Latest / Space Nuts: Astronomy Insights & Cosmic Discoveries / Cosmic Queries: Space Emptiness, Tidally Locked Worlds & Sonic Orbits

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Cosmic Queries: Space Emptiness, Tidally Locked Worlds & Sonic Orbits · Space Nuts: Astronomy Insights & Cosmic Discoveries

• 0:00
  Andrew Dunkley: Hello again. Thanks for joining us on Space
• 0:01
  Nuts. My name is Andrew Dunkley, your host,
• 0:04
  and this is a Q and A edition. And questions
• 0:07
  today coming from Kevin about, uh,
• 0:10
  the emptiness of space. Uh, Casey
• 0:13
  wants to talk about tidally locked planets.
• 0:16
  Hazel is asking about sonification.
• 0:18
  We've talked about that in the past. And
• 0:21
  Rusty. Uh, Rusty. Gee,
• 0:23
  it's good to be back. Uh, I really missed
• 0:26
  you, Rusty. And your questions about bulk
• 0:28
  motions in the Universe can't wait.
• 0:31
  Voice Over Guy: 15 seconds. Guidance is internal.
• 0:33
  10, 9. Ignition
• 0:36
  sequence start. Space nuts. 5, 4, 3,
• 0:39
  2. 1, 2, 3, 4, 5, 5, 4,
• 0:42
  3, 2, 1. Space nuts. Astronauts
• 0:45
  report it feels good.
• 0:47
  Andrew Dunkley: Joining us once again is his good self,
• 0:49
  Professor Fred Watson. What's that?
• 0:50
  Astronomer at large. Hello, Fred Watson.
• 0:53
  Professor Fred Watson: Hello, Andrew. Good to be back. And good to
• 0:55
  see your smiling face again.
• 0:57
  Andrew Dunkley: Yes, I've got a smiling face. I'm nearly over
• 0:59
  the jet lag. You don't smile much when you
• 1:01
  got jet lag. That stuff's horrible.
• 1:04
  Professor Fred Watson: Yeah.
• 1:05
  Andrew Dunkley: Um, there should be a pill for that. There
• 1:07
  really should. Don't know why someone hasn't
• 1:10
  invented one yet. Maybe I should. I'd make
• 1:12
  billions, I would.
• 1:14
  Professor Fred Watson: Here, take this.
• 1:15
  Andrew Dunkley: No jet lag. Done and dusted. How you been,
• 1:18
  Fred Watson?
• 1:19
  Professor Fred Watson: Uh, very well, thanks. I don't have jet lag.
• 1:21
  Um, and that's good. Um, I guess the
• 1:24
  nearest to a jet lag pill is melatonin. Um,
• 1:27
  some of my colleagues who travel a lot used
• 1:29
  to insist on melatonin tablets.
• 1:32
  I've never used them because I always managed
• 1:35
  to sleep. All right. But you're right, jet
• 1:36
  lag can be a bit fearsome.
• 1:39
  Andrew Dunkley: Yeah. And you don't want to get the melatonin
• 1:41
  tablets mixed up with the melanoma tablets,
• 1:43
  because that can be lethal.
• 1:45
  Professor Fred Watson: That's right. That could be, uh.
• 1:47
  Andrew Dunkley: That's a terrible joke. See, I'm back. I'm
• 1:49
  back. Dreadful jokes.
• 1:53
  Um, we might as well get straight into it and
• 1:55
  see if we can solve some of these riddles
• 1:57
  that people have sent to us. Our first
• 2:00
  question comes from Kevin. Uh, Kevin is a
• 2:03
  patron and gives, uh, me an opportunity to
• 2:05
  thank all our patrons for pitching, uh, into
• 2:07
  the show. We really do appreciate that, and
• 2:10
  we think you are terrific. And if
• 2:13
  anyone wants to, uh, look into that, they can
• 2:16
  do that via our website, um, Patreon,
• 2:18
  uh,.comspacenuts, I think, is also where you
• 2:20
  can go.
• 2:21
  So Kevin's question. How
• 2:24
  empty is space? Or to ask
• 2:27
  another way, how is a
• 2:29
  spacecraft like New Horizons?
• 2:32
  Professor Fred Watson: Ah.
• 2:32
  Andrew Dunkley: How is it that it can travel millions of
• 2:34
  miles through space and risk, um,
• 2:37
  hitting a Grain of matter that I assume would
• 2:39
  destroy it. Um, and that's
• 2:42
  a really good question because I've often
• 2:44
  wondered the same thing. How do we go through
• 2:47
  space, uh, and not get
• 2:50
  hammered by something and. Yeah,
• 2:52
  oblivion.
• 2:54
  Professor Fred Watson: Um, yeah, it is a great question. Uh, it's
• 2:57
  got um, a uh, very
• 3:00
  characteristic two word, uh answer, Andrew,
• 3:02
  which is. That's a wonder. No,
• 3:06
  no, b. Of course, yeah, you're right.
• 3:10
  Uh, how empty is space? It
• 3:13
  depends. Uh, and it depends, it
• 3:16
  depends which bit of space you're in. Um, and
• 3:19
  so, uh, yeah, I think Kevin's right.
• 3:24
  Um, thinking about the James Webb Space
• 3:26
  Telescope which indeed did travel,
• 3:28
  uh, well, it's 1.5 million kilometres.
• 3:31
  So it's about a million miles. That was the
• 3:33
  distance that it travelled from Earth uh, to
• 3:36
  its uh, location,
• 3:39
  uh, because it settled in a uh, region
• 3:42
  called the Lagrange second Lagrange point
• 3:44
  L2 where the stable gravitational
• 3:47
  pull. But uh, one of the
• 3:50
  other things about the Lagrange points is
• 3:52
  because they're stable they attract dust.
• 3:55
  Um, and so they're relatively dusty regions
• 3:58
  of space. Um, and actually within just
• 4:01
  a few months of um, uh,
• 4:04
  of the deployment of the jwst,
• 4:07
  there was a micrometeorite, um,
• 4:10
  impact. This would be something the size of
• 4:13
  grain of dust, maybe even smaller, hitting at
• 4:16
  maybe 30 kilometres per second. That left a
• 4:18
  permanent dent in one of the mirror segments
• 4:22
  today. Yes, um, they've been
• 4:24
  quite lucky actually because I thought, you
• 4:26
  know, that was within a couple of months of
• 4:28
  deployment. I was thinking my God, if that's
• 4:31
  the case, we're going to have no mirror at
• 4:32
  all within a year. But in fact I think
• 4:35
  it's been relatively unscathed uh,
• 4:38
  uh, for the rest of its career. It's doing a
• 4:40
  fabulous job. We often talk about oh isn't
• 4:43
  JWST observations uh, here
• 4:46
  on spacenuts. So um,
• 4:49
  basically what I'm saying is that the Earth's
• 4:51
  environment in particular is quite dusty and
• 4:53
  that's because it's near the inner part of
• 4:55
  the solar system. There's a lot of comets
• 4:57
  come from the outer edges of the solar system
• 5:00
  which shed dust as they get near the sun. The
• 5:03
  dust is released from its IC matrix and
• 5:06
  uh, and so comet trails are dusty, uh,
• 5:08
  and that uh, adds to the uh,
• 5:11
  general dust that is the remnant of the
• 5:14
  origins of the solar system. The plane of the
• 5:17
  Earth's orbit is quite dusty. And so yes,
• 5:19
  something like the web is going to be always
• 5:22
  at risk uh, from uh,
• 5:25
  being hit by rain of material. But if you go
• 5:27
  out um, into the outer part
• 5:30
  of the solar system, uh, beyond the orbit of
• 5:33
  Neptune. You get a much clearer view because
• 5:35
  there's virtually no dust out there. Uh, and
• 5:38
  that's one reason why the New Horizons
• 5:41
  spacecraft measured, uh, the
• 5:43
  sky background there as being fainter
• 5:46
  than we have in the inner solar system,
• 5:48
  because there's no dust reflecting
• 5:50
  sunlight. Um, and that's an interesting
• 5:53
  experiment. It actually caused a bit of a
• 5:54
  revision of the number of galaxies that we
• 5:57
  think the universe has. Um, I'm not
• 5:59
  going to go in that direction now because
• 6:01
  it's another can of worms. But, uh, what
• 6:03
  that's saying is that, uh, in terms of dust,
• 6:06
  uh, once you get beyond the inner solar
• 6:08
  system, then it's fairly dust free.
• 6:11
  Of course, there's other stuff, uh, floating
• 6:13
  around in space. Lots of subatomic
• 6:16
  particles. There's the wind of subatomic
• 6:18
  particles that come from the sun. They can
• 6:20
  have an effect, not putting a dent in your
• 6:23
  mirror, but certainly can damage, uh,
• 6:25
  electronics and things of that sort at the
• 6:27
  atomic level. Uh, and once again,
• 6:30
  that's, um, more true nearer to the sun than
• 6:33
  further out. So when you get to interstellar
• 6:35
  space, uh, the average density is pretty low,
• 6:38
  Although interstellar space is populated by
• 6:40
  giant clouds of gas and dust. Uh, and so if
• 6:43
  you get in one of those, suddenly you've got,
• 6:45
  um, material around you again. It's still
• 6:48
  very, very rarefied. It's still better than
• 6:50
  the highest vacuum we can create artificially
• 6:52
  on Earth. But, um, it's not empty
• 6:55
  completely. Uh, one of the things, though,
• 6:58
  that illuminates to me just how empty space
• 7:00
  is, is the fact that we can look
• 7:03
  through space, uh, to a time,
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  uh, 13.8 billion years ago,
• 7:10
  uh, when the universe was still glowing
• 7:12
  brightly. We can still see the flash of the
• 7:13
  Big Bang. And that's because the photons that
• 7:16
  were emitted 13.8 billion years
• 7:19
  ago are still going strong. Uh, we see
• 7:21
  them now as microwaves, uh, because the
• 7:24
  universe, the expansion of the universe, has
• 7:26
  stretched them their waveleng. Uh, but that
• 7:29
  tells you how empty space is. The fact that
• 7:30
  we can see distant galaxies out to almost the
• 7:33
  origin of galaxies, and then beyond that,
• 7:36
  we can see the cosmic microwave background
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  radiation. Uh, you'd think there will be
• 7:41
  something in the universe that will make it a
• 7:43
  bit more opaque than it is, but it is
• 7:45
  incredibly transparent, which tells you that
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  it's pretty damned empty.
• 7:49
  Andrew Dunkley: You were also like, I haven't. It's been
• 7:52
  three months and I haven't been able to
• 7:53
  insult Huw once. So, um, you know, what you
• 7:56
  just said also applies to Huw Um,
• 7:59
  you know, empty, big void, nothing.
• 8:04
  Professor Fred Watson: Don't know why you're. No reaction.
• 8:06
  Andrew Dunkley: No reaction from you.
• 8:09
  So diplomatic. Sorry, Huw, couldn't
• 8:12
  help it. Golden opportunity. But
• 8:15
  yeah, in answer to Kevin's question, though,
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  it's pretty sparse. Like, you know, you'd
• 8:19
  have to be very unlucky to take your 30
• 8:22
  gazillion dollar Ferrari
• 8:24
  spaceship out there and suddenly realise
• 8:27
  that it's been destroyed by a spec dust.
• 8:30
  You have to be, you know,
• 8:34
  really unlucky. Well, hang on, maybe
• 8:37
  a Tesla Roadster.
• 8:38
  Professor Fred Watson: Yeah.
• 8:39
  Andrew Dunkley: Or something like that. You never know.
• 8:42
  Professor Fred Watson: That's right.
• 8:42
  Andrew Dunkley: Um, thank you Kevin, and thank you for your
• 8:44
  ongoing support as a patron of space
• 8:47
  nuts. We appreciate it. Our, uh, next
• 8:50
  question, Fred Watson, comes from
• 8:52
  Casey, who sent us an audio
• 8:55
  question.
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  Professor Fred Watson: Hi guys, this is Casey from Colorado again.
• 8:59
  And today I have a question about tidally
• 9:01
  locked planets. I know that a tidally locked
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  planet is a planet that always has the same
• 9:06
  side facing its star and that this happens
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  because the orbital and rotational
• 9:11
  periods are the same. What I'm wondering
• 9:14
  about is how this might affect the formation
• 9:16
  of compounds and molecules. I hope you're
• 9:19
  both well and thank you for taking the time
• 9:21
  to answer so many of my questions.
• 9:23
  Andrew Dunkley: Thank you, Casey. It's lovely to hear from
• 9:25
  the ladies. I know there was a big push on to
• 9:27
  get more, uh, female listeners. Listeners to,
• 9:29
  um, send in questions. Uh, and that seems
• 9:32
  to have been very successful. So well done,
• 9:34
  Heidi. Uh, yeah. So what
• 9:37
  is the answer to Casey's query?
• 9:39
  Professor Fred Watson: Um, I think it's a great question actually.
• 9:42
  These, yeah, the, um, you know, if you've got
• 9:45
  a planet always has one side facing
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  its parent star, that side is going to be
• 9:51
  pretty hot. But the other side is facing
• 9:54
  the depths of space. It's facing the cold of
• 9:57
  space and it could be pretty cold. You know,
• 9:59
  you could be way below zero, perhaps
• 10:02
  200 degrees below zero on one side and
• 10:05
  perhaps 100 or 200 degrees above zero on the
• 10:07
  other. Um, so, um,
• 10:10
  molecules, for molecules and compounds to
• 10:13
  form, uh, they're like sort of
• 10:16
  moderate temperatures. Temperatures measured
• 10:19
  in tens, hundreds, maybe thousands of
• 10:21
  degrees. Knots tens of thousands of degrees.
• 10:25
  So, um, you might find that compounds are not
• 10:27
  going to form, uh, on the
• 10:30
  sun facing, on the star facing side of the
• 10:32
  planet because it's too hot. Compounds,
• 10:35
  uh, just get shredded apart
• 10:38
  into their component atoms by the energy of
• 10:40
  the heat. On the other side, it's too cold.
• 10:43
  Uh, so your, your molecules never
• 10:46
  kind of get together. There's not enough
• 10:47
  motion of the gases in an
• 10:50
  atmosphere for the molecules to come together
• 10:52
  and react but, but, uh, in between the
• 10:55
  two is this region that we always call the
• 10:57
  terminator. That's the region between the
• 10:59
  light side of a planet or the boundary
• 11:02
  between the light side of a planet and its
• 11:03
  dark side. And it could well be because the
• 11:06
  planet's not rotating. You might find that
• 11:08
  there the temperatures, ah, are sort of, you
• 11:11
  know, temperate, uh, all the time, um,
• 11:14
  promoting the formation of molecules and
• 11:16
  compounds. So for a tidally locked
• 11:19
  planet, it is possible that you could have
• 11:22
  this zone around the terminator which is
• 11:24
  quite rich in chemical reactions, action. So,
• 11:26
  um, yeah, Casey, I think you're onto
• 11:28
  something there. Maybe there will be this
• 11:30
  zone that might be habitable even in what
• 11:33
  looks like an otherwise uninhabitable world,
• 11:35
  because one side's too hot and the other
• 11:36
  side's too cold. Ah, you might find there's a
• 11:39
  zone that's not so. Yeah, good question.
• 11:41
  Andrew Dunkley: Excellent question. Thank you, Casey. And
• 11:43
  keep them coming. And, um, yeah, good to hear
• 11:46
  from you. And, uh, you know, when it comes
• 11:48
  to, um, dealing with, uh,
• 11:51
  extreme cold, uh, I'm sure you handle it well
• 11:53
  in Colorado. I don't know how you do it.
• 11:57
  Okay, okay. Um. Like, we were in Iceland
• 12:00
  in summer, and I think the maximum
• 12:02
  temperature was 6 degrees. Uh, and I
• 12:05
  thought, if that's summer, I would hate to be
• 12:07
  here in winter. That was, uh, quite strange.
• 12:09
  But then. Not sure if I told you,
• 12:12
  Fred Watson, but we. When we were at North
• 12:13
  Cape in Norway, the northernmost tip of
• 12:16
  Europe, it was 28 degrees
• 12:19
  that day. And I looked up the weather
• 12:21
  records for North Cape, and the highest
• 12:23
  they'd ever recorded there was 28.4 war. So
• 12:26
  we'd nearly hit it the day we were there.
• 12:30
  And the locals were freaking out, like they
• 12:33
  thought it was horrible. It's walking around,
• 12:35
  making. It was so hot. But, um, we just
• 12:38
  went, oh, isn't this lovely?
• 12:41
  Professor Fred Watson: So when we were there in, um. When we were
• 12:43
  there in January, uh,
• 12:46
  there was snow everywhere, but it was still
• 12:48
  unseasonably warm. Uh, it was
• 12:50
  some. It was probably more like 6 degrees,
• 12:52
  the 6 that you had in Iceland. Um, we
• 12:55
  tend to go to all these countries in the
• 12:57
  depths of winter so that we get the most
• 12:59
  darkness and we see the aurora. So you'll
• 13:01
  definitely have to come with us sometime,
• 13:03
  Andrew, uh, because we always see it.
• 13:06
  Uh, and, um, um. Uh, that's why
• 13:08
  we're at North Cape. You know, when there was
• 13:11
  a matter of perhaps two or three hours of
• 13:13
  daylight. It was great, though, up there. And
• 13:15
  you would have stood by that huge
• 13:17
  analemosphere. That's right. At the tip of
• 13:20
  the North, North Cape. Um, we saw that
• 13:22
  in twilight. Uh, but yes, it was
• 13:25
  still unseasonably warm. It was snow. There
• 13:27
  was snow everywhere. Uh, but it was um,
• 13:29
  certainly above zero.
• 13:31
  Andrew Dunkley: Yeah, it's an incredible place. It's
• 13:33
  certainly um, you know one of those like we,
• 13:35
  we went around the southern tip of Africa
• 13:37
  which is right, um, the Cape of Good Hope
• 13:39
  right down south. And then you know,
• 13:42
  a month later we're standing on the northern
• 13:44
  tip of Europe. Yeah, caught it. Quite an
• 13:46
  incredible trip. Thanks Casey. Great to hear
• 13:48
  from you. This is Space Nuts with Andrew
• 13:50
  Dunkley and Professor Fred Watson Watson.
• 13:55
  Three, two, one.
• 13:58
  Space Nuts. And you're listening to a Q and
• 14:01
  A edition. And our next question comes from
• 14:04
  Hazel.
• 14:05
  Uh, and Hazel uh, says hi. I think we've all
• 14:08
  heard the musical adaption of orbits in the
• 14:11
  solar system sonification and how it
• 14:13
  highlights the beautiful resonance. And she
• 14:15
  says I love this. Uh, my question is to
• 14:18
  do with uh, most orbiting things.
• 14:21
  Uh, do most orbiting things experience
• 14:24
  this? Would galaxies orbiting their
• 14:27
  centre of mass also experience this? I feel
• 14:30
  Kepler in his genius got the um,
• 14:33
  uh, got to the bottom of this. But I find it
• 14:35
  fascinating. Love the show. Much love to you
• 14:37
  all. Hazel from Scotland. Scotland.
• 14:40
  What a lovely place that is. Rained all the
• 14:42
  time. Uh, but anyway, um,
• 14:46
  while we were there anyway I uh, remember
• 14:48
  us um, actually playing some of that
• 14:51
  sonification production where they took a
• 14:53
  photo, uh, wide angle photo
• 14:57
  or, or image of a portion of the universe
• 15:00
  and they applied sounds to this,
• 15:03
  the different objects and created this
• 15:05
  beautiful music. So would that apply
• 15:08
  elsewhere, uh, in other parts of the
• 15:11
  universe?
• 15:12
  Professor Fred Watson: Uh, so yes. So the tonifications that Hazel's
• 15:15
  talking about are a little bit different from
• 15:16
  that. And um, you know, I.
• 15:18
  Andrew Dunkley: Is this something I missed while I was away?
• 15:21
  Professor Fred Watson: Um, no you didn't. Oh,
• 15:23
  okay. Um, um, um.
• 15:26
  When, when I read Hazel's question I went to
• 15:29
  that. Exactly the picture that you're talking
• 15:31
  about. There's one that I particularly like.
• 15:33
  It's the galactic centre and all the
• 15:34
  stardust. Yeah, that's LinkedIn the less
• 15:36
  beautiful. And uh, it's still, it's pretty
• 15:38
  easy to find. It's on NASA's website. But
• 15:40
  what Hazel's talking about is
• 15:43
  the resonances between
• 15:46
  the planets. Uh, for example in
• 15:49
  a solar system. So that you've got a
• 15:52
  situation where one planet goes around once.
• 15:56
  Uh, uh, the one next to it
• 15:58
  on the inside goes around twice in the same
• 16:01
  time. The one on the outside of it goes
• 16:03
  around a half in the same time. So there's
• 16:05
  this uh. What we call orbital resonances.
• 16:09
  And you can sonify. Yeah, you can
• 16:11
  sonificate that. Uh, and in a sense it's
• 16:14
  what um, Kepler was doing when he wrote
• 16:16
  Harmonium Mundi, the Harmony of the Spheres
• 16:19
  or the harmony of the Worlds. Uh, he was
• 16:22
  looking at all these different
• 16:24
  resonances. Um, and the most obvious in our
• 16:27
  solar system is with some of
• 16:30
  the moons of Jupiter. Ganymede, Europa and IO
• 16:33
  are in a 4, 2 and 1 resonance with EO.
• 16:36
  Ganymede, um, 4 to 1, Europa, 2 to 1,
• 16:39
  EO, 1 to 1. So um, that's
• 16:42
  basically uh, the sort of thing that
• 16:45
  ah, Kepler was looking at because he said,
• 16:47
  well this is very similar to the. You know,
• 16:50
  the intervals on a musical scale where you've
• 16:52
  got fourths and fifths and these make chords
• 16:54
  that are pleasant to our ears. And so his
• 16:56
  harmony of the worlds was based on all that.
• 16:59
  But now we've got so many more examples
• 17:02
  with these extra, um, extrasolar
• 17:05
  planets. Uh, and there are some of them that
• 17:08
  have got really quite spectacular resonances.
• 17:11
  And I might refer, Hazel, to a very
• 17:14
  nice article that uh, appeared on the
• 17:17
  Conversation a year last February. It's
• 17:19
  written by a good friend of mine, Chris
• 17:20
  Impey. He and I were research students
• 17:22
  together actually in Edinburgh at the um,
• 17:25
  University of Edinburgh. Chris, uh, has been
• 17:27
  the. Chris has
• 17:30
  been. Ah, I'm glad you went there. It's good
• 17:32
  that you especially had haggis. I think that
• 17:34
  was very good for you. Uh, Lewis
• 17:37
  as basically most of his career as I've
• 17:39
  worked in Australia, he's worked in the
• 17:41
  United States principally at the University
• 17:43
  of Arizona where he's a distinguished
• 17:45
  professor of astronomy. Um, but he's written
• 17:48
  a lovely article on exactly this. Uh,
• 17:51
  it is called orbital resonance. The striking
• 17:53
  gravitational dance done by planets with
• 17:56
  aligning orbits. And it's worth looking at
• 17:59
  because Hazel, because it's got um, a
• 18:01
  list of uh, several of
• 18:04
  the major resonances around uh,
• 18:07
  uh, planets going around other stars like
• 18:10
  Gliese 876 which has got some 4 to
• 18:13
  2 to 1 orbital ratios. Kepler
• 18:16
  2:3, 3:4 planets with ratios of 8 to 6
• 18:19
  to 4 to 3. Uh, and there's a number
• 18:21
  of them. Uh, Trappist 1 is the record holder.
• 18:24
  It's got seven Earth like planets, um, with
• 18:27
  orbit ratios you don't need to know. It's uh.
• 18:29
  Well, it's 24 to 15 to 9 to 6 to 4 to 3 to
• 18:32
  2. So those are all what we call
• 18:35
  resonances. And you can turn them uh, into
• 18:37
  music. Uh, and uh, you can have orbital
• 18:40
  Sonification. And so Chris's article has got
• 18:43
  some nice links to the sonification of these
• 18:46
  orbits. There's a very nice one that, uh,
• 18:48
  eso, the European Southern Observatory, has
• 18:50
  done on one of the systems that, um,
• 18:53
  they've found. I think it's, um. Can't
• 18:55
  remember which system it is. I think it's
• 18:57
  tri178. Uh, you'll find a
• 19:00
  lovely audio of that. Um. Uh. If
• 19:03
  we'd been better organised, Andrew, we might
• 19:04
  have dug one of these out and, uh, played it
• 19:06
  for the show. Uh, but anyway, that's the
• 19:09
  place to look. It's a great article. It
• 19:10
  explains it very clearly.
• 19:12
  Your question about, um. Uh. Uh,
• 19:15
  resonances in galactic orbits is very
• 19:17
  much less easy to answer.
• 19:20
  Uh, we suspect not because,
• 19:23
  um, the number of stars in orbit around the
• 19:26
  galactic centre, 3 or 400 billion, means
• 19:29
  it's more like a cloud of particles, um, that
• 19:31
  behave in a different way from what
• 19:33
  individual objects do. It's more like a cloud
• 19:35
  of stuff going around the centre of the
• 19:37
  galaxy rather than specific planets with
• 19:39
  their own centre of mass and their own
• 19:41
  resonances. So I don't think there are,
• 19:44
  uh, resonances to be found in galactic
• 19:46
  orbits. I'm happy to be proved wrong, though.
• 19:50
  Yeah.
• 19:51
  Andrew Dunkley: Never say never for any.
• 19:52
  Professor Fred Watson: I think it's never say never. That's right,
• 19:54
  yeah.
• 19:55
  Andrew Dunkley: Yeah. Wonderful. Uh, Hazel, thank
• 19:58
  you. And, um.
• 19:59
  Professor Fred Watson: Um.
• 20:00
  Andrew Dunkley: I. I must say I loved Scotland while I was
• 20:02
  there. It was a brief visit but, um, I'm glad
• 20:05
  I got to see it and. And travel, uh, from
• 20:08
  Glasgow across to Edinburgh and back.
• 20:11
  Um. Yeah, lovely part of the world. Even that
• 20:14
  was cold and wet and. Yeah, well, it wasn't
• 20:16
  windy. That's the only. Wasn't too windy, but
• 20:19
  the rest of it was. It was supposed to be
• 20:21
  summer, Fred Watson. I don't. You know, I
• 20:24
  don't know how people live in the northern.
• 20:25
  Now most of the world population lives in the
• 20:27
  northern hemisphere and from my experience,
• 20:29
  the weather's so much worse up there.
• 20:33
  Professor Fred Watson: If you, um. Yes, that's right. If you, um,
• 20:35
  drove on the M9, as you probably did, if you
• 20:37
  went by car from, uh, Glasgow to Edinburgh,
• 20:40
  you would have passed the Kelpies. Uh. Would
• 20:43
  you have passed the Kelpies? Yes, you would.
• 20:44
  I think they're on that road.
• 20:47
  Two huge statues of Celtic water horses.
• 20:50
  You might have seen them.
• 20:51
  Andrew Dunkley: Yeah. There's also sculptures along there,
• 20:54
  like a whole bunch of different things.
• 20:57
  Professor Fred Watson: Yes.
• 20:57
  Andrew Dunkley: Yeah, we did spot a few along the way.
• 20:59
  Professor Fred Watson: Yes.
• 21:00
  Andrew Dunkley: It's quite weird ones. They got a great
• 21:02
  sculpture in Glasgow of, um. 2 is it.
• 21:05
  Professor Fred Watson: Ship builders. I think they were ship
• 21:06
  builders.
• 21:08
  Andrew Dunkley: Um, humongous things with giant
• 21:10
  sledgehammers. Yeah, it was. That's. That was
• 21:13
  a beautiful statue as well. M. Uh, thanks,
• 21:15
  Hazel. Great to hear from you.
• 21:20
  Three, two, one.
• 21:22
  Space nuts.
• 21:24
  Our final question. Oh, good grief. Here we
• 21:27
  go. Comes from
• 21:29
  Rusty.
• 21:30
  Rusty: Hey, Fred Watson. And Andrew. And maybe
• 21:32
  Heidi. It's Rusty and Donnybrook.
• 21:36
  I'll try and keep it simple as I always do.
• 21:38
  The peculiar motion of the Local Group
• 21:40
  towards the Virgo Cluster and onwards to the
• 21:42
  Great Attractor. Uh, in the Hydro Centaurus
• 21:45
  supercluster. Turns out to be the same as
• 21:48
  the overall supercluster itself. When
• 21:50
  observed in a co moving reference frame
• 21:53
  where the observer is at rest relative
• 21:56
  to the cmb.
• 21:59
  Now the, uh, Lambda CDM M
• 22:03
  is invoked to explain this enormous peculiar
• 22:05
  flow. Space
• 22:08
  was already effectively infinite when matter
• 22:10
  first appeared. 380,000 years after the Big
• 22:13
  Bang. If we look at explosions in the
• 22:16
  vacuum of space, for example a Crab Nebula,
• 22:19
  we find filaments and voids.
• 22:22
  But in the everywhere all at once explosive
• 22:24
  birth of matter. In the highly energetic
• 22:27
  universe, resulting flows could have
• 22:29
  happened in any direction. Could
• 22:32
  this be what we are seeing? See, that's
• 22:35
  a simple question. Thanks, people.
• 22:38
  Cheers.
• 22:40
  Andrew Dunkley: Yeah, okay. Right.
• 22:42
  I see. Uh, thank you, Rusty. Uh,
• 22:46
  so good to hear from you. Um, my
• 22:49
  brain hurts, Fred Watson. I'm very confused.
• 22:52
  Professor Fred Watson: Uh, um, I was going to let you answer this
• 22:54
  one, Andrew. I thought you can talk to us.
• 22:57
  Andrew Dunkley: I've got an answer for him because.
• 23:00
  Professor Fred Watson: Yeah, um, there's a few.
• 23:03
  There's a lot in there that I'm not gonna
• 23:05
  unpick. Thank you, Rusty. Um, matter
• 23:08
  actually appeared in the first three minutes,
• 23:09
  not the first 380, 000 years. Uh,
• 23:13
  when, um, uh, the radiation got cool
• 23:16
  enough for atoms to form. Uh,
• 23:19
  yeah, so, so it didn't take very long. Um,
• 23:22
  and you're absolutely right to,
• 23:25
  uh, quote the filaments because that's what
• 23:28
  happened. Uh, we think that.
• 23:32
  And notwithstanding the peculiar motion of
• 23:34
  galaxies, um, which is basically just
• 23:37
  the, the gravitational pull of
• 23:40
  these filaments of, of dark matter
• 23:43
  probably that's uh, moving them around
• 23:45
  relative to the expansion of the universe.
• 23:47
  Relative to what we call the Hubble flow, um,
• 23:50
  those filaments seem to have been created
• 23:52
  very early, uh, in the expansion of the
• 23:54
  universe. Maybe during the period of
• 23:56
  inflation, which is the first gazillionth of
• 23:58
  a second. Forget three minutes. It's 10 to
• 24:01
  the minus 33, I think is the number. Um, so,
• 24:04
  um, I think the way to look at it,
• 24:07
  I remember, um, uh, My
• 24:10
  young, uh, nephew some time ago, uh, playing
• 24:13
  with some stuff that was. It's kind
• 24:16
  of like play doh.
• 24:17
  Andrew Dunkley: I think.
• 24:18
  Professor Fred Watson: Uh, and he sort of squashed this stuff,
• 24:20
  a lump of this stuff down, uh, between the
• 24:23
  table in his hand. And then lifted it his
• 24:25
  hand up. And what you got was spontaneously
• 24:28
  forming filaments linking one blob to the
• 24:31
  other. And uh, it's just. That's
• 24:34
  seems to be uh, a facet of something
• 24:37
  that's expanding. You, uh, will get
• 24:41
  it probably depends on viscosity. And
• 24:43
  well, space time doesn't have any viscosity.
• 24:46
  We discussed that in the last Q A session
• 24:49
  of uh, of uh, space Notes. But
• 24:51
  it's still light. It did form filaments and
• 24:54
  we, we can see them today. We see the
• 24:56
  structure of galaxies on the. On a much wider
• 24:58
  scale than we're talking about the Virgo
• 25:01
  Cluster, which is really nearby. Um, you
• 25:03
  see these, this filamentary, this kind of
• 25:06
  foam like structure of the universe. Which
• 25:08
  seems to just have been an artefact of the
• 25:11
  expansion, uh, caused because of
• 25:13
  slight differences in temperature in the Big
• 25:16
  Bang plasma. Um, and so the
• 25:19
  dark matter seems to form these filaments.
• 25:22
  The clouds of hydrogen collapsed onto them.
• 25:24
  That's where they form the galaxies. And
• 25:26
  that's why we're still seeing these galaxies
• 25:28
  strung out all over the place. Um,
• 25:31
  so it's not, you know, you don't need. Ah.
• 25:34
  You drew the um, example of the Crab Nebula.
• 25:36
  You're quite right. There's filaments
• 25:37
  everywhere with that. And they all seem to
• 25:39
  radiate out from the centre, the source of
• 25:41
  the explosion. But if you've just got an
• 25:43
  expansion, um, you don't need
• 25:46
  a particular direction for these
• 25:48
  filaments to form in. They'll just give you
• 25:50
  this sort of foam of material, um, which is
• 25:53
  what spacetime is like. And so,
• 25:55
  um, Uh, I don't know that that
• 25:58
  necessarily answers Rusty's question, but I
• 26:00
  hope it gives him some food for thought.
• 26:03
  Andrew Dunkley: Yes.
• 26:03
  Professor Fred Watson: Or it'll.
• 26:04
  Andrew Dunkley: Yeah, it'll just make him ask another
• 26:05
  question.
• 26:06
  That's. That's the problem, isn't it?
• 26:09
  Professor Fred Watson: No, it's great. It's great that we get these.
• 26:12
  Oh, just kidding. Yeah. Yeah.
• 26:15
  Andrew Dunkley: Rusty actually sent me some great photos
• 26:16
  while I was away of uh, I think a couple of
• 26:19
  planets that. That uh, he observed. Oh.
• 26:22
  Great night out of Wa.
• 26:25
  So, uh. Yeah, it was good. So thanks for
• 26:27
  that, Rusty. Um, um, but always great
• 26:30
  to hear from you. Your questions are always
• 26:32
  so far out of left field. I don't. Yeah,
• 26:37
  that's too much. For my brain. Uh, but
• 26:40
  thanks Rusty. Good, uh, to hear from you as
• 26:42
  always. And please keep the questions coming
• 26:44
  in, female and male listeners alike. Uh,
• 26:47
  we, we love to hear from, from everybody.
• 26:51
  Uh, so just go uh, to our website and um, and
• 26:54
  send them in to us. Space, uh,
• 26:56
  nuts podcast.com or Space Nuts
• 26:59
  IO is where you can send text and audio
• 27:01
  questions. And while you're online, jump,
• 27:03
  jump around our website and have a look. I
• 27:05
  don't think anyone's been into the shop for
• 27:07
  months. So, um, Huw's just sitting
• 27:10
  in there surfing the Internet and trying to
• 27:12
  um, figure out the problems of the world.
• 27:14
  Professor Fred Watson: So.
• 27:15
  Andrew Dunkley: Well, you know, um, go and sell something
• 27:17
  here, for crying out loud. Uh, but yes, uh,
• 27:19
  that's on our website. Uh, and we're on
• 27:22
  Facebook and Instagram as well. If you're
• 27:24
  into social media, you can follow us there.
• 27:26
  You don't. Yeah, no obligation. You don't
• 27:28
  have to do anything. You don't have to talk
• 27:29
  to anybody. Just look at the picture. Uh,
• 27:32
  that's how I studied at school. Look at the
• 27:34
  pictures. Yes, that's, that's enough.
• 27:37
  Uh, but, uh, yes, um,
• 27:39
  spacenutspodcast.com spacenats IO
• 27:42
  or facebook.com space nuts or the Space
• 27:44
  Nuts podcast group is another,
• 27:47
  um, group that's very much worth
• 27:50
  following because that's where most of our
• 27:52
  listeners talk to each other. If you want to
• 27:54
  join in. Um, that's enough jibber jabber from
• 27:56
  me. Thank you Fred Watson.
• 27:57
  Professor Fred Watson: As always, great stuff, Andrew. I look
• 28:00
  forward to doing it all again next week.
• 28:03
  Andrew Dunkley: Indeed. Uh, Professor Fred Watson Watson,
• 28:05
  astronomer at large, and thanks to Huw in the
• 28:07
  studio, uh, who couldn't be with us today
• 28:10
  because, um, well, he's a bulk motion in the
• 28:13
  universe and they're pretty slow.
• 28:16
  And from me, Andrew Dunkley. Thanks for your
• 28:17
  company. Catch you on the next episode of
• 28:19
  Space Nuts. Bye bye.
• 28:22
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