#416: Cosmic Conundrums & Astral Assemblies: Tackling the Universe's Toughest Questions

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Hi there, Thanks for joining us
on this Q and A edition of Space

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Nuts. Andrew Dunkley here, your
host. Hope you're well. Coming up

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on this particular show, we're going
to be focused on black holes. We've

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got two questions independently that basically ask
a similar thing about black holes and magnetic

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fields, and I think we've had
similar questions in the past, so we'll

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tackle that one probably again. We're
also going to look at different kinds of

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stars, how many of each there
might be, and do those proportions agree

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across galaxies and if it's different.
Why personal projects? Someone wants to know

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what Fred's favorite personal project has been
over the years. Oh gosh, that

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goes back well when Galileo and I
were sitting on the beach. You know,

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we'll find out. And Rusty has
asked why fog bows are white.

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That's all coming up on this edition
of Space Nuts fifteen, Channel ten nine

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ignition sequence Space Nuts three two.
Nice as when I report it real good

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And here he is Professor Freedwards,
an astronomer at large. Hello Fred,

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Hello, I believe when you were
sitting on the beach with Galileo that you

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were talking about the gravity of world
affairs. We were drinking a cup of

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gravity each. Actually it was really
nice. Ye, good stuff, that's

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good stuff. How are you going? You're good? Yes, well,

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thank you. I'm good to see
you too. I hope you're well as

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well and taking your gravity seriously.
I think I have we have to sack

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our laundry. We're both wearing the
same shirts as last week. So it's

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a bit of a worried. It
is shocking, isn't it. Yeah,

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I should have it's not good.
Yeah, well we could. We could

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stretch that joke for a long long
time, but we're not going to.

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No, that's probably not really worth
it, and probably nobody would have noticed.

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I did not mention, Probably not
the lady. The ladies would probably

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notice before the men. My wife
notices things about my attire that I don't

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even think about. So yes,
it's another story that just shows they're so

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much more fashionable than we are.
Shall we do some questions for no,

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let's just at the show. That's
probably well, yeah, just that was

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quick and easy. Until next time. How about we talk about black holes

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and magnetic fields. This is a
question from Robert, and I'll follow it

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up with a text question. We
got from Lachlan. Here we go,

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Andrew, this is Robert from the
Evidence. I have a question about black

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holes on my favorite subjects. This
is not dark matter, right. Apparently

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black holes do not have a sucking
everything everything that's something to the black hole.

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However, we do see these enormous
jets being ejected from quasards one hundreds

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of thousand bagsish long. Obviously they
do have some sort of poles. Of

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these poles. The only time I
see that the reality is with neutron stars,

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white Horse. The Tory stars a
sort of thing and it's always due

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to a magnetic field. So how
can this be? Maybe black holes do

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have magnetic field, and you know
the sertains that are disc around it would

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be able to create this thing.
However, that would not be responsible for

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poles on the object itself, I
would think. However, maybe I'm wrong.

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So what do you think, guys? The MA they of any hole

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in it? Where is it a
hole in one? I'll hear it,

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uh jokes jud jokes from all corners. Thank you, Robert. And in

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conjunction with that, we've got a
text email, a quick one from Lachlan

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saying, is black hole radiation the
electromagnetic field. This SEMs to be a

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point of contention. We get a
lot, We've had a lot of questions

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about black holes, but this one
seems to come up semi regularly for it.

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Yeah, it does, and it's
kind of connected with if I remember

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rightly, it's called the no hair
theorem, which I really like, actually

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the no hair theme I'm sure you
do, which is that there's only a

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few parameters that you can learn about
a black hole. And I did write

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about the no yeah, no hair
theorem in Cosmic Chronicles. I should read

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it again and find out what I
said. But yes, because you know,

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there's just a very few parameters,
and the idea of magnetism is that

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magnetism isn't one of them, which
is kind of what Robert is alluding to.

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So if you have, you know, no hair black the fact that

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there's no hair there tells you that
there's no magnetism. However, however,

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clearly do have magnetic fields, because
that is what focuses the jets of radiation

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and material that are exactly the cause, as Roberts alluded to, of quasars.

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Active galaxies Delinquent galaxies are sometimes called
them because they're all youthful galaxies.

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We're looking back in time a long
way and see the seeing these quasars.

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So there is clearly some way in
which magnetism can occur. And you basically

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what you do to get the magnetic
field of your black hole is you rotate

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it. So it's got to be
a rotating black hole and give it an

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electric charge. And those two things
together, an electric charge and angular moments,

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which is just a fancy word for
rotation, produce what is known as

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a ker Newman black hole k double
R Newman black hole. A curR black

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hole is one that routates. I
think a black hole is probably one with

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electric charge. One with both of
those things is a kur Newman black hole,

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and it does have a magnetic diephole, which tells you it's got a

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magnetic field. So yes, a
black hole can have a magnetic field,

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all right. And Laplin's question,
is black hole radiation the electromagnetic field that's

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somewhat different angle on it? It
is. That's partly true because what happens

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is that you know, you've got
a Kerr Newman black hole that's got a

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strong magnetic field, it's got an
accretion disc of material around it, stuff

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that's been gobbled into the black hole. That material is swept up or some

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of it is swept up by the
magnetic field and squirted out at the poles

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of the black hole, the rotation
poles to make these jets of material,

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which themselves also generate radiation because you've
got highly energetic particles moving through you know,

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a medium, non vacuum medium.
And so yes, the jets are

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basically the radiation that arises because of
the magnetic field of the black hole.

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Question. I think so yes,
but I don't really know. We just

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get so many questions about them.
I note that there's been a new image

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released of a black hole at which
was revealed in the last few weeks.

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Actually, so they've got a bit
of a better understand ending of it from

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the image of environment and that was
I think was James Webb image, if

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I remember rightly. But yeah,
that's we're starting to get more and more

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information about them, so maybe more
of their secrets will start to be unraveled.

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Or was it Sagittarius a star that
we're talking about. There was one

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that that published information about earlier this
year. It was the twentieth of March

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and it is Sagittarius, so there
is a marvelous rendering. And again it

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comes back to something we talked about
in the last main issue of Space Arts

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about polarized light. How you detect
magnetism via polarized light. The Event Horizon

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Telescope collaboration, which looks at the
structure of black black hole accretion discs,

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has indeed detected the polarization of that
doughnut shaped disc around the black hole at

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the center of our galaxy. And
it's a picture that you can find online.

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It's pretty easy to find, but
dated day March this year. Space

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dot com is a good place to
start, but there are plenty of articles

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on it, but space dot com. Thanks Robert and thanks Lachlan. I

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hope we helped you out there.
Let's move on to our next question.

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This one comes from Pete. Hello, Fred and Andrew. This is Pete

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Alinga from Sunny Sheffield in the UK. I have three questions for you,

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all related to the mnemonic obi A
fine Girl kiss Me, which I use

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to remember the different types of stars. Question one, what are the proportions

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of these star types in the Milky
Way? Question two? Do these proportions

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hold through for all galaxies. Questions
three, If the proportions are different across

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the universe, what does that tell
us? Thank you for the great show,

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which is all the better for splitting
out the Q and AS into a

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separate recording All the best, Eat
Manager Pete. It is lovely to hear

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from you. Thanks for the endorsement
on doing two shows a week instead of

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one. It seems to be well
accepted, so that's good. Different kinds

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of stars, yes, we know
there are. How many of each in

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the milky way? Do those proportions
correlate across galaxies? And if they're different?

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Why? I think that's a price
of his entire question load. It

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is, that's right, so you
know what we're looking at here is the

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be a fine girl kiss me is
well known actually these days is also be

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a fine guy kiss me. It
was a mnemonic that was conjured up back

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in the day for the what we
call the spectral classes of Just a minute,

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let me deal with this. I
find the phone. That's no good.

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I'm not going to say that's.
Get rid of that. Yes,

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sorry about that. I don't know
who that was from somewhere, probably trying

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to sell you cladding or solar pals
while they're in Queensland, so it could

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be either of those. As you
can tell you, I do apologize for

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that, apologize to all our listeners. I meant to put the phone on

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silent and I clearly forgot. I
actually forget to do it on the radio

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sometimes, so yeah, I can
sympathize, Yeah, but I won't.

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So we were unless it was somebody
responding to my exhortation or be a fine

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girl, kiss me. It could
have been that, I guess, coming

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in by phone. But it's a
mnemonic for the spectra classes of stars.

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And the reason why it's so totally
counter intuitive. You know why isn't it

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in straightforward alphabetical order, is because
it goes back to the very early days

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at the beginning of the last century
of people doing this spectral classification working out

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what the different kinds of spectra of
stars meant. So when you look at

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the spectrum of a star, you
get this barcode of information and they're different,

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and that we now know a lot
of the difference depends on temperature,

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some of it depends on age.
These are all factors that are in that

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and so they did classify them originally
A, B, C, D,

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E, F, G, et
cetera. And then eventually it was worked

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out what it was that these things
were telling you. And it's now in

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temperature order going downward, so O
stars are the very very hot ones surface

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temperatures twenty thirty thousand degrees kelvin down
to the M stars the me of the

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mnemonic so ob A f G k
M M stars are the red dwarfs with

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surface temperatures region of three thousand degrees
kelvin, that sort of sort of temperature.

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And so that distribution has been you
know, we know that those are

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the classes. And Pete tasking an
ip fellow Yorkshireman, Pete asking about what

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the relative numbers are of those,
and it's pretty easy to find them on

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the interweb. I just d good
so you can answer the question. The

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bottom line is, you know the
essentially that obfgk M is out the A.

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I think it is an order of
decreasing temperature and its order of decreasing

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numbers, sorry, increasing numbers,
because the stars are the rarest and the

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M stars are the commonest. In
fact, they're by far theless common type

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of stars in our galaxy. Sou
and as as is is as a G,

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so they sort of rank in the
middle to higher end of numbers.

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Yes, but they're nowhere near as
common. M stars are ms accounting for

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seventy six and a half percent of
all stars, and G is seven point

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six, so it's a lot less, whereas O stars are rare still aren't

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they point zero zero zero zero three
percent of all stars? There you go,

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So that's the perfect answer to the
question. You see, you don't

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really need me, however you might
need yes, yes, which was about

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whether you know this. The same
is true for other galaxies, and there

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are subtle differences. Basically it's the
same distribution, but there are some subtle

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differences. And in Pete's next question
was if there are differences, what causes

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them, and it's things like differences
in the amount of metals which are in

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those stars. So metallicity the amount
of basically the amount of iron in a

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star, although as you know,
Andrew, astronomers think of everything except hydrogen

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and helium as being a metal,
which ismical, but anyway, so the

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metallicity can vary in a galaxy and
that would give slightly different numbers, but

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really the marginal by far the communist
types of stars in the universe or Amy

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stars, these dwarf stars type the
am of kiss me indeed, so yeah,

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easy to find on the internet if
you want to have a look at

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those various star types and the well, all these statistics, their vital statistics,

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I think would be the best way
to describe it. Pete, thank

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you. I love those questions because
they sort of get into the nuts and

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bolts of stars and it sounds like
it's pretty much the same across galaxies,

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give or take, which is good
because that would have been if they weren't,

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it would have been a much longer
explanation. This is space Nuts.

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Andrew Dunkley here with Professor Fred Nuts. Okay, Fred, let's move on

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to our next question, which comes
from Michael. I. Just Michael from

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Kent to the UK. Just a
question you guys. If there was a

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project that you could have worked on
past or president, what would it be

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more exclusively Professor Watson, what projects
stood up for you the most that you've

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worked on and why enjoy your show? Guys? Thank you so much.

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Maybe a bit selfish, but I
enjoy your long episodes because it helped makes

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my micro shifts a lot of you. Thank you so much and enjoy it.

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Thank you, Michael. We just
said someone saying we love he you

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split them up, and now Michaels
saying I like them when they're long.

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You could save it up and just
running back to back. It would be

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my advice because you can do that. Personal projects, I mean for me,

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I mean I work in radio and
so I haven't had direct involvement with

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astronomy except with Fred, but gosh, and I think for me it'd be

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more space, space science related.
I'd want to be working on maybe a

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mission to the Moon. I would
love to have been involved in if I

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was old enough and clever enough working
on the Apollo missions, actually being hands

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on getting those missions off the ground. If there was some way of turning

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back the clock and being in the
right place at the right time, that

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would be something I would have adored
working on, probably because it was so

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very much synonymous with my childhood.
It all started when I was pretty well.

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When I was born, I could
send home from school to watch the

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moonwalk Apollo eleven Moonwalk on TV,
which happened in the early afternoon our time,

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if I recall correctly, on my
families black and white TV. That

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to me was probably one of the
most inspiring things that I saw as a

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kid, and it's still with me
today. Going down after the missions to

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Parliament House in Canberra with my family
on holiday and walking into the foyer and

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they had a glass cabinet, a
glass box and inside the box was a

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little claw, and on the top
of the claw was a rock. And

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that was a rock they brought back
from the Moon. And I was absolutely

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mesmerized by that. I couldn't believe
that I was seeing a rock from another

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world. It was just a piece
of basshold, but that's beside the point.

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There was a piece of another world, and that just blew the lid

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off my brain. So if I
could do anything again, or do anything

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in the past astronomy, space science
related, that would probably be one that

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I would want to work on,
a bit more sort of nuts and bolts

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than something Fred might be about to
talk about. But I went over and

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I saw the Apilow eight control room
that they set up in Florida at the

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NASA base there, got to see
the Satin five rocket hanging from the ceiling,

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got to see Neil Armstrong's uniform,
his spacesuit. Yeah, all of

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that is it's probably what tickles my
fancy most of all in terms of space

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sen So that would be it for
me. Michael Paul Shaw. What about

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you, Fred, Well, yeah, I mean I endorsed all that completely,

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but just to come a little bit
further down to earth, if I

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may. I do have friends who
have worked on projects which really we're milestone

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projects, and one of them is
the Kirby Mission, the Cosmic Background Explorer,

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which was a base mission designed to
measure for the first time the cosmic

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microwave background radiation. It's that was
I think in the nineties. Yes,

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it was the nineties where that was
happening. It's been superseded by since then

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by W. Matt the Wilkinson Microwave
and Issotropy Probe and PLANK and a European

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spacecraft that measured the cosmic microwave background. So what we're doing here is putting

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a satellite into space to look for
the after glow of the Big Bang,

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which is a pretty neat thing to
do, you know, the cosmic wallpaper,

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the thing beyond which we can see
because we're looking back in time so

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far that we can see the glow
of the Big Bang, and it's got

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this structure on it, which was
imposed on it by sound waves in the

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early universe. That's the really,
you know, almost spooky bit of this.

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But the colleague guy had who worked
on that, I always thought,

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what a way to start your career. I think it was his PhD topic.

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He was part of the Kobe team, and he did a lot of

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work on that. He's now an
astrobiologist, so he changed tech completely.

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And then the other one, it's
a similar sort of thing and epoch making

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discovery and maybe there are two.
Actually yes, One would be imagine being

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part of the team that first detected
gravitational waves back in twenty fifteen, Attigo.

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You know, you really be absolutely
blown away by the fact that for

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the first time you've detected a gravitational
wave from impact. I think it was

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neutron star collisions that first one,
if I remember rightly, it was.

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It's a date that I can easily
remember, fourteenth of September twenty fifteen,

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because that's Marny's birthday. So it's
stuck in my mind that it was on

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her birthday. And the other one
guests similar because it involves a huge,

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huge collaboration. It would have been
great to have worked on the event horizon

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telescope to produce that very first picture
of a black hole event horizon, the

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one from eighty seven just a few
years ago as well. So those are

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really big ticket projects which it would
have been great to work on. The

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big projects that I've worked on,
in a way, the one that I

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had most to do with in it
was actually my project which was developing wide

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angle spectroscopic instruments for the United Kingdom. Siret Telescopture's a wide angle telescope one

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point two meter diameter aperture, and
I built three generations with a lot of

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help, of course, of fiber
optic instruments, three or four. It

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was three. The fourth generation was
actually nothing to do with me, but

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I was kind of cheering it on. So what that meant using this fiber

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optic technology was that you could measure
the spectrum of many objects simultaneously, up

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to one hundred and fifty in the
end, and we in fact it was

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four generations. The fifth generation was
the one I wasn't involved with, so

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I did a lot of work on
this. The fourth generation one we did

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surveys of stars in our galaxy,
half a million stars and also surveys of

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about one hundred and sixty thousand galaxies. We made a map of the nearby

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universe with these galaxies. And those
two surveys were also big projects that I

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worked on. One was called the
sixty f Galaxy Survey sixty FGS, which

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wound up actually in two thousand and
three. The other was the RAVE Survey,

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00:24:47.559 --> 00:24:52.720
the Radial Velocity Experiment, which wound
up two well, they observing wound

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up in twenty thirteen. So they
were big projects which gave me a lot

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00:24:56.599 --> 00:25:00.119
of a lot of anks, I
can tell you. That's why i've hairstyle

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here. But nevertheless, they were
also very very rewarding and you know,

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00:25:06.440 --> 00:25:08.559
made me think. I think they
did quite a lot for my astronomical street

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credit booth of them. Yeah.
Indeed, another one I remember, and

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00:25:14.960 --> 00:25:18.640
you and I did a little documentary
piece on this was the two degree field

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00:25:19.119 --> 00:25:25.720
instrument that that was a big sort
of leap forward and it was a sort

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00:25:25.720 --> 00:25:29.880
of an add on to the existing
telescope as far as I remember, wasn't

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it, Fred. It's a bit
like it is add on to the Angle

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00:25:33.720 --> 00:25:38.480
Australian Telescope HPPY that we're talking about
in the last episode. Yeah, yeah,

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yes, thank you, Michael.
I hope that filled the breach in

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terms of personal projects that we would
love to have worked on. Final question,

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Fred comes from Rusty and Johnny Brook. I've paraphrased this because Rusty asks

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00:25:53.079 --> 00:26:00.200
questions in chapters, but I'll break
it down. Why a fog bow's white?

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00:26:00.279 --> 00:26:03.920
Now? When I first read his
question, I thought, what's a

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00:26:03.960 --> 00:26:07.359
fog bow? I'd never heard the
term before. I know that sounds strange,

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00:26:07.359 --> 00:26:12.440
but I've never heard a reference to
a fog bow before. So I

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00:26:12.440 --> 00:26:15.519
had to have a close look at
his photo and try to figure out what

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00:26:15.519 --> 00:26:19.400
he meant. And he's talking about
a rainbow effect in fog. But they're

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not a rainbow because they're white.
They're just white. He is suggesting that

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00:26:23.880 --> 00:26:29.119
it's water droplet size that might be
a factor here. What are we talking

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00:26:29.160 --> 00:26:33.799
about, Fred, Yeah, So
sunlights lighting up a bank of fog,

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and I'm supposed you've never seen one, because I used to see them a

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00:26:37.200 --> 00:26:40.960
lot when I was driving to your
town back in the day when I used

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00:26:40.960 --> 00:26:45.759
to commute from kinder Burbon to talk
on the NBC. So sunlight, it

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illuminates a bank of fog, and
if you're at a position where the sun's

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00:26:51.559 --> 00:26:56.920
behind you, it forms what amounts
to a rainbow. But exactly as you

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say, the colors are washed out. They're just white. Now, Rusty

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00:27:03.079 --> 00:27:07.440
did send an image of a fog
bow, which was a beautiful image,

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00:27:07.720 --> 00:27:10.599
and yes it's white, but if
you look carefully, you can just see

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00:27:10.599 --> 00:27:14.720
a slight red tinge on the outside
of it and a slight bluish tinge on

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00:27:14.759 --> 00:27:17.759
the inside of it. And that's
Those are the colors that you see in

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an normal rainbow. So it's a
kind of rainbow, but with the colors

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00:27:21.519 --> 00:27:26.880
washed out. And that's exactly what
happens. What's happening, and Rusty is

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00:27:27.039 --> 00:27:33.720
perfectly right. It's called it's all
to do with droplet size. So fog

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bow droplets are much much smaller than
rain drops that form a rainbow. The

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raindrops forming a rainbow could be half
a millimeter in diameter. The ones for

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00:27:42.440 --> 00:27:48.400
a fog bow much smaller. It's
an aerosol almost where you're talking about your

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00:27:48.440 --> 00:27:52.359
fifty microns or something like that,
rather than half a millimeter, so much

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00:27:52.359 --> 00:27:56.359
smaller, so there is a rainbow
effect. Rainbows are caused by refract refraction

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and dispersion of light in a globe
of water, dispersion being the spreading out

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00:28:02.880 --> 00:28:07.200
into the spectrum that happens in a
fog boat droplet as well, but because

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00:28:07.240 --> 00:28:12.519
they're so small, it's swamped out
by another effect called diffraction, and diffraction

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00:28:12.799 --> 00:28:15.720
is to do with the wave nature
of light. Because these things are so

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00:28:15.759 --> 00:28:19.000
small, you got to take the
fact that light is a wave motion into

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00:28:19.039 --> 00:28:23.359
account. And what it does is
it just washes out the colors. So

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00:28:23.680 --> 00:28:27.880
every color, rather than being a
single color in a specific part of the

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00:28:27.960 --> 00:28:33.359
rainbow, just gets washed out to
be much broader. So the colors are

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00:28:33.359 --> 00:28:37.720
all there, but they're swamped by
each other until they become white, exactly

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00:28:37.799 --> 00:28:41.160
like you know, if you're pushing
it back through a prism, all these

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00:28:41.160 --> 00:28:45.119
colors they will turn white. That's
not the reason. It's because of diffractions

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00:28:45.119 --> 00:28:48.200
spreading out the being, but they
look white. So yeah, a lovely

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00:28:48.240 --> 00:28:52.880
photograph from Rusty. We should put
that one on the website. I think

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00:28:52.880 --> 00:28:56.720
I will send it to Hugh so
that he's got something to do. Yeah,

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00:28:56.759 --> 00:29:03.880
I'll do that, Yes, yes, thanks Rusty, and always good

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00:29:03.920 --> 00:29:10.960
to hear from you. Rusty often
sends photos through of his astronomical images and

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00:29:11.319 --> 00:29:14.319
it gives me photographic tips. I
haven't tried them yet, but I will

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00:29:15.000 --> 00:29:17.920
when I get into some dark space. It's a bit too much light around

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00:29:17.960 --> 00:29:22.400
my new place, so I don't
have much luck with astrophotography in my backyard.

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00:29:22.440 --> 00:29:27.400
But forgbos, yes, I can't
believe I've never heard that term before.

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00:29:27.559 --> 00:29:30.480
Maybe I was just so ignorant to
it it never stuck in my brain,

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00:29:30.519 --> 00:29:36.599
which is basically my entire education.
So thank you, Rusty. Lovely

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00:29:36.640 --> 00:29:38.720
to hear from you, and Michael
and Pete and Lachlan and Robert. Thanks

335
00:29:38.759 --> 00:29:41.559
for sending your questions in, and
don't forget. If you've got questions,

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00:29:41.599 --> 00:29:45.599
we'd love to get them from you, send them in right now. We'll

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00:29:45.640 --> 00:29:51.079
wait or we'll look later. You
can send them via our website, spacenuts

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00:29:51.200 --> 00:29:55.440
podcast dot com or space nuts dot
io. Just click on the links on

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00:29:55.480 --> 00:30:00.240
the page and you can send us
audio or text questions. Text questions through

340
00:30:00.240 --> 00:30:04.599
the AMA tab, audio questions through
AMA and the send us your audio question

341
00:30:06.480 --> 00:30:11.440
on the right hand side under that
weird purple color. That's it, Fred,

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00:30:11.480 --> 00:30:14.400
Thanks again so much, lovely to
catch up. We'll see you soon,

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00:30:14.960 --> 00:30:18.880
so great. Take care on you
you too, Fred Watson Astronomer at

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00:30:18.920 --> 00:30:22.799
Large, and thanks to Hue in
the studio for not asking us any questions

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00:30:22.880 --> 00:30:26.759
at all ever, and from me
Andrew uncle, it is goodbye until next

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00:30:26.799 --> 00:30:32.440
time on Space Nuts see you then
bye bye snus. You'll be to the

347
00:30:32.519 --> 00:30:40.599
Space Nuts podcast available at Apple Podcasts, Spotify, iHeartRadio, or your favorite

348
00:30:40.640 --> 00:30:45.119
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349
00:30:45.200 --> 00:30:49.640
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