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Cosmic Curiosities: Exploring Planet Nine and Gravitational Waves
In this engaging Q&A episode of Space Nuts, host Heidi Campo and the brilliant Professor Fred Watson answer a variety of listener questions that delve into the mysteries of our universe. From the search for Planet Nine to the nature of black holes and the behavior of gravitational waves, this episode promises to enlighten and entertain.
Episode Highlights:
- The Search for Planet Nine: Jakob from Norway poses a thought-provoking question about the mathematical predictions surrounding Planet Nine and why we can't pinpoint its location with the same accuracy as Neptune's discovery in 1846. Fred explains the differences in observational techniques and the statistical challenges faced by astronomers today.
- Understanding Black Holes: Young listener Enrique asks how black holes can have density if their singularity lacks volume. Fred breaks down the concept of density and how it relates to the mass of black holes, providing a clear explanation for this complex topic.
- Target of Opportunity Observations: Ben from Northwestern University inquires about how observatories handle interruptions in their schedules for significant astronomical events. Fred discusses the common practice of prioritizing observations of transient phenomena like supernovae and gravitational waves, shedding light on the intricacies of telescope time management.
- Gravitational Waves Explained: Fenton from Minnesota asks about the nature of gravitational waves and their potential interactions. Fred clarifies how these waves behave similarly to light waves, including their ability to interfere and the variety of frequencies they encompass, making for a fascinating discussion.
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Stay curious, keep looking up, and join us next time for more stellar insights and cosmic wonders. Until then, clear skies and happy stargazing.
(00:00) Welcome to Space Nuts with Heidi Campo and Fred Watson
(01:20) Discussion on the search for Planet Nine
(15:00) Exploring the nature of black holes
(25:30) Target of opportunity observations at observatories
(35:00) Understanding gravitational waves and their interactions
For commercial-free versions of Space Nuts, join us on Patreon, Supercast, Apple Podcasts, or become a supporter here: https://www.spreaker.com/podcast/space-nuts-astronomy-insights-cosmic-discoveries--2631155/support
00:00:00 --> 00:00:02 Heidi Campo: Welcome back to another fun, exciting
00:00:03 --> 00:00:06 Q and A episode of space
00:00:06 --> 00:00:06 nuts.
00:00:07 --> 00:00:09 Generic: 15 seconds. Guidance is internal.
00:00:09 --> 00:00:12 10, 9. Ignition
00:00:12 --> 00:00:15 sequence start. Space nuts. 5, 4, 3,
00:00:15 --> 00:00:18 2. 1. 2, 3, 4, 5, 5, 4,
00:00:18 --> 00:00:21 3, 2, 1. Space nuts. Astronauts
00:00:21 --> 00:00:22 report it feels good.
00:00:23 --> 00:00:25 Heidi Campo: I am your substitute host for this episode,
00:00:25 --> 00:00:28 Heidi Campo. And joining us is professor
00:00:28 --> 00:00:30 Fred Watson, astronomer at large.
00:00:31 --> 00:00:32 How are you doing today, Fred?
00:00:32 --> 00:00:35 Professor Fred Watson: Um, I'm very well, thanks, Heidi, and great
00:00:35 --> 00:00:37 to see you, as always. And I hope you're well
00:00:37 --> 00:00:39 and I hope you're surviving the thunderstorm
00:00:39 --> 00:00:40 that apparently is going on around you at the
00:00:40 --> 00:00:41 moment.
00:00:41 --> 00:00:43 Heidi Campo: It is. You know, like I just said,
00:00:44 --> 00:00:46 would I would rather have a thunderstorm than
00:00:46 --> 00:00:48 a hurricane? Because I am here in Space
00:00:48 --> 00:00:50 Center Houston, not m. Space Center, Space
00:00:50 --> 00:00:53 City. I'm not in the Space Center. I'm in
00:00:53 --> 00:00:56 Space City. Um, we did have a hurricane last
00:00:56 --> 00:00:58 year that was not fun. Um,
00:00:59 --> 00:01:01 I was alone. My husband was traveling at the
00:01:01 --> 00:01:03 time for work, and I had a broken foot. My
00:01:03 --> 00:01:06 neighbor's tree. The trunk didn't
00:01:06 --> 00:01:09 fall, but almost all of the big branches did.
00:01:09 --> 00:01:11 So I was out there with a broken foot
00:01:11 --> 00:01:14 brace on my leg crutches and a chainsaw
00:01:14 --> 00:01:17 trying to chop up these branches and deal
00:01:17 --> 00:01:20 with it. Dealing with my first hurricane.
00:01:20 --> 00:01:23 And then we didn't have power for nine days.
00:01:23 --> 00:01:26 It was awful. In the middle of July. Oh,
00:01:26 --> 00:01:26 whoa, whoa.
00:01:27 --> 00:01:27 Professor Fred Watson: That's awful.
00:01:28 --> 00:01:31 Heidi Campo: So those are. I guess
00:01:31 --> 00:01:34 I just. Just sheer will, I
00:01:34 --> 00:01:37 guess. But those of you who live, um,
00:01:37 --> 00:01:39 in climates where you don't get hurricanes,
00:01:40 --> 00:01:40 enjoy those.
00:01:41 --> 00:01:43 M. Speaking of,
00:01:44 --> 00:01:46 looks like our first question today is from
00:01:48 --> 00:01:51 Jakob or Jacob. If I'm saying that right,
00:01:51 --> 00:01:53 I think it's Jakob from Norway.
00:01:54 --> 00:01:56 Uh, they do not get any hurricanes there. You
00:01:56 --> 00:01:58 are safe from hurricanes, and you get to
00:01:58 --> 00:02:01 enjoy the auroras. Jakob's, uh, question
00:02:01 --> 00:02:04 is, um. Hi, this is Jakob
00:02:04 --> 00:02:06 from Norway. I'm working on a presentation
00:02:06 --> 00:02:09 about planet nine for my school, where I will
00:02:09 --> 00:02:12 be comparing the mathematical prediction of
00:02:12 --> 00:02:14 the nine planet with
00:02:14 --> 00:02:17 Urbian. Lee Verriners.
00:02:17 --> 00:02:20 You'll have to correct me on that, Fred. Um,
00:02:20 --> 00:02:23 work to finding Neptune. In
00:02:23 --> 00:02:25 1864, Lee Varenner saw
00:02:25 --> 00:02:28 that something was wrong with the orbit of
00:02:28 --> 00:02:30 Uranus and figured out that it was getting
00:02:32 --> 00:02:34 pulled on by another planet. He told
00:02:34 --> 00:02:37 astronomers exactly where to look for this
00:02:37 --> 00:02:39 planet. And surely enough, they found Neptune
00:02:39 --> 00:02:41 on the first night of looking. What are the
00:02:41 --> 00:02:44 odds of that? Now, almost 200 years later,
00:02:44 --> 00:02:46 scientists see something wrong with some
00:02:46 --> 00:02:48 objects in the Jupiter belt and say that,
00:02:49 --> 00:02:51 excuse me, say that another planet may be
00:02:51 --> 00:02:53 causing these strange orbital paths. My
00:02:53 --> 00:02:56 question is, why can't we predict
00:02:56 --> 00:02:59 exactly where Planet Nine is like Lee
00:02:59 --> 00:03:02 Varenner did in 1864. Have we gotten
00:03:02 --> 00:03:05 worse at maths? Thank you for the great
00:03:05 --> 00:03:07 podcast and.
00:03:07 --> 00:03:08 Professor Fred Watson: Thank you for the great question Jakob
00:03:09 --> 00:03:11 because um, you know you've hit the nail on
00:03:11 --> 00:03:14 the head there. You're quite right about uh,
00:03:14 --> 00:03:16 the discovery of Neptune. Um
00:03:17 --> 00:03:19 um it's usually said that Neptune was the
00:03:19 --> 00:03:22 first planet discovered with the point of
00:03:22 --> 00:03:25 a pen because it was calculations by
00:03:25 --> 00:03:27 Le Verrier and also um,
00:03:28 --> 00:03:31 actually a British ah, astronomer,
00:03:32 --> 00:03:33 uh, I think his name was Adams, I might be
00:03:33 --> 00:03:35 misremembering that uh, who did the
00:03:35 --> 00:03:38 calculations at the same time and also
00:03:38 --> 00:03:40 predicted the existence of another planet.
00:03:40 --> 00:03:42 But he couldn't get anybody in England
00:03:42 --> 00:03:45 interested in actually following up on it. Le
00:03:45 --> 00:03:48 Verrier um, basically was
00:03:48 --> 00:03:50 fortunate in having the director of the
00:03:50 --> 00:03:52 Berlin Observatory um,
00:03:52 --> 00:03:55 uh, to help him out. And that was
00:03:55 --> 00:03:57 when Neptune was discovered exactly where it
00:03:57 --> 00:04:00 was predicted. Now Planet nine, uh,
00:04:00 --> 00:04:03 you're absolutely right. There's a nice
00:04:03 --> 00:04:06 link there between um, 1846
00:04:06 --> 00:04:08 and the early 2000s because it was back in
00:04:08 --> 00:04:11 2016 that two American astronomers
00:04:12 --> 00:04:14 figured out that there was something about
00:04:14 --> 00:04:17 the orbits of uh, objects
00:04:17 --> 00:04:20 as you mentioned in the Kuiper Belt, uh,
00:04:20 --> 00:04:22 which are uh, aligned in a way that
00:04:22 --> 00:04:25 suggested that there's another planet out
00:04:25 --> 00:04:28 there, uh, that's pulling them all into
00:04:28 --> 00:04:31 uh, this alignment, this orbital alignment,
00:04:31 --> 00:04:34 um, but we haven't found it yet and
00:04:34 --> 00:04:36 some suggest that, that it doesn't exist at
00:04:36 --> 00:04:38 all. And the difference between
00:04:39 --> 00:04:42 the discovery of Neptune and the search for
00:04:42 --> 00:04:45 Planet nine is that Neptune, uh
00:04:45 --> 00:04:47 the prediction of Neptune's existence was
00:04:47 --> 00:04:50 based on very accurate observations
00:04:50 --> 00:04:53 of one object which was the planet Uranus
00:04:53 --> 00:04:55 uh in the outer solar system. And it was what
00:04:55 --> 00:04:58 we call perturbations in the orbit of Uranus,
00:04:59 --> 00:05:01 Uh but that means it's being pulled out
00:05:01 --> 00:05:04 of what you'd normally expect
00:05:04 --> 00:05:07 to see. And it's that pulling that was
00:05:07 --> 00:05:09 attributed Neptune. And you can then because
00:05:09 --> 00:05:11 you're only looking at well three objects,
00:05:11 --> 00:05:14 the Sun, Uranus and the other, whatever
00:05:14 --> 00:05:16 mystery body it is which turned out to be
00:05:16 --> 00:05:18 Uranus. You can do the calculation and
00:05:18 --> 00:05:21 predict pretty exactly where you're going to
00:05:21 --> 00:05:23 find the as ah, yet unknown object. And
00:05:23 --> 00:05:26 that's what happened. It's a great story uh,
00:05:26 --> 00:05:28 with lots of twists and turns. It's a bit
00:05:28 --> 00:05:31 different with Planet nine. What we're seeing
00:05:31 --> 00:05:33 is uh, the suggestion uh, that some
00:05:33 --> 00:05:36 of the orbits of these Kuiper Belt objects
00:05:36 --> 00:05:39 are aligned in a way that uh, means that
00:05:39 --> 00:05:41 they're being pulled uh, out of a uh,
00:05:42 --> 00:05:44 different orbit by a hidden planet. But
00:05:44 --> 00:05:47 you're now talking about not accurate
00:05:47 --> 00:05:49 positions of gravitational pulls. You're
00:05:49 --> 00:05:52 talking about statistical, uh, uh,
00:05:52 --> 00:05:54 discussions because you're talking about many
00:05:54 --> 00:05:57 objects, uh, and you're talking about many
00:05:57 --> 00:06:00 orbits. And one of the reasons
00:06:00 --> 00:06:03 why, uh, this is such a difficult problem
00:06:03 --> 00:06:06 is that if there was an object pulling
00:06:06 --> 00:06:09 these, uh, Kuiper Belt objects into their
00:06:09 --> 00:06:11 elongated orbits, into their aligned orbits,
00:06:12 --> 00:06:14 uh, it would be a very long way away from the
00:06:14 --> 00:06:16 sun. It would be very faint and very
00:06:16 --> 00:06:19 difficult to see. But the other thing is
00:06:19 --> 00:06:21 you can't be sure that you're not
00:06:21 --> 00:06:24 seeing a statistical fluke. And a
00:06:24 --> 00:06:27 number of scientists have pointed this out
00:06:27 --> 00:06:29 that maybe the Kuiper Belt objects, these
00:06:29 --> 00:06:32 icy asteroids beyond the orbit of Neptune,
00:06:32 --> 00:06:35 uh, those objects are uh, just a small
00:06:35 --> 00:06:38 sound of what is a bigger
00:06:38 --> 00:06:40 sample that we have not yet discovered. And
00:06:40 --> 00:06:42 if we could see the whole sample, there
00:06:42 --> 00:06:44 wouldn't be an issue. There would be no
00:06:44 --> 00:06:46 preferred alignment. Uh, so it's what we
00:06:46 --> 00:06:48 would call a selection effect. It's a
00:06:48 --> 00:06:51 statistical fluke. So that's the bottom
00:06:51 --> 00:06:54 line with this. It's a statistical business
00:06:54 --> 00:06:57 rather than a, ah, direct gravitational
00:06:57 --> 00:07:00 um, calculation which is what it was for
00:07:00 --> 00:07:02 Neptune. So we haven't yet found planet nine.
00:07:02 --> 00:07:05 A lot of people are still looking. I'm kind
00:07:05 --> 00:07:07 of hopeful that we will do. But the latest
00:07:07 --> 00:07:09 results suggests that maybe it's not there at
00:07:09 --> 00:07:09 all.
00:07:11 --> 00:07:13 Heidi Campo: Sounds like, um, machine learning may be
00:07:13 --> 00:07:16 a very beneficial asset in
00:07:16 --> 00:07:18 discovering these statistics and
00:07:18 --> 00:07:21 advanced, advanced formulas to find this.
00:07:22 --> 00:07:24 Professor Fred Watson: That's right. I'm sure people are throwing
00:07:24 --> 00:07:27 AI at uh, this problem. Uh,
00:07:27 --> 00:07:29 there's only so much you can do though
00:07:29 --> 00:07:32 because you're limited with the data
00:07:32 --> 00:07:34 set that you've got to start with, which is
00:07:34 --> 00:07:35 something like, I don't know, I think they're
00:07:35 --> 00:07:38 about 10 of these, uh, asteroids which
00:07:38 --> 00:07:40 are particularly aligned that suggest the
00:07:40 --> 00:07:42 existence of planet nine.
00:07:42 --> 00:07:44 Heidi Campo: This is true. This is true.
00:07:45 --> 00:07:48 Well, our next question is from
00:07:48 --> 00:07:50 Enrique and this is an audio question that we
00:07:50 --> 00:07:51 will play for you now.
00:07:52 --> 00:07:55 Henrique: Hello, I'm, um, Henrique from
00:07:55 --> 00:07:57 Portugal. Thank you for
00:07:58 --> 00:08:01 answering my last question about space
00:08:01 --> 00:08:04 time. I have another one.
00:08:04 --> 00:08:07 How do black holes have density
00:08:08 --> 00:08:11 if the singularity doesn't have
00:08:11 --> 00:08:13 volume? Thank you.
00:08:14 --> 00:08:14 Bye.
00:08:14 --> 00:08:17 Heidi Campo: It's always so sweet to hear from Enrique.
00:08:17 --> 00:08:20 Um, you said he was, uh, what did we say
00:08:20 --> 00:08:22 his last email said he was six.
00:08:23 --> 00:08:25 So. Is that right, Fred? I think when they
00:08:25 --> 00:08:28 emailed us before he said he was 6 years old.
00:08:28 --> 00:08:29 Professor Fred Watson: Yes, that's correct.
00:08:29 --> 00:08:32 Heidi Campo: Something like that, yeah. No Enrique, so
00:08:32 --> 00:08:35 cute. He's so smart too. I'm like, man,
00:08:35 --> 00:08:37 I was not thinking about this stuff when I
00:08:37 --> 00:08:37 was his age.
00:08:38 --> 00:08:40 Professor Fred Watson: Yeah, me neither. Sorry.
00:08:41 --> 00:08:44 Um, uh, just to let our listeners
00:08:44 --> 00:08:46 know that we are improvising here, we're
00:08:46 --> 00:08:49 listening separately to, uh, it might
00:08:49 --> 00:08:52 be Henrik rather than Enrique. Anyway, it's
00:08:52 --> 00:08:54 um, Henrik by the sound of it, from Portugal.
00:08:55 --> 00:08:58 And I was listening slightly after you, so
00:08:58 --> 00:09:00 I could. So that's why you, you didn't get a
00:09:00 --> 00:09:03 response from me to your question, which I'm
00:09:03 --> 00:09:05 sure Huw will tidy up when he edits this
00:09:06 --> 00:09:08 whole thing. Um, his question was,
00:09:09 --> 00:09:11 um, how can you have.
00:09:12 --> 00:09:14 How can an object have density when it's got
00:09:14 --> 00:09:17 zero volume? I, uh, think I'm
00:09:17 --> 00:09:19 paraphrasing that correctly. And, uh,
00:09:19 --> 00:09:22 Henrik has gone straight to
00:09:22 --> 00:09:25 the nub of the matter with a black hole
00:09:25 --> 00:09:27 because a black hole is effectively
00:09:27 --> 00:09:30 defined as a point in space which has
00:09:30 --> 00:09:33 infinite density. Uh, now
00:09:33 --> 00:09:36 black holes have mass and we can measure
00:09:36 --> 00:09:37 different masses for black holes. Some are
00:09:37 --> 00:09:40 supermassive black holes, uh, which have
00:09:40 --> 00:09:42 masses millions or even billions of times the
00:09:42 --> 00:09:45 mass of the sun. Uh, some are stellar, uh,
00:09:46 --> 00:09:48 mass black holes, which are similar in mass
00:09:48 --> 00:09:51 to the sun. Uh, but they all have mass.
00:09:52 --> 00:09:54 If they don't have volume, though, uh, you'll
00:09:54 --> 00:09:56 remember. Maybe you don't know this formula,
00:09:56 --> 00:09:59 Henrique. I, uh, don't think I did when I was
00:09:59 --> 00:10:02 6. But density is mass
00:10:02 --> 00:10:04 divided by volum. If volume is zero,
00:10:05 --> 00:10:07 and that's the way we think a black hole is,
00:10:07 --> 00:10:10 then the density is infinite. Uh, because
00:10:10 --> 00:10:12 if you divide something by zero, the answer
00:10:12 --> 00:10:14 you get is infinity. Two very odd
00:10:14 --> 00:10:16 mathematical quirks. So,
00:10:17 --> 00:10:20 um, it's possible that
00:10:20 --> 00:10:23 real black holes don't have infinite density,
00:10:23 --> 00:10:25 but their densities are very, very high
00:10:25 --> 00:10:28 because a black hole by definition is
00:10:28 --> 00:10:31 either zero volume or at least a very,
00:10:31 --> 00:10:33 very small volume. Uh, so it's a great
00:10:33 --> 00:10:36 question and what you is, you've basically
00:10:36 --> 00:10:38 gone to the heart of what defines a black
00:10:38 --> 00:10:39 hole. Well done.
00:10:39 --> 00:10:41 Heidi Campo: And we absolutely need more young people
00:10:41 --> 00:10:44 interested in this stuff. I saw. Um,
00:10:44 --> 00:10:46 I'm actually. Oh, I'm gonna brag for a
00:10:46 --> 00:10:48 second. I am a brand new aunt for the first
00:10:48 --> 00:10:51 time. I had my first nephew. So
00:10:51 --> 00:10:53 shout out to baby Roman. So excited you're
00:10:53 --> 00:10:55 here. But I was looking through baby books
00:10:55 --> 00:10:57 and I guess they have the cutest little baby
00:10:57 --> 00:10:59 books these days. You can get quantum, um,
00:10:59 --> 00:11:02 physics for babies, astronomy, um, for
00:11:02 --> 00:11:05 babies, um, math for
00:11:05 --> 00:11:06 babies. They have all sorts of cute little
00:11:06 --> 00:11:08 book and I am so excited because I'm going to
00:11:08 --> 00:11:10 buy him all the science books in the world
00:11:10 --> 00:11:13 because their brains are little
00:11:13 --> 00:11:16 sponges and they can learn so much so fast.
00:11:16 --> 00:11:17 And I'm like, you know what we should do is
00:11:17 --> 00:11:20 we should have little kids solving these
00:11:20 --> 00:11:22 problems because they would probably come up
00:11:22 --> 00:11:24 with the answer faster than an adult
00:11:24 --> 00:11:28 would.0G.
00:11:28 --> 00:11:29 Professor Fred Watson: And I feel fine.
00:11:29 --> 00:11:32 Heidi Campo: Space Nuts. Well, our uh, next question.
00:11:32 --> 00:11:34 Professor Fred Watson: Congratulations on your um, on being an
00:11:34 --> 00:11:35 aunt.
00:11:35 --> 00:11:38 Heidi Campo: Thank you so much. Oh, I'm so excited. He's
00:11:38 --> 00:11:38 so cute.
00:11:39 --> 00:11:42 Um, our next question is from Ben.
00:11:42 --> 00:11:44 Um, Ben, looks like you're emailing us from
00:11:44 --> 00:11:47 Northwestern University. Ben says
00:11:48 --> 00:11:51 I don't know how common it is, but I do know
00:11:51 --> 00:11:53 for certain. I do know for certain things
00:11:53 --> 00:11:56 like gravitational wave detections, many
00:11:56 --> 00:11:58 observations will drop or uh, many
00:11:58 --> 00:12:01 observatories will drop what they're doing to
00:12:01 --> 00:12:04 attempt to observe the source of the waves.
00:12:04 --> 00:12:06 I have four questions about this.
00:12:07 --> 00:12:09 One, is it common for
00:12:09 --> 00:12:12 observatories to do this? Two,
00:12:12 --> 00:12:15 for what sort of events do
00:12:15 --> 00:12:17 observatories do this? Three,
00:12:17 --> 00:12:20 are there any sort of observations
00:12:21 --> 00:12:23 which are immune to these interruptions?
00:12:23 --> 00:12:26 And four, my understanding is that
00:12:26 --> 00:12:29 observing time is quite constricted, highly
00:12:29 --> 00:12:32 scheduled and difficult to obtain. So
00:12:32 --> 00:12:34 how do they compensate for these
00:12:34 --> 00:12:36 interruptions? Do they just move the entire
00:12:36 --> 00:12:38 schedule schedule back? Do they just find a
00:12:38 --> 00:12:40 different slot for the observations that were
00:12:40 --> 00:12:43 interrupted while keeping most
00:12:43 --> 00:12:46 observations unimpacted or something else?
00:12:46 --> 00:12:49 Professor Fred Watson: Thanks Heidi and Ben. That's um, a question
00:12:49 --> 00:12:51 that I don't think we've ever been asked
00:12:51 --> 00:12:53 before on Space Nuts. And it's a really good
00:12:53 --> 00:12:56 question because it's part and parcel of
00:12:56 --> 00:12:59 the work of your average
00:12:59 --> 00:13:02 observatory. Uh, and so
00:13:02 --> 00:13:03 the first of your four questions, is it
00:13:03 --> 00:13:06 common for observatories to do this? And the
00:13:06 --> 00:13:09 answer is yes. Uh, these are
00:13:10 --> 00:13:11 effectively what we call target of
00:13:11 --> 00:13:13 opportunity observations where
00:13:14 --> 00:13:17 uh, you know the scheduled use of a
00:13:17 --> 00:13:19 telescope. And you're absolutely right, those
00:13:19 --> 00:13:22 schedules are ah, laid down months in
00:13:22 --> 00:13:25 advance. People have applied for
00:13:25 --> 00:13:28 telescope time, sweat, blood and tears
00:13:28 --> 00:13:31 to actually uh, get their applications in and
00:13:31 --> 00:13:33 succeed in winning the telescope time. I used
00:13:33 --> 00:13:35 to do this quite a lot back in the day.
00:13:36 --> 00:13:38 Um, typically uh, on the Anglo Australian
00:13:38 --> 00:13:40 telescope, which is the one I used most, uh,
00:13:40 --> 00:13:43 the biggest visible uh, light telescope in
00:13:43 --> 00:13:45 Australia. Uh, typically for
00:13:45 --> 00:13:48 every night uh, of available observing
00:13:48 --> 00:13:50 time there will be three to four different
00:13:50 --> 00:13:53 groups wanting to use it. So that's the level
00:13:53 --> 00:13:55 of competition that there is. And of course
00:13:55 --> 00:13:58 only one wins out. And the result of that is
00:13:58 --> 00:14:00 you might be allocated two or three nights
00:14:00 --> 00:14:03 and four occasionally got fauna
00:14:03 --> 00:14:06 allocations where you're at the mercy of the
00:14:06 --> 00:14:08 weather, uh, and at the mercy of all the
00:14:08 --> 00:14:09 instruments working but you've worked so hard
00:14:09 --> 00:14:12 to get that time. Uh, the last thing you want
00:14:12 --> 00:14:15 is for somebody to come along and say, oh,
00:14:15 --> 00:14:17 there's been, uh, X, Y or Z happening in
00:14:17 --> 00:14:19 the space. We're going to grab your
00:14:19 --> 00:14:22 telescope. But, um, it is,
00:14:22 --> 00:14:25 uh, sort of built into most observatories
00:14:25 --> 00:14:28 that, that is a potential way of
00:14:28 --> 00:14:31 operating. I guess some don't. Uh,
00:14:31 --> 00:14:32 but certainly at the Anglo Australian
00:14:32 --> 00:14:34 Telescop, uh, these
00:14:35 --> 00:14:38 target of opportunity observations were made.
00:14:39 --> 00:14:41 Um, so, uh, Ben, your second question is for
00:14:41 --> 00:14:43 what sort of events do observatories do this?
00:14:43 --> 00:14:46 Well, as you said, uh, it's, you know,
00:14:46 --> 00:14:49 some of the gravitational wave detections in
00:14:49 --> 00:14:50 recent months of, um,
00:14:52 --> 00:14:54 neutron star collisions where there might be
00:14:55 --> 00:14:58 a radio or optical counterpart, in other
00:14:58 --> 00:15:00 words, a flash either in the radio spectrum
00:15:00 --> 00:15:03 or the visible light spectrum. Uh, then you
00:15:03 --> 00:15:05 would that the target of opportunity
00:15:06 --> 00:15:08 rules would kick in because there would have
00:15:08 --> 00:15:11 to be rules about this. Um, it works, I
00:15:11 --> 00:15:13 think, for radio telescopes as well. I don't
00:15:13 --> 00:15:16 have any direct experience of observing on
00:15:16 --> 00:15:17 radio, um, telescopes, but I do know about
00:15:18 --> 00:15:20 the other kind, the optical telescopes. And
00:15:20 --> 00:15:22 yes, your time will be taken over.
00:15:22 --> 00:15:25 So neutron star collisions, um,
00:15:25 --> 00:15:27 supernovae is the most common one. If you've
00:15:27 --> 00:15:30 got a bright supernova, uh, and you have
00:15:30 --> 00:15:32 a telescope that's got the right equipment on
00:15:32 --> 00:15:35 it, you will probably turn to that to detect,
00:15:35 --> 00:15:38 uh, the supernova explosion and measure its
00:15:38 --> 00:15:40 spectrum at the peak of its intensity. Uh,
00:15:41 --> 00:15:44 that's happened a lot. Gamma ray bursts,
00:15:44 --> 00:15:46 the visible light counterparts of things that
00:15:46 --> 00:15:49 are detected by gamma ray satellites.
00:15:49 --> 00:15:52 That's happened too. Uh, so these things are,
00:15:52 --> 00:15:54 um. You know, there are several transient,
00:15:54 --> 00:15:57 what we call transient phenomena for which
00:15:57 --> 00:15:59 this kind of, um, uh, observation
00:15:59 --> 00:16:01 would be made. Uh, number three, are there
00:16:01 --> 00:16:03 any sorts of observations that are immune to
00:16:03 --> 00:16:05 these interruptions? Well, that be. Would.
00:16:05 --> 00:16:08 Would depend, I think, on the policies of the
00:16:08 --> 00:16:10 particular observatory in question. There
00:16:10 --> 00:16:12 might well be, um, certainly at the aat,
00:16:13 --> 00:16:16 uh, there weren't. We did a lot of
00:16:16 --> 00:16:18 routine survey work where we were building up
00:16:18 --> 00:16:20 large catalogues of information on things.
00:16:20 --> 00:16:23 And that would be very much, uh, something
00:16:23 --> 00:16:26 that could be interrupted by, uh, a target
00:16:26 --> 00:16:29 of opportunity observation. Uh, and four,
00:16:29 --> 00:16:30 my understanding is that observing time is
00:16:30 --> 00:16:32 quite constrained, highly scheduled and
00:16:32 --> 00:16:35 difficult to obtain. Indeed it is. So how do
00:16:35 --> 00:16:38 they compensate for those interruptions? Uh,
00:16:38 --> 00:16:40 do they just move the entire schedule back?
00:16:40 --> 00:16:43 No, they don't. Uh, what they do is
00:16:43 --> 00:16:45 the astronomers who've lost the time
00:16:46 --> 00:16:48 really, uh, have to face the fact that
00:16:48 --> 00:16:51 they've lost the time. Um, and that
00:16:51 --> 00:16:53 might be, you know, one of the conditions
00:16:53 --> 00:16:55 under which they accept the time, the
00:16:55 --> 00:16:57 telescope time in the first place. Um,
00:16:57 --> 00:17:00 often though, there will be,
00:17:00 --> 00:17:03 uh, you know, there will be moves
00:17:03 --> 00:17:06 to try and compensate, uh, for
00:17:06 --> 00:17:09 that loss of time. And that's the
00:17:09 --> 00:17:11 last part of your question. Do they just find
00:17:11 --> 00:17:14 a different slot for the observations that
00:17:14 --> 00:17:15 were interrupted while keeping most
00:17:15 --> 00:17:18 observations unimpacted? That's basically the
00:17:18 --> 00:17:21 way it works. Uh, and in the
00:17:21 --> 00:17:24 case of the Anglo Australian telescope, we
00:17:24 --> 00:17:27 had, uh, time. There was a small amount of
00:17:27 --> 00:17:29 time that was not allocated to users. We
00:17:29 --> 00:17:31 called it director's time because it was at
00:17:31 --> 00:17:34 the director's discretion to allocate that
00:17:34 --> 00:17:36 time, whether it was for hardware
00:17:36 --> 00:17:38 improvements or whatever tests, things of
00:17:38 --> 00:17:41 that sort. Uh, but, um, that is what
00:17:41 --> 00:17:44 normally would happen. The director would try
00:17:44 --> 00:17:46 and allocate some of his director's time
00:17:47 --> 00:17:49 to compensate for somebody who had lost time
00:17:49 --> 00:17:51 because of a target opportunity observation.
00:17:52 --> 00:17:54 The great question. Thanks very much, Ben.
00:17:54 --> 00:17:57 Heidi Campo: Yeah, and I can attest to that. My good
00:17:57 --> 00:17:59 friend, um, Dr. Allison McGraw, she's a
00:17:59 --> 00:18:01 planetary scientist over at the Lunar and
00:18:01 --> 00:18:04 Planetary Institute, and she is always
00:18:04 --> 00:18:07 competing to get the best telescope time. Um,
00:18:07 --> 00:18:09 she was just in Hawaii not too long ago and
00:18:09 --> 00:18:11 she was so excited because it was perfect,
00:18:11 --> 00:18:13 perfect conditions and she got everything she
00:18:13 --> 00:18:14 wanted.
00:18:14 --> 00:18:15 Professor Fred Watson: Very good.
00:18:18 --> 00:18:20 Generic: Three, two, one.
00:18:21 --> 00:18:22 Heidi Campo: Space nuts.
00:18:22 --> 00:18:24 All right, so this brings us to our very last
00:18:24 --> 00:18:27 question for the evening, which is from
00:18:27 --> 00:18:30 Fenton. And this is an audio question that I
00:18:30 --> 00:18:32 will play for you now. I'll
00:18:32 --> 00:18:35 give Fred just a second to get synced up with
00:18:35 --> 00:18:35 me.
00:18:35 --> 00:18:36 Professor Fred Watson: Synced up with me.
00:18:36 --> 00:18:39 Heidi Campo: And then we can, we can both hit play
00:18:39 --> 00:18:41 at the same time and listen to Fenton's
00:18:41 --> 00:18:43 question, which you will hear now.
00:18:43 --> 00:18:46 Fenton: Hey, Fred and Andrew, this is Fenton from St.
00:18:46 --> 00:18:49 Paul, Minnesota, in the U.S. uh,
00:18:49 --> 00:18:51 I understand you guys need some questions, so
00:18:51 --> 00:18:53 here's one for you to think about. I really
00:18:53 --> 00:18:55 like, by the way, uh, everything that you do
00:18:55 --> 00:18:58 with the questions, whether they're good or
00:18:58 --> 00:19:00 bad, you always do a good job of coming up
00:19:00 --> 00:19:03 with something interesting on them. So you
00:19:03 --> 00:19:06 guys talk a lot about gravity waves.
00:19:07 --> 00:19:10 And I ask myself, can you
00:19:10 --> 00:19:13 compare a gravity wave to a
00:19:13 --> 00:19:16 geometrical wave that is a sinusoidal
00:19:16 --> 00:19:18 wave or a sine wave that's going to have
00:19:18 --> 00:19:20 regular minima and maxima
00:19:21 --> 00:19:23 to it? So what do you think of that? Does
00:19:23 --> 00:19:25 that make any sense? Um, and
00:19:25 --> 00:19:28 then if that were the case, I thought,
00:19:29 --> 00:19:31 can two gravity waves interact?
00:19:32 --> 00:19:35 Can they either double their intensity or
00:19:35 --> 00:19:36 nullify each other?
00:19:38 --> 00:19:40 Can they be in phase or out of phase is
00:19:40 --> 00:19:43 another way of looking at it. And then
00:19:43 --> 00:19:45 if we want to continue this classical
00:19:46 --> 00:19:49 analogy of, um, speed
00:19:49 --> 00:19:51 is equal, uh, to
00:19:51 --> 00:19:53 wavelength divided by time.
00:19:54 --> 00:19:57 Can one gravity have a wavelength
00:19:57 --> 00:19:59 that, for example, would be one half
00:20:00 --> 00:20:02 that of the others? In other words, you'd
00:20:02 --> 00:20:04 have a sort of phase shifting there, maybe.
00:20:05 --> 00:20:06 I'd love to hear what you think about it. I
00:20:06 --> 00:20:08 hope you like the question. Cue up the good
00:20:08 --> 00:20:11 job and stay, uh, warm
00:20:11 --> 00:20:13 down there. Bye now.
00:20:13 --> 00:20:16 Heidi Campo: Well, that was a very nice question. Thank
00:20:16 --> 00:20:18 you so much, Fenton. I will stay warm.
00:20:22 --> 00:20:24 It's nothing but warm here in Houston in the
00:20:24 --> 00:20:25 summertime for us.
00:20:25 --> 00:20:27 Professor Fred Watson: Yes, I can imagine. So, Fenton,
00:20:27 --> 00:20:30 that's a, uh, good set of questions. And the
00:20:30 --> 00:20:33 answer to most of your questions in there is
00:20:33 --> 00:20:35 yes, uh, the,
00:20:35 --> 00:20:38 um, gravitational waves, ah, are,
00:20:38 --> 00:20:41 uh, waves. They're basically
00:20:41 --> 00:20:44 vibrations of space. Uh, and you probably
00:20:44 --> 00:20:47 know that, um, the waves
00:20:47 --> 00:20:50 that we're normally familiar with, like sound
00:20:50 --> 00:20:51 waves, are what are called longitudinal
00:20:51 --> 00:20:54 waves. The molecules of
00:20:54 --> 00:20:57 air move backwards and forwards as the wave
00:20:57 --> 00:20:59 progresses. Whereas, uh, light waves
00:21:00 --> 00:21:02 are transverse, uh, waves. Which are
00:21:02 --> 00:21:05 a vibration of the magnetic and
00:21:05 --> 00:21:08 electric fields, uh, which are, uh, you know,
00:21:08 --> 00:21:11 existent at any given time. So, uh, they are.
00:21:12 --> 00:21:14 They are sinusoidal is the way you describe
00:21:14 --> 00:21:16 them. Gravitational waves are something
00:21:16 --> 00:21:19 different. They're called quadrupole waves.
00:21:19 --> 00:21:22 And they're a bit like sine waves,
00:21:22 --> 00:21:24 but they've got a sort of rotational
00:21:24 --> 00:21:26 component to them as well. So
00:21:27 --> 00:21:30 they are not, um, exactly like, uh,
00:21:30 --> 00:21:33 a light wave. But they are similar,
00:21:33 --> 00:21:36 uh, in broad characteristics. And
00:21:36 --> 00:21:39 in particular, they are similar in that,
00:21:39 --> 00:21:41 yes, they can interfere with one another.
00:21:41 --> 00:21:42 That's the phenomenon that you were talking
00:21:42 --> 00:21:45 about, uh, where, uh, light waves
00:21:45 --> 00:21:48 can either cancel out or add. Uh, to
00:21:48 --> 00:21:50 give you these, what we call fringe patterns,
00:21:51 --> 00:21:53 uh, gravitational waves can do that as well.
00:21:53 --> 00:21:55 Uh, the quadrupole waves can interfere with
00:21:55 --> 00:21:58 one another. And you're also right that
00:21:58 --> 00:22:01 they come in different wavelengths. We
00:22:01 --> 00:22:03 normally think of it as different
00:22:03 --> 00:22:05 frequencies. Uh, so gravitational waves
00:22:05 --> 00:22:08 caused by different phenomena. Have a
00:22:08 --> 00:22:11 very, very wide, uh, variation in
00:22:11 --> 00:22:14 frequency. Uh, some are, uh, what we call,
00:22:14 --> 00:22:17 uh. Well, let me just tell you the ones
00:22:17 --> 00:22:20 that we've observed so far. And that's
00:22:20 --> 00:22:22 because the particular gravitational wave
00:22:22 --> 00:22:25 detectors that we have. Are tuned effectively
00:22:25 --> 00:22:27 to these frequencies. They're the ones that
00:22:27 --> 00:22:29 come from colliding neutron stars,
00:22:29 --> 00:22:31 colliding black holes, all of that sort of
00:22:31 --> 00:22:32 thing we were just talking about a few
00:22:32 --> 00:22:35 minutes ago. Uh, and they are
00:22:35 --> 00:22:38 more or less in the, um, audio frequency
00:22:38 --> 00:22:41 spectrum. Uh, so if you amplified them
00:22:41 --> 00:22:43 enough, you could hear them. They're, uh, a
00:22:43 --> 00:22:46 few hundred hertz. One hertz is one
00:22:46 --> 00:22:48 cycle per second. But some of the
00:22:48 --> 00:22:51 bigger phenomena in the universe. And I'm
00:22:51 --> 00:22:53 thinking now of things like the Big Bang or
00:22:53 --> 00:22:56 the epoch of inflation times in the universe
00:22:56 --> 00:22:57 when things were very different from what
00:22:57 --> 00:23:00 they are now. They generate what we call
00:23:00 --> 00:23:03 nanohertz waves, where the frequencies,
00:23:03 --> 00:23:06 uh, are, uh, measured in, uh,
00:23:06 --> 00:23:08 billionths of a hertz rather than
00:23:09 --> 00:23:11 a few hundred hertz, uh,
00:23:12 --> 00:23:15 uh, so they would be detected in a
00:23:15 --> 00:23:16 completely different way. And in fact, we
00:23:16 --> 00:23:18 think. I think one of the ways of detecting
00:23:18 --> 00:23:20 them might be from the cosmic microwave
00:23:20 --> 00:23:22 background radiation, the flash of the Big
00:23:22 --> 00:23:25 Bang that we can still see. So you're right
00:23:25 --> 00:23:26 on the money, uh, with all of those
00:23:26 --> 00:23:29 questions. Yes, gravitational waves do behave
00:23:29 --> 00:23:32 almost in an analogous way to light. They
00:23:32 --> 00:23:34 certainly travel at the same speed of light.
00:23:34 --> 00:23:36 They can interfere, and they do come in
00:23:36 --> 00:23:37 widely different frequencies.
00:23:38 --> 00:23:39 Heidi Campo: Well, excellent. Thank you. Thank you so
00:23:39 --> 00:23:42 much, Fred. These have been wonderful answers
00:23:42 --> 00:23:45 to some wonderful questions. And thank you so
00:23:45 --> 00:23:47 much to everybody who has written in.
00:23:48 --> 00:23:50 Um, we really do have some of the
00:23:51 --> 00:23:54 best listeners here. I mean, this podcast,
00:23:54 --> 00:23:57 we have such an amazing, engaged
00:23:57 --> 00:23:59 audience. I mean, you guys are half of the
00:23:59 --> 00:24:01 show, really. Your questions are half of the
00:24:01 --> 00:24:04 show. Um, so please stay curious. Keep
00:24:04 --> 00:24:06 sending in your wonderful
00:24:06 --> 00:24:09 questions. Uh, it's certainly so fun
00:24:09 --> 00:24:12 for me to hear Fred, um, answer them
00:24:13 --> 00:24:14 and, ah, it's a good time.
00:24:15 --> 00:24:18 Um, Fred, do you have anything else you want
00:24:18 --> 00:24:20 to say before we sign off for today?
00:24:20 --> 00:24:22 Professor Fred Watson: No, just keep the questions coming in, folks,
00:24:22 --> 00:24:25 because this is the thing that makes SpaceNut
00:24:25 --> 00:24:28 special. We've got such a wide audience
00:24:28 --> 00:24:30 all over the world. We love hearing from you
00:24:30 --> 00:24:33 and we cover your questions, tricky ones or
00:24:33 --> 00:24:35 non tricky ones alike. Thank you.
00:24:35 --> 00:24:37 And thanks to you, Heidi, too.
00:24:37 --> 00:24:39 Heidi Campo: Oh, thank you, Fred. You're so sweet.
00:24:40 --> 00:24:42 All right, well, this has been, um, another Q
00:24:42 --> 00:24:45 and A episode of Space Nuts.
00:24:45 --> 00:24:47 We are, Heidi and Fred, signing off.
00:24:49 --> 00:24:51 Generic: You've been listening to the Space Nuts
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