Snowball Earth Theories, High-Energy Neutrinos & The Fascinating MWC349A

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Andrew Dunkley: Hi there. Thanks for joining us on a Q and A

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edition of Space Nuts. My name is Andrew

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Dunkley and this is the. The show we do each

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week where you supply the agenda

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and we pretend we know what we're talking

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about. And questions are coming in,

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uh, for this week's show from Peter, who's

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asking about climate change.

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Jonti Horner: Paul is.

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Andrew Dunkley: Well, I suppose it's a similar story.

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Snowball, uh, Earth and, uh, a couple of

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objects of interest. Uh, Casey is asking

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about KM

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M3230213A.

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Know all about it. And an even more obscure

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thing. Henrik has asked about

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MWC3498, which I just did a

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Google search for and it came up blank.

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Anyway, it's an A at the end, not an A. I had

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fun with that. Ah, is that the one? All

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right. And that's what we're talking about

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with that little voice you just heard in the

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background on this edition of space

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nuts.

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Voice Over Guy: 15 seconds. Guidance is internal.

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10, 9. Ignition

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sequence start. Space nuts. 5, 4, 3,

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

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3, 2, 1. Space nuts. Astronauts

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report it feels good.

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Andrew Dunkley: And that voice belongs to none other than

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Professor Jonti T. Horner, professor of

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Astrophysics at the University of Southern

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Queensland, Jonti. Hello again.

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Jonti Horner: Good afternoon. Yeah, clearly professor of

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interruptions. This is what happens when I've

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had enough time for the coffee to kick in.

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Andrew Dunkley: Uh, yes, it's been, um, what, four

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days and we're still wearing the same

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clothes.

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Jonti Horner: Absolutely.

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Andrew Dunkley: Yeah, I get a lot of mileage out of that

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joke. Yeah.

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Jonti Horner: Um, but you've been done.

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Had a musical interlude. Haven't I have.

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Andrew Dunkley: Look, I, um.

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Jonti Horner: It.

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Andrew Dunkley: It was just. Last weekend was a long weekend,

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uh, in New South Wales, and I think it was in

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Queensland too. But, um, it was the weekend

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that Taylor Swift released her latest

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album. And, uh,

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I've got three granddaughters, all of

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Taylor's swifty age. And

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uh, we. Yeah, we took them to see

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the launch of her new album. Uh, and,

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uh, I. Look, I've got to tell you, I really

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did, I did. I enjoy it.

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Yes. It's not aimed at

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me or my demographic, but, um,

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it was, uh, it was interesting to

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watch some of the thinking behind the artist

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and some of the creativity that went into

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film clips and things like that. That's the,

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that's what I got out of it. But what, uh, an

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extraordinary.

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Jonti Horner: It's one of the things I love.

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I know we've gone totally off topic straight

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away, but my favorite critic, and the kind of

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only one I pay attention to, really is a guy

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called Mark commodity in the UK who's, um,

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they used to be on BBC Radio 5 live and now

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they've got their own independent, um, thing.

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And it's one of those things that's like

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comfort food for the soul that you can listen

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to and just makes your children relax. But

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part of what's nice about him is that you get

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a lot of film critics who, if a film's not

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made for them, are in some misdiabos about

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it. Right. And you know, I remember this with

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the Twilight films, which I'm not the target

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audience, they're not my cup of tea, but they

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got panned because they're made for

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teenage girls and film critics are elderly

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men and there's a slightly different

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demographic there. And this guy's brilliant

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because he'll m. Make the point. You know,

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I'm not the target audience for this. I'm

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very clearly not it and I enjoyed it. Okay.

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But you look around the room at the people

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who are the target audience and they love it.

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So it's obviously doing well. I think it's

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the same with what you're saying by the

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Taylor Swift stuff. We're not the target

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audience. But you can appreciate that this is

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someone who's awesomely talented and ah, for

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the target audience, it's really

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fundamentally awesome, you know.

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Andrew Dunkley: Yeah. Uh, I was still working on

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radio, uh, when she was, uh,

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announced by Time magazine as Person of the

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Year. And I did a big, big

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statement at the time as far as I was

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concerned, uh, about why she deserved

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it because she brought light into the world

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at a very dark time towards the end of COVID

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And um, but then they went

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and made Donaldjohanson Trump the, uh, Person

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of the Year. So anyway, whatever.

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Jonti Horner: Um, can't see the light without having

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darkness. Right.

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Andrew Dunkley: And I will say one of the songs on the new

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album has got to be about Donaldjohanson

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Trump. So anyway, he's after

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a Nobel priest Peace Prize and the word on

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the hill is that, uh, you might just get

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it. Uh, we won't go there. It's not

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our agenda. But, uh, we will go to some

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questions. Why don't we try and tackle this

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very first one? And this one

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comes from Peter.

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With all this climate change happening, I,

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uh, was wondering how CO2 is

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warming the planet when it's heavy. Heavier

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than air. Maybe the problem is the axis of

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the planet has moved because of all the

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millions of tons of minerals that have been

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moved. Maybe someone should check the

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axis angle. Geez, Peter, I

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think I've heard this theory Once before.

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I doubt that the amount of stuff we take out

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of the ground and move around the planet is

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going to make that big a difference

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to the tilt.

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Jonti Horner: No, and the beauty is we can measure the

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tilt. I mean, I grew up in the north

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of England, and high in the sky was

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Polaris, the pole star, which is the

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direction that the northern end of the

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Earth's, uh, spin axis points to. I'm very,

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very close to that star. So we can see

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exactly where the spin axis of the Earth is

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pointing. We can measure its spin rate. And

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it is right that moving material around

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on the Earth will to some degree change its

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spin and change its spin axis tilt.

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Um, but, and it's a very big but the amount

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of change that you get from human activity is

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very, very, very, very small. A much

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bigger shift in mass, for example, happens

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with melting of the polar caps. Yeah, if you

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melt the polar caps, you move the water. The

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water settles all around the Earth, so you're

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effectively moving mass from near the poles

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to near the equator. And that changes the

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Earth's rotational angular momentum and will

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change the Earth's spin very, very, very,

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very slightly. But we're now incredibly

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technologically capable, so we can measure

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things that are that small. And a good

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example of that was the big Indian Ocean

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tsunami. The earthquake that caused that, uh,

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on the Pacific Rim had a measurable effect on

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the Earth's spin. But if I remember rightly,

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and I stand to be corrected here, that

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measurable effect was something like one, one

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millionth of a second in the spin rate or

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something like that. And we can measure that,

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but it's not like you'd notice it in your day

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to day life. And it's not like that would be

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big enough to cause the impact on the climate

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that we see today. Now, I understand

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that, thanks to, uh, decades of

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discussion, that climate change is still a

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bit of a controversial topic with some

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people. And I'm quite

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fundamentally comfortable saying climate

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change is a real thing, that the climate is

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changing. I spent three years early in my

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career living in Switzerland, and when I was

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in Switzerland, I used to go skiing, because

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skiing's awesome. And if you're in

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Switzerland, why wouldn't you? And all these

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beautiful little towns that I went to in the

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winter, and then you went back in the summer

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and you went walking in the hills instead of

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skiing because all the snow had gone. They

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all have these photos from 50 or 100 years

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ago where you have the village in the

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foreground and the glacier in the background

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winding out of the hills. And then if you're

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up there in the summer, you go out and look,

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and it isn't there anymore. It's retreated

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that far. And I think that's fundamentally

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why in a lot of those countries with Alpine

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regions, climate change has been accepted for

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much, much longer, because you can really

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physically see the effects. And so it's very

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clear that it's happening. And the argument

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that it's caused by humor rather than

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something natural, the strongest evidence for

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that, to be honest, is the speed at which

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it's happening is unprecedented. The natural

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effects that could cause it, like the

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transition from the ice ages to the

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interglacials, and we'll talk about this a

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bit more later on, are, uh, much more

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gradual. Changes in brightness of the sun are

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much more gradual. And in fact, the sun has

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dimmed a little bit over the time that we've

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been measuring climate change due to little

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bits of tweaks in its behavior. So if

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the climate wasn't changing, we'd actually be

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slightly cooler now than we were a couple of

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hundred years ago, only very slightly. But

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that leads to this perverse and confusing

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statistic that 110% of all climate change is

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caused by humans because we're not just

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making it warmer, but we're offsetting the

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cooling as well. Yeah, so that's all the

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background to it here, how carbon dioxide

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plays a role. Even though it's, you know,

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heavier than air, it's still gas, it still

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floats around up there. It's not like it all

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sits at ankle level on the Earth. But even if

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it did, it would still be fairly effective

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because what carbon dioxide is in a really

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broad sense is it's like a good winter doona

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that you've got. The way that

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I can understand this as an astronomer most

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obviously is, uh, I think back m to again.

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When I was a kid, 1983, when I was five years

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old, there was this satellite launch called

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the infrared astronomical satellite IRAs.

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And that was really foundational for a lot of

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what we've learned about planets around other

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stars, because it was a tool that first

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allowed us to find debris disks around stars,

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which are, uh, the leftovers from planet

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formation. And that was a bit of a shock

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because stars didn't look how they were

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expected to. Three of them in particular.

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Vega, Fomalkauten, Beta Pictoris. They were

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brighter in the infrared wavelengths than we

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expected. They thought the satellite was

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broken. Then they realized that, no, really,

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the stars just had all this debris around

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them that was getting hot, warming up, and

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Giving off radiation and infrared

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wavelengths. So this tells us that

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when you heat something up, it radiates that

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energy away in infrared. And that's why

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thermal imaging cameras work. You can see

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people at night if you're using a thermal

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imaging camera because they're warmer than

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the surrounding area, so they give off more

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infrared radiation. You can see that. But the

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reason we had to launch IRAs was that you

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can't do infrared astronomy from the ground

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except a couple of very specific wavelengths.

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And uh, the reason that you can't do infrared

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astronomy from the ground is that the

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atmosphere is fundamentally opaque at

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infrared wavelengths. And a big part of that

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is carbon dioxide. So if you've got a photon

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of infrared radiation, it coming into our

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atmosphere, we'll essentially see our

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atmosphere as utterly thick cloud. It will be

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absorbed and re emitted back out.

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Optical light, visible light makes it through

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the atmosphere intact. And that's why if I

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look out of the window at the minute, we've

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got a lovely sunny day and I can see what I'm

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doing. And, um, that solar radiation comes in

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and it warms the Earth up. And what does the

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Earth do? It radiates that energy back

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outward at infrared wavelengths. But because

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the atmosphere is opaque at infrared

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wavelengths, that energy gets absorbed and re

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emitted. And it'll be re emitted randomly in

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any given direction. So the odds are it'll

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come back down. So in other words, that

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radiation gets trapped. And that's how the

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doona works. That's how the carbon dioxide's

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working. Now the carbon dioxide

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we've got in our atmosphere is really

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effective as a greenhouse gas. It's actually

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mostly saturated. So adding

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some carbon dioxide from no carbon dioxide

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would have a much bigger effect than adding

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carbon dioxide to the atmosphere. Now, when

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we've got a fair bit of it in there already,

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but it's not totally saturated. So what that

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means is as we add more carbon dioxide, it

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can still have a bigger effect. And, um,

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that's why as we put more carbon dioxide into

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the atmosphere, the Earth gets warmer because

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the Dooner gets more effective.

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There are other gases that are effective

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greenhouse gases as well. Methane is a really

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good example. Methane is actually much more

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effective than carbon dioxide. But the

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difference is methane's fairly short lived in

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the atmosphere. Methane molecules on average

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will be removed from the atmosphere within

305
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400 years by interacting with oxygen.

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Carbon dioxide is only removed by life

307
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or by weathering. You know, if you get lots

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of rain on the continents, that breaks up the

309
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rocks, the rocks crumble down. Chemistry

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happens. Carbon dioxide can be pulled out

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into the rocks and locked up in the surface.

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They're the mechanisms that get rid of carbon

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dioxide and they're slower. So that's part of

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why carbon dioxide is a problem, because when

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we put it in the atmosphere, it's going to

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hang around for a good long time. But that

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hopefully kind of answers that question, that

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I am respectful of the fact that it's hard

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for people to comprehend how we

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can change the world's environment. Because

321
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you think of yourself and your friends and

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you think the Earth's so big and we're so

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small, how can we have that much of an

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effect? And it's hard to come to terms with

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just how many people there are and just how

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much stuff we're doing and pumping stuff into

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the atmosphere. Yeah, it's a bit

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misleading to say, you know, if you change to

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an EV rather than a petrol car, you'll save

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the world, but it'll contribute a little drop

331
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in the ocean towards lessening climate

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change potentially in the long term. And, um,

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that's kind of what people are looking at.

334
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But fundamentally, this is what's happening.

335
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It's very, very well established. Nothing

336
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astronomically can even come close to

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explaining what we're seeing. So when you

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rule out all the other options, the only

339
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thing that's left is human influence. And

340
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that's kind of sad, but shows what an

341
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effective species we are at changing our

342
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environment, you know?

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Andrew Dunkley: Well, hopefully we can be just as effective

344
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in finding a solution, but I think, uh,

345
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to do that, everybody has to be on the same

346
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page, and that's just not the case at the

347
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moment.

348
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Jonti Horner: I'm an optimist. I mean, there's.

349
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There's real challenges here. I remember

350
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there was an incredible article by a guy

351
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called Jeff Masters who used to run the

352
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Weather Underground site, used to write blogs

353
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there. Uh, yeah. Um, and he wrote about. I

354
00:13:10.380 --> 00:13:11.780
think it was book review, actually. But he

355
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wrote about something called Manufactured

356
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Doubt, which is a whole industry that has

357
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sprung up to sow confusion

358
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over something that should be settled science

359
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in order to allow business to operate without

360
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being restricted effectively. And, um, it

361
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first came about with smoking. So cigarette

362
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smoking. Tobacco smoking was known to be very

363
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harmful to people going back 100 years from

364
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now. But even when I was growing up in the

365
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1980s, he still had smoking in public places.

366
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You still had it everywhere. You still have

367
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adverts on TV and tobacco sponsorship.

368
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Because there'd been this very cleverly

369
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managed marketing strategy of casting doubt

370
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on the science and casting doubt on the

371
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scientists involved, effectively slandering

372
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them. And you have things like, you know, top

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sportsmen in the world, footballers and

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cricketers and things like this being

375
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sponsored by tobacco companies and smoking

376
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cigarettes and interviews and giving this

377
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impression. Can't be harmful, can it? I mean,

378
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look, here's one of the fittest athletes in

379
00:14:05.190 --> 00:14:06.830
the world and they smoke and that makes them

380
00:14:06.830 --> 00:14:08.470
a great athlete. You shouldn't see children.

381
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And what was interesting in this article from

382
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Jeff Masters, who's a very powerful advocate

383
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for knowledge, uh, about climate change, was

384
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that, uh, there is a lot of evidence that the

385
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companies that used to do that for tobacco

386
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through the 1980s were brought on board by

387
00:14:24.310 --> 00:14:27.070
the big oil companies to do the same kind of

388
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strategy. And it's been incredibly effective.

389
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And I think it's led to this wider thing of

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diminishing trust in science and greater

391
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doubt in it, which has led to the challenges

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we face now with things like vaccines, with,

393
00:14:40.640 --> 00:14:43.600
you know, flat earthing to some degree, with

394
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places where people are skeptical and

395
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don't trust scientists and don't trust

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science, even though science is so

397
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fundamental and foundational for our day to

398
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day lives. And it's really sad. But the flip

399
00:14:54.200 --> 00:14:56.880
side is we got cigarettes banned,

400
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people's health has improved. We, you know,

401
00:14:59.440 --> 00:15:01.360
no longer do you go to a pub and the walls

402
00:15:01.360 --> 00:15:03.200
are grimy and the windows are dark because of

403
00:15:03.200 --> 00:15:04.720
all the cigarette smoke. No longer do you get

404
00:15:04.720 --> 00:15:07.060
on a train and have to cough your way to your

405
00:15:07.060 --> 00:15:09.620
destination. Things have changed and I think

406
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we're starting to see the same change with

407
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climate change and, um, with the actions that

408
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we can take. And it's not happening out of

409
00:15:15.340 --> 00:15:16.620
the goodness of people's hearts. It's

410
00:15:16.620 --> 00:15:18.740
happening because commercially it's now

411
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becoming viable to make the changes. Yes,

412
00:15:21.420 --> 00:15:23.500
electric vehicles are a really good example.

413
00:15:24.220 --> 00:15:26.220
Back in the early 1900s you had electric

414
00:15:26.220 --> 00:15:28.140
vehicles, we had electric milk floats in the

415
00:15:28.140 --> 00:15:29.820
uk, but they were an oddity and there were

416
00:15:29.820 --> 00:15:32.180
specific use. But it's finally got to the

417
00:15:32.180 --> 00:15:33.780
point where those kind of vehicles can be

418
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competitive with combustion engine vehicles,

419
00:15:37.000 --> 00:15:38.800
can even possibly work out cheaper and more

420
00:15:38.800 --> 00:15:40.320
efficient and suddenly there's an incentive

421
00:15:40.320 --> 00:15:42.360
for people to get them, not because they're

422
00:15:42.360 --> 00:15:43.960
doing good for the planet, but because it's a

423
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better option for them. And that's the kind

424
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of change that hopefully is going to improve

425
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things.

426
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Andrew Dunkley: Yes, yes, I hope you're right. I

427
00:15:50.760 --> 00:15:53.200
suppose the other difficulty that comes into

428
00:15:53.200 --> 00:15:56.080
play with trying to change the minds of

429
00:15:56.080 --> 00:15:59.000
people and get the right thinking happening

430
00:15:59.480 --> 00:16:02.000
is social media, because there's so much

431
00:16:02.000 --> 00:16:04.920
scandal going through social media and as

432
00:16:04.920 --> 00:16:07.400
I mentioned, in the last program, um,

433
00:16:08.760 --> 00:16:11.480
we now have artificial intelligence, so

434
00:16:11.480 --> 00:16:13.640
you don't even know what you're looking at is

435
00:16:13.640 --> 00:16:14.480
real anymore.

436
00:16:14.480 --> 00:16:14.920
Speaker C: It's.

437
00:16:15.160 --> 00:16:18.160
Jonti Horner: Yeah, it's all saying that. And

438
00:16:18.160 --> 00:16:20.080
I know it from a Terry Pratchett. But like

439
00:16:20.080 --> 00:16:21.960
many things, Terry Pratchett, he was probably

440
00:16:22.440 --> 00:16:24.520
referencing people before. But this whole

441
00:16:24.520 --> 00:16:26.080
idea that a lie can run around the world

442
00:16:26.080 --> 00:16:28.440
before the truth can get its boots on, it's

443
00:16:28.440 --> 00:16:30.520
very easy to tell a convenient lie. And

444
00:16:30.520 --> 00:16:33.340
people are naturally biased as

445
00:16:33.340 --> 00:16:35.140
humans, with all the different cognitive

446
00:16:35.140 --> 00:16:37.340
biases we've got, there's a confirmation bias

447
00:16:37.340 --> 00:16:39.020
that you remember the things that fit in well

448
00:16:39.020 --> 00:16:41.260
with your lived experience and not the things

449
00:16:41.260 --> 00:16:43.580
that disagree with it. And, um, my lived

450
00:16:43.580 --> 00:16:45.220
experience is that I don't change the world

451
00:16:45.220 --> 00:16:47.060
when I go around. I'm not fundamentally

452
00:16:47.060 --> 00:16:48.700
altering the world around me, which I live

453
00:16:48.700 --> 00:16:50.780
in. So it's very easy when somebody says,

454
00:16:50.780 --> 00:16:53.620
we're not changing the world. Climate change

455
00:16:53.620 --> 00:16:55.380
can't be real, because how could you change

456
00:16:55.380 --> 00:16:57.380
the world for people to really empathize with

457
00:16:57.380 --> 00:16:59.700
that and fit in with it in just the same way

458
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that people who are getting vaccinated,

459
00:17:02.100 --> 00:17:04.100
they'll remember that their anti ulcer had a

460
00:17:04.100 --> 00:17:06.620
bad reaction to the vaccine, but they don't

461
00:17:06.620 --> 00:17:09.500
remember that many people who have had the

462
00:17:09.500 --> 00:17:11.220
vaccine and not had a reaction, but didn't

463
00:17:11.220 --> 00:17:12.860
die from the thing they were vaccinated

464
00:17:12.860 --> 00:17:15.100
against because they were vaccinated. So you

465
00:17:15.100 --> 00:17:17.060
get that confirmation bias that feels like it

466
00:17:17.060 --> 00:17:19.700
supports the idea that vaccines are bad

467
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when in fact they're not. And fundamentally,

468
00:17:22.380 --> 00:17:24.340
this is why as scientists, we use statistics

469
00:17:24.340 --> 00:17:26.880
for all these things. Lies down, blind

470
00:17:26.880 --> 00:17:29.560
statistics. We use statistics to try and

471
00:17:29.560 --> 00:17:31.760
avoid falling into the trap of our own biases

472
00:17:32.000 --> 00:17:33.600
because we think we've seen a pattern, but

473
00:17:33.600 --> 00:17:35.640
statistics will give us a hint as to whether

474
00:17:35.640 --> 00:17:36.720
it's really there or not.

475
00:17:37.600 --> 00:17:40.560
Andrew Dunkley: Yeah. Gosh, we could talk forever on this.

476
00:17:41.120 --> 00:17:43.560
It's like opening that can of worms and just

477
00:17:43.560 --> 00:17:45.600
letting it spill out and everybody has a go.

478
00:17:45.950 --> 00:17:47.720
Uh, thank you, Peter. We're going to sort of

479
00:17:47.720 --> 00:17:50.690
continue on to this type of, um, angle, uh,

480
00:17:50.720 --> 00:17:52.400
with a, uh, question from Paul.

481
00:17:53.200 --> 00:17:55.400
Speaker C: G', day, Space nuts. Paul Feen from Sunny

482
00:17:55.400 --> 00:17:58.320
Bridges, Vegas here. Quick question. If

483
00:17:58.320 --> 00:18:01.280
our Earth were to suddenly or not suddenly

484
00:18:01.280 --> 00:18:04.000
become a snowball, as

485
00:18:04.560 --> 00:18:06.640
might have happened if our, uh, scientific

486
00:18:06.640 --> 00:18:09.000
theories are correct, you know, back in our

487
00:18:09.000 --> 00:18:11.800
deep, distant past, what effect

488
00:18:11.800 --> 00:18:14.320
would that have on oxygen levels in our

489
00:18:14.320 --> 00:18:17.120
atmosphere? Would they

490
00:18:17.120 --> 00:18:19.680
stay the same? Uh, would they drop? Because

491
00:18:19.760 --> 00:18:22.080
plants don't grow really well down in

492
00:18:22.080 --> 00:18:24.940
Antarctica. I'd be curious to

493
00:18:24.940 --> 00:18:27.180
know your thoughts on this. Also

494
00:18:27.740 --> 00:18:29.700
what kind of events would actually trigger

495
00:18:29.700 --> 00:18:32.540
that in the first place? Anyway, keep doing a

496
00:18:32.540 --> 00:18:34.300
great job. Whoever happens to be at helm of

497
00:18:34.300 --> 00:18:37.300
the good ship Space Huts, uh, big shout out

498
00:18:37.300 --> 00:18:40.260
to Heidi Campo. Wow, what a great job

499
00:18:40.260 --> 00:18:43.020
he did. Thank you. And Jonti, wherever you

500
00:18:43.020 --> 00:18:45.660
are, uh, would love to hear from you again if

501
00:18:45.660 --> 00:18:48.620
Fred goes off gallivanting over to, I don't

502
00:18:48.620 --> 00:18:51.190
know, Norway or somewhere like that to see

503
00:18:51.190 --> 00:18:53.550
the northern lights. Cheers.

504
00:18:54.350 --> 00:18:56.630
Andrew Dunkley: Thank you, Paul. Well, guess what, that's

505
00:18:56.630 --> 00:18:59.590
exactly what's happened. And uh, Jonti

506
00:18:59.590 --> 00:19:01.870
is with us because of Fred's gallivanting.

507
00:19:02.590 --> 00:19:05.590
So, um, yes, you get to answer Paul's

508
00:19:05.590 --> 00:19:07.550
question about snowball Earth. Uh, the effect

509
00:19:07.550 --> 00:19:10.230
on O2 levels and what sort of, uh, events

510
00:19:10.230 --> 00:19:11.150
would trigger it.

511
00:19:11.470 --> 00:19:13.230
Jonti Horner: That's great. And there's a lot to this and

512
00:19:13.230 --> 00:19:14.630
it's good to hear from a local. So, yeah,

513
00:19:14.630 --> 00:19:16.030
thank you. And hi from.

514
00:19:16.910 --> 00:19:17.910
Andrew Dunkley: You're just up the road.

515
00:19:17.910 --> 00:19:19.310
Jonti Horner: I'm just up the road. Only a couple of

516
00:19:19.310 --> 00:19:21.530
hundred Ks inland. So, yeah, good hear from a

517
00:19:21.530 --> 00:19:24.290
local. This is. This sent me down some

518
00:19:24.290 --> 00:19:25.930
rabbit holes actually. I was digging into

519
00:19:25.930 --> 00:19:27.610
this and it's fascinating. So I've never

520
00:19:27.610 --> 00:19:30.170
actually had that thought of how snowball

521
00:19:30.170 --> 00:19:32.250
Earth episodes could link to oxygen before.

522
00:19:32.490 --> 00:19:34.170
And it's a really, really, really good

523
00:19:34.170 --> 00:19:36.210
question. So almost answer these kind of

524
00:19:36.210 --> 00:19:38.010
things in a bit of reverse order.

525
00:19:39.050 --> 00:19:41.090
The idea is, for those who aren't familiar

526
00:19:41.090 --> 00:19:43.130
with it, that at a couple of occasions in the

527
00:19:43.130 --> 00:19:44.970
past, one a bit more than 2 billion years

528
00:19:44.970 --> 00:19:47.850
ago, 1, 600, 500 million years ago,

529
00:19:48.540 --> 00:19:50.860
the Earth's climate went across a tipping

530
00:19:50.860 --> 00:19:53.620
point and like the ice age began, but the

531
00:19:53.620 --> 00:19:55.820
glaciers just kept advancing and you ended up

532
00:19:55.820 --> 00:19:58.700
with pretty much the entire planet clad in

533
00:19:58.700 --> 00:20:01.620
ice. And conditions at the equator at

534
00:20:01.620 --> 00:20:03.140
that point could even have been colder than

535
00:20:03.140 --> 00:20:05.900
we see in Antarctica right now. So really

536
00:20:05.900 --> 00:20:08.340
kind of dramatic conditions. And that lasted

537
00:20:08.340 --> 00:20:10.660
for a few million, even tens of millions of

538
00:20:10.660 --> 00:20:13.580
years before that condition got broken.

539
00:20:14.180 --> 00:20:16.300
And it makes perfect sense now. The climate

540
00:20:16.300 --> 00:20:18.980
of the, uh, Earth is relatively stable at the

541
00:20:18.980 --> 00:20:20.780
minute. We've just talked about our impact on

542
00:20:20.780 --> 00:20:23.740
it. But, um, on geological timescales, our

543
00:20:23.740 --> 00:20:26.420
climate tends to sit around a fairly stable

544
00:20:26.420 --> 00:20:29.060
point. But what the snowball Earth idea

545
00:20:29.300 --> 00:20:32.140
is reminding us of is that you have a

546
00:20:32.140 --> 00:20:34.540
few possible stable scenarios for the Earth's

547
00:20:34.540 --> 00:20:37.500
climate, of which we are one, we're one,

548
00:20:37.500 --> 00:20:39.570
which is essentially the warm version. But

549
00:20:39.570 --> 00:20:41.370
equally, if you turn the Earth into a

550
00:20:41.370 --> 00:20:44.010
snowball, it will remain a snowball for a

551
00:20:44.010 --> 00:20:46.370
very long time. And uh, the reason for that

552
00:20:46.370 --> 00:20:47.970
is that, uh, if you make the Earth a

553
00:20:47.970 --> 00:20:49.890
snowball, it becomes incredibly More

554
00:20:49.890 --> 00:20:52.730
reflective. And so therefore it absorbs

555
00:20:52.730 --> 00:20:54.890
less energy and so it stays cold. You get

556
00:20:54.890 --> 00:20:56.650
this kind of feedback that keeps the Earth

557
00:20:56.650 --> 00:20:59.490
cold. And the idea is when you flip from one

558
00:20:59.490 --> 00:21:01.250
state to another, you can be locked in that

559
00:21:01.250 --> 00:21:02.770
new state for a very long time until

560
00:21:02.770 --> 00:21:05.530
something changes. Now what could cause

561
00:21:05.530 --> 00:21:08.150
that? One thing that could cause that is

562
00:21:09.110 --> 00:21:11.870
life on our planet. Removing carbon dioxide

563
00:21:11.870 --> 00:21:13.510
from the atmosphere and weathering on the

564
00:21:13.510 --> 00:21:15.350
continents. Removing carbon dioxide from the

565
00:21:15.350 --> 00:21:18.310
atmosphere at, ah, a rate that cools a planet

566
00:21:18.310 --> 00:21:20.230
quicker than the sun getting brighter, warms

567
00:21:20.230 --> 00:21:22.950
a planet. So the sun, when the Earth was very

568
00:21:22.950 --> 00:21:25.630
young, was probably about 30% dimmer. And the

569
00:21:25.630 --> 00:21:28.230
sun is thought to brighten by about 6 or

570
00:21:28.230 --> 00:21:31.070
7% every billion years. So it's 30%

571
00:21:31.070 --> 00:21:32.630
brighter now than it was when the Earth

572
00:21:32.630 --> 00:21:35.100
formed. So the question is, if the sun was so

573
00:21:35.100 --> 00:21:36.820
dim when the Earth was young, how were we

574
00:21:36.820 --> 00:21:38.860
warm enough to have liquid water? And the

575
00:21:38.860 --> 00:21:41.820
answer is, at that point we had a hugely rich

576
00:21:41.820 --> 00:21:43.940
atmosphere of greenhouse gases, things like

577
00:21:43.940 --> 00:21:46.780
carbon dioxide and methane and no oxygen. And

578
00:21:46.780 --> 00:21:48.660
so the atmosphere was very, very rich in

579
00:21:48.660 --> 00:21:50.860
things that would create a really thick doona

580
00:21:51.020 --> 00:21:53.260
and we were very, very pleasantly warm.

581
00:21:54.060 --> 00:21:56.740
Over time, the sun has got brighter, but

582
00:21:56.740 --> 00:21:58.900
life and weathering have removed the

583
00:21:58.900 --> 00:22:01.380
greenhouse gases from the atmosphere and

584
00:22:01.380 --> 00:22:03.540
averaged over the entire age of the Earth,

585
00:22:03.540 --> 00:22:05.540
those two things have roughly balanced out.

586
00:22:06.020 --> 00:22:08.220
And so we still have a temperate climate. Now

587
00:22:08.220 --> 00:22:09.940
if we had the atmosphere the Earth had when

588
00:22:09.940 --> 00:22:12.060
it was young, the Earth would be like Venus

589
00:22:12.060 --> 00:22:13.380
now. The oceans would have boiled and we

590
00:22:13.380 --> 00:22:15.460
wouldn't be having this conversation. Yeah,

591
00:22:16.020 --> 00:22:18.460
but the climate has kind of fortunately

592
00:22:18.460 --> 00:22:21.340
stayed for most of its time in the kind

593
00:22:21.340 --> 00:22:24.220
of warm, stable version. But there have

594
00:22:24.220 --> 00:22:26.340
been these two big occasions that have had

595
00:22:26.340 --> 00:22:29.220
the snowball Earth scenario. Now

596
00:22:29.300 --> 00:22:31.180
there's some debate over, uh, exactly what

597
00:22:31.180 --> 00:22:32.660
triggered that. And it's likely there were a

598
00:22:32.660 --> 00:22:35.260
few things. There was life and increased

599
00:22:35.260 --> 00:22:37.060
weathering, pulling carbon dioxide out of the

600
00:22:37.060 --> 00:22:38.780
atmosphere. So you weaken the greenhouse

601
00:22:38.780 --> 00:22:41.780
effect and cool the planet down. That is

602
00:22:41.780 --> 00:22:44.339
most likely. You also have a scenario,

603
00:22:44.339 --> 00:22:46.660
incidentally, where if you make the Earth

604
00:22:46.660 --> 00:22:49.500
more reflective around the equator, you lower

605
00:22:49.500 --> 00:22:51.020
the amount of heat that's absorbed by the

606
00:22:51.020 --> 00:22:52.540
Earth, increase the amount reflected and you

607
00:22:52.540 --> 00:22:54.720
cool the Earth as well. So what are the

608
00:22:54.720 --> 00:22:56.800
scenarios that's proposed to explain how we

609
00:22:56.800 --> 00:22:59.560
got into the snowball Earth periods? At first

610
00:22:59.880 --> 00:23:01.840
was that you got a period where you got one

611
00:23:01.840 --> 00:23:03.360
of these supercontinents where all the

612
00:23:03.360 --> 00:23:04.920
continental material on the Earth kind of

613
00:23:04.920 --> 00:23:07.360
smushed together, like we had with Pangea,

614
00:23:07.360 --> 00:23:09.120
like was proposed with Pangaea. Previous

615
00:23:09.120 --> 00:23:11.840
episode of that. We have most of the Earth's

616
00:23:11.840 --> 00:23:14.280
continents around the Earth's, uh, equator,

617
00:23:15.480 --> 00:23:17.600
continental material, rock and, um,

618
00:23:17.800 --> 00:23:19.600
vegetation and everything else is more

619
00:23:19.600 --> 00:23:21.950
reflective than water. And in fact, most of

620
00:23:21.950 --> 00:23:24.250
the energy coming into the Earth these, ah,

621
00:23:24.470 --> 00:23:26.350
days is absorbed by the water. The water is

622
00:23:26.350 --> 00:23:27.990
the main thing that locks in the heat and

623
00:23:27.990 --> 00:23:30.390
keeps us warm. And that, of course, is why

624
00:23:30.470 --> 00:23:32.150
Brisbane gets so warm and humid in the

625
00:23:32.150 --> 00:23:34.510
summers. It's why Western Europe is so

626
00:23:34.510 --> 00:23:36.950
pleasant in the winters compared to the

627
00:23:36.950 --> 00:23:39.150
middle of Canada. The water carries a lot of

628
00:23:39.150 --> 00:23:41.590
heat, holds onto it for a long, long time. So

629
00:23:41.590 --> 00:23:43.830
you have this speculative scenario where

630
00:23:44.710 --> 00:23:46.510
all the continents end up smushed up and near

631
00:23:46.510 --> 00:23:48.430
the Earth's equator. So the Earth's albedo

632
00:23:48.430 --> 00:23:50.800
gets more reflective, a higher

633
00:23:50.800 --> 00:23:53.040
albedo, so the Earth would naturally cool

634
00:23:53.040 --> 00:23:54.440
because it's absorbing less heat and

635
00:23:54.440 --> 00:23:57.000
reflecting more. Added to which, if you put

636
00:23:57.000 --> 00:23:58.880
the continents nearer the equator, you're in

637
00:23:58.880 --> 00:24:00.800
a location which gets much higher rainfall

638
00:24:00.800 --> 00:24:03.080
and much higher weather levels because the

639
00:24:03.080 --> 00:24:05.040
water at that latitude is hotter, so

640
00:24:05.040 --> 00:24:06.960
evaporates more. The atmosphere can hold more

641
00:24:06.960 --> 00:24:09.280
water, so you get more weathering, which

642
00:24:09.280 --> 00:24:11.200
drives more chemistry, which also acts to

643
00:24:11.200 --> 00:24:12.560
pull more carbon dioxide out of the

644
00:24:12.560 --> 00:24:14.880
atmosphere. And, um, that exacerbates this

645
00:24:14.880 --> 00:24:17.170
and we, you know, removes the greenhouse

646
00:24:17.170 --> 00:24:19.410
effect as well. So you've got more energy

647
00:24:19.410 --> 00:24:21.210
being reflected and less absorbed. So the

648
00:24:21.210 --> 00:24:23.530
Earth cools more carbon dioxide pulled out of

649
00:24:23.530 --> 00:24:25.170
the atmosphere, so the greenhouse effect

650
00:24:25.170 --> 00:24:28.170
weakens, so the Earth cools. That then

651
00:24:28.170 --> 00:24:30.290
causes the Earth to start entering ice ages

652
00:24:30.290 --> 00:24:32.690
where the water near the poles freezes and

653
00:24:32.690 --> 00:24:35.450
the ice expands towards the equator. That

654
00:24:35.450 --> 00:24:37.730
ice is more reflective than the water that it

655
00:24:37.730 --> 00:24:40.330
sits on is. So less energy is absorbed and

656
00:24:40.330 --> 00:24:42.130
more is reflected. And so the Earth cools.

657
00:24:42.130 --> 00:24:44.430
And so you get this feedback effect where the

658
00:24:44.430 --> 00:24:46.070
ice gradually reaches down towards the

659
00:24:46.070 --> 00:24:48.150
equator. And once you're in that scenario,

660
00:24:48.630 --> 00:24:50.670
you're in a position where even if you put

661
00:24:50.670 --> 00:24:52.030
all the carbon dioxide back in the

662
00:24:52.030 --> 00:24:54.550
atmosphere, the Earth is so reflective that

663
00:24:54.550 --> 00:24:57.390
it will stay cold. You're locked into this

664
00:24:57.390 --> 00:25:00.350
other stable state. However, longer

665
00:25:00.350 --> 00:25:02.030
term, what happens is that, uh, you've got

666
00:25:02.030 --> 00:25:04.230
the ice sheet now sat over all of the rocks.

667
00:25:04.710 --> 00:25:06.590
So you prevent the weathering that was

668
00:25:06.590 --> 00:25:08.550
removing carbon dioxide from the atmosphere.

669
00:25:08.550 --> 00:25:11.280
You turn that off, you've still got things

670
00:25:11.280 --> 00:25:12.560
putting carbon dioxide back in the

671
00:25:12.560 --> 00:25:12.960
atmosphere.

672
00:25:12.960 --> 00:25:14.800
You've still got volcanoes erupting and all

673
00:25:14.800 --> 00:25:17.440
the sources of gases that were putting it

674
00:25:17.440 --> 00:25:18.800
back into the atmosphere and eventually

675
00:25:18.800 --> 00:25:20.800
return the weather, material, weather gases

676
00:25:20.800 --> 00:25:22.600
into the atmosphere. So you're in the

677
00:25:22.600 --> 00:25:24.400
snowball, uh, Earth setup. But gradually over

678
00:25:24.400 --> 00:25:26.760
time, then your greenhouse gas levels rise

679
00:25:26.760 --> 00:25:29.280
and rise and rise until eventually you start

680
00:25:29.280 --> 00:25:31.680
to melt the ice and you get this other

681
00:25:31.680 --> 00:25:34.360
tipping point where suddenly you're warm

682
00:25:34.360 --> 00:25:37.000
enough for the ice to melt and retreat, which

683
00:25:37.000 --> 00:25:39.680
means you expose more water, more water is

684
00:25:39.680 --> 00:25:42.080
exposed, which means more area to absorb the

685
00:25:42.080 --> 00:25:43.480
heat, which means the Earth will warm up

686
00:25:43.480 --> 00:25:45.600
more, which means more ice melts, and you go

687
00:25:45.600 --> 00:25:48.080
back to being this kind of warmer, uh, Earth.

688
00:25:49.200 --> 00:25:51.400
That brings with it, though, a time when

689
00:25:51.400 --> 00:25:53.280
you've had the continents crunched up under

690
00:25:53.280 --> 00:25:56.040
ice sheets, broken up into kind of gravelly

691
00:25:56.040 --> 00:25:58.120
small bits of debris. And then when you start

692
00:25:58.120 --> 00:26:00.480
raining on that again, you get a huge amount

693
00:26:00.480 --> 00:26:02.890
of weathering water washing out

694
00:26:03.210 --> 00:26:04.970
minerals and putting it into the ocean.

695
00:26:06.010 --> 00:26:07.930
And that means that suddenly all that life

696
00:26:07.930 --> 00:26:09.770
that has been starved through the snowball

697
00:26:09.770 --> 00:26:12.330
Earth epoch is suddenly going, hey, look, the

698
00:26:12.330 --> 00:26:13.810
Earth's nice and warm. It's a nice place to

699
00:26:13.810 --> 00:26:16.330
live again. Brilliant. And, oh, look, there's

700
00:26:16.330 --> 00:26:18.770
suddenly all this food in the oceans. And so

701
00:26:18.770 --> 00:26:20.970
the papers that I came across when I was

702
00:26:20.970 --> 00:26:22.930
looking into this as a result of Paul's

703
00:26:22.930 --> 00:26:25.890
question, it seems that after both of the big

704
00:26:25.890 --> 00:26:27.890
snowball Earth eras, there was a massive

705
00:26:27.890 --> 00:26:30.340
oxygenation event on Earth. So after the

706
00:26:30.340 --> 00:26:32.020
first one, you went from effectively no

707
00:26:32.020 --> 00:26:34.340
oxygen in Earth's atmosphere to Earth's

708
00:26:34.340 --> 00:26:35.700
atmosphere being about 2%

709
00:26:36.660 --> 00:26:38.860
oxygen, which is a big jump from nothing to

710
00:26:38.860 --> 00:26:40.660
2%. And, um, then

711
00:26:41.380 --> 00:26:43.860
6,500 million years ago,

712
00:26:44.180 --> 00:26:46.500
you had the end of the most recent snowball

713
00:26:46.500 --> 00:26:47.940
Earth thing, and you got another mass

714
00:26:47.940 --> 00:26:50.900
oxygenation event. Why suddenly you've

715
00:26:50.900 --> 00:26:52.460
got all this nutrient and all this stuff

716
00:26:52.460 --> 00:26:55.020
washing off into the oceans, prime conditions

717
00:26:55.020 --> 00:26:57.480
for things to grow and a huge amount of

718
00:26:57.480 --> 00:27:00.000
oxygen released. And, um, that is thought to

719
00:27:00.000 --> 00:27:01.640
have been what drove oxygen up to something

720
00:27:01.640 --> 00:27:04.280
comparable to its current levels relatively

721
00:27:04.280 --> 00:27:07.160
quickly. And that then led to there

722
00:27:07.160 --> 00:27:09.040
being sufficient free evidence for what's

723
00:27:09.040 --> 00:27:10.520
called, I think, the Cambrian explosion,

724
00:27:10.520 --> 00:27:13.200
where suddenly you've got an Earth that has

725
00:27:13.200 --> 00:27:16.080
all these different niches suddenly freed up

726
00:27:16.400 --> 00:27:18.400
and the source of ready oxygen, and

727
00:27:18.400 --> 00:27:20.920
everything goes crazy evolving to fill the

728
00:27:20.920 --> 00:27:23.700
available opportunities. And

729
00:27:23.700 --> 00:27:26.060
so all of that kind of gives you an idea how

730
00:27:26.060 --> 00:27:27.700
we think snowball Earth episodes could

731
00:27:27.700 --> 00:27:30.220
happen. And, um, what would happen to oxygen

732
00:27:30.220 --> 00:27:32.540
afterwards? Which seems to be the accepted

733
00:27:32.540 --> 00:27:34.500
scientific wisdom, that after a snowball

734
00:27:34.500 --> 00:27:36.660
Earth episode, when it ends, you can get the

735
00:27:36.660 --> 00:27:38.699
oxygen suddenly getting significantly more

736
00:27:38.699 --> 00:27:41.220
oxygen rich as life takes advantage of the

737
00:27:41.220 --> 00:27:43.900
new conditions. What would happen to

738
00:27:43.900 --> 00:27:45.820
oxygen now that there's a lot of it in the

739
00:27:45.820 --> 00:27:47.980
atmosphere during the snowball Earth period,

740
00:27:47.980 --> 00:27:50.840
I couldn't find any speculation on. So

741
00:27:50.840 --> 00:27:52.520
it's a really interesting question. Now, it

742
00:27:52.520 --> 00:27:54.080
doesn't mean there's no speculation out

743
00:27:54.080 --> 00:27:55.760
there. It just means that I couldn't find any

744
00:27:55.760 --> 00:27:58.720
of his. Big difference there. But

745
00:27:58.720 --> 00:28:00.200
there's a few things that are going on that I

746
00:28:00.200 --> 00:28:02.520
think could be interesting. Firstly, there's

747
00:28:02.520 --> 00:28:04.560
a huge amount of oxygen in the atmosphere. So

748
00:28:04.560 --> 00:28:07.240
even if you stop producing it and you manage

749
00:28:07.240 --> 00:28:09.680
to keep alive the things that use it, it will

750
00:28:09.680 --> 00:28:11.480
probably go down very slowly just because

751
00:28:11.480 --> 00:28:13.520
there's uh, so much of it. And if you were

752
00:28:13.520 --> 00:28:16.210
killing off a lot of life, then

753
00:28:16.290 --> 00:28:18.450
to be honest, there's not as much using it

754
00:28:18.450 --> 00:28:21.290
anyway. Volcanoes erupting, carbon

755
00:28:21.290 --> 00:28:23.610
dioxide and particularly methane that's been

756
00:28:23.610 --> 00:28:26.170
erupted and outgassed, um, particularly

757
00:28:26.170 --> 00:28:28.890
towards the end of the ice age kind of

758
00:28:28.890 --> 00:28:31.290
period, getting lots of methane released into

759
00:28:31.290 --> 00:28:33.090
the atmosphere would remove the oxygen as the

760
00:28:33.090 --> 00:28:34.810
methane and the oxygen interact with each

761
00:28:34.810 --> 00:28:37.010
other. And if that was happening quicker than

762
00:28:37.010 --> 00:28:38.690
life was putting new oxygen into the

763
00:28:38.690 --> 00:28:40.890
atmosphere, then you can imagine that leading

764
00:28:40.890 --> 00:28:42.890
to a bit of a dip in the amount of oxygen in

765
00:28:42.890 --> 00:28:45.650
the atmosphere at the time. But my

766
00:28:45.650 --> 00:28:47.730
guess would be that probably during the

767
00:28:47.730 --> 00:28:50.490
snowball Earth period, the oxygen levels

768
00:28:50.490 --> 00:28:52.170
wouldn't change all that much. You might be

769
00:28:52.170 --> 00:28:54.050
producing less oxygen, but you'd also be

770
00:28:54.050 --> 00:28:56.490
using less. So that will balance out. But

771
00:28:56.490 --> 00:28:59.090
what you would get over time is, particularly

772
00:28:59.090 --> 00:29:01.610
if you killed off a lot of life, you get this

773
00:29:01.610 --> 00:29:04.210
slow, steady increase in

774
00:29:04.210 --> 00:29:06.450
greenhouse gas levels because you're still

775
00:29:06.450 --> 00:29:07.930
pumping out the same amount in terms of

776
00:29:07.930 --> 00:29:10.170
volcanism, but you've removed the weathering

777
00:29:10.170 --> 00:29:12.810
that's taking it away again. And so that

778
00:29:12.810 --> 00:29:15.370
would lead to the greenhouse gas level rising

779
00:29:15.370 --> 00:29:17.970
slowly over time until it got to the point

780
00:29:17.970 --> 00:29:19.570
where it turned it back over the tipping

781
00:29:19.570 --> 00:29:21.730
point and allowed the Earth to warm up again.

782
00:29:21.730 --> 00:29:23.490
And that will probably then be a very bad

783
00:29:23.490 --> 00:29:25.010
thing because the sun is now much more

784
00:29:25.010 --> 00:29:26.810
luminous than it ever has been in the past.

785
00:29:27.450 --> 00:29:29.690
If you get a runaway greenhouse effect now,

786
00:29:30.170 --> 00:29:32.410
that's a lot more problematic than it was 500

787
00:29:32.410 --> 00:29:34.210
million years ago. And maybe that could lead

788
00:29:34.210 --> 00:29:37.210
to conditions where you don't hit our current

789
00:29:37.680 --> 00:29:39.800
stable level, but you go past that and you

790
00:29:39.800 --> 00:29:42.600
end up hurrying the end of the Earth, uh, as

791
00:29:42.600 --> 00:29:43.840
a habitable world, effectively.

792
00:29:44.080 --> 00:29:45.600
Andrew Dunkley: Oh, fun. Yeah.

793
00:29:45.680 --> 00:29:46.640
Jonti Horner: Careful path.

794
00:29:47.760 --> 00:29:48.720
Andrew Dunkley: I, uh, just did a.

795
00:29:50.880 --> 00:29:53.170
I'll get some negative press for this, but,

796
00:29:53.170 --> 00:29:55.520
uh, I just did a, um, put uh, a question into

797
00:29:55.520 --> 00:29:58.240
chat. GPT Would, uh, current

798
00:29:58.240 --> 00:30:00.400
oxygen levels on Earth reduce if Earth were

799
00:30:00.400 --> 00:30:02.560
to freeze over? And uh, it's come up with a

800
00:30:02.560 --> 00:30:05.010
few scenarios, but basically says most, he

801
00:30:05.010 --> 00:30:07.770
he. It says most oxygen on Earth comes from

802
00:30:07.770 --> 00:30:10.450
photosynthetic organisms, uh, mainly

803
00:30:10.450 --> 00:30:12.570
marine plankton and land plants. If Earth

804
00:30:12.570 --> 00:30:15.570
froze over ocean, uh, uh, surfaces would

805
00:30:15.570 --> 00:30:17.330
be sealed under thick ice, preventing

806
00:30:17.330 --> 00:30:19.370
sunlight from reaching most marine

807
00:30:19.370 --> 00:30:22.170
photosynthesizers. Land plants would die or

808
00:30:22.170 --> 00:30:24.250
go dormant due to cold or lack of liquid

809
00:30:24.250 --> 00:30:27.170
water. So oxygen production would drop

810
00:30:27.170 --> 00:30:27.850
dramatically.

811
00:30:28.490 --> 00:30:30.690
Jonti Horner: And that makes sense, but I'd argue that

812
00:30:30.690 --> 00:30:32.610
oxygen use will drop dramatically as well

813
00:30:32.610 --> 00:30:33.930
because you kill the things that are using

814
00:30:33.930 --> 00:30:36.250
the oxygen. Yes. The other thing that I've

815
00:30:36.250 --> 00:30:37.870
stumb across in my reading actually, and that

816
00:30:37.870 --> 00:30:40.510
just reminded me of was one of the things

817
00:30:40.510 --> 00:30:42.630
that tied into this idea of the snowball

818
00:30:42.630 --> 00:30:44.590
earth stuff was how on earth did life make it

819
00:30:44.590 --> 00:30:46.710
through. And um, one of the things that

820
00:30:46.710 --> 00:30:48.470
people's modeling found was that even though

821
00:30:48.470 --> 00:30:50.030
you'd get ice all the way down to the

822
00:30:50.030 --> 00:30:52.870
equator, the processes that happen

823
00:30:52.950 --> 00:30:54.910
at uh, the equator will probably prevent that

824
00:30:54.910 --> 00:30:56.950
ice being more than about 10 meters thick.

825
00:30:57.110 --> 00:30:58.790
And uh, studies have shown that enough light

826
00:30:58.790 --> 00:31:00.910
can make it through ice for photosynthesis to

827
00:31:00.910 --> 00:31:03.830
continue unless the ice is 20 meters thick

828
00:31:03.830 --> 00:31:06.260
or more. And so there'd likely be a band

829
00:31:06.260 --> 00:31:08.140
where you could continue photosynthesis under

830
00:31:08.140 --> 00:31:09.820
the ice because the ice is not thick enough

831
00:31:09.820 --> 00:31:12.060
to block all the sunlight. That seemed to be

832
00:31:12.060 --> 00:31:14.140
the argument. There was some discussions of

833
00:31:14.380 --> 00:31:16.340
where the pockets of life holding on through

834
00:31:16.340 --> 00:31:19.020
the hellish times would be and that was quite

835
00:31:19.020 --> 00:31:20.300
interesting. But like I said, I'm not a

836
00:31:20.300 --> 00:31:22.900
biologist, so uh, that is straining my

837
00:31:22.900 --> 00:31:24.740
expertise to look at exactly how life would

838
00:31:24.740 --> 00:31:25.900
adapt to those conditions.

839
00:31:26.620 --> 00:31:28.580
Andrew Dunkley: Indeed. All right, Paul, thanks for the

840
00:31:28.580 --> 00:31:30.980
question. Great one. And uh, there might be

841
00:31:30.980 --> 00:31:33.530
more to talk about that, uh, in regard to

842
00:31:33.530 --> 00:31:35.970
that down the track. This is Space Nuts with

843
00:31:35.970 --> 00:31:38.570
Andrew Dunkley and Jonti Horner.

844
00:31:41.450 --> 00:31:43.690
Speaker C: Three, two, one.

845
00:31:44.330 --> 00:31:45.530
Jonti Horner: Space Nuts.

846
00:31:45.770 --> 00:31:47.730
Andrew Dunkley: Now Jonti, uh, a couple of questions have

847
00:31:47.730 --> 00:31:50.090
come in about uh, objects or

848
00:31:50.330 --> 00:31:52.890
events that have happened in space.

849
00:31:53.340 --> 00:31:55.840
Uh, Casey has messaged, um,

850
00:31:56.290 --> 00:31:58.650
us. Hello again, this is Casey from Colorado.

851
00:31:58.650 --> 00:32:01.210
I recently read a little bit about the record

852
00:32:01.210 --> 00:32:03.705
breaking KM M32302

853
00:32:04.004 --> 00:32:06.790
213A. Please correct me

854
00:32:06.790 --> 00:32:09.670
if I'm wrong, but detecting a 220

855
00:32:10.150 --> 00:32:12.870
PETA electron volt neutrino

856
00:32:12.950 --> 00:32:15.270
is pretty crazy considering that

857
00:32:15.510 --> 00:32:18.030
that's like 30 times more energetic than the

858
00:32:18.030 --> 00:32:20.310
previous record holder. Uh, what could

859
00:32:20.310 --> 00:32:22.990
possibly be its source? Love the podcast and

860
00:32:22.990 --> 00:32:25.950
hope you're both well. Thanks from Casey in

861
00:32:25.950 --> 00:32:27.470
Colorado and she hopes you're well too,

862
00:32:27.470 --> 00:32:27.990
Jonti.

863
00:32:29.430 --> 00:32:29.910
Speaker C: Yes.

864
00:32:29.910 --> 00:32:31.630
Andrew Dunkley: Then again she might be talking about Fred

865
00:32:31.630 --> 00:32:32.710
and Heidi. I don't know.

866
00:32:36.090 --> 00:32:37.970
Jonti Horner: So this is a really interesting one. I must

867
00:32:37.970 --> 00:32:40.250
say that I hadn't seen this announcement and

868
00:32:40.490 --> 00:32:42.530
so this was a really interesting thing to

869
00:32:42.530 --> 00:32:44.970
read about. Um, this is a neutrino that

870
00:32:45.130 --> 00:32:47.690
according to the name was seen in 2023,

871
00:32:47.930 --> 00:32:50.610
on February 13th. And, um, it was

872
00:32:50.610 --> 00:32:53.450
detected by this huge array of

873
00:32:53.450 --> 00:32:55.330
detectors on the bottom of the Mediterranean

874
00:32:55.330 --> 00:32:58.050
Ocean, Mediterranean Sea, about 3 and a half

875
00:32:58.050 --> 00:33:00.530
kilometers below sea level, in the pitch

876
00:33:00.530 --> 00:33:02.730
black of the deep ocean, where they have all

877
00:33:02.730 --> 00:33:05.370
these detectors that have the job of

878
00:33:05.370 --> 00:33:07.570
detecting incredibly faint flashes of light

879
00:33:08.050 --> 00:33:10.930
that occur when cosmic rays or neutrinos

880
00:33:11.410 --> 00:33:14.410
collide with an atom in the ocean and cause

881
00:33:14.410 --> 00:33:16.970
a cascade of light as this whole collision

882
00:33:16.970 --> 00:33:19.530
chain of, uh, particles being formed and

883
00:33:19.530 --> 00:33:21.530
energy being released as the energy from

884
00:33:21.530 --> 00:33:24.170
those things is dumped into the ocean. And

885
00:33:24.170 --> 00:33:26.370
this occurred before they'd finished building

886
00:33:26.370 --> 00:33:28.170
and testing this array. So it was during the

887
00:33:28.170 --> 00:33:30.220
testing phase, and it is

888
00:33:30.860 --> 00:33:32.980
reliably says on all of these websites, by

889
00:33:32.980 --> 00:33:35.420
far the most energetic neutrino ever

890
00:33:35.420 --> 00:33:38.300
detected. And it is so energetic

891
00:33:38.780 --> 00:33:41.260
that there is no source within our galaxy

892
00:33:41.660 --> 00:33:44.380
that could generate a neutrino that energetic

893
00:33:44.380 --> 00:33:46.940
that we know of. And if it had been generated

894
00:33:46.940 --> 00:33:48.860
by something nearby, we'd have seen other

895
00:33:48.860 --> 00:33:50.740
things happening. You might have seen a very

896
00:33:50.740 --> 00:33:53.620
powerful gamma ray burst or something like

897
00:33:53.620 --> 00:33:56.590
that. And, uh, no counterpart was detected.

898
00:33:56.590 --> 00:33:58.470
There was nothing that happened at this time

899
00:33:59.190 --> 00:34:01.510
that synced up with when this happened. Now

900
00:34:01.590 --> 00:34:03.150
should be said that when I search for this,

901
00:34:03.150 --> 00:34:04.990
there's a nice little article describing it

902
00:34:04.990 --> 00:34:07.750
by the Astrobytes website, which is

903
00:34:07.750 --> 00:34:10.590
a website run by graduate students in

904
00:34:10.590 --> 00:34:13.510
astrophysics in the US that tries to be a

905
00:34:13.510 --> 00:34:16.270
literature review journal club for

906
00:34:16.270 --> 00:34:18.590
other graduate students and, um, to give

907
00:34:18.590 --> 00:34:20.550
students an opportunity to practice science

908
00:34:20.550 --> 00:34:22.070
writing about things out of their field. And

909
00:34:22.070 --> 00:34:23.850
there's a bit of a description of it. There's

910
00:34:24.250 --> 00:34:25.800
um, and that's a nice little website if

911
00:34:25.800 --> 00:34:27.520
you're interested in getting a little

912
00:34:27.520 --> 00:34:29.680
snapshot summary of research papers to try

913
00:34:29.680 --> 00:34:32.400
and do one a day. But I also stumbled

914
00:34:32.400 --> 00:34:34.960
across the official page for this event,

915
00:34:35.440 --> 00:34:37.520
which is published by the network

916
00:34:38.320 --> 00:34:40.720
that are running these detectors. And that's

917
00:34:40.720 --> 00:34:42.720
got a lovely little YouTube Music video right

918
00:34:42.720 --> 00:34:44.200
at the top that you can watch. It's about two

919
00:34:44.200 --> 00:34:46.320
and a half minutes long that describes this

920
00:34:46.320 --> 00:34:48.400
thing, how it's detected, and some of the

921
00:34:48.400 --> 00:34:50.480
possible suggestions for its formation. Now,

922
00:34:51.820 --> 00:34:54.780
going beyond that to what could have created

923
00:34:54.780 --> 00:34:57.700
it is really pushing beyond the bounds of my

924
00:34:57.700 --> 00:34:59.900
knowledge and expertise. So I'm afraid,

925
00:35:00.060 --> 00:35:01.700
Casey, you're going to have to accept a

926
00:35:01.700 --> 00:35:04.260
journeyman's explanation based on what I was

927
00:35:04.260 --> 00:35:07.180
able to read around about this, which digs

928
00:35:07.180 --> 00:35:08.820
into things that I honestly don't fully

929
00:35:08.820 --> 00:35:11.340
understand. But the argument is, because of

930
00:35:11.340 --> 00:35:13.540
the incredibly high energy of this thing, it

931
00:35:13.540 --> 00:35:15.940
couldn't have been generated locally. And

932
00:35:15.940 --> 00:35:18.550
that points to an origin in the very distant

933
00:35:18.550 --> 00:35:20.630
and therefore very early universe.

934
00:35:21.350 --> 00:35:24.270
Now, there's some theories that fall

935
00:35:24.270 --> 00:35:25.830
under the branch of what I think is called

936
00:35:25.830 --> 00:35:28.550
quantum field theory that talk

937
00:35:28.630 --> 00:35:31.430
about there being photon

938
00:35:31.430 --> 00:35:34.430
fields permeating space. And

939
00:35:34.430 --> 00:35:35.710
I don't fully understand what that is and

940
00:35:35.710 --> 00:35:38.710
what that means, in all honesty. But

941
00:35:38.710 --> 00:35:41.030
the idea seems to be here that you've got

942
00:35:41.030 --> 00:35:42.790
radiation from the cosmic microwave

943
00:35:42.790 --> 00:35:44.430
background, or from very early in the

944
00:35:44.430 --> 00:35:47.400
universe that includes incredibly high energy

945
00:35:47.720 --> 00:35:49.480
radiation at, uh, that time,

946
00:35:50.920 --> 00:35:52.720
because that's a heat from the big Bang. Now,

947
00:35:52.720 --> 00:35:54.680
nowadays we see that as a cosmic microwave

948
00:35:54.680 --> 00:35:56.760
background. It's very low energy levels

949
00:35:56.760 --> 00:35:59.200
because it's been redshifted. But at the

950
00:35:59.200 --> 00:36:01.039
time, the energy levels were incredibly,

951
00:36:01.039 --> 00:36:02.920
incredibly high. And that means that these

952
00:36:03.400 --> 00:36:05.930
photon fields, if you follow the, um,

953
00:36:05.960 --> 00:36:08.640
quantum field theory ideas, were incredibly

954
00:36:08.640 --> 00:36:11.320
intense. Now, one of the ways that you can

955
00:36:11.320 --> 00:36:13.960
produce neutrinos that is predicted by this

956
00:36:14.720 --> 00:36:16.400
predicts what are called cosmogenic

957
00:36:16.400 --> 00:36:19.160
neutrinos. Now, it should be said that

958
00:36:19.160 --> 00:36:21.040
none of these have ever been detected until

959
00:36:21.120 --> 00:36:23.600
potentially this one. But it's one of the

960
00:36:23.600 --> 00:36:26.000
predictions that quantum field theory makes

961
00:36:26.400 --> 00:36:28.320
is that you should see these cosmogenic

962
00:36:28.320 --> 00:36:31.120
neutrinos that are generated by

963
00:36:31.120 --> 00:36:33.640
cosmic radiation rather than a specific event

964
00:36:33.640 --> 00:36:35.920
like a gamma ray burst or a supernova or

965
00:36:35.920 --> 00:36:38.440
something like that. And the idea is that in

966
00:36:38.440 --> 00:36:39.920
the very early universe, you've got these

967
00:36:39.920 --> 00:36:42.680
incredibly high amounts of energy. And that

968
00:36:42.680 --> 00:36:45.240
means that these photon fields, I think

969
00:36:45.240 --> 00:36:47.600
they're called, can interact with

970
00:36:47.840 --> 00:36:50.360
particles of matter. And, um, when you get

971
00:36:50.360 --> 00:36:52.720
this interaction, that can lead to the

972
00:36:52.720 --> 00:36:54.400
production of an incredibly high energy

973
00:36:54.400 --> 00:36:57.320
neutrino. Now, the very high energy

974
00:36:57.320 --> 00:37:00.230
neutrino, as we know, neutrinos, are,

975
00:37:00.230 --> 00:37:03.120
uh, about the weakest interacting things we

976
00:37:03.120 --> 00:37:06.040
know of. So once you produce a very high

977
00:37:06.040 --> 00:37:08.440
energy neutrino that can pass across the

978
00:37:08.440 --> 00:37:10.520
entire universe without interacting with

979
00:37:10.520 --> 00:37:12.620
anything, we've got millions of these things

980
00:37:12.620 --> 00:37:14.220
passing through our bodies as we speak, and

981
00:37:14.220 --> 00:37:16.300
we just don't feel them. Which incidentally,

982
00:37:16.300 --> 00:37:17.900
is why to detect them, you want to be at the

983
00:37:17.900 --> 00:37:19.980
bottom of the ocean or in a huge volume of

984
00:37:19.980 --> 00:37:22.300
water so that you maximize the number of

985
00:37:22.300 --> 00:37:24.540
atoms available for one of these to by chance

986
00:37:24.540 --> 00:37:26.300
collide with and give you the light show.

987
00:37:26.940 --> 00:37:28.740
Because you need a huge volume of water to

988
00:37:28.740 --> 00:37:30.660
get even one neutrino to hit something and

989
00:37:30.660 --> 00:37:32.020
give you a show, because they're that weakly

990
00:37:32.020 --> 00:37:32.620
interacting.

991
00:37:32.700 --> 00:37:33.180
Andrew Dunkley: Yeah.

992
00:37:33.260 --> 00:37:35.500
Jonti Horner: Once you produce these cosmogenic neutrinos,

993
00:37:35.500 --> 00:37:37.180
they then carry on through the universe

994
00:37:37.180 --> 00:37:39.760
forevermore at ridiculously high energies.

995
00:37:40.400 --> 00:37:42.680
Now, the bit I quite honestly don't

996
00:37:42.680 --> 00:37:44.120
understand with this, and none of the things

997
00:37:44.120 --> 00:37:46.920
I've read have been able to explain to me is

998
00:37:46.920 --> 00:37:49.840
the fact that uh, if this thing was

999
00:37:49.840 --> 00:37:52.480
created with the cosmic microwave

1000
00:37:52.480 --> 00:37:55.040
background, I would have thought it should be

1001
00:37:55.360 --> 00:37:57.600
redshifted by the expansion of the universe

1002
00:37:58.000 --> 00:38:00.860
in the same way that photons are uh,

1003
00:38:00.960 --> 00:38:03.400
the light we see it. And doing a bit of

1004
00:38:03.400 --> 00:38:05.200
reading around it does seem that neutrinos

1005
00:38:05.200 --> 00:38:07.440
can be gravitationally redshifted. So if you

1006
00:38:07.440 --> 00:38:09.200
get a neutrino produced at the surface of a

1007
00:38:09.200 --> 00:38:12.140
neutron star, that is one energy, by the

1008
00:38:12.140 --> 00:38:13.900
time it escapes from the neutron star's

1009
00:38:13.900 --> 00:38:15.340
gravity, it's lost energy and it's

1010
00:38:15.340 --> 00:38:18.180
effectively redshifted. What I haven't been

1011
00:38:18.180 --> 00:38:19.500
able to find out though is whether the

1012
00:38:19.500 --> 00:38:22.420
expansion of the universe would redshift

1013
00:38:22.420 --> 00:38:25.380
neutrinos and therefore lower their energy.

1014
00:38:26.420 --> 00:38:29.140
Now if the expansion of the

1015
00:38:29.140 --> 00:38:31.100
universe doesn't lower the energies then this

1016
00:38:31.100 --> 00:38:32.980
makes perfect sense. You know, you've got

1017
00:38:32.980 --> 00:38:34.900
this incredibly high energy neutrino that's

1018
00:38:34.900 --> 00:38:36.700
tied to how high the energies were when the

1019
00:38:36.700 --> 00:38:39.140
universe was young and it's only just reached

1020
00:38:39.140 --> 00:38:42.060
us now. If they are redshifted then

1021
00:38:42.060 --> 00:38:44.300
that makes this even more head scratchingly

1022
00:38:44.300 --> 00:38:46.580
awesome because if it has been

1023
00:38:46.580 --> 00:38:48.740
redshifted and its energy dropped by an

1024
00:38:48.740 --> 00:38:51.580
incredible amount and it's still 220peta

1025
00:38:51.580 --> 00:38:54.020
electron volts, what was its energy when it

1026
00:38:54.020 --> 00:38:56.500
was formed? And I just don't fully understand

1027
00:38:56.500 --> 00:38:58.820
that. So my knowledge is limited of this.

1028
00:38:59.540 --> 00:39:01.300
I've done my best to read around it and get

1029
00:39:01.300 --> 00:39:02.940
an understanding of what they think is going

1030
00:39:02.940 --> 00:39:05.820
on. But I guess what

1031
00:39:05.820 --> 00:39:08.140
comes out of this for me a, it's just a very

1032
00:39:08.140 --> 00:39:11.060
cool detection. But if you want to push

1033
00:39:11.060 --> 00:39:12.620
the boundaries of what we know and build

1034
00:39:12.620 --> 00:39:15.300
theories of how the universe works, our

1035
00:39:15.300 --> 00:39:17.900
theories will eventually go

1036
00:39:17.900 --> 00:39:20.020
beyond our level to observe the things that

1037
00:39:20.020 --> 00:39:22.940
they predict. A good example of this I always

1038
00:39:22.940 --> 00:39:24.980
go back to because it's my own wheelhouse, is

1039
00:39:24.980 --> 00:39:27.620
Newton's theories of gravitation which he

1040
00:39:27.620 --> 00:39:30.260
published in like in Principia Mathematica in

1041
00:39:30.260 --> 00:39:33.240
1680, 1682. Around then, um, and that

1042
00:39:33.240 --> 00:39:35.240
gave us mathematical tools that allowed us to

1043
00:39:35.240 --> 00:39:37.480
work how things moved in gravitational

1044
00:39:37.480 --> 00:39:39.560
fields, allowed us to work out orbits and

1045
00:39:39.560 --> 00:39:40.960
predict things in the future. And that's been

1046
00:39:40.960 --> 00:39:43.160
incredibly powerful. By the

1047
00:39:43.160 --> 00:39:46.080
1800s observations were

1048
00:39:46.080 --> 00:39:48.440
starting to show that the orbit of Mercury

1049
00:39:48.840 --> 00:39:51.280
was behaving slightly different to how

1050
00:39:51.280 --> 00:39:53.560
Newton's gravitation will predict it would

1051
00:39:53.560 --> 00:39:56.520
work. That effectively led to the precession

1052
00:39:56.520 --> 00:39:58.600
of Mercury's orbit, the wobble of the orbit

1053
00:39:59.090 --> 00:40:00.880
wobbling at a slightly different rate. And

1054
00:40:00.880 --> 00:40:02.410
uh, nobody could explain that. It led to

1055
00:40:02.410 --> 00:40:04.050
people speculating that maybe there's an

1056
00:40:04.050 --> 00:40:06.370
unseen planet closer to the sun than Mercury.

1057
00:40:06.690 --> 00:40:09.130
Because we'd seen for the planet Uranus that

1058
00:40:09.130 --> 00:40:10.730
an unseen planet pulling it around could

1059
00:40:10.730 --> 00:40:12.890
change its orbit. And that was Neptune. But

1060
00:40:12.890 --> 00:40:14.610
that didn't work. We never found anything.

1061
00:40:14.610 --> 00:40:17.170
And it wasn't until Einstein came up with the

1062
00:40:17.170 --> 00:40:20.010
general theory of relativity that, as a

1063
00:40:20.010 --> 00:40:22.370
byproduct of that, his method for

1064
00:40:22.530 --> 00:40:25.040
understanding how gravity works accurately

1065
00:40:25.040 --> 00:40:26.920
Models the precession of Mercury's orbit With

1066
00:40:26.920 --> 00:40:29.640
incredible precision. So when Newton came up

1067
00:40:29.640 --> 00:40:32.480
with his ideas, the predictions you

1068
00:40:32.480 --> 00:40:35.080
would make with Newton's gravity Were so

1069
00:40:35.080 --> 00:40:37.760
accurate that it was only 150 years or so

1070
00:40:37.760 --> 00:40:39.760
before our observations got good enough to

1071
00:40:39.760 --> 00:40:41.760
show that Newton's theories were wrong. They

1072
00:40:41.760 --> 00:40:44.200
disproved those theories, but we still use

1073
00:40:44.200 --> 00:40:46.560
them because they are so accurate. They're

1074
00:40:46.560 --> 00:40:48.640
slightly off, but they're so accurate and

1075
00:40:48.640 --> 00:40:50.720
easy to use that they're easier for me to use

1076
00:40:50.720 --> 00:40:53.690
in my modeling than general relativity, when

1077
00:40:53.690 --> 00:40:55.730
the uncertainties in the things I model are

1078
00:40:55.730 --> 00:40:57.250
so great that the difference between those

1079
00:40:57.250 --> 00:40:59.370
two is lost in the noise. So it's just easier

1080
00:40:59.370 --> 00:41:01.650
for me to use Newton's laws. But it's a

1081
00:41:01.650 --> 00:41:03.930
really good example of how theory makes

1082
00:41:03.930 --> 00:41:05.850
predictions that are verified for a very long

1083
00:41:05.850 --> 00:41:08.050
time. But eventually you get to the point

1084
00:41:08.050 --> 00:41:10.930
where you go beyond what theory explains,

1085
00:41:11.010 --> 00:41:13.370
and that leads to new theories. And in this

1086
00:41:13.370 --> 00:41:14.890
case, it's a case where there are these set

1087
00:41:14.890 --> 00:41:17.250
of theories that, uh, are very much at the

1088
00:41:17.250 --> 00:41:19.490
cutting edge of science, where the

1089
00:41:19.490 --> 00:41:21.650
predictions that they make are predictions of

1090
00:41:21.650 --> 00:41:24.130
things we have not yet seen. Because it's

1091
00:41:24.130 --> 00:41:25.730
fairly pointless to only predict the things

1092
00:41:25.730 --> 00:41:27.810
we have seen and not go beyond that. So they

1093
00:41:27.810 --> 00:41:30.530
predict things we haven't yet seen. One of

1094
00:41:30.530 --> 00:41:32.810
those things is the existence of cosmogenic

1095
00:41:32.810 --> 00:41:35.410
neutrinos. And, um, it may well be that this

1096
00:41:35.410 --> 00:41:37.250
is the first detection of a cosmogenic

1097
00:41:37.250 --> 00:41:39.930
neutrino, which then adds credence to the

1098
00:41:39.930 --> 00:41:42.010
idea that these quantum field theories work

1099
00:41:42.010 --> 00:41:44.130
and make sense. So it's that interplay

1100
00:41:44.130 --> 00:41:46.610
between theory and observation, an experiment

1101
00:41:46.610 --> 00:41:49.150
that I think is really interesting, Even if,

1102
00:41:49.150 --> 00:41:51.070
to be honest, I really don't understand it.

1103
00:41:51.470 --> 00:41:54.270
Andrew Dunkley: And what, uh, Jonti is saying, Casey, is that

1104
00:41:54.270 --> 00:41:56.750
it'll be 150 years before someone comes up

1105
00:41:56.750 --> 00:41:59.550
with a model that actually explains it.

1106
00:42:00.030 --> 00:42:01.950
Possibly it could happen that way. You never

1107
00:42:01.950 --> 00:42:04.790
know. Uh, and thanks for the question. Casey

1108
00:42:04.790 --> 00:42:07.590
and I assumed female, but, um, looking at the

1109
00:42:07.590 --> 00:42:10.390
spelling of Casey could be male. Apologies if

1110
00:42:10.390 --> 00:42:11.710
I got that the wrong way around.

1111
00:42:14.440 --> 00:42:17.240
Jonti Horner: Roger, your lots are here. Also space nuts.

1112
00:42:17.400 --> 00:42:20.320
Andrew Dunkley: Our final question today comes from young

1113
00:42:20.320 --> 00:42:21.000
Henrik.

1114
00:42:21.400 --> 00:42:24.360
Jonti Horner: Hello, It's Henrique from Portugal again.

1115
00:42:25.560 --> 00:42:28.440
This time I'd like to ask about the

1116
00:42:28.440 --> 00:42:30.340
object NWC, uh,

1117
00:42:31.240 --> 00:42:34.200
349A. What makes it so

1118
00:42:34.200 --> 00:42:36.360
extreme? How does it emit

1119
00:42:36.600 --> 00:42:39.480
lasers and lasers. Can you

1120
00:42:39.480 --> 00:42:42.090
explain to my dad what's masers are?

1121
00:42:42.330 --> 00:42:43.450
Thank you. Bye.

1122
00:42:44.010 --> 00:42:45.850
Andrew Dunkley: Thank you. Henrik. Uh, yes,

1123
00:42:45.850 --> 00:42:48.850
MWC349A.A for Apple

1124
00:42:48.850 --> 00:42:51.130
M, not eight. That's what I thought he said.

1125
00:42:51.130 --> 00:42:53.770
But um, yeah, this is ah, this is a,

1126
00:42:54.890 --> 00:42:57.730
a mysterious emission line star and

1127
00:42:57.730 --> 00:42:59.930
radio bright object in the constellation of

1128
00:42:59.930 --> 00:43:00.570
Cygnus.

1129
00:43:00.810 --> 00:43:01.370
Jonti Horner: Yes.

1130
00:43:01.690 --> 00:43:04.570
Andrew Dunkley: And it's um, it's, it's suffered an intensive

1131
00:43:05.370 --> 00:43:06.330
mass loss.

1132
00:43:06.970 --> 00:43:09.850
Jonti Horner: Yeah, it's a really interesting object. Now I

1133
00:43:09.930 --> 00:43:11.770
wasn't familiar with this object before the

1134
00:43:11.770 --> 00:43:13.490
question came in and it's probably something

1135
00:43:13.490 --> 00:43:15.970
that when I was Henrik's age, I'd have heard

1136
00:43:15.970 --> 00:43:17.930
of and come across and would have really

1137
00:43:17.930 --> 00:43:19.610
found fascinating, just like Henrik does.

1138
00:43:19.610 --> 00:43:22.370
It's fabulous question as best we

1139
00:43:22.370 --> 00:43:24.210
understand that this is something that is a

1140
00:43:24.210 --> 00:43:26.730
very luminous, very bright star,

1141
00:43:27.690 --> 00:43:30.250
much younger than the Sun. It's probably at

1142
00:43:30.250 --> 00:43:32.250
most 5 million years old. But it could either

1143
00:43:32.250 --> 00:43:34.800
be a baby star that's still forming

1144
00:43:34.960 --> 00:43:36.960
or a very massive star that's just coming to

1145
00:43:36.960 --> 00:43:38.640
the end of its life, even though it's only 5

1146
00:43:38.640 --> 00:43:40.120
million years old. And there's been a lot of

1147
00:43:40.120 --> 00:43:42.880
debate of that over the years. It

1148
00:43:42.880 --> 00:43:45.480
is famous and it's prominent because it's one

1149
00:43:45.480 --> 00:43:48.120
of the most bright things in the sky at uh,

1150
00:43:48.120 --> 00:43:50.880
millimeter and radio wavelengths. It's very,

1151
00:43:50.880 --> 00:43:52.680
very bright, very obviously visible, even

1152
00:43:52.680 --> 00:43:54.640
though it's way too faint to see with the

1153
00:43:54.640 --> 00:43:57.360
naked eye. Part of the reason it's too faint

1154
00:43:57.360 --> 00:43:58.760
to see with the naked eye though, is that

1155
00:43:58.760 --> 00:44:00.640
there's a lot of dust and gas around both

1156
00:44:01.060 --> 00:44:03.380
where the object is. We found that it's got a

1157
00:44:04.100 --> 00:44:06.380
disk of dust and gas around it. Let's edge

1158
00:44:06.380 --> 00:44:08.100
onto us and is blocking some of the light.

1159
00:44:08.420 --> 00:44:10.420
Plus it's in the spiral arm of the Milky Way,

1160
00:44:10.420 --> 00:44:12.420
so there's a lot of dust and gas between us.

1161
00:44:12.740 --> 00:44:14.540
So this thing has an apparent magnitude of

1162
00:44:14.540 --> 00:44:17.099
about 13, but there are about 10

1163
00:44:17.099 --> 00:44:19.140
magnitudes of extinction along the line of

1164
00:44:19.140 --> 00:44:21.020
sight between us and it, which means that for

1165
00:44:21.020 --> 00:44:23.620
every 10,000 photons it emits, only one

1166
00:44:23.620 --> 00:44:25.900
reaches us. In other words, if you could

1167
00:44:25.900 --> 00:44:28.040
clear all the dust and gas out, this will be

1168
00:44:28.040 --> 00:44:29.960
a third magnitude star and easy to see with a

1169
00:44:29.960 --> 00:44:30.640
naked eye.

1170
00:44:30.640 --> 00:44:31.000
Andrew Dunkley: Right.

1171
00:44:31.000 --> 00:44:33.160
Jonti Horner: So that's intrinsically how luminous it is.

1172
00:44:33.160 --> 00:44:35.960
It's thought to be about 1300 parsecs away.

1173
00:44:35.960 --> 00:44:38.920
So that's 39004000 light years. So

1174
00:44:38.920 --> 00:44:41.120
the light we receive from it we're seeing it

1175
00:44:41.120 --> 00:44:43.040
how it was 4,000 years ago when that light

1176
00:44:43.040 --> 00:44:45.920
was emitted. And because it's so

1177
00:44:45.920 --> 00:44:48.640
luminous in radio wavelengths, it's been

1178
00:44:48.640 --> 00:44:51.120
fairly well studied. And in particular, it

1179
00:44:51.120 --> 00:44:53.600
gives off a lot of energy at, uh, wavelengths

1180
00:44:53.600 --> 00:44:56.220
linked to molecular hydrogen. And it's known

1181
00:44:56.220 --> 00:44:59.100
as one of the few hydrogen masers that we see

1182
00:44:59.100 --> 00:45:01.260
in the sky. Which leads to Henrik's question

1183
00:45:01.260 --> 00:45:04.060
about what is a maser? The very

1184
00:45:04.060 --> 00:45:05.980
simple answer to that, which doesn't tell you

1185
00:45:05.980 --> 00:45:08.980
anything, is that a maser is a laser,

1186
00:45:08.980 --> 00:45:10.940
but happening at millimeter wavelengths. So

1187
00:45:10.940 --> 00:45:13.940
in the infrared, on radio. But it's the

1188
00:45:13.940 --> 00:45:15.940
same physical process. And in fact, masers

1189
00:45:15.940 --> 00:45:17.980
were what we developed before we could do

1190
00:45:17.980 --> 00:45:20.060
lasers, because lasers are the same

1191
00:45:20.060 --> 00:45:22.020
phenomenon happening at visible wavelengths

1192
00:45:22.020 --> 00:45:24.780
in the optical. That is a very accurate

1193
00:45:24.780 --> 00:45:26.260
description that tells you actually nothing

1194
00:45:26.260 --> 00:45:28.380
about what's going on. And I dug into this a

1195
00:45:28.380 --> 00:45:30.740
bit because like a lot of people, I use

1196
00:45:30.740 --> 00:45:32.780
lasers and think about them, but never really

1197
00:45:33.020 --> 00:45:35.820
remind myself how they work. Laser

1198
00:45:35.820 --> 00:45:38.620
stands for light activated.

1199
00:45:39.810 --> 00:45:42.140
Um, Simulated Emission of radiation.

1200
00:45:42.540 --> 00:45:44.740
Sorry, Light Amplification by Simulated

1201
00:45:44.740 --> 00:45:46.740
Emission of radiation. It's an acronym. And

1202
00:45:46.740 --> 00:45:49.420
MESA stands for Microwave Amplification by

1203
00:45:49.620 --> 00:45:51.860
Stimulated Emission of Radiation. So it's the

1204
00:45:51.860 --> 00:45:53.500
same process just happening at longer

1205
00:45:53.500 --> 00:45:56.500
wavelengths. What's happening effectively is

1206
00:45:56.500 --> 00:45:58.980
that when atoms are

1207
00:45:59.140 --> 00:46:01.860
excited, when energy is pumped into atoms

1208
00:46:02.100 --> 00:46:04.540
and that energy is absorbed by them, it makes

1209
00:46:04.540 --> 00:46:06.620
the electrons in those atoms jump from one

1210
00:46:06.620 --> 00:46:09.300
level to a higher energy level. And they are

1211
00:46:09.300 --> 00:46:12.180
very specific jumps in energy. It can only

1212
00:46:12.180 --> 00:46:14.220
jump by a certain amount. It can't miss a

1213
00:46:14.220 --> 00:46:16.770
gap. It's got to get exactly the right jump

1214
00:46:16.770 --> 00:46:19.570
to jump from one level to the next. So those

1215
00:46:19.570 --> 00:46:21.650
energy levels have very specific wavelengths

1216
00:46:21.650 --> 00:46:22.810
and we actually calculate them at

1217
00:46:22.810 --> 00:46:24.650
universities, part of our undergrad quantum

1218
00:46:24.650 --> 00:46:26.610
mechanics courses and things like this. It's

1219
00:46:26.610 --> 00:46:28.050
one of the tasks you have is work out the

1220
00:46:28.050 --> 00:46:30.530
energy levels of a hydrogen atom and

1221
00:46:30.930 --> 00:46:33.370
they are quantized such that, uh, when you're

1222
00:46:33.370 --> 00:46:35.130
at an energy level, if you want to jump down

1223
00:46:35.130 --> 00:46:36.730
to another one, you can only do that by

1224
00:46:36.730 --> 00:46:39.370
emitting a single photon. You can't emit

1225
00:46:39.370 --> 00:46:41.210
multiple photons that add up to that level.

1226
00:46:41.210 --> 00:46:43.850
You can only emit one photon. And you have to

1227
00:46:43.850 --> 00:46:46.850
hit the right energy level to get the gap.

1228
00:46:47.090 --> 00:46:49.850
And so that's why excited hydrogen glows at

1229
00:46:49.850 --> 00:46:52.730
very specific colors. So the photo behind me,

1230
00:46:52.730 --> 00:46:54.210
which won't be visible if you're listening to

1231
00:46:54.210 --> 00:46:56.050
this as a podcast, but the photo behind me

1232
00:46:56.050 --> 00:46:58.929
shows the Helix Nebula, which is a star

1233
00:46:58.929 --> 00:47:01.460
forming, sorry, the Trifid Nebula, which, uh,

1234
00:47:01.690 --> 00:47:03.290
is a star forming region in the middle of

1235
00:47:03.290 --> 00:47:05.930
It's a very distinctive pink color. And that

1236
00:47:05.930 --> 00:47:08.460
pink color is hydrogen alpha emission, which,

1237
00:47:08.530 --> 00:47:10.570
which is hydrogen atoms jumping from the

1238
00:47:10.570 --> 00:47:13.050
third energy level to the second, emitting

1239
00:47:13.050 --> 00:47:15.130
light, and all emitting light of exactly the

1240
00:47:15.130 --> 00:47:17.610
same color. So that's known as

1241
00:47:17.610 --> 00:47:20.450
spontaneous emission. That's where the atom

1242
00:47:20.450 --> 00:47:22.290
sheds its energy by emitting light of a

1243
00:47:22.290 --> 00:47:25.250
certain color. Simulated emission is where

1244
00:47:25.250 --> 00:47:27.570
something happens to trigger that emission,

1245
00:47:28.450 --> 00:47:30.930
specifically at a specific time. So you've

1246
00:47:30.930 --> 00:47:33.650
got an atom, um, that is excited, is sat at a

1247
00:47:33.650 --> 00:47:35.750
higher energy level, and something gives it a

1248
00:47:35.750 --> 00:47:38.430
nudge and causes it to emit energy. And the

1249
00:47:38.430 --> 00:47:40.430
way that that works is that it absorbs a

1250
00:47:40.430 --> 00:47:42.950
photon of the same energy of the energy level

1251
00:47:42.950 --> 00:47:45.190
difference that it was going to emit anyway,

1252
00:47:45.270 --> 00:47:47.390
and then immediately emits two photons of

1253
00:47:47.390 --> 00:47:49.830
that energy. So you get one photon in and two

1254
00:47:49.830 --> 00:47:52.670
photons out. Two photons out can hit two

1255
00:47:52.670 --> 00:47:54.790
atoms and trigger them to emit, which means

1256
00:47:54.790 --> 00:47:56.510
you get four photons out and so on. So you

1257
00:47:56.510 --> 00:47:59.350
can get this cascade. So what makes it work

1258
00:47:59.350 --> 00:48:01.630
is that there are many ways of exciting the

1259
00:48:01.630 --> 00:48:03.470
atoms in the first place. They don't have to

1260
00:48:03.470 --> 00:48:05.870
just absorb photons. They can be excited

1261
00:48:05.870 --> 00:48:07.690
through magnet magnetic fields, uh, or all

1262
00:48:07.690 --> 00:48:10.090
sorts of different things going on. And so a

1263
00:48:10.090 --> 00:48:12.930
maser is effectively somewhere where

1264
00:48:13.090 --> 00:48:15.890
emission is being stimulated by

1265
00:48:15.890 --> 00:48:18.490
incoming photons of a given wavelength, which

1266
00:48:18.490 --> 00:48:20.890
results in more photons being emitted of that

1267
00:48:20.890 --> 00:48:23.210
wavelength than are coming in. And so you get

1268
00:48:23.210 --> 00:48:26.010
this amplification effect. So in this

1269
00:48:26.010 --> 00:48:27.970
case, this being a hydrogen maser means that

1270
00:48:27.970 --> 00:48:30.410
you've got a lot of hydrogen gas there. That

1271
00:48:30.410 --> 00:48:32.890
hydrogen gas is being irradiated by emission

1272
00:48:32.890 --> 00:48:34.850
of a specific wavelength by this object.

1273
00:48:35.910 --> 00:48:37.800
Um, and that is stimulating the emission of

1274
00:48:37.800 --> 00:48:39.400
more photons, which means you get an

1275
00:48:39.400 --> 00:48:41.680
extremely bright emission at that wavelength

1276
00:48:41.840 --> 00:48:43.560
because you're getting this amplification

1277
00:48:43.560 --> 00:48:46.080
effect. And so that's how these things works

1278
00:48:46.160 --> 00:48:48.440
as a maser. And that has been very useful in

1279
00:48:48.440 --> 00:48:50.320
allowing us to study it because it means we

1280
00:48:50.320 --> 00:48:52.680
get a stronger signal, we get more light, so

1281
00:48:52.680 --> 00:48:53.680
there's more we can study.

1282
00:48:54.800 --> 00:48:57.680
What my research around it this morning

1283
00:48:57.840 --> 00:48:59.760
kind of found out was that there is some

1284
00:49:00.080 --> 00:49:02.650
significant debate historically over whether

1285
00:49:02.650 --> 00:49:05.450
this is firstly a binary star, or on its own,

1286
00:49:05.450 --> 00:49:07.610
there's another very hot blue star very close

1287
00:49:07.610 --> 00:49:10.050
to it in the sky that for a long time was

1288
00:49:10.050 --> 00:49:12.410
thought to be a binary companion. And that's

1289
00:49:12.410 --> 00:49:15.410
why this is MWC349A,

1290
00:49:15.410 --> 00:49:18.170
because there's a star MWC349B.

1291
00:49:18.970 --> 00:49:21.010
Now, recent studies that have measured the

1292
00:49:21.010 --> 00:49:23.490
radial velocity of the two stars suggests

1293
00:49:23.490 --> 00:49:26.330
that the star B is moving 35

1294
00:49:26.330 --> 00:49:29.310
kilometers per second compared to star A. So

1295
00:49:29.310 --> 00:49:30.750
they're not gravitationally held together

1296
00:49:30.750 --> 00:49:32.950
anymore. So they're probably not now a

1297
00:49:32.950 --> 00:49:35.550
binary. Though there is some debate whether

1298
00:49:36.190 --> 00:49:38.590
they were in the past, whether they were held

1299
00:49:38.590 --> 00:49:40.590
together by gravity. And then those two stars

1300
00:49:40.590 --> 00:49:42.990
have shed mass. As we said, this star seems

1301
00:49:42.990 --> 00:49:45.590
to have thrown mass away in recent times, may

1302
00:49:45.590 --> 00:49:47.270
even have lost half its mass. It may have

1303
00:49:47.270 --> 00:49:49.990
gone from 40 solar masses to 20. That

1304
00:49:49.990 --> 00:49:51.550
weakens its gravitational pull until

1305
00:49:51.550 --> 00:49:54.070
eventually the binary falls apart. So that's

1306
00:49:54.070 --> 00:49:55.550
one part of the debate. But the recent

1307
00:49:55.550 --> 00:49:58.120
results seem to suggest that even if they

1308
00:49:58.120 --> 00:49:59.960
were a binary in the past, they no longer

1309
00:49:59.960 --> 00:50:02.480
are. The other debate is

1310
00:50:02.960 --> 00:50:04.960
whether this is a very young star that's only

1311
00:50:04.960 --> 00:50:07.680
just forming now. Or whether it's a star that

1312
00:50:07.680 --> 00:50:09.320
formed a few million years ago and is coming

1313
00:50:09.320 --> 00:50:11.760
to the end of its life. And, um, you'd have

1314
00:50:11.760 --> 00:50:13.840
thought that was obvious. But for stars like

1315
00:50:13.840 --> 00:50:15.240
this, it's quite hard to tell, especially

1316
00:50:15.240 --> 00:50:17.280
when they're so obscured by gas and dust.

1317
00:50:17.760 --> 00:50:20.720
Now, if it was a baby star, the really

1318
00:50:20.960 --> 00:50:22.920
odd part of that would be, why are there no

1319
00:50:22.920 --> 00:50:25.330
other baby stars around it? Stars kind of

1320
00:50:25.330 --> 00:50:27.170
form in big nurseries. And particularly

1321
00:50:27.170 --> 00:50:29.690
massive stars don't tend to form alone. They

1322
00:50:29.690 --> 00:50:32.450
tend to form in big associations where lots

1323
00:50:32.450 --> 00:50:34.210
of stars are forming at once. And there's one

1324
00:50:34.610 --> 00:50:37.250
relatively near this called Cygnus OB2.

1325
00:50:37.650 --> 00:50:39.490
And, uh, one of the suggestions for this

1326
00:50:39.490 --> 00:50:41.410
star, if it's an older star that's coming to

1327
00:50:41.410 --> 00:50:43.530
the end of its life, is that it formed in

1328
00:50:43.530 --> 00:50:45.290
that association and was ejected in an

1329
00:50:45.290 --> 00:50:46.890
encounter with other stars and flung

1330
00:50:46.890 --> 00:50:48.730
outwards. And, um, we're seeing it quite far

1331
00:50:48.730 --> 00:50:50.370
away because it's traveled that distance

1332
00:50:50.370 --> 00:50:52.590
through its lifetime. So it formed there, but

1333
00:50:52.590 --> 00:50:55.550
it's escaped. If it's a baby

1334
00:50:55.550 --> 00:50:57.590
star, we have the problem of how is it only

1335
00:50:57.590 --> 00:50:59.270
just forming in an area where there's not

1336
00:50:59.270 --> 00:51:01.110
really any other stars forming around it.

1337
00:51:01.670 --> 00:51:03.990
Recent studies have suggested, by looking

1338
00:51:04.470 --> 00:51:07.270
over all things, the balance between carbon

1339
00:51:07.349 --> 00:51:09.950
13 and carbon 12, these two different carbon

1340
00:51:09.950 --> 00:51:12.870
isotopes in the gas that has been shed by

1341
00:51:12.870 --> 00:51:15.870
this star. Recent, uh, measurements of that

1342
00:51:15.870 --> 00:51:17.510
have suggested it's actually an old star.

1343
00:51:18.400 --> 00:51:20.840
Well, old for its mass, you know, about 5

1344
00:51:20.840 --> 00:51:22.360
million years old. But coming to the end of

1345
00:51:22.360 --> 00:51:25.160
its life, that has been shedding mass. And,

1346
00:51:25.160 --> 00:51:27.120
um, that is explained by the balance of the

1347
00:51:27.120 --> 00:51:29.280
isotopes in the gases that it has emitted.

1348
00:51:29.600 --> 00:51:31.680
Which fits in a bit better with the idea that

1349
00:51:31.680 --> 00:51:33.560
it may have formed in that Cygnus LB2

1350
00:51:33.560 --> 00:51:35.880
association a few million years ago, have

1351
00:51:35.880 --> 00:51:38.520
been flung outwards and escaped. Would also

1352
00:51:38.520 --> 00:51:40.740
fit A little bit with the idea that the star,

1353
00:51:40.740 --> 00:51:43.520
uh, B next to it, was once held to it as a

1354
00:51:43.520 --> 00:51:45.000
binary. But with the mass loss, they've

1355
00:51:45.000 --> 00:51:46.820
separated and they're going their separate

1356
00:51:46.820 --> 00:51:49.020
ways. You know, that happens all the time.

1357
00:51:49.500 --> 00:51:51.660
And so that all kind of, as a narrative seems

1358
00:51:51.660 --> 00:51:53.300
to fit together. But it's got a disk of

1359
00:51:53.300 --> 00:51:55.180
material around it that's nearly edge on.

1360
00:51:55.420 --> 00:51:57.700
It's got jets of material coming out of it.

1361
00:51:57.700 --> 00:51:59.900
There is a suggestion that it's probably shed

1362
00:52:00.300 --> 00:52:02.300
something like 20 times the mass of the sun

1363
00:52:02.300 --> 00:52:03.980
over the last few hundred thousand years.

1364
00:52:04.540 --> 00:52:06.460
And, uh, that it's shedding something like

1365
00:52:06.940 --> 00:52:09.660
1/100,000th of a solar mass per year,

1366
00:52:10.380 --> 00:52:12.580
which doesn't sound like a lot, but that's a

1367
00:52:12.580 --> 00:52:14.340
huge amount of mass to be throwing away in

1368
00:52:14.340 --> 00:52:16.460
every given year, which means it would throw

1369
00:52:16.460 --> 00:52:18.600
away a mass equ, the mass of the sun in just

1370
00:52:18.600 --> 00:52:21.560
100,000 years. That's really significant

1371
00:52:21.800 --> 00:52:23.720
mass loss going on as this star comes to the

1372
00:52:23.720 --> 00:52:25.840
end of its life. And it's a really

1373
00:52:25.840 --> 00:52:28.400
interesting case study of that detective

1374
00:52:28.400 --> 00:52:31.320
story again, of how we gather clues from

1375
00:52:31.320 --> 00:52:33.000
all these different types of observations

1376
00:52:33.880 --> 00:52:36.040
about a star that for us, at optical

1377
00:52:36.040 --> 00:52:38.280
wavelengths is so heavily concealed from us

1378
00:52:38.600 --> 00:52:41.120
that only one part in 10,000 of the light it

1379
00:52:41.120 --> 00:52:43.160
emits actually reaches as the rest of it gets

1380
00:52:43.160 --> 00:52:45.600
absorbed en route. Um, and that's why it's

1381
00:52:45.600 --> 00:52:47.400
been such a challenging problem for astronomy

1382
00:52:47.400 --> 00:52:49.240
for so many years, because it's really hard

1383
00:52:49.240 --> 00:52:52.080
to see what's going on. But by looking at the

1384
00:52:52.080 --> 00:52:54.600
masers emitting this light, by looking at all

1385
00:52:54.600 --> 00:52:56.360
the different things going on around it, by

1386
00:52:56.360 --> 00:52:59.080
doing clever studies of the chemistry of the

1387
00:52:59.080 --> 00:53:01.560
gases around it, we can start to piece

1388
00:53:01.560 --> 00:53:03.080
together its life story and figure out what

1389
00:53:03.080 --> 00:53:05.720
it is. I don't think that story of

1390
00:53:05.720 --> 00:53:08.520
discovery is finished yet, by any means. And

1391
00:53:08.520 --> 00:53:09.840
it may well be, Henrik, that when you're

1392
00:53:09.840 --> 00:53:11.400
older, you can actually work on this object

1393
00:53:11.400 --> 00:53:13.240
and learn more about it yourself. I suspect

1394
00:53:13.240 --> 00:53:15.560
people will still be discovering things about

1395
00:53:15.560 --> 00:53:18.400
this object in decades to come. But

1396
00:53:18.400 --> 00:53:20.640
it's a really fascinating object, and I'm

1397
00:53:20.640 --> 00:53:22.080
just so delighted that you brought it to my

1398
00:53:22.080 --> 00:53:23.440
attention because I'd never stumbled across

1399
00:53:23.440 --> 00:53:25.080
it before, and it's really, really cool.

1400
00:53:25.240 --> 00:53:27.760
Andrew Dunkley: Yes, it's, um. Sorry for this. It's

1401
00:53:27.760 --> 00:53:30.480
amazing. Uh, but, Henrik, thanks for the

1402
00:53:30.480 --> 00:53:33.040
question, and you do sound, uh, very astute,

1403
00:53:33.040 --> 00:53:35.000
and maybe, maybe you will be the one that

1404
00:53:35.000 --> 00:53:37.360
will solve it in years to come. Lovely to

1405
00:53:37.360 --> 00:53:40.280
hear from you. And if you have questions for

1406
00:53:40.280 --> 00:53:43.010
us, please send them through. We can take,

1407
00:53:43.010 --> 00:53:44.950
uh, your questions on our website. So, Space

1408
00:53:44.950 --> 00:53:47.910
Nuts podcast.com spacenuts IO

1409
00:53:48.230 --> 00:53:51.110
click on that little AMA link up the top

1410
00:53:51.110 --> 00:53:53.630
and you can send us text or audio

1411
00:53:53.630 --> 00:53:55.470
questions or both. Some people have done

1412
00:53:55.470 --> 00:53:57.870
that. And don't forget to tell us who you are

1413
00:53:57.870 --> 00:53:59.830
and where you're from. And, uh, yeah, we're

1414
00:53:59.830 --> 00:54:02.150
kind of running sort of

1415
00:54:02.310 --> 00:54:05.310
parallel with the number of questions we need

1416
00:54:05.310 --> 00:54:07.230
each week. So, uh, we haven't got a big

1417
00:54:07.230 --> 00:54:09.310
stockpile at the moment. So it's a good time

1418
00:54:09.310 --> 00:54:12.230
to send some questions into us. So please do.

1419
00:54:12.230 --> 00:54:14.670
Would love to hear from you. Don't even worry

1420
00:54:14.670 --> 00:54:17.310
if you think it's dumb, because there's no

1421
00:54:17.310 --> 00:54:19.390
dumb questions in astronomy and space

1422
00:54:19.390 --> 00:54:21.950
science. There's weird questions, but there

1423
00:54:21.950 --> 00:54:24.510
aren't any dumb questions. And, uh, while

1424
00:54:24.510 --> 00:54:25.990
you're on our website, have a look around.

1425
00:54:26.070 --> 00:54:28.630
There's a little link, uh, shop

1426
00:54:28.630 --> 00:54:30.670
link. It's really good. You can get some

1427
00:54:30.670 --> 00:54:33.630
Space Nuts memorabilia there or sign

1428
00:54:33.630 --> 00:54:36.580
up to our Astronomy Daily Newsfeed. And if,

1429
00:54:36.580 --> 00:54:38.710
uh, you are interested in becoming a patron,

1430
00:54:38.780 --> 00:54:41.750
uh, you can do that via the website as well

1431
00:54:41.750 --> 00:54:44.390
under the support. Support our podcast link.

1432
00:54:44.800 --> 00:54:46.990
Uh, those are just options. None of it's

1433
00:54:46.990 --> 00:54:49.470
mandatory. And, uh, we appreciate all the

1434
00:54:49.470 --> 00:54:52.230
support we get, so thank you. And Jonti,

1435
00:54:52.230 --> 00:54:54.430
thank you so much. Uh, it's been great to

1436
00:54:54.430 --> 00:54:56.230
talk to you and, uh, we'll see you on the

1437
00:54:56.230 --> 00:54:56.950
next episode.

1438
00:54:57.270 --> 00:54:58.630
Jonti Horner: Yeah. Thank you for having me. It's good to

1439
00:54:58.630 --> 00:54:59.110
be back.

1440
00:54:59.270 --> 00:55:01.470
Andrew Dunkley: Always a pleasure. Jonti, uh, Horner,

1441
00:55:01.470 --> 00:55:03.190
professor of Astrophysics at the University

1442
00:55:03.350 --> 00:55:05.950
of Southern Queensland. And, uh, uh, thanks

1443
00:55:05.950 --> 00:55:08.560
to Huw in the studio who, um,

1444
00:55:08.560 --> 00:55:11.190
couldn't be with us today because they're

1445
00:55:11.190 --> 00:55:13.550
going to hate me for this one. He got lost in

1446
00:55:13.550 --> 00:55:16.470
a maser. Oh, dear. And from me, Andrew

1447
00:55:16.470 --> 00:55:18.030
Dunkley. Thanks for your company. We'll see

1448
00:55:18.030 --> 00:55:20.070
you on the next episode of Space Nuts. Bye.

1449
00:55:20.070 --> 00:55:20.430
Bye.

1450
00:55:21.710 --> 00:55:23.910
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