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Space Nuts: Vanishing Stars, White Holes, Earth’s Mass and Neutrinos
In this listener Q&A episode of Space Nuts, Andrew Dunkley and Professor Fred Watson tackle four cosmic questions that stretch from distant stars to the nature of space-time. They explain why a star billions of light-years away would still appear in our sky long after it had gone out, and why looking across the universe means looking back through time. Next, they consider whether white holes are the opposite of black holes, then investigate whether dark matter could affect our measurements of Earth’s mass and gravity. Finally, they explore how neutrinos interact with gravity, whether black holes can capture them, and why space-time itself is not something a black hole can consume. Join Andrew and Fred Watson Watson for big ideas, listener curiosity and the occasional detour into the value of the Earth in dollars.
Key topics
- How light-travel time means we see distant stars as they were in the past.
- White holes as theoretical solutions to relativity, and how they differ from black holes.
- Whether dark matter contributes to Earth’s measured gravity and mass.
- The mass of the Earth and how astronomers determine it.
- Neutrinos, gravity, black holes and whether space-time can be consumed.
Timestamps
00:00 - Introduction and listener questions
01:30 - If a distant star goes out, when would we see it happen?
06:30 - Looking back in time across the observable universe
10:00 - What are white holes, and are they the opposite of black holes?
15:30 - Could dark matter affect measurements of Earth’s gravity?
20:30 - How the mass of Earth is determined
23:30 - Do neutrinos interact with gravity, and can black holes capture them?
27:00 - Could a black hole feed on space-time itself?
30:00 - How to send questions to Space Nuts and closing remarks
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00:00:00 --> 00:00:02 Andrew Dunkley: Hi, there. Thanks for joining us on a Q and A
00:00:02 --> 00:00:05 edition of Space Nuts. And this is where
00:00:05 --> 00:00:08 we answer audience questions. And we've got a
00:00:08 --> 00:00:10 whole bunch today. We're going to talk about
00:00:10 --> 00:00:13 the light of a distant, uh, star
00:00:13 --> 00:00:14 or the lack of.
00:00:14 --> 00:00:17 And what happens when the star goes out and
00:00:17 --> 00:00:19 the light, you know, where does it go? Do we
00:00:19 --> 00:00:21 see it? Do we not? We'll tell you all about
00:00:21 --> 00:00:24 that. Um, black holes versus white
00:00:24 --> 00:00:27 holes. That's, uh, an old chestnut that comes
00:00:27 --> 00:00:30 up from time to time. Uh, the mass of the
00:00:30 --> 00:00:33 Earth is, um, something that
00:00:33 --> 00:00:35 somebody wants to know about. And we talked
00:00:35 --> 00:00:37 about black holes and white holes. What about
00:00:37 --> 00:00:40 neutrinos versus black holes? We'll answer
00:00:40 --> 00:00:42 all of that or not on this episode
00:00:42 --> 00:00:44 of space nuts.
00:00:44 --> 00:00:46 Professor Fred Watson: 15 seconds. Guidance is internal.
00:00:47 --> 00:00:49 10, 9. Ignition
00:00:49 --> 00:00:50 sequence start.
00:00:50 --> 00:00:53 Generic: Space nuts. 5, 4, 3. 2. 1. 2,
00:00:53 --> 00:00:54 3, 4,
00:00:54 --> 00:00:57 Generic: 5, 5, 4, 3, 2, 1. Space
00:00:57 --> 00:00:59 nuts. Astronauts report it feels good.
00:01:01 --> 00:01:03 Andrew Dunkley: Here again to try and solve all of that is
00:01:03 --> 00:01:05 Professor Fred Watson Watson, astronomer at
00:01:05 --> 00:01:05 Large. Hi, Fred Watson.
00:01:07 --> 00:01:09 Professor Fred Watson: Nice, um, to see you again. You, too,
00:01:09 --> 00:01:11 Fred Watson. Still at large as well.
00:01:11 --> 00:01:14 Andrew Dunkley: Yes, uh, I'm less large. I just. I've been
00:01:14 --> 00:01:16 losing weight lately, which isn't a bad
00:01:16 --> 00:01:18 thing. Isn't a bad thing.
00:01:18 --> 00:01:18 Professor Fred Watson: Okay,
00:01:19 --> 00:01:20 Andrew Dunkley: I'm back to manageable levels.
00:01:21 --> 00:01:23 Professor Fred Watson: Well, that's good. Well, congratulations on
00:01:23 --> 00:01:23 that.
00:01:23 --> 00:01:25 Andrew Dunkley: Thank you. Yeah, I think it's the first time
00:01:25 --> 00:01:27 in a decade I've been under 80 kilos.
00:01:29 --> 00:01:32 Professor Fred Watson: Um. Oh, that's, um. That's quite light.
00:01:32 --> 00:01:32 Andrew Dunkley: Yeah, for
00:01:32 --> 00:01:33 Professor Fred Watson: somebody your height.
00:01:34 --> 00:01:37 Andrew Dunkley: It's about right for my height. Okay.
00:01:37 --> 00:01:37 Professor Fred Watson: M.
00:01:38 --> 00:01:41 Andrew Dunkley: But, um, yeah, it's taken
00:01:41 --> 00:01:44 a while, but by design, slow and
00:01:44 --> 00:01:45 steady is the way to do it.
00:01:45 --> 00:01:45 Professor Fred Watson: That's a great thing.
00:01:45 --> 00:01:47 Andrew Dunkley: Yeah, I took my sweet time about it, that's
00:01:47 --> 00:01:50 for sure. All right,
00:01:50 --> 00:01:53 um, we've got some questions to deal with.
00:01:53 --> 00:01:54 Do you want to hear the first one?
00:01:55 --> 00:01:58 Professor Fred Watson: Um, I could say. Let me guess.
00:01:58 --> 00:01:59 But, um, I might hear it instead.
00:01:59 --> 00:02:01 Andrew Dunkley: All right, this comes from Billy.
00:02:02 --> 00:02:05 Billy Gerard: Professor Watson. Andrew. Billy
00:02:05 --> 00:02:07 Gerard here in New Jersey on the great
00:02:07 --> 00:02:10 old big old US Of A. Quick
00:02:10 --> 00:02:13 question. Let's just say, hypothetically, uh,
00:02:13 --> 00:02:15 we are looking at a star that's a billion
00:02:15 --> 00:02:18 light years away. And we're so. So
00:02:18 --> 00:02:19 theoretically, we're looking back in time a
00:02:19 --> 00:02:21 billion years. Now, hypothetically, let's
00:02:21 --> 00:02:24 just say that one day that star just
00:02:24 --> 00:02:27 goes out. It stops raining.
00:02:28 --> 00:02:31 Like, would we still see that star for,
00:02:31 --> 00:02:33 like. Like, does that light that's on its way
00:02:33 --> 00:02:35 to us keep coming? Like, would it take a
00:02:35 --> 00:02:37 billion years before we saw it go out?
00:02:38 --> 00:02:40 How does that work? Help me Understand that.
00:02:40 --> 00:02:42 By the way. Love you guys, Love you both,
00:02:42 --> 00:02:44 Love the podcast, love hearing you. And um,
00:02:45 --> 00:02:47 I, boy, I go all the way. I've been listening
00:02:47 --> 00:02:48 to you guys for a really long time. So I
00:02:48 --> 00:02:50 really appreciate the podcast and everything
00:02:50 --> 00:02:53 you do and thanks so much for uh, taking
00:02:53 --> 00:02:55 a call. Billy Gerard here in New, uh,
00:02:56 --> 00:02:57 Jersey, US of A.
00:02:59 --> 00:03:01 Andrew Dunkley: Thank you Billy. Uh, so lovely to hear from
00:03:01 --> 00:03:03 you and I'm glad you've been a long term
00:03:03 --> 00:03:05 listener and uh, glad you finally got through
00:03:05 --> 00:03:08 to us with a question. Uh, this, this sort of
00:03:08 --> 00:03:11 uh, is the same or similar to the question
00:03:11 --> 00:03:14 that we had recently. The hypothetical about
00:03:14 --> 00:03:17 the sun suddenly switching off and how much
00:03:17 --> 00:03:20 light we would see. Like if, if it switched
00:03:20 --> 00:03:22 off right now, we wouldn't see
00:03:22 --> 00:03:25 that happen for another eight and a bit
00:03:25 --> 00:03:26 minutes. Eight minutes, 20 seconds or
00:03:26 --> 00:03:29 something to that effect. It's the same for
00:03:29 --> 00:03:31 stars all over the universe, is it not?
00:03:32 --> 00:03:33 Professor Fred Watson: Yes it is,
00:03:33 --> 00:03:34 Andrew Dunkley: except that it'll be longer than 8 minutes
00:03:34 --> 00:03:35 and 20 seconds.
00:03:35 --> 00:03:38 Professor Fred Watson: That's right. So it's the same principle that
00:03:38 --> 00:03:41 light travels at uh, that
00:03:41 --> 00:03:44 rapid speed of 300 kilometres
00:03:44 --> 00:03:47 per second or in units that
00:03:48 --> 00:03:51 um, anybody in the USA will understand. One
00:03:51 --> 00:03:53 foot in a billionth of a second. Uh,
00:03:55 --> 00:03:57 so yeah, that's quite convenient actually
00:03:57 --> 00:03:59 that it's uh, a foot in a billionth of a
00:03:59 --> 00:04:02 second. Um, so yes, so
00:04:02 --> 00:04:05 that's exactly how it works. I mean
00:04:05 --> 00:04:08 there's always the analogue of um,
00:04:09 --> 00:04:12 sound when we
00:04:12 --> 00:04:15 listen to something, a noise made by
00:04:15 --> 00:04:17 something at a distance, for example, uh,
00:04:17 --> 00:04:19 lightning. And there was plenty of lightning
00:04:19 --> 00:04:21 around here last night, a huge flash.
00:04:21 --> 00:04:23 Andrew Dunkley: I've seen some of the footage.
00:04:23 --> 00:04:25 Professor Fred Watson: Yeah, uh, you get a flash, um,
00:04:26 --> 00:04:29 and then it takes, well, it takes
00:04:29 --> 00:04:31 sometimes minutes, several minutes for the
00:04:31 --> 00:04:34 uh, sorry, several seconds for the sound to
00:04:34 --> 00:04:37 reach you. Um, and so if you, you
00:04:37 --> 00:04:38 know, if the only way you knew about this
00:04:38 --> 00:04:41 thing was by the sound, uh, you'd be
00:04:41 --> 00:04:43 listening in the past as it were, because of
00:04:43 --> 00:04:46 that several seconds that it took. Uh,
00:04:46 --> 00:04:48 and it's true with uh, stars, whether they
00:04:48 --> 00:04:51 are as near as the sun is and you're
00:04:51 --> 00:04:54 exactly 8 minutes and 20 seconds is the light
00:04:54 --> 00:04:56 time from the sun to the earth. We wouldn't
00:04:56 --> 00:04:59 know anything about it until 8 minutes and 20
00:04:59 --> 00:05:02 seconds had gone by after the sun had managed
00:05:02 --> 00:05:05 to disappear or become extinct or ah,
00:05:05 --> 00:05:08 whatever. Um, and as we've spoken about
00:05:08 --> 00:05:10 before, gravity actually would work the same
00:05:10 --> 00:05:12 way because gravity, uh, also our
00:05:12 --> 00:05:15 gravitational waves also travel at the speed
00:05:15 --> 00:05:17 of light or the impulse of gravity.
00:05:17 --> 00:05:20 So yeah, uh, it's absolutely right, Billy,
00:05:20 --> 00:05:22 you're looking back in time and you're
00:05:22 --> 00:05:24 looking back in time sometimes a long way.
00:05:24 --> 00:05:27 Um, certainly, um,
00:05:27 --> 00:05:29 the most distant things that we can see,
00:05:30 --> 00:05:32 we're seeing them as they were when the
00:05:32 --> 00:05:34 universe was only about 300 million years
00:05:34 --> 00:05:36 old. So you're looking back Almost the whole
00:05:36 --> 00:05:38 13.8 billion year history of the universe,
00:05:38 --> 00:05:40 which is staggering really.
00:05:41 --> 00:05:44 Andrew Dunkley: It is. Uh, and just for the record, uh,
00:05:44 --> 00:05:47 the furthest star, ah, ever detected at
00:05:47 --> 00:05:50 this point in time is 12.9
00:05:50 --> 00:05:50 billion
00:05:52 --> 00:05:52 Professor Fred Watson: light
00:05:52 --> 00:05:53 Andrew Dunkley: years from Earth.
00:05:53 --> 00:05:56 Professor Fred Watson: That's right. So, um, um, that means,
00:05:56 --> 00:05:58 you know, it emitted its light when the
00:05:58 --> 00:06:01 universe was 900 million years old.
00:06:01 --> 00:06:04 Um, and I do remember reading about that, uh,
00:06:04 --> 00:06:06 some time ago, in fact, we probably covered
00:06:06 --> 00:06:08 it on space notes. And the only reason we
00:06:08 --> 00:06:11 could see a single star is because it's
00:06:11 --> 00:06:14 gravitationally lensed. It's being magnified
00:06:14 --> 00:06:17 by the gravitational distortion of
00:06:17 --> 00:06:19 a cluster of galaxies in front of it. So we
00:06:19 --> 00:06:21 can see an individual star at that distance.
00:06:22 --> 00:06:25 Andrew Dunkley: But I don't, I can't remember what the number
00:06:25 --> 00:06:27 Billy said was. 10 billion or
00:06:27 --> 00:06:28 Professor Fred Watson: one, uh,
00:06:28 --> 00:06:28 Andrew Dunkley: billion.
00:06:28 --> 00:06:30 Professor Fred Watson: Yeah, I think he said 10 billion.
00:06:30 --> 00:06:30 Andrew Dunkley: Yeah. So
00:06:30 --> 00:06:32 Professor Fred Watson: sorry. No, he said a billion. A billion.
00:06:32 --> 00:06:35 Andrew Dunkley: So if a star a billion light years away,
00:06:35 --> 00:06:37 Billy, just suddenly went out right now,
00:06:38 --> 00:06:39 you'd have to set your watch
00:06:41 --> 00:06:43 to go off in a billion years,
00:06:44 --> 00:06:46 basically, give or take because of
00:06:46 --> 00:06:48 gravitational lensing and other, other
00:06:48 --> 00:06:51 effects. Um, but it would take that
00:06:51 --> 00:06:53 long for you to see it go out.
00:06:54 --> 00:06:55 It's just hard to get your head around that
00:06:55 --> 00:06:57 sometimes, isn't it? Um,
00:06:58 --> 00:07:00 everything's finite, even light. I mean,
00:07:01 --> 00:07:02 there's a limit.
00:07:03 --> 00:07:05 Professor Fred Watson: I think what's almost more
00:07:05 --> 00:07:08 profound is that um, our ah, view of the
00:07:08 --> 00:07:10 universe doesn't matter. Whether you're
00:07:10 --> 00:07:12 talking about individual stars or
00:07:13 --> 00:07:15 galaxies or nebulae or whatever, we are
00:07:15 --> 00:07:18 always looking into the past. So,
00:07:18 --> 00:07:20 you know, when we look outwards, we're just
00:07:20 --> 00:07:22 looking further and further and further back
00:07:22 --> 00:07:25 in time. It's why we talk about space time,
00:07:25 --> 00:07:27 because space and time are so intimately
00:07:27 --> 00:07:30 related. Um, and
00:07:30 --> 00:07:33 that means because gravity also
00:07:33 --> 00:07:35 works on that speed limit, um,
00:07:37 --> 00:07:38 there's no point in really thinking about
00:07:39 --> 00:07:41 things in what we might think of as
00:07:41 --> 00:07:44 an absolute sense where you're looking at the
00:07:44 --> 00:07:45 universe from outside and seeing everything
00:07:45 --> 00:07:48 in it happening, uh, you know,
00:07:48 --> 00:07:51 simultaneously almost. Um, it's
00:07:51 --> 00:07:53 always, um, modified by our
00:07:53 --> 00:07:56 view. The fact that we are at the centre of
00:07:56 --> 00:07:59 an observing sphere. We're only
00:07:59 --> 00:08:01 an imaginary point and, you know, there's
00:08:01 --> 00:08:03 nothing significant about where we are. But
00:08:03 --> 00:08:06 it means that our whole sphere of
00:08:06 --> 00:08:09 observation has this time gradient
00:08:09 --> 00:08:11 across it Going back right to the Big Bang
00:08:11 --> 00:08:13 itself. Because we can still see the flash of
00:08:13 --> 00:08:15 the Big Bang in the cosmic radiation,
00:08:15 --> 00:08:15 Andrew Dunkley: cosmic
00:08:15 --> 00:08:16 Professor Fred Watson: background radiation.
00:08:16 --> 00:08:19 Andrew Dunkley: It's incredible. Uh, I was reading an
00:08:19 --> 00:08:22 article, uh, on the
00:08:22 --> 00:08:25 weekend, uh, about a scientist who was,
00:08:25 --> 00:08:27 um, quite prominent in the past. I can't
00:08:27 --> 00:08:29 think of his name right now, but, uh, he kind
00:08:29 --> 00:08:32 of got debunked or criticised or
00:08:32 --> 00:08:34 laughed at, whatever you like, for coming up
00:08:34 --> 00:08:36 with the theory that our existence
00:08:36 --> 00:08:39 is based purely on consciousness. That the
00:08:39 --> 00:08:41 universe and everything that's happening in
00:08:41 --> 00:08:44 it exists because we are
00:08:45 --> 00:08:48 sentient beings, that we are creating all of
00:08:48 --> 00:08:51 this. Um, it is so hard to.
00:08:52 --> 00:08:54 Professor Fred Watson: I think that's called the head. I think
00:08:54 --> 00:08:57 that's the strong anthropic principle.
00:08:57 --> 00:08:57 I
00:08:57 --> 00:09:00 Andrew Dunkley: think that's exactly what it was. Yes. Um,
00:09:00 --> 00:09:02 I can't remember why it came up. It was
00:09:02 --> 00:09:04 probably just one of those news feeds that
00:09:04 --> 00:09:06 pops up from time to time. But, uh, yeah,
00:09:06 --> 00:09:09 it's a fascinating theory. Um,
00:09:09 --> 00:09:11 there are those who believe you can
00:09:11 --> 00:09:14 manipulate that to your advantage, but I
00:09:14 --> 00:09:16 don't know if that's true or not. Um, there
00:09:16 --> 00:09:19 was a famous case of a woman who claimed, um,
00:09:19 --> 00:09:22 that she could and she won more
00:09:22 --> 00:09:24 prizes than anyone in history or something.
00:09:24 --> 00:09:27 Like there's some strange stories out there.
00:09:27 --> 00:09:29 Could just be coincidence. That's another
00:09:29 --> 00:09:31 theory as well. Thank you, Billy. Uh,
00:09:31 --> 00:09:34 awesome to hear from you in the lovely state
00:09:34 --> 00:09:37 of New Jersey. Our next question on
00:09:37 --> 00:09:40 Space nuts, Fred Watson, comes from Tristan,
00:09:40 --> 00:09:43 uh, and Simon. Simon's the dad, Tristan's
00:09:43 --> 00:09:45 his son. My 9 year old son Tristan. See, I
00:09:45 --> 00:09:47 was right. Uh, and I.
00:09:49 --> 00:09:52 My 9 year old son Tristan and I listen to
00:09:52 --> 00:09:54 your podcast on our, uh, daily drive to
00:09:54 --> 00:09:57 school. And he has a question among many.
00:09:57 --> 00:10:00 Tristan is interested in black holes and has
00:10:00 --> 00:10:03 heard about the theoretical idea of a white
00:10:03 --> 00:10:05 hole. His question is if black holes
00:10:05 --> 00:10:08 have extremely high gravity, are, uh, white
00:10:08 --> 00:10:11 holes the opposite? Thank you for keeping us
00:10:11 --> 00:10:14 entertained and curious during our long
00:10:14 --> 00:10:16 commute, Tristan and Simon.
00:10:17 --> 00:10:19 Thanks, uh, to both of you and, uh, hello,
00:10:19 --> 00:10:22 tr. All is well at school. I
00:10:22 --> 00:10:24 don't know if you like school or loathe it.
00:10:24 --> 00:10:26 Uh, I was not
00:10:27 --> 00:10:30 a very motivated student when I went
00:10:30 --> 00:10:32 to school. I think I did most of my learning
00:10:32 --> 00:10:35 when I got out, um, after they
00:10:35 --> 00:10:37 unlocked the doors. But anyway, um,
00:10:38 --> 00:10:40 Tristan's got a good question. We've had
00:10:40 --> 00:10:42 black hole, white hole questions a few times
00:10:42 --> 00:10:45 in the past. Uh, and it
00:10:45 --> 00:10:47 is probably logical to
00:10:47 --> 00:10:50 say that the theory is it would be quite the
00:10:50 --> 00:10:52 opposite. That's the reason it's called a
00:10:52 --> 00:10:55 white hole, I think, or they think
00:10:55 --> 00:10:57 it's white? I don't know, Fred Watson.
00:10:58 --> 00:10:58 Professor Fred Watson: We haven't
00:10:58 --> 00:10:59 Andrew Dunkley: found one yet.
00:10:59 --> 00:11:02 Professor Fred Watson: No, we haven't. Uh, so they are a
00:11:02 --> 00:11:04 theoretical entity,
00:11:05 --> 00:11:07 uh, and they are mathematically the
00:11:07 --> 00:11:10 opposite of a black hole, uh,
00:11:10 --> 00:11:13 in terms of some of the
00:11:13 --> 00:11:14 aspects, um,
00:11:16 --> 00:11:18 particularly in terms of something called
00:11:18 --> 00:11:20 time reversal. A, uh, comment
00:11:21 --> 00:11:23 that I've seen is if you played a video of a
00:11:23 --> 00:11:25 black hole backwards, it would look like a
00:11:25 --> 00:11:27 white hole. Um,
00:11:28 --> 00:11:31 that we. Yeah,
00:11:31 --> 00:11:34 we don't. To be honest, most physicists don't
00:11:34 --> 00:11:36 believe that they exist, uh,
00:11:36 --> 00:11:39 that, um, they're not real. But just
00:11:39 --> 00:11:42 going to the question that Tristan has posed,
00:11:42 --> 00:11:44 um, black holes of extremely high gravity
00:11:45 --> 00:11:47 are, uh, white holes the opposite? Uh, and
00:11:47 --> 00:11:50 the answer is, no, they're not.
00:11:52 --> 00:11:55 They still have a gravitational field because
00:11:55 --> 00:11:57 they've got mass. Uh,
00:11:58 --> 00:12:00 it's, you know, that doesn't go in the time
00:12:00 --> 00:12:03 reversal, doesn't affect that. But
00:12:03 --> 00:12:06 so the main thing is it doesn't have negative
00:12:06 --> 00:12:07 gravity, which is what you might think,
00:12:07 --> 00:12:09 because it's the opposite of a black hole in
00:12:09 --> 00:12:12 every other way. But it's not the.
00:12:12 --> 00:12:15 Not the fact that its mass becomes
00:12:15 --> 00:12:17 negative. It's the way
00:12:18 --> 00:12:21 space time behaves around it.
00:12:22 --> 00:12:24 Um, that's the crucial thing that makes
00:12:24 --> 00:12:27 it, uh, a white hole where it's trying to
00:12:27 --> 00:12:30 push everything outwards rather than pull
00:12:30 --> 00:12:31 everything inwards, which is what a black
00:12:31 --> 00:12:34 hole is doing. So it's all. Is a geometrical
00:12:34 --> 00:12:37 point. And I should just highlight here that
00:12:37 --> 00:12:39 the hall of Relativity is built on geometry.
00:12:40 --> 00:12:42 Uh, it's a geometrical theory.
00:12:42 --> 00:12:45 Um, Um, I did a talk on it a couple of
00:12:45 --> 00:12:47 weeks ago, and I actually took the equations
00:12:47 --> 00:12:49 out of it just because I didn't want to bore
00:12:49 --> 00:12:51 everybody to death. But the equations of
00:12:51 --> 00:12:53 relativity are basically geometry. In, uh,
00:12:53 --> 00:12:55 fact, in a sense, it's all Pythagoras's
00:12:55 --> 00:12:57 theorem, but it's very highly modified.
00:12:58 --> 00:13:00 Um, and so the geometry of the space time
00:13:00 --> 00:13:02 around the white hole is what makes
00:13:02 --> 00:13:04 everything want to get pushed out, rather
00:13:04 --> 00:13:06 than it having negative mass.
00:13:08 --> 00:13:10 Andrew Dunkley: Okay, yes, I understand. Um,
00:13:12 --> 00:13:15 I was just doing an AI Search on that very
00:13:15 --> 00:13:16 thing, and it says white holes are
00:13:16 --> 00:13:18 mathematically possible under Einstein's
00:13:18 --> 00:13:20 general theory of relativity, but physically
00:13:21 --> 00:13:23 unproven and unlikely to exist in our, uh,
00:13:23 --> 00:13:24 universe.
00:13:25 --> 00:13:26 Professor Fred Watson: I think I said something very similar to
00:13:26 --> 00:13:27 that. You
00:13:27 --> 00:13:29 Andrew Dunkley: did. I just wanted to
00:13:29 --> 00:13:31 compare to Einstein.
00:13:31 --> 00:13:33 Professor Fred Watson: M. Me and A.I. uh, were like that.
00:13:33 --> 00:13:36 Andrew Dunkley: Yeah, it's got its positives,
00:13:36 --> 00:13:37 but it's certainly getting some bad press
00:13:37 --> 00:13:38 too. Yeah, it
00:13:38 --> 00:13:40 Professor Fred Watson: is. Yes, it is indeed.
00:13:40 --> 00:13:42 Andrew Dunkley: Uh, I learned a new, um, online word.
00:13:42 --> 00:13:45 It's not A new word, but it's a new use
00:13:45 --> 00:13:48 for the word. It's. It's called slop. You
00:13:48 --> 00:13:49 know what slop means?
00:13:50 --> 00:13:53 Professor Fred Watson: Um, it's. Yes, it's the. The sort of.
00:13:54 --> 00:13:56 It's AI that's not got things quite right.
00:13:56 --> 00:13:57 Yeah, right.
00:13:58 --> 00:14:00 Andrew Dunkley: Sort of. It's. It's where an entire
00:14:00 --> 00:14:03 paper book article, whatever
00:14:03 --> 00:14:06 has been AI Generated absolutely no
00:14:06 --> 00:14:08 human creation in it at all.
00:14:09 --> 00:14:11 And unfortunately, it's starting to happen
00:14:11 --> 00:14:14 more and more and more. It's
00:14:14 --> 00:14:17 nasty stuff. Uh, and white holes are slop
00:14:17 --> 00:14:20 as well. No, we don't know that. Um, but
00:14:21 --> 00:14:23 we do know black holes
00:14:23 --> 00:14:26 exist. We don't know if white holes
00:14:26 --> 00:14:28 exist. They probably don't. But, uh, they
00:14:28 --> 00:14:31 would not be the exact opposite of a black
00:14:31 --> 00:14:32 hole is what we're saying.
00:14:32 --> 00:14:35 Professor Fred Watson: Yeah, that's right. In that regard. Um, it's
00:14:35 --> 00:14:37 what they do to space time that changes the.
00:14:37 --> 00:14:38 Basically changes
00:14:40 --> 00:14:42 the nature of the thing into something that's
00:14:42 --> 00:14:45 the opposite of a black hole. But. Great
00:14:45 --> 00:14:48 question, Tristan. And one, I'm absolutely
00:14:48 --> 00:14:51 delighted, um, you asked because it gave
00:14:51 --> 00:14:53 me a chance to think all that stuff through
00:14:53 --> 00:14:55 and bring back some memories of what I
00:14:55 --> 00:14:56 learned a few years ago.
00:14:56 --> 00:14:59 Andrew Dunkley: Very good. Uh, thanks, Tristan. Thanks,
00:14:59 --> 00:15:02 Simon. And keep, uh, the curiosity coming. We
00:15:02 --> 00:15:04 love hearing from, uh, the younger audience
00:15:04 --> 00:15:07 members here on Space Nuts. You're with
00:15:07 --> 00:15:09 Andrew Dunkley and Professor Fred Watson
00:15:09 --> 00:15:09 Watson.
00:15:11 --> 00:15:13 John F. Kennedy: I believe that this nation should commit
00:15:13 --> 00:15:15 itself to achieving the goal,
00:15:16 --> 00:15:19 before this decade is out, of landing a
00:15:19 --> 00:15:21 man on the moon and returning him safely to
00:15:21 --> 00:15:23 the Earth. Space Nuts,
00:15:24 --> 00:15:26 Andrew Dunkley: our, uh, next question, Fred Watson, is
00:15:27 --> 00:15:28 massive.
00:15:28 --> 00:15:31 Mike (from Hayward, California): Hey, Space Nuts, this is Mike in Hayward,
00:15:31 --> 00:15:34 California. Got a question for you about
00:15:34 --> 00:15:36 dark matter. Big surprise. So I've been
00:15:36 --> 00:15:39 thinking about dark, um, matter. And
00:15:39 --> 00:15:41 the way that you've described it on the
00:15:41 --> 00:15:44 podcast is it seems to
00:15:44 --> 00:15:47 be the solution to the problem that
00:15:47 --> 00:15:49 astronomers observe when they look at
00:15:49 --> 00:15:52 galaxies and they see the rate at
00:15:52 --> 00:15:55 which they're spinning doesn't quite line
00:15:55 --> 00:15:57 up with the mass that they can
00:15:57 --> 00:16:00 calculate of the galaxy that it seems like
00:16:00 --> 00:16:03 the stars should be flying off into space.
00:16:04 --> 00:16:06 Uh, except that they're not. So there must be
00:16:07 --> 00:16:10 more matter there that is causing
00:16:10 --> 00:16:12 a gravitational force to keep
00:16:12 --> 00:16:15 them in place. So I've been thinking
00:16:15 --> 00:16:18 about, um, are there other ways to
00:16:18 --> 00:16:21 measure this more locally? And I was
00:16:21 --> 00:16:24 thinking about the Earth. And we can make a
00:16:24 --> 00:16:27 direct, accurate measurement of the Earth's
00:16:27 --> 00:16:30 gravity, but we can't really make a direct
00:16:30 --> 00:16:32 measurement of the Earth's mass. Uh,
00:16:32 --> 00:16:35 so my question is, is the Earth's
00:16:35 --> 00:16:38 mass, uh, over overestimated?
00:16:39 --> 00:16:41 Because there's a component of the gravity
00:16:41 --> 00:16:44 that we feel that is attributable to dark
00:16:44 --> 00:16:46 matter and not all of it is
00:16:47 --> 00:16:49 baryonic matter. Anyway, hope that
00:16:49 --> 00:16:52 makes sense. Love your podcast. Can't wait to
00:16:52 --> 00:16:53 hear the answer. Thanks, guys.
00:16:54 --> 00:16:55 Andrew Dunkley: Thank you, Mike. Oh, you put a lot of thought
00:16:55 --> 00:16:58 into that. Um,
00:16:59 --> 00:17:01 uh, uh, um, it's a difficult question
00:17:01 --> 00:17:04 to get your head around. Um, so
00:17:04 --> 00:17:05 over to you, Fred Watson.
00:17:08 --> 00:17:08 Professor Fred Watson: I
00:17:08 --> 00:17:10 Andrew Dunkley: was going to paraphrase what he was asking,
00:17:10 --> 00:17:12 but it's just gone straight in one ear out
00:17:12 --> 00:17:12 the other,
00:17:13 --> 00:17:15 Professor Fred Watson: so. Yes, um, so,
00:17:17 --> 00:17:19 well, um, Mike's point
00:17:20 --> 00:17:23 was that we can measure gravity
00:17:23 --> 00:17:26 on Earth, uh, more accurately that
00:17:26 --> 00:17:28 we can than we can measure its mass. Um, I
00:17:28 --> 00:17:30 don't think that's true. The mass of the
00:17:30 --> 00:17:33 Earth is very well determined and it comes
00:17:33 --> 00:17:35 actually from space observations. You can
00:17:36 --> 00:17:38 just looking at the dynamics of the solar
00:17:38 --> 00:17:41 system, the way the planet moves in its orbit
00:17:41 --> 00:17:42 around the sun and the way it interacts with
00:17:42 --> 00:17:45 the other planets, we know it's mass to a
00:17:45 --> 00:17:47 very high accuracy. Um,
00:17:48 --> 00:17:50 and so that's
00:17:51 --> 00:17:53 not something we can compare.
00:17:55 --> 00:17:58 So we know its mass. The
00:17:58 --> 00:18:00 gravitational pull as, ah, a result of that,
00:18:00 --> 00:18:03 which we can also measure, uh, is
00:18:03 --> 00:18:06 completely consistent with its mass. So, um,
00:18:06 --> 00:18:08 I think what Mike is asking is if you measure
00:18:08 --> 00:18:10 the mass of the Earth and you measure its
00:18:10 --> 00:18:13 gravitational pull, uh, is there
00:18:14 --> 00:18:16 a component of that gravitational pull that's
00:18:16 --> 00:18:18 not due to the Earth, it's due to dark
00:18:18 --> 00:18:21 matter. Ah. And the answer
00:18:21 --> 00:18:22 is no, because
00:18:24 --> 00:18:26 we on Earth are immersed in a
00:18:26 --> 00:18:29 blob of dark matter, which certainly has
00:18:29 --> 00:18:32 gravitational pull, but it's going in
00:18:32 --> 00:18:34 all directions and so we don't feel
00:18:34 --> 00:18:37 its effect. It
00:18:37 --> 00:18:40 just cancels out. It's pulling in all
00:18:40 --> 00:18:41 directions because blobs of dark matter. Uh,
00:18:42 --> 00:18:43 uh,
00:18:46 --> 00:18:48 um. Did you hear that?
00:18:49 --> 00:18:50 Andrew Dunkley: That sounds like a dark matter.
00:18:51 --> 00:18:54 Professor Fred Watson: It was, it was, um, it was me,
00:18:54 --> 00:18:57 uh, tripping over a cable underneath my desk,
00:18:57 --> 00:19:00 which pulled all this stuff attached to it
00:19:00 --> 00:19:02 down onto the, oh, onto the floor.
00:19:04 --> 00:19:06 Andrew Dunkley: That's the good news. And I can still hear
00:19:06 --> 00:19:06 you.
00:19:06 --> 00:19:08 Professor Fred Watson: Yeah, no, it's all right. It's not done any
00:19:08 --> 00:19:11 harm. My table lamp is lying
00:19:11 --> 00:19:13 pointing awkwardly upwards rather than
00:19:13 --> 00:19:15 downwards like it's supposed to be. But
00:19:15 --> 00:19:17 everything will be fine. I'm not really
00:19:17 --> 00:19:20 worried about that. Um,
00:19:20 --> 00:19:23 so, um, yeah, so dark matter,
00:19:23 --> 00:19:26 basically what you can, you know, if you
00:19:26 --> 00:19:28 imagine the Earth, uh, there it is trundling
00:19:28 --> 00:19:30 around in its orbit, but it's
00:19:30 --> 00:19:33 immersed in a blob of dark matter which is
00:19:33 --> 00:19:36 probably much bigger than the whole galaxy.
00:19:36 --> 00:19:39 And so the density of
00:19:39 --> 00:19:42 that dark matter is effectively the same
00:19:42 --> 00:19:44 everywhere. As far as the Earth's concerned,
00:19:44 --> 00:19:44 Andrew Dunkley: uh,
00:19:44 --> 00:19:47 Professor Fred Watson: and so it's pulling in all directions. You
00:19:47 --> 00:19:49 can just take it completely out of the
00:19:49 --> 00:19:51 equations of motions of a planet.
00:19:52 --> 00:19:55 Andrew Dunkley: Okay, so would the dark matter be
00:19:55 --> 00:19:57 moving with the Earth and with the galaxy, or
00:19:57 --> 00:19:59 are we passing through it?
00:20:00 --> 00:20:03 Professor Fred Watson: Uh, um, there probably isn't a
00:20:03 --> 00:20:06 relative velocity between us and dark matter.
00:20:06 --> 00:20:08 Although there is an experiment
00:20:08 --> 00:20:11 that's being done in Gran Sasso in
00:20:11 --> 00:20:14 Italy that suggests that we are moving
00:20:14 --> 00:20:16 through dark matter because they think they
00:20:16 --> 00:20:18 see a different signature of
00:20:18 --> 00:20:20 certain. I think it's gamma radiation that
00:20:20 --> 00:20:23 they're picking up, uh, when the Earth is on
00:20:23 --> 00:20:25 one side of its orbit from when it's on the
00:20:25 --> 00:20:28 other side. Uh, but more or less,
00:20:28 --> 00:20:30 you can imagine that the blob of dark matter
00:20:30 --> 00:20:33 is rotating with the galaxy. That's
00:20:33 --> 00:20:34 very roughly.
00:20:34 --> 00:20:37 Andrew Dunkley: Okay, so what was the answer to Mike's
00:20:37 --> 00:20:37 question?
00:20:38 --> 00:20:39 Professor Fred Watson: No,
00:20:39 --> 00:20:42 Andrew Dunkley: no, I love it when
00:20:42 --> 00:20:43 it's that simple.
00:20:43 --> 00:20:45 Professor Fred Watson: Yeah, I can't remember what the question was.
00:20:45 --> 00:20:48 Let me just have a quick look to remind me.
00:20:48 --> 00:20:51 Uh, actually, no, it's an audio question,
00:20:51 --> 00:20:52 so I can't.
00:20:52 --> 00:20:53 Andrew Dunkley: Yeah, yeah. Um.
00:20:53 --> 00:20:55 Professor Fred Watson: Uh, but yes,
00:20:57 --> 00:21:00 I, uh, like the idea of, you know, taking.
00:21:01 --> 00:21:03 Measuring the Earth's gravity, measuring its
00:21:03 --> 00:21:06 mass, and from its mass you work out
00:21:06 --> 00:21:07 how much gravity it should have. Uh, and then
00:21:07 --> 00:21:10 you compare the two, the measurement of the
00:21:10 --> 00:21:12 gravity, with the theoretical prediction, but
00:21:12 --> 00:21:14 they're exactly the same. And that's because
00:21:14 --> 00:21:17 the dark matter's gravity cancels out,
00:21:17 --> 00:21:17 basically.
00:21:17 --> 00:21:19 Andrew Dunkley: Well, here's a test for you, Fred Watson.
00:21:20 --> 00:21:21 What is the mass of the Earth?
00:21:22 --> 00:21:25 Professor Fred Watson: Um, it's about. It's a few tons,
00:21:25 --> 00:21:26 isn't it? Um, it's
00:21:26 --> 00:21:27 Andrew Dunkley: a couple of kilogrammes.
00:21:28 --> 00:21:30 Professor Fred Watson: Yeah. The number, I think the sun's mass
00:21:31 --> 00:21:33 is 10 to
00:21:33 --> 00:21:36 27 kilogrammes. Is that
00:21:36 --> 00:21:38 right or is that tonnes? I can't remember,
00:21:38 --> 00:21:39 Andrew Dunkley: but
00:21:39 --> 00:21:42 Professor Fred Watson: it's a number with a, uh, lot of zeros
00:21:42 --> 00:21:42 after it.
00:21:42 --> 00:21:42 Andrew Dunkley: Yeah.
00:21:42 --> 00:21:44 Professor Fred Watson: What is the mass of the earth? You tell me.
00:21:44 --> 00:21:46 Andrew Dunkley: 52 times 10 to the
00:21:46 --> 00:21:48 24th kilogrammes, or
00:21:49 --> 00:21:52 5.97 sextillion kilogrammes.
00:21:53 --> 00:21:53 Professor Fred Watson: Yep.
00:21:53 --> 00:21:55 Andrew Dunkley: I don't know what that is in pounds. Sorry,
00:21:55 --> 00:21:57 America, I apologise.
00:21:58 --> 00:22:00 Professor Fred Watson: Yeah. What is it in dollars? That's the
00:22:00 --> 00:22:00 thing. That's
00:22:00 --> 00:22:03 Andrew Dunkley: a good question. I wonder if AI can
00:22:03 --> 00:22:04 answer that.
00:22:05 --> 00:22:07 Professor Fred Watson: Uh, what is the mass of the Earth in dollars?
00:22:07 --> 00:22:08 I bet it can.
00:22:09 --> 00:22:11 Andrew Dunkley: I'll do it in US dollars, because, you know,
00:22:11 --> 00:22:14 Australian dollars, it'll just say 10 bucks.
00:22:18 --> 00:22:20 Oh, dear. Yeah,
00:22:21 --> 00:22:23 I want to feel with a number.
00:22:24 --> 00:22:26 Professor Fred Watson: It might, uh. I think AI, uh. Is it
00:22:26 --> 00:22:29 Andrew Dunkley: did. 5 quadrillion US dollars.
00:22:29 --> 00:22:31 Professor Fred Watson: That's what it's
00:22:31 --> 00:22:31 Andrew Dunkley: worth.
00:22:31 --> 00:22:32 Professor Fred Watson: I thought
00:22:32 --> 00:22:33 Andrew Dunkley: Elon Musk had that much money
00:22:35 --> 00:22:37 Professor Fred Watson: anyway. There you go,
00:22:38 --> 00:22:39 Andrew Dunkley: M. Nobody
00:22:39 --> 00:22:40 Professor Fred Watson: can say we're not adequate with. No,
00:22:41 --> 00:22:42 Andrew Dunkley: very thorough when it comes to money.
00:22:44 --> 00:22:46 Well, some people are. I haven't got any. All
00:22:46 --> 00:22:48 right, thanks, Mike. Thanks for the question.
00:22:48 --> 00:22:51 Hope we adequately covered it for you.
00:22:52 --> 00:22:54 Suspect not, but anyway, we'll um, we might
00:22:54 --> 00:22:55 do a sequel. One day.
00:22:59 --> 00:23:01 Professor Fred Watson: Three, two, one.
00:23:02 --> 00:23:03 Space Nuts.
00:23:03 --> 00:23:05 Andrew Dunkley: Our final question on space nuts today,
00:23:05 --> 00:23:08 Fred Watson, comes from Eduardo, who is
00:23:08 --> 00:23:11 from Gran Canaria in the Canary Islands.
00:23:11 --> 00:23:14 Lovely. Um, we drove past there
00:23:14 --> 00:23:17 last year in a ship. We got to wave.
00:23:17 --> 00:23:19 We were supposed to stop there, but um, the
00:23:19 --> 00:23:21 schedule changed so we ended up um,
00:23:22 --> 00:23:25 at um, uh, Tenerife instead.
00:23:26 --> 00:23:28 Uh, so Eduardo, uh, asked do neutrinos
00:23:28 --> 00:23:30 interact with gravity at all? Do they get
00:23:30 --> 00:23:32 swallowed by black holes or do they just
00:23:32 --> 00:23:35 shoot through them like ordinary matter?
00:23:36 --> 00:23:38 Uh, light is massless, moves at the speed of
00:23:38 --> 00:23:40 light, and yet can't shoot through the Earth
00:23:40 --> 00:23:43 like neutrinos do, hardly interacting with
00:23:43 --> 00:23:45 matter at all. Although I imagine it would be
00:23:45 --> 00:23:48 hard even for neutrinos to shoot through a
00:23:48 --> 00:23:51 point of infinite density. I
00:23:51 --> 00:23:53 suppose that point, the so called
00:23:53 --> 00:23:56 singularity, is all the way, uh,
00:23:56 --> 00:23:58 down the gravity well of a black hole.
00:23:59 --> 00:24:01 Not all of the black hole volume from the
00:24:01 --> 00:24:04 event horizon to the
00:24:04 --> 00:24:07 singularity has infinite, uh, density,
00:24:07 --> 00:24:09 I guess. Or does it? What about
00:24:09 --> 00:24:12 spacetime itself? Bodies with huge mass and
00:24:12 --> 00:24:15 gravitational influence bend spacetime. They
00:24:15 --> 00:24:17 can also make an vibrate, generating
00:24:17 --> 00:24:20 gravitational waves if the interaction is
00:24:20 --> 00:24:22 strong enough, making space time somewhat of
00:24:22 --> 00:24:25 a material in nature. Could huge
00:24:25 --> 00:24:28 supermassive black holes feed on space time
00:24:28 --> 00:24:30 itself? Thanks for your answers, Eduardo.
00:24:31 --> 00:24:32 Thought provoking.
00:24:33 --> 00:24:36 Professor Fred Watson: It is, yeah. Um, I also
00:24:36 --> 00:24:38 have visited Gran Canaria,
00:24:40 --> 00:24:43 um, many times, um, usually
00:24:43 --> 00:24:45 on my way to La Palma where I used to observe
00:24:45 --> 00:24:47 a lot on the, um, William Herschel
00:24:47 --> 00:24:49 Telescope on the island of La Palma.
00:24:49 --> 00:24:50 Andrew Dunkley: Yeah,
00:24:50 --> 00:24:52 Professor Fred Watson: uh, it's a lovely part of the world. Uh,
00:24:53 --> 00:24:56 my last trip there was kind of
00:24:56 --> 00:24:59 disappointing because, um, Nani was supposed
00:24:59 --> 00:25:01 to come with me, but for reasons beyond our
00:25:01 --> 00:25:03 control she couldn't. So I ended up there on
00:25:03 --> 00:25:05 my own, doing a conference. Anyway, that's a
00:25:05 --> 00:25:08 long story. Um,
00:25:08 --> 00:25:11 um, okay, uh, so the
00:25:11 --> 00:25:14 basic question, uh, is let
00:25:14 --> 00:25:16 me just read the question. Do, in, do
00:25:16 --> 00:25:19 neutrinos interact with gravity at all?
00:25:20 --> 00:25:22 And the answer is yes. Um,
00:25:22 --> 00:25:25 because they've got a, um, non zero
00:25:25 --> 00:25:28 rest mass. Unlike a photon, which
00:25:28 --> 00:25:30 has zero rest mass. Um,
00:25:31 --> 00:25:34 a neutrino has a non zero rest
00:25:34 --> 00:25:37 mass but is Very, very small. But
00:25:37 --> 00:25:39 nevertheless, uh, that is enough to mean that
00:25:39 --> 00:25:42 it follows the curvature of space time.
00:25:42 --> 00:25:45 Exactly as defined by general relativity.
00:25:45 --> 00:25:47 So they do interact with grav.
00:25:48 --> 00:25:51 Um, and, you know,
00:25:51 --> 00:25:54 that's basically the crucial point about all
00:25:54 --> 00:25:56 this. Uh, if a neutrino
00:25:57 --> 00:25:59 crosses the event
00:26:01 --> 00:26:03 horizon of a black hole, uh,
00:26:04 --> 00:26:07 um, they do get swallowed, um,
00:26:08 --> 00:26:10 by a black hole. Uh,
00:26:11 --> 00:26:14 so it's the ones
00:26:14 --> 00:26:17 that are probably moving quickly enough that
00:26:17 --> 00:26:20 avoid being swallowed. But because they've
00:26:20 --> 00:26:22 got mass, and black holes love eating
00:26:22 --> 00:26:25 mass, that means they just basically get
00:26:25 --> 00:26:26 swallowed. Generally,
00:26:26 --> 00:26:28 Andrew Dunkley: they wouldn't get much out of a neutrino.
00:26:28 --> 00:26:30 Professor Fred Watson: No, that's not right. They're certainly not
00:26:31 --> 00:26:33 sustained by a neutrino in terms of
00:26:33 --> 00:26:36 sustenance. Um, so, yes,
00:26:36 --> 00:26:39 that's basically the question that, um,
00:26:39 --> 00:26:41 they do get swallowed. They don't. They don't
00:26:41 --> 00:26:43 just shoot through, uh,
00:26:43 --> 00:26:45 them, you know, like.
00:26:46 --> 00:26:49 Well, like nothing does really. And yet
00:26:49 --> 00:26:50 Andrew Dunkley: they can pass through Earth.
00:26:52 --> 00:26:55 Professor Fred Watson: Yeah, but that's because their mass and
00:26:55 --> 00:26:57 their, you know, their interact. If I can put
00:26:57 --> 00:26:59 it this way, their interactability with
00:26:59 --> 00:27:02 other, uh, subatomic particles is so
00:27:02 --> 00:27:04 low, they're weakly interacting. Very, very
00:27:04 --> 00:27:07 weakly interacting. So they just zoom through
00:27:07 --> 00:27:09 the Earth, Uh, uh, but they
00:27:09 --> 00:27:12 still have mass, um, but only a
00:27:12 --> 00:27:15 tiny amount. And so they will be sucked into
00:27:15 --> 00:27:16 a black hole.
00:27:17 --> 00:27:18 Andrew Dunkley: Uh, and that was the second part of his
00:27:18 --> 00:27:21 question. Ah. And the crux of that was,
00:27:22 --> 00:27:24 could a supermassive black hole feed on
00:27:24 --> 00:27:25 spacetime itself?
00:27:26 --> 00:27:29 Professor Fred Watson: Um, I don't think so, because
00:27:30 --> 00:27:32 space, ah, time is,
00:27:33 --> 00:27:36 you know, I mean, essentially
00:27:36 --> 00:27:39 Eduardo's suggesting that spacetime
00:27:39 --> 00:27:42 is material real in nature, but it's
00:27:42 --> 00:27:44 not. It's the medium, if I can put it that
00:27:44 --> 00:27:46 way. It's not a medium. It's just a framework
00:27:46 --> 00:27:49 within which everything else sits. Uh,
00:27:49 --> 00:27:51 so, um, a, uh, black hole feeding on m
00:27:51 --> 00:27:54 space time, I think, will be out of the
00:27:54 --> 00:27:55 question. There's plenty of other stuff
00:27:55 --> 00:27:57 within that space time for it to feed on,
00:27:57 --> 00:28:00 which is material in nature. Uh, uh, but
00:28:00 --> 00:28:01 not space time itself.
00:28:02 --> 00:28:05 Andrew Dunkley: Yeah. Okay, very good.
00:28:05 --> 00:28:06 I think we covered it.
00:28:07 --> 00:28:08 Professor Fred Watson: Um, I hope so.
00:28:11 --> 00:28:14 Andrew Dunkley: All right. Uh, thank you, Eduardo. Um, thanks
00:28:14 --> 00:28:16 for sending the question in. And a reminder.
00:28:16 --> 00:28:18 If you'd like to send us questions, please do
00:28:18 --> 00:28:19 just go to our website,
00:28:20 --> 00:28:22 spacenutspodcast.com or
00:28:22 --> 00:28:25 spacenuts IO. There's a little link at the
00:28:25 --> 00:28:28 top called AMA Ask Me Anything. You
00:28:28 --> 00:28:30 click on that and you can send us text or
00:28:30 --> 00:28:32 audio questions. Just, uh, fill in the
00:28:32 --> 00:28:34 blanks. Uh, if you've got a device, a smart
00:28:34 --> 00:28:36 device with a microphone, you're all Set.
00:28:36 --> 00:28:38 Just don't forget to tell us who you are and
00:28:38 --> 00:28:40 where you're from. We just like to know so we
00:28:40 --> 00:28:41 can spam you.
00:28:43 --> 00:28:45 I wish that was not true, but I have actually
00:28:46 --> 00:28:49 spammed a couple of people lately with, you
00:28:49 --> 00:28:51 know, some book that I was trying to flog.
00:28:52 --> 00:28:55 Yeah. Um, and thanks for those who have
00:28:55 --> 00:28:58 actually bought it. And even bigger thanks to
00:28:58 --> 00:29:00 those who've read it. I appreciate that.
00:29:00 --> 00:29:03 Um, because I've gone, um, I've gone Kindle
00:29:03 --> 00:29:06 plus on it, Fred Watson. And, uh, it gives
00:29:06 --> 00:29:08 me a report every day of how many pages have
00:29:08 --> 00:29:11 been read, which is fascinating because I
00:29:11 --> 00:29:12 get paid per page.
00:29:13 --> 00:29:15 Professor Fred Watson: Okay, that's interesting. Per page read.
00:29:15 --> 00:29:18 Andrew Dunkley: Yeah. So you get, you get, um,
00:29:18 --> 00:29:21 so many cents per page. I earned five cents
00:29:21 --> 00:29:23 yesterday after tax.
00:29:23 --> 00:29:25 That'll be one and a half cents.
00:29:26 --> 00:29:29 Professor Fred Watson: It's not, um, really comparable with the mass
00:29:29 --> 00:29:30 of the earth in dollars, is it? No,
00:29:30 --> 00:29:32 Andrew Dunkley: not really, no.
00:29:33 --> 00:29:35 Yeah, I never thought of it that way. But
00:29:35 --> 00:29:38 any, uh, it's just fun to do it. I
00:29:38 --> 00:29:40 enjoy writing and I enjoy the. I don't really
00:29:40 --> 00:29:42 enjoy the marketing side of things. That's
00:29:42 --> 00:29:43 not my jam.
00:29:45 --> 00:29:46 Professor Fred Watson: That's right.
00:29:47 --> 00:29:50 Andrew Dunkley: Anyway, uh, so, yes, keep those cards
00:29:50 --> 00:29:52 and letters coming in. Love to hear from you.
00:29:52 --> 00:29:55 And thank, uh, you, Fred Watson, as always,
00:29:55 --> 00:29:57 for answering those questions so thoroughly.
00:29:58 --> 00:30:01 Professor Fred Watson: Well, thank you, Andrew. Yeah, I am, um,
00:30:01 --> 00:30:02 glad you think they were thoroughly answered.
00:30:02 --> 00:30:03 That's all right. Um,
00:30:04 --> 00:30:04 Andrew Dunkley: or adequately.
00:30:07 --> 00:30:09 Professor Fred Watson: I'll. I'll take that one, thank you. Fair
00:30:09 --> 00:30:10 Andrew Dunkley: enough. We'll see. We'll see you soon,
00:30:10 --> 00:30:11 Fred Watson. Thank you. Yeah,
00:30:11 --> 00:30:12 Professor Fred Watson: uh, cheers for now. Bye.
00:30:12 --> 00:30:12 Bye.
00:30:12 --> 00:30:14 Andrew Dunkley: Professor Fred Watson Watson, astronomer at
00:30:14 --> 00:30:17 large, and thanks to Huw in this studio, uh,
00:30:17 --> 00:30:18 couldn't be with us today because he
00:30:18 --> 00:30:21 underestimated his mass and he's had to go to
00:30:21 --> 00:30:24 the gym. And from me, Andrew Dunkley,
00:30:24 --> 00:30:25 uh, we'll see you on the next episode of
00:30:25 --> 00:30:27 Space Nuts. Until then, bye Bye.
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