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Supermassive Black Holes, Voyager's Journey & Gravitational Waves Explained | Q&A · Space Nuts: Astronomy Insights & Cosmic Discoveries

0:00
Speaker 1: Hello again, thanks for joining us on Space Nuts, where
0:02
Speaker 1: we talk astronomy and space and science all at the
0:06
Speaker 1: same time. This is a Q and A episode. My
0:09
Speaker 1: name is Andrew Dunctor, your host. Great to have your company.
0:12
Speaker 1: Coming up audience questions. We're going to answer a question
0:15
Speaker 1: from Martin about super massive black holes. Ben has also
0:20
Speaker 1: got a question about black holes and gravitational waves. And
0:23
Speaker 1: the Favorite train driver is on about a voyager one,
0:27
Speaker 1: and Judd has some thought experiments for us. We'll check
0:32
Speaker 1: it all out on this episode of Space.
0:34
Speaker 2: Nuts fifteen, Channel ten nine Ignition Siquench.
0:41
Speaker 3: Space Nuts Guy or three two one Space Nuts.
0:48
Speaker 4: As when I reported Neil's good.
0:52
Speaker 1: And back to unravel, unpack and solve all of that
0:56
Speaker 1: is Professor Fred Watson, Astronomer at Large. Hello Fred, Hello Andrew,
1:02
Speaker 1: very good to see you. Good to see you too.
1:04
Speaker 1: I've still got my crochie voice. In fact, I've been
1:06
Speaker 1: so unwell. I'm still wearing the same clothes as I
1:09
Speaker 1: was last week.
1:11
Speaker 3: Well there you go, funnily enough, so am I?
1:14
Speaker 1: Yeah? Well what a coincidence? Shall we get down to business?
1:22
Speaker 3: Why not?
1:22
Speaker 1: All right to do so? Yeah, Now we've got some
1:25
Speaker 1: text and audio questions we'll go text first today and
1:29
Speaker 1: forgive my rather unreliable voice as I work my way
1:33
Speaker 1: through this. Hi Fred and Andrew. It's Martin here from
1:36
Speaker 1: Heswall on the We're all in Merseyside. I posted a
1:41
Speaker 1: question before and Fred mentioned that he knew Barnston, which
1:45
Speaker 1: is just a pleasant walk over the fields from here.
1:49
Speaker 1: I have a question about your favorite topic, black hole.
1:52
Speaker 1: I thought it was going to be golf black holes.
1:55
Speaker 1: I'm interested specifically in the process of their formation, and
1:59
Speaker 1: more particularly in super massive black holes. The mechanism for
2:03
Speaker 1: the creation of stellar mass black holes seems to be
2:06
Speaker 1: well understood, but I find it hard to believe that
2:09
Speaker 1: this can be the same way that super massive black
2:13
Speaker 1: holes in the early universe were formed. I've read that
2:16
Speaker 1: the gravitational instability theory posits that black holes can be
2:20
Speaker 1: formed directly when a massive cloud of matter collapses under
2:24
Speaker 1: its own gravity. Why is it not possible that there
2:27
Speaker 1: can be two processes at work depending on the size.
2:31
Speaker 1: For me, part of the evidence in supporting in support
2:35
Speaker 1: of invoking gravitational instability is the lack of evidence for
2:39
Speaker 1: the existence of intermediate mass black holes. What are the
2:43
Speaker 1: arguments against this theory as it does seem to be
2:47
Speaker 1: that widely It doesn't seem to be that widely accepted.
2:50
Speaker 1: If black holes are created in two completely different ways,
2:53
Speaker 1: what effect would this have on their properties? For instance, charge, spin, etc.
2:58
Speaker 1: I really enjoy listening to the show. It helps me
3:01
Speaker 1: keep up to date with the world of science, space
3:04
Speaker 1: and stuff. That's our slogan. Ha, well done, well done, Martin,
3:09
Speaker 1: that's our slogan. Yeah. Look, that's a really good question.
3:13
Speaker 1: And we only talked in the last episode about the
3:16
Speaker 1: different theories about how black holes are formed and the
3:20
Speaker 1: possible discovery of primordial black holes. So if you haven't
3:24
Speaker 1: heard that episode, wind back because it's worth listening to
3:27
Speaker 1: that story. But yeah, it brings up an interesting point.
3:30
Speaker 1: How can it be the same process for a super
3:33
Speaker 1: massive black hole versus another one, a smaller one.
3:40
Speaker 3: Yeah? So, I mean Martin's hit on one of the
3:46
Speaker 3: key questions at the moment in astrophysics and cosmology. So
3:50
Speaker 3: he's right up to date there, sure is. Because this
3:54
Speaker 3: idea of the super massive black holes in the early universe,
3:59
Speaker 3: for directly as a direct result of a cloud of
4:03
Speaker 3: gas collapsing without having to go through the mechanisms forming
4:09
Speaker 3: a star and then the star is basically exploding to
4:13
Speaker 3: form a black hole. That's quite new, and that might
4:18
Speaker 3: be why, as Martin says, it's not yet sort of
4:21
Speaker 3: considered to be mainstream, but it is very much an
4:25
Speaker 3: up and coming idea and theory that answers the criticism
4:30
Speaker 3: that the conventional theory has, and that is, conventionally, scientists
4:37
Speaker 3: have assumed that super massive black holes are created over
4:43
Speaker 3: long periods of time by the accretion of material, So
4:51
Speaker 3: we know how a stellar mass black hole is formed
4:53
Speaker 3: exactly as Martin mentioned. We understand that a massive star
4:58
Speaker 3: explodes at the end of its life when the fuel
5:02
Speaker 3: balance runs out. The outer layers are shed off and
5:05
Speaker 3: a super and over remnant and the center, basically the
5:09
Speaker 3: central core, collapses to be the black hole, which is
5:12
Speaker 3: a point with zero dimensions, a point where density is infinite,
5:17
Speaker 3: so that the conventional method says you start off with
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Speaker 3: lots of those in a galaxy and they eventually accrete
5:27
Speaker 3: to form a bigger object, mixing with stuff that's sucked
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Speaker 3: in on the accretion disc as well. That might include
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Speaker 3: a few odd black holes dropping in to form eventually
5:39
Speaker 3: a super massive black hole. But the problem has been
5:43
Speaker 3: how do you manage to do that in less than
5:46
Speaker 3: a couple one hundred million years, which is you know
5:50
Speaker 3: where the earliest super massive black holes are after the
5:54
Speaker 3: Big Bang. We know about those because we can we
5:56
Speaker 3: measure them by look at using the James Webb space telescope.
6:01
Speaker 3: It's measured I think several objects within maybe two hundred
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Speaker 3: and fifty million years after the Big Bang. In other words,
6:09
Speaker 3: we're looking back almost thirteen point eight billion years thirteen
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Speaker 3: point six or something like that. How did they form
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Speaker 3: so quickly? If that's the mechanism, and that's why this
6:20
Speaker 3: alternative mechanism of direct collapse from an interstellar from a
6:25
Speaker 3: not interstellar because there were no stars then, but from
6:27
Speaker 3: a primordial gas cloud might have occurred. And as I
6:33
Speaker 3: understand it, the idea of primordial black holes postulated, this
6:41
Speaker 3: is what we talked about last week or the last episode,
6:44
Speaker 3: postulated by Stephen Hawking in visage that there would be
6:50
Speaker 3: a very very wide range of masses of black holes,
6:54
Speaker 3: ranging from things less than the mass of the Sun.
6:57
Speaker 3: As we reported in the last episode. We think we've
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Speaker 3: found one of those now to a supermassive black holes.
7:04
Speaker 3: I think that is all within the purview of Hawking's
7:09
Speaker 3: theory of primordial black holes. And so the question, you know,
7:14
Speaker 3: maybe the fact that we're finding the supermassive black holes
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Speaker 3: too early in the universe might to have been formed
7:23
Speaker 3: by stuff coming together, might be a support for the
7:26
Speaker 3: Hawking theory that maybe some of these were actually formed
7:29
Speaker 3: immediately after the Big Bang.
7:31
Speaker 1: Wow, wouldn't that be interesting?
7:33
Speaker 3: And there was something about something that Martin mentioned about intermediate.
7:38
Speaker 1: Yeah, he said, for me, part of the evidence in
7:42
Speaker 1: support of invoking gravitational instability is the lack of evidence
7:45
Speaker 1: for the existence of intermediate mass black holes, although they're
7:50
Speaker 1: the ones we were talking about recently.
7:52
Speaker 3: That we now have discovered, have we not, Yes, but
7:56
Speaker 3: there's still normally there still seem to be yes, much
8:00
Speaker 3: error than the super massive black holes or the stellar
8:03
Speaker 3: mass black holes which exist in profusion, intermediate mass black
8:08
Speaker 3: holes have been quite hard to find.
8:12
Speaker 1: Up.
8:13
Speaker 3: Yeah, I mean, you know, what Martin says is right,
8:17
Speaker 3: that might point to the idea of gravitational instability. In
8:23
Speaker 3: other words, sort of primordial type black holes as being
8:26
Speaker 3: the formation that might point to that. And so I
8:31
Speaker 3: don't think there's an issue there. But yes, his final question,
8:37
Speaker 3: if black holes are created in two completely different ways.
8:40
Speaker 3: What effect would that have on their properties? For example,
8:43
Speaker 3: for instance, charge, spin, et cetera. Now, in fact, the
8:47
Speaker 3: only properties of a black hole that you can observe
8:51
Speaker 3: are the charge in the spin as well as the mass,
8:55
Speaker 3: and that that's because of something that you and I
8:58
Speaker 3: might have mentioned before. Andrew something called the no hair theorem,
9:02
Speaker 3: which I'm very fond of, if you can guess, and
9:06
Speaker 3: no hair theorem basically says that there's you know, there's
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Speaker 3: virtually nothing of the black hole's characteristics that you can
9:16
Speaker 3: see from the outside. It's like suggesting a baldness of
9:19
Speaker 3: the of the black hole the event horizon. It doesn't
9:22
Speaker 3: give much away. Charge and spin are I think, I
9:26
Speaker 3: think only the only two apart from mass. Now I
9:29
Speaker 3: don't know the answer to that. Would there be any
9:31
Speaker 3: difference in those properties for two different methods of black
9:35
Speaker 3: hole formation. Thanks a really good question, and it's something
9:39
Speaker 3: that I probably should have a look at and see
9:41
Speaker 3: if I can find out.
9:42
Speaker 1: Yeah, I thought i'd look up no hair theorem to
9:45
Speaker 1: see what happened, and I didn't get an ad for
9:49
Speaker 1: a hair pill. It actually took me. It actually took
9:52
Speaker 1: me to the to the to the no hair theorrem
9:55
Speaker 1: the no hair theorem a bit of black holes. Yeah,
9:57
Speaker 1: so they go the internet actually worked. Yes, nice change,
10:03
Speaker 1: nice change, and a nice question, Martin. Thanks for sending
10:07
Speaker 1: that to us. Hopefully that helped you sort a few
10:09
Speaker 1: things out. But yeah, there's still a lot of theory
10:12
Speaker 1: around black holes yet to be proven. But we're chipping
10:15
Speaker 1: away at it. We are chipping away at it. Not
10:18
Speaker 1: me personally. I leave that to other people who are
10:20
Speaker 1: more astute. Thanks for sending it in. Our next question
10:24
Speaker 1: comes from our favorite train driver. His name is Andy.
10:29
Speaker 5: Train driver. Here, just a question for you on Voyager one.
10:34
Speaker 5: I know that he's currently traveling about thirty eight thousand
10:36
Speaker 5: miles per hour, and it's very low on fuel, and
10:40
Speaker 5: the fuel is used for the thrusters to point in
10:42
Speaker 5: the Santana's back to Earth. And I know that space
10:46
Speaker 5: is not empty. There's particles and space dust. So, because
10:50
Speaker 5: he've got such a long journey before he reaches anything significant,
10:54
Speaker 5: would the particles in space slow it enough to bring
10:58
Speaker 5: it to a halt, Because as far as I'm aware,
11:01
Speaker 5: it's got about forty thousand years before it reaches something significant.
11:05
Speaker 5: So is that a long enough time? Would you say
11:09
Speaker 5: to maybe not bring it to a halt, but to
11:12
Speaker 5: slow it significantly that it really does increase that timescale.
11:18
Speaker 5: Sorry if that doesn't make much sense. Thanks for your podcast, guys,
11:21
Speaker 5: really enjoy it.
11:22
Speaker 3: Speak to you soon.
11:23
Speaker 1: Bye. Thank you, Andy, Hope, Aul as well on your
11:27
Speaker 1: daily commute. Although you're the driver, so you just drag
11:30
Speaker 1: everyone else around. What a great job, right, okay? Voyager
11:35
Speaker 1: one thirty eight thousand miles an hour. Is there enough
11:39
Speaker 1: material to ultimately stop it because it's going to run
11:41
Speaker 1: into a few things here and there. Possibly, But I
11:44
Speaker 1: would question the spread of the dust when you get
11:47
Speaker 1: out into those interstellar places. The amount of material fins
11:52
Speaker 1: out significantly, doesn't it?
11:55
Speaker 3: Yeah, very much. So there is still you know, there
11:58
Speaker 3: are still atoms there or nucleari probably part of sub
12:02
Speaker 3: atomic particles.
12:05
Speaker 1: But it's not.
12:07
Speaker 3: It's not enough to significantly slow the spacecraft. It's you know,
12:17
Speaker 3: you're basically, to all intents and purposes, it's moving through
12:20
Speaker 3: a vacuum. It's I was thinking kilometers per second. Its
12:26
Speaker 3: current speed is sixteen point nine two zero kilometers per
12:31
Speaker 3: second relative to the Sun.
12:33
Speaker 1: Sixty one thousand kilometers an hour, seventeen kilometers a second
12:37
Speaker 1: dish thirty eight thousand mile Now, yep, it's going. It's fast.
12:41
Speaker 3: It is the speed I like is in units of
12:44
Speaker 3: astronomical units per year, and that is three point three
12:49
Speaker 3: point six nearly three point five six nine, So three
12:54
Speaker 3: times a year, it covers the distance from the Earth
12:58
Speaker 3: to the Sun.
12:59
Speaker 1: Yeah.
13:00
Speaker 3: Yeah, that's one hundred and fifty million kilometers.
13:03
Speaker 1: Sure is that's that's amazing, isn't it. And it's still
13:06
Speaker 1: going strong.
13:08
Speaker 3: Yeah, so, and it's right. I think the fuel's low.
13:11
Speaker 3: But the fuel is just for the thrusters. It's just
13:15
Speaker 3: to keep the antenna pointed towards Earth.
13:19
Speaker 1: So yeah, and he said it might come across something
13:23
Speaker 1: in about forty thousand years. I thought when we talked
13:27
Speaker 1: about this last that it could just keep going. It
13:30
Speaker 1: might not run into anything.
13:32
Speaker 3: Yeah, simply because it's not aimed at anything. And space
13:36
Speaker 3: is very empty. Even though there's a you know, four
13:39
Speaker 3: hundred billion stars in the Milky Way or whatever. The
13:42
Speaker 3: Milky Way is very very big, indeed, and it's look,
13:47
Speaker 3: it's it's distances. I think. I think the olds are
13:52
Speaker 3: that it will keep going forever. It might be captured
13:55
Speaker 3: by the gravity of another star. I think the notion
13:59
Speaker 3: of a collision is vanishingly small. I've just statistics just
14:06
Speaker 3: come into my head that I used to use a
14:08
Speaker 3: lot to give people the idea of just how big
14:12
Speaker 3: the galaxy is. And I'm sure you and I have
14:15
Speaker 3: discussed it too. If you imagine a diagram of our
14:18
Speaker 3: galaxy that was the size of the Earth, so twelve
14:23
Speaker 3: and a half a thousand kilometers in diameter, that's your
14:27
Speaker 3: map of the galaxy the size of the Earth. The
14:30
Speaker 3: separation from the Sun to the Earth on that scale
14:35
Speaker 3: is two millimeters. That tells you that the galaxy is very,
14:41
Speaker 3: very large compared with the size of the Solar System.
14:46
Speaker 1: That's just mind boggling stuff. It's really easily. And the
14:50
Speaker 1: other thing, I suppose we talk about the odd cloud,
14:53
Speaker 1: which is this thing around our Is it around the
14:58
Speaker 1: Solar system, around a galaxy? Apparently it's around the solar
15:01
Speaker 1: systolic system. They reckon it's going to take three hundred
15:05
Speaker 1: years for Voyager one to reach that. That's right, that's right,
15:11
Speaker 1: that it's a long which means it still hasn't really
15:14
Speaker 1: left our Solar system.
15:15
Speaker 3: In real terms, I'm not even sure that it will
15:18
Speaker 3: be three hundred years because the oak Cloud is about
15:21
Speaker 3: a light year away.
15:24
Speaker 1: Well, actually it says here the inner edge in three
15:28
Speaker 1: hundred years, but it will take thirty thousand years to
15:30
Speaker 1: pass through it. That's more like it.
15:32
Speaker 3: Yeah, it's more like it.
15:34
Speaker 1: I should have finished reading the sentence, shouldn't I there
15:39
Speaker 1: was There was an unpredictable full stop in there though,
15:42
Speaker 1: So yeah.
15:43
Speaker 3: But yeah, incredible. Sorry, I meant to say last time
15:48
Speaker 3: Andy came on, I meant to tell him that I'm
15:50
Speaker 3: a train driver too, But it's and scale, which he'll know.
15:56
Speaker 3: He'll know what that is. Not some people might not. Actually,
15:59
Speaker 3: probably quite a lot of our listeners do. But I
16:02
Speaker 3: drive my trains in and scale. I love it.
16:04
Speaker 1: I should send Andy if he sends me his email
16:07
Speaker 1: address some video of our brand new regional trains in
16:11
Speaker 1: New South Wales that are like to see that being
16:14
Speaker 1: fitted out in Dubbo where I live, and they've been
16:18
Speaker 1: doing test runs on them. I've actually heard it in
16:21
Speaker 1: the wee small hours passing by because it's got a
16:24
Speaker 1: completely different sound, and I've actually reached a point now
16:26
Speaker 1: where I recognize the different trains by sound. Hypathetic as that,
16:32
Speaker 1: but yeah, it's much much quieter than the current train
16:38
Speaker 1: which is the XPT, which is well past its use
16:41
Speaker 1: by date. But never let the New South Wales government,
16:45
Speaker 1: you know, build a train because they will. They will say, okay,
16:49
Speaker 1: it's got a twenty year life, so we'll replace it
16:51
Speaker 1: in fifty, because that's what's happening. But these are very slickly.
16:57
Speaker 1: These are Spanish trains that are being fitted out dubbo
17:00
Speaker 1: and really really lovely piece of kit as Fred would say. So,
17:06
Speaker 1: and he sent me your email address and I will
17:08
Speaker 1: send you a video of our new trains. It's weird
17:12
Speaker 1: watching them run around with nobody in them. It's just
17:16
Speaker 1: no passengers, nothing, just all the lights are on. Nobody's home.
17:20
Speaker 1: Nobody's home.
17:22
Speaker 3: Yeah, if you're on the Metro in Sydney, there's not
17:24
Speaker 3: even a driver on board either.
17:25
Speaker 1: Yeah, I know. I've been on the Metro a couple
17:28
Speaker 1: of times. It's a slick system. One of my boys
17:32
Speaker 1: lives in a suburb where they're just about to complete
17:34
Speaker 1: a metro line. So he's really happy about that because
17:37
Speaker 1: it'll get him to work, you know, three times as fast,
17:40
Speaker 1: so he's really he's thrilled because he got rid of
17:43
Speaker 1: his car. He doesn't use a car in Sydney doesn't
17:46
Speaker 1: see the need. Got to have one out here though
17:48
Speaker 1: in the country. Thanks Andy lovely to hear from you.
17:52
Speaker 1: This is Space Nuts with Andrew Dunkley and Professor Fred Watson.
17:58
Speaker 1: Let's take a short break from space Nuts to tell
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Speaker 1: nuts space nuts. Oh boy, okay o. Next question, I
19:38
Speaker 1: don't even know where we're up to. Where are we
19:40
Speaker 1: up to? We've spoken to Andy, You're right. Question three
19:43
Speaker 1: high space nuts. Ben Harding here from Kent, England. Having
19:47
Speaker 1: listened to your show for several years now, I know
19:50
Speaker 1: everything there is to know about black holes. Indeed, I
19:53
Speaker 1: am ready to start building my own any day now.
19:56
Speaker 1: But wait. If I build two and they crash together,
20:00
Speaker 1: they will create gravitational waves, and I need to account
20:03
Speaker 1: for the ensuing distortion of the fabric of space time.
20:06
Speaker 1: All my cats will be upset. So our gravitational waves
20:12
Speaker 1: spherical or flat? I'm thinking they must be spherical, But
20:16
Speaker 1: then again, if they are created by two objects spiraling
20:20
Speaker 1: in together, the waves may be flat by some sort
20:24
Speaker 1: of conservation of angular momentum rule. I hope you can
20:29
Speaker 1: help me with my cats. They get a bit scratchy
20:32
Speaker 1: when they're upset. Thanks for the awesome show, Ben. I
20:37
Speaker 1: thank you, Ben. I'm just imagining your cats freaking out
20:42
Speaker 1: over gravitational waves. There's a comic strip in that, I
20:45
Speaker 1: reckon somewhere. My brother would do a comic on that.
20:50
Speaker 1: I reckon. He's very artistic, is my brother? Okay? All right,
20:55
Speaker 1: So our gravitational waves from the cataclysmic collision of two
21:00
Speaker 1: black holes spherical.
21:04
Speaker 3: So I think what Ben is referring to in his
21:10
Speaker 3: description is whether they whether they're they're radiated. Gravitational waves
21:16
Speaker 3: are radiated in all directions what we would call isotropic,
21:20
Speaker 3: or just in a plane, in the plane of the collision.
21:24
Speaker 3: And to the best of my understanding, the answer is
21:28
Speaker 3: that they're isotropic. They go off in all directions. So
21:31
Speaker 3: space shutters are just because of the gravitational interaction. It's
21:37
Speaker 3: not got any prefer I don't think. I do not
21:41
Speaker 3: believe it's got any preferred direction because of the you know,
21:44
Speaker 3: the direction of the collision. I think it's it's the
21:47
Speaker 3: same in all directions. There's another way of interpreting Ben's question, though,
21:53
Speaker 3: and that is how the oscillations of gravitational waves take place.
22:01
Speaker 3: And they're not the same as sound waves, where which
22:05
Speaker 3: are compression waves where things push backwards and forwards. And
22:09
Speaker 3: they're not the same as light waves, which are transverse
22:12
Speaker 3: waves where the electric field and magnetic field vary in
22:16
Speaker 3: a transverse manner, in other words, opposite to the direction
22:20
Speaker 3: of propagation, or right angles to the direction of propagation.
22:24
Speaker 3: There's something called quadruple waves, which is a sort of
22:27
Speaker 3: combination of not quite a combination of the two, but
22:31
Speaker 3: certainly a slightly unusual form of transverse wave. Quadruple waves
22:37
Speaker 3: is what they are. But I don't think that's what
22:39
Speaker 3: he means. I think what Ben means is what I
22:42
Speaker 3: answered in the first place, that yes, they're isotropic, rather
22:45
Speaker 3: than limited to a particular plane.
22:48
Speaker 1: They go out in all directions, unlike the gravitational wave
22:51
Speaker 1: that I detected on a plane. I don't know what
22:54
Speaker 1: that guy was eating, but yeah, I hope I don't
22:57
Speaker 1: have to experience a kid.
23:00
Speaker 3: Yeah, I know those things as well.
23:02
Speaker 1: Pretty awful stuff. Really. I'm impressed that Ben says he
23:07
Speaker 1: knows everything there is to know about black holes. Does
23:10
Speaker 1: that mean we've been doing a job That means he
23:15
Speaker 1: knows more than us, which, yeah, well it is to
23:17
Speaker 1: do possible too. Yeah, yes, but we're learning more and
23:20
Speaker 1: more about them.
23:22
Speaker 3: But that's of course we're listening to our listeners.
23:24
Speaker 1: That's that's exactly right. But yeah, there've been the topic
23:29
Speaker 1: of I think since we started a decade ago. Fred,
23:33
Speaker 1: you reminded me earlier it's been ten years we've been
23:36
Speaker 1: doing this podcast. That's that's extraordinary. We should have had
23:40
Speaker 1: a party, but I think we just can't stay up
23:42
Speaker 1: that late anymore. But it's it's probably been the hottest
23:48
Speaker 1: topic on Space Nuts since day one. Is black holes,
23:52
Speaker 1: closely followed by dark matter, dark energy, and I don't
23:57
Speaker 1: know where you go from there, but it's been a
23:58
Speaker 1: life in space. Yes, life, Yes, you are right. Those
24:02
Speaker 1: are the top four topics. So I expect next week
24:05
Speaker 1: our four questions will be on black hole's, dark matter,
24:08
Speaker 1: dark energy and life elsewhere.
24:11
Speaker 3: There's a good chance they will. That will be the standard.
24:16
Speaker 1: Yep, very good, Thank you, Ben. Lovely to hear from you.
24:19
Speaker 1: Hope all is well in Kent. Our final question comes
24:24
Speaker 1: from Judd.
24:26
Speaker 2: Goody, Fred and Andrew. It's Judd from Brisbane. Been a
24:30
Speaker 2: big fan of the show for a long time. My
24:33
Speaker 2: wife and I were listening to a recent episode where
24:38
Speaker 2: one of the stories was about the spun out asteroid
24:41
Speaker 2: that's spinning at an incredibly fast rate. And you know,
24:46
Speaker 2: we found Andrew's thought experiments about how that would affect
24:52
Speaker 2: Earth if we were spinning at a similar rate, And yeah,
24:57
Speaker 2: I got my head spinning and came up with lots
25:00
Speaker 2: of other thought experiments. First, my question is what is
25:06
Speaker 2: the current speed of the Earth's rotation? And yeah, does
25:14
Speaker 2: that speed affect the pull of gravity that.
25:20
Speaker 3: We feel on Earth?
25:23
Speaker 2: Like for instance, if I weigh one hundred kilograms at
25:28
Speaker 2: spinning at this rate of speed, if the Earth stops
25:32
Speaker 2: spinning tomorrow, would I weigh significantly more? Just wondering about that.
25:40
Speaker 2: And another question, would I weigh less at the equator
25:47
Speaker 2: than I would standing at the North or Soft pole
25:51
Speaker 2: because the equator is spinning much more rapidly than the
25:55
Speaker 2: Earth is at the poles. So just some thoughts to
26:00
Speaker 2: make your head spin and maybe give me some answers.
26:04
Speaker 1: Thank you, Thank you, jud Thanks to you and your
26:07
Speaker 1: wife for being fans of the show for so long.
26:09
Speaker 1: Much appreciated. And we can make this quick, yes, and
26:13
Speaker 1: we're finished for that. No, there's a lot more to
26:16
Speaker 1: it than that, but I think he pretty well nailed
26:20
Speaker 1: a few of the thoughts that he's had in terms
26:22
Speaker 1: of what the answers are, what is the current speed
26:25
Speaker 1: of Earth's rotation? If you listen to the Monty Python
26:27
Speaker 1: song from the Life of Brian or was it one
26:30
Speaker 1: of the others, Yeah, they were wrong, weren't they with
26:35
Speaker 1: their assessment of the speed of the rotation of the planet.
26:42
Speaker 3: I can't remember. I do remember, I don't know what
26:46
Speaker 3: the speed is. I'll get to that in a second.
26:48
Speaker 3: I can't remember what the song says, but I do
26:49
Speaker 3: remember listening to that song a long time ago and thinking, yeah,
26:53
Speaker 3: pretty well, most of the astronomical statistics in it are correct,
26:58
Speaker 3: or they were when it was written in the day.
27:01
Speaker 3: But Jod is right. The speed of rotation at the
27:06
Speaker 3: Earth on the equator, which is where your linear speed
27:10
Speaker 3: is maximum, is sixteen hundred kilometers an hour. So that's significant.
27:17
Speaker 3: It's about half a kilometer per second roughly, and that's
27:23
Speaker 3: why you tend to build space launch sites at the equator,
27:27
Speaker 3: because you've got that additional zero point five kilometers per second.
27:32
Speaker 3: That's quite significant when you're trying to get up to
27:34
Speaker 3: eight kilometers per second to get into orbit. So you're
27:38
Speaker 3: kind of a sixteenth of the way they're already just
27:41
Speaker 3: by putting your launch site on the equator and of
27:43
Speaker 3: course launching towards the east, which is the direction that
27:46
Speaker 3: we're rotating in a middle latitudes. It reduces at our
27:51
Speaker 3: latitude here in New South Wales it's about fourteen hundred
27:55
Speaker 3: kilometers per hour. At Jud's latitude in Brisbane it's a
28:00
Speaker 3: little bit less, not that much less though, But so
28:06
Speaker 3: what's the effect on your weight? That's the interesting thing,
28:09
Speaker 3: And there are two parts to this. One is kind
28:18
Speaker 3: of what we've just alluded to, the fact that you
28:20
Speaker 3: are rotating sixteen hundred kilometers an hour roughly one thousand
28:27
Speaker 3: miles an hour. It basically there's a centrifugal force that
28:30
Speaker 3: means that you are slightly lighter. Your mass doesn't change,
28:35
Speaker 3: of course, but your weight does because of that centrifugal force.
28:40
Speaker 3: But there is another effect that acts with that too,
28:45
Speaker 3: and that's because the Earth isn't sphery cool. It's slightly
28:49
Speaker 3: bulging in the centric it's what we call and a
28:51
Speaker 3: blazed as spheroid. And at the equator you're about twenty
28:58
Speaker 3: kilometers are further away from the center of gravity then
29:04
Speaker 3: you are at the poles and so that too reduces
29:09
Speaker 3: the gravitational poll that you feel. So those two things together,
29:14
Speaker 3: the equatorial bulge of the Earth and the centrifugal force
29:17
Speaker 3: of the Earth's rotation come they basically combine to give
29:22
Speaker 3: you a figure that's a bit less than one percent
29:26
Speaker 3: of your weight changes if you're at the equator compared
29:30
Speaker 3: with the pole. People maybe, yes, yeah, I mean it
29:34
Speaker 3: means that if you do weigh one hundred kilograms then
29:37
Speaker 3: at the equator, then you're only going to be ninety
29:39
Speaker 3: nine at the pole. No, I've got it another way around.
29:43
Speaker 3: If you're a hundred kilos at the pole, you're only
29:45
Speaker 3: going to be ninety nine at the equator.
29:47
Speaker 1: I knew what you mean. Yeah, yeah, it's fascinating really
29:52
Speaker 1: and yeah, that was one of his questions, weight at
29:58
Speaker 1: the equator versus the part what would happen if Earth
30:04
Speaker 1: stops spinning? Like, I think we'd all be doomed for
30:08
Speaker 1: starters that the.
30:09
Speaker 3: Right, But we'd all be projected eastwards at sixteen hundred
30:14
Speaker 3: kilometers an hour if you're on the equator, Yeah.
30:17
Speaker 1: Yeah, that'd be pretty messy.
30:20
Speaker 3: But yeah, but if they are stopped spinning, you'd only
30:24
Speaker 3: have that equatorial bulge component that's reducing your weight, the
30:29
Speaker 3: fact that you're a little bit further away from the center,
30:31
Speaker 3: and that's almost negligible on its own.
30:33
Speaker 1: Yeah, fair enough, that was easy. And I found that
30:37
Speaker 1: mudy Python song. It was from the meaning of life,
30:40
Speaker 1: not from the life of Brian, and it's called the
30:43
Speaker 1: Galaxy Song. And the first verse, first verse is just
30:47
Speaker 1: remember that you're standing on a planet that's evolving and
30:49
Speaker 1: revolving at nine hundred miles an.
30:52
Speaker 3: Hour, which is yeah, all right, so it's it's there's
30:58
Speaker 3: a bit one hundred miles an hour slow, yes, but
31:02
Speaker 3: it rhymes that's it a thousand works Yeah.
31:09
Speaker 1: Oh well maybe they needed two words rather than no,
31:12
Speaker 1: I would have still been or Andrew.
31:15
Speaker 3: Maybe the Earth has speed it up since they recorded
31:17
Speaker 3: the song.
31:18
Speaker 1: That's what it's slowing down though, isn't it. Yes, yeah,
31:24
Speaker 1: well eventually this song will be right, Yes, it will.
31:30
Speaker 3: That's right.
31:31
Speaker 1: Good, all right, thank you so much. Jud lovely to
31:34
Speaker 1: hear from you. I hope all is well in Brisbane.
31:38
Speaker 1: Sorry about your football team not and I think that
31:42
Speaker 1: brings us to the end. If you have questions for us,
31:45
Speaker 1: we would love to hear from you. You can go
31:48
Speaker 1: to our website Space Nuts dot Io and click on
31:51
Speaker 1: the am a link at the top of the page
31:55
Speaker 1: where you can ask me anything or ask me and
31:57
Speaker 1: I'll give it to Fred to figure out. So send
32:01
Speaker 1: us text and audio questions. Don't forget to tell us
32:03
Speaker 1: who you are and where you're from. And a little
32:05
Speaker 1: request if you will. When you next listen or are
32:09
Speaker 1: listening to us right now, please leave a review on
32:12
Speaker 1: whatever podcast platform you use, because reviews are very handy.
32:18
Speaker 1: It sort of moves us up some lattery thing ranking thing,
32:24
Speaker 1: which is very good for us. Apparently, I don't understand
32:28
Speaker 1: how this works. It's all to do with gravity. And
32:33
Speaker 1: thank you Fred once again for helping us out today.
32:36
Speaker 1: I think he did all the work.
32:37
Speaker 3: Actually, nice to help Andrew, always good to talk and
32:42
Speaker 3: we'll touch off again.
32:43
Speaker 1: We will Professor Fred Watson, Astronomer at Large. And thanks
32:47
Speaker 1: to Hugh in the studio although he couldn't be with
32:51
Speaker 1: us today. He had a thought and it was experimental
32:57
Speaker 1: and he's going to go and investigate at right now
33:00
Speaker 1: and see if it's real. I don't know what that means.
33:04
Speaker 1: And from me Andrew Dunkley, thanks to your company. You
33:06
Speaker 1: will see you on the next episode of Space Nuts
33:08
Speaker 1: Bye Bye.
33:10
Speaker 4: You'll be listening to the Space Nuts podcast, available at
33:15
Speaker 4: Apple Podcasts, Spotify, iHeartRadio, or your favorite podcast player. You
33:20
Speaker 4: can also stream on demand at bytes dot com.
33:24
Speaker 1: This has been another quality podcast production from nights dot com.