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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. (https://www.spacenutspodcast.com/) 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.
If you’d like to help support Space Nuts and join our growing family of insiders for commercial-free episodes and more, visit spacenutspodcast.com/about (https://www.spacenutspodcast.com/about) .
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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Episode link: https://play.headliner.app/episode/31068653?utm_source=youtube
00:00:00 --> 00:00:02 Hi there. Thanks for joining us on a Q&A
00:00:02 --> 00:00:04 edition of Space Nuts, our first one for
00:00:04 --> 00:00:07 the year. My name is Andrew Dunley, your
00:00:07 --> 00:00:09 host. And we've got questions from
00:00:09 --> 00:00:12 Justin, who's um got a sent us an audio
00:00:12 --> 00:00:15 question. Um he he's talking about the
00:00:15 --> 00:00:18 space that contains the equivalent to 4
00:00:18 --> 00:00:20 million stars in comparison to a black
00:00:20 --> 00:00:23 hole, I think. Can't remember. I I don't
00:00:23 --> 00:00:24 write down enough when I write down the
00:00:24 --> 00:00:28 descriptions of questions. Uh Charles,
00:00:28 --> 00:00:29 >> you're right.
00:00:29 --> 00:00:31 >> Fred's Fred's saying the same thing. Uh
00:00:32 --> 00:00:35 Charles says um is asking us a question
00:00:35 --> 00:00:38 about the retraction of uh the universe,
00:00:38 --> 00:00:41 the shrinking of it. Uh and Dean is
00:00:41 --> 00:00:44 asking about what might happen if the
00:00:44 --> 00:00:46 sun instantaneously disappeared. What
00:00:46 --> 00:00:49 would be the effect on our solar system
00:00:49 --> 00:00:51 and our planet specifically? And Patrick
00:00:52 --> 00:00:54 has some thoughts about uh both the
00:00:54 --> 00:00:57 Voyagers one and two. Mainly the fact
00:00:57 --> 00:00:59 that the data we've put on the plaques
00:00:59 --> 00:01:02 that have been put on board the Voyagers
00:01:02 --> 00:01:04 is actually telling anyone who finds
00:01:04 --> 00:01:07 them a lie. That's all coming up in this
00:01:07 --> 00:01:10 edition of Space Muts. And with us once
00:01:10 --> 00:01:13 again to decipher all of that gibberish
00:01:13 --> 00:01:15 that I just mentioned, and it's not the
00:01:16 --> 00:01:17 questions that are gibberish, it's my
00:01:17 --> 00:01:19 interpretation of them, is Professor
00:01:19 --> 00:01:21 Fred Watson, astronomer at large. Hello,
00:01:21 --> 00:01:22 Fred.
00:01:22 --> 00:01:25 >> Hi, Andrew. Your interpretation was more
00:01:25 --> 00:01:26 or less the same as what I thought when
00:01:26 --> 00:01:29 I saw them. So, I think we're on the
00:01:29 --> 00:01:30 same wavelength, which is good.
00:01:30 --> 00:01:33 >> Okay. Okay. Well, that's good. Uh, we
00:01:33 --> 00:01:35 might as well just hit them straight on
00:01:35 --> 00:01:37 the head. And our first question is an
00:01:37 --> 00:01:39 audio question and this one comes from
00:01:39 --> 00:01:40 Justin.
00:01:40 --> 00:01:42 >> Good day Andrew and Fred. I'm Justin
00:01:42 --> 00:01:45 down in Melbourne. Like Fred, I'm an
00:01:45 --> 00:01:48 expat pong and my astronomical claim to
00:01:48 --> 00:01:51 fame is that I witnessed the total solar
00:01:51 --> 00:01:55 eclipse in Cornwall in the UK in 1999.
00:01:55 --> 00:01:57 Two friends and I camped nearby and
00:01:57 --> 00:02:00 joined the crowds at New Key Beach on
00:02:00 --> 00:02:02 that day for a lifetime bucket list
00:02:02 --> 00:02:04 event.
00:02:04 --> 00:02:07 So, I have a mathematical question. I've
00:02:07 --> 00:02:08 often heard it said that the black hole
00:02:08 --> 00:02:10 at the center of the Milky Way galaxy,
00:02:10 --> 00:02:14 Sagittarius A star, is 4 million solar
00:02:14 --> 00:02:17 masses. So, for comparison, what would
00:02:18 --> 00:02:21 the radius be in light years of a sphere
00:02:21 --> 00:02:23 centered on the Earth that contains the
00:02:23 --> 00:02:26 nearest 4 million stars?
00:02:26 --> 00:02:28 Thanks very much.
00:02:28 --> 00:02:30 >> Thank you, Justin Cornwall. That's where
00:02:30 --> 00:02:33 my family originated
00:02:33 --> 00:02:35 before they um they got sent out here.
00:02:36 --> 00:02:38 No, I think they came voluntarily.
00:02:38 --> 00:02:40 We we didn't come with the convicts. We
00:02:40 --> 00:02:43 we came out later. But um yeah, Justin,
00:02:43 --> 00:02:46 good question. 4 million stars. Um what
00:02:46 --> 00:02:48 sort of space would that take up in
00:02:48 --> 00:02:50 terms of a radius in light years, I
00:02:50 --> 00:02:52 think, was the the guts of his question.
00:02:52 --> 00:02:55 >> Yeah. So, it's a a little bit more
00:02:55 --> 00:02:57 subtle than that. It's saying I figured
00:02:57 --> 00:02:58 it might be
00:02:58 --> 00:03:00 >> if you if you're sitting here on planet
00:03:00 --> 00:03:05 Earth um what sort of you know in our
00:03:05 --> 00:03:11 locality uh in the um western spiral arm
00:03:11 --> 00:03:13 the galaxy it's the Orion spur where we
00:03:13 --> 00:03:17 are uh that spiral arm that we sit in um
00:03:17 --> 00:03:19 what's the it's so it's really a
00:03:19 --> 00:03:21 question about the density of stars in
00:03:21 --> 00:03:24 our region uh and that's something very
00:03:24 --> 00:03:25 well established because we know the
00:03:25 --> 00:03:29 distances of lots of stars. Uh so I'm
00:03:29 --> 00:03:32 I'm going to put it in much rounder
00:03:32 --> 00:03:39 figures. Uh but um if you look at uh out
00:03:39 --> 00:03:42 to a thousand light years, okay, so you
00:03:42 --> 00:03:44 got a a sphere of radius a thousand
00:03:44 --> 00:03:47 light years, then that's going to have
00:03:47 --> 00:03:50 something like 10 million stars in it.
00:03:50 --> 00:03:54 >> Wow. So that's more than what uh what um
00:03:54 --> 00:03:57 Justin's talking about. Uh but the way
00:03:57 --> 00:04:00 this changes uh it changes nonlinearly.
00:04:00 --> 00:04:03 Uh so I'm guessing so I'm going to take
00:04:03 --> 00:04:06 a guess that you know around 9 900 light
00:04:06 --> 00:04:10 years or thereabouts you would probably
00:04:10 --> 00:04:12 have something like 4 million stars
00:04:12 --> 00:04:15 which is the same
00:04:15 --> 00:04:18 mass as the mass of the uh super massive
00:04:18 --> 00:04:20 black hole at the center of the galaxy.
00:04:20 --> 00:04:21 So, it's actually quite a long way. You
00:04:22 --> 00:04:24 know, you're looking at um yeah, several
00:04:24 --> 00:04:27 hundred light years uh uh in in terms of
00:04:27 --> 00:04:29 radius.
00:04:29 --> 00:04:32 Uh and um it's actually I think you
00:04:32 --> 00:04:34 would probably be able to find a tool
00:04:34 --> 00:04:36 online. I haven't found it myself
00:04:36 --> 00:04:37 because I haven't really looked for it,
00:04:37 --> 00:04:39 but I bet you can find a tool that gives
00:04:39 --> 00:04:42 you the exact answer to that. Uh how
00:04:42 --> 00:04:44 many stars are within a radius of x
00:04:44 --> 00:04:47 number of light years? And if you put in
00:04:47 --> 00:04:49 a good guess of light years, you'll
00:04:49 --> 00:04:51 probably get the right number of of
00:04:51 --> 00:04:51 stars.
00:04:51 --> 00:04:53 >> Do you want me to test it?
00:04:53 --> 00:04:54 >> Yeah, if you can find one.
00:04:54 --> 00:04:56 >> Yeah, I've got an idea. So, what's the
00:04:56 --> 00:05:02 question? How many stars in uh say
00:05:02 --> 00:05:04 within 900 light years?
00:05:04 --> 00:05:07 >> Okay. See what it is. This is a life
00:05:08 --> 00:05:09 >> uh radius
00:05:09 --> 00:05:13 of 900 light years.
00:05:13 --> 00:05:15 Okay.
00:05:15 --> 00:05:18 Let's see what happens here. Um, I'll
00:05:18 --> 00:05:19 just make sure I ask the question
00:05:19 --> 00:05:22 correctly.
00:05:22 --> 00:05:26 And nothing. Oh, here we go. Uh,
00:05:26 --> 00:05:28 uh, it's saying
00:05:28 --> 00:05:31 10 to 15 million.
00:05:31 --> 00:05:33 >> Yeah. Um, which is different from the
00:05:33 --> 00:05:36 calculation I saw, which is 10 million
00:05:36 --> 00:05:38 in a thousand. So, drop it down a bit.
00:05:38 --> 00:05:40 Can you put it down to 500 light years?
00:05:40 --> 00:05:41 See what it says for that.
00:05:41 --> 00:05:44 >> Okay. This is AI I assume that
00:05:44 --> 00:05:46 >> is doing all this for you on
00:05:46 --> 00:05:49 >> Mr. I absolutely love it.
00:05:49 --> 00:05:53 >> Um two to two and a half million stars.
00:05:53 --> 00:05:55 >> Yeah. So it's it's somewhere between 500
00:05:56 --> 00:05:57 and a thousand light years.
00:05:57 --> 00:05:57 >> There you go.
00:05:57 --> 00:05:59 >> So you put in whatever number you like
00:05:59 --> 00:06:01 and it'll give you the right answer. And
00:06:01 --> 00:06:03 Justin can have a lot of fun doing that.
00:06:03 --> 00:06:04 It's a great question actually.
00:06:04 --> 00:06:07 >> It's working out the averages. So
00:06:07 --> 00:06:11 750 light years transposes to 7 to 8
00:06:11 --> 00:06:12 million stars. So
00:06:12 --> 00:06:13 >> yeah.
00:06:13 --> 00:06:15 >> Yeah.
00:06:15 --> 00:06:17 >> There you go. You could do this all day
00:06:17 --> 00:06:20 really.
00:06:20 --> 00:06:21 >> Um I don't think we've ever been asked
00:06:21 --> 00:06:22 that before.
00:06:22 --> 00:06:23 >> No, I don't think so either.
00:06:23 --> 00:06:26 >> Not in that that way. Um
00:06:26 --> 00:06:27 >> we have had questions about you know the
00:06:27 --> 00:06:29 density the average density of stars in
00:06:29 --> 00:06:31 the solar neighborhood and that's really
00:06:31 --> 00:06:32 what this is all about.
00:06:32 --> 00:06:32 >> Yeah.
00:06:32 --> 00:06:35 >> Uh but uh yeah good stuff Justin. Thank
00:06:35 --> 00:06:37 you for your question and greetings to
00:06:37 --> 00:06:38 me Melbourne. It's 42 in Melbourne
00:06:38 --> 00:06:39 today, I think.
00:06:39 --> 00:06:42 >> Yes. Um we've we've got 38 here today. I
00:06:42 --> 00:06:43 went and played golf in that this
00:06:44 --> 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 jigged by the
00:06:51 --> 00:06:52 end of it.
00:06:52 --> 00:06:52 >> Jiggered. That's
00:06:52 --> 00:06:53 >> jigged. I don't know where it comes
00:06:53 --> 00:06:53 from.
00:06:53 --> 00:06:55 >> Granddad used to use that.
00:06:55 --> 00:06:55 >> Yeah.
00:06:56 --> 00:06:59 >> Yeah. Ah, wheel it in. It's jigged.
00:06:59 --> 00:07:01 >> Yeah. It was uh it was a tough day out,
00:07:01 --> 00:07:03 I must say. Uh thanks, Justin. Our next
00:07:03 --> 00:07:06 question comes from Charles. Uh, but
00:07:06 --> 00:07:09 because I've been using chat GPT to
00:07:09 --> 00:07:10 solve all the pro riddles of the
00:07:10 --> 00:07:12 universe, I've lost the question. All
00:07:12 --> 00:07:13 right. If
00:07:13 --> 00:07:17 >> if the universe does cease expanding and
00:07:17 --> 00:07:19 retracts, does that mean the lifetime of
00:07:20 --> 00:07:24 the universe goes from untold trillion
00:07:24 --> 00:07:26 beyond trillions of years or just a
00:07:26 --> 00:07:29 measly few billion? This one comes from
00:07:29 --> 00:07:31 Charles in Brooklyn and New York. I was
00:07:31 --> 00:07:34 in Brooklyn. Not so long ago. Walked
00:07:34 --> 00:07:36 across the Brooklyn Bridge.
00:07:36 --> 00:07:36 >> Yeah.
00:07:36 --> 00:07:38 >> In about August. It was.
00:07:38 --> 00:07:40 >> Were you jigggered when you got to the
00:07:40 --> 00:07:40 end?
00:07:40 --> 00:07:42 >> I was jigged before I started cuz we've
00:07:42 --> 00:07:46 been walking all day.
00:07:46 --> 00:07:49 >> Yeah, I can imagine. Um I think Charles
00:07:49 --> 00:07:51 is right actually.
00:07:51 --> 00:07:56 Uh look, it it may still
00:07:56 --> 00:07:59 I mean the the difference is really that
00:07:59 --> 00:08:02 if if we have a universe which is
00:08:02 --> 00:08:05 dominated by a constant
00:08:05 --> 00:08:08 uh 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
00:08:16 --> 00:08:18 go on expanding forever. M
00:08:18 --> 00:08:21 >> um so and and Charles summarizes that by
00:08:21 --> 00:08:23 untold untold trillions beyond trillions
00:08:23 --> 00:08:27 which I guess is forever. Uh but if the
00:08:27 --> 00:08:30 dark energy is reducing and that's
00:08:30 --> 00:08:32 certainly being hinted at by the latest
00:08:32 --> 00:08:33 observations
00:08:33 --> 00:08:37 then um we don't know what what's going
00:08:38 --> 00:08:39 to happen because we don't know how
00:08:39 --> 00:08:42 quickly it's reducing and whether it may
00:08:42 --> 00:08:44 even go negative so that suddenly
00:08:44 --> 00:08:46 there's a positive attraction of stuff.
00:08:46 --> 00:08:49 it's not being repelled like it is now,
00:08:49 --> 00:08:50 that could bring it down to a few
00:08:50 --> 00:08:53 billion years. Uh but if it just goes
00:08:53 --> 00:08:56 settles back to something where it's the
00:08:56 --> 00:08:58 normal gravitational content of the
00:08:58 --> 00:09:01 universe that dominates everything, uh
00:09:01 --> 00:09:02 and so in other words, all the galaxies
00:09:02 --> 00:09:05 are pulling each other together. Uh then
00:09:05 --> 00:09:07 you you might be talking about a bit
00:09:07 --> 00:09:09 longer. It might still be a few trillion
00:09:09 --> 00:09:11 years rather than a few measly billions.
00:09:12 --> 00:09:14 Uh but uh interesting question, a nice
00:09:14 --> 00:09:16 thought experiment there from Charles in
00:09:16 --> 00:09:16 Brooklyn.
00:09:16 --> 00:09:19 >> Yes, indeed. And
00:09:19 --> 00:09:22 as you said, the the theory about when
00:09:22 --> 00:09:24 like I think I've said it before, when I
00:09:24 --> 00:09:26 was growing up, it was always assumed
00:09:26 --> 00:09:28 that the universe would stop expanding
00:09:28 --> 00:09:30 and then start sort of folding back in
00:09:30 --> 00:09:31 on itself.
00:09:31 --> 00:09:34 >> Uh the big crunch or the gab gibb,
00:09:34 --> 00:09:36 >> whatever you want to call it. But um
00:09:36 --> 00:09:39 then then it was decided that uh it was
00:09:39 --> 00:09:40 going to continue expanding at an
00:09:40 --> 00:09:43 accelerating rate. Now they've decided
00:09:43 --> 00:09:45 and and that could lead to a big rip.
00:09:45 --> 00:09:47 But now it's looking more like the
00:09:47 --> 00:09:50 acceleration is slowing
00:09:50 --> 00:09:52 and now all the bets are off and we're
00:09:52 --> 00:09:55 back to back to square one or something.
00:09:55 --> 00:09:57 I'm not sure. It's it's
00:09:57 --> 00:09:59 >> Yeah. How do you prove it?
00:09:59 --> 00:09:59 >> Well,
00:09:59 --> 00:10:02 >> I mean you you can you can Yeah. You you
00:10:02 --> 00:10:05 can measure that what's going on.
00:10:05 --> 00:10:06 get. Yeah.
00:10:06 --> 00:10:08 >> And and that's that's the trick. I mean,
00:10:08 --> 00:10:09 you know, if we'd been having this
00:10:09 --> 00:10:12 conversation a year ago, we'd have been
00:10:12 --> 00:10:14 >> completely sold on the the big rip
00:10:14 --> 00:10:16 because there was nothing to suggest
00:10:16 --> 00:10:17 that the expansion
00:10:17 --> 00:10:19 >> was going to slow down. The expansion
00:10:19 --> 00:10:21 was known to be accelerating. That was
00:10:21 --> 00:10:23 discovered in 1998.
00:10:23 --> 00:10:25 >> Um but it's only within the last year
00:10:25 --> 00:10:27 with um results from project called
00:10:27 --> 00:10:31 DESI. uh the dark energy survey
00:10:31 --> 00:10:34 instrument I think is the right thing.
00:10:34 --> 00:10:39 Uh but that's basically established that
00:10:39 --> 00:10:40 established is the wrong word. It has
00:10:40 --> 00:10:43 suggested that the acceleration is
00:10:44 --> 00:10:46 slower now than it was a couple of
00:10:46 --> 00:10:48 billion years ago.
00:10:48 --> 00:10:51 >> Yeah. uh and that uh is leading people
00:10:52 --> 00:10:54 to the hint that maybe the acceleration
00:10:54 --> 00:10:56 will eventually not be there and that's
00:10:56 --> 00:10:58 why we might get the gab gibb. But I
00:10:58 --> 00:11:00 think we are we're still talking about I
00:11:00 --> 00:11:02 think really think it's trillions of
00:11:02 --> 00:11:03 years into the future.
00:11:03 --> 00:11:05 >> It's like blowing up a balloon though
00:11:05 --> 00:11:07 when you start it goes out fast but as
00:11:07 --> 00:11:10 it gets bigger the expansion continues
00:11:10 --> 00:11:13 but it just it slows down. It's the same
00:11:13 --> 00:11:15 thing.
00:11:16 --> 00:11:19 >> Okay.
00:11:19 --> 00:11:22 Maybe not. It does remind me um we we
00:11:22 --> 00:11:25 got a question in German the other day
00:11:25 --> 00:11:27 because apparently now what they're
00:11:27 --> 00:11:28 doing on YouTube, the people who listen
00:11:28 --> 00:11:32 to us on YouTube is uh it's now
00:11:32 --> 00:11:34 English-speaking
00:11:34 --> 00:11:37 YouTube podcasts are being translated
00:11:37 --> 00:11:41 into other languages. So apparently we
00:11:41 --> 00:11:43 were being heard in German and a German
00:11:43 --> 00:11:46 listener on YouTube sent us a question
00:11:46 --> 00:11:50 in German and we had to translate it
00:11:50 --> 00:11:52 into English so that we knew what he was
00:11:52 --> 00:11:53 asking. But I don't think it translated
00:11:53 --> 00:11:56 very well. But it was something about
00:11:56 --> 00:11:58 how do you prove the expansion of the
00:11:58 --> 00:12:01 universe if you haven't found a
00:12:01 --> 00:12:02 particle?
00:12:02 --> 00:12:05 >> Well, I I wasn't sure whether I I I did
00:12:05 --> 00:12:06 look at that question. And in fact, I
00:12:06 --> 00:12:08 did send an answer which I think um you
00:12:08 --> 00:12:10 might have put through some language
00:12:10 --> 00:12:14 mangling s um system to give a the
00:12:14 --> 00:12:18 answer in German. Uh mut's
00:12:18 --> 00:12:24 crap. Uh so um so that's K K R Ap. It's
00:12:24 --> 00:12:27 not
00:12:27 --> 00:12:30 >> uh um so um I think I wasn't sure
00:12:30 --> 00:12:33 whether it was somebody talking about
00:12:33 --> 00:12:35 dark energy or dark matter. Yeah, I
00:12:35 --> 00:12:36 wasn't sure either.
00:12:36 --> 00:12:38 >> But dark matter, yes, we do need to know
00:12:38 --> 00:12:41 what the particles are. And um I hope
00:12:41 --> 00:12:42 we'll discover them. I I'm not
00:12:42 --> 00:12:44 optimistic. We're going to find that out
00:12:44 --> 00:12:47 during 2026, but you never know.
00:12:47 --> 00:12:48 Anything's possible.
00:12:48 --> 00:12:50 >> Thanks for your question, Charles. This
00:12:50 --> 00:12:53 is Space Nuts uh Q&A edition with Andrew
00:12:53 --> 00:12:56 Dunley and Fred Watson.
00:12:56 --> 00:12:57 >> Now, let's take a break from the show to
00:12:57 --> 00:13:00 tell you about our sponsor, NordVPN.
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00:14:21 --> 00:14:24 >> Three, two, one.
00:14:24 --> 00:14:27 >> Spacenuts. Uh, next up we've got Dean
00:14:27 --> 00:14:30 who's got a kind of a what if question
00:14:30 --> 00:14:32 for I love these Fred. These are my
00:14:32 --> 00:14:34 favorite questions. What if this
00:14:34 --> 00:14:35 happens?
00:14:35 --> 00:14:36 >> Hi Fred and Andrew. This is Dean in
00:14:36 --> 00:14:38 Redcliffe in Queensland. Thanks for
00:14:38 --> 00:14:41 answering my previous questions. Today
00:14:41 --> 00:14:43 I'm asking about a thought experiment
00:14:43 --> 00:14:45 that was once used to consider issues
00:14:45 --> 00:14:47 around the speed of light. I think it
00:14:47 --> 00:14:49 may have been Einstein. The scenario
00:14:49 --> 00:14:51 asks, "What happens if our 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
00:14:56 --> 00:14:58 would there be a delay if the gravity
00:14:58 --> 00:15:01 effect travels at a particular speed?"
00:15:01 --> 00:15:03 Before I get to my actual question, I
00:15:03 --> 00:15:05 want to ask about thought experiments.
00:15:05 --> 00:15:07 They seem like a useful tool to get
00:15:07 --> 00:15:09 started on a problem, but I question the
00:15:09 --> 00:15:12 value of an experiment where the initial
00:15:12 --> 00:15:14 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
00:15:24 --> 00:15:26 the idea of the sun disappearing, I'd
00:15:26 --> 00:15:28 say that gravity is not a force
00:15:28 --> 00:15:30 generated by the sun, but is a
00:15:30 --> 00:15:32 compression of the spaceime around it.
00:15:32 --> 00:15:35 If the sun disappeared instantly, then
00:15:35 --> 00:15:38 spacetime would decompress back to a
00:15:38 --> 00:15:40 smooth state except for the planets and
00:15:40 --> 00:15:43 moons still in the vicinity. There would
00:15:43 --> 00:15:44 also have to be an unwinding of the
00:15:44 --> 00:15:47 frame dragging around where the sun was.
00:15:47 --> 00:15:49 Let me know if I'm wrong, but it seems
00:15:49 --> 00:15:52 to me that a sudden decompression and
00:15:52 --> 00:15:54 unwinding of some local spacetime would
00:15:54 --> 00:15:57 be violent, but would not be instant.
00:15:57 --> 00:16:00 Imagine the 2D model of this using a
00:16:00 --> 00:16:02 large rubber sheet with a heavy ball in
00:16:02 --> 00:16:04 the center representing the sun. If you
00:16:04 --> 00:16:07 suddenly removed the ball, then the
00:16:07 --> 00:16:09 warped sheet would snap back into a flat
00:16:09 --> 00:16:13 plane quickly, 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 --> 00:16:25 transition to the complete lack of sun's
00:16:25 --> 00:16:26 gravity while the local spaceime is
00:16:26 --> 00:16:29 settling into a decompressed state. I
00:16:29 --> 00:16:31 also expect there would be a compression
00:16:31 --> 00:16:34 wave i.e. a gravity wave generated from
00:16:34 --> 00:16:39 an event like this. What do you think?
00:16:39 --> 00:16:41 There's a lot packaged into that. Uh
00:16:41 --> 00:16:44 thank you Dean. Uh so there's a question
00:16:44 --> 00:16:46 or two questions effectively uh that
00:16:46 --> 00:16:49 he's asking about. Um what's the worth
00:16:49 --> 00:16:54 of thought experiments? Uh now
00:16:54 --> 00:16:56 yeah
00:16:56 --> 00:16:58 I I just did a little bit of research
00:16:58 --> 00:17:00 while I was listening to him and that to
00:17:00 --> 00:17:02 give you an idea of thought experiments
00:17:02 --> 00:17:04 u there have been many famous ones over
00:17:04 --> 00:17:07 the years. Schroinger's cat. Uh,
00:17:07 --> 00:17:10 Galileo's falling bodies.
00:17:10 --> 00:17:12 Um, there's one called the trolley
00:17:12 --> 00:17:14 problem. I have to look into that. Don't
00:17:14 --> 00:17:16 know what that one is. But, um, yeah,
00:17:16 --> 00:17:18 they have been very helpful over the
00:17:18 --> 00:17:21 years. I I do think there is worth in
00:17:21 --> 00:17:23 thought experiments. It's a way of
00:17:23 --> 00:17:25 exploring something that we can't solve
00:17:25 --> 00:17:26 yet because we haven't got the
00:17:26 --> 00:17:30 technology to solve it. uh it gives you
00:17:30 --> 00:17:32 something to work with and it tosses
00:17:32 --> 00:17:35 around ideas that may provide solutions.
00:17:35 --> 00:17:39 It's um I think I yeah I I love I love
00:17:39 --> 00:17:41 the concept. I think it's very valuable.
00:17:41 --> 00:17:44 If it's how we start making inquiries
00:17:44 --> 00:17:45 with thought experiments, you know, if
00:17:46 --> 00:17:48 we if we didn't use our imaginations,
00:17:48 --> 00:17:49 then we probably wouldn't solve
00:17:49 --> 00:17:51 anything.
00:17:51 --> 00:17:54 >> Exactly. Um a great answer actually,
00:17:54 --> 00:17:56 Andrew. Thank you. I um I I'll I'll just
00:17:56 --> 00:17:59 go home and talk about
00:17:59 --> 00:18:01 No, I I entirely agree. Um the one that
00:18:01 --> 00:18:03 came to my mind was a thought experiment
00:18:03 --> 00:18:06 that had it had the real experiment been
00:18:06 --> 00:18:08 carried out, uh physics would have grown
00:18:08 --> 00:18:11 to a halt very quickly. And that's uh uh
00:18:11 --> 00:18:15 Einstein's musing in 197
00:18:15 --> 00:18:17 about what would happen if he jumped off
00:18:17 --> 00:18:20 the top of the patent building in Burn,
00:18:20 --> 00:18:21 which is where he was working at the
00:18:21 --> 00:18:24 time. He was a patent administrator.
00:18:24 --> 00:18:26 Uh and so he imagined himself jumping
00:18:26 --> 00:18:28 off the top of the building. Uh so if he
00:18:28 --> 00:18:30 carried that out as a real experiment,
00:18:30 --> 00:18:31 that could have been the end of a lot of
00:18:31 --> 00:18:32 really good stuff.
00:18:32 --> 00:18:33 >> Yeah.
00:18:33 --> 00:18:36 >> Uh so uh but what it gave him was the
00:18:36 --> 00:18:37 inspiration
00:18:37 --> 00:18:40 uh to um define what we now call the
00:18:40 --> 00:18:43 principle of equivalence. The fact that
00:18:43 --> 00:18:46 acceleration and gravity are to all
00:18:46 --> 00:18:50 intents and purposes the same. Um so and
00:18:50 --> 00:18:51 the fact that you're accelerating
00:18:51 --> 00:18:54 towards the earth uh cancels out the
00:18:54 --> 00:18:55 earth's gravity because the two are
00:18:56 --> 00:18:58 exactly equal. And that's why as you as
00:18:58 --> 00:18:59 you you know as you jump off the
00:19:00 --> 00:19:02 building uh your pipe floats out of your
00:19:02 --> 00:19:04 mouth if you've got money in your hands
00:19:04 --> 00:19:05 or something like that it just floats
00:19:05 --> 00:19:07 away. You can actually demonstrate it
00:19:07 --> 00:19:08 very easily on a trampoline.
00:19:08 --> 00:19:09 >> Yes.
00:19:09 --> 00:19:11 >> Uh without jumping off buildings. But it
00:19:11 --> 00:19:12 was that thought experiment that led to
00:19:12 --> 00:19:15 the principle of equivalence which told
00:19:15 --> 00:19:17 Einstein that gravity is actually a
00:19:17 --> 00:19:20 geometrical problem rather than you know
00:19:20 --> 00:19:23 something entwined in physics. We know
00:19:23 --> 00:19:25 it is we still don't really understand
00:19:25 --> 00:19:27 the physics of gravity but the geometry
00:19:27 --> 00:19:31 works so well uh in the general theory
00:19:31 --> 00:19:34 of relativity that um the principle of
00:19:34 --> 00:19:36 equivalence has been demonstrated to be
00:19:36 --> 00:19:38 accurate to within one part in 10 to the
00:19:38 --> 00:19:40 18 or something. I can't remember what
00:19:40 --> 00:19:42 the latest the latest thing is uh that
00:19:42 --> 00:19:45 it does work very very well indeed. Uh
00:19:45 --> 00:19:47 so yes, thought experiments are great.
00:19:47 --> 00:19:49 Um now the thought experiment regarding
00:19:49 --> 00:19:51 taking the sun out the solar system is
00:19:51 --> 00:19:53 very well established as to what
00:19:53 --> 00:19:56 happens. Uh the the earth feels nothing
00:19:56 --> 00:19:59 for the first eight minutes. Uh because
00:19:59 --> 00:20:01 gravitational energy travels at the same
00:20:01 --> 00:20:05 speed as light. uh and once uh the the
00:20:05 --> 00:20:07 message that there is no gravitating
00:20:07 --> 00:20:09 gravitating body in the center of the
00:20:09 --> 00:20:12 solar system reaches the earth 8 minutes
00:20:12 --> 00:20:14 after the sun has gone um the earth just
00:20:14 --> 00:20:17 carries on in a straight line.
00:20:17 --> 00:20:20 >> Uh uh so that's uh that's well
00:20:20 --> 00:20:25 understood. So I think um I think uh um
00:20:25 --> 00:20:29 Dean's um uh thinking about the you know
00:20:29 --> 00:20:31 the the two-dimensional idea of the
00:20:31 --> 00:20:33 gravity well which is a great way of
00:20:33 --> 00:20:36 thinking of the way uh mass distorts
00:20:36 --> 00:20:39 time. Uh we're we're used to thinking
00:20:39 --> 00:20:41 okay you've got a a rock in the middle
00:20:41 --> 00:20:43 of a trampoline it's pulling it down.
00:20:43 --> 00:20:44 You take the rock away the trampoline
00:20:44 --> 00:20:47 just springs back. Uh but actually uh it
00:20:47 --> 00:20:50 wouldn't the spacetime would take uh
00:20:50 --> 00:20:53 time uh the the basically the message
00:20:53 --> 00:20:55 that it had sprung back would take would
00:20:55 --> 00:20:57 travel outwards at the speed of light.
00:20:57 --> 00:20:59 Uh and so it's the same you know the
00:21:00 --> 00:21:01 same thing looking at it either as a
00:21:01 --> 00:21:05 gravity well or as gravitational energy
00:21:05 --> 00:21:07 or radiation. One day we'll have a
00:21:07 --> 00:21:08 quantum theory of gravity and we'll be
00:21:08 --> 00:21:10 able to talk about gravitons uh which
00:21:10 --> 00:21:12 are the hypothetical particles that
00:21:12 --> 00:21:14 carry gravity and they move at the speed
00:21:14 --> 00:21:16 of light. Of course, you we we should
00:21:16 --> 00:21:18 mention the catastrophe that would then
00:21:18 --> 00:21:20 follow eight minutes after the the sun
00:21:20 --> 00:21:22 suddenly disappeared. For example,
00:21:22 --> 00:21:25 Pavlov's dog and Schroing Schroinger's
00:21:25 --> 00:21:26 cat would live together.
00:21:26 --> 00:21:28 >> Yes.
00:21:28 --> 00:21:32 >> So, they would Yeah. Oh, dear me. That's
00:21:32 --> 00:21:33 Yes. That
00:21:33 --> 00:21:35 >> would be would be a mess.
00:21:35 --> 00:21:36 >> Things are good.
00:21:36 --> 00:21:38 >> Well, how long would the Earth last
00:21:38 --> 00:21:39 after that effect?
00:21:39 --> 00:21:41 >> Uh, it would be fine. It would just keep
00:21:41 --> 00:21:43 on going. um you know assuming there
00:21:43 --> 00:21:46 wasn't some sort of um uh catastrophic
00:21:46 --> 00:21:48 event that caused the sun to disappear.
00:21:48 --> 00:21:50 If you just remove the sun without
00:21:50 --> 00:21:52 anything explosive or and anything which
00:21:52 --> 00:21:55 you could do in a thought experiment um
00:21:55 --> 00:21:57 the earth just keeps keeps on going. It
00:21:57 --> 00:21:58 would be like Voyager one and Voyager 2.
00:21:58 --> 00:22:01 It will get very very cold. Uh we as a
00:22:01 --> 00:22:02 species would almost certainly not
00:22:02 --> 00:22:03 survive. No.
00:22:03 --> 00:22:05 >> Uh because the temperatures would
00:22:05 --> 00:22:08 plummet to very low levels indeed. Um,
00:22:08 --> 00:22:11 so yes, an interesting scenario.
00:22:12 --> 00:22:13 >> Doesn't sound like much fun.
00:22:13 --> 00:22:14 >> It's not fun. No.
00:22:14 --> 00:22:15 >> No. Anyway,
00:22:15 --> 00:22:16 >> think about it, though.
00:22:16 --> 00:22:19 >> We're we're stuck with um with the sun
00:22:19 --> 00:22:22 for several more billion years.
00:22:22 --> 00:22:24 >> Yes, indeed we are.
00:22:24 --> 00:22:27 >> Yeah. But, uh, great questions, Dean. I
00:22:27 --> 00:22:29 really enjoy those kinds of questions.
00:22:29 --> 00:22:33 So, uh, yeah, thanks for sending it in.
00:22:33 --> 00:22:34 >> Let's take a break from the show to tell
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00:24:00 --> 00:24:03 3 2 1
00:24:03 --> 00:24:07 >> Space nuts. Our final question today
00:24:07 --> 00:24:09 comes from Patrick. He's a conspiracy
00:24:09 --> 00:24:11 theorist. Well, he's probably not, but I
00:24:11 --> 00:24:13 I do like this question because I I
00:24:13 --> 00:24:16 didn't know this. Uh the Voyager
00:24:16 --> 00:24:18 spacecraft have plaques on them. I did
00:24:18 --> 00:24:21 know that. And as far as I can find out,
00:24:21 --> 00:24:23 both show them leaving the solar system
00:24:23 --> 00:24:27 ecliptic uh between Jupiter and Saturn.
00:24:27 --> 00:24:30 That didn't happen. And from what I've
00:24:30 --> 00:24:32 read, Voyager 1 left after a visit to
00:24:32 --> 00:24:36 Titan while Voyager 2 carried on. Uh
00:24:36 --> 00:24:39 Voyager 1 has a chance to visit uh had a
00:24:39 --> 00:24:41 chance to visit Pluto. So here's the
00:24:41 --> 00:24:43 questions. Why does the plaque show an
00:24:43 --> 00:24:46 early departure of Voyager 1 and why
00:24:46 --> 00:24:49 does Voyager 2's path show the same? Um
00:24:49 --> 00:24:52 hope you both had a wonderful Christmas
00:24:52 --> 00:24:56 and um hello from a wet northern island,
00:24:56 --> 00:24:59 Patrick. wet Northern Ireland. It's
00:24:59 --> 00:25:01 probably still wet just like we're still
00:25:01 --> 00:25:03 dry. This we've hit the hottest driest
00:25:03 --> 00:25:05 part of the year in Australia and um it
00:25:06 --> 00:25:09 is it is dry as a chip as we say in this
00:25:09 --> 00:25:13 country at the moment. Um yeah. Okay. I
00:25:13 --> 00:25:15 I didn't realize that the plaques had
00:25:15 --> 00:25:18 the supposed path of both spacecraft,
00:25:18 --> 00:25:20 but they didn't go that way. Um did they
00:25:20 --> 00:25:24 get pulled over by an RBT perhaps?
00:25:24 --> 00:25:27 Um, I thought you'd have spotted this
00:25:27 --> 00:25:29 one right at the start, Andrew.
00:25:29 --> 00:25:32 >> Really?
00:25:32 --> 00:25:33 >> Is he playing us?
00:25:33 --> 00:25:36 >> No. Uh, no. He's He's got his spacecraft
00:25:36 --> 00:25:38 mixed up because it's the two the two
00:25:38 --> 00:25:41 pioneers that show the spacecraft
00:25:41 --> 00:25:43 leaving the solar system between the
00:25:43 --> 00:25:45 orbits of Jupiter.
00:25:45 --> 00:25:48 >> I never even thought of that.
00:25:48 --> 00:25:49 >> Voyager doesn't actually have a diagram
00:25:49 --> 00:25:51 like that on it. He's got mostly
00:25:51 --> 00:25:53 diagrams how to play the golden record.
00:25:53 --> 00:25:54 >> That's right.
00:25:54 --> 00:25:57 >> 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 wrong.
00:26:03 --> 00:26:04 It's it's not the Voyager spacecraft
00:26:04 --> 00:26:06 that had the diagram. It's the Pioneers.
00:26:06 --> 00:26:09 >> Well, how about that?
00:26:09 --> 00:26:11 >> Yeah, I'm just looking at them now.
00:26:11 --> 00:26:13 Okay,
00:26:13 --> 00:26:15 that's really And it's got the the human
00:26:16 --> 00:26:17 being on it and all that.
00:26:17 --> 00:26:19 >> I actually really like the Pioneer uh
00:26:19 --> 00:26:20 plugs. I think they're
00:26:20 --> 00:26:23 >> elegant and decorative and
00:26:23 --> 00:26:25 >> uh tell the story just show aliens just
00:26:26 --> 00:26:27 how
00:26:27 --> 00:26:29 >> chewy we are and you know
00:26:29 --> 00:26:31 >> how tasty we might be
00:26:31 --> 00:26:33 >> and how um unfortunate that male
00:26:33 --> 00:26:36 appendages. It's um it's well below par.
00:26:36 --> 00:26:38 But um
00:26:38 --> 00:26:41 and the other the other factor is that
00:26:41 --> 00:26:41 um
00:26:41 --> 00:26:42 >> thanks Andrew.
00:26:42 --> 00:26:44 >> Aliens will look at these two human
00:26:44 --> 00:26:48 figures and they'll go she does not like
00:26:48 --> 00:26:49 him. that.
00:26:49 --> 00:26:51 >> Yeah, that's right.
00:26:51 --> 00:26:53 >> The body language is not positive.
00:26:54 --> 00:26:55 >> That's true. There is body language on
00:26:55 --> 00:26:58 there that really Yeah, I I'm with you
00:26:58 --> 00:27:01 on that actually.
00:27:01 --> 00:27:03 >> It's all about body language. Yeah.
00:27:03 --> 00:27:04 >> So, now I'm going to have to look up
00:27:04 --> 00:27:07 what the Voyager plaques look like.
00:27:07 --> 00:27:08 >> Yeah.
00:27:08 --> 00:27:10 >> Ah, see it's Yes. It's the golden record
00:27:10 --> 00:27:13 with the um um bits and bobs on them
00:27:13 --> 00:27:15 >> stuff on it. Yeah. Yeah.
00:27:15 --> 00:27:17 >> Okay.
00:27:17 --> 00:27:20 So, um, right idea, wrong wrong
00:27:20 --> 00:27:22 spacecraft is basically the answer to
00:27:22 --> 00:27:24 the question.
00:27:24 --> 00:27:26 >> Uh, I think that's correct. So,
00:27:26 --> 00:27:27 >> yeah. So,
00:27:27 --> 00:27:28 >> and, um, look,
00:27:28 --> 00:27:30 >> I think we can safely say that Voyager 1
00:27:30 --> 00:27:32 and Voyager 2 did go where we intended
00:27:32 --> 00:27:32 them to.
00:27:32 --> 00:27:33 >> Yes, they did.
00:27:33 --> 00:27:34 >> Go.
00:27:34 --> 00:27:35 >> And they're still going.
00:27:35 --> 00:27:37 >> Yeah, indeed they are. Voyager 2, well,
00:27:37 --> 00:27:39 Pioneer 10 and 11 are as well. Uh,
00:27:39 --> 00:27:41 Voyager 2 was the one that flew by
00:27:41 --> 00:27:44 Uranus and Neptune as well as Jupiter
00:27:44 --> 00:27:46 and Saturn. fantastic details that came
00:27:46 --> 00:27:49 from those two spacecraft. As Voyager
00:27:49 --> 00:27:51 One, as we've said many times before, is
00:27:51 --> 00:27:55 the most distant human-made object and
00:27:55 --> 00:27:58 is still on its way. It's almost a light
00:27:58 --> 00:27:59 day away. We should have a little party
00:27:59 --> 00:28:01 at Space Nots when it crosses a light
00:28:01 --> 00:28:04 day uh the light day boundary.
00:28:04 --> 00:28:07 >> Yeah. Which is happening in about 500
00:28:07 --> 00:28:08 years from now. No, I'm not sure.
00:28:08 --> 00:28:10 >> It's uh can't be that far away.
00:28:10 --> 00:28:12 >> Yeah, it's a few years. Yeah, a couple
00:28:12 --> 00:28:12 of years. I think
00:28:12 --> 00:28:15 >> it's about 23 light hours at the moment.
00:28:15 --> 00:28:17 Uh so it'll be Yeah. four or five years
00:28:18 --> 00:28:18 and
00:28:18 --> 00:28:20 >> Yeah. Wow. Yeah. But we should do
00:28:20 --> 00:28:21 something special about that.
00:28:21 --> 00:28:22 >> We should do that.
00:28:22 --> 00:28:23 >> Yes.
00:28:23 --> 00:28:25 >> All right. Um well, that was easily
00:28:25 --> 00:28:26 solved. Thanks for the question, though,
00:28:26 --> 00:28:29 Patrick. It sort of Yeah, it reminds us
00:28:29 --> 00:28:31 that as time goes on, you can sort of
00:28:31 --> 00:28:34 mix two totally different things
00:28:34 --> 00:28:38 together and yeah, it throws throws your
00:28:38 --> 00:28:41 brain out. Um, it reminds me of a story
00:28:41 --> 00:28:45 once where um, oh gosh, a guy I worked
00:28:45 --> 00:28:49 with in radio did a special about um,
00:28:49 --> 00:28:51 uh, Dean Martin and Jerry Lewis getting
00:28:51 --> 00:28:53 back together. Remember them? Yeah.
00:28:53 --> 00:28:55 >> Yeah. But he thought it was Jerry Lee
00:28:55 --> 00:28:57 Lewis and
00:28:57 --> 00:28:59 >> so he did this whole special with Jerry
00:28:59 --> 00:29:01 Lee Lewis music and
00:29:01 --> 00:29:04 >> it completely wrong.
00:29:04 --> 00:29:04 >> Yes.
00:29:04 --> 00:29:06 >> But it can happen.
00:29:06 --> 00:29:10 >> It can happen. Yeah. I um Yes, I looked
00:29:10 --> 00:29:11 at some research recently where they'd
00:29:11 --> 00:29:14 got the wrong telescope. Uh
00:29:14 --> 00:29:16 >> yeah, it's like getting the color of the
00:29:16 --> 00:29:17 universe wrong when you make
00:29:17 --> 00:29:19 >> That's another one. That's correct. Yes.
00:29:19 --> 00:29:20 Yeah.
00:29:20 --> 00:29:22 >> Oh, there's a list of them. There's a
00:29:22 --> 00:29:24 list of them. So, don't feel bad,
00:29:24 --> 00:29:27 Patrick. It happens to the best of us.
00:29:27 --> 00:29:28 >> Uh but thanks for the question. Lovely
00:29:28 --> 00:29:29 to hear from you. If you've got
00:29:29 --> 00:29:31 questions for us, please send them in to
00:29:31 --> 00:29:33 us via our website. Just go to
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00:29:36 --> 00:29:38 or spacenuts.io
00:29:38 --> 00:29:41 if you're a lazy typist and click on the
00:29:41 --> 00:29:44 AMA button up the top and you can send
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00:29:49 --> 00:29:51 So if you're YouTube listener, please uh
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00:29:53 --> 00:29:56 you. Uh and uh don't forget reviews. We
00:29:56 --> 00:29:58 we really appreciate your reviews. The
00:29:58 --> 00:30:01 more reviews the better. Um, I mean it's
00:30:01 --> 00:30:04 an astronomy podcast, so you know, um,
00:30:04 --> 00:30:06 five stars would be the absolute
00:30:06 --> 00:30:09 minimum, I would expect. That's up to
00:30:09 --> 00:30:12 you. No influence here. No influence
00:30:12 --> 00:30:12 here.
00:30:12 --> 00:30:13 >> 4 million stars. That's
00:30:13 --> 00:30:16 >> 4 million stars. Yes. Deal.
00:30:16 --> 00:30:18 >> Uh, and um, yeah, if you'd like to do
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00:30:37 --> 00:30:39 Uh Fred, we are done. Thank you so much
00:30:39 --> 00:30:40 for answering those questions.
00:30:40 --> 00:30:42 >> Oh, it's a pleasure. It's um always good
00:30:42 --> 00:30:47 to interact with our four listeners.
00:30:47 --> 00:30:50 >> We've only got four at a time.
00:30:50 --> 00:30:52 >> Yeah. No, it's good. And thank you very
00:30:52 --> 00:30:55 much again as always, Andrew, for being
00:30:55 --> 00:30:56 the host of Space Notes.
00:30:56 --> 00:30:58 >> Oh, my great pleasure. It's good fun.
00:30:58 --> 00:31:00 Uh, Professor 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 Hugh in the studio,
00:31:04 --> 00:31:06 couldn't be with us today because he was
00:31:06 --> 00:31:09 doing a thought experiment.
00:31:09 --> 00:31:13 Uh, where he didn't exist.
00:31:13 --> 00:31:15 What more can I say? Uh, and from me,
00:31:15 --> 00:31:17 Andrew Dunley, thanks for your company.
00:31:17 --> 00:31:18 We'll catch you on the next episode of
00:31:18 --> 00:31:20 Space Nuts. Bye-bye.
00:31:20 --> 00:31:22 >> Space Nuts. You've been listening to the
00:31:22 --> 00:31:25 Space Nuts podcast
00:31:25 --> 00:31:28 >> available at Apple Podcasts, Spotify,
00:31:28 --> 00:31:31 iHeart Radio, or your favorite podcast
00:31:31 --> 00:31:33 player. You can also stream on demand at
00:31:33 --> 00:31:36 byes.com. This has been another quality
00:31:36 --> 00:31:41 podcast production from byes.com.