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Cosmic Questions: Dark Energy, Stellar Birth & the Nature of Black Holes · Space Nuts: Astronomy Insights & Cosmic Discoveries

0:00
Speaker 1: Hi there, Thanks for joining us. My name is Andrew
0:03
Speaker 1: Dunkley and this is Space Nuts, a Q and A edition.
0:06
Speaker 1: It also happens to be our sixth hundredth episode Believe
0:11
Speaker 1: it or not. And what are we doing special today? Nothing.
0:14
Speaker 1: We're just going to answer audience and well it happens
0:17
Speaker 1: so often. Now we're just going to answer audience questions
0:21
Speaker 1: and we've got a bunch of them. The question of
0:24
Speaker 1: dark matter and dark energy theory has come up again.
0:28
Speaker 1: In fact, one of our listeners has come up with
0:30
Speaker 1: a theory about dark matter and dark energy theory, so
0:33
Speaker 1: we'll investigate that. We also have a question from somebody
0:37
Speaker 1: using a very interesting pseudonym finding where our son was born.
0:43
Speaker 1: I think we've been down that road before recently. So
0:46
Speaker 1: they're revisiting that the temperature of black holes has been
0:50
Speaker 1: raised yet again. We talked about that recently, and Peter
0:54
Speaker 1: has asked us about the expansion of the universe. That's
0:58
Speaker 1: all coming up on this edition of Space Nuts.
1:01
Speaker 2: Fifteen, Channel ten nine, Ignition thig one start Space Nuts
1:09
Speaker 2: nine or three two more Radio one Space notes asn't
1:15
Speaker 2: actually bought it.
1:16
Speaker 1: Bill's good once again joining us from the Oh It's
1:20
Speaker 1: not the six hundred time because we've had time off,
1:23
Speaker 1: so it's probably five hundred and ninety two or something
1:27
Speaker 1: like that. Maybe I don't know, maybe a few less.
1:29
Speaker 1: But his name is Fred Watson, Professor Fred Watson, in
1:32
Speaker 1: fact astronomer at large HIO. Fred. How you doing, Andrew?
1:36
Speaker 1: I'm google see you again. Good to see you too.
1:39
Speaker 1: Can you believe it's six hundred episodes? My goodness?
1:42
Speaker 3: So we because we know have two a week. Ye,
1:45
Speaker 3: you've got through one hundred every year, basically, doesn't it?
1:47
Speaker 3: Mora where it used to be every couple of years. So, yes,
1:53
Speaker 3: we're just moving faster. It's the expansion of the universe
1:56
Speaker 3: because it's accelerating. That's a little it is relive relativistic.
2:00
Speaker 1: Indeed, let us get straight into our questions because we've
2:05
Speaker 1: got a whole bunch of them. Daryl has set us
2:08
Speaker 1: in a question today space and that's I've been giving
2:10
Speaker 1: dark energy and dark matter some thought. If I've got
2:14
Speaker 1: this rise, dark matter pushes the universe apart or away,
2:19
Speaker 1: while dark energy attracts or brings stuff together. So could
2:24
Speaker 1: dark matter and dark energy be the same thing, but
2:27
Speaker 1: have like a north and south pole, I e. Dark
2:31
Speaker 1: matter north would be the particle that clumps together, and
2:34
Speaker 1: dark energy south would be the particle that pushes outwards,
2:38
Speaker 1: creating negative pressure and expanding the universe. Thoughts, now that's
2:42
Speaker 1: his question, But he says, by the way, Martin's joke
2:45
Speaker 1: about the Ganab Gibb being a lost bg brother made
2:49
Speaker 1: me laugh out loud for a couple of minutes. That's
2:52
Speaker 1: Daryl from South Australia. Yeah, I thought it was funny too,
2:55
Speaker 1: and that's the first time Martin's ever been funny. But no,
2:59
Speaker 1: it was a good that was a very good one. Yes,
3:03
Speaker 1: so this is an interesting theory as a dark matter,
3:06
Speaker 1: say Powell, dark energy North Powell opposite attract type of scenario.
3:12
Speaker 1: I don't know what do you think.
3:14
Speaker 3: So the issue, Yes, it's a nice thought because that
3:19
Speaker 3: you know, we naturally think along those lines when we
3:22
Speaker 3: recognize that one of these forces entities pull stuff together
3:29
Speaker 3: and the other pushes it apart. And in many ways
3:37
Speaker 3: that's the crux of the matter, because the two of
3:39
Speaker 3: them are fundamentally different in their in their effect on
3:45
Speaker 3: the universe. So dark energy, which comes as a man
3:50
Speaker 3: which is manifested to us in the accelerated expansion of
3:54
Speaker 3: the universe. That's an energy of space itself, and to
3:58
Speaker 3: the best of our ability to determine these things, it
4:02
Speaker 3: is isotropic. In other words, it's the same in all directions. Now,
4:07
Speaker 3: some people have questioned that, suggesting that maybe you know,
4:13
Speaker 3: for all, we are looking at a big chunk of
4:15
Speaker 3: the universe with a horizon of thirteen point eight billion
4:18
Speaker 3: light years. It may be that that's just a small
4:22
Speaker 3: part of the universe and there are other bits where,
4:25
Speaker 3: you know, the acceleration is not sorry, the expansion is
4:30
Speaker 3: not accelerating, and the two sort of even out. That's
4:37
Speaker 3: a caveat that we can't really deal with because with
4:40
Speaker 3: no idea what happens beyond the little bubble of the
4:43
Speaker 3: universe that we can observe, And certainly it's true within
4:46
Speaker 3: that bubble the acceleration is basically or the accelerated sorry,
4:52
Speaker 3: the accelerated expansion is basically the same in all directions.
4:57
Speaker 3: So it's a property of space itself. It's a fundamental property.
5:01
Speaker 3: Whereas dark matter, yes, that's got gravitation and pull stuff in,
5:07
Speaker 3: it's definitely clumpy. It actually, well, it follows the visible matter.
5:15
Speaker 3: That was the way it was thought to be when
5:17
Speaker 3: we first started thinking about dark matter, but now I
5:19
Speaker 3: think it's probably the other way around. That the visible
5:21
Speaker 3: matter is visible because dark matter acted as a kind
5:25
Speaker 3: of scaffolding in the early universe for the gravitational pull
5:30
Speaker 3: of dark matter in order to bring the clouds of
5:33
Speaker 3: hydrogen together, compress them and make them turn into stars.
5:36
Speaker 3: So that's why dark matter and normal matter stick together.
5:42
Speaker 3: But they do stick together. And when you know, when
5:45
Speaker 3: you observe the universe on the larger scales, we can
5:48
Speaker 3: see by for example, gravitational lensing, we can see that
5:53
Speaker 3: the dark matter definitely follows the visible matter. So there
6:01
Speaker 3: will be places where there's hardly any visible matter and
6:05
Speaker 3: there's hardly any dark matter, whereas with the dark energy
6:09
Speaker 3: it's everywhere, and so there are fundamental differences between them,
6:13
Speaker 3: and I suspect in the end, you know, if we
6:16
Speaker 3: were having this conversation in twenty to thirty years time,
6:21
Speaker 3: we probably will be actually, But anyway, when we look
6:25
Speaker 3: back on this, we might have realized that the dark
6:30
Speaker 3: energy is a boson, it's a force particle, whereas dark
6:34
Speaker 3: matter is some sort of matter particle made of quarks
6:38
Speaker 3: and things of that sort. So probably fundamental differences rather
6:42
Speaker 3: than just that sort of the idea that they might
6:46
Speaker 3: be the same thing but with a different polarity. I
6:49
Speaker 3: don't think the evidence supports that.
6:52
Speaker 1: I suppose we could say Daryl's fallen for the naming
6:55
Speaker 1: era of these two things, because you've said all along
7:01
Speaker 1: that dark energy is poorly named. It's not really the
7:06
Speaker 1: right thing to call it.
7:08
Speaker 3: Well, neither of them are really, you know, the invisible
7:13
Speaker 3: would have been far better, but dark. It's actually Fritz
7:17
Speaker 3: Vicki back in nineteen thirty three who labeled this stuff
7:21
Speaker 3: dark matter. He didn't what it was, and he said
7:23
Speaker 3: there must be something there, which he was calling dark matter,
7:26
Speaker 3: that's providing enough of a gravitational attraction to stop clusters
7:31
Speaker 3: of galaxies from dispersing altogether.
7:35
Speaker 1: Interesting. They'll figure it out one day, but for now
7:40
Speaker 1: it remains a mystery. But there's got to be something
7:43
Speaker 1: in that connection between real matter and dark matter plumping.
7:49
Speaker 1: Like if you go somewhere there isn't much matter, there
7:52
Speaker 1: isn't much dark matter. So there's got to be some
7:56
Speaker 1: connection there that will give us the answer day if
8:00
Speaker 1: we can figure out what the connection is.
8:03
Speaker 3: Yeah, well, the connections gravity and it's the.
8:06
Speaker 1: Only well, we haven't figured that out either.
8:09
Speaker 3: No, that's right. We basically we know how it behaves.
8:12
Speaker 3: We know very accurately how it behaves. We don't know
8:14
Speaker 3: what it is.
8:17
Speaker 1: It is indeed a mystery, Darryl. But coming up with
8:20
Speaker 1: an idea always is a good way to get people thinking.
8:24
Speaker 1: And maybe maybe somewhere in the dark reaches of the Internet,
8:29
Speaker 1: someone will hear this and go, hang on, Daryl's onto something,
8:32
Speaker 1: and then he'll go to his Wikipedia or his Encyclopedia Britannica,
8:37
Speaker 1: or his Funk and Wagnoff, flick a few pages and go,
8:41
Speaker 1: I've got it figured out thanks to Daryl's question on
8:44
Speaker 1: space nuts. So you know there are no dumb questions
8:47
Speaker 1: in astronomy, are there for it?
8:49
Speaker 3: No, that's absolutely right. There's just dumb answers from the
8:53
Speaker 3: LOCs and mood.
8:55
Speaker 1: It's Daryl, great to hear from you. Our next question
8:58
Speaker 1: comes from the fields of Norway, and this question goes
9:05
Speaker 1: by the name of Some will recognize this slaty bar
9:08
Speaker 1: fast listening from the fjords of Norway. Last week, someone
9:12
Speaker 1: asked the question about viewing the birth of the Sun,
9:15
Speaker 1: and Fred answered with the hypothetical mirror in space. My
9:20
Speaker 1: question is if we calculated the exact location in space
9:24
Speaker 1: for the Sun four point six billion years ago and
9:27
Speaker 1: pointed a telescope at those coordinate coordinates, would we see anything? Hmmm?
9:37
Speaker 3: Slutty Bartfast won an award, didn't he, for the fields
9:39
Speaker 3: of Norway? So that's right, that's right. Yes, that was
9:44
Speaker 3: because he designed the designed them. Yes, yes, he made fjords.
9:50
Speaker 1: That's right, that was what slati Vartfast was famous for.
9:54
Speaker 3: One of my favorite Douglas Adam's characters.
9:56
Speaker 1: Ah. Yeah, I think the moment where he's forced say
10:00
Speaker 1: his name is one of the the funniest moments I've
10:04
Speaker 1: ever experienced, because first time I ever listened to it,
10:08
Speaker 1: I listened to the audio version that just caught me
10:13
Speaker 1: so beautifully. I just couldn't stop cackling.
10:17
Speaker 3: Right, No, it's a pick stuff. One of the all
10:21
Speaker 3: time greats in science fiction.
10:23
Speaker 1: Absolutely is.
10:24
Speaker 3: Yeah. Anyway, the answer to Slatly Bartfast's question is no,
10:30
Speaker 3: So do you want to keep going?
10:33
Speaker 1: Well, I mean he's basically saying, so, you're saying, we
10:36
Speaker 1: would not see anything if we could figure out where
10:39
Speaker 1: the son was four point six billion years ago and
10:41
Speaker 1: then pointed a telescope at it.
10:43
Speaker 3: Yeah, because first of all, the son isn't there anymore?
10:47
Speaker 1: No, I know where it is.
10:49
Speaker 3: Yes, the odds are that point. You let me see
10:56
Speaker 3: which way you're pointing.
10:57
Speaker 1: I'm pointing that way that way.
10:59
Speaker 3: That's good, that's probably correct to In fact, it's behind
11:02
Speaker 3: me too, it's.
11:03
Speaker 1: To my it's to my right rear.
11:07
Speaker 3: All right. Okay, that's a bit intimate, isn't it anyway?
11:11
Speaker 1: Never mind? Yeah, the sun is certainly not shining out
11:16
Speaker 1: of that particular part of me at the moment, but
11:19
Speaker 1: it's it's in that kind of direction.
11:23
Speaker 3: It's all your funds think, though, is they?
11:26
Speaker 1: Glad? I don't even have any I don't get fan mail.
11:30
Speaker 1: Good abuse.
11:32
Speaker 3: Well, anyway, notwithstanding all that, what was the question again? Yes,
11:37
Speaker 3: if you could work out where the sun was four
11:39
Speaker 3: point six billion years ago and point a telescope at it,
11:44
Speaker 3: you wouldn't see anything because the point where the sun
11:48
Speaker 3: was formed and it will be only a few at
11:54
Speaker 3: most one hundred million light years away. So yeah, you've
11:59
Speaker 3: got to look back time. But you've got to look
12:01
Speaker 3: back time. It's probably less than one hundred million years
12:05
Speaker 3: and the sun one hundred million years ago was a
12:07
Speaker 3: lot like what it is now. It's slightly hotter, and
12:10
Speaker 3: a few other things that were going on at the time,
12:13
Speaker 3: but not much different. But the fact is, it's.
12:15
Speaker 1: Not there, it's here.
12:18
Speaker 3: So even I think I said in that thought experiment,
12:23
Speaker 3: you'd have to have a mirror something like two point
12:28
Speaker 3: three billion light years away, which is going to take
12:32
Speaker 3: you quite a lot of time to put in place anyway.
12:36
Speaker 3: But if that mirror was looking back to wherever the
12:39
Speaker 3: Sun was formed, and we don't know where that was,
12:43
Speaker 3: we know it's within the present vicinity of the Sun
12:45
Speaker 3: because stars don't move that fast. Anyway, you have this
12:50
Speaker 3: mirror and you capture a reflection of the Sun being born.
12:55
Speaker 3: That thought experiment I think would work. But just king
13:00
Speaker 3: where the son was when it was born isn't going
13:04
Speaker 3: to tell you very much.
13:06
Speaker 1: There's got to do something there though, right, Well, yeah.
13:09
Speaker 3: Probably other stars and things like that, you know. It's
13:12
Speaker 3: just part of the solar neighborhood.
13:14
Speaker 1: Yeah. Yeah, our son, I suspect came from, you know,
13:19
Speaker 1: a pretty rough neighborhood, and that's why it left it
13:23
Speaker 1: inherited money and managed to manage to get away.
13:27
Speaker 3: Yeah, but then it discovered drugs, didn't it.
13:30
Speaker 1: Yeah, Well that's that's what happened is yes, and and
13:33
Speaker 1: then we turned up and yeah, well hell broke loose. Yes,
13:38
Speaker 1: but there'd be nothing to say. There nothing to say
13:41
Speaker 1: there now.
13:43
Speaker 3: Nothing that's really of any interest, just to other stars.
13:45
Speaker 1: Yeah, yeah, although we're still looking for Earth's siblings, sorry,
13:50
Speaker 1: the son's siblings. That's that's right, because there are there
13:53
Speaker 1: would be some, but they wouldn't be there either, would they.
13:56
Speaker 3: Well that you know that the stars and that I'm sorry.
14:00
Speaker 3: The stars that were born alongside the Sun in the
14:03
Speaker 3: same cloud of gas and dust are probably not that
14:06
Speaker 3: far away, but they Yeah, one hundred yeah, one hundred
14:16
Speaker 3: million light years I mentioned before. It's probably much much
14:19
Speaker 3: less than that. I don't know quite why I thought
14:22
Speaker 3: of that anyway, because the center of our galaxy is
14:26
Speaker 3: only twenty five thousand light years away, So I probably
14:30
Speaker 3: meant a hundred thousand light years when I said a
14:34
Speaker 3: hundred million. Something's going wrong with this program today, I'm
14:38
Speaker 3: not quite sure.
14:39
Speaker 1: Well, it's it's six hundred that's what it is.
14:43
Speaker 3: That's what it is. There's a there's a gap in
14:46
Speaker 3: space time has opened up, which I'm floundering in at
14:49
Speaker 3: the moment. Yeah, so you know, you might it's it's
14:53
Speaker 3: not gone very far. That's what I'm saying. The siblings
14:56
Speaker 3: from the Sun born in the same gas cloud from
15:00
Speaker 3: the Sun. Probably within they might even be within the
15:03
Speaker 3: nearest one hundred million, sorry, one hundred light years, not
15:07
Speaker 3: million light years. So, and that's why we can use
15:14
Speaker 3: very high resolution instruments, ones that really analyze the spectrum
15:20
Speaker 3: of a star in great detail, but need the star
15:23
Speaker 3: to be relatively bright. That's why we can use that
15:25
Speaker 3: technology with the real hope of finding the solar siblings,
15:29
Speaker 3: because it's by analyzing the spectrum the chemical composition of
15:33
Speaker 3: a star in very great detail. That's how we would
15:37
Speaker 3: identify that the star had exactly the same chemical composition
15:41
Speaker 3: as the Sun and could be regarded as likely to
15:44
Speaker 3: be a solar sibling.
15:46
Speaker 1: Okay, we may one day find one of them, but
15:50
Speaker 1: who knows. Yeah, we'll see. And thank you slightly Bardfast,
15:56
Speaker 1: whatever your real name is. That maybe that's it could be. Thanks,
16:00
Speaker 1: thanks for the question, and thank you for sending me
16:02
Speaker 1: the Babelfish so I could read the question. That was
16:06
Speaker 1: a good idea, very very good idea. This is space nuts.
16:10
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18:03
Speaker 1: It's you know, that moment where they realized they had
18:08
Speaker 1: a problem on Apollo thirteen sounded much better in the movie.
18:14
Speaker 1: It just yeah, you.
18:18
Speaker 3: Brew, you broke up, Ah, exactly as you were saying.
18:21
Speaker 1: I noticed that, and I was going to keep talking
18:23
Speaker 1: until you came back.
18:24
Speaker 3: But tell me what you said.
18:26
Speaker 1: I said that that moment where Apollo thirteen realized they
18:30
Speaker 1: had that problem sounded much better in the movie. Yeah,
18:35
Speaker 1: it was. It nearly as dramatic in real life, was it. Well, well,
18:39
Speaker 1: it was dramatic, but the way they announced it, yea.
18:43
Speaker 1: They basically just said, yeah, this button didn't work more
18:47
Speaker 1: or less.
18:49
Speaker 3: Yeah, I picked stuff. I mean, it's always me Tingles
18:52
Speaker 3: Apollo thirteen.
18:54
Speaker 1: Absolutely. Yeah. Now, Freid, let's move on to our third question.
18:59
Speaker 1: This one it comes from.
19:01
Speaker 4: Beyond Evening Fred and Andrew. I have to thank you
19:07
Speaker 4: for a fantastic podcast. My first choice every evening among
19:14
Speaker 4: lots of interesting stuff, it's the first one I choose.
19:20
Speaker 4: It's regarding the question you had about temperature or black holes.
19:25
Speaker 4: I must ask you to clarify. If material acrets close
19:33
Speaker 4: to your horizon, it's millions of degrees hot. If I
19:39
Speaker 4: follow the material spiraling inwards, it does not suddenly become
19:44
Speaker 4: cold when it's interesting horizon. Right, it's still extremely hot,
19:50
Speaker 4: maybe even hotter, even if it's supposedly hard to measure,
19:54
Speaker 4: because it's hard to get a thermometer in there and
19:58
Speaker 4: have a reference.
20:00
Speaker 5: But it extremely hot, but seems called to an outside
20:05
Speaker 5: observer because it does not radiate anything. But maybe it
20:10
Speaker 5: could be clarified somehow. It's not magic that it suddenly
20:15
Speaker 5: gets called. It just stops emitting, right, Take care. It's
20:22
Speaker 5: beyond from Gothenburg. I love your show.
20:26
Speaker 1: Thank you. Beyond that Babelfish is working well because his
20:29
Speaker 1: English was excellent.
20:31
Speaker 3: He lives in a nice place as well. Gottenberg's got
20:33
Speaker 3: a very nice city center with a lovely opera house. Yeah.
20:37
Speaker 1: I haven't been there, In fact, I haven't been to
20:39
Speaker 1: Sweden yet, but it's on the wish list, so we'll
20:44
Speaker 1: see how we go. Now. He's referring to a question
20:47
Speaker 1: that came from Casey in Colorado when she was asking
20:50
Speaker 1: about the temperature of a black hole. So he's basically
20:55
Speaker 1: kind of saying, look, I understand what you were saying
20:59
Speaker 1: when you answered Casey, but now everyone thinks they're cold
21:03
Speaker 1: when they're probably not cold. They're just not emitting anything.
21:07
Speaker 1: Is that right?
21:08
Speaker 3: Yeah, that's that's right. They're cold because they're not emitting anything.
21:14
Speaker 3: But beyond's right that you know the temperature of the
21:20
Speaker 3: accretion disc, and probably the way to look at it
21:23
Speaker 3: is the temperature of the event horizon. There's millions of
21:26
Speaker 3: degrees because that's where all this stuff is circulating at
21:31
Speaker 3: high speed and with huge amounts of energy and emitting
21:35
Speaker 3: X rays. It disappears over the event horizon at very
21:41
Speaker 3: high temperature, and presumably within the event horizon it's still
21:45
Speaker 3: got that high temperature. But then it hits the black hole.
21:49
Speaker 3: It's sucked in, and if you could measure the temperature
21:54
Speaker 3: of the black hole itself, you'd find it was virtually
21:58
Speaker 3: absolute zero, very very temperature. Okay, because it's not emitting anything.
22:04
Speaker 3: Stuff's going in and it is it is hard to imagine,
22:09
Speaker 3: and Bjorn mentioned magic, and that's almost what it is.
22:14
Speaker 3: You know, stuff that's going in at very high temperature.
22:16
Speaker 3: But if you could measure the black hole itself, supposing
22:19
Speaker 3: it stopped recreating material, then you could then measure its temperature.
22:23
Speaker 3: It will be virtually zero.
22:25
Speaker 1: Well well, well, they are so complicated though, aren't they.
22:29
Speaker 1: I mean, we we're still learning a lot about black holes,
22:35
Speaker 1: and then we're starting to image a few of them.
22:38
Speaker 1: We've got a couple of good pickies now. But they
22:44
Speaker 1: are still mesmerizing and mystifying, because until dark matter came along,
22:49
Speaker 1: we got more questions about black holes than anything else.
22:52
Speaker 1: They are the thing that people want us to unravel
22:55
Speaker 1: in terms of understanding. But we're I think we're a
22:58
Speaker 1: long way away from that at the moment, aren't we. Actually?
23:03
Speaker 3: I think you know that we know a lot about
23:06
Speaker 3: black holes, considering that sixty years ago nobody believed they existed. Yeah,
23:16
Speaker 3: and we've observed them. We've actually observed the radiation coming
23:21
Speaker 3: from the the the accretion disk, the region around the
23:25
Speaker 3: event horizon. We've we've observed the effectively the shadow of
23:28
Speaker 3: the event horizon of several black holes now and even
23:33
Speaker 3: detected the polarization of the material that's been sucked into it.
23:36
Speaker 3: And this is extraordinary stuff. These are measurements that really
23:40
Speaker 3: only a few years ago would have been thought to
23:41
Speaker 3: be impossible, but we're I think, doing it rather well.
23:45
Speaker 3: So we're still learning about black holes. They are and
23:49
Speaker 3: that's the reason why they're so fascinating is that they
23:52
Speaker 3: are completely counterintuitive. How do you have something that's simultaneously
23:56
Speaker 3: at zero and a million degrees and that's what you've got.
24:01
Speaker 3: So yeah, so it's yeah, there's there's still they're still
24:06
Speaker 3: very very interesting object.
24:08
Speaker 1: But back to Beyond's question, the temperature is zero absolute zero?
24:17
Speaker 1: Were thereabout because of the fact that it.
24:20
Speaker 3: Doesn't It doesn't really get anything exactly certainly, so the
24:24
Speaker 3: way to imagine it, I think, and this probably puts
24:27
Speaker 3: it more succinctly. Yes, well, well it's a creting. You
24:31
Speaker 3: can't you can't see the black hole because it's surrounded
24:33
Speaker 3: by this hot material that very high temperature is being
24:37
Speaker 3: swallowed into it. But if there was, if that supply
24:40
Speaker 3: of gas ran out and the black hole stopped recreating,
24:43
Speaker 3: then you would and you could measure its temperature, then
24:46
Speaker 3: it will be zero, effectively be absolute zero, a little
24:49
Speaker 3: bit above but not very much.
24:51
Speaker 1: Okay, there you go, Beyond, and I'm looking at photographs
24:55
Speaker 1: of Gottenburg. It's it is an absolute beauty of a city,
25:00
Speaker 1: isn't it? What a lovely part of the world. Yeah,
25:04
Speaker 1: very lucky, nice trams. Thanks bien. Great to hear from
25:10
Speaker 1: you in Sweden.
25:14
Speaker 5: Okay, we take your being with air space nuts.
25:18
Speaker 1: And believe it or not. Our next question comes from Sweden.
25:23
Speaker 1: Does the expansion of space mean that the universe gains
25:27
Speaker 1: more meters or are the meters becoming longer? Related to this,
25:32
Speaker 1: is it space only that is expanding or is it
25:36
Speaker 1: space time? If so, what's happening to the time part
25:41
Speaker 1: of it? Is time expanding to what would that mean?
25:45
Speaker 1: Thanks for a most interesting podcast. Peter from I'm going
25:50
Speaker 1: to pronounce this incorrectly falloon in Sweden. So yeah, hopefully
25:56
Speaker 1: I got that right. I think my Babelfish can't translate
26:00
Speaker 1: and the sweet Swedish.
26:02
Speaker 3: Well, if you put it the other way around, put
26:04
Speaker 3: in the other ear, yes.
26:08
Speaker 1: That'll do it.
26:10
Speaker 3: So, yes, that's a great question. And so my view,
26:15
Speaker 3: you know, the intuitive view, which is based on a
26:21
Speaker 3: few years of thinking about this kind of thing. The
26:26
Speaker 3: meat the meters are becoming longer, and that's sort of
26:31
Speaker 3: illustrated by the fact that the wavelength of radiation is
26:34
Speaker 3: getting longer. You know that radiation had a particular wavelength
26:38
Speaker 3: when it was emitted, and as the universe has expanded,
26:43
Speaker 3: whatever it's coming from, whether it's a distant galaxy or
26:46
Speaker 3: a quasar or whatever, as the universe has expanded, that
26:49
Speaker 3: radiation has been stretched, which means that the meat has
26:52
Speaker 3: been stretched, because the frequency remains the same except when
27:00
Speaker 3: you observe it from our vantage point in the depths
27:05
Speaker 3: of the universe. Yeah, forget about the frequency, that's a
27:11
Speaker 3: furfe but the wavelength, the wavelength stretches so the time
27:15
Speaker 3: that the length scale is increasing. In fact, there's there's
27:20
Speaker 3: a thing called the scale factor of the universe, and
27:24
Speaker 3: it's very easy to prove. It's one of the most
27:27
Speaker 3: simple geometrical equations in cosmology. The scale factor of the
27:31
Speaker 3: universe now compared with when the light was emitted. The
27:36
Speaker 3: ratio of the two is equal to one over one
27:38
Speaker 3: plus said, where z is the red shift of the
27:40
Speaker 3: light that you're measuring. And so there's this direct link
27:43
Speaker 3: between the sort of scale size of the universe, which
27:46
Speaker 3: is the length of meter effectively, and the red shift
27:50
Speaker 3: that we measure when we look deep into the universe.
27:55
Speaker 3: You look as you've got a question.
27:57
Speaker 1: Now I'm confused. So what you basically say in regard
28:00
Speaker 1: to his question that the met is expanding? So a
28:06
Speaker 1: meter is not a meter?
28:08
Speaker 3: Well, it's it's still a meter, but it's a different meter, okay,
28:17
Speaker 3: because the scale factor of the universe was less when
28:21
Speaker 3: the light was emitted. This is the thing, you know.
28:23
Speaker 3: You've got two different reference frames here. That's why this
28:27
Speaker 3: stuff gets a little bit complicated because in our reference frame,
28:31
Speaker 3: the meter is longer. But if you were traveling along
28:35
Speaker 3: with your meter stick as it as it sped through
28:39
Speaker 3: the universe, it will be changing in length. It would
28:42
Speaker 3: it would sorry appear to be the same length.
28:46
Speaker 1: Right, I'm sorry. This is just it's mind bending, mm hmm,
28:55
Speaker 1: isn't it it?
28:57
Speaker 3: It bends mine as well, and something similar happens to time.
29:02
Speaker 3: But once again, so we are we're still inside the universe,
29:07
Speaker 3: but where we're observers from in a different reference frame
29:13
Speaker 3: from when the light was emitted. Because that's what we're
29:16
Speaker 3: talking about. We're talking about being able to measure the
29:18
Speaker 3: expansion of the universe through the through the light waves.
29:23
Speaker 3: So so and we know that time dilation took place,
29:28
Speaker 3: we can we can measure that by looking at this
29:31
Speaker 3: rise and fall rates of supernova in the distant universe,
29:34
Speaker 3: and they actually appear to rise and fall slower, So
29:37
Speaker 3: it is the time element of that changes as well.
29:41
Speaker 1: Okay, I think he chose a meter because the meter
29:46
Speaker 1: was defined by the International System of Units as the
29:51
Speaker 1: length of the path light travels in a vacuum during
29:54
Speaker 1: a time in the interval of one two hundred and
29:57
Speaker 1: ninety nine million, seven hundred and ninety two four hundred
30:01
Speaker 1: and fifty eighths of the second.
30:05
Speaker 3: Yeah, that's how it's that's how it's defined today. Originally
30:09
Speaker 3: defined as being what was it, one four hundred thousand
30:12
Speaker 3: of the circumference of the Earth.
30:13
Speaker 1: I can't remember, Yeah, I.
30:14
Speaker 3: Can't something like that, all right, okay, so well it
30:19
Speaker 3: would be one forty yeah one. Anyway, so it was
30:23
Speaker 3: it was. It was related to the circumference of the Earth.
30:26
Speaker 3: I don't do the sums anymore. My brain's fried today.
30:29
Speaker 3: I don't know why. I mean, you're right, I think
30:30
Speaker 3: it's episode three six hundred. Yeah, is a relativistic phenomenon
30:34
Speaker 3: taking place here.
30:36
Speaker 1: It's just messing us up. I mean, we need a
30:38
Speaker 1: holiday of some kind. But anyway, hopefully that helped Peter,
30:43
Speaker 1: I don't know, but I think somewhere in there we
30:48
Speaker 1: did answer a question. Thanks for sending it in, and
30:51
Speaker 1: and good to have a very Scandinavian sort of six
30:56
Speaker 1: hundred episode. So yeah, I mean we've got slightly fast,
31:00
Speaker 1: We've got Sweden a couple of times over Norway and
31:04
Speaker 1: then South Australia. Okay, well anyway close enough plus enough.
31:09
Speaker 3: South Australia is not known for its fjords, but it
31:11
Speaker 3: is a nice place.
31:12
Speaker 1: It is a lovely place, except it was pouring rain
31:15
Speaker 1: and gale force wins when we visited. But anyway, that's
31:17
Speaker 1: the way it goes. Thank you Peter, Bjorn, slightly badcast
31:21
Speaker 1: and Darryl for sending in questions. If you've got questions
31:23
Speaker 1: for us, please send them in to us via our website,
31:26
Speaker 1: spacenuts podcast dot com, space nuts dot Io. Click on
31:31
Speaker 1: the AMA button which stands for Ask Me Anything and
31:34
Speaker 1: send us your text or audio questions. Don't forget to
31:37
Speaker 1: tell us who you are and we're from. We'd love
31:39
Speaker 1: to hear from you, especially if you haven't sending questions before. Also,
31:44
Speaker 1: if you'd like to help us out, please wherever you
31:47
Speaker 1: listen to us, leave reviews because the more reviews the better,
31:53
Speaker 1: the more we move up the relativistic food chain that
31:58
Speaker 1: is podcast world, and we get more listeners. Perhaps that's
32:03
Speaker 1: that's the aim of the game. Anyway, if you do
32:06
Speaker 1: that for us, that'd be great. And Fred, thank you
32:09
Speaker 1: very much. Nice to chat. We'll catch you on the
32:10
Speaker 1: next episode.
32:12
Speaker 3: Sounds great, Andrew, I hope we get our breath boat
32:15
Speaker 3: before then.
32:16
Speaker 1: Yes, yes, it's been a bit tiring, hasn't Itred. We
32:19
Speaker 1: got there in the Professor Fred Wartson, Astronomer at Large,
32:22
Speaker 1: and he'll be back with us next week here in
32:24
Speaker 1: the studio. We thank him too for all the work
32:26
Speaker 1: he's done over these last well actually he doesn't turn
32:30
Speaker 1: up for most so the last four episodes that he's
32:33
Speaker 1: been with us. In fact, he couldn't be with us
32:35
Speaker 1: today because we told him he could have every six
32:38
Speaker 1: hundredth episode off and from me Andrew Dunkley, thanks for
32:42
Speaker 1: your company. We'll see you on the next episode of
32:44
Speaker 1: Space Nuts. Bye bye.
32:47
Speaker 5: You'll listening to the Space Nuts podcast.
32:51
Speaker 4: Available at Apple Podcasts, Spotify, iHeartRadio, or your favorite podcast player.
32:57
Speaker 1: You can also stream on demand buy dot com. This
33:01
Speaker 1: has been another quality podcast production from Nights dot com