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In this thought-provoking Q&A episode of Space Nuts, host Andrew Dunkley and the ever-insightful Professor Fred Watson dive into a variety of compelling questions from listeners. They tackle the intriguing concept of the universe potentially being born inside a black hole, explore a new theory of gravity, and discuss the ongoing search for the elusive Planet Nine.
Episode Highlights:
- The Universe Inside a Black Hole: Listener Ash from Brisbane poses a fascinating question about the possibility of our universe being trapped inside a black hole and the implications of such a theory. Andrew and Fred Watson discuss the mechanics of black holes and what it would mean for our existence.
- A New Gravity Theory: Casey from Colorado asks about the latest advancements in gravity theories, prompting a discussion on the unification of quantum field theory and relativity, and the potential breakthroughs from Finnish researchers that could reshape our understanding of gravity.
- Understanding Hubble Tension: The duo explains the concept of Hubble tension, highlighting the discrepancies between two methods of measuring the universe's expansion rate and what this could mean for cosmology.
- The Quest for Planet Nine: Simon from New South Wales raises questions about the search for Planet Nine and the methods used to detect it, while Joe from Washington inquires about the limits of gravitational assists for interstellar travel, leading to a discussion on the practicality of such missions.
For more Space Nuts, including our continually updating newsfeed and to listen to all our episodes, visit our website. Follow us on social media at SpaceNutsPod on Facebook, X, YouTube Music, Tumblr, Instagram, and TikTok. We love engaging with our community, so be sure to drop us a message or comment on your favourite platform.
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Stay curious, keep looking up, and join us next time for more stellar insights and cosmic wonders. Until then, clear skies and happy stargazing.
(00:00) Welcome to Space Nuts with Andrew Dunkley and Fred Watson Watson
(01:20) Discussion on the universe inside a black hole
(15:00) New theory of gravity from Finnish researchers
(25:30) Explaining Hubble tension
(35:00) The search for Planet Nine and gravitational assists
For commercial-free versions of Space Nuts, join us on Patreon, Supercast, Apple Podcasts, or become a supporter here: https://www.spreaker.com/podcast/space-nuts-astronomy-insights-cosmic-discoveries--2631155/support.
00:00:00 --> 00:00:02 Andrew Dunkley: Hi there. Thanks for joining us. This is a Q
00:00:02 --> 00:00:04 and A edition of Space Nuts. My name is
00:00:04 --> 00:00:06 Andrew Dunkley. It's good to have your
00:00:06 --> 00:00:09 company. Uh, today, uh, we will be
00:00:09 --> 00:00:12 hearing questions about, uh, the
00:00:12 --> 00:00:14 universe being inside a black hole. In fact,
00:00:14 --> 00:00:16 I think they're suggesting it was born in a
00:00:16 --> 00:00:19 black hole and is stuck in there. And how do
00:00:19 --> 00:00:21 we get out? We'll also be looking at a new
00:00:21 --> 00:00:24 gravity theory. Uh, theory Hubble tension.
00:00:25 --> 00:00:28 Not surprisingly, questions about planet nine
00:00:28 --> 00:00:30 with the most recent announcement of
00:00:30 --> 00:00:31 something being out there that's not planet
00:00:32 --> 00:00:34 nine. And, um, getting
00:00:35 --> 00:00:38 gravity assistance to Max Delta V.
00:00:38 --> 00:00:40 Those are all the questions coming up on this
00:00:40 --> 00:00:42 episode of space nuts.
00:00:42 --> 00:00:45 Voice Over Guy: 15 seconds. Guidance is internal.
00:00:45 --> 00:00:48 10, 9, ignition
00:00:48 --> 00:00:51 sequence time. Uh, space nuts. 5, 4, 3,
00:00:51 --> 00:00:54 2. 1. 2, 3, 4, 5, 5, 4,
00:00:54 --> 00:00:57 3, 2, 1. Space nuts. Astronauts
00:00:57 --> 00:00:58 report it feels good.
00:00:59 --> 00:01:01 Andrew Dunkley: And Fred Watson Watson is with us again to
00:01:01 --> 00:01:03 solve all these little riddles.
00:01:03 --> 00:01:05 Professor Fred Watson: Hello, Fred Watson. Hello Andrew. Nice to,
00:01:05 --> 00:01:06 um, help you solve the riddles.
00:01:08 --> 00:01:10 Andrew Dunkley: Uh, I don't know anything.
00:01:11 --> 00:01:12 That's why I bring you along.
00:01:12 --> 00:01:14 Professor Fred Watson: Oh, good. Well, I'm about to be of assistant.
00:01:14 --> 00:01:16 Andrew Dunkley: Makes it so much more interesting when
00:01:16 --> 00:01:18 there's two people talking. Monologues are
00:01:18 --> 00:01:20 just so boring, don't you reckon?
00:01:23 --> 00:01:25 Unless it's a super interesting person like
00:01:25 --> 00:01:26 yourself. Right.
00:01:26 --> 00:01:28 Professor Fred Watson: No, I'm, I'm capable of boring the pants off
00:01:28 --> 00:01:31 people as, uh, people have assured me before.
00:01:31 --> 00:01:33 So that's all right.
00:01:34 --> 00:01:37 Andrew Dunkley: So we've got a lot to get through and uh,
00:01:37 --> 00:01:40 it's, it's even trickier this week because we
00:01:40 --> 00:01:43 do have a technical, uh, issue, which means
00:01:43 --> 00:01:44 you are going to have to lip ring.
00:01:46 --> 00:01:48 Professor Fred Watson: Okay. Uh,
00:01:49 --> 00:01:51 so. Right. I'll do my best.
00:01:51 --> 00:01:52 Andrew Dunkley: We'll see how that.
00:01:52 --> 00:01:54 Professor Fred Watson: I'm wondering where the lips are going to be.
00:01:54 --> 00:01:55 That's the only thing.
00:01:55 --> 00:01:57 Andrew Dunkley: Yes, yes. Well, the first set of lips come
00:01:57 --> 00:02:00 from Paul. Uh, so let's hear his question.
00:02:00 --> 00:02:03 Paul: G' day, Fred Watson, Andrew, Johnty,
00:02:03 --> 00:02:06 Heidi, whoever happens to be at the helm. Uh,
00:02:06 --> 00:02:08 this is Paul from Sunnybris, Vegas. Thanks,
00:02:08 --> 00:02:10 uh, for doing a great job as always.
00:02:10 --> 00:02:13 I have a quick question about surprise
00:02:13 --> 00:02:16 black holes. Um, Dr. Shamir
00:02:16 --> 00:02:17 put out a paper recently about
00:02:19 --> 00:02:22 his ideas regarding the fact that, uh,
00:02:22 --> 00:02:25 some galaxies are spinning one way and
00:02:25 --> 00:02:26 uh, a lot of them, most of them the other
00:02:26 --> 00:02:29 way. And another fellow chipped in,
00:02:29 --> 00:02:32 Nikodem Poplowski from New
00:02:32 --> 00:02:34 Haven, suggested that maybe that was because
00:02:34 --> 00:02:36 our universe was born inside a black hole.
00:02:37 --> 00:02:40 If that is true, how the heck did we get
00:02:40 --> 00:02:42 out? And if we didn't get
00:02:42 --> 00:02:45 out and we're still inside, then
00:02:46 --> 00:02:48 how is that possible given that, you know,
00:02:48 --> 00:02:50 anything that goes inside a black hole, uh,
00:02:51 --> 00:02:53 is spaghettified according to our current
00:02:53 --> 00:02:56 thinking and therefore incoherent. I mean I
00:02:56 --> 00:02:59 know I'm incoherent, but you know what I'm
00:02:59 --> 00:03:00 talking about. Talking about when it comes to
00:03:00 --> 00:03:02 ordinary baryonic matter. Uh,
00:03:03 --> 00:03:05 love to get your thoughts on this.
00:03:06 --> 00:03:09 Anyway, uh, keep up the good work and
00:03:09 --> 00:03:11 catch us later. Cheers.
00:03:11 --> 00:03:13 Andrew Dunkley: Thank you Paul and hope all is well in
00:03:13 --> 00:03:16 Brisbane. Paul is asking about the universe
00:03:16 --> 00:03:19 being born inside a black hole. How do
00:03:19 --> 00:03:21 we get out? And why don't we get
00:03:21 --> 00:03:23 spaghettified as a consequence of that?
00:03:24 --> 00:03:27 Amongst many other things. But uh, that was
00:03:27 --> 00:03:28 the basis of the question.
00:03:28 --> 00:03:31 Professor Fred Watson: So. Yes. So as you've already uh, mentioned,
00:03:31 --> 00:03:33 I didn't hear any of Paul's question there.
00:03:33 --> 00:03:36 Not at all. However, I did listen uh, to it
00:03:36 --> 00:03:38 yesterday. So I've got a bit of an idea of
00:03:38 --> 00:03:40 what Paul was suggesting. The fact that um,
00:03:41 --> 00:03:43 we have uh, new
00:03:43 --> 00:03:46 observations which uh, have been made with
00:03:46 --> 00:03:48 the James Webb Space Telescope,
00:03:49 --> 00:03:51 uh, that um, are
00:03:51 --> 00:03:54 intriguing in the sense that uh,
00:03:54 --> 00:03:57 these scientists, uh, and they
00:03:57 --> 00:04:00 are basically uh, mostly
00:04:00 --> 00:04:01 located at Kansas State University.
00:04:03 --> 00:04:06 Uh, the, the rotation of galaxies in the
00:04:06 --> 00:04:08 deep universe isn't random. Uh,
00:04:08 --> 00:04:11 you'd expect, you know, galaxies to
00:04:11 --> 00:04:13 be rotating in.
00:04:14 --> 00:04:16 They can only go one way or the other. But
00:04:16 --> 00:04:19 you would expect an equal balance of
00:04:19 --> 00:04:22 rotations. Uh, and uh,
00:04:22 --> 00:04:25 what find, uh, or what these scientists
00:04:25 --> 00:04:28 find at Kansas State University using
00:04:28 --> 00:04:31 the James Webb Space Telescope
00:04:31 --> 00:04:33 Advanced Deep Extra galactic survey or
00:04:33 --> 00:04:36 jades, um, what they find is out of
00:04:36 --> 00:04:38 263 galaxies,
00:04:39 --> 00:04:42 um, which you know, which
00:04:43 --> 00:04:45 give away their rotation because we know that
00:04:45 --> 00:04:47 spiral arms nearly always trail. There's at
00:04:47 --> 00:04:49 least one galaxy where the spiral arms are
00:04:49 --> 00:04:51 leading but most of them trail.
00:04:52 --> 00:04:55 And what they find is that out of these 263
00:04:55 --> 00:04:57 galaxies, about two thirds of them
00:04:57 --> 00:05:00 are going clockwise and the rest are going
00:05:00 --> 00:05:03 anticlockwise. And that is an imbalance.
00:05:03 --> 00:05:05 That's a statistically significant imbalance,
00:05:06 --> 00:05:08 uh, that suggests that something's going on
00:05:08 --> 00:05:11 that we don't understand and that
00:05:11 --> 00:05:14 leads to the possibility that
00:05:14 --> 00:05:17 perhaps the universe itself is
00:05:17 --> 00:05:20 rotating. Um, and I've seen
00:05:20 --> 00:05:23 other um, papers um, on
00:05:23 --> 00:05:25 this topic that suggest that maybe the
00:05:25 --> 00:05:27 universe rotates once in every 500 billion
00:05:27 --> 00:05:30 years. That's one figure that I've seen
00:05:31 --> 00:05:33 now, um, a consequence of the
00:05:33 --> 00:05:36 rotating universe. And I think this is where
00:05:36 --> 00:05:38 Paul's question went. I'm trying to remember
00:05:38 --> 00:05:41 having heard it yesterday, uh, is that
00:05:42 --> 00:05:45 it lend some weight to the
00:05:45 --> 00:05:48 idea that the universe is
00:05:48 --> 00:05:51 inside a black hole. Uh, in other
00:05:51 --> 00:05:54 Words that there is an event horizon at some
00:05:54 --> 00:05:56 huge distance from where we are,
00:05:57 --> 00:05:59 uh, and we are all within this
00:05:59 --> 00:06:02 black hole. Um,
00:06:03 --> 00:06:05 what does that mean for observational
00:06:05 --> 00:06:08 cosmology? I suspect it's going to be very
00:06:08 --> 00:06:11 difficult for us to confirm
00:06:11 --> 00:06:13 that ever. Uh, and I
00:06:13 --> 00:06:16 think, um, you know, this is
00:06:16 --> 00:06:19 speculative research. It's important
00:06:19 --> 00:06:21 research because you, you, you want to know
00:06:21 --> 00:06:24 um, how some of these things interact. And I
00:06:24 --> 00:06:25 might just mention, and I think we've
00:06:25 --> 00:06:28 discussed this before, Andrew, on space nuts,
00:06:28 --> 00:06:31 that the idea of a rotating universe actually
00:06:31 --> 00:06:34 relieves some of the issues, uh, that
00:06:34 --> 00:06:37 we find uh, in observing the universe. One of
00:06:37 --> 00:06:38 them is the Hubble tension. And I know
00:06:38 --> 00:06:41 there's a question coming up about that. Um,
00:06:41 --> 00:06:43 so a rotating universe has certainly
00:06:43 --> 00:06:45 attractive possibilities, but we absolutely
00:06:45 --> 00:06:48 don't know whether it is a rotating universe
00:06:48 --> 00:06:50 and indeed whether that means that we're
00:06:50 --> 00:06:52 inside a black hole. Uh, so what I was going
00:06:52 --> 00:06:54 to say was the idea of a universe within a
00:06:54 --> 00:06:56 black hole is akin to the idea of
00:06:56 --> 00:06:59 multiverses. The idea that um,
00:06:59 --> 00:07:02 um, multiple universes exist and we
00:07:02 --> 00:07:04 are just one of them. I'm not really, I
00:07:04 --> 00:07:07 don't think giving a sensible answer to
00:07:07 --> 00:07:08 Paul's question, partly because I couldn't
00:07:08 --> 00:07:11 hear it. But I think he was basically asking,
00:07:11 --> 00:07:13 you know, what happens? How does it happen?
00:07:14 --> 00:07:16 Uh, how are we not being spaghettified?
00:07:16 --> 00:07:19 That's because, uh, I can tell you the answer
00:07:19 --> 00:07:21 to that. Uh, we're not in a region, um,
00:07:22 --> 00:07:24 of the black hole where the um,
00:07:26 --> 00:07:29 gravitational pull is
00:07:29 --> 00:07:32 changing very, very rapidly with space.
00:07:33 --> 00:07:34 And that's what makes a black hole
00:07:34 --> 00:07:37 spaghettify. You, you go from one point to
00:07:37 --> 00:07:39 another and your gravitational pull is very
00:07:39 --> 00:07:40 different. So your head feels a different
00:07:40 --> 00:07:42 gravity from your feet and you get
00:07:42 --> 00:07:45 spaghettified. We're not in a place where
00:07:45 --> 00:07:47 that would be happening if we were inside a
00:07:47 --> 00:07:50 black hole. But uh, you know, all bets are
00:07:50 --> 00:07:53 off because inside a black hole, uh, there
00:07:53 --> 00:07:55 might. We're in a different dimensional
00:07:55 --> 00:07:57 space. A black hole is a singularity. Are,
00:07:57 --> 00:07:59 ah, we in a singularity? A singularity is a
00:07:59 --> 00:08:02 point with no dimensions. Work that one
00:08:02 --> 00:08:05 out. So we'd have to be almost in a different
00:08:05 --> 00:08:07 dimensional space. So it's an interesting
00:08:07 --> 00:08:10 question, um, to which I don't
00:08:10 --> 00:08:12 think anybody knows the answer, but there are
00:08:12 --> 00:08:14 a few people who are probably thinking
00:08:14 --> 00:08:16 through it a lot more clearly than I am.
00:08:17 --> 00:08:19 Andrew Dunkley: Well, Paul mentioned uh, a physicist by the
00:08:19 --> 00:08:22 name of Nicodem, um, Poplaus,
00:08:22 --> 00:08:25 uh, he's one that's put this theory
00:08:25 --> 00:08:27 forward that um, our
00:08:28 --> 00:08:30 observable universe is not just a part of a
00:08:30 --> 00:08:33 larger universe, but is in fact the interior
00:08:33 --> 00:08:36 of a black hole within a larger context.
00:08:36 --> 00:08:38 Professor Fred Watson: Yes. So you've got extra dimensions somewhere
00:08:38 --> 00:08:40 out there within, uh, which we exist.
00:08:41 --> 00:08:44 Uh, that's right. It's, um, uh,
00:08:44 --> 00:08:47 you know, I, I, Yes, I remember, um, checking
00:08:47 --> 00:08:49 out the, the researchers that, uh, that Paul
00:08:49 --> 00:08:51 mentioned yesterday when I looked at it. Uh,
00:08:51 --> 00:08:53 it's interesting stuff. Yeah.
00:08:54 --> 00:08:56 Andrew Dunkley: What do you think, personally? I mean, is
00:08:56 --> 00:08:58 there any possibility that this could be
00:08:59 --> 00:09:00 real?
00:09:00 --> 00:09:03 Professor Fred Watson: Um, to me it's on the same level
00:09:03 --> 00:09:05 as does heaven exist? Uh, you know,
00:09:06 --> 00:09:09 it's questions to which we really can't
00:09:09 --> 00:09:12 find answers. We can theorise, we can
00:09:12 --> 00:09:14 conjecture, we can speculate, we can write
00:09:14 --> 00:09:17 equations down. And probably some of the
00:09:17 --> 00:09:19 equations do support the idea that we're
00:09:19 --> 00:09:21 within an event horizon. It goes back a very
00:09:21 --> 00:09:24 long way. It's not a new idea at all. Um,
00:09:24 --> 00:09:27 but, um, I mean, people have put new numbers
00:09:27 --> 00:09:30 on it, I think, and, um, new observations. I
00:09:30 --> 00:09:32 think we, we watch this space. Next time this
00:09:32 --> 00:09:34 question comes up, I might be able to hear it
00:09:34 --> 00:09:35 properly and might be able to give a more
00:09:35 --> 00:09:37 cogent answer.
00:09:38 --> 00:09:40 Andrew Dunkley: Yes, indeed. I'll be working on that
00:09:40 --> 00:09:41 technicality.
00:09:41 --> 00:09:42 Professor Fred Watson: I don't, I'm sure it's not your fault,
00:09:42 --> 00:09:44 Andrew. I know what these gremlins are like.
00:09:44 --> 00:09:45 We get them all the time.
00:09:46 --> 00:09:49 Andrew Dunkley: Yeah, I'll blame the equipment. Never ever,
00:09:49 --> 00:09:49 though.
00:09:49 --> 00:09:51 Professor Fred Watson: Never the place. New Z. No, that's true.
00:09:54 --> 00:09:55 Andrew Dunkley: Thank you, Paul. Hope we covered that
00:09:55 --> 00:09:58 adequately, as we strive to do here on Space
00:09:58 --> 00:09:58 Nuts.
00:10:03 --> 00:10:04 Professor Fred Watson: Space Nuts.
00:10:04 --> 00:10:06 Andrew Dunkley: Uh, our next question, Fred Watson, comes
00:10:06 --> 00:10:09 from Casey in Colorado. In fact, he has
00:10:09 --> 00:10:11 two. Could you please explain the new
00:10:11 --> 00:10:14 theory of gravity in simple terms?
00:10:15 --> 00:10:17 Does it, uh, have any merit? And could you,
00:10:17 --> 00:10:20 uh, please explain hubble tension and what it
00:10:20 --> 00:10:22 means for our understanding of the universe?
00:10:23 --> 00:10:26 Professor Fred Watson: Yes. Uh, so
00:10:26 --> 00:10:28 that's the answer. The answer is yes. Yes, I
00:10:28 --> 00:10:31 can. The new
00:10:31 --> 00:10:33 theory of gravity, which I like very much.
00:10:34 --> 00:10:36 Um, this comes from scientists in Finland,
00:10:36 --> 00:10:38 which is a place that I like very much as
00:10:38 --> 00:10:41 well. Um, and it's
00:10:41 --> 00:10:44 what they've done, you know, they've
00:10:44 --> 00:10:46 taken, um, a step
00:10:46 --> 00:10:49 forward. And I'm assuming
00:10:49 --> 00:10:52 this is the, uh, this is indeed
00:10:52 --> 00:10:55 the, um, the, uh, the, the
00:10:55 --> 00:10:57 new theory that case is speaking about,
00:10:57 --> 00:11:00 because we get nearly one every week, a new
00:11:00 --> 00:11:02 theory of gravity. But this is the latest
00:11:02 --> 00:11:04 one. Um, it's, uh, as I said,
00:11:04 --> 00:11:07 it's from, uh, it's from, uh, Finnish
00:11:07 --> 00:11:09 scientists, uh, at Aalto, uh,
00:11:10 --> 00:11:11 University. Um,
00:11:13 --> 00:11:15 so it's what they've done
00:11:16 --> 00:11:18 is what Einstein tried to do for the last,
00:11:18 --> 00:11:21 for 30 years of his life. Uh,
00:11:21 --> 00:11:24 which is to unify quantum
00:11:24 --> 00:11:26 field theory and relativity.
00:11:27 --> 00:11:30 And uh, that's an issue because uh, they
00:11:30 --> 00:11:33 are incompatible at ah, the levels that we
00:11:33 --> 00:11:36 try and look at them now. Um,
00:11:36 --> 00:11:39 and so uh, to bring a
00:11:39 --> 00:11:41 quantum theory of gravity into being
00:11:42 --> 00:11:45 is a big step. So um, what do I
00:11:45 --> 00:11:47 mean by, by bringing a theory into being?
00:11:47 --> 00:11:49 Well we know that there are four
00:11:49 --> 00:11:52 fundamental forces in nature. Uh,
00:11:52 --> 00:11:55 the strong and weak nuclear forces,
00:11:55 --> 00:11:58 electromagnetism and gravity. And the
00:11:58 --> 00:12:01 first three of those have very,
00:12:01 --> 00:12:04 very well established and well uh,
00:12:04 --> 00:12:07 understood quantum theories. Um,
00:12:07 --> 00:12:09 for example, we know that electromagnetism is
00:12:09 --> 00:12:11 propagated by photons. We're talking about it
00:12:11 --> 00:12:13 all the time. So the suspicion is that
00:12:14 --> 00:12:16 gravity uh, is propagated by gravitons. But
00:12:16 --> 00:12:18 so far there's been no theory of what
00:12:18 --> 00:12:20 gravitons might be like. So what these
00:12:20 --> 00:12:23 scientists have done have developed
00:12:23 --> 00:12:26 a new theory, uh, a new quantum theory of
00:12:26 --> 00:12:28 gravity. Uh, and I'm actually going to once
00:12:28 --> 00:12:31 again ah, quote from phys.org, very uh,
00:12:31 --> 00:12:34 nice account of this, um, uh,
00:12:34 --> 00:12:37 which is actually, I think it is part of the
00:12:37 --> 00:12:39 press release from Aalto University in
00:12:39 --> 00:12:41 Finland. So I'm quoting the university.
00:12:42 --> 00:12:44 Um, researchers at Aalto University have
00:12:44 --> 00:12:46 developed a new theory, quantum theory of
00:12:46 --> 00:12:48 gravity, which describes gravity in a way
00:12:48 --> 00:12:51 that is compatible with the standard model
00:12:51 --> 00:12:54 of particle physics, opening the door to an
00:12:54 --> 00:12:56 improved understanding of how the universe
00:12:56 --> 00:12:58 began. While the world of
00:12:59 --> 00:13:02 uh, quant theoretical physics may seem
00:13:02 --> 00:13:04 remote from applicable tech, the findings are
00:13:04 --> 00:13:06 remarkable. Modern technology is built on
00:13:06 --> 00:13:08 such fundamental advances. For example the
00:13:08 --> 00:13:10 GPS in your smartphone works thanks to
00:13:10 --> 00:13:13 Einstein's theory of gravity. Uh, and then
00:13:13 --> 00:13:16 uh, the article goes on to describe
00:13:16 --> 00:13:19 the theory is published in uh, Research
00:13:19 --> 00:13:22 Reports on Progress in Physics. Um,
00:13:22 --> 00:13:25 and this is the quote that I wanted to make.
00:13:25 --> 00:13:27 This comes from the lead uh, author of the
00:13:27 --> 00:13:30 paper. Uh, and um,
00:13:31 --> 00:13:34 um, basically they um,
00:13:38 --> 00:13:40 they've got lovely Finnish names. That's why
00:13:40 --> 00:13:42 I'm stumbling. It's Mikko Partanen,
00:13:43 --> 00:13:46 uh, who's the um, lead author. Uh,
00:13:46 --> 00:13:48 and the quote is as
00:13:49 --> 00:13:51 follows. And this kind of puts
00:13:51 --> 00:13:54 it into perspective, if that's the big
00:13:54 --> 00:13:57 word. If this turns out to lead to a
00:13:57 --> 00:14:00 complete quantum field theory of gravity,
00:14:00 --> 00:14:02 then eventually it will give answers to the
00:14:02 --> 00:14:04 very difficult problems of understanding
00:14:05 --> 00:14:07 singularities in black hole and black holes
00:14:07 --> 00:14:10 and the Big Bang. A theory uh,
00:14:10 --> 00:14:13 that coherently describes all fundamental
00:14:13 --> 00:14:15 forces of nature is often called the Theory
00:14:15 --> 00:14:18 of Everything. Uh, some fundamental
00:14:18 --> 00:14:20 questions of physics still remain unanswered.
00:14:20 --> 00:14:22 For example, the present theories do not yet
00:14:22 --> 00:14:24 explain why there is more matter than
00:14:24 --> 00:14:26 antimatter in the observable universe. Uh,
00:14:26 --> 00:14:28 and what they've done is, um, they've
00:14:28 --> 00:14:30 developed something called a gauge theory.
00:14:30 --> 00:14:32 And gauge theories are a particular kind of
00:14:32 --> 00:14:35 theory about the way particles interact with
00:14:35 --> 00:14:37 each other through a field. Ah, like the
00:14:37 --> 00:14:39 Higgs field and the Higgs boson. Um,
00:14:40 --> 00:14:43 so, uh, it's basically a
00:14:43 --> 00:14:46 very nice a, ah, very nice account. I won't
00:14:46 --> 00:14:48 read any more because, you know, gauge
00:14:48 --> 00:14:50 theories got symmetries and things of that
00:14:50 --> 00:14:53 sort. Um, it's,
00:14:54 --> 00:14:57 um, a nice account. I recommend people have a
00:14:57 --> 00:14:59 look@the phys.org uh, paper.
00:15:00 --> 00:15:02 Uh, uh, sorry, the fizz.org article.
00:15:03 --> 00:15:05 Casey, I'd send you to that as well to have a
00:15:05 --> 00:15:07 look. It's a very nice account of, of what's
00:15:07 --> 00:15:09 happening. You may end up like me thinking I
00:15:09 --> 00:15:11 really need to know a bit more about gauge
00:15:11 --> 00:15:13 theory before I can understand this. Uh,
00:15:14 --> 00:15:16 but, uh, nevertheless, you'll get, um, a good
00:15:16 --> 00:15:18 idea of what's going on, I think.
00:15:19 --> 00:15:20 Andrew Dunkley: M. Okay.
00:15:20 --> 00:15:22 Now, Casey also wanted you to
00:15:23 --> 00:15:25 explain, if you could, Hubble tension.
00:15:25 --> 00:15:27 Professor Fred Watson: Yeah, that's an easier one. And, uh, as we've
00:15:27 --> 00:15:28 spoken about.
00:15:28 --> 00:15:29 Andrew Dunkley: That's good.
00:15:29 --> 00:15:31 Professor Fred Watson: As we've spoken about today, uh, that's one
00:15:31 --> 00:15:33 of the things we might get rid of. Yes,
00:15:33 --> 00:15:35 Hubble tension is a lot easier than gauge
00:15:35 --> 00:15:37 theory. Um, and what it amounts to is we've
00:15:37 --> 00:15:40 got two ways of calculating
00:15:40 --> 00:15:43 the current expansion of the universe.
00:15:44 --> 00:15:46 Uh, one is by looking at
00:15:47 --> 00:15:49 galaxies in our
00:15:49 --> 00:15:52 vicinity, uh, and looking at the rate at
00:15:52 --> 00:15:54 which they are speeding away from us.
00:15:55 --> 00:15:57 They're moving away from us faster as their
00:15:57 --> 00:15:59 distance increases. This is exactly the
00:15:59 --> 00:16:01 discovery that hubble made in 1929.
00:16:02 --> 00:16:04 And, uh, gives us something we call the
00:16:04 --> 00:16:07 Hubble constant, which is just the rate of
00:16:07 --> 00:16:09 expansion of the universe. Today we call it,
00:16:09 --> 00:16:12 ah, h. Naught, um, Hubble
00:16:12 --> 00:16:15 zero, which is the expansion rate today.
00:16:16 --> 00:16:18 Now, you can also get an idea of that
00:16:18 --> 00:16:21 or a measurement of it from the cosmic
00:16:21 --> 00:16:24 microwave background radiation. And that, to
00:16:24 --> 00:16:26 recap, is the flash of the Big Bang. We're
00:16:26 --> 00:16:28 looking back so far in time. We're seeing
00:16:28 --> 00:16:30 back to a time 380 years after the Big
00:16:30 --> 00:16:32 Bang, when the universe was still opaque and
00:16:32 --> 00:16:35 glowing brightly. So we see this wall of
00:16:35 --> 00:16:37 radiation which is now in the microwave
00:16:37 --> 00:16:40 region of the spectrum, uh, and it's
00:16:40 --> 00:16:43 peppered with a pattern of
00:16:43 --> 00:16:46 warmer and cooler places, uh,
00:16:46 --> 00:16:49 and those, uh, zones of higher
00:16:49 --> 00:16:51 and lower temperature, and it's only by a
00:16:51 --> 00:16:54 tiny fraction, uh, they correspond to
00:16:54 --> 00:16:57 the structure in that fireball. Um,
00:16:57 --> 00:17:00 in fact, it's caused by sound waves moving
00:17:00 --> 00:17:02 through it, they're called baryonic acoustic
00:17:02 --> 00:17:04 oscillations. And we can, by measuring the
00:17:04 --> 00:17:07 properties of that peppering of warmer and
00:17:07 --> 00:17:10 cooler regions, we can actually work
00:17:10 --> 00:17:13 out what the expansion of the universe is
00:17:13 --> 00:17:15 today. And it turns out that the two
00:17:15 --> 00:17:18 figures are different, um, by something
00:17:18 --> 00:17:21 like 4 or 5%.
00:17:21 --> 00:17:24 And that in modern terms is big
00:17:24 --> 00:17:27 enough to worry about. It's not just an error
00:17:27 --> 00:17:30 of measurement. Uh, these have got fairly
00:17:30 --> 00:17:32 tight limits on the uncertainties, but
00:17:32 --> 00:17:34 they're different. And that is the Hubble
00:17:34 --> 00:17:36 tension. Hm.
00:17:36 --> 00:17:38 Andrew Dunkley: But didn't they recently, recently
00:17:39 --> 00:17:41 release a paper that suggested that the
00:17:41 --> 00:17:44 variations are actually within a normal
00:17:44 --> 00:17:46 range? That this, this,
00:17:48 --> 00:17:51 these two figures that don't match are, ah,
00:17:51 --> 00:17:51 close enough?
00:17:51 --> 00:17:52 Professor Fred Watson: Well, yes.
00:17:52 --> 00:17:53 Andrew Dunkley: Didn't we talk?
00:17:53 --> 00:17:55 Professor Fred Watson: We did that. Um, some people have suggested
00:17:55 --> 00:17:57 that, that it is, that it is actually within
00:17:57 --> 00:18:00 the experimental uncertainty, but it's
00:18:00 --> 00:18:02 still seen as attention. They could, they
00:18:02 --> 00:18:04 should be nearer than what they are.
00:18:05 --> 00:18:08 Andrew Dunkley: Yeah, okay. Very, very interesting,
00:18:08 --> 00:18:09 Casey. Thanks for both your questions. And
00:18:09 --> 00:18:12 no, you haven't spammed us. Two questions
00:18:12 --> 00:18:14 doesn't equal spam. There's
00:18:14 --> 00:18:16 probably a definition somewhere online that
00:18:16 --> 00:18:19 says how many, how many emails become spam.
00:18:20 --> 00:18:22 You're well, well outside that tolerance. So
00:18:22 --> 00:18:25 no problem there. Uh, this is Space
00:18:25 --> 00:18:28 Nuts Q A edition with Andrew Dunkley and
00:18:28 --> 00:18:29 Professor Fred Watson Watson.
00:18:34 --> 00:18:37 Space Nuts. Okay, Fred Watson, let's uh, move
00:18:37 --> 00:18:39 on to our next question. It's an audio
00:18:39 --> 00:18:41 question so you won't be able to hear it, but
00:18:42 --> 00:18:44 it comes from Simon.
00:18:45 --> 00:18:47 Simon: Hi, it's uh, Simon from Vasey in
00:18:48 --> 00:18:50 New South Wales here. Uh, my question's
00:18:50 --> 00:18:53 around, uh, the search for Planet Nine,
00:18:55 --> 00:18:58 uh, other exoplanets. Ah, few have been found
00:18:58 --> 00:19:01 using radial velocity methods. Is
00:19:01 --> 00:19:03 that something we could do with the sun?
00:19:04 --> 00:19:07 Um, I guess Planet nine being so far
00:19:07 --> 00:19:09 out, probably wouldn't have much influence,
00:19:10 --> 00:19:13 but we would have so much data on the
00:19:13 --> 00:19:15 sun as well
00:19:16 --> 00:19:19 that it might be easy to suss out.
00:19:19 --> 00:19:21 Anyway, Ah, that's my question.
00:19:23 --> 00:19:26 Andrew Dunkley: Thank you, Simon. Good to hear from you. Hope
00:19:26 --> 00:19:28 all is well in Veyce in New South Wales. Uh,
00:19:29 --> 00:19:31 he's asking, in the search for Planet nine,
00:19:32 --> 00:19:35 um, we've used the radial velocity method,
00:19:35 --> 00:19:38 uh, in the past to find other objects. Could,
00:19:38 --> 00:19:41 uh, we use the sun in the
00:19:41 --> 00:19:42 search for Planet Nine?
00:19:42 --> 00:19:45 Professor Fred Watson: Yeah, and it's a great question. Uh, I'm
00:19:45 --> 00:19:47 very well posed, Simon. Uh, I did actually
00:19:47 --> 00:19:49 manage to hear that through my own, um,
00:19:50 --> 00:19:52 recording, which I found and listened back
00:19:52 --> 00:19:54 to. So I know what Simon asked.
00:19:56 --> 00:19:58 And what he's saying is
00:19:59 --> 00:20:00 that we know that when we look for
00:20:00 --> 00:20:03 exoplanets, planets around, uh, other
00:20:03 --> 00:20:05 stars. What we look for is the change in
00:20:05 --> 00:20:08 position of the star itself as it's
00:20:08 --> 00:20:10 pulled one way and another by the planet
00:20:10 --> 00:20:13 orbiting around it. And yes,
00:20:13 --> 00:20:15 indeed, the solar system, uh,
00:20:16 --> 00:20:18 has such an effect. So Jupiter
00:20:18 --> 00:20:21 principally is the main planet that's
00:20:22 --> 00:20:24 pulling the sun's centre one way or the
00:20:24 --> 00:20:26 other. Uh, but the other planets all
00:20:27 --> 00:20:30 intervene as well. And so what we
00:20:30 --> 00:20:32 have is something that's called the solar
00:20:32 --> 00:20:35 system's barycenter, the centre of mass
00:20:35 --> 00:20:38 of the solar system and that moves as the
00:20:38 --> 00:20:41 planets wander around. And,
00:20:42 --> 00:20:44 um, we've exactly as, um,
00:20:45 --> 00:20:48 Simon says, we've managed
00:20:48 --> 00:20:50 to work out the position of the
00:20:50 --> 00:20:53 barycenter very, very accurately,
00:20:53 --> 00:20:56 uh, partly because we know where the planets
00:20:56 --> 00:20:58 are and things of that sort of. Now,
00:20:59 --> 00:21:02 Simon's question is
00:21:02 --> 00:21:05 actually exactly the same as a
00:21:05 --> 00:21:07 question that I found on Stack Exchange
00:21:07 --> 00:21:10 Online. The question was, wow, can
00:21:10 --> 00:21:13 the paper narrowing the solar system's
00:21:13 --> 00:21:16 barycenter to within 100 metres help
00:21:16 --> 00:21:19 find Planet Nine? Uh,
00:21:19 --> 00:21:21 so that's basically what Simon asked. And the
00:21:21 --> 00:21:24 bottom line, there's a long, long set
00:21:24 --> 00:21:27 of calculations here which I won't go
00:21:27 --> 00:21:29 through, but the answer is probably
00:21:29 --> 00:21:32 not. Um, uh, it's because
00:21:32 --> 00:21:35 the Planet
00:21:35 --> 00:21:37 nine's influence on the solar system's
00:21:37 --> 00:21:40 barycenter, it's helped by the fact that
00:21:40 --> 00:21:42 Planet nine's a long way away. Um,
00:21:42 --> 00:21:45 um, so it's got sort of leverage, uh, as it
00:21:45 --> 00:21:48 goes around. Um, um,
00:21:49 --> 00:21:51 the short answer is
00:21:52 --> 00:21:55 maybe we could do it, but we wouldn't be
00:21:55 --> 00:21:58 able to do it without hundreds, if not
00:21:58 --> 00:22:01 thousands of years of precise data. And
00:22:01 --> 00:22:03 that's because Planet nine is probably
00:22:03 --> 00:22:06 orbiting the sun on that kind of timescale.
00:22:07 --> 00:22:09 And so you don't see any, you know, what
00:22:09 --> 00:22:11 you'd be looking for is,
00:22:11 --> 00:22:13 um, changes in the position of the
00:22:13 --> 00:22:16 barycenter, which are not caused by the known
00:22:16 --> 00:22:19 planets. But it'll take you
00:22:19 --> 00:22:21 hundreds or thousands of years to see that
00:22:21 --> 00:22:24 because of the great distance that Planet
00:22:24 --> 00:22:27 nine is at. So the answer is probably
00:22:27 --> 00:22:29 not, but it's a great question and really
00:22:29 --> 00:22:31 nice thinking. I like Simon's thinking there.
00:22:32 --> 00:22:35 Andrew Dunkley: Yeah, yeah, it's quite astute. Uh, the
00:22:35 --> 00:22:38 other factor that comes into play here is
00:22:38 --> 00:22:41 the new theory that Planet nine doesn't
00:22:41 --> 00:22:43 exist because there's another planet even
00:22:43 --> 00:22:46 further out that, uh, has
00:22:46 --> 00:22:49 only just been sort of put into, um,
00:22:49 --> 00:22:52 a pager and open for discussion. So we
00:22:52 --> 00:22:54 only talked about that last week. So the
00:22:54 --> 00:22:57 search for Planet nine might be a forlorn
00:22:57 --> 00:22:59 hope anyway, uh, um, because it
00:22:59 --> 00:23:02 probably, according to the new theory that's
00:23:02 --> 00:23:03 correct.
00:23:03 --> 00:23:05 Professor Fred Watson: Yeah. Now, the new theory is based more on
00:23:05 --> 00:23:07 observations than theory because it's two
00:23:08 --> 00:23:10 observations separated by something like 30
00:23:10 --> 00:23:12 years that seem to show something moving very
00:23:12 --> 00:23:14 slowly in the outer solar system.
00:23:15 --> 00:23:17 You can bet your life will do more observing
00:23:17 --> 00:23:19 of that over, uh, uh, coming
00:23:20 --> 00:23:23 decades. Uh, and maybe that will turn out to
00:23:23 --> 00:23:24 be what I think is being called Planet eight
00:23:24 --> 00:23:26 and a half at the moment, because nobody
00:23:26 --> 00:23:28 really knows whether it's there or not. But
00:23:28 --> 00:23:31 as you said, if that is real, it rules out
00:23:31 --> 00:23:33 Planet nine. The two can't exist together.
00:23:35 --> 00:23:37 Andrew Dunkley: Exactly right. All right, there you go,
00:23:37 --> 00:23:40 Simon. Um, we'll see where that, uh,
00:23:40 --> 00:23:41 ends up, but it might take a while.
00:23:42 --> 00:23:45 Uh, final question comes from Joe
00:23:45 --> 00:23:47 in Olala in Washington. I hope I pronounced
00:23:47 --> 00:23:50 that correctly. Is there an upper limit to
00:23:50 --> 00:23:53 how much Delta V, uh, that can be
00:23:53 --> 00:23:55 practically generated by gravitational
00:23:55 --> 00:23:57 assists? Is it possible to develop
00:23:58 --> 00:24:00 sufficient Delta V for timely interstellar
00:24:00 --> 00:24:03 travel by winding up a probe in our solar
00:24:03 --> 00:24:06 system before launching it, uh, to a nearby
00:24:06 --> 00:24:09 star? Uh, thanks for all that you do. Cheers,
00:24:09 --> 00:24:11 Joe. Now, Delta V, that is the impulse per
00:24:11 --> 00:24:14 unit of spacecraft mass, yes?
00:24:15 --> 00:24:17 Professor Fred Watson: Well, it's basically the change in velocity.
00:24:19 --> 00:24:21 Um, yes. And impulse is the, uh, that's the
00:24:21 --> 00:24:24 way people talk about these Delta V's in
00:24:24 --> 00:24:27 this, in the rocket industry. It's all rocket
00:24:27 --> 00:24:29 science. What is it anyway, Delta V, uh,
00:24:30 --> 00:24:32 I think in Joe's context here is
00:24:33 --> 00:24:35 how much velocity increase you can get
00:24:35 --> 00:24:38 from a gravity assist, from a, ah,
00:24:38 --> 00:24:41 slingshot. Uh, and the answer is
00:24:41 --> 00:24:44 probably no, um, in terms of trying to wind
00:24:44 --> 00:24:46 up, you know, the speed of things so that
00:24:46 --> 00:24:49 you, you know, you tell something out of the
00:24:49 --> 00:24:52 solar system at 10th, uh, the
00:24:52 --> 00:24:55 speed of light or something like that. Um,
00:24:55 --> 00:24:58 the reading that I've done on this, and I did
00:24:58 --> 00:25:00 check it out seems, uh, to suggest,
00:25:01 --> 00:25:04 excuse me, that um, we are probably
00:25:05 --> 00:25:07 limited to,
00:25:08 --> 00:25:11 um, the sorts of velocities that we
00:25:11 --> 00:25:14 see among the planets of the solar
00:25:14 --> 00:25:16 system. Now remember, the Earth is orbiting
00:25:16 --> 00:25:19 the sun at 30 kilometres per second.
00:25:20 --> 00:25:23 Um, and, um, those velocities
00:25:23 --> 00:25:25 get less as you get farther away from the
00:25:25 --> 00:25:27 sun. And that's part of the equation with a
00:25:27 --> 00:25:29 slingsot, because what you're trying to do is
00:25:29 --> 00:25:32 steal some momentum from the planet and, and
00:25:32 --> 00:25:34 give it to the spacecraft. And so there are
00:25:34 --> 00:25:37 upper limits, uh, on, um, what sort of
00:25:37 --> 00:25:40 velocity change you can get. It depends on
00:25:40 --> 00:25:41 how close you go to the planet, depends
00:25:41 --> 00:25:43 whether the planet's got an atmosphere or
00:25:43 --> 00:25:45 not. It, uh, depends on the angle that you
00:25:45 --> 00:25:47 come in. Um, the figure that I've seen
00:25:47 --> 00:25:50 quoted As a maximum for Jupiter, which is
00:25:50 --> 00:25:52 the most effective planet for this sort of
00:25:52 --> 00:25:54 thing, being by far the most massive planet
00:25:54 --> 00:25:56 in the solar system, is a change of 40
00:25:56 --> 00:25:59 kilometres per second. Um, now
00:25:59 --> 00:26:02 that's very good if you're you know, trying
00:26:02 --> 00:26:04 to get something out to the outer solar
00:26:04 --> 00:26:06 system, but it's not going to help you
00:26:06 --> 00:26:09 getting things to other planets.
00:26:09 --> 00:26:11 Especially when you think, you know, if you
00:26:11 --> 00:26:14 give uh, a planet, sorry
00:26:14 --> 00:26:16 a spacecraft, an impulse
00:26:17 --> 00:26:19 Delta V of 40 kilometres per second by
00:26:19 --> 00:26:22 interacting with Jupiter, you've got to then
00:26:23 --> 00:26:25 find another planet that's, that's going to
00:26:25 --> 00:26:28 give it even more. But the other planets are
00:26:28 --> 00:26:31 all moving slower than that so uh,
00:26:31 --> 00:26:33 the change in momentum is a lot harder to
00:26:33 --> 00:26:36 get. Uh, so I think the answer is it's a
00:26:36 --> 00:26:39 very nice idea. As Joe suggests, winding up
00:26:39 --> 00:26:41 by all these gravitational interactions, you
00:26:41 --> 00:26:44 can only do it within limits. You're not
00:26:44 --> 00:26:46 going to be able to get like 100
00:26:46 --> 00:26:48 kilometres per second or something like that
00:26:48 --> 00:26:49 from doing that.
00:26:49 --> 00:26:52 Andrew Dunkley: Yeah, I suppose you could equate it to using
00:26:52 --> 00:26:55 a slingshot or a shanghai. There's only so
00:26:55 --> 00:26:57 much tension you can push, put in, into the,
00:26:57 --> 00:26:59 the rubber band, let's say to fire the rock.
00:26:59 --> 00:27:01 And you're not going to be able to fire the
00:27:01 --> 00:27:04 rock any faster than the maximum
00:27:04 --> 00:27:06 amount of storage the rubber band can hold.
00:27:06 --> 00:27:08 And I'm guessing it's the same.
00:27:09 --> 00:27:11 Professor Fred Watson: Yes, there's a, there's a limited amount of
00:27:11 --> 00:27:13 energy that you can get from, from a
00:27:13 --> 00:27:16 slingshot. That's right, yeah. Nice
00:27:16 --> 00:27:17 idea there.
00:27:17 --> 00:27:19 Andrew Dunkley: Although it's, it's been very effective as
00:27:19 --> 00:27:22 you said, for sending things to the outer
00:27:22 --> 00:27:24 solar system. The, the Voyager probes
00:27:24 --> 00:27:27 particularly uh, used um,
00:27:27 --> 00:27:30 the slingshot effect, um, several
00:27:30 --> 00:27:33 times to get to the outer solar system
00:27:33 --> 00:27:35 because they didn't have the fuel to do it.
00:27:36 --> 00:27:38 So they figured out through um,
00:27:39 --> 00:27:42 an alignment of the planets that they
00:27:42 --> 00:27:44 could get out there just by using
00:27:45 --> 00:27:48 the rotation of the planets or um,
00:27:48 --> 00:27:51 the process uh, that uh, uh,
00:27:51 --> 00:27:54 Joe's been talking about. So um, yeah it does
00:27:54 --> 00:27:57 work quite effectively for slower,
00:27:58 --> 00:28:00 slower speeds that uh, yeah,
00:28:00 --> 00:28:03 interstellar, probably beyond us in that
00:28:03 --> 00:28:04 regard.
00:28:04 --> 00:28:07 Professor Fred Watson: Yeah, probably the lasers and um,
00:28:07 --> 00:28:09 you know in a solar cell or a light sail
00:28:09 --> 00:28:12 might be a better bet. But even that beyond
00:28:12 --> 00:28:13 our technology at the moment.
00:28:16 --> 00:28:18 Andrew Dunkley: Um, probably won't be for long though. I
00:28:18 --> 00:28:20 think they'll develop that and get some
00:28:20 --> 00:28:23 spacecraft heading out towards the Alpha
00:28:23 --> 00:28:25 Centauri sector and um,
00:28:25 --> 00:28:28 anyway that remains to be seen. Uh, but that
00:28:28 --> 00:28:30 would still be a pretty slow mission in the
00:28:30 --> 00:28:32 scheme of things. But um, yeah, great
00:28:32 --> 00:28:34 question Joe, thanks for sending it in. And
00:28:34 --> 00:28:37 if you'd like to send us a question, uh,
00:28:37 --> 00:28:40 you can do that, uh, through our website,
00:28:40 --> 00:28:42 spacenutspodcast.com spacenuts
00:28:42 --> 00:28:45 IO. Click on the AMA link at the top
00:28:45 --> 00:28:48 and you can send us text and audio questions.
00:28:48 --> 00:28:50 And don't forget to tell us who you are and
00:28:50 --> 00:28:52 where you're from. We love to know that sort
00:28:52 --> 00:28:54 of stuff so that we can send the boys around.
00:28:54 --> 00:28:56 Or, uh, we could send Huw around because he
00:28:56 --> 00:28:58 can't be with us today, so he must be
00:28:58 --> 00:29:01 visiting one of you guys, um, with his, with
00:29:01 --> 00:29:03 his, um, you know, balaclava on,
00:29:03 --> 00:29:04 maybe. Yeah.
00:29:05 --> 00:29:06 Professor Fred Watson: Thank, um, you, Fred Watson, as always, a
00:29:06 --> 00:29:09 pleasure. Andrew, as always. Good to talk and
00:29:09 --> 00:29:11 uh, good to hear our listeners questions.
00:29:11 --> 00:29:12 It's.
00:29:12 --> 00:29:15 Andrew Dunkley: It is, it is. All right, well catch you again
00:29:15 --> 00:29:17 real soon. Professor Fred Watson Watson,
00:29:17 --> 00:29:19 astronomer at large, and from me, Andrew
00:29:19 --> 00:29:21 Dunkley. Thanks for your company. See you on
00:29:21 --> 00:29:23 the next episode of Space Nuts. Bye for now.
00:29:24 --> 00:29:26 Professor Fred Watson: You've been listening to the Space Nuts.
00:29:26 --> 00:29:29 Andrew Dunkley: Podcast, available at
00:29:29 --> 00:29:31 Apple Podcasts, Spotify,
00:29:32 --> 00:29:34 iHeartRadio or your favourite podcast
00:29:34 --> 00:29:36 player. You can also stream on
00:29:36 --> 00:29:39 demand@bytes.com. um, this has been another
00:29:39 --> 00:29:41 quality podcast production from Bytes.
00:29:42 --> 00:29:42 Professor Fred Watson: Com.