Waves, Signals, and Cosmic Aromas: A Q&A Journey Through Space

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Andrew Dunkley: Hello again. Thanks for joining us on a Q and

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A edition of Space Nuts, where we talk

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astronomy and space science and we

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endeavour to answer, uh, questions from

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our audience. We've got a few good questions

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today, unlike all the bad ones we had

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previously. Uh, we're going to talk about

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radio telescope imagery. What does that

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mean? How does it work? I don't understand.

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And that's just me. Um, we also

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are going to be talking gravity waves. Now,

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I'm not sure if it's gravity or

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gravitational. They are different things. Uh,

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and also, uh, sounds and smells in space.

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What would they be like if you could stick

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your schnoz beyond our atmosphere? We'll talk

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about all of that on this edition of space

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nuts.

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Generic: 15 seconds. Guidance is internal.

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10, 9. Uh, ignition

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sequence start.

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Jonti Horner: Space nuts.

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Generic: 5, 4, 3, 2, 1. 2, 3,

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4, 5, 4, 3, 2', 1.

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Jonti Horner: Space nuts.

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Generic: Astronauts report it feels good.

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Andrew Dunkley: He's back again. He is Professor Jonty

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Horner, professor of Astrophysics at the

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University of Southern Queensland. Hi, Jonty.

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Jonti Horner: Good afternoon. How are you going? I am well.

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Andrew Dunkley: Good to see you again.

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Jonti Horner: It's good to be back. I think I'm going to be

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doing a lot of. I'm not sure, but today I

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think we've got questions that are a little

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out of my area of expertise. Um, I'd always

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like to flag up at the start when things are

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less my field because we don't all know

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everything. And it's good to, rather than

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pretend, good to be open about what I do and

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don't know.

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Andrew Dunkley: Fair enough.

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Andrew Dunkley: But, uh, we'll do our very best. I

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got the easy part. I just get to ask the

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questions.

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Let's, uh, get straight to our first one.

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And this one, uh, asks how is

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a photographic image produced from a radio

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telescope when all they are receiving is

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radio waves and not an optical image through

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a telescope lens? Uh, that's, uh,

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from Thomas in Canberra. He's thrown in a

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supplementary Monty Python, Monty Python

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style question. Were the pyramids built

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by aliens? Does that sound

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fair enough?

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Andrew Dunkley: Uh,

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Andrew Dunkley: horrible, dad joke.

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Andrew Dunkley: Horrible.

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Jonti Horner: But if you want to keep your

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Andrew Dunkley: razor sharp, I did see an article only

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a few days ago about, uh, a new theory into

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the building of the pyramids. But we went to

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Egypt a few years ago and they are, uh, quite

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adamant that, um, not only were they built

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by humans, they were built by

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what you would call contractors. They were

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not slaves. The people that built the

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pyramids, according to the locals, were

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actually employed.

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Jonti Horner: Yeah, lots of discussion of that. My partner

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Ness, is an avid history buff and

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also Likes to watch a bit of TV when she's

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trying to relax, to go to sleep. So I'm m

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constantly seeing archaeological

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documentaries and things like that. And she

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loves the Egyptians. So I've seen lots and

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lots of documentaries talking about this. And

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it turns out, if what I've seen in these

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shows can be believed, that it was actually

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fairly prestigious and fairly good working

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conditions to be one of the contractors

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working on the pyramids kind of building

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that. So.

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Andrew Dunkley: Yeah, I heard that too. Yes, exactly.

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Jonti Horner: Crack the big whips and all the rest of it.

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Andrew Dunkley: But yeah, yeah, no, it's fascinating

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history. Wouldn't you love a time machine

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just to go back and go, ah, uh, look.

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Andrew Dunkley: Yeah,

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Andrew Dunkley: now that we're seeing it, it looks easy.

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Jonti Horner: Uh, absolutely. I mean, I probably end up

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being really kind of busman's holiday though,

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with the time machine and going back to

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different astronomical events and think like,

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trying figure out if Caesar's Comet was

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actually real, you know, and, you know,

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trying to see if there were multiple sun

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grazing comets visible with the naked eye in

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daylight in I think it was 363 A.D. so

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I'd probably end up picking myself an

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astronomical holiday tour, um,

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not getting distracted by all the kind of

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human history stuff.

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Andrew Dunkley: Yeah, fair enough. I mean, you go nuts

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thinking about things to go back and see.

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Absolutely.

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Jonti Horner: Or going forward. I've said a few times that

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given the predictions we talked about last

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year, that Comet Duchesso, Comic

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Linkenberg, will return in the year 2097.

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That could well be the best comet of this

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century. I'd quite like to see it, but

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unless I am fortunate enough to reach 119

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years old, I think it unlikely. So,

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you know, time machine would be welcome.

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Andrew Dunkley: Yeah, it would. I'm working on it.

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Uh, so let's go to the first part of the

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question. Uh, how is a photographic image

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produced from a radio telescope when

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all they receive is radio waves and not an

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optical image through a telescope lens? Yeah,

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I've got to admit, this one confuses me a

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bit.

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Jonti Horner: We could say the same for infrared. We could

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say the same for gamma rays or X rays or for

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optical photographs. Right. So all of those

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different forms of radiation I just mentioned

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are different, uh, parts of the

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electromagnetic spectrum. So they're

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fundamentally the same thing but with

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different wavelengths in just the same way

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that red light and blue light are

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electromagnetic waves, but blue has a shorter

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wavelength and red has a longer wavelength.

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And um, I've got an astro photo behind me of

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the Helix Nebula. If I had a camera that was

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more sensitive to infrared, I would have

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picked out some slightly different features

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there because there is radiation coming in of

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different wavelengths. The way it

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works with a radio telescope or the way that

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it works with an M infrared detector or

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whatever is, you've got a detector

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that can detect radiation of that

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wavelength. Um, with an optical photo,

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you have a DSLR camera or a CCD camera that

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is sensitive to optical light and

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you get photons hitting the detector and

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creating electrons that are countered in the

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same way. For a radio telescope, you have a

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detector that is sensitive to radio waves

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and when photons of the right energy hit the

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detector, they create electrons and they get

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countered. So what happens is you've got your

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radio telescope that can look at a patch of

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sky with some level of

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resolution and some telescopes have

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better resolution and some have blurrier

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vision linked to the size of the telescope.

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Typically, the bigger a telescope is, the

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better its resolution will be. For optical

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telescopes, the atmosphere puts a cap on

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that. Uh, unless you can do things to filter

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it out at about 1 arc second, very

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roughly, the turbulence of the

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atmosphere is a bit of a pain. But in theory,

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if you could take the atmosphere away, you

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would be able to see smaller things on the

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sky with a 10 metre diameter telescope than a

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1 metre telescope in the optical. And there's

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a mathematical relation for this that we

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teach our students at undergrad level. The

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resolution of the telescope, so what the

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smallest thing it can see is, if you ignore

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the atmosphere, if you look purely on the

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physics of it, is related to

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the diameter of the telescope. A bigger

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telescope will see a smaller resolution, but

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it's also related to the wavelength. So if

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you've got two telescopes of identical size

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and one's looking at optical and one's

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looking at radio waves, the radio waves are

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much longer wavelength, so the resolution of

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that telescope will be much lower.

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So radio telescopes of the same size as an

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optical telescope will get a blurrier image,

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but we can build radio telescopes much

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bigger. So there's swings and

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roundabouts there. But effectively what

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happens is you've got your image

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of the sky, the telescope looking at a patch

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of sky, and you've got a detector that

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counts the amount of radio waves

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impacting upon it in the form of photons

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impacting upon it. And that gives you a

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measure of how bright that bit of sky is.

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Now, if you've got multiple pixels, you can

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see different bits of that, uh, image

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in the same way as with a normal camera. One

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way. I think that this used to be done back

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in the very early days of radio or Ah, with

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very simple radio telescopes was all you're

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doing is you're counting the amount of radio

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waves hitting your detector. So you've got

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one pixel for your entire field of view and

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then you move your field around to make an

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image. So this part of the sky is this

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bright, the one next to it is this bright and

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so on, and you raster around to build up an

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image, you move around. Nowadays I

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think that you can get multiple pixels per

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field of view. In fact, you can get many.

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That's why we can get these beautiful high

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resolution images. And, uh, it's effectively

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working, albeit at different wavelengths, in

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the same kind of general science way as an

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optical detector. In that you've got a grid

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of pixels. Each pixel is sensitive

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to light falling upon that pixel and that

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pixel is seeing a certain bit of the sky. So

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you get a measure of how bright one bit of

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the sky is, how bright the next one is, how

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bright the next one is. That then gives you

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bright and faint. So you can then make a

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monochrome image where you plot

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those brightnesses as colours, from black

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being no light to white being some light and,

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um, really bright white being the

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brightest. Right. So you can build up an

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image where each pixel is a different

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brightness. Suddenly you've got a picture.

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Andrew Dunkley: Yeah.

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Jonti Horner: What you can do then is if you're sensitive

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to different wavelengths, you can

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combine those monochromatic images to make a

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colour image just the same way as I did with

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the one behind me. So the picture I've got on

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my screen, and this is useless to those of

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you listening, but anybody live in the

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studio, I've got a picture behind me of the

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Helix Nebula, which I took with my telescope

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here. And it's a beautiful kind of true

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colour image with a little bit of hydrogen

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alpha added for those listening in. But what

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I've done here is taken images that were

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black and white, that were taken through

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filters of blue, green and

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red and combine them to make a colour image.

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So you can do that to make false colour

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images in infrared or radio, uh,

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or whatever. Sometimes what you're seeing

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is effectively a monochromatic image, but

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instead of black and white, they've used

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black and yellow to make it look nice and

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colourful. But that's effectively what's

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going on. Now, I'm not a radio astronomer.

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There's subtleties and differences in the

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technology you need to observe at, ah,

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different wavelengths compared to optical.

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And I know that's equally true of the very

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high energy stuff like gamma rays and X rays

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that need clever little Bits of technology.

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Technology to be done. But fundamentally what

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you're doing to get an image is you're

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measuring the brightness of the sky in a

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given position at the wavelength you're

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interested in and ascribing that a colour.

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And then you're building a grid of those to

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make a picture which shows you the brighter

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areas and the fainter areas. And that's

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pretty much the same no matter what you're

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looking at. It's the same technique. It's

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just using different technology because

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you're looking at different energy levels,

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different wavelengths,

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Andrew Dunkley: which is how they got the, uh,

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image of Sagittarius A and

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m. Was it M37?

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Jonti Horner: Was it the one at the middle of M81?

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Andrew Dunkley: I think M81, yeah.

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Jonti Horner: So that's the, um, big global Black hole

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telescope. I can't remember the exact name of

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it, that took advantage of the

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long wavelength because you can do very

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clever things if you can work out

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where in a particular way of your

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detectors picking things up. So you can have

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distributed detectors that are part of the

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same telescope. Now, it's really hard to

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do this with optical. So, uh, people are

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playing with interferometry and things like

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that, uh, optical wavelengths. But for

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radio waves, it's possible for you to use

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detectors scattered all around the world to

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mimic having a detector that is a radio

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telescope that is the size of the Earth.

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Andrew Dunkley: Yeah.

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Jonti Horner: Um, and that then overcomes the problem that

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the wavelengths are longer by having a

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detector that is much, much bigger to get the

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kind of resolution that you get with an

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optical telescope or even better. And it's

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using that that they were able to get these

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beautiful resolved radio images of these

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black holes. They overcame the tyranny of

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resolution being, you know,

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limited by wavelength by making a really,

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really, really big telescope, effectively.

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Andrew Dunkley: M. Yeah, it worked really well. And so those

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images are a fair representation of what

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with the naked eye, from a distance.

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Jonti Horner: I suppose if you could see radio waves.

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Andrew Dunkley: Yeah, if you could, yes.

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Jonti Horner: Things will look different at, ah, different

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wavelengths. And you see that if you do play

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with astrophotography and you look through

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different filters, it is quite striking how

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different the same object will look in

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different colours when you're just looking in

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monochrome. And that's fundamentally how we

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do a lot of the science, how we work out what

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things are made of.

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Andrew Dunkley: Yeah, thank you, Thomas, Great question.

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Lovely to hear from you. Um, notwithstanding

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the Monty Python joke,

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Generic: Roger

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Jonti Horner: in your lives right here. Also space nuts.

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Andrew Dunkley: Our, uh, next question comes from

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Dean. Uh, he's not far from

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you Hi

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Andrew Dunkley: Fred Watson and Andrew, this is Dean in

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Redcliffe in Queensland. I often hear about

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gravity waves and I get a mental picture of a

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compression wave with dispersed particles in

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space getting closer together, then further

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apart as the wave passes. But I have a

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harder time visualising what happens as the

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wave passes through a solid body such as the

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Earth, where it can be detected by the LIGO

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interferometer. I think

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that it is space that is expanding and

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contracting rather than matter. But I'm not

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sure LIGO detects the

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gravity wave because the length of the four

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kilometre tunnel changes slightly.

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What's happening at a quantum scale

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as there is space within an atom, does the

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size of the atoms change or is it just the

348
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space between the atoms? I know

349
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that the effect at quantum scale would be

350
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minute. It's interesting to think about where

351
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the limit of space stretching might be. I

352
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suspect that I'm missing something with my

353
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understanding of this. I hope you can make

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some sense of it. Thanks for the podcast.

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Andrew Dunkley: Thank you, Dean. And uh, yeah,

356
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I think he's actually referring to

357
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gravitational waves because that's what LIGO

358
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searches for. But um, yeah, I've made that

359
00:13:55.400 --> 00:13:57.520
same mistake in the past where I call them

360
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gravity waves. Um, but

361
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gravity waves, wave is a different thing.

362
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They exist too, I think.

363
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Jonti Horner: Um, yes and no. So what's strange here is

364
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that I think you hear different terminology

365
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in different disciplines. So I think a lot of

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astronomers I've heard use the term gravity

367
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waves and gravitational waves almost

368
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interchangeably because that's what they're

369
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thinking about. But it's a really good

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example of how language is contextual

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in that the words you use, you use meaning

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one thing but another person may hear them

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and hear something entirely different because

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that same word can mean a different thing to

375
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someone else. So one other place I've heard

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the term gravity wave is actually in

377
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atmospheres and um, to do with fluid

378
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movement. And so you see

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things like um, I think lens clouds, delta

380
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cumulus lenticularis and um, wave

381
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clouds are associated with something that

382
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atmospheric scientists describe as gravity

383
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waves, which are things that happen when

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you've got the interface between two fluids

385
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and you've got steady airflow over things.

386
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And if you actually do a quick Google, I just

387
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fired this up and found the Wikipedia page

388
00:15:05.100 --> 00:15:08.020
for gravity wave. There are some absolutely

389
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beautiful images of

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wind driven gravity waves in the Timor Sea.

391
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You've got some beautiful wave clouds over

392
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the us, Little bits of maths. But this ties

393
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into, I think, something I used to see when I

394
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was doing weather recordings as a teenager in

395
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Yorkshire at school, because of the shape of

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the Pennines and the kind of airflow we got,

397
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we got lens clouds relatively frequently. And

398
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I think they are linked to the phenomenon

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that atmospheric scientists would often

400
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describe as gravity waves. For clarity,

401
00:15:36.980 --> 00:15:39.420
then, I think we should call what we're

402
00:15:39.420 --> 00:15:42.420
talking about here gravitational waves. And

403
00:15:42.420 --> 00:15:45.260
I think that's probably more accurate.

404
00:15:45.260 --> 00:15:48.100
And I think possibly astronomers slipping

405
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into calling gravitational waves gravity

406
00:15:50.300 --> 00:15:52.900
waves could be the cause of confusion to

407
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people who are thinking about weather.

408
00:15:54.860 --> 00:15:57.660
Gravitational waves, Dean was

409
00:15:57.660 --> 00:16:00.660
right. Are, uh, perturbations in the

410
00:16:00.660 --> 00:16:02.940
structure of space rather than

411
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matter itself shifting. This

412
00:16:06.780 --> 00:16:08.820
makes my head hurt. I should stress that I'm

413
00:16:08.820 --> 00:16:11.140
very much not an expert here and I know I say

414
00:16:11.140 --> 00:16:13.340
that very, very often, but I'm. You know,

415
00:16:13.340 --> 00:16:16.140
it's important to note that I'm not speaking

416
00:16:16.140 --> 00:16:18.260
from a position of great authority here,

417
00:16:19.060 --> 00:16:22.020
but what you're getting are, uh, a

418
00:16:22.020 --> 00:16:24.140
phenomenon that was first predicted in the

419
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late 1800s and early 1900s. Apparently the

420
00:16:26.620 --> 00:16:29.060
predictions predated Einstein, but he kind of

421
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formalised it through general relativity

422
00:16:32.500 --> 00:16:35.320
in the form of extreme, extreme

423
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events causing perturbations to space time

424
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that ripple outwards at the speed of light,

425
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causing, effectively, waves in

426
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the spacetime continuum, effectively

427
00:16:46.720 --> 00:16:49.280
in space itself, in the same thing that is

428
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stretching with the expansion of the

429
00:16:50.800 --> 00:16:53.280
universe. Those waves,

430
00:16:53.680 --> 00:16:55.520
as they pass through, are almost

431
00:16:55.520 --> 00:16:57.400
imperceptible. They don't really interact

432
00:16:57.400 --> 00:16:59.920
much with anything. But because

433
00:17:00.080 --> 00:17:02.520
they perturb, um, space, they can have a

434
00:17:02.520 --> 00:17:04.480
measurable effect in that they can change the

435
00:17:04.480 --> 00:17:07.390
distance between two points as the wave

436
00:17:07.390 --> 00:17:09.470
passes through. Now, there's some little

437
00:17:09.470 --> 00:17:11.750
animations trying to illustrate how waves

438
00:17:11.750 --> 00:17:14.590
would look, um, on the Wikipedia

439
00:17:14.590 --> 00:17:16.310
article about gravitational waves that are

440
00:17:16.310 --> 00:17:18.030
not really helping me because they're looking

441
00:17:18.030 --> 00:17:20.190
at what would happen if you had a circle of

442
00:17:20.190 --> 00:17:21.910
points and a wave pass through. And there's

443
00:17:21.910 --> 00:17:24.550
two ways it can wibble and it can go like a

444
00:17:24.550 --> 00:17:27.350
cross, or it can go like a square, like a

445
00:17:27.350 --> 00:17:29.630
plus sign. Sorry, that doesn't particularly

446
00:17:29.630 --> 00:17:31.700
help me visualise it. But what's happening,

447
00:17:32.490 --> 00:17:34.890
to the best of my understanding, is that

448
00:17:35.290 --> 00:17:37.130
you have this tiny little

449
00:17:37.850 --> 00:17:40.810
shift in space as the wave passes through,

450
00:17:41.450 --> 00:17:44.210
which means that ligo, which has

451
00:17:44.210 --> 00:17:46.570
these two arms at right angle to each other

452
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that are like four kilometres long, has light

453
00:17:49.250 --> 00:17:52.210
bouncing along these two arms. And when

454
00:17:52.210 --> 00:17:54.090
the length of one of those arms, um, shifts

455
00:17:54.090 --> 00:17:57.090
very slightly, the light will change from

456
00:17:57.090 --> 00:17:59.210
being constructively to destructively

457
00:17:59.210 --> 00:18:01.940
interfering with each other. So a very small,

458
00:18:02.260 --> 00:18:04.420
very, very small shift in distance

459
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means that the light, when it goes along and

460
00:18:07.580 --> 00:18:09.420
bounces back, will have travelled a slightly

461
00:18:09.420 --> 00:18:11.420
different distance and Then when you

462
00:18:11.420 --> 00:18:13.100
recombine it with the light that goes down

463
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the other arm, there'll be a little bit more

464
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in phase, out of phase. So you'll see the

465
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intensity of the result changing.

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Andrew Dunkley: Gotcha.

467
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Jonti Horner: What's astonishing about this is the

468
00:18:22.740 --> 00:18:25.060
figure that um, one of these gravitational

469
00:18:25.060 --> 00:18:27.860
waves that they detect is changing the

470
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length of one of those four kilometre arms

471
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by a thousandth of the width of a proton

472
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of a subatomic particle.

473
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Andrew Dunkley: That is a quantum level.

474
00:18:37.490 --> 00:18:40.130
Jonti Horner: Yeah, it's utterly quantum level. It's

475
00:18:40.130 --> 00:18:42.330
astonishing. The analogy that's been

476
00:18:42.330 --> 00:18:44.130
published about that, to put it into scale,

477
00:18:44.130 --> 00:18:45.690
is if you think about the distance between

478
00:18:45.690 --> 00:18:48.490
the sun and Proxima Centauri, it's like

479
00:18:48.490 --> 00:18:50.130
changing that distance by the width of a

480
00:18:50.130 --> 00:18:52.530
human hair. It's

481
00:18:53.090 --> 00:18:55.530
utterly mind boggling that we can detect

482
00:18:55.530 --> 00:18:58.130
this. It's an astonishing achievement. Now,

483
00:18:58.130 --> 00:19:01.060
my understanding is limited

484
00:19:01.460 --> 00:19:03.620
and, you know, really want to stress that

485
00:19:04.100 --> 00:19:06.660
what would happen as I understand it though

486
00:19:06.660 --> 00:19:09.540
is that it isn't just a distance between the

487
00:19:09.540 --> 00:19:11.380
subatomic particles that are changing, but

488
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they themselves will change. We would change

489
00:19:13.140 --> 00:19:15.940
as that wave goes through us because space

490
00:19:16.020 --> 00:19:18.940
itself would change, would fly us, but we

491
00:19:18.940 --> 00:19:21.140
wouldn't notice it. You know, that kind of

492
00:19:21.140 --> 00:19:23.460
change is tiny compared to us. But my

493
00:19:23.460 --> 00:19:26.280
understanding, Dean, is very

494
00:19:26.280 --> 00:19:28.480
much that, uh, the particles would change and

495
00:19:28.480 --> 00:19:29.960
the distance between them would change and

496
00:19:29.960 --> 00:19:31.600
everything will be slightly compressed and

497
00:19:31.600 --> 00:19:34.280
slightly relaxed. But I stand to be

498
00:19:34.280 --> 00:19:35.960
corrected in that. Yeah,

499
00:19:36.920 --> 00:19:38.920
it's very difficult to visualise and

500
00:19:39.160 --> 00:19:40.120
challenging to understand.

501
00:19:40.920 --> 00:19:43.880
Andrew Dunkley: Yeah. Um, so the wave moves through space,

502
00:19:43.960 --> 00:19:46.400
it affects space, but the space doesn't

503
00:19:46.400 --> 00:19:48.800
actually move with the wave. It's just like a

504
00:19:48.800 --> 00:19:51.200
wave in the ocean. It doesn't like the wave.

505
00:19:51.200 --> 00:19:52.520
Isn't the water moving?

506
00:19:52.600 --> 00:19:55.040
Jonti Horner: The water still moves up and down kind of

507
00:19:55.040 --> 00:19:56.920
thing. I think the water actually goes in a

508
00:19:56.920 --> 00:19:58.700
certain way circle, doesn't it, in a wave? So

509
00:19:58.700 --> 00:20:00.460
its average position is the same, but it

510
00:20:00.460 --> 00:20:02.540
rolls back and forth and the energy is

511
00:20:02.540 --> 00:20:03.540
propagated through.

512
00:20:03.860 --> 00:20:05.700
Andrew Dunkley: Correct. That's the way I understand

513
00:20:06.660 --> 00:20:09.500
it seems logical that waves in space would be

514
00:20:09.500 --> 00:20:12.500
the same. Um, completely

515
00:20:12.500 --> 00:20:14.340
different setup, but same effect

516
00:20:15.140 --> 00:20:15.820
essentially.

517
00:20:15.820 --> 00:20:17.620
I imagine what I think will be

518
00:20:17.620 --> 00:20:19.020
Jonti Horner: interesting, and I mean this is going

519
00:20:19.020 --> 00:20:21.140
slightly off topic into philosophy, is

520
00:20:22.250 --> 00:20:24.300
uh, how these ideas will become easier to

521
00:20:24.300 --> 00:20:27.180
explain over time. So I think when

522
00:20:27.420 --> 00:20:30.220
I was at uni, people were teaching special

523
00:20:30.220 --> 00:20:32.500
and general relativity and quantum mechanics

524
00:20:32.500 --> 00:20:35.340
as m modern physics as being quite

525
00:20:35.340 --> 00:20:38.300
new. And the students were understanding them

526
00:20:38.300 --> 00:20:40.660
a bit more easily than the people who taught

527
00:20:40.660 --> 00:20:42.060
them understood them when they were students,

528
00:20:42.780 --> 00:20:45.580
because we were about 80 years

529
00:20:45.740 --> 00:20:48.100
on from these discoveries. So the people who

530
00:20:48.100 --> 00:20:50.860
were teaching us had been taught by people

531
00:20:50.860 --> 00:20:52.780
where these discoveries had been made during

532
00:20:52.780 --> 00:20:54.820
their lifetimes, potentially. Given that

533
00:20:54.820 --> 00:20:56.700
you're often taught by the old academics.

534
00:20:57.810 --> 00:21:00.210
And initially the understanding of quantum

535
00:21:00.210 --> 00:21:02.970
mechanics and relativity was way

536
00:21:02.970 --> 00:21:05.970
postdoc. And then PhD students learned it

537
00:21:05.970 --> 00:21:07.890
and then uni students learned it. And now I

538
00:21:07.890 --> 00:21:09.970
believe it's taught at high school. So as

539
00:21:09.970 --> 00:21:12.850
time goes on and people can

540
00:21:12.850 --> 00:21:14.920
explain things to the next generation, our,

541
00:21:14.920 --> 00:21:16.970
uh, kind of societal understanding of these

542
00:21:16.970 --> 00:21:19.250
concepts gets better and they get accepted.

543
00:21:19.810 --> 00:21:21.890
And you suddenly get to the point where

544
00:21:22.210 --> 00:21:23.970
primary school kids are talking about special

545
00:21:23.970 --> 00:21:25.370
relativity. I mean, they're probably not

546
00:21:25.370 --> 00:21:27.330
talking about it in the mathematical terms,

547
00:21:27.730 --> 00:21:29.790
but some of the concep are now really

548
00:21:29.790 --> 00:21:32.110
embedded in culture. And I think part of the

549
00:21:32.110 --> 00:21:35.070
problem I have with gravitational

550
00:21:35.070 --> 00:21:37.710
waves is that whilst they had been

551
00:21:37.710 --> 00:21:39.830
predicted in a kind of niche way so long ago,

552
00:21:39.830 --> 00:21:42.750
the first observations were so recent that

553
00:21:42.750 --> 00:21:44.630
I wasn't taught about gravitational waves at

554
00:21:44.630 --> 00:21:47.350
uni. They weren't part of our courses. It's

555
00:21:47.350 --> 00:21:50.350
still really cutting edge new concepts.

556
00:21:51.150 --> 00:21:53.990
And so my understanding, therefore

557
00:21:53.990 --> 00:21:56.720
my explanation, it's woolly because I've

558
00:21:56.720 --> 00:21:59.320
never had it explained by someone who has had

559
00:21:59.320 --> 00:22:01.360
it explained by someone who's had it

560
00:22:01.360 --> 00:22:03.160
explained by someone. We've not had that

561
00:22:03.160 --> 00:22:05.600
buildup of conceptual

562
00:22:05.600 --> 00:22:08.160
description, I guess, to really embed this.

563
00:22:08.160 --> 00:22:10.000
And I find it really hard to get my head

564
00:22:10.000 --> 00:22:13.000
around the first observed gravitational wave,

565
00:22:13.000 --> 00:22:15.600
I think was 2015. This is a

566
00:22:15.600 --> 00:22:18.160
decade old. So it's probably like someone

567
00:22:18.160 --> 00:22:20.880
calling into the podcast in 1925

568
00:22:20.880 --> 00:22:22.750
asking me to explain general relativity.

569
00:22:24.260 --> 00:22:27.030
Andrew Dunkley: Yes. Yeah, that's a good analogy. Um,

570
00:22:27.220 --> 00:22:29.500
Dean, thanks for the question. Hope we, we

571
00:22:29.500 --> 00:22:30.940
covered all those little gaps you were

572
00:22:30.940 --> 00:22:33.100
talking about. Boom, boom. Uh, this is Space

573
00:22:33.100 --> 00:22:35.980
Nuts with Andrew Dunkley and Professor Johnty

574
00:22:35.980 --> 00:22:37.700
Horner. A, uh, Q A edition.

575
00:22:39.780 --> 00:22:41.780
Generic: I think we need to do a little more all

576
00:22:41.780 --> 00:22:42.740
weather testing.

577
00:22:43.380 --> 00:22:45.140
Andrew Dunkley: Amen, Space Nuts.

578
00:22:45.460 --> 00:22:48.020
Our next question comes

579
00:22:48.260 --> 00:22:49.810
from David.

580
00:22:49.810 --> 00:22:52.690
Andrew Dunkley: This is David from Port Washington, New York.

581
00:22:53.410 --> 00:22:55.170
And I was thinking back to when I was a

582
00:22:55.170 --> 00:22:57.970
teenager and I heard the recording of

583
00:22:57.970 --> 00:23:00.770
the resonant frequency of the universe and I

584
00:23:00.770 --> 00:23:02.810
thought it was very cool. I'm wondering if

585
00:23:02.810 --> 00:23:05.810
there was some kind of medium that sound

586
00:23:05.810 --> 00:23:08.430
could pass through in space, like, uh,

587
00:23:08.690 --> 00:23:11.250
water, uh, or even air.

588
00:23:11.570 --> 00:23:14.250
What would I be hearing? Uh, and would it be

589
00:23:14.250 --> 00:23:17.240
beautiful or would it be terrifying? What are

590
00:23:17.240 --> 00:23:19.640
the different resonant frequencies going on

591
00:23:19.640 --> 00:23:20.840
and big explosions?

592
00:23:21.640 --> 00:23:21.650
Generic: Really?

593
00:23:21.650 --> 00:23:22.920
Andrew Dunkley: Um, interested to know.

594
00:23:23.480 --> 00:23:23.550
Generic: Bonus.

595
00:23:23.550 --> 00:23:25.720
Andrew Dunkley: Um, question. If I could breathe in space,

596
00:23:25.800 --> 00:23:27.760
what would it smell like? But I'm more

597
00:23:27.760 --> 00:23:30.200
interested to know about the sounds. Okay,

598
00:23:30.200 --> 00:23:30.920
thanks guys.

599
00:23:31.720 --> 00:23:34.080
Andrew Dunkley: Thank you. David. I love this question. It's

600
00:23:34.080 --> 00:23:36.110
a little bit different. We haven't had uh,

601
00:23:36.200 --> 00:23:38.280
one like that for a while. Although I do

602
00:23:38.280 --> 00:23:41.080
recall we did talk about

603
00:23:41.160 --> 00:23:43.920
some time back about, um, I

604
00:23:43.920 --> 00:23:46.560
can't remember exactly what the object was,

605
00:23:46.560 --> 00:23:48.380
but they were talking about what it would

606
00:23:48.380 --> 00:23:50.500
smell like if you could smell it. And

607
00:23:50.950 --> 00:23:53.900
um, you know, and that was fascinating

608
00:23:53.900 --> 00:23:55.740
in itself. But don't ask me to remember what

609
00:23:55.740 --> 00:23:58.260
it was. I think it was rotten eggs.

610
00:23:58.260 --> 00:23:58.700
Andrew Dunkley: It is.

611
00:23:58.700 --> 00:24:00.660
Jonti Horner: I think that's a concept that's often used a

612
00:24:00.660 --> 00:24:01.900
bit like we talked about in the Last

613
00:24:01.900 --> 00:24:04.500
Questions episode about the raining diamonds

614
00:24:04.500 --> 00:24:06.820
and raining, um, precious gems,

615
00:24:07.620 --> 00:24:10.540
where people try to give you a

616
00:24:10.540 --> 00:24:12.460
hook that fits in with your day to day lived

617
00:24:12.460 --> 00:24:14.260
experience to help you visualise something

618
00:24:14.260 --> 00:24:16.260
more clearly. And the

619
00:24:16.900 --> 00:24:19.500
recording of the resonant frequency of the

620
00:24:19.500 --> 00:24:22.230
univers. It's another one of those. I think

621
00:24:22.230 --> 00:24:23.710
what we're talking about there is the

622
00:24:23.710 --> 00:24:25.510
microwave background, cosmic microwave

623
00:24:25.510 --> 00:24:28.430
background, which is this very low

624
00:24:28.430 --> 00:24:31.310
frequency now radio detection, um,

625
00:24:31.670 --> 00:24:34.670
equivalent to a black body at about 2.7

626
00:24:34.670 --> 00:24:37.350
Kelvin. That is a leftover hiss from

627
00:24:37.990 --> 00:24:40.790
the Big Bang, which, when Big bang happened

628
00:24:40.790 --> 00:24:43.150
about 300,000 years later, the universe went

629
00:24:43.150 --> 00:24:45.070
from being opaque to transparent. And all the

630
00:24:45.070 --> 00:24:47.150
radiation from the heat of the universe at

631
00:24:47.150 --> 00:24:49.990
that time went out into space. Universes

632
00:24:49.990 --> 00:24:52.530
got bigger, everything's got redshifted. So

633
00:24:52.530 --> 00:24:54.410
the peak of that spectrum now looks like a

634
00:24:54.410 --> 00:24:56.760
source. That was 2.7 Kelvin. And,

635
00:24:56.760 --> 00:24:59.250
um, that microwave

636
00:24:59.250 --> 00:25:01.610
background is the source of a lot of the

637
00:25:01.610 --> 00:25:03.730
static that you used to get if you tune your

638
00:25:03.730 --> 00:25:05.970
radio between stations or if you had an old

639
00:25:05.970 --> 00:25:07.850
TV where you had to tune in on the dial or

640
00:25:07.850 --> 00:25:09.930
move the antenna around and you just got the

641
00:25:09.930 --> 00:25:12.090
noise on the screen. A significant component

642
00:25:12.090 --> 00:25:14.450
of that was a macro background. And people

643
00:25:14.450 --> 00:25:17.210
have often tried to convert that into

644
00:25:17.210 --> 00:25:20.010
a sound to give people a kind of

645
00:25:20.010 --> 00:25:21.970
emotional connection, a way of visualising

646
00:25:21.970 --> 00:25:24.930
this. Um, although that's

647
00:25:24.930 --> 00:25:27.690
turning radio waves into a sound. Well, I

648
00:25:27.690 --> 00:25:29.930
guess we do that all the time with FM and AM

649
00:25:29.930 --> 00:25:31.050
broadcast, right?

650
00:25:31.290 --> 00:25:31.690
Andrew Dunkley: Yep.

651
00:25:31.690 --> 00:25:34.290
Jonti Horner: So, uh, it kind of makes sense to people in

652
00:25:34.290 --> 00:25:36.890
terms of what the universe would sound like.

653
00:25:36.890 --> 00:25:39.730
If there was a medium in space to transmit

654
00:25:39.730 --> 00:25:42.130
the sound, it would actually depend to some

655
00:25:42.130 --> 00:25:44.170
degree of the density of that medium as well.

656
00:25:44.170 --> 00:25:46.730
So the frequency that a given sound

657
00:25:46.890 --> 00:25:49.660
will sound like changes with

658
00:25:49.900 --> 00:25:52.660
atmospheric pressure. And I've seen examples

659
00:25:52.660 --> 00:25:54.860
of this where people have put an alarm bell,

660
00:25:55.500 --> 00:25:57.980
kind of alarm clock type, ringy bell noise

661
00:25:58.380 --> 00:26:01.300
in a big bell jar and evacuated the air

662
00:26:01.300 --> 00:26:02.700
from it. And as the air pressure got lower

663
00:26:02.700 --> 00:26:04.260
and lower, I think the pitch got higher and

664
00:26:04.260 --> 00:26:07.180
higher until the sound disappeared. So you've

665
00:26:07.180 --> 00:26:09.340
got a lot of different factors that would

666
00:26:09.340 --> 00:26:12.300
come into this to do with the composition

667
00:26:12.300 --> 00:26:14.500
of the medium, the density of the medium and

668
00:26:14.500 --> 00:26:17.250
stuff like that. But let's imagine just for a

669
00:26:17.250 --> 00:26:18.650
minute, because I think this is more of a

670
00:26:18.650 --> 00:26:21.090
science fiction question than a science fact

671
00:26:21.090 --> 00:26:22.970
one in a way. And I do love it as a question

672
00:26:22.970 --> 00:26:25.450
like that. If you were floating around in the

673
00:26:25.450 --> 00:26:27.610
solar system and you were uh, beyond the

674
00:26:27.610 --> 00:26:30.050
Earth's atmosphere, what would be the main

675
00:26:30.130 --> 00:26:32.450
source of noise that you'd experience?

676
00:26:33.010 --> 00:26:35.010
To me, I would actually guess the solar wind.

677
00:26:35.330 --> 00:26:37.330
Cause you have this flow of particles coming

678
00:26:37.330 --> 00:26:39.490
past you at a speed measured in hundreds of

679
00:26:39.490 --> 00:26:42.010
kilometres a second, 100, 200, 300 kilometres

680
00:26:42.010 --> 00:26:44.890
a second. So to me, I guess the main sound

681
00:26:44.890 --> 00:26:46.890
you would hear if you were beyond the Earth's

682
00:26:46.890 --> 00:26:49.170
atmosphere and there was enough medium for

683
00:26:49.170 --> 00:26:51.290
you to listen to, would actually be the sound

684
00:26:51.290 --> 00:26:53.290
of the wind blowing, but a really intense

685
00:26:53.850 --> 00:26:56.810
gale blowing. There have been

686
00:26:56.810 --> 00:26:59.210
discussions about what you'd hear on Mars.

687
00:26:59.210 --> 00:27:01.370
Now of course, on Mars the atmospheric

688
00:27:01.370 --> 00:27:03.410
pressure is much, much lower than even at the

689
00:27:03.410 --> 00:27:06.330
altitude of Everest. So that frequency

690
00:27:06.330 --> 00:27:08.210
shifting phenomenon would come in. So

691
00:27:08.210 --> 00:27:10.090
something that you'd hear as an ice deep bass

692
00:27:10.090 --> 00:27:12.570
note on Earth, I believe, would be a higher

693
00:27:12.570 --> 00:27:14.730
pitch on Mars quite markedly.

694
00:27:14.970 --> 00:27:15.370
Andrew Dunkley: Yeah.

695
00:27:15.370 --> 00:27:18.350
Jonti Horner: Darren Squeaky Y if you're listening

696
00:27:18.350 --> 00:27:20.310
to this podcast on Mars, please wear

697
00:27:20.310 --> 00:27:22.390
headphones. Otherwise I'll sound even more

698
00:27:22.390 --> 00:27:25.300
stupid than normal, I guess. Um,

699
00:27:25.910 --> 00:27:28.670
I would imagine that in terms

700
00:27:28.670 --> 00:27:30.510
of the concept of whether it would be

701
00:27:30.510 --> 00:27:33.030
beautiful or scary, I suspect it'd be like

702
00:27:33.030 --> 00:27:35.190
white noise with a lot of different

703
00:27:35.350 --> 00:27:38.350
components coming in. If you could visualise

704
00:27:38.350 --> 00:27:39.830
different astronomical phenomena

705
00:27:39.830 --> 00:27:42.550
contributing, a lot of them are time varying,

706
00:27:42.550 --> 00:27:45.120
a lot of them are bright flashes or

707
00:27:45.120 --> 00:27:47.200
whatever. So you'll probably have an

708
00:27:47.200 --> 00:27:49.800
underlying bass noise of whatever

709
00:27:49.880 --> 00:27:52.320
with lots of other things impinging on it.

710
00:27:52.320 --> 00:27:54.760
But it's really hard to say because we're

711
00:27:54.760 --> 00:27:56.370
trying to imagine a reality that is so, ah,

712
00:27:56.400 --> 00:27:59.040
different to our own. So I'm trying to find a

713
00:27:59.040 --> 00:28:01.000
way to contextualise that, I guess.

714
00:28:01.630 --> 00:28:04.280
Um, so it'd probably be a lot more like a

715
00:28:04.280 --> 00:28:07.160
white noise machine than something clear and

716
00:28:07.240 --> 00:28:09.640
beautiful. Possibly a white noise machine on

717
00:28:09.640 --> 00:28:10.330
a very windy day.

718
00:28:11.200 --> 00:28:13.870
Andrew Dunkley: Yeah. Sounds, um, in space, um,

719
00:28:16.000 --> 00:28:18.840
it's a difficult thing to try and get your

720
00:28:18.840 --> 00:28:21.800
head around because sound needs something to

721
00:28:21.800 --> 00:28:24.440
move through and space doesn't offer a lot of

722
00:28:24.440 --> 00:28:24.720
that.

723
00:28:25.360 --> 00:28:28.240
Jonti Horner: Absolutely. And I mean to maybe give you a

724
00:28:28.240 --> 00:28:29.640
different illustration of that. If you think

725
00:28:29.640 --> 00:28:31.160
about how sounds change when you go

726
00:28:31.160 --> 00:28:33.840
underwater, how different the world

727
00:28:33.840 --> 00:28:35.640
seems if you're snorkelling or you're doing a

728
00:28:35.640 --> 00:28:36.220
scuba Dive.

729
00:28:36.690 --> 00:28:36.930
Andrew Dunkley: Yeah.

730
00:28:36.930 --> 00:28:39.170
Jonti Horner: How all the sounds are so different to you.

731
00:28:39.650 --> 00:28:42.410
Andrew Dunkley: Yeah. I'll give you an example of sound

732
00:28:42.410 --> 00:28:45.370
and witnessing its movement. Uh, and this is

733
00:28:45.370 --> 00:28:48.090
not something I'd recommend, but, uh, we were

734
00:28:48.090 --> 00:28:50.770
standing on the rim of a volcano some years

735
00:28:50.770 --> 00:28:53.490
ago, and it was active and it was going

736
00:28:54.450 --> 00:28:56.690
in our faces. Actually, we had to leave

737
00:28:56.690 --> 00:28:59.480
because it was getting in our faces. Um,

738
00:28:59.650 --> 00:29:02.450
but watching the process of the eruption,

739
00:29:02.450 --> 00:29:04.730
you see it, it before

740
00:29:05.690 --> 00:29:08.410
you hear it, but you feel it

741
00:29:09.610 --> 00:29:12.010
also before you hear it, but not until after

742
00:29:12.010 --> 00:29:12.650
you see it.

743
00:29:12.650 --> 00:29:13.130
Andrew Dunkley: Yeah.

744
00:29:13.770 --> 00:29:16.130
Andrew Dunkley: So, uh, you see the explosion, you feel the

745
00:29:16.130 --> 00:29:19.050
rumble, and then you hear it, and

746
00:29:19.050 --> 00:29:22.050
then the shockwave hits you. Yeah, it's

747
00:29:22.050 --> 00:29:24.410
a really weird combination. And look, you're

748
00:29:24.410 --> 00:29:26.970
talking about a matter of

749
00:29:27.530 --> 00:29:29.650
all of this happening over in the course of

750
00:29:29.650 --> 00:29:31.210
about a second or a second, a half,

751
00:29:32.570 --> 00:29:35.430
depending on distance. But you see it, you

752
00:29:35.430 --> 00:29:37.510
feel it, you hear it,

753
00:29:38.230 --> 00:29:40.070
you feel it in the ground, and then you feel

754
00:29:40.070 --> 00:29:40.790
the shockwave.

755
00:29:40.790 --> 00:29:41.350
Andrew Dunkley: Yeah.

756
00:29:41.830 --> 00:29:44.310
Jonti Horner: And I mean, that fits in with how

757
00:29:45.110 --> 00:29:47.070
sound travels at different speeds. So what

758
00:29:47.070 --> 00:29:49.950
you feel under your feet is effectively waves

759
00:29:49.950 --> 00:29:52.910
that you'd probably hear as sound. But going

760
00:29:52.910 --> 00:29:54.630
through a solid medium, they travel faster.

761
00:29:54.870 --> 00:29:55.310
Andrew Dunkley: Exactly.

762
00:29:55.310 --> 00:29:57.110
Jonti Horner: Shockwaves are quicker. And I mean, that

763
00:29:57.190 --> 00:29:59.750
links in part to, uh, how we know so much

764
00:29:59.750 --> 00:30:01.190
about the interior of the Earth. Because

765
00:30:01.430 --> 00:30:04.110
shock waves from earthquakes travel at

766
00:30:04.110 --> 00:30:06.110
different speeds through different media. And

767
00:30:06.110 --> 00:30:08.210
you've got T waves and S waves

768
00:30:08.450 --> 00:30:10.210
propagating around the Earth. Ah, some going

769
00:30:10.210 --> 00:30:11.850
through the Earth's, uh, interior, being

770
00:30:11.850 --> 00:30:13.810
picked up at seismographs around the world

771
00:30:14.370 --> 00:30:16.570
that very clever people can use to reverse

772
00:30:16.570 --> 00:30:18.210
engineer what the interior structure of the

773
00:30:18.210 --> 00:30:21.010
Earth's like by those differences in speed.

774
00:30:22.610 --> 00:30:25.090
Andrew Dunkley: Yeah, it was a strange experience.

775
00:30:25.250 --> 00:30:27.890
And that was the last thing I expected to

776
00:30:27.890 --> 00:30:30.530
witness. I was a bit more concerned about

777
00:30:30.610 --> 00:30:32.770
what was falling out of the sky at the time.

778
00:30:33.170 --> 00:30:35.770
I'll tell you, though, um, I took a great

779
00:30:35.770 --> 00:30:37.370
photo as we were walking off.

780
00:30:37.690 --> 00:30:39.570
Uh, when you're in tour groups, there's

781
00:30:39.570 --> 00:30:41.970
always a straggler. So we're all halfway off

782
00:30:41.970 --> 00:30:44.250
the mountain, but someone decided to stay

783
00:30:44.250 --> 00:30:47.210
behind. And that's when the biggest bang of

784
00:30:47.210 --> 00:30:50.210
the day happened. And it flung lava bombs up

785
00:30:50.210 --> 00:30:52.570
in the sky the size of soccer balls.

786
00:30:53.210 --> 00:30:55.930
And I had already put my camera in my

787
00:30:55.930 --> 00:30:57.850
pocket. I, uh, turned it off. I had enough

788
00:30:57.850 --> 00:31:00.250
time to pull the camera out, turn it on

789
00:31:01.010 --> 00:31:03.370
focus, and take a photo of this woman staring

790
00:31:03.370 --> 00:31:05.010
up at lava bombs coming down.

791
00:31:06.210 --> 00:31:09.050
It's a great photo. Um, and then it was,

792
00:31:09.050 --> 00:31:11.970
uh, only a few weeks after I got home that my

793
00:31:11.970 --> 00:31:14.610
friend, uh, sent me a video that he'd Taken

794
00:31:15.170 --> 00:31:17.650
of one of those, uh, little eruptions and

795
00:31:18.210 --> 00:31:20.610
I didn't see it, but there was a lava bomb

796
00:31:20.610 --> 00:31:23.570
landed 20 metres in front of me. I never even

797
00:31:23.570 --> 00:31:26.570
saw it. And, yeah, that kind

798
00:31:26.570 --> 00:31:27.990
of freaked me out after the fact.

799
00:31:29.580 --> 00:31:32.460
Yeah, like I said, not something I recommend,

800
00:31:32.460 --> 00:31:35.100
but, boy, what an adrenaline jolt.

801
00:31:36.060 --> 00:31:38.740
Yeah, but there's a few

802
00:31:38.740 --> 00:31:40.940
volcanoes we've visited over the years and,

803
00:31:41.240 --> 00:31:43.340
um, they've all blown up since we've been to

804
00:31:43.340 --> 00:31:45.700
them. So the one at Vanuatu stopped air

805
00:31:45.700 --> 00:31:48.700
traffic. Uh, we were at Matt Etna,

806
00:31:49.140 --> 00:31:50.980
uh, a couple of years ago. Well, look what

807
00:31:50.980 --> 00:31:53.520
it's doing at the moment. Kilauea. It's gone

808
00:31:53.670 --> 00:31:55.670
off, like, several times since we were there.

809
00:31:55.990 --> 00:31:58.190
In fact, the observation deck in the

810
00:31:58.190 --> 00:32:00.790
caldera, uh, where we

811
00:32:01.190 --> 00:32:03.590
looked at Kilauea, was

812
00:32:03.590 --> 00:32:06.430
obliterated about a month after we were

813
00:32:06.430 --> 00:32:06.710
there.

814
00:32:08.230 --> 00:32:10.510
Jonti Horner: So when are you taking a holiday to Naples or

815
00:32:10.510 --> 00:32:11.590
to Yelliston?

816
00:32:11.830 --> 00:32:14.230
Andrew Dunkley: Well, actually, we've been to Naples, so,

817
00:32:14.710 --> 00:32:17.530
um, it wasn't, um,

818
00:32:17.530 --> 00:32:19.950
Vesuvius, though, that went off when we were

819
00:32:19.950 --> 00:32:21.710
there. It was, um, Stromboli.

820
00:32:21.710 --> 00:32:23.710
Jonti Horner: Yeah, well, they're quite worried about Campo

821
00:32:23.710 --> 00:32:26.050
Fiegri, I think it's called, which is Big

822
00:32:26.210 --> 00:32:29.210
Field under Naples. That, yes, will

823
00:32:29.210 --> 00:32:30.610
be a disaster when it goes.

824
00:32:31.010 --> 00:32:33.770
Andrew Dunkley: Well, like, if you go out

825
00:32:33.770 --> 00:32:36.370
into the. Into the bay and, and

826
00:32:36.530 --> 00:32:39.370
do a bit of, um, skin diving down to the. To

827
00:32:39.370 --> 00:32:41.689
the bottom, there's all this gas coming up

828
00:32:41.689 --> 00:32:42.770
through the sand, like.

829
00:32:43.170 --> 00:32:45.730
Jonti Horner: And I keep seeing reports of the amount of

830
00:32:45.730 --> 00:32:47.290
swelling of the lava dome and things like

831
00:32:47.290 --> 00:32:49.130
this. I mean, yeah, I personally would not

832
00:32:49.130 --> 00:32:51.570
feel all that comfortable living in that area

833
00:32:51.570 --> 00:32:52.660
or even necessarily visiting,

834
00:32:55.130 --> 00:32:57.370
but hopefully, you know, it will not be a

835
00:32:57.370 --> 00:32:59.810
problem within our lifetimes and the science

836
00:32:59.810 --> 00:33:01.570
will continue to improve to the level that

837
00:33:01.570 --> 00:33:03.170
they get enough warning to get everybody out

838
00:33:03.170 --> 00:33:03.930
when it goes.

839
00:33:04.330 --> 00:33:06.650
Andrew Dunkley: Yeah, that's the problem, isn't it? Uh, and

840
00:33:06.650 --> 00:33:09.610
even in, uh, New Zealand they've got, um, the

841
00:33:10.010 --> 00:33:12.690
dormant, uh, volcano in the

842
00:33:12.690 --> 00:33:15.050
harbour at Auckland. And

843
00:33:16.170 --> 00:33:18.730
I was talking to a journalist friend of mine

844
00:33:18.810 --> 00:33:21.370
who lived in New Zealand, uh, some years ago

845
00:33:21.370 --> 00:33:23.530
when I worked for the abc, and he was saying,

846
00:33:23.850 --> 00:33:26.390
look, it is a worry there too, if this thing

847
00:33:26.390 --> 00:33:28.750
ever wakes up. There are only two roads out

848
00:33:28.750 --> 00:33:31.270
of Wellington, uh, out of Auckland,

849
00:33:31.990 --> 00:33:34.350
and you've got a million people there or

850
00:33:34.350 --> 00:33:37.150
something. And how are they going to get

851
00:33:37.150 --> 00:33:37.430
out?

852
00:33:37.430 --> 00:33:39.310
Jonti Horner: It was actually fascinating. I was in New

853
00:33:39.310 --> 00:33:41.030
Zealand a couple of times earlier in the year

854
00:33:41.190 --> 00:33:43.430
and went through Auckland and spotted all

855
00:33:43.430 --> 00:33:44.710
these little humps and thought, that's

856
00:33:44.710 --> 00:33:46.710
interesting. Looked into it. I just pulled up

857
00:33:46.710 --> 00:33:49.710
the information here. The metropolitan area

858
00:33:49.710 --> 00:33:51.960
of Auckland contains 53

859
00:33:51.960 --> 00:33:54.680
volcanoes because it's a little volcanic

860
00:33:54.680 --> 00:33:56.920
field of these small little

861
00:33:57.320 --> 00:33:59.640
maas and tuff rings and all this stuff.

862
00:34:01.160 --> 00:34:03.520
Um, none of them are thought to have erupted

863
00:34:03.520 --> 00:34:05.800
more than once, except for one of them called

864
00:34:06.040 --> 00:34:09.040
Orangitoto. But it is

865
00:34:09.040 --> 00:34:10.960
an active volcanic area. Apparently the first

866
00:34:10.960 --> 00:34:13.920
vent in that area erupted 193,000

867
00:34:13.920 --> 00:34:15.760
years ago. And the most recent one was about

868
00:34:15.760 --> 00:34:16.730
600 years ago.

869
00:34:16.879 --> 00:34:17.119
Generic: Go.

870
00:34:17.359 --> 00:34:17.839
Andrew Dunkley: Yeah.

871
00:34:18.000 --> 00:34:19.599
Jonti Horner: Um, and that's from the one in the water,

872
00:34:20.460 --> 00:34:23.399
um, just east of the city. But,

873
00:34:23.399 --> 00:34:25.439
yeah, must be a fascinating place to live.

874
00:34:25.999 --> 00:34:28.879
But that plus the earthquakes,

875
00:34:29.039 --> 00:34:31.919
plus the psalms that get there. It's

876
00:34:31.919 --> 00:34:33.959
good to live in interesting times. But that

877
00:34:33.959 --> 00:34:35.359
might be a little bit too full on.

878
00:34:35.759 --> 00:34:38.239
Andrew Dunkley: Yeah. Well, we visited Christchurch,

879
00:34:38.310 --> 00:34:41.159
uh, coming up on four

880
00:34:41.159 --> 00:34:43.959
years ago now, and, uh, it had had that

881
00:34:43.959 --> 00:34:46.230
massive earthquake, that tragic earthquake.

882
00:34:46.230 --> 00:34:49.190
And, uh, even then you could. That

883
00:34:49.190 --> 00:34:51.590
they hadn't come close to rebuilding.

884
00:34:52.230 --> 00:34:55.030
And they even have, um, a

885
00:34:55.030 --> 00:34:57.750
museum, Quake City, I think it's called In

886
00:34:58.070 --> 00:35:00.310
Christchurch, which I highly recommend. It's

887
00:35:00.470 --> 00:35:01.670
fascinating. Yeah.

888
00:35:02.270 --> 00:35:04.030
Uh, we got off the topic, uh, did we talk

889
00:35:04.030 --> 00:35:06.030
about smells in space? If you could take a

890
00:35:06.030 --> 00:35:08.950
big inhale, what would it be like?

891
00:35:08.950 --> 00:35:09.550
Andrew Dunkley: I'm not sure.

892
00:35:09.550 --> 00:35:11.350
Jonti Horner: I mean, this is one of those things that

893
00:35:11.350 --> 00:35:14.260
people use to give you a handle

894
00:35:14.420 --> 00:35:17.220
to get on. So when we discover interesting

895
00:35:17.220 --> 00:35:19.540
things in the atmosphere of different places,

896
00:35:20.820 --> 00:35:23.140
usually, um, the things that relate to

897
00:35:23.460 --> 00:35:25.500
gases that we'd have on Earth are used to

898
00:35:25.500 --> 00:35:27.300
say, oh, this place would smell of whatever.

899
00:35:27.700 --> 00:35:29.980
Most common of them is hydrogen sulphide,

900
00:35:29.980 --> 00:35:32.780
which is your rotten egg smell, which is why

901
00:35:32.780 --> 00:35:34.940
people talk so much about exoplanets that

902
00:35:34.940 --> 00:35:37.420
smell like rotten eggs. But I think there was

903
00:35:37.420 --> 00:35:40.060
one recently that wasn't there. Something

904
00:35:40.060 --> 00:35:41.660
saying it was a giant gas cloud that would

905
00:35:41.660 --> 00:35:44.310
have smelled or tasted of strawberries. Big

906
00:35:44.310 --> 00:35:47.030
Said found a long chain hydrocarbon that was

907
00:35:47.030 --> 00:35:49.750
part of the test sensation. That is a nice,

908
00:35:49.830 --> 00:35:52.510
nice strawberry. So I think most of space

909
00:35:52.510 --> 00:35:55.150
would not smell particularly pleasant, but

910
00:35:55.150 --> 00:35:57.470
you wouldn't smell very much. But there's

911
00:35:57.470 --> 00:35:58.990
dust and debris around. But there's also a

912
00:35:58.990 --> 00:36:00.910
lot of gases that you really wouldn't want to

913
00:36:00.910 --> 00:36:02.950
inhale. I mean, I'm thinking of hydrogen

914
00:36:02.950 --> 00:36:05.530
cyanide and things like this. So, uh,

915
00:36:05.550 --> 00:36:06.950
inhale at your own risk.

916
00:36:07.270 --> 00:36:09.350
Andrew Dunkley: Well, I think you'd only inhale once in space

917
00:36:09.350 --> 00:36:10.470
and that'd be the end of that.

918
00:36:10.470 --> 00:36:11.500
Jonti Horner: Oh, absolutely, absolutely.

919
00:36:11.660 --> 00:36:13.230
Generic: Probably. All right.

920
00:36:13.230 --> 00:36:14.900
Andrew Dunkley: Uh, David, thanks for that. Great question.

921
00:36:14.900 --> 00:36:16.860
That was a lot of fun to discuss and brought

922
00:36:16.860 --> 00:36:18.700
up a lot of things in my mind about some of

923
00:36:18.700 --> 00:36:21.340
the experiences with sounds and smells I've

924
00:36:21.340 --> 00:36:22.060
had in my life.

925
00:36:22.650 --> 00:36:24.820
Uh, and that brings us to the end of a Q and

926
00:36:24.820 --> 00:36:26.500
A edition. If you would like to send us some

927
00:36:26.500 --> 00:36:28.620
questions, please do through our website

928
00:36:28.620 --> 00:36:31.260
spacenutspodcast.com spacenuts

929
00:36:31.340 --> 00:36:33.740
IO or do a search for SpaceNuts

930
00:36:33.740 --> 00:36:36.220
podcast in your favourite search engine. If

931
00:36:36.220 --> 00:36:37.980
you just do a search for Space Nuts, it'll

932
00:36:37.980 --> 00:36:39.420
take you to that horrible movie.

933
00:36:40.970 --> 00:36:42.950
Um, well, it's probably not that horrible,

934
00:36:43.110 --> 00:36:45.390
but anyway, uh, that's how you do it. Just

935
00:36:45.390 --> 00:36:47.910
click on the AMA tab and send us text or

936
00:36:47.910 --> 00:36:49.630
audio questions. And don't forget to tell us

937
00:36:49.630 --> 00:36:51.350
who you are and where you're from. And have a

938
00:36:51.350 --> 00:36:52.630
look around on our website while you're

939
00:36:52.630 --> 00:36:54.750
there. Jonty, thanks very much. Good to see

940
00:36:54.750 --> 00:36:55.110
you again.

941
00:36:55.110 --> 00:36:56.590
Jonti Horner: That's absolute pleasure. It's good to catch

942
00:36:56.590 --> 00:36:58.510
up and, you know, I'll catch you again the

943
00:36:58.510 --> 00:36:59.910
next time Fred Watson's on a jolt.

944
00:36:59.910 --> 00:37:01.470
Andrew Dunkley: Yeah, I think you'll be back after this

945
00:37:01.470 --> 00:37:03.550
episode, but we'll, um, we'll keep you on

946
00:37:03.550 --> 00:37:05.990
standby, but we'll talk again down the track.

947
00:37:06.150 --> 00:37:06.710
Jonti Horner: Absolutely.

948
00:37:06.710 --> 00:37:09.350
Andrew Dunkley: Look forward to it, Professor Jonty Horner,

949
00:37:09.350 --> 00:37:10.910
professor of Astrophysics at the University

950
00:37:10.990 --> 00:37:12.910
of Southern Queensland. And thanks to Huw in

951
00:37:12.910 --> 00:37:15.070
the studio, uh, who did actually turn up

952
00:37:15.070 --> 00:37:16.590
today, but they wouldn't let him in because

953
00:37:16.590 --> 00:37:19.230
he smells. And from me, Andrew Dunkley.

954
00:37:19.230 --> 00:37:20.910
Thanks for your company. We'll see you on the

955
00:37:20.910 --> 00:37:23.150
next episode of Space Nuts. Bye. Bye.

956
00:37:24.350 --> 00:37:26.630
You've been listening to the Space Nuts

957
00:37:26.630 --> 00:37:29.590
Jonti Horner: podcast, available at

958
00:37:29.590 --> 00:37:31.630
Apple Podcasts, Spotify,

959
00:37:31.790 --> 00:37:34.480
iHeartRadio or your favourite podcast

960
00:37:34.480 --> 00:37:36.200
player. You can also stream on

961
00:37:36.200 --> 00:37:37.880
demand@bytes.com.

962
00:37:38.200 --> 00:37:40.280
Andrew Dunkley: this has been another quality podcast

963
00:37:40.280 --> 00:37:42.440
production from bytes.um com.