Archived Insights: Europa Clipper, Gravitational Waves, and Black Hole Mysteries
In this special episode of Space Nuts, hosts Andrew Dunkley and Professor Fred Watson take a fascinating journey through some of the most compelling questions and discoveries in astronomy. As they explore the Europa Clipper mission, the nature of gravitational waves, and the enigmatic world of black holes, listeners are treated to a rich tapestry of cosmic knowledge. This episode originally aired in 2019.
Episode Highlights:
- Europa Clipper Mission: Andrew and Fred discuss NASA's exciting approval for the Europa Clipper mission, aimed at exploring Jupiter's icy moon Europa. They delve into the spacecraft's objectives, including investigating the moon's potential subsurface ocean and the challenges posed by Jupiter's intense radiation.
- Gravitational Waves Explained: The hosts explore the recent detection of gravitational waves, speculating on their origins, including a possible black hole-neutron star merger. They discuss the significance of these findings and the ongoing efforts of astronomers to understand the universe's most violent events.
- Black Hole Chris: Listener questions about the nature of black holes spark a lively discussion on topics such as infinite density, event horizons, and the complexities of capturing images of these cosmic phenomena. Andrew and Fred clarify misconceptions and provide insightful explanations.
- Space Travel and Relativity: The episode wraps up with an intriguing listener question about the effects of traveling near the speed of light. Andrew and Fred clarify how relativistic mass works and dispel myths surrounding the transformation of spaceships into black holes.
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00:00:00 --> 00:00:02 Andrew Dunkley: Hi, Andrew Dunkley here. Fred and I are
00:00:02 --> 00:00:04 taking a little bit of a break over the
00:00:04 --> 00:00:06 Christmas New Year period just to catch our
00:00:06 --> 00:00:09 breath. We'll be back, uh, sometime around
00:00:09 --> 00:00:11 mid January. In the meantime, we've been
00:00:11 --> 00:00:14 digging through the archives at some of the
00:00:14 --> 00:00:16 most perplexing and popular
00:00:16 --> 00:00:19 episodes that we've done in recent times. So
00:00:19 --> 00:00:22 sit back and enjoy. 15
00:00:22 --> 00:00:24 seconds. Guidance is internal.
00:00:24 --> 00:00:27 Professor Fred Watson: 10, 9. Ignition
00:00:27 --> 00:00:29 sequence start. Space nets.
00:00:29 --> 00:00:30 Andrew Dunkley: 5, 4, 3.
00:00:30 --> 00:00:33 Professor Fred Watson: 2. 1, 2, 3, 4, 5, 5, 4, 3,
00:00:33 --> 00:00:34 2, 1.
00:00:34 --> 00:00:37 Andrew Dunkley: Space nuts astronauts report it feels
00:00:37 --> 00:00:40 good. Hi there and thanks for joining us on
00:00:40 --> 00:00:42 the Space Nuts podcast. My name's Andrew
00:00:42 --> 00:00:45 Dunkley, your host. And joining me, uh, as
00:00:45 --> 00:00:48 always, Professor Fred Watson, Astronomer at
00:00:48 --> 00:00:51 Large from the department of Da da da da da
00:00:51 --> 00:00:53 da da. It's a pretty long title. That's what
00:00:53 --> 00:00:55 we'll call it from now on. G', day, Fred.
00:00:55 --> 00:00:57 Professor Fred Watson: You could call me the Aaliyah.
00:00:58 --> 00:00:58 Andrew Dunkley: Aal.
00:00:58 --> 00:01:01 Professor Fred Watson: Yeah, when I was Astronomer in Charge, I was
00:01:01 --> 00:01:04 aic. Um, the only trouble is
00:01:04 --> 00:01:06 AAL actually has another significant
00:01:06 --> 00:01:09 meaning in Australian astronomy because it
00:01:09 --> 00:01:10 doesn't only stand for Astronomer at Large,
00:01:10 --> 00:01:13 it also stands for Astronomy Australia
00:01:13 --> 00:01:16 Limited. So, uh, just throw that idea out.
00:01:16 --> 00:01:17 That's a rubbish idea. I'll just be
00:01:17 --> 00:01:18 astronomer.
00:01:18 --> 00:01:21 Andrew Dunkley: Yeah, I was once given the title urrs.
00:01:21 --> 00:01:23 But anyway, um,
00:01:25 --> 00:01:27 some people will understand that.
00:01:27 --> 00:01:29 Professor Fred Watson: Yeah, you've got lovely friends, haven't you?
00:01:29 --> 00:01:30 Andrew Dunkley: I've got a lot of good friends, yes.
00:01:31 --> 00:01:34 Now today we're going to talk about some very
00:01:34 --> 00:01:36 exciting things. It looks like black holes
00:01:36 --> 00:01:38 are still in people's minds. So we're going
00:01:38 --> 00:01:40 to be talking about, um, a couple of
00:01:40 --> 00:01:42 questions that have come in from people about
00:01:42 --> 00:01:45 infinite density. Uh, density. I
00:01:45 --> 00:01:47 keep getting it mixed up with destiny. I
00:01:47 --> 00:01:49 don't know why. Might have been a Back to the
00:01:49 --> 00:01:51 Future movie that confused me on that front.
00:01:51 --> 00:01:54 Uh, uh, and issues, uh, photographing a black
00:01:54 --> 00:01:56 hole. Why were they issues at all? And uh,
00:01:56 --> 00:01:59 another question about space travel and uh,
00:01:59 --> 00:02:02 near light speed travel. Uh, we're also
00:02:02 --> 00:02:04 going to, uh, look at,
00:02:04 --> 00:02:07 um, the cause of a gravitational
00:02:07 --> 00:02:09 wave that was detected recently. This is
00:02:09 --> 00:02:10 exciting because they think they've
00:02:10 --> 00:02:13 pinpointed, uh, an actual cause.
00:02:13 --> 00:02:15 And we're going to start off today.
00:02:15 --> 00:02:17 Professor Fred Watson: Fred, by talking about, uh, this rather.
00:02:17 --> 00:02:19 Andrew Dunkley: Exciting mission that's one step closer to
00:02:19 --> 00:02:22 happening. A mission to Jupiter's ice
00:02:22 --> 00:02:25 moon Europa. And that's what we'll start
00:02:25 --> 00:02:27 with. This, uh, well, this afternoon, this
00:02:27 --> 00:02:29 morning, tonight, this evening, yesterday.
00:02:30 --> 00:02:33 Professor Fred Watson: Whenever. Whenever it is. Yeah, it's,
00:02:33 --> 00:02:36 yeah. So look, a terrific story. Very good
00:02:36 --> 00:02:38 news from uh, NASA that they,
00:02:39 --> 00:02:42 um, the powers that be within NASA have uh,
00:02:42 --> 00:02:45 given the go ahead um, for a
00:02:45 --> 00:02:47 mission called Europa Clipper, which is, is
00:02:47 --> 00:02:49 one of the uh, missions that's been
00:02:50 --> 00:02:53 uh, postulated or sorry proposed is a better
00:02:53 --> 00:02:56 word for um, exploring the moons of the outer
00:02:56 --> 00:02:58 planets. There are a number that are kind of
00:02:58 --> 00:03:00 on the, on the table at the moment, some
00:03:00 --> 00:03:02 further advanced than others. But Europa
00:03:02 --> 00:03:05 Clipper is pretty well advanced and
00:03:05 --> 00:03:08 as you can tell its target, its main target
00:03:08 --> 00:03:11 is Jupiter's moon Europa, which is one of
00:03:11 --> 00:03:14 these um, ocean moons. Ice, uh,
00:03:14 --> 00:03:17 ocean moons. Uh, we believe it has
00:03:17 --> 00:03:19 a covering of ice and we don't know whether
00:03:19 --> 00:03:21 it's thin ice or thick ice. So that would be
00:03:21 --> 00:03:23 one of the things that Europa Clipper would
00:03:23 --> 00:03:26 find out. Um, and an ocean underneath it
00:03:26 --> 00:03:29 and a rocky core. Uh, so
00:03:29 --> 00:03:31 Europa Clipper, I think they are
00:03:31 --> 00:03:34 talking about having it ready for launch in
00:03:34 --> 00:03:36 2023 which is
00:03:36 --> 00:03:39 um, you know, fantastic if they can
00:03:39 --> 00:03:42 do that. That's right. Uh, but apparently
00:03:42 --> 00:03:45 um, that's the
00:03:45 --> 00:03:48 baseline commitment as it's called, supports
00:03:48 --> 00:03:50 a launch readiness date by 2025.
00:03:51 --> 00:03:53 Um, it's all being done at ah, the Propulsion
00:03:53 --> 00:03:56 Laboratory in Pasadena. That's where the
00:03:56 --> 00:03:58 spacecraft will be built. So they've got the
00:03:58 --> 00:04:01 go ahead, um, it's
00:04:01 --> 00:04:04 got the next step,
00:04:04 --> 00:04:07 uh, in approval from NASA, which
00:04:07 --> 00:04:10 I think is a pretty solid one. So I
00:04:10 --> 00:04:13 think you and I, back in 2025
00:04:13 --> 00:04:16 we'll be talking a lot about Europa Clipper.
00:04:16 --> 00:04:19 Andrew Dunkley: Maybe what will be the
00:04:19 --> 00:04:21 basis of the mission? Are they just going
00:04:21 --> 00:04:22 there to have a look?
00:04:22 --> 00:04:25 Professor Fred Watson: Because it is a bit like uh, but it's
00:04:25 --> 00:04:27 a very good look. Um, so it's not going to
00:04:27 --> 00:04:30 land on Europa. It is a proposal to go into
00:04:30 --> 00:04:32 orbit around Europe, actually to go into
00:04:32 --> 00:04:35 orbit around Jupiter. Uh and of course
00:04:35 --> 00:04:37 orbiting Jupiter is always hazardous because
00:04:37 --> 00:04:40 of um, the
00:04:40 --> 00:04:43 intense uh, radiation belts that Jupiter
00:04:43 --> 00:04:45 has. It's got a magnetic field thousands of
00:04:45 --> 00:04:47 times bigger than the Earth and has these
00:04:47 --> 00:04:50 high energy radiation belts around it that
00:04:50 --> 00:04:53 threaten to melt the innards of spacecraft.
00:04:53 --> 00:04:56 Uh, so like the uh, Juno mission which
00:04:56 --> 00:04:58 is currently in orbit around Jupiter, this
00:04:59 --> 00:05:01 uh, Europa Clipper will go into a very
00:05:02 --> 00:05:05 elongated uh, orbit, um, which
00:05:05 --> 00:05:08 will uh, give it 45
00:05:08 --> 00:05:11 flybys of Europa. Uh and
00:05:11 --> 00:05:13 their altitudes will vary from
00:05:13 --> 00:05:16 2700km to 25km.
00:05:16 --> 00:05:17 So it will really be skimming over the
00:05:17 --> 00:05:20 surface. Oh well, and it's got this huge
00:05:20 --> 00:05:23 science package with all the kind of,
00:05:23 --> 00:05:24 you know, the gubbins that you would expect
00:05:24 --> 00:05:27 to find on board something like that,
00:05:28 --> 00:05:31 a mass spectrometer, uh, which
00:05:31 --> 00:05:34 basically measures, you know the weights
00:05:34 --> 00:05:37 of atoms, as you might guess. Uh,
00:05:37 --> 00:05:39 it, um, that is interesting because
00:05:40 --> 00:05:43 Europa, like Saturn's moon Enceladus,
00:05:43 --> 00:05:44 is thought to have, although it hasn't really
00:05:44 --> 00:05:46 been properly confirmed, but thought to have
00:05:47 --> 00:05:50 ice, uh, fountains coming out of
00:05:50 --> 00:05:52 it, um, which are water that's
00:05:52 --> 00:05:55 squirting up through its, uh, through its icy
00:05:55 --> 00:05:57 shell and instantly freezing. It's not
00:05:57 --> 00:06:00 frozen. But if you fly through it, as
00:06:00 --> 00:06:02 Cassini did with Enceladus, then you can
00:06:02 --> 00:06:05 sample what the atomic makeup is. And so
00:06:05 --> 00:06:08 the mass spectrometer will help with that.
00:06:08 --> 00:06:11 Uh, and also, um, it's got this ground
00:06:11 --> 00:06:14 penetrating radar and that's going to be
00:06:14 --> 00:06:17 crucial in characterizing
00:06:17 --> 00:06:19 Europa's crust, um, and
00:06:19 --> 00:06:21 revealing how much of, you know, the
00:06:22 --> 00:06:25 potential water within is oceanic, as
00:06:25 --> 00:06:27 is expected, uh, or whether it is just
00:06:27 --> 00:06:30 pockets of water as we find in Antarctica
00:06:30 --> 00:06:32 and indeed around the South Pole of Mars.
00:06:32 --> 00:06:34 Andrew Dunkley: Will they be able to tell what kind of water
00:06:34 --> 00:06:35 it is?
00:06:36 --> 00:06:38 Professor Fred Watson: Um, uh, to some
00:06:38 --> 00:06:41 extent they will. Um, it may
00:06:41 --> 00:06:44 require a bit of, you know,
00:06:44 --> 00:06:46 inference from other measurements, but if
00:06:46 --> 00:06:49 you've got, uh, samples of ice crystals,
00:06:49 --> 00:06:52 uh, then you can do exactly that. You can,
00:06:52 --> 00:06:55 you know, you can uh, basically
00:06:56 --> 00:06:58 tell whether it's saline water or fresh water
00:06:59 --> 00:07:01 because you can see the, you can measure the
00:07:01 --> 00:07:02 salt content of it.
00:07:02 --> 00:07:02 Andrew Dunkley: It.
00:07:02 --> 00:07:05 Professor Fred Watson: So like um, Saturn's moon
00:07:05 --> 00:07:08 Enceladus, uh, which is actually quite
00:07:08 --> 00:07:10 rich in minerals and it's the silicates in
00:07:10 --> 00:07:12 that that tells you that this water was once
00:07:12 --> 00:07:15 in contact with rock. Uh, I think
00:07:15 --> 00:07:18 the Europa Clipper will be able to sample
00:07:18 --> 00:07:20 exactly those things too. Assuming these
00:07:20 --> 00:07:23 plumes are real, because they're not
00:07:23 --> 00:07:25 well observed. There is evidence. I've seen
00:07:25 --> 00:07:28 images that seem to show these plumes
00:07:28 --> 00:07:31 coming from Europa. Uh, assuming they're real
00:07:31 --> 00:07:33 when they fly through, um, hopefully we will
00:07:33 --> 00:07:35 be able to tell what kind of water it is.
00:07:35 --> 00:07:35 Exactly.
00:07:35 --> 00:07:38 Andrew Dunkley: And will they be able to tell how much
00:07:38 --> 00:07:40 water there is underneath the surface?
00:07:40 --> 00:07:43 Professor Fred Watson: Yes they will because that will very
00:07:43 --> 00:07:46 much be revealed by the um, the ground
00:07:46 --> 00:07:48 penetrating radar in exactly the way
00:07:48 --> 00:07:51 that, um, um, one of the spacecraft in orbit
00:07:51 --> 00:07:53 around Mars, I think it was the, I think it
00:07:53 --> 00:07:55 was, might even have been Mars Reconnaissance
00:07:55 --> 00:07:57 Orbiter, I'm not sure, detected this
00:07:57 --> 00:08:00 lake of liquid water underneath the ice cap
00:08:00 --> 00:08:03 of the southern ice cap of Mars about a year
00:08:03 --> 00:08:06 ago you and I spoke about it. Um, and
00:08:06 --> 00:08:08 they can tell exactly how much there is there
00:08:08 --> 00:08:11 because you can see the boundary with this
00:08:11 --> 00:08:12 sort of radar. You can see the boundary
00:08:12 --> 00:08:14 between an ice surface and a water surface.
00:08:14 --> 00:08:17 And that's crucial to doing this so.
00:08:17 --> 00:08:20 Andrew Dunkley: This mission won't actually be looking
00:08:20 --> 00:08:22 for life, but it will be looking
00:08:23 --> 00:08:25 for, uh, the potential for life
00:08:25 --> 00:08:28 to perhaps exist on a moon
00:08:28 --> 00:08:29 like this.
00:08:30 --> 00:08:33 Professor Fred Watson: Exactly. So as the blurb,
00:08:33 --> 00:08:36 um, on the NASA website says, uh, it
00:08:36 --> 00:08:38 will help scientists investigate the chemical
00:08:38 --> 00:08:40 makeup of Europa's potentially habitable
00:08:40 --> 00:08:43 environment while minimizing the need to
00:08:43 --> 00:08:45 drill through layers of ice so that what
00:08:45 --> 00:08:47 they're going to try and do is as much as
00:08:47 --> 00:08:50 they can from orbit. Um, and
00:08:50 --> 00:08:52 then if there's like, if they find
00:08:52 --> 00:08:55 lipids and amino acids and all this sort of
00:08:55 --> 00:08:57 thing, uh, in the plumes of ice coming,
00:08:58 --> 00:09:00 coming from Europa, then clearly the next
00:09:00 --> 00:09:02 step will be a lander, uh, that starts
00:09:02 --> 00:09:03 digging holes in the ice.
00:09:03 --> 00:09:04 Andrew Dunkley: Yes.
00:09:04 --> 00:09:06 Professor Fred Watson: I mean, you know, before you do that, the
00:09:06 --> 00:09:08 first thing you need to know is how thick the
00:09:08 --> 00:09:09 ice is. Yes.
00:09:09 --> 00:09:11 Andrew Dunkley: If it's a couple of miles thick.
00:09:12 --> 00:09:15 Professor Fred Watson: Well, actually, a couple of miles
00:09:15 --> 00:09:17 is better than what they're expecting.
00:09:17 --> 00:09:17 Andrew Dunkley: Oh, is that right?
00:09:18 --> 00:09:20 Professor Fred Watson: More like 25 or 30 miles
00:09:20 --> 00:09:23 or kilometers. M. That's right. Choose your
00:09:23 --> 00:09:26 units. Um, yes. So, yes,
00:09:26 --> 00:09:28 a thinner layer of ice will be
00:09:29 --> 00:09:31 pretty, pretty, um, good to, you know, to
00:09:31 --> 00:09:33 cope with. You could probably do that. I mean
00:09:33 --> 00:09:35 by thin, I mean less than a kilometer,
00:09:35 --> 00:09:36 probably. Yes.
00:09:36 --> 00:09:39 Andrew Dunkley: But the likelihood, uh, is it's, it's
00:09:39 --> 00:09:40 probably more, but I guess we'll, we'll have
00:09:40 --> 00:09:41 to wait and see.
00:09:43 --> 00:09:45 Professor Fred Watson: Um, Europa's covered in all these cracks that
00:09:45 --> 00:09:46 are, that are brownish in color.
00:09:46 --> 00:09:47 Andrew Dunkley: Yes.
00:09:47 --> 00:09:49 Professor Fred Watson: That's thought to be the effect of sunlight
00:09:49 --> 00:09:52 on brine, on basically on salt water. So
00:09:52 --> 00:09:55 you've already got a hint there that, uh,
00:09:55 --> 00:09:57 it's probably a salty ocean underneath the
00:09:57 --> 00:09:58 surface.
00:09:58 --> 00:10:00 Andrew Dunkley: Well, salt's probably not that uncommon in
00:10:00 --> 00:10:01 the universe really.
00:10:01 --> 00:10:03 Professor Fred Watson: Um, that's right. It's not.
00:10:03 --> 00:10:06 Andrew Dunkley: It's one of, one of the base materials, isn't
00:10:06 --> 00:10:08 it? Uh, of course, this doesn't guarantee
00:10:08 --> 00:10:10 they're actually going to go. This is just
00:10:10 --> 00:10:12 another step forward in the approval process.
00:10:12 --> 00:10:14 Professor Fred Watson: It does, it does.
00:10:14 --> 00:10:16 Andrew Dunkley: Very longitudinal process and they have to
00:10:17 --> 00:10:18 get over a lot of hurdles before they
00:10:18 --> 00:10:21 actually hit the launch button. So, uh,
00:10:21 --> 00:10:23 hopefully they're, um, they're going to get
00:10:23 --> 00:10:26 there and um, it's. It's a long trip too.
00:10:26 --> 00:10:27 Professor Fred Watson: Yes, it is. That's the other thing.
00:10:27 --> 00:10:29 Andrew Dunkley: So they've got to time it right. They've got
00:10:29 --> 00:10:30 to get in the right place at the right time.
00:10:30 --> 00:10:33 Professor Fred Watson: Exactly. All of the above. That's right. So,
00:10:34 --> 00:10:36 uh, at least what it, you know, at least, uh,
00:10:36 --> 00:10:38 it's not a knockback. That's the good news.
00:10:39 --> 00:10:40 Andrew Dunkley: Indeed. All right, well, we'll keep an eye on
00:10:40 --> 00:10:42 this story because I'm sure there'll be more
00:10:42 --> 00:10:45 to report in the not too distant future about
00:10:45 --> 00:10:48 uh, a mission to Europa. You're listening
00:10:48 --> 00:10:51 to Space Nuts with Andrew Dunkley and Fred
00:10:51 --> 00:10:51 Watson.
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00:12:48 --> 00:12:49 Professor Fred Watson: Space Nuts.
00:12:49 --> 00:12:51 Andrew Dunkley: Now Fred, we've uh, discussed
00:12:51 --> 00:12:54 uh, gravitational waves before and
00:12:54 --> 00:12:56 uh, a few of those have been detected in
00:12:56 --> 00:12:59 recent times. The problem with them
00:12:59 --> 00:13:01 is what is the cause?
00:13:02 --> 00:13:05 And now in a recently detected
00:13:05 --> 00:13:08 gravitational wave they think they've got a
00:13:08 --> 00:13:08 candidate.
00:13:09 --> 00:13:11 Professor Fred Watson: That's, that's right. This is so this is, you
00:13:11 --> 00:13:14 know, it's a, an ongoing story. Uh,
00:13:14 --> 00:13:16 what I like about this story is it's got a
00:13:16 --> 00:13:18 nice Australian component because there is
00:13:18 --> 00:13:21 um, there's a, basically
00:13:21 --> 00:13:24 a collaboration here in Australia which is
00:13:24 --> 00:13:26 called osgrav, uh, which is about
00:13:26 --> 00:13:29 gravitational waves. It's a kind of fairly
00:13:29 --> 00:13:31 predictable name but um, it includes people
00:13:31 --> 00:13:34 from the Australian National University and
00:13:34 --> 00:13:36 I think University of Western Australia Other
00:13:36 --> 00:13:38 places which are strong in gravitational wave
00:13:38 --> 00:13:41 astronomy. So, um, it's very nice
00:13:41 --> 00:13:43 that it's. It has this Australian component.
00:13:43 --> 00:13:46 So what's the story? Well, uh, the large.
00:13:47 --> 00:13:49 Sorry, uh, the Laser Interferometer
00:13:49 --> 00:13:51 Gravitational Wave Observatory, Otherwise
00:13:51 --> 00:13:54 known as LIGO, um, has been operating
00:13:55 --> 00:13:57 since, uh, 2015 in its
00:13:58 --> 00:14:00 sort of current state. It's actually
00:14:00 --> 00:14:02 technically called Advanced LIGO because I
00:14:02 --> 00:14:05 think it took 15 years of development to get
00:14:05 --> 00:14:08 to this stage. But they have,
00:14:08 --> 00:14:11 uh, now, not quite regularly, but at, uh,
00:14:11 --> 00:14:13 fairly infrequent intervals. Sorry,
00:14:13 --> 00:14:16 fairly moderately moderate intervals.
00:14:16 --> 00:14:18 Let me put it that way. They've been
00:14:18 --> 00:14:21 detecting gravitational wave events. And for
00:14:21 --> 00:14:22 the last couple of years they've had an
00:14:22 --> 00:14:24 additional string to their bow. Remember,
00:14:24 --> 00:14:26 there are two of these detectors at opposite
00:14:26 --> 00:14:28 corners of the United States,
00:14:28 --> 00:14:31 um, which, um, you need because,
00:14:31 --> 00:14:34 uh, otherwise you've got no idea where these
00:14:34 --> 00:14:36 things come from or even if they're real. You
00:14:36 --> 00:14:38 need to see the gravitational wave pass one
00:14:38 --> 00:14:40 and then the other with the right kind of
00:14:40 --> 00:14:43 time interval in between. Um, but they've
00:14:43 --> 00:14:44 been joined in the last few years by
00:14:44 --> 00:14:47 something called, uh, uh, Virgo, which,
00:14:47 --> 00:14:49 uh. In fact, I think it's called Advanced
00:14:49 --> 00:14:51 Virgo. Like Advanced ligo. Virgo is an
00:14:51 --> 00:14:54 Italian gravitational wave detector. And of
00:14:54 --> 00:14:57 course, having three detectors widely spread
00:14:57 --> 00:14:59 over the surface of the Earth, uh, means you
00:14:59 --> 00:15:01 can pinpoint things much more accurately in
00:15:01 --> 00:15:03 terms of the direction in which these
00:15:03 --> 00:15:04 gravitational waves come in.
00:15:04 --> 00:15:06 Andrew Dunkley: From triangulating the signal.
00:15:07 --> 00:15:09 Professor Fred Watson: Exactly. That's exactly what it is.
00:15:09 --> 00:15:12 Um, what's interesting about this one though,
00:15:12 --> 00:15:15 is that the signal seems to be
00:15:15 --> 00:15:18 from a black hole absorbing
00:15:18 --> 00:15:19 a neutron star.
00:15:21 --> 00:15:24 Um, we actually had a false alarm on
00:15:24 --> 00:15:27 this, which is embarrassing because, um, my
00:15:27 --> 00:15:29 book has just gone to the printer saying,
00:15:29 --> 00:15:31 yes, we've observed a neutron star being
00:15:31 --> 00:15:34 absorbed by a black hole. Um, and
00:15:34 --> 00:15:36 that I think disappeared because it turned
00:15:36 --> 00:15:39 out to be, um, terrestrial noise. It was
00:15:39 --> 00:15:41 sort of, you know. So I don't know whether it
00:15:41 --> 00:15:44 was a train going underneath oven probably,
00:15:44 --> 00:15:46 or. Yeah, something like that. That's the
00:15:46 --> 00:15:48 usual story, isn't it? A microwave oven. Um,
00:15:48 --> 00:15:51 that was earlier this year. And that,
00:15:51 --> 00:15:54 um, has now gone away. But it looks as
00:15:54 --> 00:15:57 though this one might actually be the
00:15:57 --> 00:15:59 real thing. A black hole and a neutron star.
00:16:00 --> 00:16:02 We've had two black holes merging. Uh,
00:16:03 --> 00:16:06 that's probably been the commonest source of,
00:16:06 --> 00:16:07 uh, gravitational waves. There've been
00:16:07 --> 00:16:09 several of those. We've had a couple of
00:16:09 --> 00:16:12 neutron stars merging as well. And that
00:16:12 --> 00:16:14 actually comes with celestial fireworks that
00:16:14 --> 00:16:17 you can observe with other types of
00:16:17 --> 00:16:19 telescope like neutrino telescopes, visible
00:16:19 --> 00:16:22 light telescopes, radio Telescopes, X ray
00:16:22 --> 00:16:25 telescopes, all of the above. Um, and
00:16:25 --> 00:16:27 that was a big story actually late last year
00:16:27 --> 00:16:30 if I remember rightly. But, um, until
00:16:30 --> 00:16:32 now we haven't had a confirmed,
00:16:33 --> 00:16:36 um, observation of a neutron star
00:16:36 --> 00:16:38 being absorbed by a black hole. And we still
00:16:38 --> 00:16:41 don't have. It's still a bit speculative,
00:16:41 --> 00:16:44 but from the masses that are inferred by the
00:16:44 --> 00:16:45 signal. And remember what you get is this
00:16:45 --> 00:16:48 weird gravitational chirp, uh,
00:16:48 --> 00:16:51 it's uh, the frequency of a sound wave
00:16:51 --> 00:16:54 going as the two things come
00:16:54 --> 00:16:56 together. Um, and it's that. That gives you
00:16:56 --> 00:16:58 all the details of what it is that that are
00:16:58 --> 00:17:01 colliding. The suspicion is it's two
00:17:01 --> 00:17:04 objects, one of which is three solar
00:17:04 --> 00:17:06 masses and the other is five
00:17:07 --> 00:17:10 solar masses. I think I'm right in saying
00:17:10 --> 00:17:12 that I should uh, check those numbers. But
00:17:12 --> 00:17:15 anyway, uh, that is the current
00:17:16 --> 00:17:18 expectation, uh, of what is colliding. So
00:17:19 --> 00:17:21 something three solar masses would have to
00:17:21 --> 00:17:24 be a neutron star because it's two
00:17:24 --> 00:17:27 lightweight uh, to be a black hole.
00:17:27 --> 00:17:30 And so, uh, that is what's making this
00:17:30 --> 00:17:32 interesting. What's
00:17:32 --> 00:17:35 perhaps, um, a bit surprising,
00:17:35 --> 00:17:38 uh, is that
00:17:38 --> 00:17:40 you might expect there to be once again
00:17:41 --> 00:17:43 radiation, uh, coming from this, not just
00:17:43 --> 00:17:46 gravitational radiation, but uh, noise
00:17:46 --> 00:17:49 in the X ray spectrum or uh,
00:17:49 --> 00:17:51 neutrinos, uh, particles, things of that
00:17:51 --> 00:17:54 sort, but it hasn't been
00:17:54 --> 00:17:57 observed. And um,
00:17:57 --> 00:17:59 one of the Australian astronomers, uh,
00:18:00 --> 00:18:02 uh, I've forgotten her first name. That's
00:18:02 --> 00:18:04 embarrassing, isn't it? Susan. Susan Scott.
00:18:04 --> 00:18:07 Uh, she's at um, anu Australian
00:18:07 --> 00:18:10 National University. Uh, she says that
00:18:10 --> 00:18:13 uh, if she said. Well
00:18:13 --> 00:18:15 what she says is we've looked for light
00:18:15 --> 00:18:16 signatures of the event, but no one has found
00:18:16 --> 00:18:19 any up to this point. That indicates that if
00:18:19 --> 00:18:22 it is a black hole and a neutron star, then
00:18:22 --> 00:18:24 very likely the neutron star has been
00:18:24 --> 00:18:27 swallowed whole by, by the black hole. Uh,
00:18:27 --> 00:18:29 uh, he said, and she says this could happen
00:18:29 --> 00:18:32 if the objects were of different masses.
00:18:32 --> 00:18:35 So it's. The smaller object gets sucked in
00:18:35 --> 00:18:37 more quickly and, and is swallowed whole. So
00:18:37 --> 00:18:40 you know, it's not strung out into, into this
00:18:41 --> 00:18:44 um, mess of material that does emit
00:18:44 --> 00:18:46 um, uh, signals in the
00:18:46 --> 00:18:49 electromagnetic uh, wave bands. Uh,
00:18:49 --> 00:18:52 if it gets sucked in hole, maybe you don't
00:18:52 --> 00:18:53 get any signal at all except for the
00:18:53 --> 00:18:55 gravitational wave signal.
00:18:55 --> 00:18:56 Andrew Dunkley: It's extraordinary how sudd
00:18:58 --> 00:19:01 impact be. I mean, you know, neutron
00:19:01 --> 00:19:03 stars, we've talked about them and they're
00:19:03 --> 00:19:05 pretty volatile individuals and
00:19:06 --> 00:19:08 quite dense, um,
00:19:08 --> 00:19:09 quite dense.
00:19:09 --> 00:19:11 Professor Fred Watson: It's just a slight understatement there.
00:19:12 --> 00:19:13 Yes, indeed.
00:19:13 --> 00:19:16 Andrew Dunkley: Um, so I imagine
00:19:16 --> 00:19:19 it'd be quite a cataclysmic collision.
00:19:19 --> 00:19:22 Professor Fred Watson: Yeah, that's right. Um, in fact, so
00:19:22 --> 00:19:25 when you've got two black holes, um, what you
00:19:25 --> 00:19:27 get at the end of it is a more massive black
00:19:27 --> 00:19:30 hole. Uh, and, um, you're
00:19:30 --> 00:19:32 talking there though about, you
00:19:32 --> 00:19:35 know, infinitely small, infinitesimally small
00:19:35 --> 00:19:38 points merging, uh, their event horizon.
00:19:38 --> 00:19:41 There are two event horizons merge as well,
00:19:41 --> 00:19:42 and you get something called the ring down
00:19:42 --> 00:19:45 where the event horizon itself vibrates.
00:19:45 --> 00:19:48 Um, I think with a neutron star you wouldn't
00:19:48 --> 00:19:51 have the event horizon, but it will be
00:19:51 --> 00:19:53 possible for the neutron star just basically
00:19:53 --> 00:19:55 to disappear. Over the black holes event
00:19:55 --> 00:19:57 horizon, you don't see anything. But, uh,
00:19:57 --> 00:19:59 neutron stars themselves, as you and I have
00:19:59 --> 00:20:01 talked about many times, are active in the
00:20:01 --> 00:20:02 sense that they've got highly intense
00:20:02 --> 00:20:05 magnetic fields on their surfaces and they
00:20:05 --> 00:20:07 beam this radiation out, which we see as
00:20:08 --> 00:20:11 pulsars. So they're not particularly
00:20:11 --> 00:20:13 quiet things. I mean, this thing could be a
00:20:13 --> 00:20:16 pulsar whose lighthouse beam of
00:20:16 --> 00:20:19 radiation is missing the Earth, if I can put
00:20:19 --> 00:20:21 it that way. Because the only reason we see
00:20:21 --> 00:20:23 pulsars is when you've got a neutron star
00:20:23 --> 00:20:26 whose, uh, beams of radiation from their
00:20:26 --> 00:20:28 poles actually sweeps across the Earth. And
00:20:28 --> 00:20:30 that of course, is a particular, uh,
00:20:30 --> 00:20:33 circumstance. Maybe this one wasn't like
00:20:33 --> 00:20:36 that and it's just got chewed up, uh, and
00:20:37 --> 00:20:40 we haven't seen its demise other than in
00:20:40 --> 00:20:41 the gravitational waves.
00:20:41 --> 00:20:43 I think there'll be more about this story,
00:20:43 --> 00:20:45 Andrew, and, um, I hope you and I can bring
00:20:45 --> 00:20:48 it to our, uh, Space Nuts
00:20:48 --> 00:20:50 listeners or listeners, our fraternity.
00:20:52 --> 00:20:54 Andrew Dunkley: Yes, uh, well, um,
00:20:55 --> 00:20:58 the more we can gather in terms of data,
00:20:58 --> 00:21:01 uh, on gravitational waves, the more we
00:21:01 --> 00:21:04 will learn and who knows what
00:21:04 --> 00:21:05 sort of problems it could solve down the
00:21:05 --> 00:21:06 track, so.
00:21:06 --> 00:21:09 Professor Fred Watson: Exactly. It's always my comment that you
00:21:09 --> 00:21:12 never know what you're setting in store for
00:21:12 --> 00:21:13 the future from all this knowledge.
00:21:13 --> 00:21:14 Andrew Dunkley: Exactly.
00:21:14 --> 00:21:14 Professor Fred Watson: Yeah.
00:21:14 --> 00:21:16 Andrew Dunkley: I, uh, mean, you just, just gather the
00:21:16 --> 00:21:18 knowledge. One day it might just go, you, ah,
00:21:18 --> 00:21:20 know, a penny will drop with someone else,
00:21:20 --> 00:21:23 maybe a generation down the track, who knows?
00:21:23 --> 00:21:25 It's all useful. And even if it's not, it's
00:21:25 --> 00:21:28 good to be able to gather it and they
00:21:28 --> 00:21:29 use it. Some, some.
00:21:29 --> 00:21:32 Professor Fred Watson: That's right. It's um, you know, all these
00:21:32 --> 00:21:34 things are constantly testing Einstein's
00:21:34 --> 00:21:36 theory of relativity. And that's
00:21:38 --> 00:21:39 very, um, important because we know there's
00:21:39 --> 00:21:41 something wrong with it, but we haven't found
00:21:41 --> 00:21:43 anything wrong with it yet. Even though it's
00:21:43 --> 00:21:45 been tested within an inch of its life, it's
00:21:45 --> 00:21:46 still holds up.
00:21:46 --> 00:21:48 Andrew Dunkley: Yeah, fascinating.
00:21:48 --> 00:21:51 All right, you're listening to the Space Nuts
00:21:51 --> 00:21:54 podcast With Andrew Dunkley and Fred Watson.
00:21:56 --> 00:21:58 Professor Fred Watson: Okay, we checked all four systems and being
00:21:58 --> 00:22:00 with a girl, Space Nuts.
00:22:00 --> 00:22:02 Andrew Dunkley: Now Fred, I do want to shout out once again
00:22:02 --> 00:22:05 to our patrons, um, that number
00:22:05 --> 00:22:08 39 now thank uh, you so
00:22:08 --> 00:22:10 much for supporting the Space Nuts podcast.
00:22:10 --> 00:22:13 We so appreciate it. And if you're interested
00:22:13 --> 00:22:14 in becoming a patron, you can, can do
00:22:14 --> 00:22:17 so@patreon.com spacenuts
00:22:17 --> 00:22:19 that's patreon.com
00:22:20 --> 00:22:23 spacenuts and um, thank you to
00:22:23 --> 00:22:25 everybody who has joined the Space Nuts
00:22:25 --> 00:22:28 podcast group. They number in their hundreds.
00:22:28 --> 00:22:31 Now Fred, we've only had the page going for
00:22:31 --> 00:22:33 a bit over a week and uh, already we've
00:22:33 --> 00:22:35 tracked the century and
00:22:36 --> 00:22:39 have over 100 people that are all Space Nuts
00:22:39 --> 00:22:41 fans who are all now talking to each other
00:22:41 --> 00:22:43 and uh, answering each other's questions and,
00:22:43 --> 00:22:46 and uh, having a fair bit of fun. So I'm
00:22:46 --> 00:22:49 so pleased we were able to put um, those
00:22:49 --> 00:22:51 people together and who uh, knows friends,
00:22:51 --> 00:22:54 friendships may be forged. Uh, that's
00:22:54 --> 00:22:56 great. Or collaborations that might solve
00:22:56 --> 00:22:58 some of the mysteries of the universe. Who
00:22:58 --> 00:23:01 knows, uh, that would be a lovely legacy I
00:23:01 --> 00:23:03 think. Uh, let's um, and of course if
00:23:03 --> 00:23:06 you would like to be a member uh, of the
00:23:06 --> 00:23:09 Space Nuts podcast group, um, just find it,
00:23:09 --> 00:23:11 it, it's on Facebook, uh, Space Nuts podcast
00:23:11 --> 00:23:14 group in your search engine and um, yes, just
00:23:14 --> 00:23:17 ask to join and we will click the approve
00:23:17 --> 00:23:19 button. Everybody seems to be like minded and
00:23:19 --> 00:23:21 enjoying themselves. So uh, that's what it's
00:23:21 --> 00:23:22 all about.
00:23:23 --> 00:23:26 Now Fred, some questions if you
00:23:26 --> 00:23:29 will. Um, hello again fellow nutters.
00:23:29 --> 00:23:31 I have a question I'm hoping you can help me.
00:23:31 --> 00:23:33 Um, understanding an old
00:23:33 --> 00:23:36 chestnut black holes. If a black hole is
00:23:36 --> 00:23:39 an infinite dense point, why does it have a
00:23:39 --> 00:23:42 diameter? I don't why astronomers refer
00:23:42 --> 00:23:44 to black holes by their size in terms of
00:23:44 --> 00:23:46 diameter. When it's meant to be a point of
00:23:46 --> 00:23:48 infinite density, are they
00:23:48 --> 00:23:51 mistakenly referring to the event horizon?
00:23:51 --> 00:23:54 Mario from Melbourne. Hello Mario. Thanks for
00:23:54 --> 00:23:54 the question.
00:23:55 --> 00:23:57 Professor Fred Watson: And the answer is yes, thank you Mario.
00:23:57 --> 00:23:58 Andrew Dunkley: Thanks for the question.
00:23:59 --> 00:24:02 Professor Fred Watson: Um, Mario then goes on to uh, you
00:24:02 --> 00:24:05 know, everything he says is absolutely right,
00:24:05 --> 00:24:07 that um, uh, if you've got a, a
00:24:07 --> 00:24:10 point of infinite density, it's got zero
00:24:10 --> 00:24:12 dimensions, so you can't refer to its
00:24:12 --> 00:24:15 diameter. Uh, what you can refer to is
00:24:15 --> 00:24:18 its mass because the mass is uh,
00:24:19 --> 00:24:21 variable. Uh, but the fact that
00:24:21 --> 00:24:24 it has no volume means that when you, you
00:24:24 --> 00:24:26 know, when you look at the mass per unit
00:24:26 --> 00:24:27 volume, you've got something of infinite
00:24:27 --> 00:24:30 density, which is how density is defined.
00:24:30 --> 00:24:33 So Mario is absolutely right. Uh, what
00:24:33 --> 00:24:36 does vary though? With the maps is the event
00:24:36 --> 00:24:38 horizon, the diameter of the event horizon,
00:24:38 --> 00:24:40 which you and I have spoken before. Um,
00:24:41 --> 00:24:44 uh, uh, it's a
00:24:44 --> 00:24:47 quantity that I suppose is
00:24:47 --> 00:24:49 important because if we are observing,
00:24:50 --> 00:24:52 um, a black hole, as we did with the Event
00:24:52 --> 00:24:54 Horizon telescope, then that's what you see.
00:24:55 --> 00:24:56 Uh, so a big one is going to be easier to
00:24:56 --> 00:24:58 observe than a smaller one. And that's why a
00:24:58 --> 00:25:00 supermassive black hole, uh, in the center of
00:25:00 --> 00:25:03 a galaxy called M M87 was chosen for the
00:25:03 --> 00:25:05 first target for that Event Horizon
00:25:05 --> 00:25:07 Telescope. But no, Mario, you're quite right.
00:25:07 --> 00:25:10 Um, it is that, uh, astronomers, when,
00:25:10 --> 00:25:12 if they talk about the diameter of a black
00:25:12 --> 00:25:14 hole, and that probably includes me as well,
00:25:14 --> 00:25:16 uh, are actually really referring to the
00:25:16 --> 00:25:19 event horizon because that's the parameter.
00:25:19 --> 00:25:22 And I love the way Mario signs off by saying
00:25:22 --> 00:25:25 thanks in advance to Dave and Fred. Uh,
00:25:25 --> 00:25:27 although he does say, AKA Andrew.
00:25:27 --> 00:25:29 Andrew Dunkley: Yes, that one's going to stick for a while,
00:25:30 --> 00:25:33 sorry to say. Thank you, Mario.
00:25:35 --> 00:25:37 Moving on. Uh, hi, Andrew and Fred. It's
00:25:37 --> 00:25:39 Andrew from Newcastle with another question,
00:25:39 --> 00:25:42 if I may. Just watched a doco on the quest
00:25:42 --> 00:25:44 to capture the first photograph of a black
00:25:44 --> 00:25:47 hole, uh, rather accurately, the shadow of a
00:25:47 --> 00:25:49 black hole, as Fred so eloquently explained.
00:25:49 --> 00:25:52 And I didn't understand one thing.
00:25:52 --> 00:25:54 Amongst others, of course, with the multiple
00:25:54 --> 00:25:56 observatories around the world and the use of
00:25:56 --> 00:25:58 atomic clocks to synchronize the data
00:25:58 --> 00:26:01 acquisition, why were they, uh, on
00:26:01 --> 00:26:04 tenterhooks, uh, regarding the weather
00:26:04 --> 00:26:06 at all the sites, with, uh, bad weather at
00:26:06 --> 00:26:09 just one, putting the whole venture in peril.
00:26:09 --> 00:26:11 I understand from the show and other sources
00:26:11 --> 00:26:13 that they were collecting radio wavelength
00:26:13 --> 00:26:16 data. And I thought that this was unaffected
00:26:16 --> 00:26:18 by the weather and atmospheric conditions. I
00:26:18 --> 00:26:21 thought that, uh, was the intrinsic beauty of
00:26:21 --> 00:26:23 radio astronomy. Day and night, rain and
00:26:23 --> 00:26:26 shine. Hope you can enlighten me.
00:26:26 --> 00:26:29 Wait for it. But over the radio. Dear,
00:26:29 --> 00:26:31 oh, dear. Uh, Andrew Broadhurst. Thank you,
00:26:31 --> 00:26:31 Andrew.
00:26:32 --> 00:26:33 Professor Fred Watson: That's a great question. Andrew.
00:26:33 --> 00:26:35 Andrew Dunkley: Leave the jokes to me, man.
00:26:37 --> 00:26:39 Professor Fred Watson: Yeah, well, I always leave them to you. So.
00:26:41 --> 00:26:42 Andrew Dunkley: Um, some to live. They're good.
00:26:43 --> 00:26:46 Professor Fred Watson: Oh, gosh. When was the last. Oh, never mind.
00:26:48 --> 00:26:49 Uh, Andrew's on the money. There is, you
00:26:49 --> 00:26:52 know, I thought radio waves were unaffected
00:26:52 --> 00:26:54 by the weather. And the answer is that radio
00:26:54 --> 00:26:56 waves come in different flavors. Uh, and
00:26:56 --> 00:26:59 so, uh, what you might call low frequency
00:26:59 --> 00:27:01 radio waves, um, which are still
00:27:01 --> 00:27:04 relatively, you know, they're way outside the
00:27:04 --> 00:27:06 medium wave band of radio and things of that
00:27:06 --> 00:27:09 sort. But low frequency in radio astronomy,
00:27:09 --> 00:27:12 um, I guess goes up to a couple of gigahertz
00:27:12 --> 00:27:15 or something like that. Um, those
00:27:15 --> 00:27:17 are largely unaffected by weather. That's
00:27:17 --> 00:27:19 absolutely right. So that's why it can be
00:27:19 --> 00:27:22 pouring down at Parkes, the radio dish there.
00:27:22 --> 00:27:24 And the astronomers are still happily
00:27:24 --> 00:27:26 observing through that. But the Event Horizon
00:27:26 --> 00:27:29 Telescope used higher frequencies. Uh, in
00:27:29 --> 00:27:32 fact, one of the telescopes that was
00:27:32 --> 00:27:34 incorporated into it was alma. The Atacama
00:27:34 --> 00:27:37 Large Millimeter Array, which has featured
00:27:37 --> 00:27:40 very, uh, very widely on space knots. That is
00:27:40 --> 00:27:43 a high frequency, uh, radio
00:27:43 --> 00:27:46 array. In fact, they have
00:27:46 --> 00:27:48 receivers that go up to, uh, more than
00:27:48 --> 00:27:51 900 gigahertz. So that's like, you know,
00:27:51 --> 00:27:53 nearly a thousand times higher frequencies
00:27:53 --> 00:27:56 than what we've just been talking about. And
00:27:56 --> 00:27:58 those sorts of frequencies, uh, the weather
00:27:59 --> 00:28:01 plays a very important role. Because water
00:28:01 --> 00:28:04 vapor actually dramatically
00:28:04 --> 00:28:06 absorbs the microwave signals.
00:28:07 --> 00:28:09 Andrew Dunkley: And that's what experience that watching
00:28:09 --> 00:28:11 satellite television. If there is a storm
00:28:11 --> 00:28:14 and it rains heavily, the wavelengths of the
00:28:14 --> 00:28:17 raindrops can absorb the signals from the
00:28:17 --> 00:28:18 satellite and you get nothing.
00:28:19 --> 00:28:21 Professor Fred Watson: Uh, that's interesting. I've never tried to
00:28:21 --> 00:28:24 watch satellite television. So that's, that's
00:28:24 --> 00:28:25 good thing to know.
00:28:25 --> 00:28:27 Andrew Dunkley: Um, it's one of the pitfalls.
00:28:27 --> 00:28:30 Professor Fred Watson: Yes, yes. In fact, I seldom watch television
00:28:30 --> 00:28:32 at all. So that's probably why. Um,
00:28:33 --> 00:28:35 but the bottom line is, um, you know, it's
00:28:35 --> 00:28:38 why facilities like ALMA and some
00:28:38 --> 00:28:41 of the other radio telescopes that were used,
00:28:41 --> 00:28:44 uh, to become the Event
00:28:44 --> 00:28:46 Horizon Telescopes, why they're all at high
00:28:46 --> 00:28:48 altitudes. Alma is at almost
00:28:48 --> 00:28:51 5 meters above sea level. Level,
00:28:51 --> 00:28:54 um, that's, you know, 15, 16ft.
00:28:54 --> 00:28:57 And at that height, there is very little
00:28:57 --> 00:28:59 water vapor in the atmosphere. Uh, but you
00:28:59 --> 00:29:01 can still get weather. And that's why they
00:29:01 --> 00:29:03 were indeed on tenterhooks about the weather.
00:29:03 --> 00:29:06 Because they don't want any of these, uh, if
00:29:06 --> 00:29:09 you lose one of those arrays, and
00:29:09 --> 00:29:10 I think there were eight of them that came
00:29:10 --> 00:29:12 together all around one hemisphere of the
00:29:12 --> 00:29:15 Earth, uh, to make up the Event
00:29:15 --> 00:29:17 Horizon Telescope. If you lose one of them,
00:29:17 --> 00:29:20 them, you lose a significant amount of your
00:29:20 --> 00:29:22 ability to reconstruct the image that they're
00:29:22 --> 00:29:24 seeing. Uh, and so that was why they were
00:29:24 --> 00:29:26 worried that the weather on just one of them
00:29:26 --> 00:29:29 might be, uh, moist, uh, or damper
00:29:29 --> 00:29:31 than they can cope with. And that would have
00:29:31 --> 00:29:33 screwed up the whole thing. But as it
00:29:33 --> 00:29:35 happened, it wasn't. It didn't happen. And it
00:29:35 --> 00:29:36 was great.
00:29:36 --> 00:29:38 Andrew Dunkley: They got global good weather.
00:29:38 --> 00:29:40 Professor Fred Watson: They did global good weather at these high
00:29:40 --> 00:29:41 altitude sites. That's right. The job.
00:29:41 --> 00:29:44 Andrew Dunkley: All right, there you are, Andrew. Uh, thank
00:29:44 --> 00:29:46 you for your question. And we've got one
00:29:46 --> 00:29:49 more. We'll squeeze in from John Sputh. I
00:29:49 --> 00:29:51 hope I pronounced that correctly. John,
00:29:51 --> 00:29:52 thanks for your question.
00:29:52 --> 00:29:52 Professor Fred Watson: Hi.
00:29:52 --> 00:29:54 Andrew Dunkley: I have a question that's been bugging me for
00:29:54 --> 00:29:56 some time and I need an expert to help me
00:29:56 --> 00:29:59 out. I think we should stop there. Fred.
00:30:00 --> 00:30:01 Professor Fred Watson: There's nobody here, is there? Who's that?
00:30:01 --> 00:30:03 Hang on. I'll go and see if I can find
00:30:03 --> 00:30:03 somebody.
00:30:04 --> 00:30:06 Andrew Dunkley: The cat could probably answer this one.
00:30:07 --> 00:30:09 Now, imagine, um, a spaceship traveling close
00:30:09 --> 00:30:12 to the speed of light. Disregarding that we
00:30:12 --> 00:30:13 don't have that sort of propulsion just yet.
00:30:14 --> 00:30:16 Would the increase in its
00:30:16 --> 00:30:19 relativistic mass at some point turn
00:30:19 --> 00:30:22 the spaceship into a black hole? And if so,
00:30:22 --> 00:30:25 would that spell the end of the ship and its
00:30:25 --> 00:30:27 crew? Or would they be able to slow down to
00:30:27 --> 00:30:30 reverse the process? What a great question.
00:30:30 --> 00:30:32 Professor Fred Watson: It is a fantastic question. Do you want to
00:30:32 --> 00:30:33 have a go at it?
00:30:33 --> 00:30:34 Andrew Dunkley: Uh, the answer is no.
00:30:36 --> 00:30:38 Professor Fred Watson: It is. You got right. Yeah, you're right on
00:30:38 --> 00:30:40 the money. They see. See, there is an expert.
00:30:40 --> 00:30:42 It's called Andrew Dunkley or Dave 50.
00:30:42 --> 00:30:43 Andrew Dunkley: 50 chance.
00:30:45 --> 00:30:48 Professor Fred Watson: Um, it's a great question. And it,
00:30:48 --> 00:30:51 it. The answer is a little bit, um,
00:30:51 --> 00:30:53 prosaic, I think. And that is that
00:30:54 --> 00:30:56 in the, in the rest frame of the
00:30:56 --> 00:30:59 spacecraft, you know. So if you're on the
00:30:59 --> 00:31:01 spacecraft and you're going at almost the
00:31:01 --> 00:31:04 speed of light, your mass doesn't change.
00:31:04 --> 00:31:07 It's only in the rest frame of
00:31:07 --> 00:31:10 a stationary observer. And by that I mean
00:31:10 --> 00:31:12 somebody watching you go past, somebody
00:31:12 --> 00:31:15 watches you hurl past. And your mass gets
00:31:15 --> 00:31:17 very much higher to the
00:31:17 --> 00:31:19 observer. But to the,
00:31:20 --> 00:31:23 the inhabitants of the spacecraft or the
00:31:23 --> 00:31:25 spacecraft itself, your mass doesn't change.
00:31:25 --> 00:31:25 Andrew Dunkley: It's.
00:31:25 --> 00:31:27 Professor Fred Watson: You're still normal. It is still normal.
00:31:28 --> 00:31:31 Yeah. And the same story is true with time
00:31:31 --> 00:31:33 dilation. You know that when you go
00:31:33 --> 00:31:36 nearer the speed of light, your clocks tick
00:31:36 --> 00:31:39 slower. Uh, that's a. Seen by a stationary
00:31:39 --> 00:31:42 observer. Uh, and so it's the same sort of
00:31:42 --> 00:31:43 thing. If you're on the spacecraft, your
00:31:43 --> 00:31:45 clock is ticking at the same rate as it ever
00:31:45 --> 00:31:47 was. But to a stationary observer, your
00:31:47 --> 00:31:48 clocks tick slower.
00:31:48 --> 00:31:51 Andrew Dunkley: And this has been proven with atomic clocks,
00:31:51 --> 00:31:51 hasn't it?
00:31:51 --> 00:31:54 Professor Fred Watson: It has. And indeed with mass as well. You can
00:31:54 --> 00:31:56 do this, you can see this sort of phenomenon
00:31:56 --> 00:31:58 with, um, uh. With uh,
00:31:58 --> 00:32:01 cosmic rays which travel very close to the
00:32:01 --> 00:32:02 speed of light. You can see their mass
00:32:02 --> 00:32:05 change. So, um, that's
00:32:05 --> 00:32:07 from the point of view of somebody who's, you
00:32:07 --> 00:32:10 know, not moving at the same speed. If you're
00:32:10 --> 00:32:11 moving at the same speed, you don't see any
00:32:11 --> 00:32:12 change at all.
00:32:13 --> 00:32:16 Andrew Dunkley: That's pretty boring. The more we Discuss
00:32:16 --> 00:32:18 black holes and the number of questions we
00:32:18 --> 00:32:21 get about them. People are really quite
00:32:22 --> 00:32:25 captivated by the strangeness of
00:32:25 --> 00:32:27 them. I suppose they throw up all these
00:32:27 --> 00:32:30 things that seem so alien to what we consider
00:32:30 --> 00:32:32 normal. Uh, and that's because we've only
00:32:32 --> 00:32:35 experienced um, what's happening on our
00:32:35 --> 00:32:38 planet at any given time. So to try
00:32:38 --> 00:32:41 and comprehend um, enough gravity to
00:32:41 --> 00:32:44 warp time to slow things down
00:32:44 --> 00:32:47 to the observer and increase mass. Just,
00:32:47 --> 00:32:49 it's really whack.
00:32:50 --> 00:32:53 Professor Fred Watson: Sad on the brain. That's true. But uh,
00:32:53 --> 00:32:56 look, John's question there is a great
00:32:56 --> 00:32:58 question because it's not intuitively
00:32:58 --> 00:33:01 obvious what is happening uh,
00:33:01 --> 00:33:04 in a situation like something traveling close
00:33:04 --> 00:33:06 to the speed of light. And it, and so he's
00:33:06 --> 00:33:09 right to ask would that mass actually turn it
00:33:09 --> 00:33:11 into a black hole? Uh, but the answer is no
00:33:11 --> 00:33:13 because of the reasons that I've outlined.
00:33:13 --> 00:33:14 But it's great, great thinking.
00:33:14 --> 00:33:16 Andrew Dunkley: It is indeed. Thank you John. Thanks for the
00:33:16 --> 00:33:18 question. Do appreciate it. Keep your
00:33:18 --> 00:33:20 questions coming in. We're trying to um, run
00:33:20 --> 00:33:23 them down but they, it's, it's, it's an ever
00:33:23 --> 00:33:25 growing mass really.
00:33:25 --> 00:33:27 Professor Fred Watson: It's. All right, look, as you said earlier
00:33:27 --> 00:33:30 Andrew, um, all the space nutters are going
00:33:30 --> 00:33:31 to get together and sort them out for
00:33:31 --> 00:33:33 themselves and we'll be, that'll be
00:33:33 --> 00:33:34 encouraged.
00:33:34 --> 00:33:36 Andrew Dunkley: Actually if uh, people want to ask questions
00:33:36 --> 00:33:39 of the group uh, and discuss it,
00:33:39 --> 00:33:42 they. Yeah, by all means. Um, that, that's
00:33:42 --> 00:33:44 part of the reason we set up the Space Nuts
00:33:44 --> 00:33:46 podcast group. So um, it's a good opportunity
00:33:46 --> 00:33:49 to not only meet like minded people who enjoy
00:33:49 --> 00:33:52 these, these topics, but also to maybe come
00:33:52 --> 00:33:54 up with your own ideas on, on what might,
00:33:54 --> 00:33:55 might be and you know, I'll keep an eye on it
00:33:55 --> 00:33:57 and if something pops in there that we think
00:33:57 --> 00:34:00 is worthy of further discussion, we will
00:34:00 --> 00:34:03 certainly investigate that. Thanks
00:34:03 --> 00:34:05 to everyone who um, who sent in their
00:34:05 --> 00:34:08 questions, uh, and uh, contributed and joined
00:34:08 --> 00:34:10 the Space Nuts podcast group and Patreon and
00:34:10 --> 00:34:13 everything else. We really appreciate it. Uh,
00:34:13 --> 00:34:15 but most of all we appreciate you Fred. Thank
00:34:15 --> 00:34:15 you so much.
00:34:16 --> 00:34:18 Professor Fred Watson: It's a pleasure, thank you for having me as
00:34:18 --> 00:34:19 always.
00:34:19 --> 00:34:22 Andrew Dunkley: And we will catch you next week. Professor
00:34:22 --> 00:34:24 Fred Watson, uh, astronomer at large and from
00:34:24 --> 00:34:27 me Andrew Dunkley. Thank you again and we'll
00:34:27 --> 00:34:29 catch you next time on another edition of
00:34:29 --> 00:34:32 SpaceNuts. Uh, you'll be
00:34:32 --> 00:34:34 listening to the Space Nuts podcast
00:34:36 --> 00:34:38 available at Apple Podcasts, Spotify,
00:34:39 --> 00:34:41 iHeartRadio or your favorite podcast
00:34:41 --> 00:34:43 player. You can also stream on
00:34:43 --> 00:34:45 demand@bytes.com.
00:34:45 --> 00:34:47 Professor Fred Watson: This has been another quality podcast
00:34:47 --> 00:34:49 production from bytes.com.