Oct. 7, 2024

Navigating the Cosmos and Redshift Riddles

Navigating the Cosmos and Redshift Riddles

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Space Nuts #458 Q&A Edition
Join Andrew Dunkley and Professor Fred Watson in this engaging Q&A episode of Space Nuts, where...

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Space Nuts #458 Q&A Edition
Join Andrew Dunkley and Professor Fred Watson in this engaging Q&A episode of Space Nuts, where they tackle a variety of intriguing questions from listeners. From the mysteries of light and redshift to the enigmatic cores of gas giants, this episode is packed with fascinating insights and cosmic curiosities.
Episode Highlights:
- Light and Redshift: Mario from Melbourne (Australia) queries how light can redshift if it doesn't experience time. Fred Watson Watson delves into relativity and the observer's role in this cosmic phenomenon.
- Gas Giants' Cores: Nigel from Brisbane (Australia) wonders if there's a rocky planet beneath the gas layers of Jupiter and Saturn. Explore the theories about the mysterious cores of these colossal planets.
- Galaxy Collisions: Raul from California asks about the collision of galaxies amidst the universe's expansion. Discover why some galaxies are on a collision course despite the ever-expanding cosmos.
- Future Navigation: David from Tucson questions how we will navigate when exploring beyond our solar system. Learn about the quasars that provide a stable reference point for cosmic navigation.
For more Space Nuts, including our continually updating newsfeed and to listen to all our episodes, visit our website. Follow us on social media at SpaceNutsPod on facebook, X, YouTube Music, Instagram, and TikTok. We love engaging with our community, so be sure to drop us a message or comment on your favourite platform.
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Become a supporter of this podcast: https://www.spreaker.com/podcast/space-nuts/support.
Stay curious, keep looking up, and join us next time for more stellar insights and cosmic wonders. Until then, clear skies and happy stargazing.

 

 

WEBVTT

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Hi, there, Andrew Duncley again with another episode of Space Nuts,

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and it's good to have your company. This is a

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Q and A edition. This is where we answer your

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questions if we can. If we can't, we just pretend to.

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We've got questions about light and redshift. Today we're also

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going to talk gas giants, expansion of the galaxy versus

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or expansion of the universe versus galaxy collisions, and a

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future of navigation reference points. How are we going to

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do that? When we start going further and further out,

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those questions will be answered or they'll be faked. We're

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not sure yet. Deep fake radio coming up soon on

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this edition of Space Nuts fifteen seconds. Guidance is in

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channel ten nine ignition sequence Space Nuts or three two.

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One Space Nuts.

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As can I report it?

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Neils good and.

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He's here again, like a fly on a piece of meat.

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Hello Fred, Thanks so do Thanks professor Fred. What's an

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astronomer at large? Nice to see you.

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Yeah, that's right, it's nice to see you too. I

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think I.

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Have enough digs at Hugh. I thought maybe I.

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Should just should That's fine.

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Land a left hook for a change. It always comes

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back and hits me. Though eventually, so, yeah, I can't

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take it.

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I'm tough.

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Let's let's go straight to our questions. Our first question today,

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Fred comes from Mario in Melbourne. He likes to go

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go karting. Hi, Fred and Andrew, hoping you can help

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explain why if light itself doesn't experience time, how can

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it redshift? Doesn't red shifting imply it changes somehow, which

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implies it must have been subject to time. Or is

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this some sort of relativity witchcraft where we as observers

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experience time and the red shift, but the photon itself

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somehow in all states it can be simultaneously or something

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like that. Yeah, simultaneously or something like that. Appreciate you

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unscrambling my brain on this one. Still listening from the

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far start keep up the great show, Mario from Melbourne.

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I think we've kind of had variations of this question

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come up in the past. People sort of have trouble

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differentiating between light and time and what's going on out there.

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Can you shed some light on this one for it?

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I'm sorry, I'm completely in the dark about this one.

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It's a good point though, and so it's made me.

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You know, it's got the old cogs working to try

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and work out what's happening. Because that's right. Because light

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travels at the speed of light to the fastest speed

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anything could travel through the universe, it does not experience time.

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A photon of light does not experience time, and yet

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they change. And you're right, Mario is correct that we

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do see photons changing because the photons that we are

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now receiving from distant galaxy, for example, are highly red shifted.

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They've become ready photons. Now, what that corresponds to is

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a loss of energy, which results from the expansion of

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the universe. And so I think I'm right in saying

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that the photon doesn't notice that. It doesn't know that

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it's lost energy because it doesn't experience time. So I

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think you know, in a sense the loss of energy,

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which by the way, just filters out into the universe.

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Apparently normally that's where it goes. It's I think that

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is a property of the observer, the fact that we're

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observing this thing. The photon, the best of my understanding,

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doesn't care it arrives at the same time as it

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left because it doesn't experience time. But it might be

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surprised that where the place where it arrived at is

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very different from the place where it left out in

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terms of the energy balance and what's happening there. I'm

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not sure whether I'm making much sense here, Mario, but

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that's my understanding of the situation.

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Okay, it is a bit complicated. It'd be nice to

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be a photon if you're doing a long haul flight,

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because if you didn't experienced time, you wouldn't have to

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worry about it twenty hour flight to Turkey, for example,

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or anything like that. Yes, this is weak, yeah all over. Yeah,

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we hope we unscrambled your brain, Mario, because it is

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a bit of a scrambling issue. But photons don't experience time,

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and they don't know that they're losing energy. It's sort

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of like old people.

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Yep, yep, go to health. I probably you should say that,

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though you know. Now look I can vouch for that.

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I'm starting to.

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Experience that myself. Yes, thanks, Mario. Let's move on to

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our next one. This comes from Nugel.

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Oh friend Andrew, this is Nigel from Brisbane, Australia. I

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have two questions about our gas giants, Jupiter and Satin.

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I want to know beneath all that gas. Is there

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a rocky planet and if so, how big are they

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in relation to the Earth? Okay, thank you, love the show.

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Keep up the good work, thanks Nigel.

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Yeah, look, its.

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Theory, isn't it.

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Fred. We don't know for sure what's down deep in

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those gas giants, but there might be something.

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Well, you've absolutely answered the question, Andrew.

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Okay, we'll move on to the next one from Raoul.

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Nigel's question is you know it's one that many astronomers

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and plunge your scientists ask because we don't know, we

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don't know the answer. The modeling suggests that, because of

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the way we believe planets are formed, that there should

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be a rocky core underneath all that gas, that it

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should be quite massive, maybe with a fair degree of

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a water ice involved with it as well. Although some

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of the papers that I've read suggest that there might

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be something called metallic hydrogen at the center of these

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gas giants. I'm not sure what that means. Probably mean

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hydrogen in a state where it can conduct electricity. So yeah,

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so that's it's a question that's really at the forefront

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of knowledge. So you and me both, Nigel, I wonder

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what's at the center of these gas giants and how

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big the central core might be if there is one,

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which we assume there is.

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Yeah, I mean guess giants to a certain degree. What

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could have been stars had their formation happened in a bigger,

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better way. At what point do they reach in size

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or structure where they wouldn't have a solid core? Like

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would a brown dwarf? How does have a solid core?

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Perhaps, Yeah, that's certainly a brown dwarf would have a core,

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and it probably wouldn't be solid either, similar to more

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similar to what the Sun's core we think is like,

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compared with what a planet's core is like. So brown

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dwarf has nuclear reactions taking place, but they're low level.

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Once they're something called deuterium burning, and that doesn't generate

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anything like the same amount of heat as the hydrogen

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process that is going on at the center of our sun.

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So at the center of the Sun, you've got this

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ball of energy, very very hot, radiating gamma ray photons

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out which eventually find their way as a visible light

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out to the surface. The brown dwarf, you've got low

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level radiation which finds its way to the surface. With

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a gas giant, though we don't know that's the thing.

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We really don't know what the core would below.

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That.

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The thinking is that that they are cold enough to

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have a solid core. You know that you're not talking

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about a ball of energy. But we do know again

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that there are nuclear actions taking place. For example, in

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the core of Jupiter Jupiter radio is at one point

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eight times more heat than it receives from the salt

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that's coming from maybe uranium fission or something like that

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happening down there in its interior.

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Wow, do they have a theory if Jupiter has a core?

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Do they have a theory on how big it is

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compared worth?

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Probably? But look, I'm going to take as take a

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punt and say yes, people probably do think it is

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about the size of Earth. I'm sure that kind of

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suggestion before. I just remember Jupiter's about eleven times the

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diamature of Earth.

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Yeah. Wow, all right, jury is still out, Nigel, but

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it maybe could be done. Oh type of scenario. Thanks

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for the question. Sorry, nothing to do with us, nothing

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to see here. This is space Sandred Duntley with Fred Watson,

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Professor Astronomer at Large. Great guy, Now let's take a

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Three Space Nuts.

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Okay, our next question, Fred comes from Raoul.

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Hi, guys, Raoul from California here and a big Chelsea fan.

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I know you were talking about American football, but I

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do like europeanotball. Had a question for you. If the

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universe is ever expanding from the Big Bang, then all

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the galaxies will be moving apart from each other. But

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I recall seeing on a show that galaxies could one

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day collide. Does that mean that the universe is stopping

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its expansion or slowing its expansion, allowing the gravity of

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galaxies to then collide. And if that is the case,

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will the universe one day stop expanding and start to

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contract upon whatever the hugest big black hole in the

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middle of the universe really is. Thanks a lot, you

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guys do great love listening to it. Beat the show.

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I love what you did, right, Thank you, David Chelsea.

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Oh sorry, yeah, David, next roll roll thanks for that. Yes,

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Chelsea fan, but yeah, we'll forgive you for that. I'm

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a Liverpool fan myself. Do you follow English Premier League?

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Most League slightly? Yeah? Only you know some of the

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bigger teams. I've was interested in what they're doing. I've

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got a son in law and a grand couple of

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grandsons who are absolutely mad Manchester United freaks, and you know,

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various various other football teams. I never really got heavily

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into football. I can never remember which I was supposed

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to be kicking the balls and it wasn't nice team really,

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But yeah, that takes an interest.

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Yeah, I played soccer for ten years, never won a thing.

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I didn't even win the Raffle anyway. Raoul's asking about

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the universe and his expansion versus galaxy collisions basically, and

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is the expansion slowing or stopping? And is that why

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galaxies are going to crash into each other? Is it

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all going to sort of fall back into a giant

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black hole in the middle. We've had variations of questions

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like this over the years. It's one that always spawns

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a lot of interest.

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It does, doesn't it. And there are actually two things

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going on here. I think in rolls question because it's

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quite right that some galaxies do collide with each other,

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but in fact we are in poor position for a

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collision with Andromeda that might already be happening.

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In fact, yeah, in fact, yeah, we talked about it

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the other day. They're actually sort of you know, tickling

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their fingertips at the moment because of their giant gas balls.

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That's been revealed.

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Indeed. So and so why are they colliding if the

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universe is expanding? Because both those statements are true. The

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universe is expanding, and the two galaxies are colliding. And

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that's because at the on the scale of the distance

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between Us and Andromeda, which is two point five million

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light years, the expansion of the universe is negligible more

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or less the universe. The universe is expanding, but over

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a small distance like that, what becomes the dominant force

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is gravity, and the gravity, the gravitational pull between the

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Milky Way and Andromeda, easily enough to overcome the fact

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that they're being pulled apart much more gently by the

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expansion of the universe. So, and that's we give a term.

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We've got a name for the individual motions of galaxies

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kind of superimposed on the expansion of the universe. We

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call it their peculiar emotions. And it's so the peculiar

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motion of Milky Way relative to Andromeda. Is they colliding

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together and they will collide, whereas the expansion of the

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universe is trying to pull them apart, but at a

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much much slower rate, if I can put it that way.

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It's only when you look on the big scales that

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you see the real effects of the expansion of the universe,

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things that are billions of light years away from us

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rather than just a couple of million, And basically Raoul's right.

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Until nineteen ninety eight, we used to think that eventually

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the gravitational pull of everything in the universe would slow

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down the expansion and the universe would indeed collapse on

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itself in what we always call Andrew.

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The ganeb GiB, the gonab.

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GiB exactly, big bang, that's right, Brian branch mates praise

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the gonnab GiB. We used to think often called the

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big crunch as well. That was the thinking. But it

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was when Brian Schmitz Ant his colleagues and other colleagues

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in the United States, when they discovered the accelerated expansion

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of the universe that possible the possibility of the gadab

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GiB was thrown out of the window. Because the universe is,

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as far as we know, going to expand forever and

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there isn't enough stuff in it for its gravitational pull

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to halt the expansion. And part of that is because

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we think that space itself has an energy we call

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it dark energy, and the more space you have, the

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more energy you've got, and that energy is trying to

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push things apart, to push the universe into ever ever

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faster expansion. So, yes, it looks as though that big

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crunch scenario has gone out the window. But it was

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very popular in the nineteen seventies and eighties.

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So what's the opposite to a big crunch? It's a

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Hagner gibnurk.

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Yes, that sounds right.

291
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Yeah, someone's going to ask you again because we've had

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00:19:10.079 --> 00:19:10.920
the question before.

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But you know, if the.

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Universe keeps expanding and it's filling with dark energy, where

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where's the energy coming from? You know, wouldn't have that

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has that fueling itself? We don't know.

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We all comes out of space.

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00:19:25.319 --> 00:19:28.839
Yeah, it comes from somewhere. Yeah, people say I was

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coming from a dark matter, but when they're not related,

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they're just badly named.

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00:19:33.359 --> 00:19:37.119
Yes, that's correct. Maybe it's coming from outside.

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You know, if there's multiverses or that would be something,

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00:19:40.960 --> 00:19:44.400
wouldn't it. We should just go and have a look. Simple.

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That's a good idea, same voyage that.

305
00:19:48.680 --> 00:19:51.759
Well, it's on its way. We just have to sit

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00:19:51.799 --> 00:19:54.680
here and twiddle our thumbs and just wait a little while,

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and then we'll know if the batteries don't run out. Uh.

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Did we finish with Raoul? I think so yeah, Yes,

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all the best Raoul, and I hope Chelsea doesn't win

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as much as Liverpool. Let's go to our final question,

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00:20:11.519 --> 00:20:14.240
and this one comes from this is David. Wow, what

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00:20:14.319 --> 00:20:18.160
a coincidence. Hi love your podcast. I live in the

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00:20:18.200 --> 00:20:22.000
lovely dark city of Tucson. That will be the Arizona variety.

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I imagine my question my question. I assume astronomers use

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00:20:26.599 --> 00:20:30.200
the sun as a center of reference, but what about

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00:20:30.240 --> 00:20:34.319
the future when we want to travel somewhere else? Everything

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00:20:34.359 --> 00:20:39.680
is moving and it's a no body system. It's hard

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to know exactly where anything is going to be if

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00:20:43.240 --> 00:20:46.839
you wait long enough, How will you tell our colony

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00:20:46.960 --> 00:20:51.079
on proximate sentry where to go or where to look

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00:20:51.119 --> 00:20:53.599
when it takes four point two years for them to

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00:20:53.640 --> 00:20:57.319
get the message? That's from David. I like this question.

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It's a long term future problem when we're living in

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00:21:02.359 --> 00:21:06.640
other parts of the of the galaxy outside our own

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solar system. We've we've made the giant leap and ended

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up on one of those perfectly normal planets around the

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Alpha Centauri system, and we want to come back. How

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do we find how do we find our way back?

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00:21:23.480 --> 00:21:25.680
I mean, we can find our way there, so I

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assume we can find our way back. M Mathematics would

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00:21:32.200 --> 00:21:33.839
be my answer to this one.

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00:21:33.920 --> 00:21:37.720
Well, it is, it's it's a it's a good question actually,

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and it has a real significance to it because we

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we need we already need reference points like that for

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00:21:50.119 --> 00:22:00.000
things like GPS, you know, satellite navigation systems, space space navigator.

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00:22:01.119 --> 00:22:04.759
Even in the small distances within our solar system, you

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need fixed reference points. And what we use are the

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00:22:10.640 --> 00:22:14.799
things on the sky that move least and that bright,

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00:22:16.240 --> 00:22:20.440
and they are quasars. So quasars are very bright sources,

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00:22:20.839 --> 00:22:24.079
but there are very great distances, so distant that nothing

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00:22:24.519 --> 00:22:26.839
we could ever do in terms of our movement would

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change their positions on the sky. And so quasars have

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formed the fundamental reference system that's used in astronomy actually

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as well as for navigation. We use them to set

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00:22:39.200 --> 00:22:45.480
up basically reference systems for measuring galaxy position, star positions,

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00:22:45.599 --> 00:22:47.960
things of that sort. You use something that's not going

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to move, and the quasars don't move because they're so

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far away. So it's already there, David. And hopefully when

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you leave Tucson and head out towards Alpha Centauri, you

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won't need to have any worries that you'll lose your

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00:23:02.160 --> 00:23:04.279
way home. You'll find your way.

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00:23:04.279 --> 00:23:07.680
But yes, and don't ignore the sign that says next

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00:23:07.880 --> 00:23:12.480
fuel stop two bill in kilometers. You really don't want

354
00:23:12.519 --> 00:23:15.079
to skip that one because it's a long way to

355
00:23:15.119 --> 00:23:21.559
the toilet, let's face it. Yeah, yeah, all right, I

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00:23:21.559 --> 00:23:23.000
didn't realize it'd be that easy, Fay.

357
00:23:23.400 --> 00:23:25.519
It's good to know. Yep.

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00:23:26.079 --> 00:23:27.680
We just got to we've just got to perfect the

359
00:23:27.720 --> 00:23:30.599
engines that enable us to travel far distance is in

360
00:23:31.000 --> 00:23:33.680
a bit of a hurry. That's that's probably the bigger

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00:23:33.759 --> 00:23:38.599
challenge than the navigation. Thanks David. Great question, and if

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00:23:38.640 --> 00:23:40.920
you have a question please send it into us fire

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00:23:40.960 --> 00:23:44.119
our website space nuts dot io. You thought I was

364
00:23:44.160 --> 00:23:46.920
going to say space nuts podcast dot com, didn't you. Yes,

365
00:23:46.960 --> 00:23:49.319
well that counts to you can use both. They all

366
00:23:49.400 --> 00:23:52.319
end up in the same place, and you can send

367
00:23:52.359 --> 00:23:54.799
us a text or audio question just by clicking on

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00:23:54.839 --> 00:23:57.440
the AMA tab. And if you've got a device with

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00:23:57.559 --> 00:23:59.480
a microphone, you're all set down. Forget to tell us

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00:23:59.519 --> 00:24:01.359
who you are, where you're from, and don't forget to

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00:24:01.440 --> 00:24:04.200
leave your reviews on whatever platform you use to listen

372
00:24:04.240 --> 00:24:08.839
to us and social media, follow us, like us, subscribe

373
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wherever you are. We'd love you to make our little

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00:24:12.039 --> 00:24:14.000
family a little bit bigger. And don't forget about the

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00:24:14.000 --> 00:24:18.880
Space Nuts podcast group on Facebook. It's always growing. It's

376
00:24:18.920 --> 00:24:22.759
growing like a like a blob of gas in a

377
00:24:22.839 --> 00:24:27.880
nebula or whatever it is, and will Yeah. It's where

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00:24:27.920 --> 00:24:31.240
you can sort of chat with like minded people who

379
00:24:31.279 --> 00:24:34.799
follow Space Nuts, talk to each other, ask each other questions,

380
00:24:34.799 --> 00:24:39.839
share your astronomical photographs and stories. It's growing at a

381
00:24:39.920 --> 00:24:42.839
rate of knots. It is bread. And thank you for

382
00:24:42.920 --> 00:24:46.680
your company today, friend, Thanks for tolerating my stupidity and

383
00:24:46.720 --> 00:24:47.880
answering all those questions.

384
00:24:50.279 --> 00:24:55.680
That's all right, I can live with Andrew, No, we'll

385
00:24:55.680 --> 00:24:58.440
continue to do so, keep up the good work. It's

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00:24:58.480 --> 00:25:00.759
always great to talk. Thanks a lot, We'll see you soon.

387
00:25:00.839 --> 00:25:04.680
Professor Fred Watson, Astronomer at Large, and the Not Professor Hugh.

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00:25:05.359 --> 00:25:08.519
Thank you to him for helping out Not today and

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00:25:08.559 --> 00:25:12.519
we'll see you very soon. Andrew Dunkley signing off, We'll

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00:25:12.519 --> 00:25:15.640
catch you on the very next episode of Space Nuts.

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00:25:15.640 --> 00:25:20.160
Bye Byepacenuts. You'll be listening to the Space Nuts podcast

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00:25:21.799 --> 00:25:26.960
available at Apple Podcasts, Spotify, iHeart Radio, or your favorite

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podcast player. You can also stream on demand at bites

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dot com. This has been another quality podcast production from

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nights dot com.
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