Cosmic Q&A: Black Holes, Stellar Densities & the Sun's Sudden Disappearance

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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, our first one for the

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year. My name is Andrew Dunkley, your host.

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And we've got questions from Justin,

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who's got, um, a sent us an audio

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question. Um, he's talking about the space

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that contains the equivalent to 4 million

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stars in comparison to a black, ah, hole, I

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think. Can't remember. I don't write down

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enough when I write down the descriptions of

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questions. Uh, Charles,

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you're right. Fred's saying the same thing.

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Uh, Charles says, um, is asking us

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a question about the retraction of, uh, the

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universe, the shrinking of it. Uh, and,

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uh, Dean is asking, uh, about what might

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happen if the sun instantaneously

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disappeared. What would be the effect on our

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solar system and our planet specifically. And

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Patrick has some thoughts about, uh, both the

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voyages one and two, mainly

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the fact that the data we've put on the

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plaques that have been put on board the

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Voyages is actually telling anyone who

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finds them a lie. That's all coming up

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in this edition of Space Butts. And

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with us once again to decipher all of that

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gibberish that I just mentioned. And it's not

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the questions that are gibberish, it's my

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interpretation of them is Professor Fred

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Watson, astronomer at large. Hello, Fred.

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Professor Fred Watson: Hi, Andrew. Your interpretation was more or

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less the same as what I thought when I saw

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them. So I think we're on the same

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wavelength, which is good.

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Andrew Dunkley: Okay. Okay, well, that's good. Uh, we

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might as well just hit them straight on the

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head.

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And our first question is an audio question.

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And this one comes from Justin.

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Justin: G', day, Andrew and Fred. I'm Justin down in

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Melbourne. Like Fred, I'm an

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expat POM and my astronomical claim to

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fame is that I witnessed the total solar

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eclipse in Cornwall in the UK in

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1999. Two friends and

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I camped nearby and joined the crowds at

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Newquay beach on that day for a

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lifetime bucket list event.

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So I have a mathematical question. I've often

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heard it said that the black hole at the

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center of the Milky Way galaxy Sagittarius A

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is 4 million solar masses.

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So for comparison, what would the

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radius be in light years of a

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sphere centered on the Earth that contains

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the nearest 4 million stars?

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Thanks very much.

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Andrew Dunkley: Thank you, Justin. Cornwall. That's where my

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family originated before

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they, um, they got sent out here. Now, I

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think they came voluntarily. We, we didn't

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come with the convicts. We, we came out

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later. But, um, yeah, Justin, good question.

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Four million stars. Um, what sort of Space

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would that take up in terms of a radius in

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light years? I think was the guts of his

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question.

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Professor Fred Watson: Yes. So, uh, a little bit more

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subtle than that. It's, it's saying if

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you, if you're sitting here on planet Earth,

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um, what sort of,

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you know, in our locality, uh, in the

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um, Western spiral,

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the galaxy, it's the Orion spur, where we

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are, uh, that spiral arm that we sit

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in. Um, what's the, it's so it's really

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a question about the density of stars in our

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region. Uh, and that's something very well

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established because we know the distances of

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lots of stars. Uh, so I'm

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going to put it in much rounder figures. Uh,

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uh, but if you

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look at uh, out to

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a thousand light years, okay, so you've got a

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sphere of radius a thousand light years,

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then that's going to have something like 10

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million stars in it. Whoa. So that's more

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than what uh, what um, Justin's

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talking about. Uh, but the way this

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changes, uh, it changes non linearly.

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Uh, so I'm guessing, so I'm going to take a

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guess that you know, around 9, 900

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light years or thereabouts, you

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would probably have something like 4 million

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stars, which is the same uh,

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mass as the mass of the supermassive uh,

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black hole at, of the galaxy. So it's

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actually quite a long way, you know, you're

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looking out. Yeah, several hundred light

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years. Uh, uh, in terms of

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radius. Uh, and

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um, it's actually I think you would

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probably be able to find a tool online. I

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haven't found it myself because I haven't

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really looked for it, but I bet you can find

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a tool that gives you the exact answer to

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that. Uh, how many stars are within a radius

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of X number of light years. And if you

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put in a good guess of light years, you'll

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probably get the right number of stars.

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Andrew Dunkley: Do you want me to test it?

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Professor Fred Watson: Yeah, if you can find one.

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Andrew Dunkley: Yeah. I've got an idea. So what's the

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question? How many stars

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in uh, say within

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900 light years?

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Professor Fred Watson: Okay, see what it is. This is a

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guess on my part.

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Andrew Dunkley: Uh, radius of

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900 light years.

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Okay, let's see what happens here.

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Um, I'll just make sure I ask the question

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correctly.

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Ah, nothing. Oh, here we go. Uh, uh,

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ah, it's saying 10 to

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15 million.

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Professor Fred Watson: Yeah. Um, which is different from the

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calculation I saw, which is 10 million in a

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thousand. So drop it down a bit. Can you put

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it down to 500 light years, see what it says

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for that. Okay. This is AI, I assume that

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is doing all this for you on

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Mr. Google.

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Andrew Dunkley: I absolutely love it. Um, two

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to two and a half million stars.

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Professor Fred Watson: Yeah. So it's somewhere between 500

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and 1,000 light years.

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Andrew Dunkley: There you go.

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Professor Fred Watson: So you put in whatever number you like, and

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it will give you the right answer. Uh, Justin

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can have a lot of fun doing that. It's a

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great question, actually.

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Andrew Dunkley: Just working out the averages. So

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750 light years transposes to

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7 to 8 million stars. So.

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Professor Fred Watson: Yeah.

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Andrew Dunkley: Yeah, there you go. You could

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do this all day, really.

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Professor Fred Watson: Um, I don't think we've ever been asked that

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before.

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Andrew Dunkley: No, I don't think so either.

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Professor Fred Watson: Not in that. That way. Um, we have had

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questions about, you know, the density. The

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average density of stars in the solar

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neighborhood, and that's really what this is

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all about.

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Andrew Dunkley: Yeah.

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Professor Fred Watson: Uh, but, uh, yeah, good stuff, Justin.

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Thank you for your question and greetings to

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Melbourne. It's 42 in Melbourne today, I

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think.

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Andrew Dunkley: Yes. Um, we've. We'. I've got 38 here

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today. I went and played golf in that this

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morning, and, uh, I was. What's the word I

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used? One of my friends used to use a lot

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when he was tired. I was jiggered by the end

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of it.

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Professor Fred Watson: That's a good.

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Andrew Dunkley: I don't know where it comes from.

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Professor Fred Watson: My granddad used to use that. Yeah, yeah.

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Justin: Ah.

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Professor Fred Watson: Uh, wheel it in. It's jiggered.

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Andrew Dunkley: Yeah, it was, uh. It was a tough day out, I

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must say. Uh, thanks, Justin.

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Our next question comes from Charles. Uh,

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but because I've been using, uh, ChatGPT

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to solve all the riddles of the universe,

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I've lost the question. All right. If

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the universe does cease expanding

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and retracts, does that mean the lifetime of

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the universe goes from, uh, untold

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trillion, beyond trillions of years

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or just a, um, measly few billion?

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This one comes from Charles in Brooklyn. In

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New York. I was in Brooklyn not so long ago.

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Walked across the Brooklyn Bridge. Yeah, in

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about August, it was m.

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Professor Fred Watson: Were you jiggered when you got to the end?

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Andrew Dunkley: I was jiggered before I started because we'd

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been walking all day.

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Professor Fred Watson: Yeah, I can imagine. Um, I think Charles

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is right, actually. Uh, look,

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it may still.

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I mean, the difference is really that

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if we have a universe which

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is dominated by a constant, uh,

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um, dark energy term. In other words,

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something that puts more energy into the

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expansion of space. As the expansion. As

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space gets bigger, uh, that means it will go

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on expanding forever. Um, so. And

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Charles has summarized that by untold

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trillions beyond trillions, which I guess is

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forever. Uh, but if the dark

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energy is reducing, and that's

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certainly being hinted at by the latest

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observations, then um,

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we don't know what's going to happen

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because we don't know how quickly it's

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reducing and whether it may even go negative.

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So that suddenly there's a positive

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attraction of stuff, it's not being repelled

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like it is now, that could bring it down to a

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few billion years. Uh, but if it just

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goes settles back to something where

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it's the normal gravitational content of the

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universe that dominates everything, uh, and

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so in other words all the galaxies are

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pulling each other together, uh, then

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you might be talking about a bit longer. It

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might still be a few trillion years rather

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than a few measly billions. Uh, but,

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ah, interesting question. A nice thought

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experiment there from Charles in Brooklyn.

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Andrew Dunkley: Yes, indeed. And as

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you said, the theory about like

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I think I've said it before, when I was

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growing up, it was always assumed that the

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universe would stop expanding and then start

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sort of folding back in on itself. Uh, the

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Big Crunch or the gnab.

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Professor Fred Watson: Gib, whatever you want to call it.

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Andrew Dunkley: But um, then it was decided

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that uh, it was going to continue expanding

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at an accelerating rate. Now they've decided

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and that could lead to a Big Rip. But now

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it's looking more like the acceleration

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is slowing and now

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all the bets are off and we're back to, back

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to square one or something. I'm not sure.

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Yeah. How do you prove it? Well, I mean

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you can measure that. What's going on?

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Professor Fred Watson: Yeah, and that's the trick. I mean

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if we'd been having this conversation a year

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ago, we'd have been completely sold on

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the Big Rip because there was nothing to

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suggest that the expansion was going to slow

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down. The expansion was known to be

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accelerating. That was discovered in 1998.

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Um, but it's only within the last year with

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um, results from project called desi,

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uh, the Dark Energy

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Survey Instrument I think is the right thing.

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Uh, but that's basically established

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that uh. Established is the wrong word. It

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has suggested that the acceleration

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is slower now than it was

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a couple of billion years ago. Uh, and

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that uh, is leading people

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to the hint that maybe the acceleration will

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eventually not be there. And that's why we

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might get the gnab Gib. But I think we're

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still talking about, I think, really think

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it's trillions of years into the future.

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Andrew Dunkley: It's m like blowing up a balloon though when

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you start it goes out fast, but as it gets

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bigger, uh, the expansion continues, but

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it just, it slows down. It's the same

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thing.

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Professor Fred Watson: Okay.

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Andrew Dunkley: Maybe not. It does remind me, um, we

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got a question in German the other day

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because apparently now what they're doing on

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YouTube Music, the people who listen to us on

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YouTube Music is, uh,

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English speaking. YouTube Music

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podcasts are being translated into other

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languages. So apparently we were

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being heard in German, and a German listener

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on YouTube Music sent us a question in

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German and we had to translate

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it into English so that we knew what he was

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asking. But I don't think it translated very

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well. But it was something about, how do you

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prove the expansion of the universe

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if you haven't found a particle?

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Professor Fred Watson: Well, I wasn't sure whether I did look at

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that question. In fact, I did send an answer

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which I think, um, Huw might have put through

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some language mangling, um,

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system to give the answer in German.

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Uh, mein Deutsch is

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crap. Uh, so, um,

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that's K R A double P. It's

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not, uh,

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uh, so, um, I think. I wasn't sure

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whether it was somebody talking about dark

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energy or dark matter. Yeah, I wasn't sure

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either. But dark matter, yes, we do need to

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know what the particles are. And, um, I hope

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we'll discover them. I. I'm not optimistic.

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M. We're going to find that out during 2026,

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but you never know.

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Andrew Dunkley: Anything's possible. Thanks for your

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question, Charles.

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This is Space Nuts, uh, Q and A edition with

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Andrew Dunkley and Fred Watson.

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Andrew Dunkley: Now, let's take a break from the show to tell

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SpaceNuts 3,

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2,

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1. Space

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00:14:24.360 --> 00:14:25.080
nuts.

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Andrew Dunkley: Uh, next up we've got Dean who's got

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a kind of a what if question for. I love

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these, Fred. These are my favourite

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questions. What if this happens?

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Andrew Dunkley: Hi Fred and Andrew, this is Dean in Redcliffe

348
00:14:37.370 --> 00:14:39.490
in Queensland. Thanks for answering my

349
00:14:39.490 --> 00:14:42.330
previous questions. Today I'm asking about

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a thought experiment that was once used to

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consider issues around the speed of light. I

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think it may have been Einstein. The scenario

353
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asks what happens if our uh, sun suddenly

354
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disappears and would the sudden lack of

355
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gravity affect the earth instantly or would

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there be a delay if the gravity effect

357
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travels at a particular speed? Before

358
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I get to my actual question, I want to ask

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about thought experiments. They seem like a

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useful tool to get started on a problem, but

361
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I question the value of an experiment where

362
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the uh, initial proposition is impossible.

363
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The mass of the sun can't actually just

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disappear. So maybe basing conclusions

365
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from this is not reliable. What are your

366
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thoughts? However, if I just focus on the

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idea of the sun disappearing, I'd say that

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gravity is not a force generated by the sun,

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but is a compression of the spacetime around

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it. If the sun disappeared

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instantly, then space time would decompress

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back to a smooth state, except for the

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planets and moons still in the vicinity.

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There would also have to be an unwinding of

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the frame dragging around where the sun was.

376
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Let me know if I'm wrong, but it seems to me

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that a sudden decompression and unwinding of

378
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some local space time would be violent but

379
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uh, would not be instant.

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Imagine the 2D model of this using

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a large rubber sheet with a heavy ball in the

382
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center representing the sun. If you suddenly

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removed the ball, then the warped sheet would

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snap back into a flat plane quickly,

385
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but not instantly.

386
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Spacetime is very stiff. Maybe the Earth

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would start to feel some effect very

388
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quickly, but there would be a smooth

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transition to the complete lack of

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sun's gravity while the local spacetime is

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settling into a decompressed state.

392
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I also expect there would be a compression

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wave that is a uh, gravity wave generated

394
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from an event like this. What do you think?

395
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Andrew Dunkley: There's a lot packaged into that. Thank, uh,

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00:16:41.820 --> 00:16:42.420
you Dean.

397
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Uh, so there's a question or two questions

398
00:16:45.020 --> 00:16:47.540
effectively uh, that he's asking about,

399
00:16:48.270 --> 00:16:50.420
um, what's the worth of thought

400
00:16:50.500 --> 00:16:52.900
experiments? Uh, now

401
00:16:54.260 --> 00:16:57.210
yeah, I did

402
00:16:57.210 --> 00:16:58.570
a Little bit of research while I was

403
00:16:58.570 --> 00:17:01.330
listening to him. And to give you an idea of

404
00:17:01.330 --> 00:17:03.890
thought experiments, um, there have been many

405
00:17:03.890 --> 00:17:05.850
famous ones over the years. Schrodinger's

406
00:17:05.850 --> 00:17:08.850
cat, Galileo's, uh, falling

407
00:17:08.850 --> 00:17:11.730
bodies. Um, there's

408
00:17:11.730 --> 00:17:13.410
one called the Trolley Problem. I have to

409
00:17:13.410 --> 00:17:15.050
look into that. Don't know what that one is.

410
00:17:15.050 --> 00:17:17.770
But, um, yeah, they have been very

411
00:17:17.770 --> 00:17:20.090
helpful over the years. I do think there is

412
00:17:20.090 --> 00:17:23.090
worth in thought experiments. It's a

413
00:17:23.090 --> 00:17:25.090
way of exploring something that we can't

414
00:17:25.090 --> 00:17:26.850
solve yet because we haven't got the

415
00:17:26.850 --> 00:17:29.590
technology to solve it. But it

416
00:17:29.590 --> 00:17:31.790
gives you something to work with and it

417
00:17:31.790 --> 00:17:34.590
tosses around ideas that may provide

418
00:17:34.670 --> 00:17:37.550
solutions. It's, um. I think.

419
00:17:38.670 --> 00:17:40.590
I love the concept. I think it's very

420
00:17:40.590 --> 00:17:43.229
valuable. It's how we start making

421
00:17:43.229 --> 00:17:45.470
inquiries with thought experiments.

422
00:17:46.110 --> 00:17:48.830
If we didn't use our imaginations, then we

423
00:17:48.830 --> 00:17:50.190
probably wouldn't solve anything.

424
00:17:50.990 --> 00:17:53.870
Professor Fred Watson: Exactly. Um, a great answer, actually.

425
00:17:53.870 --> 00:17:56.780
Andrew. Thank you. Um, I'll. I'll just

426
00:17:56.780 --> 00:17:59.700
go home and. No,

427
00:17:59.780 --> 00:18:02.340
I entirely agree. Um, the one that came to my

428
00:18:02.340 --> 00:18:05.020
mind was a thought experiment that, had the

429
00:18:05.020 --> 00:18:07.330
real experiment been carried out, physics,

430
00:18:07.330 --> 00:18:09.460
uh, would have ground to a halt very quickly.

431
00:18:09.700 --> 00:18:12.580
And that's, uh, Einstein's

432
00:18:12.660 --> 00:18:14.980
musing in 1907

433
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about what would happen if he jumped off the

434
00:18:17.980 --> 00:18:20.540
top of the Patents Building in Berne, which

435
00:18:20.540 --> 00:18:22.180
is where he was working at the time. He was a

436
00:18:22.180 --> 00:18:25.110
patent administrator. Uh, and so

437
00:18:25.110 --> 00:18:26.830
he imagined himself jumping off the top of

438
00:18:26.830 --> 00:18:29.070
the building. Uh, so if he carried that out

439
00:18:29.070 --> 00:18:30.710
as a real experiment, that could have been

440
00:18:30.710 --> 00:18:33.150
the end of a lot of really good stuff. Yeah.

441
00:18:34.170 --> 00:18:36.910
Uh, but what it gave him was the inspiration

442
00:18:37.950 --> 00:18:40.630
to, um, define what we now call the

443
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principle of equivalence. The fact that

444
00:18:42.830 --> 00:18:45.290
acceleration and gravity are, uh,

445
00:18:45.950 --> 00:18:48.760
to all intents and purposes, the same. Um,

446
00:18:49.390 --> 00:18:51.910
so. And the fact that you're accelerating

447
00:18:51.910 --> 00:18:54.390
towards the Earth, uh, cancels out the

448
00:18:54.390 --> 00:18:56.310
Earth's gravity because the two are exactly

449
00:18:56.310 --> 00:18:57.770
equal. And that's why

450
00:18:59.050 --> 00:19:01.770
as you jump off the building, uh, your pipe

451
00:19:01.770 --> 00:19:03.730
floats out of your mouth. If you've got money

452
00:19:03.730 --> 00:19:05.410
in your hands or something like that, it just

453
00:19:05.410 --> 00:19:07.330
floats away. You can actually demonstrate it

454
00:19:07.330 --> 00:19:09.650
very easily on a trampoline, uh, without

455
00:19:09.650 --> 00:19:11.330
jumping off buildings. But it was that

456
00:19:11.330 --> 00:19:13.410
thought experiment that led to the principle

457
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of equivalence, which told Einstein that

458
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gravity is actually a geometrical problem

459
00:19:19.370 --> 00:19:22.250
rather than, you know, something entwined

460
00:19:22.250 --> 00:19:24.770
in physics. We know it is. We still don't

461
00:19:24.770 --> 00:19:26.650
really understand the physics of gravity, but

462
00:19:26.650 --> 00:19:29.360
the geometry works so well. Well, uh,

463
00:19:29.590 --> 00:19:32.230
in the general, uh, theory of relativity

464
00:19:32.470 --> 00:19:34.830
that, um, the principle of equivalence has

465
00:19:34.830 --> 00:19:37.550
been demonstrated to be accurate to within

466
00:19:37.550 --> 00:19:39.590
one part, uh, in 10 to the 18 or something. I

467
00:19:39.590 --> 00:19:42.580
can't remember what the latest thing is, uh,

468
00:19:42.580 --> 00:19:45.220
that it does work very, very well indeed. Uh,

469
00:19:45.270 --> 00:19:47.700
so yes, thought experiments are great. Um,

470
00:19:47.990 --> 00:19:49.990
now the thought experiment regarding taking

471
00:19:49.990 --> 00:19:51.870
the sun out the solar system is very well

472
00:19:51.870 --> 00:19:54.790
established as to what happens. Uh,

473
00:19:55.350 --> 00:19:57.270
the Earth feels nothing for the first eight

474
00:19:57.270 --> 00:20:00.160
minutes, uh, because gravitational energy

475
00:20:00.160 --> 00:20:02.890
travels at the same speed as light. Uh,

476
00:20:02.890 --> 00:20:05.800
and once, um, the message

477
00:20:05.800 --> 00:20:08.720
that there is no gravitating body

478
00:20:08.960 --> 00:20:11.080
in the center of the solar system reaches the

479
00:20:11.080 --> 00:20:13.200
Earth eight minutes after the sun has gone,

480
00:20:13.660 --> 00:20:15.680
um, the Earth just carries on in a straight

481
00:20:15.680 --> 00:20:18.640
line. Uh, ah,

482
00:20:18.800 --> 00:20:21.760
so, uh, that's well understood. So,

483
00:20:22.420 --> 00:20:25.060
um, I think, uh, um,

484
00:20:25.160 --> 00:20:27.960
Dean's um, thinking uh, about

485
00:20:28.040 --> 00:20:30.440
the, you know, the, the two dimensional

486
00:20:30.760 --> 00:20:33.160
idea of the gravity well, uh, which is a

487
00:20:33.160 --> 00:20:35.840
great way of thinking of the way, uh, mass

488
00:20:35.840 --> 00:20:38.800
distorts time. Uh, we're used to

489
00:20:38.800 --> 00:20:41.520
thinking, okay, you've got a rock in the

490
00:20:41.520 --> 00:20:43.520
middle of a trampoline. It's pulling it down,

491
00:20:43.520 --> 00:20:45.040
you take the rock away, the trampoline just

492
00:20:45.040 --> 00:20:47.760
springs back. Uh, but actually, uh, it

493
00:20:47.760 --> 00:20:50.720
wouldn't. The space time would take, uh,

494
00:20:50.890 --> 00:20:53.810
time, uh, basically the message that

495
00:20:53.810 --> 00:20:56.130
it had sprung back would take, would travel

496
00:20:56.130 --> 00:20:58.650
outwards at the speed of light. Uh, and so

497
00:20:58.650 --> 00:21:00.370
it's the same, you know, the same thing

498
00:21:00.370 --> 00:21:03.090
looking at it either as a gravity well or

499
00:21:03.090 --> 00:21:05.770
as gravitational energy or radiation.

500
00:21:06.170 --> 00:21:07.730
One day we'll have a quantum theory of

501
00:21:07.730 --> 00:21:09.010
gravity and we'll be able to talk about

502
00:21:09.010 --> 00:21:11.090
gravitons, uh, which are, uh, the

503
00:21:11.090 --> 00:21:13.410
hypothetical particles that carry gravity and

504
00:21:13.410 --> 00:21:14.730
they move at the speed of light.

505
00:21:15.050 --> 00:21:17.490
Andrew Dunkley: Of course, we should mention the catastrophe

506
00:21:17.490 --> 00:21:19.890
that would then follow 8 minutes after the

507
00:21:19.890 --> 00:21:22.470
sun suddenly disappeared. 4 example.

508
00:21:22.470 --> 00:21:25.110
Pavlov's dog and Schroding's Schrodinger's

509
00:21:25.110 --> 00:21:25.990
cat would live together.

510
00:21:26.310 --> 00:21:29.110
Professor Fred Watson: Yes. So they would.

511
00:21:30.070 --> 00:21:33.030
Yeah. Oh, deary me. Uh, that's. Yes.

512
00:21:34.470 --> 00:21:37.470
Andrew Dunkley: Would be a mess. How long would the

513
00:21:37.470 --> 00:21:39.030
Earth last after that effect?

514
00:21:39.920 --> 00:21:41.910
Professor Fred Watson: Uh, it would be fine. It would just keep on

515
00:21:41.910 --> 00:21:43.630
going. Um, you know, assuming there wasn't

516
00:21:43.630 --> 00:21:45.980
some sort of, um, uh,

517
00:21:45.980 --> 00:21:47.910
catastrophic event that caused the sun to

518
00:21:47.910 --> 00:21:50.310
disappear. If you just remove the sun without

519
00:21:50.760 --> 00:21:53.280
anything, explodes anything, which you can do

520
00:21:53.280 --> 00:21:55.920
in a thought experiment, the Earth just

521
00:21:55.920 --> 00:21:57.640
keeps, keeps on going. It will be like

522
00:21:57.640 --> 00:21:59.480
Voyager 1 and Voyager 2. It will get very,

523
00:21:59.480 --> 00:22:02.120
very cold. Uh, we as a species will almost

524
00:22:02.120 --> 00:22:04.800
certainly not survive, uh, because the

525
00:22:04.800 --> 00:22:06.960
temperatures would plummet to very low levels

526
00:22:06.960 --> 00:22:09.780
indeed. Um, so yes, uh,

527
00:22:09.780 --> 00:22:11.080
an interesting scenario.

528
00:22:11.880 --> 00:22:13.160
Andrew Dunkley: Doesn't sound like much fun.

529
00:22:13.240 --> 00:22:13.880
Professor Fred Watson: It's not fun.

530
00:22:13.880 --> 00:22:14.680
Andrew Dunkley: No. No.

531
00:22:14.680 --> 00:22:16.120
Professor Fred Watson: Anyway, think about it though.

532
00:22:16.200 --> 00:22:19.130
Andrew Dunkley: We're stuck with um, with the

533
00:22:19.130 --> 00:22:21.210
sun for Several more billion years.

534
00:22:22.010 --> 00:22:23.850
Professor Fred Watson: Yes, indeed we are.

535
00:22:25.290 --> 00:22:27.410
Andrew Dunkley: But, uh, great questions, Dean. I really

536
00:22:27.410 --> 00:22:30.240
enjoy those kinds of questions. So, uh,

537
00:22:30.240 --> 00:22:31.530
yeah, thanks for sending it in.

538
00:22:33.210 --> 00:22:34.490
Let's take a break from the show.

539
00:22:34.490 --> 00:22:36.450
Andrew Dunkley: To tell you about our, uh, sponsor, uh, anti

540
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541
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542
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543
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544
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547
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548
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550
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553
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555
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556
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559
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560
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561
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562
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566
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569
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on the link in the show notes.

571
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Andrew Dunkley: 3, 2, 1.

572
00:24:03.340 --> 00:24:04.540
Andrew Dunkley: Space nuts.

573
00:24:05.180 --> 00:24:08.060
Andrew Dunkley: Our, uh, final question today comes from

574
00:24:08.060 --> 00:24:10.340
Patrick. He's a conspiracy theorist. Well,

575
00:24:10.340 --> 00:24:12.340
he's probably not, but I do like this

576
00:24:12.340 --> 00:24:14.660
question because I, I didn't know this.

577
00:24:15.300 --> 00:24:17.940
Uh, the Voyager spacecraft have plaques on

578
00:24:17.940 --> 00:24:20.660
them. I did know that. And as far as I can

579
00:24:20.660 --> 00:24:23.100
find out, both show them leaving the solar

580
00:24:23.100 --> 00:24:25.700
system ecliptic, um, between

581
00:24:25.940 --> 00:24:28.820
Jupiter and Saturn. That didn't happen.

582
00:24:29.379 --> 00:24:32.100
And from what I've read, Voyager 1 left after

583
00:24:32.100 --> 00:24:34.660
a visit to Titan while Voyager, uh, 2

584
00:24:34.740 --> 00:24:37.060
carried on. Uh, Voyager 1,

585
00:24:38.400 --> 00:24:41.280
uh, had a chance to visit Pluto. So his the

586
00:24:41.280 --> 00:24:44.120
questions. Why does the plaque show an early

587
00:24:44.120 --> 00:24:46.920
departure of Voyager 1? And why does Voyager

588
00:24:46.920 --> 00:24:49.680
2's path show the same? Um,

589
00:24:49.680 --> 00:24:52.160
hope you both had a wonderful Christmas and

590
00:24:52.600 --> 00:24:55.600
um, hello from a wet northern island.

591
00:24:56.320 --> 00:24:59.240
Patrick. Wet Northern Ireland. It's probably

592
00:24:59.240 --> 00:25:01.680
still wet, just like we're still dry.

593
00:25:02.080 --> 00:25:04.200
We've hit the hottest, driest part of the

594
00:25:04.200 --> 00:25:07.040
year in Australia and, um, it is dry as a

595
00:25:07.040 --> 00:25:09.600
chip, as we say in this country

596
00:25:10.080 --> 00:25:12.600
at the moment. Um, yeah,

597
00:25:12.600 --> 00:25:15.280
okay. I didn't realize that the plaques had

598
00:25:15.280 --> 00:25:17.880
the supposed path of both

599
00:25:17.880 --> 00:25:20.640
spacecraft, but they didn't go that way. Did

600
00:25:20.640 --> 00:25:22.880
they get pulled over by an RBT Perhaps.

601
00:25:24.660 --> 00:25:27.360
Professor Fred Watson: Um, I thought you'd have spotted this one

602
00:25:27.840 --> 00:25:29.440
right at the start, Andrew.

603
00:25:29.680 --> 00:25:32.560
Andrew Dunkley: Really? Is he

604
00:25:32.560 --> 00:25:33.280
playing us?

605
00:25:33.800 --> 00:25:36.570
Professor Fred Watson: Uh, no, he's got his spacecraft mixed up.

606
00:25:36.880 --> 00:25:39.120
Because it's the two, the two pioneers

607
00:25:39.600 --> 00:25:42.120
that show the spacecraft leaving the solar

608
00:25:42.120 --> 00:25:45.040
system between orbits of Jupiter.

609
00:25:45.280 --> 00:25:46.720
Andrew Dunkley: I never even thought of that.

610
00:25:47.920 --> 00:25:50.040
Professor Fred Watson: Voyager doesn't actually have a diagram like

611
00:25:50.040 --> 00:25:52.120
that on it. It's got mostly diagrams how to

612
00:25:52.120 --> 00:25:53.360
play the Golden Record.

613
00:25:53.680 --> 00:25:54.400
Andrew Dunkley: That's right.

614
00:25:54.540 --> 00:25:57.280
Professor Fred Watson: Um, so it's the Pioneer spacecraft. So

615
00:25:57.280 --> 00:26:00.200
Patrick, you, your, your question's a good

616
00:26:00.200 --> 00:26:03.010
one, but I think the premise is

617
00:26:03.010 --> 00:26:05.010
wrong. It's not the Voyager spacecraft that

618
00:26:05.010 --> 00:26:06.570
had the diagram, it's the pioneers.

619
00:26:06.730 --> 00:26:09.690
Andrew Dunkley: Well, how about that? Yeah, I'm

620
00:26:09.690 --> 00:26:11.610
just looking at them now. Okay.

621
00:26:13.130 --> 00:26:15.850
That's really. And it's got the human

622
00:26:15.850 --> 00:26:16.650
being on it.

623
00:26:17.290 --> 00:26:19.350
Professor Fred Watson: I actually really like the Pioneer, uh,

624
00:26:19.350 --> 00:26:21.490
plaques. I think they're elegant and

625
00:26:21.490 --> 00:26:24.170
decorative and tell, um, the story.

626
00:26:24.330 --> 00:26:26.170
Just show aliens just how

627
00:26:27.050 --> 00:26:28.500
chewy we are and you know.

628
00:26:28.970 --> 00:26:29.290
Andrew Dunkley: Yeah.

629
00:26:29.450 --> 00:26:31.770
Professor Fred Watson: How tasty we might be and how.

630
00:26:31.860 --> 00:26:34.530
Andrew Dunkley: Um, unfortunate that male appendage is.

631
00:26:34.530 --> 00:26:36.970
It's well below par, but.

632
00:26:38.570 --> 00:26:40.970
And the other factor is that.

633
00:26:41.130 --> 00:26:42.010
Professor Fred Watson: Thanks, Andrew.

634
00:26:42.490 --> 00:26:44.890
Andrew Dunkley: Aliens will look at these two human figures

635
00:26:44.890 --> 00:26:47.770
and they'll go, she does

636
00:26:47.770 --> 00:26:48.810
not like him.

637
00:26:50.490 --> 00:26:51.210
Professor Fred Watson: That's right.

638
00:26:51.290 --> 00:26:53.210
Andrew Dunkley: The body language is not positive.

639
00:26:53.930 --> 00:26:56.090
Professor Fred Watson: That's true. There is body language on there

640
00:26:56.090 --> 00:26:58.920
that really. Yeah, I'm with you on M. That

641
00:26:58.920 --> 00:27:01.840
actually. It's all about

642
00:27:01.840 --> 00:27:03.120
body language. Yeah.

643
00:27:03.120 --> 00:27:05.360
Andrew Dunkley: So now I'm going to have to look up what the

644
00:27:05.360 --> 00:27:07.000
Voyager plaques look like.

645
00:27:07.640 --> 00:27:08.370
Professor Fred Watson: Yeah. Ah, ah.

646
00:27:08.680 --> 00:27:11.160
Andrew Dunkley: See, it's. Yes. The Golden Record with the,

647
00:27:11.170 --> 00:27:14.120
um, bits and bobs on the stuff on

648
00:27:14.120 --> 00:27:16.280
it. Yeah, yeah. Okay.

649
00:27:17.560 --> 00:27:20.040
So, um, right idea. Wrong.

650
00:27:20.200 --> 00:27:22.720
Wrong spacecraft is basically the answer to

651
00:27:22.720 --> 00:27:23.160
the question.

652
00:27:24.510 --> 00:27:25.870
Professor Fred Watson: Uh, I think that's correct.

653
00:27:27.830 --> 00:27:30.230
Andrew Dunkley: Um, I think we can safely say that Voyager 1

654
00:27:30.230 --> 00:27:32.470
and Voyager 2 did go where we intended them

655
00:27:32.470 --> 00:27:35.150
to go. And they're still going.

656
00:27:35.310 --> 00:27:37.030
Professor Fred Watson: Yeah, indeed they are. Voyager 2, well,

657
00:27:37.030 --> 00:27:39.910
Pioneer 10 and 11 are as well. Uh, Voyager

658
00:27:39.910 --> 00:27:42.310
2 was the one that flew by Uranus, uh, and

659
00:27:42.310 --> 00:27:44.750
Neptune as well as Jupiter and Saturn.

660
00:27:44.910 --> 00:27:47.470
Fantastic details that came from those two

661
00:27:47.470 --> 00:27:50.270
spacecraft. Voyager 1, as we've said many

662
00:27:50.270 --> 00:27:53.080
times before, is the most distant human

663
00:27:53.160 --> 00:27:56.040
made object and is still on

664
00:27:56.040 --> 00:27:58.880
its way. It's almost a light day away. We

665
00:27:58.880 --> 00:28:00.800
should have a little party at Space Nuts when

666
00:28:00.800 --> 00:28:03.600
it crosses a light day. Um, the light

667
00:28:03.600 --> 00:28:04.880
day boundary. Yeah.

668
00:28:04.880 --> 00:28:07.280
Andrew Dunkley: Which, uh, is happening in about 500 years

669
00:28:07.280 --> 00:28:10.080
from now. No, I'm not sure. It can't be that

670
00:28:10.080 --> 00:28:10.440
far away.

671
00:28:10.440 --> 00:28:12.200
Professor Fred Watson: Yeah, it's a few years. Yeah, a couple of

672
00:28:12.200 --> 00:28:14.520
years. I think it's about 23 light hours at

673
00:28:14.520 --> 00:28:17.480
the moment. Uh, so it'll be. Yes. Four or

674
00:28:17.480 --> 00:28:17.960
five years.

675
00:28:18.280 --> 00:28:20.370
Andrew Dunkley: Yeah. Wow. Yeah, we thought we should do

676
00:28:20.370 --> 00:28:21.610
something special about that.

677
00:28:22.010 --> 00:28:22.490
Professor Fred Watson: Yes.

678
00:28:22.780 --> 00:28:25.330
Andrew Dunkley: M. All right. Um, well, that was easily

679
00:28:25.330 --> 00:28:26.660
solved. Thanks for the question, though. Uh,

680
00:28:26.660 --> 00:28:29.370
Patrick. It sort of. Yeah, it reminds us

681
00:28:29.370 --> 00:28:31.650
that, uh, as time goes on, you can sort of

682
00:28:31.650 --> 00:28:34.010
mix two totally different things

683
00:28:34.810 --> 00:28:35.610
together and.

684
00:28:36.330 --> 00:28:38.650
Yeah, it throws. Throws your brain out.

685
00:28:39.640 --> 00:28:42.330
Um, it reminds me of a story once where,

686
00:28:42.480 --> 00:28:45.410
um. Oh, gosh, a guy I

687
00:28:45.410 --> 00:28:47.610
worked with in radio did a special about,

688
00:28:47.840 --> 00:28:50.650
um, uh, Dean Martin and

689
00:28:50.650 --> 00:28:52.650
Jerry Lewis getting back together. Remember

690
00:28:52.650 --> 00:28:52.930
them?

691
00:28:52.930 --> 00:28:53.370
Professor Fred Watson: Yeah.

692
00:28:53.370 --> 00:28:56.210
Andrew Dunkley: Yeah, but he thought it was Jerry Lee Lewis,

693
00:28:57.650 --> 00:28:59.850
so he did this whole special with Jerry Lee

694
00:28:59.850 --> 00:29:00.530
Lewis music.

695
00:29:02.930 --> 00:29:05.650
Completely wrong. Yes, but it can

696
00:29:05.650 --> 00:29:05.970
happen.

697
00:29:06.130 --> 00:29:08.560
Professor Fred Watson: It can happen. Yeah, I, um.

698
00:29:09.330 --> 00:29:11.490
Yes, I looked at some research recently where

699
00:29:11.490 --> 00:29:14.120
they'd got the wrong telescope. Uh,

700
00:29:14.130 --> 00:29:15.570
yeah, well, it's like getting the.

701
00:29:15.570 --> 00:29:17.170
Andrew Dunkley: Color of the universe wrong when you make.

702
00:29:17.170 --> 00:29:19.010
Professor Fred Watson: That's another one. That's correct. Yes.

703
00:29:19.280 --> 00:29:19.600
Yeah.

704
00:29:20.800 --> 00:29:23.080
Andrew Dunkley: Oh, there's a list of them. There's a list of

705
00:29:23.080 --> 00:29:25.320
them. So don't feel bad, Patrick. It happens

706
00:29:25.320 --> 00:29:27.880
to the best of us. Uh, but thanks for the

707
00:29:27.880 --> 00:29:29.520
question. Lovely to hear from you. If you've

708
00:29:29.520 --> 00:29:31.760
got questions for us, please send them in to

709
00:29:31.760 --> 00:29:33.960
us via our website. Just go to

710
00:29:33.960 --> 00:29:36.720
spacenutspodcast.com or

711
00:29:36.720 --> 00:29:39.320
spacenuts IO if you're a lazy

712
00:29:39.320 --> 00:29:42.160
typist, and click on the AMA

713
00:29:42.160 --> 00:29:44.480
button up the top, and, uh, you can send us

714
00:29:44.480 --> 00:29:46.480
text and audio questions that away.

715
00:29:47.230 --> 00:29:48.640
Uh, we sometimes get them through

716
00:29:48.640 --> 00:29:50.040
YouTube Music, so if you're a YouTube Music

717
00:29:50.040 --> 00:29:52.430
listener, please, uh, send them in. Be, um,

718
00:29:52.580 --> 00:29:55.580
happy to hear from you. Uh, and don't forget

719
00:29:55.580 --> 00:29:57.820
reviews. We. We really appreciate your

720
00:29:57.820 --> 00:30:00.790
reviews. The more reviews, the better. I, um,

721
00:30:00.900 --> 00:30:03.180
mean, it's an astronomy podcast, so,

722
00:30:03.740 --> 00:30:06.340
you know, um, five stars would be the

723
00:30:06.340 --> 00:30:09.300
absolute minimum I would expect. That's up

724
00:30:09.300 --> 00:30:12.180
to you. No influence here. No influence

725
00:30:12.180 --> 00:30:12.420
here.

726
00:30:12.420 --> 00:30:13.500
Professor Fred Watson: Four million stars.

727
00:30:13.500 --> 00:30:15.900
Andrew Dunkley: Four million stars. Yes. Deal.

728
00:30:16.490 --> 00:30:18.820
Uh, and, um, yeah, if you'd like to do that

729
00:30:18.820 --> 00:30:20.620
for us, that'd be great. And don't forget to,

730
00:30:20.830 --> 00:30:23.290
um, check out our website if, uh, you. To,

731
00:30:23.290 --> 00:30:26.200
uh, support us. Some people do through, um,

732
00:30:26.280 --> 00:30:29.200
Patreon and Supercast. Uh, there's

733
00:30:29.200 --> 00:30:32.040
a little button where it says, support our

734
00:30:32.040 --> 00:30:34.800
podcasts. So click that button, you can find

735
00:30:34.800 --> 00:30:36.680
out more about it. It's totally voluntary.

736
00:30:37.420 --> 00:30:39.360
Um, Fred, we are done. Thank you so much for

737
00:30:39.360 --> 00:30:40.440
answering those questions.

738
00:30:40.840 --> 00:30:42.600
Professor Fred Watson: Oh, uh, it's a pleasure. It's, um, always

739
00:30:42.600 --> 00:30:44.960
good to interact with our, uh, four

740
00:30:44.960 --> 00:30:47.920
listeners. Yes, we've

741
00:30:47.920 --> 00:30:49.080
only got four at a time.

742
00:30:50.680 --> 00:30:53.080
Yeah, no, it's good. And thank you very much.

743
00:30:53.200 --> 00:30:55.620
Uh, again, as always, Andre, for being the

744
00:30:55.620 --> 00:30:56.660
host of Space Notes.

745
00:30:56.660 --> 00:30:58.900
Andrew Dunkley: Oh, my great pleasure. It's good fun,

746
00:30:59.140 --> 00:31:00.940
Professor, Uh, Fred Watson, astronomer at

747
00:31:00.940 --> 00:31:02.380
large. He'll join us again on the next

748
00:31:02.380 --> 00:31:04.740
episode. Uh, and Huw in the studio couldn't

749
00:31:04.740 --> 00:31:06.700
be with us today because he was doing a

750
00:31:06.700 --> 00:31:09.540
thought experiment, uh, where

751
00:31:09.540 --> 00:31:10.500
he didn't exist.

752
00:31:13.620 --> 00:31:16.020
What more can I say? Uh, and from me, Andrew

753
00:31:16.020 --> 00:31:17.500
Dunkley, thanks for your company. We'll catch

754
00:31:17.500 --> 00:31:19.580
you on the next episode of Space Nuts. Bye.

755
00:31:19.580 --> 00:31:21.220
Bye. Space Nuts.

756
00:31:21.220 --> 00:31:23.340
Andrew Dunkley: You've been listening to the Space Nuts

757
00:31:23.340 --> 00:31:25.980
podcast, available

758
00:31:26.060 --> 00:31:28.380
at Apple Podcasts, Spotify,

759
00:31:28.460 --> 00:31:31.260
iHeartRadio, or your favorite podcast

760
00:31:31.260 --> 00:31:33.620
player. You can also stream on demand at

761
00:31:33.620 --> 00:31:34.300
bytes.

762
00:31:34.300 --> 00:31:34.420
Professor Fred Watson: Com.

763
00:31:34.420 --> 00:31:37.100
Andrew Dunkley: Um, this has been another quality podcast

764
00:31:37.100 --> 00:31:38.700
production from Bytes.

765
00:31:38.780 --> 00:31:38.900
Professor Fred Watson: Com.

766
00:31:38.900 --> 00:31:39.210
Andrew Dunkley: Um.