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Q&A Edition: Black Holes, Cosmic Expansion, and the Fate of the Sun
In this engaging Q&A episode of Space Nuts, hosts Andrew Dunkley and Professor Fred Watson tackle a series of thought-provoking questions from listeners. From the implications of a black hole's mass to the mysteries of cosmic expansion, this episode is packed with fascinating insights and cosmic curiosities.
Episode Highlights:
- Black Hole Mass and Star Density: Justin from Melbourne wonders about the radius in light years of a sphere containing the nearest 4 million stars, comparing it to the mass of Sagittarius A, the supermassive black hole at the center of our galaxy. Andrew and Fred discuss star density and the methods to calculate it.
- The Universe's Future: Charles from Brooklyn asks whether the universe's potential retraction would shorten its lifespan from trillions of years to just a few billion. The hosts delve into the complexities of dark energy and the various theories surrounding the fate of the universe.
- What If the Sun Disappeared? Dean from Queensland poses a thought experiment about the consequences of the sun's sudden disappearance. Andrew and Fred explain how gravity and light travel at the same speed, leading to an eight-minute delay before Earth feels the effects of the sun's absence.
- Voyager Plaque Mysteries: Patrick brings an intriguing question about the Voyager spacecraft and the accuracy of the plaques they carry. The hosts clarify the misconception and explore the significance of the messages sent into space.
For more Space Nuts, including our continuously updating newsfeed and to listen to all our episodes, visit our website. Follow us on social media at SpaceNutsPod on Facebook, X, YouTube Music Music, Tumblr, Instagram, and TikTok. We love engaging with our community, so be sure to drop us a message or comment on your favorite platform.
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Stay curious, keep looking up, and join us next time for more stellar insights and cosmic wonders. Until then, clear skies and happy stargazing.
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00:00:00 --> 00:00:02 Andrew Dunkley: Hi there. Thanks for joining us on a Q and A
00:00:02 --> 00:00:04 edition of Space Nuts, our first one for the
00:00:04 --> 00:00:07 year. My name is Andrew Dunkley, your host.
00:00:07 --> 00:00:09 And we've got questions from Justin,
00:00:10 --> 00:00:12 who's got, um, a sent us an audio
00:00:12 --> 00:00:15 question. Um, he's talking about the space
00:00:16 --> 00:00:18 that contains the equivalent to 4 million
00:00:18 --> 00:00:21 stars in comparison to a black, ah, hole, I
00:00:21 --> 00:00:23 think. Can't remember. I don't write down
00:00:23 --> 00:00:25 enough when I write down the descriptions of
00:00:25 --> 00:00:27 questions. Uh, Charles,
00:00:28 --> 00:00:31 you're right. Fred's saying the same thing.
00:00:31 --> 00:00:34 Uh, Charles says, um, is asking us
00:00:34 --> 00:00:37 a question about the retraction of, uh, the
00:00:37 --> 00:00:40 universe, the shrinking of it. Uh, and,
00:00:40 --> 00:00:43 uh, Dean is asking, uh, about what might
00:00:43 --> 00:00:45 happen if the sun instantaneously
00:00:45 --> 00:00:48 disappeared. What would be the effect on our
00:00:48 --> 00:00:51 solar system and our planet specifically. And
00:00:51 --> 00:00:54 Patrick has some thoughts about, uh, both the
00:00:54 --> 00:00:57 voyages one and two, mainly
00:00:57 --> 00:00:59 the fact that the data we've put on the
00:00:59 --> 00:01:01 plaques that have been put on board the
00:01:01 --> 00:01:04 Voyages is actually telling anyone who
00:01:04 --> 00:01:07 finds them a lie. That's all coming up
00:01:07 --> 00:01:10 in this edition of Space Butts. And
00:01:10 --> 00:01:13 with us once again to decipher all of that
00:01:13 --> 00:01:15 gibberish that I just mentioned. And it's not
00:01:15 --> 00:01:17 the questions that are gibberish, it's my
00:01:17 --> 00:01:19 interpretation of them is Professor Fred
00:01:19 --> 00:01:21 Watson, astronomer at large. Hello, Fred.
00:01:22 --> 00:01:25 Professor Fred Watson: Hi, Andrew. Your interpretation was more or
00:01:25 --> 00:01:27 less the same as what I thought when I saw
00:01:27 --> 00:01:29 them. So I think we're on the same
00:01:29 --> 00:01:30 wavelength, which is good.
00:01:30 --> 00:01:33 Andrew Dunkley: Okay. Okay, well, that's good. Uh, we
00:01:33 --> 00:01:35 might as well just hit them straight on the
00:01:35 --> 00:01:35 head.
00:01:35 --> 00:01:38 And our first question is an audio question.
00:01:38 --> 00:01:40 And this one comes from Justin.
00:01:40 --> 00:01:43 Justin: G', day, Andrew and Fred. I'm Justin down in
00:01:43 --> 00:01:45 Melbourne. Like Fred, I'm an
00:01:45 --> 00:01:48 expat POM and my astronomical claim to
00:01:48 --> 00:01:51 fame is that I witnessed the total solar
00:01:51 --> 00:01:53 eclipse in Cornwall in the UK in
00:01:53 --> 00:01:56 1999. Two friends and
00:01:56 --> 00:01:58 I camped nearby and joined the crowds at
00:01:58 --> 00:02:01 Newquay beach on that day for a
00:02:01 --> 00:02:03 lifetime bucket list event.
00:02:04 --> 00:02:07 So I have a mathematical question. I've often
00:02:07 --> 00:02:09 heard it said that the black hole at the
00:02:09 --> 00:02:12 center of the Milky Way galaxy Sagittarius A
00:02:12 --> 00:02:14 is 4 million solar masses.
00:02:15 --> 00:02:18 So for comparison, what would the
00:02:18 --> 00:02:20 radius be in light years of a
00:02:20 --> 00:02:23 sphere centered on the Earth that contains
00:02:23 --> 00:02:25 the nearest 4 million stars?
00:02:26 --> 00:02:27 Thanks very much.
00:02:28 --> 00:02:30 Andrew Dunkley: Thank you, Justin. Cornwall. That's where my
00:02:30 --> 00:02:33 family originated before
00:02:33 --> 00:02:36 they, um, they got sent out here. Now, I
00:02:36 --> 00:02:39 think they came voluntarily. We, we didn't
00:02:39 --> 00:02:41 come with the convicts. We, we came out
00:02:41 --> 00:02:43 later. But, um, yeah, Justin, good question.
00:02:43 --> 00:02:46 Four million stars. Um, what sort of Space
00:02:46 --> 00:02:49 would that take up in terms of a radius in
00:02:49 --> 00:02:51 light years? I think was the guts of his
00:02:51 --> 00:02:52 question.
00:02:52 --> 00:02:55 Professor Fred Watson: Yes. So, uh, a little bit more
00:02:55 --> 00:02:58 subtle than that. It's, it's saying if
00:02:58 --> 00:03:00 you, if you're sitting here on planet Earth,
00:03:01 --> 00:03:03 um, what sort of,
00:03:04 --> 00:03:07 you know, in our locality, uh, in the
00:03:08 --> 00:03:10 um, Western spiral,
00:03:11 --> 00:03:13 the galaxy, it's the Orion spur, where we
00:03:13 --> 00:03:16 are, uh, that spiral arm that we sit
00:03:16 --> 00:03:19 in. Um, what's the, it's so it's really
00:03:19 --> 00:03:21 a question about the density of stars in our
00:03:21 --> 00:03:24 region. Uh, and that's something very well
00:03:24 --> 00:03:26 established because we know the distances of
00:03:26 --> 00:03:29 lots of stars. Uh, so I'm
00:03:29 --> 00:03:32 going to put it in much rounder figures. Uh,
00:03:33 --> 00:03:36 uh, but if you
00:03:37 --> 00:03:40 look at uh, out to
00:03:40 --> 00:03:42 a thousand light years, okay, so you've got a
00:03:42 --> 00:03:45 sphere of radius a thousand light years,
00:03:45 --> 00:03:48 then that's going to have something like 10
00:03:49 --> 00:03:52 million stars in it. Whoa. So that's more
00:03:52 --> 00:03:54 than what uh, what um, Justin's
00:03:54 --> 00:03:57 talking about. Uh, but the way this
00:03:57 --> 00:04:00 changes, uh, it changes non linearly.
00:04:00 --> 00:04:03 Uh, so I'm guessing, so I'm going to take a
00:04:03 --> 00:04:05 guess that you know, around 9, 900
00:04:06 --> 00:04:08 light years or thereabouts, you
00:04:09 --> 00:04:12 would probably have something like 4 million
00:04:12 --> 00:04:14 stars, which is the same uh,
00:04:15 --> 00:04:17 mass as the mass of the supermassive uh,
00:04:18 --> 00:04:20 black hole at, of the galaxy. So it's
00:04:20 --> 00:04:22 actually quite a long way, you know, you're
00:04:22 --> 00:04:24 looking out. Yeah, several hundred light
00:04:24 --> 00:04:27 years. Uh, uh, in terms of
00:04:27 --> 00:04:30 radius. Uh, and
00:04:30 --> 00:04:32 um, it's actually I think you would
00:04:32 --> 00:04:35 probably be able to find a tool online. I
00:04:35 --> 00:04:37 haven't found it myself because I haven't
00:04:37 --> 00:04:38 really looked for it, but I bet you can find
00:04:38 --> 00:04:41 a tool that gives you the exact answer to
00:04:41 --> 00:04:43 that. Uh, how many stars are within a radius
00:04:43 --> 00:04:46 of X number of light years. And if you
00:04:46 --> 00:04:49 put in a good guess of light years, you'll
00:04:49 --> 00:04:51 probably get the right number of stars.
00:04:51 --> 00:04:52 Andrew Dunkley: Do you want me to test it?
00:04:53 --> 00:04:54 Professor Fred Watson: Yeah, if you can find one.
00:04:54 --> 00:04:56 Andrew Dunkley: Yeah. I've got an idea. So what's the
00:04:56 --> 00:04:59 question? How many stars
00:04:59 --> 00:05:02 in uh, say within
00:05:02 --> 00:05:03 900 light years?
00:05:04 --> 00:05:06 Professor Fred Watson: Okay, see what it is. This is a
00:05:06 --> 00:05:07 guess on my part.
00:05:07 --> 00:05:10 Andrew Dunkley: Uh, radius of
00:05:10 --> 00:05:11 900 light years.
00:05:13 --> 00:05:16 Okay, let's see what happens here.
00:05:17 --> 00:05:19 Um, I'll just make sure I ask the question
00:05:19 --> 00:05:20 correctly.
00:05:22 --> 00:05:25 Ah, nothing. Oh, here we go. Uh, uh,
00:05:26 --> 00:05:29 ah, it's saying 10 to
00:05:29 --> 00:05:29 15 million.
00:05:31 --> 00:05:33 Professor Fred Watson: Yeah. Um, which is different from the
00:05:33 --> 00:05:36 calculation I saw, which is 10 million in a
00:05:36 --> 00:05:38 thousand. So drop it down a bit. Can you put
00:05:38 --> 00:05:41 it down to 500 light years, see what it says
00:05:41 --> 00:05:43 for that. Okay. This is AI, I assume that
00:05:43 --> 00:05:46 is doing all this for you on
00:05:46 --> 00:05:47 Mr. Google.
00:05:47 --> 00:05:50 Andrew Dunkley: I absolutely love it. Um, two
00:05:50 --> 00:05:52 to two and a half million stars.
00:05:53 --> 00:05:55 Professor Fred Watson: Yeah. So it's somewhere between 500
00:05:55 --> 00:05:56 and 1 light years.
00:05:56 --> 00:05:57 Andrew Dunkley: There you go.
00:05:57 --> 00:05:59 Professor Fred Watson: So you put in whatever number you like, and
00:05:59 --> 00:06:02 it will give you the right answer. Uh, Justin
00:06:02 --> 00:06:03 can have a lot of fun doing that. It's a
00:06:03 --> 00:06:04 great question, actually.
00:06:04 --> 00:06:06 Andrew Dunkley: Just working out the averages. So
00:06:07 --> 00:06:10 750 light years transposes to
00:06:10 --> 00:06:12 7 to 8 million stars. So.
00:06:12 --> 00:06:13 Professor Fred Watson: Yeah.
00:06:13 --> 00:06:16 Andrew Dunkley: Yeah, there you go. You could
00:06:16 --> 00:06:17 do this all day, really.
00:06:20 --> 00:06:22 Professor Fred Watson: Um, I don't think we've ever been asked that
00:06:22 --> 00:06:22 before.
00:06:22 --> 00:06:23 Andrew Dunkley: No, I don't think so either.
00:06:23 --> 00:06:26 Professor Fred Watson: Not in that. That way. Um, we have had
00:06:26 --> 00:06:28 questions about, you know, the density. The
00:06:28 --> 00:06:30 average density of stars in the solar
00:06:30 --> 00:06:31 neighborhood, and that's really what this is
00:06:31 --> 00:06:31 all about.
00:06:32 --> 00:06:32 Andrew Dunkley: Yeah.
00:06:32 --> 00:06:35 Professor Fred Watson: Uh, but, uh, yeah, good stuff, Justin.
00:06:35 --> 00:06:37 Thank you for your question and greetings to
00:06:37 --> 00:06:39 Melbourne. It's 42 in Melbourne today, I
00:06:39 --> 00:06:39 think.
00:06:39 --> 00:06:42 Andrew Dunkley: Yes. Um, we've. We'. I've got 38 here
00:06:42 --> 00:06:43 today. I went and played golf in that this
00:06:43 --> 00:06:46 morning, and, uh, I was. What's the word I
00:06:46 --> 00:06:49 used? One of my friends used to use a lot
00:06:49 --> 00:06:51 when he was tired. I was jiggered by the end
00:06:51 --> 00:06:51 of it.
00:06:52 --> 00:06:52 Professor Fred Watson: That's a good.
00:06:53 --> 00:06:53 Andrew Dunkley: I don't know where it comes from.
00:06:53 --> 00:06:56 Professor Fred Watson: My granddad used to use that. Yeah, yeah.
00:06:56 --> 00:06:56 Justin: Ah.
00:06:56 --> 00:06:58 Professor Fred Watson: Uh, wheel it in. It's jiggered.
00:06:58 --> 00:07:01 Andrew Dunkley: Yeah, it was, uh. It was a tough day out, I
00:07:01 --> 00:07:03 must say. Uh, thanks, Justin.
00:07:03 --> 00:07:06 Our next question comes from Charles. Uh,
00:07:06 --> 00:07:08 but because I've been using, uh, ChatGPT
00:07:08 --> 00:07:11 to solve all the riddles of the universe,
00:07:11 --> 00:07:13 I've lost the question. All right. If
00:07:14 --> 00:07:17 the universe does cease expanding
00:07:17 --> 00:07:19 and retracts, does that mean the lifetime of
00:07:19 --> 00:07:22 the universe goes from, uh, untold
00:07:22 --> 00:07:25 trillion, beyond trillions of years
00:07:25 --> 00:07:28 or just a, um, measly few billion?
00:07:28 --> 00:07:31 This one comes from Charles in Brooklyn. In
00:07:31 --> 00:07:33 New York. I was in Brooklyn not so long ago.
00:07:33 --> 00:07:36 Walked across the Brooklyn Bridge. Yeah, in
00:07:36 --> 00:07:38 about August, it was m.
00:07:38 --> 00:07:40 Professor Fred Watson: Were you jiggered when you got to the end?
00:07:40 --> 00:07:42 Andrew Dunkley: I was jiggered before I started because we'd
00:07:42 --> 00:07:44 been walking all day.
00:07:46 --> 00:07:49 Professor Fred Watson: Yeah, I can imagine. Um, I think Charles
00:07:49 --> 00:07:52 is right, actually. Uh, look,
00:07:53 --> 00:07:54 it may still.
00:07:56 --> 00:07:59 I mean, the difference is really that
00:07:59 --> 00:08:02 if we have a universe which
00:08:02 --> 00:08:05 is dominated by a constant, uh,
00:08:05 --> 00:08:08 um, dark energy term. In other words,
00:08:08 --> 00:08:11 something that puts more energy into the
00:08:11 --> 00:08:14 expansion of space. As the expansion. As
00:08:14 --> 00:08:16 space gets bigger, uh, that means it will go
00:08:16 --> 00:08:19 on expanding forever. Um, so. And
00:08:19 --> 00:08:22 Charles has summarized that by untold
00:08:22 --> 00:08:24 trillions beyond trillions, which I guess is
00:08:24 --> 00:08:27 forever. Uh, but if the dark
00:08:27 --> 00:08:30 energy is reducing, and that's
00:08:30 --> 00:08:32 certainly being hinted at by the latest
00:08:32 --> 00:08:35 observations, then um,
00:08:35 --> 00:08:38 we don't know what's going to happen
00:08:38 --> 00:08:39 because we don't know how quickly it's
00:08:39 --> 00:08:42 reducing and whether it may even go negative.
00:08:43 --> 00:08:45 So that suddenly there's a positive
00:08:45 --> 00:08:47 attraction of stuff, it's not being repelled
00:08:47 --> 00:08:50 like it is now, that could bring it down to a
00:08:50 --> 00:08:53 few billion years. Uh, but if it just
00:08:53 --> 00:08:56 goes settles back to something where
00:08:56 --> 00:08:58 it's the normal gravitational content of the
00:08:58 --> 00:09:01 universe that dominates everything, uh, and
00:09:01 --> 00:09:02 so in other words all the galaxies are
00:09:02 --> 00:09:05 pulling each other together, uh, then
00:09:06 --> 00:09:07 you might be talking about a bit longer. It
00:09:07 --> 00:09:09 might still be a few trillion years rather
00:09:09 --> 00:09:12 than a few measly billions. Uh, but,
00:09:12 --> 00:09:14 ah, interesting question. A nice thought
00:09:14 --> 00:09:16 experiment there from Charles in Brooklyn.
00:09:16 --> 00:09:19 Andrew Dunkley: Yes, indeed. And as
00:09:19 --> 00:09:22 you said, the theory about like
00:09:22 --> 00:09:24 I think I've said it before, when I was
00:09:24 --> 00:09:26 growing up, it was always assumed that the
00:09:26 --> 00:09:28 universe would stop expanding and then start
00:09:29 --> 00:09:32 sort of folding back in on itself. Uh, the
00:09:32 --> 00:09:33 Big Crunch or the gnab.
00:09:33 --> 00:09:35 Professor Fred Watson: Gib, whatever you want to call it.
00:09:35 --> 00:09:38 Andrew Dunkley: But um, then it was decided
00:09:38 --> 00:09:40 that uh, it was going to continue expanding
00:09:40 --> 00:09:42 at an accelerating rate. Now they've decided
00:09:43 --> 00:09:45 and that could lead to a Big Rip. But now
00:09:45 --> 00:09:48 it's looking more like the acceleration
00:09:48 --> 00:09:51 is slowing and now
00:09:51 --> 00:09:53 all the bets are off and we're back to, back
00:09:53 --> 00:09:55 to square one or something. I'm not sure.
00:09:57 --> 00:10:00 Yeah. How do you prove it? Well, I mean
00:10:02 --> 00:10:05 you can measure that. What's going on?
00:10:05 --> 00:10:08 Professor Fred Watson: Yeah, and that's the trick. I mean
00:10:08 --> 00:10:10 if we'd been having this conversation a year
00:10:10 --> 00:10:13 ago, we'd have been completely sold on
00:10:13 --> 00:10:15 the Big Rip because there was nothing to
00:10:15 --> 00:10:18 suggest that the expansion was going to slow
00:10:18 --> 00:10:20 down. The expansion was known to be
00:10:20 --> 00:10:22 accelerating. That was discovered in 1998.
00:10:23 --> 00:10:25 Um, but it's only within the last year with
00:10:25 --> 00:10:28 um, results from project called desi,
00:10:28 --> 00:10:31 uh, the Dark Energy
00:10:31 --> 00:10:34 Survey Instrument I think is the right thing.
00:10:34 --> 00:10:37 Uh, but that's basically established
00:10:37 --> 00:10:40 that uh. Established is the wrong word. It
00:10:40 --> 00:10:42 has suggested that the acceleration
00:10:43 --> 00:10:45 is slower now than it was
00:10:46 --> 00:10:49 a couple of billion years ago. Uh, and
00:10:49 --> 00:10:51 that uh, is leading people
00:10:51 --> 00:10:54 to the hint that maybe the acceleration will
00:10:54 --> 00:10:57 eventually not be there. And that's why we
00:10:57 --> 00:10:59 might get the gnab Gib. But I think we're
00:10:59 --> 00:11:01 still talking about, I think, really think
00:11:01 --> 00:11:02 it's trillions of years into the future.
00:11:03 --> 00:11:05 Andrew Dunkley: It's m like blowing up a balloon though when
00:11:05 --> 00:11:08 you start it goes out fast, but as it gets
00:11:08 --> 00:11:11 bigger, uh, the expansion continues, but
00:11:11 --> 00:11:13 it just, it slows down. It's the same
00:11:13 --> 00:11:14 thing.
00:11:15 --> 00:11:16 Professor Fred Watson: Okay.
00:11:19 --> 00:11:22 Andrew Dunkley: Maybe not. It does remind me, um, we
00:11:22 --> 00:11:24 got a question in German the other day
00:11:24 --> 00:11:27 because apparently now what they're doing on
00:11:27 --> 00:11:29 YouTube Music, the people who listen to us on
00:11:29 --> 00:11:30 YouTube Music is, uh,
00:11:32 --> 00:11:35 English speaking. YouTube Music
00:11:35 --> 00:11:38 podcasts are being translated into other
00:11:38 --> 00:11:41 languages. So apparently we were
00:11:41 --> 00:11:43 being heard in German, and a German listener
00:11:43 --> 00:11:46 on YouTube Music sent us a question in
00:11:46 --> 00:11:49 German and we had to translate
00:11:49 --> 00:11:52 it into English so that we knew what he was
00:11:52 --> 00:11:54 asking. But I don't think it translated very
00:11:54 --> 00:11:56 well. But it was something about, how do you
00:11:56 --> 00:11:59 prove the expansion of the universe
00:11:59 --> 00:12:02 if you haven't found a particle?
00:12:02 --> 00:12:05 Professor Fred Watson: Well, I wasn't sure whether I did look at
00:12:05 --> 00:12:07 that question. In fact, I did send an answer
00:12:07 --> 00:12:09 which I think, um, Huw might have put through
00:12:09 --> 00:12:12 some language mangling, um,
00:12:12 --> 00:12:14 system to give the answer in German.
00:12:15 --> 00:12:16 Uh, mein Deutsch is
00:12:17 --> 00:12:20 crap. Uh, so, um,
00:12:21 --> 00:12:24 that's K R A double P. It's
00:12:24 --> 00:12:27 not, uh,
00:12:28 --> 00:12:30 uh, so, um, I think. I wasn't sure
00:12:30 --> 00:12:33 whether it was somebody talking about dark
00:12:33 --> 00:12:35 energy or dark matter. Yeah, I wasn't sure
00:12:35 --> 00:12:38 either. But dark matter, yes, we do need to
00:12:38 --> 00:12:41 know what the particles are. And, um, I hope
00:12:41 --> 00:12:43 we'll discover them. I. I'm not optimistic.
00:12:43 --> 00:12:45 M. We're going to find that out during 2026,
00:12:45 --> 00:12:46 but you never know.
00:12:46 --> 00:12:49 Andrew Dunkley: Anything's possible. Thanks for your
00:12:49 --> 00:12:50 question, Charles.
00:12:50 --> 00:12:52 This is Space Nuts, uh, Q and A edition with
00:12:52 --> 00:12:54 Andrew Dunkley and Fred Watson.
00:12:56 --> 00:12:58 Andrew Dunkley: Now, let's take a break from the show to tell
00:12:58 --> 00:13:00 you about our, uh, sponsor, uh, NordVPN. Now,
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00:14:21 --> 00:14:24 1. Space
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00:14:25 --> 00:14:28 Andrew Dunkley: Uh, next up we've got Dean who's got
00:14:28 --> 00:14:30 a kind of a what if question for. I love
00:14:30 --> 00:14:33 these, Fred. These are my favourite
00:14:33 --> 00:14:34 questions. What if this happens?
00:14:34 --> 00:14:37 Andrew Dunkley: Hi Fred and Andrew, this is Dean in Redcliffe
00:14:37 --> 00:14:39 in Queensland. Thanks for answering my
00:14:39 --> 00:14:42 previous questions. Today I'm asking about
00:14:42 --> 00:14:44 a thought experiment that was once used to
00:14:44 --> 00:14:46 consider issues around the speed of light. I
00:14:46 --> 00:14:49 think it may have been Einstein. The scenario
00:14:49 --> 00:14:51 asks what happens if our uh, sun suddenly
00:14:51 --> 00:14:54 disappears and would the sudden lack of
00:14:54 --> 00:14:56 gravity affect the earth instantly or would
00:14:56 --> 00:14:59 there be a delay if the gravity effect
00:14:59 --> 00:15:02 travels at a particular speed? Before
00:15:02 --> 00:15:03 I get to my actual question, I want to ask
00:15:03 --> 00:15:06 about thought experiments. They seem like a
00:15:06 --> 00:15:08 useful tool to get started on a problem, but
00:15:08 --> 00:15:11 I question the value of an experiment where
00:15:11 --> 00:15:13 the uh, initial proposition is impossible.
00:15:14 --> 00:15:16 The mass of the sun can't actually just
00:15:16 --> 00:15:19 disappear. So maybe basing conclusions
00:15:19 --> 00:15:21 from this is not reliable. What are your
00:15:21 --> 00:15:24 thoughts? However, if I just focus on the
00:15:24 --> 00:15:26 idea of the sun disappearing, I'd say that
00:15:26 --> 00:15:29 gravity is not a force generated by the sun,
00:15:29 --> 00:15:31 but is a compression of the spacetime around
00:15:31 --> 00:15:34 it. If the sun disappeared
00:15:34 --> 00:15:37 instantly, then space time would decompress
00:15:37 --> 00:15:40 back to a smooth state, except for the
00:15:40 --> 00:15:42 planets and moons still in the vicinity.
00:15:42 --> 00:15:44 There would also have to be an unwinding of
00:15:44 --> 00:15:47 the frame dragging around where the sun was.
00:15:47 --> 00:15:49 Let me know if I'm wrong, but it seems to me
00:15:50 --> 00:15:52 that a sudden decompression and unwinding of
00:15:52 --> 00:15:54 some local space time would be violent but
00:15:54 --> 00:15:56 uh, would not be instant.
00:15:57 --> 00:16:00 Imagine the 2D model of this using
00:16:00 --> 00:16:02 a large rubber sheet with a heavy ball in the
00:16:02 --> 00:16:05 center representing the sun. If you suddenly
00:16:05 --> 00:16:08 removed the ball, then the warped sheet would
00:16:08 --> 00:16:11 snap back into a flat plane quickly,
00:16:11 --> 00:16:12 but not instantly.
00:16:13 --> 00:16:16 Spacetime is very stiff. Maybe the Earth
00:16:16 --> 00:16:19 would start to feel some effect very
00:16:19 --> 00:16:21 quickly, but there would be a smooth
00:16:21 --> 00:16:24 transition to the complete lack of
00:16:24 --> 00:16:26 sun's gravity while the local spacetime is
00:16:26 --> 00:16:29 settling into a decompressed state.
00:16:29 --> 00:16:31 I also expect there would be a compression
00:16:31 --> 00:16:34 wave that is a uh, gravity wave generated
00:16:34 --> 00:16:37 from an event like this. What do you think?
00:16:39 --> 00:16:41 Andrew Dunkley: There's a lot packaged into that. Thank, uh,
00:16:41 --> 00:16:42 you Dean.
00:16:42 --> 00:16:45 Uh, so there's a question or two questions
00:16:45 --> 00:16:47 effectively uh, that he's asking about,
00:16:48 --> 00:16:50 um, what's the worth of thought
00:16:50 --> 00:16:52 experiments? Uh, now
00:16:54 --> 00:16:57 yeah, I did
00:16:57 --> 00:16:58 a Little bit of research while I was
00:16:58 --> 00:17:01 listening to him. And to give you an idea of
00:17:01 --> 00:17:03 thought experiments, um, there have been many
00:17:03 --> 00:17:05 famous ones over the years. Schrodinger's
00:17:05 --> 00:17:08 cat, Galileo's, uh, falling
00:17:08 --> 00:17:11 bodies. Um, there's
00:17:11 --> 00:17:13 one called the Trolley Problem. I have to
00:17:13 --> 00:17:15 look into that. Don't know what that one is.
00:17:15 --> 00:17:17 But, um, yeah, they have been very
00:17:17 --> 00:17:20 helpful over the years. I do think there is
00:17:20 --> 00:17:23 worth in thought experiments. It's a
00:17:23 --> 00:17:25 way of exploring something that we can't
00:17:25 --> 00:17:26 solve yet because we haven't got the
00:17:26 --> 00:17:29 technology to solve it. But it
00:17:29 --> 00:17:31 gives you something to work with and it
00:17:31 --> 00:17:34 tosses around ideas that may provide
00:17:34 --> 00:17:37 solutions. It's, um. I think.
00:17:38 --> 00:17:40 I love the concept. I think it's very
00:17:40 --> 00:17:43 valuable. It's how we start making
00:17:43 --> 00:17:45 inquiries with thought experiments.
00:17:46 --> 00:17:48 If we didn't use our imaginations, then we
00:17:48 --> 00:17:50 probably wouldn't solve anything.
00:17:50 --> 00:17:53 Professor Fred Watson: Exactly. Um, a great answer, actually.
00:17:53 --> 00:17:56 Andrew. Thank you. Um, I'll. I'll just
00:17:56 --> 00:17:59 go home and. No,
00:17:59 --> 00:18:02 I entirely agree. Um, the one that came to my
00:18:02 --> 00:18:05 mind was a thought experiment that, had the
00:18:05 --> 00:18:07 real experiment been carried out, physics,
00:18:07 --> 00:18:09 uh, would have ground to a halt very quickly.
00:18:09 --> 00:18:12 And that's, uh, Einstein's
00:18:12 --> 00:18:14 musing in 1907
00:18:15 --> 00:18:17 about what would happen if he jumped off the
00:18:17 --> 00:18:20 top of the Patents Building in Berne, which
00:18:20 --> 00:18:22 is where he was working at the time. He was a
00:18:22 --> 00:18:25 patent administrator. Uh, and so
00:18:25 --> 00:18:26 he imagined himself jumping off the top of
00:18:26 --> 00:18:29 the building. Uh, so if he carried that out
00:18:29 --> 00:18:30 as a real experiment, that could have been
00:18:30 --> 00:18:33 the end of a lot of really good stuff. Yeah.
00:18:34 --> 00:18:36 Uh, but what it gave him was the inspiration
00:18:37 --> 00:18:40 to, um, define what we now call the
00:18:40 --> 00:18:42 principle of equivalence. The fact that
00:18:42 --> 00:18:45 acceleration and gravity are, uh,
00:18:45 --> 00:18:48 to all intents and purposes, the same. Um,
00:18:49 --> 00:18:51 so. And the fact that you're accelerating
00:18:51 --> 00:18:54 towards the Earth, uh, cancels out the
00:18:54 --> 00:18:56 Earth's gravity because the two are exactly
00:18:56 --> 00:18:57 equal. And that's why
00:18:59 --> 00:19:01 as you jump off the building, uh, your pipe
00:19:01 --> 00:19:03 floats out of your mouth. If you've got money
00:19:03 --> 00:19:05 in your hands or something like that, it just
00:19:05 --> 00:19:07 floats away. You can actually demonstrate it
00:19:07 --> 00:19:09 very easily on a trampoline, uh, without
00:19:09 --> 00:19:11 jumping off buildings. But it was that
00:19:11 --> 00:19:13 thought experiment that led to the principle
00:19:13 --> 00:19:16 of equivalence, which told Einstein that
00:19:16 --> 00:19:18 gravity is actually a geometrical problem
00:19:19 --> 00:19:22 rather than, you know, something entwined
00:19:22 --> 00:19:24 in physics. We know it is. We still don't
00:19:24 --> 00:19:26 really understand the physics of gravity, but
00:19:26 --> 00:19:29 the geometry works so well. Well, uh,
00:19:29 --> 00:19:32 in the general, uh, theory of relativity
00:19:32 --> 00:19:34 that, um, the principle of equivalence has
00:19:34 --> 00:19:37 been demonstrated to be accurate to within
00:19:37 --> 00:19:39 one part, uh, in 10 to the 18 or something. I
00:19:39 --> 00:19:42 can't remember what the latest thing is, uh,
00:19:42 --> 00:19:45 that it does work very, very well indeed. Uh,
00:19:45 --> 00:19:47 so yes, thought experiments are great. Um,
00:19:47 --> 00:19:49 now the thought experiment regarding taking
00:19:49 --> 00:19:51 the sun out the solar system is very well
00:19:51 --> 00:19:54 established as to what happens. Uh,
00:19:55 --> 00:19:57 the Earth feels nothing for the first eight
00:19:57 --> 00:20:00 minutes, uh, because gravitational energy
00:20:00 --> 00:20:02 travels at the same speed as light. Uh,
00:20:02 --> 00:20:05 and once, um, the message
00:20:05 --> 00:20:08 that there is no gravitating body
00:20:08 --> 00:20:11 in the center of the solar system reaches the
00:20:11 --> 00:20:13 Earth eight minutes after the sun has gone,
00:20:13 --> 00:20:15 um, the Earth just carries on in a straight
00:20:15 --> 00:20:18 line. Uh, ah,
00:20:18 --> 00:20:21 so, uh, that's well understood. So,
00:20:22 --> 00:20:25 um, I think, uh, um,
00:20:25 --> 00:20:27 Dean's um, thinking uh, about
00:20:28 --> 00:20:30 the, you know, the, the two dimensional
00:20:30 --> 00:20:33 idea of the gravity well, uh, which is a
00:20:33 --> 00:20:35 great way of thinking of the way, uh, mass
00:20:35 --> 00:20:38 distorts time. Uh, we're used to
00:20:38 --> 00:20:41 thinking, okay, you've got a rock in the
00:20:41 --> 00:20:43 middle of a trampoline. It's pulling it down,
00:20:43 --> 00:20:45 you take the rock away, the trampoline just
00:20:45 --> 00:20:47 springs back. Uh, but actually, uh, it
00:20:47 --> 00:20:50 wouldn't. The space time would take, uh,
00:20:50 --> 00:20:53 time, uh, basically the message that
00:20:53 --> 00:20:56 it had sprung back would take, would travel
00:20:56 --> 00:20:58 outwards at the speed of light. Uh, and so
00:20:58 --> 00:21:00 it's the same, you know, the same thing
00:21:00 --> 00:21:03 looking at it either as a gravity well or
00:21:03 --> 00:21:05 as gravitational energy or radiation.
00:21:06 --> 00:21:07 One day we'll have a quantum theory of
00:21:07 --> 00:21:09 gravity and we'll be able to talk about
00:21:09 --> 00:21:11 gravitons, uh, which are, uh, the
00:21:11 --> 00:21:13 hypothetical particles that carry gravity and
00:21:13 --> 00:21:14 they move at the speed of light.
00:21:15 --> 00:21:17 Andrew Dunkley: Of course, we should mention the catastrophe
00:21:17 --> 00:21:19 that would then follow 8 minutes after the
00:21:19 --> 00:21:22 sun suddenly disappeared. 4 example.
00:21:22 --> 00:21:25 Pavlov's dog and Schroding's Schrodinger's
00:21:25 --> 00:21:25 cat would live together.
00:21:26 --> 00:21:29 Professor Fred Watson: Yes. So they would.
00:21:30 --> 00:21:33 Yeah. Oh, deary me. Uh, that's. Yes.
00:21:34 --> 00:21:37 Andrew Dunkley: Would be a mess. How long would the
00:21:37 --> 00:21:39 Earth last after that effect?
00:21:39 --> 00:21:41 Professor Fred Watson: Uh, it would be fine. It would just keep on
00:21:41 --> 00:21:43 going. Um, you know, assuming there wasn't
00:21:43 --> 00:21:45 some sort of, um, uh,
00:21:45 --> 00:21:47 catastrophic event that caused the sun to
00:21:47 --> 00:21:50 disappear. If you just remove the sun without
00:21:50 --> 00:21:53 anything, explodes anything, which you can do
00:21:53 --> 00:21:55 in a thought experiment, the Earth just
00:21:55 --> 00:21:57 keeps, keeps on going. It will be like
00:21:57 --> 00:21:59 Voyager 1 and Voyager 2. It will get very,
00:21:59 --> 00:22:02 very cold. Uh, we as a species will almost
00:22:02 --> 00:22:04 certainly not survive, uh, because the
00:22:04 --> 00:22:06 temperatures would plummet to very low levels
00:22:06 --> 00:22:09 indeed. Um, so yes, uh,
00:22:09 --> 00:22:11 an interesting scenario.
00:22:11 --> 00:22:13 Andrew Dunkley: Doesn't sound like much fun.
00:22:13 --> 00:22:13 Professor Fred Watson: It's not fun.
00:22:13 --> 00:22:14 Andrew Dunkley: No. No.
00:22:14 --> 00:22:16 Professor Fred Watson: Anyway, think about it though.
00:22:16 --> 00:22:19 Andrew Dunkley: We're stuck with um, with the
00:22:19 --> 00:22:21 sun for Several more billion years.
00:22:22 --> 00:22:23 Professor Fred Watson: Yes, indeed we are.
00:22:25 --> 00:22:27 Andrew Dunkley: But, uh, great questions, Dean. I really
00:22:27 --> 00:22:30 enjoy those kinds of questions. So, uh,
00:22:30 --> 00:22:31 yeah, thanks for sending it in.
00:22:33 --> 00:22:34 Let's take a break from the show.
00:22:34 --> 00:22:36 Andrew Dunkley: To tell you about our, uh, sponsor, uh, anti
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00:24:00 --> 00:24:02 Andrew Dunkley: 3, 2, 1.
00:24:03 --> 00:24:04 Andrew Dunkley: Space nuts.
00:24:05 --> 00:24:08 Andrew Dunkley: Our, uh, final question today comes from
00:24:08 --> 00:24:10 Patrick. He's a conspiracy theorist. Well,
00:24:10 --> 00:24:12 he's probably not, but I do like this
00:24:12 --> 00:24:14 question because I, I didn't know this.
00:24:15 --> 00:24:17 Uh, the Voyager spacecraft have plaques on
00:24:17 --> 00:24:20 them. I did know that. And as far as I can
00:24:20 --> 00:24:23 find out, both show them leaving the solar
00:24:23 --> 00:24:25 system ecliptic, um, between
00:24:25 --> 00:24:28 Jupiter and Saturn. That didn't happen.
00:24:29 --> 00:24:32 And from what I've read, Voyager 1 left after
00:24:32 --> 00:24:34 a visit to Titan while Voyager, uh, 2
00:24:34 --> 00:24:37 carried on. Uh, Voyager 1,
00:24:38 --> 00:24:41 uh, had a chance to visit Pluto. So his the
00:24:41 --> 00:24:44 questions. Why does the plaque show an early
00:24:44 --> 00:24:46 departure of Voyager 1? And why does Voyager
00:24:46 --> 00:24:49 2's path show the same? Um,
00:24:49 --> 00:24:52 hope you both had a wonderful Christmas and
00:24:52 --> 00:24:55 um, hello from a wet northern island.
00:24:56 --> 00:24:59 Patrick. Wet Northern Ireland. It's probably
00:24:59 --> 00:25:01 still wet, just like we're still dry.
00:25:02 --> 00:25:04 We've hit the hottest, driest part of the
00:25:04 --> 00:25:07 year in Australia and, um, it is dry as a
00:25:07 --> 00:25:09 chip, as we say in this country
00:25:10 --> 00:25:12 at the moment. Um, yeah,
00:25:12 --> 00:25:15 okay. I didn't realize that the plaques had
00:25:15 --> 00:25:17 the supposed path of both
00:25:17 --> 00:25:20 spacecraft, but they didn't go that way. Did
00:25:20 --> 00:25:22 they get pulled over by an RBT Perhaps.
00:25:24 --> 00:25:27 Professor Fred Watson: Um, I thought you'd have spotted this one
00:25:27 --> 00:25:29 right at the start, Andrew.
00:25:29 --> 00:25:32 Andrew Dunkley: Really? Is he
00:25:32 --> 00:25:33 playing us?
00:25:33 --> 00:25:36 Professor Fred Watson: Uh, no, he's got his spacecraft mixed up.
00:25:36 --> 00:25:39 Because it's the two, the two pioneers
00:25:39 --> 00:25:42 that show the spacecraft leaving the solar
00:25:42 --> 00:25:45 system between orbits of Jupiter.
00:25:45 --> 00:25:46 Andrew Dunkley: I never even thought of that.
00:25:47 --> 00:25:50 Professor Fred Watson: Voyager doesn't actually have a diagram like
00:25:50 --> 00:25:52 that on it. It's got mostly diagrams how to
00:25:52 --> 00:25:53 play the Golden Record.
00:25:53 --> 00:25:54 Andrew Dunkley: That's right.
00:25:54 --> 00:25:57 Professor Fred Watson: Um, so it's the Pioneer spacecraft. So
00:25:57 --> 00:26:00 Patrick, you, your, your question's a good
00:26:00 --> 00:26:03 one, but I think the premise is
00:26:03 --> 00:26:05 wrong. It's not the Voyager spacecraft that
00:26:05 --> 00:26:06 had the diagram, it's the pioneers.
00:26:06 --> 00:26:09 Andrew Dunkley: Well, how about that? Yeah, I'm
00:26:09 --> 00:26:11 just looking at them now. Okay.
00:26:13 --> 00:26:15 That's really. And it's got the human
00:26:15 --> 00:26:16 being on it.
00:26:17 --> 00:26:19 Professor Fred Watson: I actually really like the Pioneer, uh,
00:26:19 --> 00:26:21 plaques. I think they're elegant and
00:26:21 --> 00:26:24 decorative and tell, um, the story.
00:26:24 --> 00:26:26 Just show aliens just how
00:26:27 --> 00:26:28 chewy we are and you know.
00:26:28 --> 00:26:29 Andrew Dunkley: Yeah.
00:26:29 --> 00:26:31 Professor Fred Watson: How tasty we might be and how.
00:26:31 --> 00:26:34 Andrew Dunkley: Um, unfortunate that male appendage is.
00:26:34 --> 00:26:36 It's well below par, but.
00:26:38 --> 00:26:40 And the other factor is that.
00:26:41 --> 00:26:42 Professor Fred Watson: Thanks, Andrew.
00:26:42 --> 00:26:44 Andrew Dunkley: Aliens will look at these two human figures
00:26:44 --> 00:26:47 and they'll go, she does
00:26:47 --> 00:26:48 not like him.
00:26:50 --> 00:26:51 Professor Fred Watson: That's right.
00:26:51 --> 00:26:53 Andrew Dunkley: The body language is not positive.
00:26:53 --> 00:26:56 Professor Fred Watson: That's true. There is body language on there
00:26:56 --> 00:26:58 that really. Yeah, I'm with you on M. That
00:26:58 --> 00:27:01 actually. It's all about
00:27:01 --> 00:27:03 body language. Yeah.
00:27:03 --> 00:27:05 Andrew Dunkley: So now I'm going to have to look up what the
00:27:05 --> 00:27:07 Voyager plaques look like.
00:27:07 --> 00:27:08 Professor Fred Watson: Yeah. Ah, ah.
00:27:08 --> 00:27:11 Andrew Dunkley: See, it's. Yes. The Golden Record with the,
00:27:11 --> 00:27:14 um, bits and bobs on the stuff on
00:27:14 --> 00:27:16 it. Yeah, yeah. Okay.
00:27:17 --> 00:27:20 So, um, right idea. Wrong.
00:27:20 --> 00:27:22 Wrong spacecraft is basically the answer to
00:27:22 --> 00:27:23 the question.
00:27:24 --> 00:27:25 Professor Fred Watson: Uh, I think that's correct.
00:27:27 --> 00:27:30 Andrew Dunkley: Um, I think we can safely say that Voyager 1
00:27:30 --> 00:27:32 and Voyager 2 did go where we intended them
00:27:32 --> 00:27:35 to go. And they're still going.
00:27:35 --> 00:27:37 Professor Fred Watson: Yeah, indeed they are. Voyager 2, well,
00:27:37 --> 00:27:39 Pioneer 10 and 11 are as well. Uh, Voyager
00:27:39 --> 00:27:42 2 was the one that flew by Uranus, uh, and
00:27:42 --> 00:27:44 Neptune as well as Jupiter and Saturn.
00:27:44 --> 00:27:47 Fantastic details that came from those two
00:27:47 --> 00:27:50 spacecraft. Voyager 1, as we've said many
00:27:50 --> 00:27:53 times before, is the most distant human
00:27:53 --> 00:27:56 made object and is still on
00:27:56 --> 00:27:58 its way. It's almost a light day away. We
00:27:58 --> 00:28:00 should have a little party at Space Nuts when
00:28:00 --> 00:28:03 it crosses a light day. Um, the light
00:28:03 --> 00:28:04 day boundary. Yeah.
00:28:04 --> 00:28:07 Andrew Dunkley: Which, uh, is happening in about 500 years
00:28:07 --> 00:28:10 from now. No, I'm not sure. It can't be that
00:28:10 --> 00:28:10 far away.
00:28:10 --> 00:28:12 Professor Fred Watson: Yeah, it's a few years. Yeah, a couple of
00:28:12 --> 00:28:14 years. I think it's about 23 light hours at
00:28:14 --> 00:28:17 the moment. Uh, so it'll be. Yes. Four or
00:28:17 --> 00:28:17 five years.
00:28:18 --> 00:28:20 Andrew Dunkley: Yeah. Wow. Yeah, we thought we should do
00:28:20 --> 00:28:21 something special about that.
00:28:22 --> 00:28:22 Professor Fred Watson: Yes.
00:28:22 --> 00:28:25 Andrew Dunkley: M. All right. Um, well, that was easily
00:28:25 --> 00:28:26 solved. Thanks for the question, though. Uh,
00:28:26 --> 00:28:29 Patrick. It sort of. Yeah, it reminds us
00:28:29 --> 00:28:31 that, uh, as time goes on, you can sort of
00:28:31 --> 00:28:34 mix two totally different things
00:28:34 --> 00:28:35 together and.
00:28:36 --> 00:28:38 Yeah, it throws. Throws your brain out.
00:28:39 --> 00:28:42 Um, it reminds me of a story once where,
00:28:42 --> 00:28:45 um. Oh, gosh, a guy I
00:28:45 --> 00:28:47 worked with in radio did a special about,
00:28:47 --> 00:28:50 um, uh, Dean Martin and
00:28:50 --> 00:28:52 Jerry Lewis getting back together. Remember
00:28:52 --> 00:28:52 them?
00:28:52 --> 00:28:53 Professor Fred Watson: Yeah.
00:28:53 --> 00:28:56 Andrew Dunkley: Yeah, but he thought it was Jerry Lee Lewis,
00:28:57 --> 00:28:59 so he did this whole special with Jerry Lee
00:28:59 --> 00:29:00 Lewis music.
00:29:02 --> 00:29:05 Completely wrong. Yes, but it can
00:29:05 --> 00:29:05 happen.
00:29:06 --> 00:29:08 Professor Fred Watson: It can happen. Yeah, I, um.
00:29:09 --> 00:29:11 Yes, I looked at some research recently where
00:29:11 --> 00:29:14 they'd got the wrong telescope. Uh,
00:29:14 --> 00:29:15 yeah, well, it's like getting the.
00:29:15 --> 00:29:17 Andrew Dunkley: Color of the universe wrong when you make.
00:29:17 --> 00:29:19 Professor Fred Watson: That's another one. That's correct. Yes.
00:29:19 --> 00:29:19 Yeah.
00:29:20 --> 00:29:23 Andrew Dunkley: Oh, there's a list of them. There's a list of
00:29:23 --> 00:29:25 them. So don't feel bad, Patrick. It happens
00:29:25 --> 00:29:27 to the best of us. Uh, but thanks for the
00:29:27 --> 00:29:29 question. Lovely to hear from you. If you've
00:29:29 --> 00:29:31 got questions for us, please send them in to
00:29:31 --> 00:29:33 us via our website. Just go to
00:29:33 --> 00:29:36 spacenutspodcast.com or
00:29:36 --> 00:29:39 spacenuts IO if you're a lazy
00:29:39 --> 00:29:42 typist, and click on the AMA
00:29:42 --> 00:29:44 button up the top, and, uh, you can send us
00:29:44 --> 00:29:46 text and audio questions that away.
00:29:47 --> 00:29:48 Uh, we sometimes get them through
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00:29:50 --> 00:29:52 listener, please, uh, send them in. Be, um,
00:29:52 --> 00:29:55 happy to hear from you. Uh, and don't forget
00:29:55 --> 00:29:57 reviews. We. We really appreciate your
00:29:57 --> 00:30:00 reviews. The more reviews, the better. I, um,
00:30:00 --> 00:30:03 mean, it's an astronomy podcast, so,
00:30:03 --> 00:30:06 you know, um, five stars would be the
00:30:06 --> 00:30:09 absolute minimum I would expect. That's up
00:30:09 --> 00:30:12 to you. No influence here. No influence
00:30:12 --> 00:30:12 here.
00:30:12 --> 00:30:13 Professor Fred Watson: Four million stars.
00:30:13 --> 00:30:15 Andrew Dunkley: Four million stars. Yes. Deal.
00:30:16 --> 00:30:18 Uh, and, um, yeah, if you'd like to do that
00:30:18 --> 00:30:20 for us, that'd be great. And don't forget to,
00:30:20 --> 00:30:23 um, check out our website if, uh, you. To,
00:30:23 --> 00:30:26 uh, support us. Some people do through, um,
00:30:26 --> 00:30:29 Patreon and Supercast. Uh, there's
00:30:29 --> 00:30:32 a little button where it says, support our
00:30:32 --> 00:30:34 podcasts. So click that button, you can find
00:30:34 --> 00:30:36 out more about it. It's totally voluntary.
00:30:37 --> 00:30:39 Um, Fred, we are done. Thank you so much for
00:30:39 --> 00:30:40 answering those questions.
00:30:40 --> 00:30:42 Professor Fred Watson: Oh, uh, it's a pleasure. It's, um, always
00:30:42 --> 00:30:44 good to interact with our, uh, four
00:30:44 --> 00:30:47 listeners. Yes, we've
00:30:47 --> 00:30:49 only got four at a time.
00:30:50 --> 00:30:53 Yeah, no, it's good. And thank you very much.
00:30:53 --> 00:30:55 Uh, again, as always, Andre, for being the
00:30:55 --> 00:30:56 host of Space Notes.
00:30:56 --> 00:30:58 Andrew Dunkley: Oh, my great pleasure. It's good fun,
00:30:59 --> 00:31:00 Professor, Uh, Fred Watson, astronomer at
00:31:00 --> 00:31:02 large. He'll join us again on the next
00:31:02 --> 00:31:04 episode. Uh, and Huw in the studio couldn't
00:31:04 --> 00:31:06 be with us today because he was doing a
00:31:06 --> 00:31:09 thought experiment, uh, where
00:31:09 --> 00:31:10 he didn't exist.
00:31:13 --> 00:31:16 What more can I say? Uh, and from me, Andrew
00:31:16 --> 00:31:17 Dunkley, thanks for your company. We'll catch
00:31:17 --> 00:31:19 you on the next episode of Space Nuts. Bye.
00:31:19 --> 00:31:21 Bye. Space Nuts.
00:31:21 --> 00:31:23 Andrew Dunkley: You've been listening to the Space Nuts
00:31:23 --> 00:31:25 podcast, available
00:31:26 --> 00:31:28 at Apple Podcasts, Spotify,
00:31:28 --> 00:31:31 iHeartRadio, or your favorite podcast
00:31:31 --> 00:31:33 player. You can also stream on demand at
00:31:33 --> 00:31:34 bytes.
00:31:34 --> 00:31:34 Professor Fred Watson: Com.
00:31:34 --> 00:31:37 Andrew Dunkley: Um, this has been another quality podcast
00:31:37 --> 00:31:38 production from Bytes.
00:31:38 --> 00:31:38 Professor Fred Watson: Com.
00:31:38 --> 00:31:39 Andrew Dunkley: Um.