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Primordial Black Holes, Ancient Galaxies & The Ultimate Lagrange Point: #488 - Q&A Edition · Space Nuts: Astronomy Insights & Cosmic Discoveries

• 0:00
  Speaker 1: Either thanks for joining us on a Q and A
• 0:02
  Speaker 1: edition or even a Q and A edition of Space Nuts.
• 0:06
  Speaker 2: My name is Andrew Duncle, your host. Great to have
• 0:08
  Speaker 2: your company coming up. This time.
• 0:10
  Speaker 1: We are going to be answering questions from our audience
• 0:12
  Speaker 1: about primordial black holes.
• 0:14
  Speaker 2: This is a what if question. We love those.
• 0:17
  Speaker 1: Someone else is asking about old galaxies. We are looking
• 0:21
  Speaker 1: for the ultimate lagrange point and the accelerating universe, which
• 0:26
  Speaker 1: we debunked in the last episode, but we're going to
• 0:29
  Speaker 1: unbunk it on this episode of Space Nuts.
• 0:33
  Speaker 3: Fifteen second the Channel ten nine ignition.
• 0:39
  Speaker 1: Squench Space Nuts Guy or three two.
• 0:46
  Speaker 2: Space notes as an I reported, Neil Good and.
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  Speaker 1: Joining me again is Professor Fred Watson, Astronomer at Large
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  Speaker 1: and Professor John T. Horner, Professor of Astrophysics. Gentlemen, welcome,
• 0:57
  Speaker 1: thanks for joining us.
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  Speaker 4: Pleasure Andrew, good to be here. Good to have Chnty
• 1:02
  Speaker 4: on board as well.
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  Speaker 2: Which this is.
• 1:05
  Speaker 1: Your last show for a little while because you're jetting
• 1:09
  Speaker 1: off to.
• 1:12
  Speaker 4: Well it's Sweden, Norway, Iceland and Greenland and this will
• 1:17
  Speaker 4: be that. These tours are pretty regular occasions, as you
• 1:21
  Speaker 4: know from Marny's Dark Sky Traveler Company. I do the science.
• 1:25
  Speaker 4: She does all the real work. But this will be
• 1:28
  Speaker 4: the first time we've included Greenland in one of these,
• 1:30
  Speaker 4: so we're hoping for very spectacular views of Iceberg's as
• 1:34
  Speaker 4: well as spectacular views of the Northern Lights.
• 1:37
  Speaker 2: Getting American visa yet for Greenland, it's okay.
• 1:42
  Speaker 4: Our Mary won't let it go. I can tell you.
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  Speaker 1: Yeah, well, I'm Judy and I are visiting Greenland later
• 1:50
  Speaker 1: this year, so we won't know who's actually controlling.
• 1:56
  Speaker 4: We'll let you know what it's like.
• 1:57
  Speaker 1: Yeah, but I've got my US exemptions, so I should
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  Speaker 1: be right. Okay, Shall we get straight into it?
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  Speaker 2: Why not? All right?
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  Speaker 1: Our first question comes from somebody who's never sent a
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  Speaker 1: question in before except for the other twenty five times.
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  Speaker 1: Rusty from Donnybrook.
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  Speaker 3: True, Andrew, Okay, it's rusty.
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  Speaker 2: A question about black holes.
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  Speaker 3: If a primordial black hole comparable with the size of
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  Speaker 3: the Earth were to enter the Solar System at a
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  Speaker 3: high angle to the ecliptic and impact one of the
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  Speaker 3: rocky planet directly, would it a path through largely unnoticed,
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  Speaker 3: b leave a huge hole through the center of the planet,
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  Speaker 3: which would cause a lot of mayhem, or c explode
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  Speaker 3: the planet completely.
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  Speaker 2: Or d none of the above heavy hand in.
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  Speaker 1: I should tell you Johnty that Rusty has a hebit
• 3:10
  Speaker 1: of throwing curveballs at us. He's always trying to trick Fred.
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  Speaker 1: So just bear that in mind when we try and
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  Speaker 1: tackle this one.
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  Speaker 2: Well, so I've got a qualification request, Sick. You get
• 3:21
  Speaker 2: two very different answers depending on minutia here, because he
• 3:24
  Speaker 2: says it's the size of the Earth. But if it's
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  Speaker 2: the size of the Earth, then it's two two hundred
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  Speaker 2: times the mass of the Sun, a black hole the
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  Speaker 2: tip of the Earth. If it's a black hole the
• 3:35
  Speaker 2: mass of the Earth, then it's nine millimeters across. And
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  Speaker 2: so you get a very different outcome depending on which
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  Speaker 2: of those it is. I mean, either way, you're going
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  Speaker 2: to change the orbits of the planets, particularly the one
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  Speaker 2: that it encounters. But if it's the size of the
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  Speaker 2: Earth and left or twenty two hundred times the mass
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  Speaker 2: of the Sun, the Solar system will be utterly disrupted,
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  Speaker 2: the planets will be ejected, the thing it hits will
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  Speaker 2: just kind of mean, and it's mass will have gone
• 4:01
  Speaker 2: up a tiny little amount. If it's the mass of
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  Speaker 2: the Earth and left on nine millimeters across. We probably
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  Speaker 2: wouldn't see it coming, we'd see the orbits changing. It
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  Speaker 2: will probably punch a nine millimeter sized hole through the Earth,
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  Speaker 2: but there's not really any friction let to slow it down.
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  Speaker 2: So I don't know that you get much in the
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  Speaker 2: way of recoil, but you would get a gravitational perturbation
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  Speaker 2: change in the Earth's orbit, that'd be my take. So
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  Speaker 2: if it came through the Earth, our orbit will become
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  Speaker 2: more tilted, seasons would be more pronounced. You'd also have
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  Speaker 2: a fairly dramatic change in where the planets are in
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  Speaker 2: the sky and all that stuff. If it was twenty
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  Speaker 2: two hundred times a mass of the Sun, this will
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  Speaker 2: be the last podcast.
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  Speaker 4: Yeah, I think so. Yeah, my take on it is
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  Speaker 4: pretty well what yours is, John T. I just assumed
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  Speaker 4: it was the mass of the Earth we were talking about,
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  Speaker 4: and I think it's the radius of the event horizon.
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  Speaker 4: That's nine millimeters of an Earth sized and Earth mass
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  Speaker 4: black hole. But something that size, I mean, you know,
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  Speaker 4: you said in the intro to this, Andrew that it
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  Speaker 4: was Rusty throwing a curveball, and that's what it's going
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  Speaker 4: to be. It would be. It probably wouldn't be a
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  Speaker 4: direct hit, because those are quite rare, it would, but
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  Speaker 4: it would still be near enough to a direct hit
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  Speaker 4: that the orbit of the black hole would you know,
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  Speaker 4: if it came close enough to the Earth, the tidal
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  Speaker 4: effects on the Earth itself would be disastrous, one side
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  Speaker 4: of the Earth feeling much more of a pool than
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  Speaker 4: the other side. So yeah, effectively we would still be spaghettified,
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  Speaker 4: and maybe a bit slower than you would if you
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  Speaker 4: just fell into a black hole yourself. But it would
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  Speaker 4: be a fairly disastrous scenario as well as you know,
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  Speaker 4: perturbing the orbits of the other planets.
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  Speaker 2: It will be a mess.
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  Speaker 4: So I think it's d isn't it. None of the
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  Speaker 4: above is the correct answer.
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  Speaker 2: And the other one with it with the Earth and Moon, though,
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  Speaker 2: will be because of the way the Earth and Moon
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  Speaker 2: move if it came through you know, if it's more
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  Speaker 2: than two or three times the Earth idiots away. We're
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  Speaker 2: not going to be disrupted, but we will have big
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  Speaker 2: tidle effects. But the Earth and the Moon will be
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  Speaker 2: pulled by different amounts in different directions, and so it
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  Speaker 2: might be enough to dissociate the Earth and Moon and
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  Speaker 2: suddenly we'll have five planets not four in the MSSL system,
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  Speaker 2: with the added impact that down the line the Earth
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  Speaker 2: and the Moon might colyde, and that will be yet
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  Speaker 2: another bad day.
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  Speaker 1: Indeed, on the flood slide, golfers be thrilled because it
• 6:24
  Speaker 1: would increase their chances of a whole in one significantly.
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  Speaker 1: Oh dear, all right, Rusty, thanks for that one. You're
• 6:33
  Speaker 1: always throwing one out there, and that certainly did apply
• 6:38
  Speaker 1: in this case. Our next question comes from Marcel. Science
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  Speaker 1: currently holds the belief that our universe is thirteen point
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  Speaker 1: eight billion years old. The James Web Space Telescope keeps
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  Speaker 1: on finding older and older galaxies. Some of the oldest
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  Speaker 1: galaxies observed are believed to have formed over three hundred
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  Speaker 1: million years after the Big Bang. What if we find
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  Speaker 1: a galaxy that is fourteen million years old? How will
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  Speaker 1: we begin to adjust our theories to match reality. Which
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  Speaker 1: theories will be first to get thrown out the window
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  Speaker 1: versus which theories do we believe are absolutely correct?
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  Speaker 4: Can I have a shot at this? Yeah, the it's
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  Speaker 4: not going to happen. We'll find a galaxy older than
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  Speaker 4: the universe. It actually, in the early days of the
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  Speaker 4: Big Bang theory that was one of the problems that
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  Speaker 4: our measurements then suggested that the Big Bang occurred more
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  Speaker 4: recently than the ages of the planets and the stars,
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  Speaker 4: that you know, you have a universe that's younger than
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  Speaker 4: its contents, and that's clearly not a possibility. And it
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  Speaker 4: was only when we really worked out just how all
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  Speaker 4: the universes and our current thinking is indeed thirty point
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  Speaker 4: eight billion years, that was all rectified. But the bottom
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  Speaker 4: line is that the yardstick by which the a of
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  Speaker 4: galaxies is measured is basically as a fraction of the
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  Speaker 4: age of the universe. So you're never going to find
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  Speaker 4: a galaxy that's older than the universe, because you're sort
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  Speaker 4: of you know, you're looking back certainly perhaps ninety percent,
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  Speaker 4: ninety five percent of the age of the universe for
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  Speaker 4: some of these some of these really primitive galaxies that
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  Speaker 4: we're seeing. But it's never going to be older than
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  Speaker 4: the universe because we can't. We define it as essentially
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  Speaker 4: a fraction of the universe's age, so that won't happen.
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  Speaker 4: What is more interesting is the souphilety of this, which
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  Speaker 4: is that we do see galaxies which are seen as
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  Speaker 4: the universe was as it was when it was only
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  Speaker 4: perhaps two or three hundred million years old, which look
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  Speaker 4: more mature than we expected them to be. We see
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  Speaker 4: black holes that are bigger than we expected them to be,
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  Speaker 4: because we thought they'd take a lot longer to grow
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  Speaker 4: to their supermassive size. So those are the conundrums, not
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  Speaker 4: that we're going to find a galaxy that's older than
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  Speaker 4: the universe, but trying to understand how it is that
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  Speaker 4: some of these phenomena that we see spiral arms, for example,
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  Speaker 4: occurred so quickly in the early history of the universe.
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  Speaker 1: I suppose his point was that, you know, if we
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  Speaker 1: find something that's so close to when the universe began,
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  Speaker 1: how do you equate for that.
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  Speaker 4: Well, that's the bottom line, is what I was just saying.
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  Speaker 4: You know, it means we have to revise our ereas
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  Speaker 4: of galaxy evolution, not that we have to throw away
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  Speaker 4: the Big Bang, which is what a lot of his
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  Speaker 4: questions are aiming at. The Big Bang is absolutely secure.
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  Speaker 4: We can still see it, you know, we know that
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  Speaker 4: it happened.
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  Speaker 1: And yet we get people questioning us on it.
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  Speaker 2: Fred semi regularly.
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  Speaker 1: There are quite a few people who don't believe in it.
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  Speaker 4: Well, neither did my namesake, Fred Hoyle. He was a
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  Speaker 4: staunch believer in the study state theory until he went
• 9:51
  Speaker 4: to his grave.
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  Speaker 2: Yeahs, Johnny, Well that's interesting, Paralleskca. The other thing that
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  Speaker 2: comes into this is uncertainty, which is we never measure
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  Speaker 2: an edge with perfect precision. There's always a bit of
• 10:02
  Speaker 2: an error bar on it. And I'm reminded of the
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  Speaker 2: story probably about a decade ago, of that star that
• 10:06
  Speaker 2: people dubbed the Methusela Start, which is HD one four
• 10:10
  Speaker 2: zero two eighty three lovely Barcode, and that made news
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  Speaker 2: back in like twenty thirteen because people had measured its age.
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  Speaker 2: It's an incredibly metal pole star. It's one of the
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  Speaker 2: oldest stars in the galaxy for certain but they'd measured
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  Speaker 2: the age based on all these observations of it and
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  Speaker 2: estimated an age of fourteen point four to six plus
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  Speaker 2: and minus zero point eight billion years, and that age
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  Speaker 2: is older than the edge of the universe. So people
• 10:34
  Speaker 2: were saying, how can we have a star older than
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  Speaker 2: the edge of the universe. And the subtlety here is
• 10:39
  Speaker 2: in the uncertainty on the measurement, because that plus or
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  Speaker 2: minus zero point eight billion years is saying that in
• 10:46
  Speaker 2: sixty six percent of cases this is one sigma era,
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  Speaker 2: so sixty six percent of the time the age will
• 10:51
  Speaker 2: fall in that age range and thirty three percent of
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  Speaker 2: the time it will fall outside of age range. So that
• 10:57
  Speaker 2: age is compatible with the edge of the universe. And
• 10:59
  Speaker 2: it's just telling you that this star is very old.
• 11:02
  Speaker 2: It's not saying the stars older than the edge of
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  Speaker 2: the universe necessarily. And what's actually happening in the follow
• 11:07
  Speaker 2: up from that is a couple of more recent studies
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  Speaker 2: have given it ages of thirteen point seven or twelve
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  Speaker 2: billion years. So as we've got more data, the arabar
• 11:16
  Speaker 2: has shrunk, but it's noticeable that it's that age has
• 11:18
  Speaker 2: moved by more than a single Arabar, which is not
• 11:21
  Speaker 2: uncommon when the errors are quite large. Other than that,
• 11:25
  Speaker 2: it is, like Fred says, the problem is that even
• 11:27
  Speaker 2: if you change the edge of the universe a little bit,
• 11:29
  Speaker 2: these galaxies will still have formed within the first two
• 11:32
  Speaker 2: percent or five percent of its life. You're just stretching
• 11:35
  Speaker 2: the timeline or shrinking the timeline a little bit. It's
• 11:38
  Speaker 2: like what we talked about in the other podcasts, the
• 11:42
  Speaker 2: way that theory and observation interact is that theory is
• 11:45
  Speaker 2: the best possible explanation of what we've already seen, and
• 11:48
  Speaker 2: it predicts what we should see in the future with
• 11:49
  Speaker 2: better instruments. And when those better instruments give us new measurements,
• 11:54
  Speaker 2: that allows us to refine or improve, or disprove or
• 11:57
  Speaker 2: kill the theory. You know, there's an argument you can
• 11:59
  Speaker 2: never prove the theory, but you can disprove it, and
• 12:02
  Speaker 2: the more you fail to disprove it, the more confident
• 12:05
  Speaker 2: we are that it's a good theory. And in this case,
• 12:08
  Speaker 2: is telling us not that the Big Bang theory is wrong.
• 12:11
  Speaker 2: It's not telling us that the universe wasn't from that way,
• 12:13
  Speaker 2: but instead it's telling us that our understanding of how
• 12:16
  Speaker 2: stars and galaxies form in those early days is incomplete.
• 12:20
  Speaker 2: And that's exactly why people wanted these incredible telescopes to
• 12:24
  Speaker 2: go up there, because that's the only way we can
• 12:25
  Speaker 2: find it out.
• 12:27
  Speaker 1: And I suppose we have to keep making adjustments for
• 12:29
  Speaker 1: the fact that we've decided all this because of two
• 12:31
  Speaker 1: ki layers of mush inside.
• 12:33
  Speaker 2: Ere yes, so messing what a little bit of do
• 12:37
  Speaker 2: we carbon can do.
• 12:39
  Speaker 4: It's the it's the one hundred billion neurons in it
• 12:42
  Speaker 4: the checky bit.
• 12:43
  Speaker 1: Yes, thanks mars O. Great question, always a good discussion
• 12:48
  Speaker 1: point that one. This is Space Nuts with Andrew Dunkley,
• 12:51
  Speaker 1: Professor Freed Watson, and Professor John E.
• 12:53
  Speaker 2: Horna.
• 12:56
  Speaker 1: Okay, we take all for Space Nuts and.
• 13:00
  Speaker 2: John Ty we have movement. We have movement.
• 13:02
  Speaker 1: I see a dog with it who is coming over
• 13:06
  Speaker 1: to say to you, Yeah, what's his name?
• 13:09
  Speaker 2: That's Maya. That's the sister. We've got a brother and
• 13:11
  Speaker 2: sister who are coming to eight years old. But she's
• 13:13
  Speaker 2: the modult she's heading off to see if there's anything
• 13:17
  Speaker 2: interesting happening elsewhere. Yes, nothing interesting happening here. That's which I.
• 13:24
  Speaker 1: Let's go to our next question. This is an Alredio
• 13:26
  Speaker 1: a question from one of our regular contributors.
• 13:29
  Speaker 5: Hello buddy, Hello spaces buddy from Oregon. Again, Hey guys,
• 13:33
  Speaker 5: would the center of a galaxy be like the ultimately
• 13:36
  Speaker 5: Grange point like for the galaxy you were saying your
• 13:39
  Speaker 5: first had a tunnel in it that once you got
• 13:42
  Speaker 5: in the middle you would be weightless. That be like
• 13:44
  Speaker 5: a Grange point zero. And if so, wouldn't that make
• 13:48
  Speaker 5: the black hole weightless to the galaxy? And would that
• 13:53
  Speaker 5: no point in the center from the little grange point
• 13:56
  Speaker 5: create a gravitational Well, that look like your donut that
• 14:01
  Speaker 5: you were talking about in the galaxy? Were the gravitation
• 14:03
  Speaker 5: all right? Thanks guys of the podcast, keep up the
• 14:05
  Speaker 5: good work.
• 14:07
  Speaker 1: Got a big glucchy there, d and Buddy, but that's
• 14:09
  Speaker 1: the Internet for you. Thanks for the question the ultimate
• 14:12
  Speaker 1: lagrange point? Would the center of the galaxy be the
• 14:16
  Speaker 1: ultimate lagrange point?
• 14:18
  Speaker 2: Who wants to take a that one first? I can
• 14:20
  Speaker 2: dive in briefly if you want. So. The background here
• 14:25
  Speaker 2: is that the lagrange points are local areas of increased stability,
• 14:30
  Speaker 2: and it comes out of something called the restricted three
• 14:32
  Speaker 2: body problem, where you've got in the Solar system, which
• 14:35
  Speaker 2: is where I do a lot of my work, the
• 14:36
  Speaker 2: Sun and the planet and something else, and that something
• 14:40
  Speaker 2: else is pretty small and tiny, and you can play games.
• 14:44
  Speaker 2: So when I was a kid, I was in Scouts
• 14:46
  Speaker 2: and we used to go out in the countryside and
• 14:48
  Speaker 2: we had contour maps, which were maps of the local
• 14:51
  Speaker 2: area that had these lines on and they told you
• 14:52
  Speaker 2: how high or how low you were, And what those
• 14:55
  Speaker 2: contours are actually is telling you what your gravitational potential
• 14:58
  Speaker 2: energy is. It's a measure of the gravity potential. You
• 15:02
  Speaker 2: can do the same with the Solar system. You can
• 15:03
  Speaker 2: make a map of the Solar system that is like
• 15:05
  Speaker 2: a contour map, and when you do that, you find
• 15:09
  Speaker 2: the Sun's a big well in the middle, and the
• 15:11
  Speaker 2: Earth's a smaller mole where the Earth is. But there
• 15:13
  Speaker 2: are five locations where you have local plateaus, local flatbits,
• 15:18
  Speaker 2: and there you're lagrange points, and they're more realistically LaGrande areas,
• 15:23
  Speaker 2: and three of them are like sabbles on a hillside,
• 15:26
  Speaker 2: so they're fairly stabled, but if you roll a little
• 15:28
  Speaker 2: where you'll fall off. And that's lagrange one, two, and three,
• 15:31
  Speaker 2: and they're on the line between the Sun and the Earth.
• 15:34
  Speaker 2: One is on the far side of the Sun, one
• 15:37
  Speaker 2: is between the Earth and Sun, and one is just
• 15:38
  Speaker 2: on the far side of the Earth on that line.
• 15:40
  Speaker 2: The other two lagrange points four and five, which are
• 15:43
  Speaker 2: like these big plateaus that are sixty degrees ahead and
• 15:46
  Speaker 2: behind the Earth and its orbit, or behind Jupter in
• 15:48
  Speaker 2: its orbit. That's where you get the Jupeter trojans. And
• 15:51
  Speaker 2: so these are points where the contours are flattered, so
• 15:54
  Speaker 2: you can sit there fairly stable before you roll off
• 15:56
  Speaker 2: in any given direction. The middle of the Sun in
• 16:00
  Speaker 2: that analogy isn't a lagrange point if that's a slightly
• 16:03
  Speaker 2: different concept. So you are entirely right that if you're
• 16:06
  Speaker 2: in the middle of an object, you don't feel any
• 16:09
  Speaker 2: gravitational pull from that object. More strictly, you feel the
• 16:12
  Speaker 2: gravitational pull from every atom individually, but they all cancel out.
• 16:16
  Speaker 2: So if you're in the middle of the Earth, you're
• 16:17
  Speaker 2: being pulled by people study in America the same amount
• 16:21
  Speaker 2: as you are by people stood in Australia, but they're
• 16:23
  Speaker 2: pulling an opposite direction, so it all cancels out. So
• 16:26
  Speaker 2: if you were in the middle of the black hole
• 16:29
  Speaker 2: and ignoring all the other issues that would entail, you
• 16:32
  Speaker 2: wouldn't feel the gravitational pull of the black hole. And
• 16:35
  Speaker 2: if that was exactly at the center of the galaxy,
• 16:38
  Speaker 2: all the mass in the galaxy would cancel out, but
• 16:40
  Speaker 2: you'd still feel the pull from things locally. So if
• 16:43
  Speaker 2: you were in the middle of the Earth and you
• 16:45
  Speaker 2: were massless from the point of view of the Earth,
• 16:47
  Speaker 2: you'd still feel the pull from the Moon in one
• 16:49
  Speaker 2: direction and the Sun in the other direction. You'd still
• 16:51
  Speaker 2: feel all those things, so you would be still being
• 16:53
  Speaker 2: pulled around. And I dare say that you'd probably be
• 16:57
  Speaker 2: pulled slightly off center if you could move around when
• 17:00
  Speaker 2: you'd sad feel the pull from the gravitation as the
• 17:02
  Speaker 2: black hole pulling you back towards the middle, and the
• 17:04
  Speaker 2: further out you go, the more pull you feel, because
• 17:06
  Speaker 2: you only feel the pull from the stuff that is
• 17:09
  Speaker 2: interior to you everything. And this used to make my
• 17:12
  Speaker 2: head hurt when we did electromagnetism at UNI and trying
• 17:15
  Speaker 2: to get your head around this. Everything more distant from
• 17:18
  Speaker 2: the middle than you are cancels out with everything else.
• 17:22
  Speaker 2: Everything nearer to the middle you feel added up, as
• 17:25
  Speaker 2: though it's pulling from the center. So technically it wouldn't
• 17:28
  Speaker 2: be a grand point because it's not one of those plateaus.
• 17:31
  Speaker 2: It's the bottom of a well instead, But it would
• 17:34
  Speaker 2: be a place where you would effectively be weightless massless.
• 17:38
  Speaker 2: What weightless rather than massless is a technical thing. You
• 17:41
  Speaker 2: still have mass, but there'd be nothing pulling on you,
• 17:43
  Speaker 2: so you wouldn't have weight, but it wouldn't count as
• 17:46
  Speaker 2: the grande point from my point of.
• 17:47
  Speaker 1: View, until you turned into spaghetti.
• 17:51
  Speaker 2: Steve would be the same thing, and it will probably
• 17:53
  Speaker 2: be a lot of pain as you become spagetified. Yes,
• 17:56
  Speaker 2: as you do to get there.
• 17:58
  Speaker 4: You're to get there, that's right. So that absolutely, John
• 18:03
  Speaker 4: T so that I think that means the the answer
• 18:06
  Speaker 4: the question is is just yes, except we don't consider,
• 18:12
  Speaker 4: you know, the center of things as being at the
• 18:14
  Speaker 4: graunge point. It's the graunge points are quite specific, or
• 18:18
  Speaker 4: areas is a much better term for them, because they're
• 18:21
  Speaker 4: you know, we think of them as an individual point
• 18:23
  Speaker 4: in space, but they're not. They're far from it. That's why,
• 18:26
  Speaker 4: for example, the L two point in the Earth, the
• 18:30
  Speaker 4: GROUNDE system, it can be occupied by many spacecraft at once,
• 18:33
  Speaker 4: which it.
• 18:34
  Speaker 1: Is, yes, and it's not like did steal The spacecraft
• 18:39
  Speaker 1: have to adjust to the load.
• 18:41
  Speaker 2: And that's because they're starting to roll off the saddle.
• 18:43
  Speaker 2: So these halo orbits that they move around are actually
• 18:46
  Speaker 2: rolling around the saddle essentially along a line of constant
• 18:50
  Speaker 2: high like one of those contours on your contour MAPP.
• 18:53
  Speaker 2: But it's very easy to roll off. So that's why
• 18:55
  Speaker 2: you burn fuel to stay on location. Because with the
• 18:58
  Speaker 2: Alto in particular, if you fall off, you'll eventually fall
• 19:01
  Speaker 2: off properly because he've been pulled by everything else. Yeah,
• 19:04
  Speaker 2: and land in a pile of dirt, which is what
• 19:05
  Speaker 2: happened when I rolled up the saddle once. But was like,
• 19:08
  Speaker 2: go there, I was not injured. I wasn't really injured.
• 19:12
  Speaker 4: You're very lucky. Yeah, it was very people to get injured.
• 19:16
  Speaker 2: Thank you, buddy.
• 19:17
  Speaker 1: So yeah, as always, I love the way Buddy thinks.
• 19:20
  Speaker 2: He comes up with his amazing ideas.
• 19:22
  Speaker 1: I don't know where he his brain is obviously going
• 19:26
  Speaker 1: at ten thousand miles an hour all the time.
• 19:28
  Speaker 2: It comes up with some interesting questions.
• 19:30
  Speaker 1: Our last question today comes from Michael in Evanston, Illinois. Gentleman, Greetings,
• 19:36
  Speaker 1: Regarding the expansion of the universe, it is my understanding
• 19:39
  Speaker 1: that an accelerating expansion means that everything in the universe
• 19:43
  Speaker 1: is moving apart faster and faster. This means that eventually
• 19:47
  Speaker 1: nothing will be visible from anywhere else. Does this mean
• 19:50
  Speaker 1: that the planets in our Solar system are moving apart
• 19:53
  Speaker 1: and that our moon is moving apart from Earth due
• 19:57
  Speaker 1: to the universe's expansion. Notwithstanding what we talked about in
• 20:02
  Speaker 1: the last episode regarding a new theory about the expansion
• 20:06
  Speaker 1: of the universe and dark matter, let's stick with the
• 20:09
  Speaker 1: model that we all agree on at the moment. And look,
• 20:13
  Speaker 1: he's right, it is expanding.
• 20:14
  Speaker 2: Everything's moving apart. But there are other factors in play,
• 20:18
  Speaker 2: aren't they for it?
• 20:19
  Speaker 4: Indeed, it's a gravity that dominates on the scale of
• 20:23
  Speaker 4: the Solar System. We can't feel the expansion of the
• 20:25
  Speaker 4: universe on the scale of the Solar System is too small,
• 20:29
  Speaker 4: and gravity is the overwhelmingly important force. It's only when
• 20:32
  Speaker 4: you get out to you know, you start looking at
• 20:34
  Speaker 4: objects which are perhaps more than ten twenty million light
• 20:38
  Speaker 4: years away, before you start seeing that expansion. Never mind
• 20:42
  Speaker 4: the accelerated expansion. And even if the accelerated expansion does
• 20:46
  Speaker 4: continue until we get the big rip, which is what
• 20:50
  Speaker 4: some people think might happen, it's going to be a
• 20:53
  Speaker 4: long time before the distance from the Earth to the
• 20:56
  Speaker 4: Moon is affected by that particular geometry. Gravity is the force.
• 21:01
  Speaker 2: Well I had clarified for me, and there's all these
• 21:06
  Speaker 2: kind of things. Is where that boundary comes. So there
• 21:08
  Speaker 2: is other local scale of the scale of the Milky Way.
• 21:11
  Speaker 2: Even gravity wins. So the Milky Way gets held together.
• 21:14
  Speaker 2: The local cluster should get hell together as well. But
• 21:17
  Speaker 2: I don't know where the threshold is where it doesn't
• 21:19
  Speaker 2: because the local cluster is part of a bigger cluster
• 21:21
  Speaker 2: which is part of a supercluster, and at some point
• 21:25
  Speaker 2: you have this boundary where expansion wins, but if it
• 21:30
  Speaker 2: has to be link to that cluster structure, So it
• 21:32
  Speaker 2: can't be halfway across a supercluster, because something halfway across
• 21:36
  Speaker 2: the supercluster is still attracted to its neighbors. So it
• 21:39
  Speaker 2: comes down to the voids and everything else. And nobody's
• 21:43
  Speaker 2: been able to give a definitive, essentially horizon where things
• 21:47
  Speaker 2: will stay closer to us or where things will move away.
• 21:50
  Speaker 2: So I guess we just don't know that yet. We
• 21:52
  Speaker 2: don't have a deep enough foundational enough knowledge of the
• 21:55
  Speaker 2: structure of matter on that kind of scale near as
• 21:57
  Speaker 2: to know. But I think the event horizon is of
• 22:00
  Speaker 2: that kind of scale of the Verger cluster will still
• 22:03
  Speaker 2: be just about there. But the more distant structure one,
• 22:06
  Speaker 2: I don't know where that threshold is.
• 22:08
  Speaker 4: It's probably a very wiggly one because it's going to
• 22:11
  Speaker 4: follow the you know, the inhomogeneity of what we see
• 22:14
  Speaker 4: around us in our local part of the universe. It's yeah,
• 22:20
  Speaker 4: it's a good point that you know, we can't say, well,
• 22:23
  Speaker 4: beyond fifty million light years, you're going to see the
• 22:26
  Speaker 4: expansion dominating because it will depend exactly on the on
• 22:31
  Speaker 4: the presence. I mean, it throws back to one of
• 22:35
  Speaker 4: the hot topics twenty years ago, which was the Great Tractor.
• 22:39
  Speaker 4: The greater tractor being this thing hidden behind the Milky
• 22:41
  Speaker 4: Way that we believe now is a part of a
• 22:45
  Speaker 4: supercluster of galaxies that seem to be pulling everything towards it,
• 22:49
  Speaker 4: but it's only one particular direction. So you've got that
• 22:53
  Speaker 4: kind of thing going on all around us and at
• 22:56
  Speaker 4: different distances. So yes, it would be a week, you know,
• 23:00
  Speaker 4: thinking back to those contours you were talking about and
• 23:02
  Speaker 4: minutes ago, Johnty. It's a contour, but it's a very
• 23:05
  Speaker 4: wiggling one. I think I have.
• 23:07
  Speaker 2: One heritage of this as well. I always love these
• 23:10
  Speaker 2: things where we detect something in directly. That's what we
• 23:13
  Speaker 2: do with excel planets now. It's how Neptune was found.
• 23:16
  Speaker 2: So we've got several hundred years of inferring that something
• 23:20
  Speaker 2: exists when we can't see it because it's effect on
• 23:23
  Speaker 2: something else. And the Great attract is just another in
• 23:25
  Speaker 2: a long list of we can't see it, but we
• 23:27
  Speaker 2: know it's because we see what it does to everything else.
• 23:33
  Speaker 1: Yeah, the greater you've enabled me to relyve a really
• 23:37
  Speaker 1: old dead joke, but the greater attractory the messy Ferguson
• 23:40
  Speaker 1: because my uncle used to work for their company, but
• 23:44
  Speaker 1: part right.
• 23:46
  Speaker 2: And as far as.
• 23:47
  Speaker 1: Expansions concern, expansion wins. When you wait turn many donuts,
• 23:52
  Speaker 1: you're just feeding me.
• 23:53
  Speaker 2: Too much information to work with. So this is why
• 23:56
  Speaker 2: I'm gradually resembling Patrick more more and more, because that's
• 23:59
  Speaker 2: growing vertict when I was thirteen, and I've just been
• 24:01
  Speaker 2: expanding horizontally ever since.
• 24:03
  Speaker 4: Just don't espouse his politics, that's all.
• 24:06
  Speaker 2: John t oh No, absolutely not. I leaned so far left.
• 24:10
  Speaker 2: I'm horizontal like many acts great space nuts. Andrew.
• 24:20
  Speaker 4: I was going to say, you know, this is a
• 24:22
  Speaker 4: Q and A session. Can I thrown a question for
• 24:26
  Speaker 4: John t Uni questions right, because I'm not going to
• 24:31
  Speaker 4: be around for the next episode, So i just want
• 24:34
  Speaker 4: to know what Johnny's take on Planet nineties.
• 24:37
  Speaker 2: Oh yes, it is really interesting. So the first paper
• 24:40
  Speaker 2: I ever published, back when I was doing my PhD,
• 24:43
  Speaker 2: was debunking one of the many variants of Planet X.
• 24:47
  Speaker 2: And this is a recurring theme that comes up about
• 24:50
  Speaker 2: every fifteen or twenty years when we get better data
• 24:52
  Speaker 2: on things that are pushing the limits of our understanding
• 24:54
  Speaker 2: of the SOL system. So in the early nineteen eighties
• 24:57
  Speaker 2: you have Nemesis, which was Richard muller hypothesis of a
• 25:02
  Speaker 2: brown dwarf or a red dwarf orbiting the Sun on
• 25:05
  Speaker 2: a twenty six million year orbit that was giving us
• 25:07
  Speaker 2: comets killing cosmats extinctions, and that even though it's sums
• 25:12
  Speaker 2: sound now, at the time it was a reasonable possibility
• 25:15
  Speaker 2: as an explanation of the data. That made a prediction
• 25:18
  Speaker 2: which was if it's there, you'll see it. And then
• 25:20
  Speaker 2: we didn't see it. We got good enough satellites to
• 25:22
  Speaker 2: do it, and so that died away. And then back
• 25:25
  Speaker 2: when I sat on my PhD in two thousand, there
• 25:28
  Speaker 2: was a regurgitation of the idea, in this case being
• 25:32
  Speaker 2: planet X, because Pluto at that point hadn't yet rightfully
• 25:35
  Speaker 2: been demotored, so people still counted it with a grimace.
• 25:40
  Speaker 2: But looking at the data of where comets come in
• 25:43
  Speaker 2: towards the Sun from, so not their perihelium, which is
• 25:46
  Speaker 2: where their closest to some but where on the sky
• 25:48
  Speaker 2: their app helium would be, they're furthest from the Sun.
• 25:51
  Speaker 2: There were suggestions that there was a bit of an
• 25:54
  Speaker 2: enhancement of comets coming from a great surf on the sky.
• 25:57
  Speaker 2: So one particular ring three hundred and sixty grees round
• 26:00
  Speaker 2: the sky had more comets than any other, and there
• 26:03
  Speaker 2: were two papers identifying this. The twist was that both
• 26:06
  Speaker 2: of them had great circles that were at right angles
• 26:08
  Speaker 2: to each other. That didn't agree. So the first thing
• 26:12
  Speaker 2: I did in my PhD was look at all this
• 26:14
  Speaker 2: and say, well, hang on, our discoveries of comets are
• 26:17
  Speaker 2: biased by the fact that we see them when they
• 26:19
  Speaker 2: near the sun, we see them at certain months, we
• 26:21
  Speaker 2: see them from the northern hemispheres, where all these different
• 26:24
  Speaker 2: biases you put them in and both great circles disappear.
• 26:27
  Speaker 2: So it was actually a result of our observational biases,
• 26:30
  Speaker 2: and so that one went away as we got more data.
• 26:33
  Speaker 2: And then what's happened over the last decade or so
• 26:36
  Speaker 2: is that our ability to find small objects in the
• 26:39
  Speaker 2: outer Soul system has got better and better. So we're
• 26:41
  Speaker 2: starting to find things out beyond the nominal edge of
• 26:45
  Speaker 2: the edge with Koliper belt, beyond about fifty AU. And
• 26:49
  Speaker 2: these are objects that are far enough aware that the
• 26:52
  Speaker 2: influence of the planets isn't enough to modify their orbits
• 26:57
  Speaker 2: in any real sense. But there has been a set
• 27:01
  Speaker 2: of detections of objects further out that a bit like
• 27:04
  Speaker 2: that great circle appeared to be more likely to be
• 27:07
  Speaker 2: found in one part of the sky than anywhere else. Now,
• 27:10
  Speaker 2: one explanation for that is that there is something that
• 27:13
  Speaker 2: we haven't seen that's further out, that is stirring them
• 27:15
  Speaker 2: up and has corralled them, and that works really well
• 27:18
  Speaker 2: to explain what we see. Another explanation is that this
• 27:22
  Speaker 2: is in art factor of the observational bias. Because the
• 27:25
  Speaker 2: survey is primarily done by the Canada, France Hawaii Telescope,
• 27:29
  Speaker 2: which sees Northern Hemisphere sky by preference to southern Hemisphere
• 27:34
  Speaker 2: has a varying cycle of cloudiness through the year, it's
• 27:37
  Speaker 2: hard to find these things where the Milky Way is,
• 27:39
  Speaker 2: so there are some people arguing that this will turn
• 27:41
  Speaker 2: out to be an observational bias. You've also got a
• 27:44
  Speaker 2: few different versions of planet X being proposed. So the
• 27:48
  Speaker 2: most famous one is the one that gets talked about
• 27:51
  Speaker 2: a lot, which is batting and people like that talking
• 27:54
  Speaker 2: about a fairly massive Planet X. But a really good
• 27:56
  Speaker 2: friend of mine who actually visited me at Unisq, a
• 27:59
  Speaker 2: couple of mon Patrick Soephi La Kafka from Japan has
• 28:03
  Speaker 2: been quietly running simulations looking at an Earth mass object,
• 28:07
  Speaker 2: which would work from the point of view of our
• 28:10
  Speaker 2: understanding of the formation of the giant planets. You would
• 28:12
  Speaker 2: have formed a lot of objects out size that were
• 28:14
  Speaker 2: then ejected that weren't incorporated, some of which will have
• 28:17
  Speaker 2: been ejected but not fully ejected, so you could have
• 28:20
  Speaker 2: Earth sized objects in the old cloud quite reasonably. And
• 28:24
  Speaker 2: he's been looking at the distributions of all these things
• 28:27
  Speaker 2: beyond Neptune. If you had something the mass of the
• 28:29
  Speaker 2: Earth two or three or four hundred au away that
• 28:32
  Speaker 2: we couldn't cannotly detect, but we'll be able to find
• 28:34
  Speaker 2: in the next five or ten years. And that does
• 28:37
  Speaker 2: a really good job of explaining the groups of objects
• 28:40
  Speaker 2: we can't currently explain. Doesn't mean it's right. What it's
• 28:45
  Speaker 2: doing is saying, here is something we can't explain observationally.
• 28:48
  Speaker 2: Here's a couple of different teams proposing hypotheses that there
• 28:51
  Speaker 2: were a really good job of fitting the data and
• 28:54
  Speaker 2: explaining what we otherwise can't do. And they then make
• 28:57
  Speaker 2: a prediction in both cases, which is, as Vera Rooms
• 29:00
  Speaker 2: comes online, this incredible new observatory that's going to increase
• 29:03
  Speaker 2: the number of objects we know by a factor of
• 29:05
  Speaker 2: ten to one hundred times. In the Solar system, we'll
• 29:08
  Speaker 2: certainly have a lot more data, and if these series
• 29:11
  Speaker 2: are correct, these data will support them. If not, they'll
• 29:15
  Speaker 2: shoot them down. Now, I think given the past history
• 29:18
  Speaker 2: of Nemesis and Planet X, people are understandably very skeptical,
• 29:23
  Speaker 2: but it's very good science been done by really reputable
• 29:26
  Speaker 2: scientists who are not saying this is definitely there. They're saying,
• 29:30
  Speaker 2: here's something we cannot explain. Here is one way of
• 29:33
  Speaker 2: explaining it that works really well and fits with the
• 29:37
  Speaker 2: observational contracts we can only have. The truth could be
• 29:40
  Speaker 2: out there, you know, it's kind of X file thing,
• 29:43
  Speaker 2: but we won't know until we get more data. When
• 29:46
  Speaker 2: that data comes in, this is what we should look for.
• 29:48
  Speaker 2: And that's really important because if you do some modeling,
• 29:52
  Speaker 2: and some Solar system groups have done this in the
• 29:54
  Speaker 2: past with very famous models that explain very well what
• 29:57
  Speaker 2: we currently see but nothing else. They don't make predictions
• 30:01
  Speaker 2: of what we don't currently see. Then that to me
• 30:04
  Speaker 2: stamp collecting. It's not actually science because there's an infinite
• 30:07
  Speaker 2: number of ways of explaining what we can only see.
• 30:10
  Speaker 2: And what both these models are doing really well is
• 30:12
  Speaker 2: they're explaining what we currently see, but also predicting what
• 30:14
  Speaker 2: we will find in the future if their model is
• 30:17
  Speaker 2: correct and if their model is not correct, so the
• 30:20
  Speaker 2: testable hypotheses, and that's really important because that shit how
• 30:24
  Speaker 2: we do our future science, what we look for. So
• 30:27
  Speaker 2: I find it really exciting. I'm, you know, really keen
• 30:30
  Speaker 2: to see what happens with the various situations on Planet
• 30:34
  Speaker 2: nine over the coming decades, and if it dies down,
• 30:37
  Speaker 2: I'm sure that in twenty or thirty years, when we
• 30:39
  Speaker 2: get the next generation of next generation of next generation
• 30:42
  Speaker 2: of telescopes, the idea might come up again because we're
• 30:45
  Speaker 2: looking at this ever growing circle of knowledge around the
• 30:48
  Speaker 2: Solar System. But it's not that big yet.
• 30:51
  Speaker 1: The five minutes you just spend on that could have
• 30:53
  Speaker 1: been entered with them. Maybe with them, maybe.
• 30:56
  Speaker 2: But I think it's important to clarify that the this
• 31:00
  Speaker 2: is good science because it does sometimes get passed off
• 31:02
  Speaker 2: as a bit of a joke because there's a past
• 31:04
  Speaker 2: history of things falling flat and those things that fell
• 31:07
  Speaker 2: flat were also a very good science. It's just this
• 31:10
  Speaker 2: is the where science gets done, and it runs counter
• 31:13
  Speaker 2: to the opinion that a lot of people get when
• 31:16
  Speaker 2: they come out of school because of the challenges of
• 31:18
  Speaker 2: the curriculum that science has fact and is science sealed
• 31:21
  Speaker 2: and delivered. And it's one of the problems we've seen
• 31:23
  Speaker 2: with accepting that cigarettes cause contract, accepting that climate change
• 31:27
  Speaker 2: is an issue, is that people get taught that science
• 31:31
  Speaker 2: is signed and sealed and delivered, and then when things change,
• 31:34
  Speaker 2: like Pluto is demoted, that feels like a betrayal. It
• 31:37
  Speaker 2: feels like you've been lighter that somehow things nefarious are
• 31:42
  Speaker 2: going on, and it makes it much harder than to
• 31:46
  Speaker 2: get changes in our understanding through and so it's really
• 31:49
  Speaker 2: important to stress that this is how science works, and
• 31:51
  Speaker 2: this is really good science. No fair point, great point,
• 31:55
  Speaker 2: very good, very good. Jence.
• 31:58
  Speaker 1: That's where we're going to have to finish up. Thank
• 32:00
  Speaker 1: you so very much, Professor Fred Watson, and enjoy your
• 32:04
  Speaker 1: travels and we will catch up with you round late February.
• 32:08
  Speaker 4: Bottle look of it grows like it yep, Thank you, Andrew,
• 32:11
  Speaker 4: thank you, John Ty, and I look forward to listening
• 32:14
  Speaker 4: to Space Nuts podcast without being on it.
• 32:18
  Speaker 2: That will be rare. Yeah, that's just plenty of photo us. Okay, yes,
• 32:22
  Speaker 2: please do.
• 32:24
  Speaker 1: And Professor Johnny Horner, thank you for being a part
• 32:27
  Speaker 1: of Space Nuts Q and A today as well. We'll
• 32:29
  Speaker 1: catch you on the next episode.
• 32:31
  Speaker 2: It's a pleasure. Thank you for having me.
• 32:33
  Speaker 1: And thanks to Hue in the studio who couldn't really
• 32:36
  Speaker 1: do much because he was caught in the ultimate lagrange point.
• 32:39
  Speaker 2: And from me Andrew Dunkley.
• 32:40
  Speaker 1: Oh, don't forget to send us your questions via our
• 32:42
  Speaker 1: website Spacenuts podcast dot com, space Nuts dot io. Get
• 32:46
  Speaker 1: your questions in and we'll get to them as soon
• 32:48
  Speaker 1: as we possibly can.
• 32:50
  Speaker 2: So from me Andrew Dunkley, thanks to your company.
• 32:51
  Speaker 1: See you again on the next episode.
• 32:53
  Speaker 2: Of Space Nuts. Bye bye to the Space Nuts podcast.
• 33:00
  Speaker 2: Available at Apple Podcasts, Spotify, iHeartRadio, or your favorite podcast player.
• 33:06
  Speaker 1: You can also stream on demand at bites dot com.
• 33:10
  Speaker 4: This has been another quality podcast production from nights dot com.