I've seen various estimates of the number
of stars in the Milky Way galaxy,

422
00:37:16.480 --> 00:37:22.159
ranging anywhere from one hundred to about
four hundred billion stars. This is quite

423
00:37:22.159 --> 00:37:27.679
a large Arab war, I would
say, and I'm curious how they can

424
00:37:27.760 --> 00:37:31.440
make this comparison if astronomers are this
unsure of the number of stars in our

425
00:37:31.480 --> 00:37:37.199
own galaxy, much less other galaxies. Thanks, guys, I hope to

426
00:37:37.239 --> 00:37:44.199
get an answer. We hope to
give you on one day. Actually you're

427
00:37:44.239 --> 00:37:47.400
asking the right block because Fred has
been counting stars for all of his career.

428
00:37:49.159 --> 00:37:54.079
Pretty well, that's right, And
yes they you know, the way

429
00:37:54.199 --> 00:38:02.199
you estimate the number of stars in
a galaxy is certainly in our own galaxy.

430
00:38:05.639 --> 00:38:09.039
You're what you're trying to do is
find a way of measuring its mass

431
00:38:10.119 --> 00:38:17.559
and then you turn that into stellar
masses. But one stellar mass does not

432
00:38:17.679 --> 00:38:22.159
necessarily equal one star. So some
of the work, in fact, I

433
00:38:22.320 --> 00:38:28.559
was involved with this work decade or
so ago, by trying to measure the

434
00:38:28.599 --> 00:38:37.679
mass of our galaxy by using the
escape velocity of stars. If you think

435
00:38:37.679 --> 00:38:43.760
about the way stars some stars might
escape from the galaxy, then you can

436
00:38:44.119 --> 00:38:46.519
use that if you this is we
did this with the rave experiment, the

437
00:38:46.639 --> 00:38:52.760
radio velocity experiment, you can actually
deduce back what the mass of the galaxy

438
00:38:52.880 --> 00:38:59.559
is within that radius with it where
the particular star is. Actually it's within

439
00:38:59.639 --> 00:39:02.400
the radi of the Sun, the
Sun's distance from the center of the galaxy,

440
00:39:02.719 --> 00:39:08.519
and you get if I remember Odi, we got one point for trillion

441
00:39:10.920 --> 00:39:17.760
trillion solar masses for the mass of
the galaxy. But that includes dark matter,

442
00:39:19.679 --> 00:39:23.519
so it's not individual stars. So
you know, you've got to know

443
00:39:23.719 --> 00:39:30.079
something about the universe before you make
these calculations, and looking at other galaxies,

444
00:39:30.639 --> 00:39:36.880
it's easier you don't count the individual
stars in the galaxy. And it's

445
00:39:36.920 --> 00:39:39.440
only recently that we've been able to
see the individual stars in the galaxy,

446
00:39:39.920 --> 00:39:47.119
although back in the nineteen twenties Hubble
was observing Cepheid variable stars in the Andromeda

447
00:39:47.159 --> 00:39:51.599
galaxy and that was an early step
in that direction. But most of the

448
00:39:51.679 --> 00:39:53.960
stars in a galaxy are too faint
to do that, and Allly sees this

449
00:39:54.119 --> 00:40:01.519
glow which collects them together. But
by observing so what you're doing is you're

450
00:40:01.599 --> 00:40:08.440
looking at the luminous characteristics of a
galaxy, the stuff that is emitting lines.

451
00:40:09.800 --> 00:40:14.840
Even if you can't see the individual
stars, and from that you can

452
00:40:15.039 --> 00:40:19.639
deduce the stellar mass content that is
emitting the light. In other words,

453
00:40:20.119 --> 00:40:23.199
you've got some handle on the normal
matter. And it turns out that that

454
00:40:23.480 --> 00:40:31.079
is far too little to keep the
galaxy held together. And so that difference

455
00:40:31.119 --> 00:40:36.840
between one hundred and four hundred so
you know, stars in our own sorry,

456
00:40:36.920 --> 00:40:39.159
four one hundred and four hundred billion
stars in our own galaxy. Yes,

457
00:40:39.199 --> 00:40:45.599
it's a four to one error,
but it's still well within the limits

458
00:40:45.719 --> 00:40:50.760
that would be imposed by dark matter. The dark matter itself is much more

459
00:40:50.800 --> 00:40:52.960
than that, is what I'm trying
to say. It doesn't matter whether it's

460
00:40:52.000 --> 00:40:57.480
one one hundred billion or four hundred
billion, the dark matter content has to

461
00:40:57.559 --> 00:41:00.559
be still much more. Okay,
so it is. It's a good question

462
00:41:00.719 --> 00:41:05.000
mark, and you know, it
goes to the heart of how we understand

463
00:41:05.079 --> 00:41:09.920
these things. The it's not just
the rotation of galaxies, of course,

464
00:41:10.000 --> 00:41:16.920
that leads us to believe dark matter
is real. Another very strong pointer to

465
00:41:17.280 --> 00:41:22.679
the existence of dark matter is the
distortion of space by clusters of galaxies and

466
00:41:22.760 --> 00:41:25.760
galaxies themselves. Once Again, if
you look at a galaxy, the space

467
00:41:25.800 --> 00:41:32.719
around it is distorted to the far
more than you could account for simply by

468
00:41:32.760 --> 00:41:37.280
the luminous matter in the galaxy.
It's it's got much more to it.

469
00:41:37.679 --> 00:41:42.039
And that's why we're so booked on
the idea of dark matter, because all

470
00:41:42.079 --> 00:41:45.280
the tests seems to should suggest it's
there. Yeah. Wow, Okay,

471
00:41:45.679 --> 00:41:51.239
I've been trying to count the stars. I'm up to five. So you've

472
00:41:51.280 --> 00:41:52.880
been observing the Southern Cross then,
yeah, I've been. That's as far

473
00:41:52.920 --> 00:41:58.159
as I got. Yeah, oh, hang on to the sun six.

474
00:41:59.119 --> 00:42:02.440
There you've making progress. Well done, you are, Thank you Mark.

475
00:42:02.639 --> 00:42:07.400
And now we've got a question from
Nick. Who is another sandgroper? Do

476
00:42:07.440 --> 00:42:12.960
you know the term sandgroper fruit?
They don't. That's what we call West

477
00:42:12.960 --> 00:42:16.639
Australians. They're sand gropers. So
South Australians are crow eaters. I know

478
00:42:16.760 --> 00:42:21.800
where that comes from. Crow eaters
because back in the day, during the

479
00:42:21.840 --> 00:42:24.519
gold Rush I think or something around
that era, there wasn't much food,

480
00:42:24.599 --> 00:42:29.280
so they used to eat crows.
They used to shoot them. They called

481
00:42:29.320 --> 00:42:34.119
them something else, they called them
desert pigeons or something, but they used

482
00:42:34.119 --> 00:42:37.960
to shoot crows and cook them and
eat them, so they became crows.

483
00:42:37.079 --> 00:42:42.960
I'm still to find out why West
Australian is called a sandgroper though, but

484
00:42:43.000 --> 00:42:45.760
I'm going to find out. I'm
sure it's on the interwebs somewhere anyway.

485
00:42:45.800 --> 00:42:51.960
This sandgroper is Nick from Perth,
who has a question about planetary diversity.

486
00:42:52.840 --> 00:42:58.119
It is a given that the planets
of our Solar system formed by accretion from

487
00:42:58.159 --> 00:43:01.519
a disc of dust and gas circling
around the young Sun, that's the sixth

488
00:43:01.679 --> 00:43:07.440
star in the sky. Gravity inspired
differentiation leading to more dust on the inner

489
00:43:07.519 --> 00:43:14.000
disk and gas of the outer of
the outer resulting in the inner rocky planets

490
00:43:14.000 --> 00:43:17.400
and the outer gas giants all good. Aside from those groupings, what fascinates

491
00:43:17.519 --> 00:43:23.679
me is the lack of homogeneity between
the planets and moons around the gas giants

492
00:43:23.719 --> 00:43:28.519
within these two groupings. They are
so different, all of them. How

493
00:43:28.599 --> 00:43:31.880
did that happen? Can Professor Watson
recommend some reading on the matter. Should

494
00:43:31.880 --> 00:43:36.320
I buy his books? Well?
That's simple answer is yes, Nick.

495
00:43:37.159 --> 00:43:44.159
But it's an interesting observation though,
because we've got rocky planets inside, we've

496
00:43:44.239 --> 00:43:51.119
got gas giants further out, and
yet they've got rocky moons surrounding them,

497
00:43:51.280 --> 00:43:54.480
and ice moons and all this other
weird stuff. Why is it, so

498
00:43:58.079 --> 00:44:02.360
yeah, and which book is it
in? The best one actually is probably

499
00:44:02.400 --> 00:44:08.360
the Kids book. It's the one
where I think I went into the most

500
00:44:08.440 --> 00:44:12.440
detail about planet formation, which I
probably shouldn't have done in the Kids but

501
00:44:12.559 --> 00:44:16.920
but never mind, it was it
was fun to write. So we think

502
00:44:17.039 --> 00:44:27.039
we understand why there is this differentiation
between the inner rocky planets and the outer

503
00:44:27.719 --> 00:44:34.679
gassy ones because of the existence of
the frost line. So if you look

504
00:44:34.760 --> 00:44:44.960
at the distance from the Sun where
water freezes, basically, it's it's kind

505
00:44:45.000 --> 00:44:46.840
of beyond it's the outer edge of
the gold what you might call the outer

506
00:44:47.000 --> 00:44:51.599
edge of the Goldilocks zone. Yees
too hot and it's not too called for

507
00:44:51.719 --> 00:44:54.400
liquid water to exist, and so
you've got and it's between the old bits

508
00:44:54.440 --> 00:45:00.800
of Mars and Jupiter basically, And
that's what you'd expect because the we think

509
00:45:00.920 --> 00:45:07.199
that the idea of water, which
is by far the commonest to element molecule

510
00:45:07.239 --> 00:45:14.440
in the universe, freezing and causing
an increase in the mass of the outer

511
00:45:14.840 --> 00:45:17.400
worlds as the planets were forming.
We think that's why they were able to

512
00:45:17.480 --> 00:45:22.800
hold onto a gas assemblop and become
gas giants, whereas that the inner rocket

513
00:45:22.840 --> 00:45:28.000
planets were within the frost line,
and so it was you know, they

514
00:45:28.039 --> 00:45:32.800
weren't able to do that. So
so that's a neat explanation. But then

515
00:45:35.079 --> 00:45:43.920
the moons themselves, you know,
Nick is quite right that the moons themselves

516
00:45:43.960 --> 00:45:50.079
are diverse, but they are all
basically rocky bodies, rather like asteroids,

517
00:45:51.159 --> 00:45:57.000
with some of them have gotten over
an over layer of water and an overlayer

518
00:45:57.039 --> 00:45:59.440
of ice on top of that.
Many of them, which we've talked about

519
00:45:59.440 --> 00:46:04.039
many times, for some are just
rock like Eo, Some are just lumps

520
00:46:04.079 --> 00:46:08.000
of In fact, some are probably
more like Pommis Phobos. The moon of

521
00:46:08.119 --> 00:46:15.119
Mars is diverse in that regard,
in that more than fifty percent of its

522
00:46:15.199 --> 00:46:21.079
his mass is empty space, which
is what gives it that low density.

523
00:46:21.480 --> 00:46:27.559
So there is still diversity among the
moons even when you consider that. Yes,

524
00:46:27.639 --> 00:46:31.760
they're all basically made of rock,
but maybe the gas giants are as

525
00:46:31.800 --> 00:46:36.360
well. We don't know whether they
have a rocky core. Yes, yeah,

526
00:46:36.400 --> 00:46:38.480
that's one of the mysteries, isn't
it. So it's possible that guest

527
00:46:38.559 --> 00:46:44.199
giants are something of an illusion in
some respects. That's right. They might

528
00:46:44.280 --> 00:46:50.559
be just rocky planet's masquerading as something
else. Yeah, just got massive atmospheres.

529
00:46:51.119 --> 00:46:53.800
Yeah, big atmosphere. Yeah,
it's like a big hairdo really his

530
00:46:54.119 --> 00:47:00.960
which you don't know anything about.
Actually I did once. I'm rapidly catching

531
00:47:00.079 --> 00:47:04.199
up to you as you can see. Yes, all right, Thank you,

532
00:47:04.320 --> 00:47:08.559
Nick, and enjoy groping the sand
whatever that means in Western Australia.

533
00:47:08.639 --> 00:47:14.239
Love Western Australia. Beautiful, beautiful
place. To our final question, Fred,

534
00:47:14.440 --> 00:47:21.039
and it comes from one of our
favorite terraforming experts and sci fi writers.

535
00:47:22.760 --> 00:47:28.079
I'm going to introduce him the way
he introduces us. Hello Martin,

536
00:47:28.760 --> 00:47:38.079
Hello space. That markin Berming Gorvain
here writer extraordinaire in many genres. Today

537
00:47:38.639 --> 00:47:45.039
we're going to terror form a completely
theoretical object. And I would just like

538
00:47:45.159 --> 00:47:53.800
to know what you would see if
you were on a tiplar cylinder and a

539
00:47:55.599 --> 00:48:08.280
circling around it overhead was a a
space ship that Professor Tepplai tells you would

540
00:48:08.320 --> 00:48:14.800
be going back in time. Love
your show. I can't wait for the

541
00:48:14.920 --> 00:48:20.360
answer, Berman Borvain in Potnic,
Maryland, USA, over and out.

542
00:48:20.960 --> 00:48:23.320
Thank you Martin. He's really stretching
now, isn't he. Now. I

543
00:48:23.480 --> 00:48:27.960
just tried to look up what a
tipless cylinder is also known as a tiplar

544
00:48:28.039 --> 00:48:31.039
time machine. It's a hypothetical object
theorized to be a potential mode of time

545
00:48:31.119 --> 00:48:37.199
travel, although results have shown that
a tipless cylinder could only allow time travel

546
00:48:37.440 --> 00:48:44.199
if its length were infinite with the
existence of negative energy. So yeah,

547
00:48:44.480 --> 00:48:49.840
I'm actually looking at the same page
as right and true if it's if its

548
00:48:49.920 --> 00:48:54.000
length were infinite or with the existence
of negative energies. So you've got two

549
00:48:54.079 --> 00:49:01.480
alternatives there, and infinite length is
tricky, does a bit make negative energy

550
00:49:01.719 --> 00:49:07.840
is even trickier. That's why we're
probably never going to build one. But

551
00:49:07.960 --> 00:49:14.239
what an interesting idea it was.
It was it actually is something that falls

552
00:49:14.320 --> 00:49:20.880
out of the equations of relativity,
and in fact, it was mathematicians looking

553
00:49:20.960 --> 00:49:28.679
at those equations back in the nineteen
twenties that produced this idea of as you

554
00:49:28.719 --> 00:49:32.840
said, a hypothetical object theory ez
to be a potential mode of time travel,

555
00:49:35.119 --> 00:49:43.960
and it's because of its effect on
the closure of off space time.

556
00:49:44.039 --> 00:49:47.880
You might put it that way.
The gravitational potential is such that you get

557
00:49:49.960 --> 00:49:54.079
instead of space time being a nice
you know, a nice lattice of stuff,

558
00:49:54.119 --> 00:49:57.159
a bit. I always think of
space time as being like one of

559
00:49:57.199 --> 00:50:01.800
those climbing frames that you find in
kids kids parks, the old fashioned ones.

560
00:50:01.800 --> 00:50:06.079
Anyway, they're not like that anymore. But they were just a you

561
00:50:06.159 --> 00:50:09.840
know, a regular set of things
are arranged in right angles, and it

562
00:50:09.960 --> 00:50:15.519
gave you a three dimensional structure that's
you know, that's normal space time.

563
00:50:16.639 --> 00:50:21.199
Ben space time is when somebody every
stands on one of those and that's what

564
00:50:21.920 --> 00:50:27.159
that's what the what The equations of
relativity shows that when you put matter in

565
00:50:27.239 --> 00:50:30.559
there, they bend. But when
you think of all this happening around an

566
00:50:30.599 --> 00:50:37.639
infinitely long cylinder, you get the
the structure of space itself closes on its

567
00:50:37.840 --> 00:50:40.000
on itself. If I can put
it that way so that you you've got

568
00:50:42.119 --> 00:50:45.400
a way of moving around in time
as well as space, that's the that's

569
00:50:45.480 --> 00:50:52.440
the idea. There's there's also a
phenomenon called frame dragging, which we know

570
00:50:52.559 --> 00:50:58.159
is a real phenomenon of relativity.
It's there was certain I forgot which spacecraft

571
00:50:58.239 --> 00:51:05.039
it was. Won't come back to
me. There was one particular spacecraft that

572
00:51:05.440 --> 00:51:09.599
was put into orbits around the Earth
that was designed to demonstrate that the Earth

573
00:51:09.639 --> 00:51:16.960
as it rotates drags space time with
it. This frame dragging phenomenon. So

574
00:51:17.039 --> 00:51:20.679
we needed to give a story on
that a while back. I think we

575
00:51:20.760 --> 00:51:23.280
did two. Yeah, I think
we did two. And so the cylinder

576
00:51:23.320 --> 00:51:29.440
itself is it's spinning along its long
axis, will create this frame dragging effect,

577
00:51:29.960 --> 00:51:35.719
warping space time in such a way
that you might be able to travel

578
00:51:35.760 --> 00:51:39.400
backwards in time. That's the bottom
line, okay, And so I forgot

579
00:51:39.599 --> 00:51:45.159
what Martian's question was. What would
a spacecraft look like it was going backwards

580
00:51:45.159 --> 00:51:49.679
in time? It probably just like
playing a movie in reverse. Probably.

581
00:51:52.119 --> 00:51:57.079
Sadly, the boot was put in
by a number of people, including a

582
00:51:57.159 --> 00:52:07.480
follow called Stephen Hawking. He through
a relativistic argument the idea of a tipless

583
00:52:07.559 --> 00:52:12.480
cylinder, suggesting that it would never
it would never be able to be built,

584
00:52:13.159 --> 00:52:16.800
which means you couldn't terraform one.
Basically, that's right, it's forgotten,

585
00:52:17.199 --> 00:52:21.559
forgotten. Terr reforming was at the
heart of Martin's question, as it

586
00:52:21.559 --> 00:52:25.239
always is. And terr reforming a
tipless cylinder, Yeah, that would be

587
00:52:25.280 --> 00:52:30.239
tricky. That would be very tricky. You know, you're a sci fi

588
00:52:30.400 --> 00:52:35.679
writer, Martin, I'm just do
it, just do it. It can

589
00:52:35.760 --> 00:52:38.639
do anything in science fiction. Well, you know that. You know that's

590
00:52:38.760 --> 00:52:44.079
the candise, Sandra you doing.
I'm currently reading the latest John Birmingham series.

591
00:52:44.159 --> 00:52:47.320
Johnson, Oh yeah, an English
author, but he's Australian based and

592
00:52:47.440 --> 00:52:53.880
he's just released He always releases books
in threes. All his stories have three

593
00:52:54.079 --> 00:52:59.840
volumes, and I mean halfway through
the second of three books in his latest

594
00:53:00.000 --> 00:53:05.559
series, and it's a it's just
a classic outer space war story, which

595
00:53:05.639 --> 00:53:09.639
is he he hasn't done ones like
that before. He's done other really interesting

596
00:53:09.719 --> 00:53:15.400
stories about monsters coming out of other
dimensions and eating humans. And he did

597
00:53:15.480 --> 00:53:17.719
one about a big blob that came
from out of space and wiped out half

598
00:53:17.760 --> 00:53:22.920
of America and half of Canada and
what happened to the world. That one

599
00:53:22.039 --> 00:53:25.159
was called Without America. He writes
brilliantly, and I'm really enjoying this,

600
00:53:25.719 --> 00:53:31.199
this latest series, which is he
hasn't released the third book yet, but

601
00:53:31.239 --> 00:53:36.159
it's due out this year, so
I'm slowly reading the second one so I

602
00:53:36.199 --> 00:53:38.639
can get straight into the third one
when it comes out. It's great stuff.

603
00:53:40.960 --> 00:53:45.400
Once did a gig with him.
Oh did you in Brisbane? Yeah?

604
00:53:46.239 --> 00:53:51.000
Yeah? I love his writing style, really do. My favorite character

605
00:53:51.119 --> 00:53:55.960
of his is super Dave, Super
Dave. Yeah, and then that series

606
00:53:57.039 --> 00:54:01.320
has since been recalled renamed the Super
Day Series because it sort of took over.

607
00:54:02.840 --> 00:54:06.559
So we've got to look out for
the super dunk theory. Oh go

608
00:54:07.239 --> 00:54:13.559
superdum series. Enough. If you're
listening, John, this is it super

609
00:54:13.599 --> 00:54:16.320
dumply Yeah, yeah, yeah.
Give me put in a kind word to

610
00:54:16.400 --> 00:54:22.599
your publishers for me. That'd be
nice. That will never happen. All

611
00:54:22.719 --> 00:54:24.760
right, Thank you very much,
Martin. Always good to hear from you.

612
00:54:25.280 --> 00:54:28.039
We're going to wrap it up there, Fred, I think we got

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00:54:28.079 --> 00:54:30.719
through a fair bit today. But
again i'll remind people, because we've now

614
00:54:30.800 --> 00:54:35.199
exhausted quite a few of our questions
to send them in via our website,

615
00:54:35.679 --> 00:54:38.679
Space nuts podcast dot com. Click
on the AMA link to send text or

616
00:54:38.679 --> 00:54:42.920
audio questions, or just click on
the tab on the right hand side of

617
00:54:42.960 --> 00:54:45.960
the homepage where you can send audio
questions. Don't forget to tell us who

618
00:54:46.000 --> 00:54:49.840
you are and where you're from.
You can record your questions via any device

619
00:54:49.920 --> 00:54:53.079
with a microphone. Basically, it's
that simple. And check out all the

620
00:54:53.119 --> 00:54:57.159
other stuff on the website while you're
there, Fred, thank you as always.

621
00:54:57.239 --> 00:54:59.800
It's a great pleasure, and yeah, it's good to get through some

622
00:54:59.840 --> 00:55:04.280
of the questions and hear from the
audience. Indeed, the top five or

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00:55:04.360 --> 00:55:08.519
sence than we did sounds great.
Thanks Andrew, we'll see you next time.

624
00:55:08.599 --> 00:55:13.239
Indeed we will Fred Watson, astronomer
at large part of the team here

625
00:55:13.559 --> 00:55:16.400
at Space Nuts. And thanks to
Hugh in the studio who actually turned up

626
00:55:16.400 --> 00:55:21.320
for work today, and from me
Andred Hunkley, get you on the very

627
00:55:21.400 --> 00:55:25.639
next episode of Space Nuts. Bye
byepauts. You'll be listening to the Space

628
00:55:25.719 --> 00:55:35.039
Nuts podcast available at Apple Podcasts,
Google Podcasts, Spotify, iHeartRadio, or

629
00:55:35.119 --> 00:55:38.679
your favorite podcast player. You can
also stream on demand at bites dot com.

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00:55:39.239 --> 00:55:44.199
This has been another quality podcast production
from nights dot com.