Latest / Space Nuts: Astronomy Insights & Cosmic Discoveries / Black Holes, Light Speed & Oceanic Exoplanets: #498 - Diving Deep into Your Space Queries

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Black Holes, Light Speed & Oceanic Exoplanets: #498 - Diving Deep into Your Space Queries · Space Nuts: Astronomy Insights & Cosmic Discoveries

0:00
Speaker 1: Hello again, thanks for joining us. This is a Cuan
0:02
Speaker 1: edition of Space Nuts. This is where the audience asks
0:06
Speaker 1: us questions and we refer to somebody else. And in
0:10
Speaker 1: today's episode, we are going to talk about whether or
0:14
Speaker 1: not we can see our own reflection in space. That's
0:16
Speaker 1: a question from Tony. Are we living in a holographic universe?
0:21
Speaker 1: Charles wants to know, David is asking about black holes
0:24
Speaker 1: versus light who wins that war? And duncan liquid planets?
0:29
Speaker 1: Are there any out there? We'll find out on this
0:32
Speaker 1: episode of Space Nuts fifteen, Channel ten nine Ignition Squench
0:41
Speaker 1: Space Nuts NI or three two Space Nuts as and
0:48
Speaker 1: I reported Neil's goods. And joining us to sort all
0:52
Speaker 1: of that out is Professor John ty Horner from the
0:54
Speaker 1: University of Southern Queensland. Hi, Johnny, how you doing. I'm good.
0:59
Speaker 1: It's feels like second since we last spoke.
1:02
Speaker 2: Absolutely time flies when you're having fun. I think this.
1:06
Speaker 1: Let's muck in, as they say in your part of
1:09
Speaker 1: the world. Let's go to our first question. This one
1:13
Speaker 1: comes from Honey. Hi, guys, Given the cosmoss has black holes,
1:19
Speaker 1: gravity waves, gravitational lensing, light echoes, and dust cloud reflections,
1:26
Speaker 1: any chance we could ever see a reflection of our
1:29
Speaker 1: Milky Way galaxy. Love the show, Tony from Marrickville, which
1:33
Speaker 1: is a suburb of Sydney. Thanks Tony. What are your thoughts, Johnny.
1:38
Speaker 2: I think that's a short I'm sure a long answer
1:40
Speaker 2: to this. I think the short answer is I can
1:42
Speaker 2: think of nowhere that we could get a resolved image,
1:46
Speaker 2: you know, so we're not going to get something like
1:48
Speaker 2: a mirror held up to reality where we get a
1:50
Speaker 2: beautiful picture of the Milky Way galaxy reflected back to us.
1:54
Speaker 2: The different phenomena that can bend light and change its
1:56
Speaker 2: direction are often ly to the amount of mass, So
2:00
Speaker 2: you've got a black hole or a star or something
2:05
Speaker 2: like that. And under Einstein's series of general relativity, the
2:09
Speaker 2: idea is that mass curve space, so like tries to
2:13
Speaker 2: go in what it thinks is a straight, direct, straight line,
2:16
Speaker 2: but because the space is curved, it gets deflected by
2:19
Speaker 2: following the shortest path through the curve space. So that's
2:22
Speaker 2: how you get gravitational lensing. How you get light being bent.
2:26
Speaker 2: Now like traveling really really quickly, so nearly all the
2:29
Speaker 2: time that deflection is relatively small. You're not talking about
2:32
Speaker 2: light changing through ninety degrees. You talk about it changing
2:35
Speaker 2: through a few degrees at most, and that kind of
2:40
Speaker 2: you could link to the idea of the escape velosity.
2:42
Speaker 2: In order to get it changing through a really substantial direction,
2:45
Speaker 2: you'd have to be very close into a black hole
2:47
Speaker 2: or something like that. And at that point you're almost
2:50
Speaker 2: falling into the black hole and everything is doomed. So
2:53
Speaker 2: you need to set up a really unusual set of
2:56
Speaker 2: circumstances for some light from the Milky Way to be
2:59
Speaker 2: bent by let's say three four degrees by one source,
3:02
Speaker 2: and then go to one other source and be bent
3:04
Speaker 2: again and again and again. That chain of events would
3:07
Speaker 2: probably get only a tiny time a little bit. So
3:09
Speaker 2: I think you could imagine a scenario where there are
3:13
Speaker 2: packets of light photons from the Milky Way that get
3:17
Speaker 2: back to the Milky Way and that mechanism, but there'd
3:19
Speaker 2: be barely any and we wouldn't really be able to
3:21
Speaker 2: detect them if there were any at all. If there
3:24
Speaker 2: were dust clouds near the Milky Way, some of the
3:27
Speaker 2: light from the Milky Way would reflect off them. And
3:29
Speaker 2: this is like the beautiful reflection nebulae we see Paul
3:32
Speaker 2: Dotta through our galaxy the things that we get fabulous
3:36
Speaker 2: asher photos off. Now, I was imaging doing some master
3:40
Speaker 2: of photography a few months ago, the larger and the
3:42
Speaker 2: small Magellanic clouds, and learning a new photograph processing tool
3:47
Speaker 2: that friends of mine who were incredibly gifted ATTERA photographers
3:51
Speaker 2: taught me how to use, and playing with that and
3:53
Speaker 2: stretching and bending and fiddling. There's a persistent feature around
3:58
Speaker 2: the Magellanic cloud that looks like dust that appears to
4:01
Speaker 2: be structured that I thought was I've overdone it on
4:04
Speaker 2: the image, And then I looked at a different image
4:06
Speaker 2: and the same structures were there at the same time.
4:08
Speaker 2: So there's clearly dust and gas that has been stripped
4:11
Speaker 2: off the large magilanic cloud by the Milky Way that
4:16
Speaker 2: is illuminated enough that it is brighter than the background
4:19
Speaker 2: pitch black of the sky for my camera to pick
4:21
Speaker 2: it up. That means that there is light hitting that
4:25
Speaker 2: and bouncing back to us to see it, and some
4:28
Speaker 2: fraction of that light will be light from the Milky Way.
4:31
Speaker 2: Now I don't know enough about that there, but I've
4:33
Speaker 2: not been able to find much discussion online. Selves fascinated
4:36
Speaker 2: when I saw it on these photos repeatedly, but I
4:40
Speaker 2: would hazard that some of the light that is illuminating
4:43
Speaker 2: this gas and dust that is around the large Magilanic
4:45
Speaker 2: cloud is light from the Milky Way reflected back to us,
4:49
Speaker 2: but that isn't anywhere near enough to get an image.
4:52
Speaker 2: It's a bit like when you're looking on a really
4:55
Speaker 2: foggy day and the sky is really bright. You can't
4:57
Speaker 2: see an image of the sun from that light. You've
4:59
Speaker 2: just got a scattered at you in all directions. Help
5:02
Speaker 2: we lost all of the information. So I think we
5:05
Speaker 2: do get reflected light from the Milky wacoing back and
5:08
Speaker 2: things like that, but to actually get an image, a
5:11
Speaker 2: reflected image like you'd see the mirror, that to me
5:14
Speaker 2: is beyond the bounds of possibility. The nearest will get
5:18
Speaker 2: is finding galaxies that look very similar to our arm
5:21
Speaker 2: so they give us a perspective of what we would
5:23
Speaker 2: look like from the outside.
5:25
Speaker 1: Yeah, this is one of Fred's great wishes. If we
5:28
Speaker 1: were asked a question not so long ago, if you
5:31
Speaker 1: could do anything, if you could just take a spacecraft
5:34
Speaker 1: anywhere in the universe and look at something that you
5:36
Speaker 1: want to see, what would it be. And Fred's wish
5:39
Speaker 1: was to go outside of our galaxy so we could
5:41
Speaker 1: look at it and see exactly what shape it was.
5:44
Speaker 1: We have a pretty good idea, but we've never been
5:48
Speaker 1: able to image it. We don't know for sure if
5:51
Speaker 1: it's got the number of spiral arms that they assume
5:53
Speaker 1: it's got, or anything like that. So that was Fred's
5:58
Speaker 1: you know, if you could do anything at the snap
6:00
Speaker 1: of his fingers, looking at our galaxy from outside was
6:05
Speaker 1: one of his wishes, So Tony, unfortunately, no, we cannot
6:09
Speaker 1: see a reflection of our galaxy in any way or form.
6:13
Speaker 1: We probably are seeing light bounce back to us, as
6:17
Speaker 1: Johnny was explaining, from our own galaxy, but it certainly
6:22
Speaker 1: wouldn't give us an image. But thanks for the question.
6:25
Speaker 1: Great to hear from you. Our next question comes from Charles.
6:28
Speaker 1: This is a short, sweet, but rather difficult one to answer.
6:33
Speaker 1: What do you think of the theory that we live
6:35
Speaker 1: in a holographic universe? Now, this is something I've seen
6:39
Speaker 1: popping up time and time again in the popular press,
6:43
Speaker 1: and I suppose we should explain what a holographic universe
6:46
Speaker 1: is before we decide whether or not we live in one.
6:49
Speaker 2: Yeah, this is one of the ones that breaks my head.
6:52
Speaker 2: So your answer to this will be neither good or
6:57
Speaker 2: akura issispact, because this is far from our own expertise.
7:00
Speaker 2: Do my best. The holographic universe stuff is tied to
7:04
Speaker 2: string theory, is my understanding, and to me is at
7:08
Speaker 2: the point where you're bordering along the boundary between science
7:11
Speaker 2: and philosophy because you're starting to ask questions that we
7:14
Speaker 2: have no way of testing yet, and that's really hard. Now,
7:18
Speaker 2: this all ties down to very mathematical and very theoretical
7:22
Speaker 2: studies of the universe. I think getting back to about
7:25
Speaker 2: the nineteen nineties where people found that in some versions
7:29
Speaker 2: of the mass of string theory, you can get three
7:33
Speaker 2: dimensional stuff being represented in a two dimensional way without
7:37
Speaker 2: losing any data. And it's an answer to some of
7:41
Speaker 2: the issues to do with information and black holes. It's
7:43
Speaker 2: one of the things that led people to suggest that
7:46
Speaker 2: you can get information that does into black holes, is
7:49
Speaker 2: not lost, but might be stored in the event horizon
7:51
Speaker 2: and all these kind of things. Now, my understanding of
7:54
Speaker 2: it that you can tell by that explanation is kind
7:56
Speaker 2: of limited. It's not my area of expertise. It is
8:00
Speaker 2: called the holographic principle, and that leads to the idea
8:03
Speaker 2: of the holographic universe. So the idea that you can
8:07
Speaker 2: get essentially a two dimensional representation of all the data
8:13
Speaker 2: you need to have a three dimensional thing means that
8:17
Speaker 2: you could have, in some way a three dimensional appearing
8:22
Speaker 2: thing actually only be two dimensional a holograph essentially, So
8:25
Speaker 2: that's what the holograph is all about. And I don't
8:28
Speaker 2: fully understand that. You can tell by the explanation. It's
8:31
Speaker 2: interesting because it's become sufficiently rooted in popular consciousness. And
8:37
Speaker 2: this is a total turtle detail here, but one of
8:40
Speaker 2: the kinds of music I really like to listen to
8:42
Speaker 2: is a genre called symphonic metal, which is a bit bizarre.
8:46
Speaker 2: It's kind of operatic rock. If you think about the
8:49
Speaker 2: kind of stuff Queen we're doing, I'd go a little
8:52
Speaker 2: bit more rocky, a little bit more metal than that.
8:53
Speaker 2: It's like that, so you typically have an operatically trend
8:56
Speaker 2: soprano singing. The two biggest groups of that that I
9:00
Speaker 2: listened to quite a lot of groups called Nightwish and Epica.
9:04
Speaker 2: I might wish have done a couple of sigince sceened
9:05
Speaker 2: albums where they talk about the origin of life and
9:09
Speaker 2: philosophy and origin of species and all sorts of stuff.
9:12
Speaker 3: Like that.
9:12
Speaker 2: One of their tracks, which I try and get on
9:14
Speaker 2: the radio occasionally when I do a chat about asteroids,
9:17
Speaker 2: is a tribute to the great scientists Eugene Shoemaker, whose
9:21
Speaker 2: ashes were put onto a spacecraft to the moon, who
9:25
Speaker 2: discovered the comment that hit dup to back in nineteen
9:27
Speaker 2: ninety four. So that's might wish. But Epica have an
9:31
Speaker 2: album named the Holographic Principle, which they've always done slightly
9:36
Speaker 2: quirky projects as well. The fact that this concept, this
9:41
Speaker 2: thing that is at the very bound extreme bounds of
9:43
Speaker 2: theoretical physics and theoretical cosmology, has become sufficiently culturally embedded
9:50
Speaker 2: that rock groups and naming albums after it is kind
9:54
Speaker 2: of quirky for me. And it shows that it's not
9:58
Speaker 2: a totally brand new idea, because if it was certainly
10:00
Speaker 2: brand new, it wouldn't be in the popular consciousness. Yet
10:03
Speaker 2: it does make my head hurt. I will wholeheartedly and
10:07
Speaker 2: happily admit that this is not something where I'm an expert,
10:11
Speaker 2: you know, in any way, shape or form. There are
10:14
Speaker 2: very detailed discussions of it online. Even if you pull
10:17
Speaker 2: up the Wikipedia page. The Wikipedia page is pretty lengthy
10:22
Speaker 2: and links to a lot of references, talks about some
10:24
Speaker 2: of the discussions people have had about it, talks about
10:27
Speaker 2: information density, the people who've proposed all these ideas, and
10:31
Speaker 2: gives you links to other places. Now I know, certainly
10:34
Speaker 2: when I'm teaching, I have to tell people that Wikipedia
10:36
Speaker 2: is not the bill and end or it's a fluid resource.
10:40
Speaker 2: It's subject to change, and it's subject to being incorrect.
10:43
Speaker 2: But with a lot of these topics in the more
10:46
Speaker 2: theoretical parts of astrophysics or even fresterronomy as a whole,
10:49
Speaker 2: Wikipedia tends to be really pretty good because there's enough
10:52
Speaker 2: people out there who are really fascinated by the field
10:56
Speaker 2: that when they see something wrong, they'll fix it. The
10:58
Speaker 2: aerozont tend to hang around that one, so it tends
11:00
Speaker 2: to actually be a good first resource as long as
11:02
Speaker 2: it's not your only resource. And the article there about
11:05
Speaker 2: the holographic principle also links to these two albums by
11:09
Speaker 2: different groups that have had the same name that has
11:12
Speaker 2: a fairly lengthy discussion of a lot of the different
11:15
Speaker 2: ideas behind this, a few links to different types of
11:19
Speaker 2: theorems that are tied to this, and also a good
11:22
Speaker 2: list of twenty eight references and a couple of sources
11:25
Speaker 2: on top of that, including journal papers where if you
11:27
Speaker 2: really want to dive into this you can do will
11:31
Speaker 2: be very quickly apparent to you that by reading it
11:33
Speaker 2: to five minutes you already know more about it than
11:35
Speaker 2: I do. And then back to this sounds from point
11:38
Speaker 2: out every way in which I was wrong here, But
11:41
Speaker 2: that's my take on it. Now, with all that said,
11:45
Speaker 2: to get back to the question what do I think
11:46
Speaker 2: about the theory? I think I don't think about it
11:48
Speaker 2: very much because it makes my head hurt. But as
11:51
Speaker 2: I said, I think it gets to the point of philosophy.
11:53
Speaker 2: It's if there is something where you can make no
11:57
Speaker 2: testable measurement to differentiate between two different ideas, you're more
12:01
Speaker 2: in the bounds of philosophy than you are in the
12:03
Speaker 2: bounds of science. And it's a bit like that oldest
12:07
Speaker 2: of how do I know that anybody else actually exists?
12:09
Speaker 2: The only perception, the only existence I'm aware of is
12:13
Speaker 2: my own existence. I'm aware of my inner dialogue, and
12:16
Speaker 2: I'm aware of what I.
12:17
Speaker 1: See him perceive.
12:19
Speaker 2: And we implicitly assume that everybody we talk to is
12:22
Speaker 2: a being like us, but it could equally just be
12:25
Speaker 2: a convenient fiction. I could be entirely locked in my
12:28
Speaker 2: own head having all this is a kind of weird dream.
12:30
Speaker 2: I mean, I'd argue that this question is an example
12:33
Speaker 2: of the fact that I'm not just locking my own
12:35
Speaker 2: head and having a weird dream, because I would have
12:36
Speaker 2: never thought of this question myself. But you start getting
12:40
Speaker 2: to points where you are having an argument that is
12:44
Speaker 2: more one of philosophy than it is one of science.
12:47
Speaker 2: And for me, the thing that differentiates the two comes
12:50
Speaker 2: down to prediction and testing of theories. If you have
12:54
Speaker 2: a theory that is new, it should make testable predictions.
12:57
Speaker 2: And I'm not really sure because I'm not a theoretical
13:00
Speaker 2: cosmogis of theoretical physicist. If this doesn't, if it does,
13:04
Speaker 2: how they would work. So for me, then I come
13:07
Speaker 2: back to kind of the Okhams Raiser thing. With a
13:09
Speaker 2: lack of knowledge, with a lack of expertise. The simplest
13:12
Speaker 2: explanation to me is just that we are in the universe.
13:15
Speaker 2: We see but it's really fascinating to look into this.
13:18
Speaker 2: It's important to do this kind of work. I'm just
13:21
Speaker 2: not qualified to do it. I don't have the expertise.
13:23
Speaker 1: Yeah, it sort of connects with another theory that we
13:28
Speaker 1: have created this universe in our own minds as a collective,
13:34
Speaker 1: with the physical existence of the universe is a manifestation
13:37
Speaker 1: of us. Yeah, I've heard that one before, which is.
13:42
Speaker 2: An interesting one. Tied tow it is simulation theory, which
13:44
Speaker 2: I've also seen musical albums. Then after, which is the
13:47
Speaker 2: idea that what we live in is a simulation, and
13:49
Speaker 2: it's extrapolating off More's law and similar laws about computing
13:53
Speaker 2: power increasing into the future, which is that whilst the
13:57
Speaker 2: universe is infinitely complex, the amount of computing how you
14:00
Speaker 2: would need to fully simulate a universe is not as
14:03
Speaker 2: high as you would think, particularly if you set up
14:06
Speaker 2: your code so you only simulate the bits that of
14:08
Speaker 2: being observed at a time. Yeah, you don't need to
14:11
Speaker 2: For example, if you were simulating the Earth and everything,
14:13
Speaker 2: you wouldn't need to simulate the surface of these extra
14:16
Speaker 2: planets we've discovered yet because we don't have the ability
14:18
Speaker 2: to see them, so you save a huge amount in processing.
14:21
Speaker 2: So that leads to this argument that you could set
14:23
Speaker 2: up a simulation with their quality of fidelity that we
14:27
Speaker 2: couldn't know the difference. Simulation theory then goes to one
14:31
Speaker 2: step further and says, if you can do that once,
14:33
Speaker 2: it's only a small step from being able to do
14:35
Speaker 2: something once to being able to do it many, many times.
14:38
Speaker 2: So therefore, statistically it becomes more likely that we live
14:41
Speaker 2: in a simulation rather than the real world, because there'll
14:44
Speaker 2: be millions of universes and only one of them will
14:46
Speaker 2: be real. And it's fascinating, it's really good fun. But
14:48
Speaker 2: again it's philosophy, because how do we test this unless
14:52
Speaker 2: we get to take the pill and step out of
14:54
Speaker 2: the matrix and see it for what it is. How
14:57
Speaker 2: you test between these things is really the child for
15:00
Speaker 2: me to make them into a really scientificness gosh, rather
15:03
Speaker 2: than philosophicalword.
15:05
Speaker 1: Yeah, the Matrix was a good film in a constructed
15:10
Speaker 1: universe and the reality was much more horrifying. But yeah,
15:15
Speaker 1: great question, and yeah, I think that's one that will
15:18
Speaker 1: be debated for years to come. Thanks Charles. This is
15:22
Speaker 1: Space Nuts Andrew Dunkley here with Professor John T. Horna.
15:27
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17:22
Speaker 1: Now back to the show Space Nuts. Okay, Johnny, let's
17:29
Speaker 1: do some audio questions. And this one I thought we'd done,
17:32
Speaker 1: but I remember I did send it to you in name,
17:36
Speaker 1: but I sent you the wrong audio, so we did
17:38
Speaker 1: the other one. And so this is the question I
17:40
Speaker 1: meant to send you a couple of weeks ago from David.
17:43
Speaker 3: This is David from zagein Texas. I've got another question
17:47
Speaker 3: about Black Halls, just like all my other questions. I
17:50
Speaker 3: was listening to the latest episode and you were talking
17:52
Speaker 3: about late spinning around black Halls, and I was being
17:58
Speaker 3: able to see the f facts later than when the
18:01
Speaker 3: event actually happened. But that got me thinking, if the
18:07
Speaker 3: light goes around a black hole and then it starts
18:10
Speaker 3: to slowly get sucked in, would the additional gravity of
18:15
Speaker 3: the black hole pulling on the light increase the speed
18:19
Speaker 3: of the light any faster than the speed of light.
18:21
Speaker 2: Or even at all?
18:23
Speaker 3: Because I know when a ballet dancer is spinning and
18:25
Speaker 3: she pulls her arms in, she spins faster. So would
18:29
Speaker 3: that effect be the same on light spinning around the
18:33
Speaker 3: black hole and then getting sucked in. I'm not really
18:37
Speaker 3: sure how that works with light, considering it has no mass,
18:41
Speaker 3: but I appreciate if you answer my question.
18:43
Speaker 1: Thank you. Good on you, David. I'm pretty sure ballerinas
18:47
Speaker 1: don't spin at the speed of light, but could be wrong.
18:52
Speaker 1: They do spin rather remarkably. Yeah, look, this is an
18:55
Speaker 1: interesting one. Light is the fastest thing in the universe,
19:00
Speaker 1: so I venture to say, and I think in conversations
19:05
Speaker 1: Fred and I have had in the past that nothing
19:07
Speaker 1: goes faster than the speed of light in a vacuum.
19:11
Speaker 1: So I would imagine the answer is probably know that
19:15
Speaker 1: the black hole can't make light go faster than the
19:17
Speaker 1: speed of light.
19:19
Speaker 2: It doesn't change the speed of light, it changes its direction.
19:23
Speaker 2: If you change the energy of light, because you can't
19:28
Speaker 2: change the speed, what you change is the frequency of
19:30
Speaker 2: the way of length. So if light is trying to
19:33
Speaker 2: escape from a mass, then you see a thing called
19:37
Speaker 2: gravitational redshift. So light coming up from the surface of
19:41
Speaker 2: the Sun will be red shifted at tony a little
19:44
Speaker 2: bit because it's escaping from the gravitational well of the Sun. Similarly,
19:48
Speaker 2: if it was falling inwards, so you expected to be
19:49
Speaker 2: slightly blue shifted. But it's a very very small and
19:52
Speaker 2: perceptible thing in terms of the speed of light being
19:55
Speaker 2: the fastest thing there results where all our models of
19:58
Speaker 2: the universe and everything's set. And Terry Pratchett, in one
20:02
Speaker 2: of the many discworld books that I love very well,
20:04
Speaker 2: made the point that darkness must travel faster than light.
20:08
Speaker 2: It's whenever you turn on a light, it was already dark.
20:11
Speaker 2: I think it's quite nice and poetic. But in reality
20:15
Speaker 2: it seems that the speed of light in all the
20:17
Speaker 2: models we have of the investent cosmologies is kind of
20:20
Speaker 2: inviolable speed limit of the universe. Now, it might be
20:24
Speaker 2: that when we have a chat in twenty years time
20:26
Speaker 2: that a change to tally, because that's how science works.
20:30
Speaker 2: But at the minute, the speed of light is a
20:32
Speaker 2: speed of light, and there is an implicit thing there
20:35
Speaker 2: that we never mentioned that we should do that. What
20:37
Speaker 2: we're actually talking about there is the speed of the
20:39
Speaker 2: light in the vacuum space. Yeah, so as soon as
20:42
Speaker 2: the light passes into a medium, it slows down, and
20:44
Speaker 2: that's why you get refraction. If light goes from air
20:48
Speaker 2: into water, the speed of light in water is slower
20:51
Speaker 2: than the speed of light in air. That's why you
20:53
Speaker 2: get the bending, the change of direction there. With black holes,
20:57
Speaker 2: what's actually happening is that the black hole bending space,
21:01
Speaker 2: and the light is following a straight path on a
21:03
Speaker 2: curved surface, so it appears to bend, which is subtly different.
21:08
Speaker 2: Essentially light falling into a black hole. If you could
21:11
Speaker 2: imagine being just outside the event horizon, so you're not
21:15
Speaker 2: dead and you're looking outwards, the things you were looking
21:19
Speaker 2: at would look a little bit bluer than they actually are,
21:22
Speaker 2: because light falling in is getting blue shifted as it
21:24
Speaker 2: comes towards you. Similarly, if you shone a yellow light
21:29
Speaker 2: or a green light laser, I've got one of those.
21:31
Speaker 2: When I do outreach sometimes to point the stars out.
21:34
Speaker 2: If I shown a green light laser out from near
21:36
Speaker 2: the event horizon of the black hole. The light would
21:38
Speaker 2: sile escape with some outside the event horizon, so they
21:41
Speaker 2: escape loss is lower than the sweed of light. There's
21:44
Speaker 2: an acceleration pulling back. The speed of the light cannot change,
21:48
Speaker 2: but the energy would change, so it would become gravitationally
21:51
Speaker 2: red shifted, so that green light laser would look redder
21:55
Speaker 2: to the observer where beyond the black hole than it
21:58
Speaker 2: would as it leaves in my hand where I'm in
22:00
Speaker 2: the shaddress frame for that. But the speed of light
22:03
Speaker 2: itself would not be changing caveat if the black hole's
22:07
Speaker 2: got a disc of material around it. If it's got
22:09
Speaker 2: material around it, then you're not moving through a perfect vacuum.
22:12
Speaker 2: So you would see a little bit of a change
22:14
Speaker 2: in speed there. But that is a different physical process
22:18
Speaker 2: for a different reason. But it's worth being complete.
22:22
Speaker 1: I guess, yes, Yes, I suppose. The other interesting thing
22:25
Speaker 1: about light, which we've talked about before, is that, as
22:28
Speaker 1: you said, it slows down in liquid, but light going
22:32
Speaker 1: through a glass slows down, but when it comes out
22:34
Speaker 1: the other side it speeds up again. Yes, and that's
22:37
Speaker 1: like the other direction. Yeah, yeah, So it's a tricky
22:42
Speaker 1: thing light because we take it for granted, we need it.
22:45
Speaker 1: It's something we've adapted to on this planet as human beings.
22:50
Speaker 1: If we would have venture to another planet with a
22:52
Speaker 1: different kind of star, it would be alien to us
22:57
Speaker 1: in more ways than we could imagine, because we are
23:01
Speaker 1: used to a medium sized star with a relatively right light.
23:06
Speaker 1: But if you went to a planet with a I
23:08
Speaker 1: don't know, a blue star, a bright blue star, the
23:13
Speaker 1: vegetation to be a different color because it would be
23:16
Speaker 1: having to do a different kind of photosynthesis. You'd see
23:20
Speaker 1: things differently. You know, there's all sorts of weird and
23:24
Speaker 1: wonderful things that light could do in other places. Just
23:28
Speaker 1: theory at the moment, but action.
23:32
Speaker 2: I've seen these articles about a small subset of women
23:36
Speaker 2: who have an extra set of cells detecting color in
23:39
Speaker 2: their eye, which gives them an incredibly more granular and
23:42
Speaker 2: fine ability to differentiate colors, so the visual equivalent of supertesters,
23:48
Speaker 2: and they can see something that to you or eye
23:51
Speaker 2: would just look like it's cirticle.
23:53
Speaker 1: And they can see the hues within that.
23:55
Speaker 2: Equally, you see these beautiful images of birds that look
23:58
Speaker 2: very dune and boring, to us, but then you see
24:01
Speaker 2: a visualization of what they would look like to one
24:03
Speaker 2: of the bird and they're incredibly colorful and vibrant because
24:05
Speaker 2: the birds are seeing frequencies that our eyes are not
24:09
Speaker 2: accustomed to. Similarly with bees and things like that, seeing
24:12
Speaker 2: into the ultra violet, and that will be accentuated for
24:16
Speaker 2: objects around, you know, planets, around the stars. You then
24:20
Speaker 2: get the other ties. I have had the pleasure of
24:23
Speaker 2: seeing a couple of total eclipses of the Sun, one
24:25
Speaker 2: of which I didn't actually see because it was cloudy
24:27
Speaker 2: and Cairnes in twenty twelve, but we saw the build
24:29
Speaker 2: up in the aftermath and the eclipse itself so soon.
24:33
Speaker 2: But there's this very weird Uncammi Valley period in the
24:36
Speaker 2: minutes just before and the minutes just after totality, where
24:39
Speaker 2: the Sun is a tiny little point because most of
24:42
Speaker 2: it's blocked by the Moon. So instead of having a disc,
24:45
Speaker 2: the Sun gets smaller and smaller until we've essentially got
24:47
Speaker 2: a single point of light shining nearly as bright as
24:49
Speaker 2: the sun, and shadows change and the behavior of shadows
24:53
Speaker 2: look different when you've got a single point, so rather
24:56
Speaker 2: than a few sorts of light, and that gives everything
24:59
Speaker 2: a very uncomfortable, slightly unusual feeling. You've got very cool
25:04
Speaker 2: effects like standing under a tree and all the leaves
25:07
Speaker 2: are blowing and all the gaps between the leaves act
25:10
Speaker 2: as pinhole cameras and you get images of the crescent
25:12
Speaker 2: Sun on the ground, which is spectacular.
25:14
Speaker 1: Wow.
25:15
Speaker 2: Incidentally, on the eclipse trip I went to for the
25:19
Speaker 2: Xmouth eclipse, a lot of people have a little pinhole
25:22
Speaker 2: cameras that they made to women's eclipse, and one person
25:25
Speaker 2: had a pack of jats, which are just an Australian
25:28
Speaker 2: cheese biscuit, and the poles in the biscuits were perfect
25:31
Speaker 2: pinhole cameras, and they had a snack, so when the
25:35
Speaker 2: eclips finished, nobody was hungry. It was absolutely brilliant and
25:38
Speaker 2: I'd never even thought of it, so you get all
25:41
Speaker 2: these weird effects in it. We take for granted very
25:44
Speaker 2: very much that our perception is actually what is out there,
25:48
Speaker 2: and this was brought home to me. I went to
25:51
Speaker 2: driving range with one of my PhD students. Obviously I
25:54
Speaker 2: don't play golf, and I'm particularly bad at it, but
25:56
Speaker 2: there's always this thing about what you perceive and how
25:59
Speaker 2: much of the area of your vision that you're actually
26:01
Speaker 2: actively updating, and how much of it is just auto
26:03
Speaker 2: generated by your brain best on all the information and
26:07
Speaker 2: you forget about that. But we actually are like our
26:09
Speaker 2: eyes are rastering across and we only see a tiny
26:11
Speaker 2: little bit of our vision. Are we seeing true updates?
26:14
Speaker 2: And I've never really seen that demonstrated. And sois at
26:17
Speaker 2: the driving range, because if I hit a golf ball,
26:20
Speaker 2: and I often hit them very badly, but they go
26:22
Speaker 2: up in the air somewhere, and I can stand there
26:24
Speaker 2: and watch where it goes, and it's easy, and you
26:26
Speaker 2: can follow it all the way. The minute you look
26:29
Speaker 2: away and look back, you cannot find the ball exactly.
26:32
Speaker 2: It's astonishing, and you think when you're just looking at
26:35
Speaker 2: it's really obvious there's a ball. There is the yellow
26:38
Speaker 2: or white against the blue sky that target more obvious.
26:41
Speaker 2: Look away, totally lost it, even if you know where
26:43
Speaker 2: it was. And that's all down to how our brain
26:47
Speaker 2: is processing the day to were getting the ball is
26:49
Speaker 2: still there. The ball hasn't miraculously disappeared, and so all
26:53
Speaker 2: these kind of questions. I find it really fascinating that
26:56
Speaker 2: boundary between the perception of the reality and I wonder
26:59
Speaker 2: what we observe is of our own generation essentially.
27:03
Speaker 1: Yeah, it reminds me of that famous gorilla experiment. You're
27:06
Speaker 1: aware of that one. Yeah, that that is a very
27:11
Speaker 1: great It's a great example of what you think you
27:15
Speaker 1: see and what's really there. And I won't try and
27:19
Speaker 1: spoil it for anybody. You can see it on YouTube videos.
27:22
Speaker 2: Yeah, they do that in a lot of training for
27:25
Speaker 2: things like police officers, to talk about the funt that
27:28
Speaker 2: people who think they've witnessed something are inherently unreliable. And
27:32
Speaker 2: it's also what makes it very feasible for magicians and
27:36
Speaker 2: concerts and tricksters to trick you by taking your brain
27:41
Speaker 2: off somewhere else. You know. The whole slight of hump
27:43
Speaker 2: thing is all bother of this thing.
27:45
Speaker 1: Yeah, it's really remarkable. I could talk about this stuff forever.
27:49
Speaker 1: I really think that it's fascinating. But yeah, lovely question, David,
27:53
Speaker 1: and I hope that it covered you adequately as we
27:57
Speaker 1: strive to do here on space nuts. But no, black
27:59
Speaker 1: hole can't make light travel faster than light.
28:07
Speaker 2: Space nuts.
28:08
Speaker 1: Our final question comes from a regular cender in arat
28:11
Speaker 1: from the United Kingdom. Below.
28:14
Speaker 4: It is Duncan from Weymouth, in the UK yere again,
28:20
Speaker 4: just wondering is it possible to have an exoplanet that
28:23
Speaker 4: is entirely liquid, so it could just be like a
28:29
Speaker 4: global ocean, but with no solid core, just liquid all
28:34
Speaker 4: the way through. If it's not possible and it has
28:38
Speaker 4: to have a solid core, why is that?
28:42
Speaker 1: And also.
28:44
Speaker 4: How small could that solid core be?
28:47
Speaker 1: Could it be.
28:49
Speaker 4: Something the size of say Everest, or could it be
28:54
Speaker 4: even smaller or does it have to be something bigger,
28:58
Speaker 4: maybe the size of the moon. I don't know what
29:02
Speaker 4: are your thoughts on that and opinions?
29:05
Speaker 2: Do you have any actual answers?
29:07
Speaker 1: Does anyone know?
29:09
Speaker 4: Just wondering, prouds you could give us some answers with
29:13
Speaker 4: regards to that.
29:15
Speaker 1: Okay, thank you very much, keep up good work.
29:21
Speaker 4: And well until next time.
29:23
Speaker 1: Thank you, Duncan. I love this question because these are
29:26
Speaker 1: the sorts of things I wonder. And look, we've got
29:29
Speaker 1: examples of ice worlds in our Solar system. They are
29:33
Speaker 1: ice moons that they have a solid surface, and it's
29:36
Speaker 1: thought that they probably have a solid core, but in
29:38
Speaker 1: between oceans. But he's talking about an exoplanet that is
29:43
Speaker 1: pure liquid, just a big blob of water.
29:46
Speaker 2: Yes, it's a fabulous question, and again this can have
29:51
Speaker 2: a shot answering the one answer. The short answer is
29:54
Speaker 2: essentially no, but it's not for the reason you're thinking of.
29:57
Speaker 2: It's not to do with the car. It's a fact
29:59
Speaker 2: that must can be a liquid, and I'm aware of
30:01
Speaker 2: in the vacuum of space, so one of the surface
30:04
Speaker 2: of the liquid you will get evaporation and you would
30:06
Speaker 2: end up with an atmosphere, so you'd end up with
30:08
Speaker 2: a guessious shroud around it doesn't need to be much atmosphere,
30:11
Speaker 2: So technically it couldn't be entirely liquid because it would
30:14
Speaker 2: need to be gas around it for there to be
30:16
Speaker 2: sufficient pressure that the material on the surface can remain liquid.
30:21
Speaker 2: You could create something, of course, but you'd need it
30:23
Speaker 2: like a bubble around it, glass shell or whatever. The
30:27
Speaker 2: other reason that in a physical sense it would be
30:30
Speaker 2: very unlikely to have this is that the things that
30:34
Speaker 2: you form are made of everything that's around. Rocky planets
30:39
Speaker 2: don't capture the hydrogen and healingxerescape ve loss is too high,
30:42
Speaker 2: so the gravity is too weak. But when you're forming something,
30:46
Speaker 2: you're building a planet, you're building in of everything that
30:48
Speaker 2: is around, so that will include a lot of water
30:51
Speaker 2: if you're somewhere where the temperature is low enough fur
30:53
Speaker 2: water to become an icon to be a solid, but
30:55
Speaker 2: it will also include iron and nickel and dust and
30:58
Speaker 2: all the other stuff, And you're not going to have
31:01
Speaker 2: a situation where everything you form a planet from would
31:06
Speaker 2: all be liquid at the same conditions, so you'd always
31:09
Speaker 2: end up with some stuff sinking to the middle of solids.
31:13
Speaker 2: What you could imagine, though, is you could have a
31:16
Speaker 2: idealized situation. Let's say you could quarantine an area of
31:19
Speaker 2: space off and you could form something planet mass out
31:24
Speaker 2: of absolutely perfectly pure water ice so and nothing else
31:28
Speaker 2: but hydrogen and oxygen bound together. In that scenario, I
31:32
Speaker 2: could imagine you having a planet that is almost entirely
31:35
Speaker 2: liquid except for the atmosphere, which will be water vapor
31:40
Speaker 2: and would probably then quickly become an oxygen rich atmosphere
31:42
Speaker 2: because once you've got water vapor exposed to UV, it
31:46
Speaker 2: gets dissociated in hydrogen and oxygen blah blah blah that
31:49
Speaker 2: fappens there. You would then have a situation where, depending
31:55
Speaker 2: on the mass of the object, you could have an
31:59
Speaker 2: object liquid all the way through. If the object is
32:01
Speaker 2: too lower mass, you'd gradually lose it because if it's
32:06
Speaker 2: a low enough mass and it's going around the star,
32:08
Speaker 2: the stuff that's boiling off former gas will then be
32:12
Speaker 2: moving fast enough to escape, so the atmosphere will be
32:14
Speaker 2: stripped and the thing will essentially boil away, like if
32:16
Speaker 2: you leave a pan on the hob. I would imagine
32:19
Speaker 2: that there is also a range of sizes and masses
32:23
Speaker 2: where the pressure in the center gets so high that
32:25
Speaker 2: the water becomes ice again, even at high temperature, and
32:29
Speaker 2: we see this with Urinus and Nettune. There is certainly
32:31
Speaker 2: water ice in the interior of those, but it's a
32:34
Speaker 2: different phase of water ice to that we used, so
32:37
Speaker 2: I never really understood this. But there is an incredibly
32:39
Speaker 2: gifted Australian researcher called Helen maynad Caseley who last time
32:44
Speaker 2: I've not seen her for a few years, but she
32:46
Speaker 2: used to work down an anstole at in northern Sydney
32:50
Speaker 2: using devices like one bat doing X ray diffraction and
32:53
Speaker 2: stuff like this, and she discovered several new types of
32:57
Speaker 2: water ice because she was looking at what happens to
32:59
Speaker 2: water are temperatures and pressures very different to room temperature,
33:04
Speaker 2: and that can be really cold conditions lack on the
33:06
Speaker 2: icimins of Jupiter, or it can be really high pressures
33:09
Speaker 2: or both. And so it's fairly well established that if
33:12
Speaker 2: you increase the pressure water ice will remain solid at
33:16
Speaker 2: higher temperatures. That this boiling at one hundred and freezing
33:20
Speaker 2: at zero is a function of the current atmosphere pressure
33:24
Speaker 2: we have on Earth, and you change that and it changes. Yeah. Incidentally,
33:27
Speaker 2: that's why if you're a bit of a tea fishing idol,
33:30
Speaker 2: you cannot get a good cup of tea at high
33:31
Speaker 2: altitude because water boils are a low enough temperature that
33:35
Speaker 2: it makes them a cup of tea. You know. But
33:37
Speaker 2: people who went into the Himalayas grumbling about how terrible
33:40
Speaker 2: the tea was, and you're at high in altitude that
33:42
Speaker 2: the boiling point of water is reduced enough that and
33:47
Speaker 2: for people listening in America who aren't familiar with this,
33:49
Speaker 2: people particularly from the UK, are very obsessive about their tea.
33:53
Speaker 2: But to make tea you need the water to be
33:54
Speaker 2: on a rolling boil at one hundred degrees c. Well
33:58
Speaker 2: for many kinds of black teas, green tea, and white
34:00
Speaker 2: t it's called the temperature. But when you make tea
34:03
Speaker 2: with lukewarm water. That is wrong. That just doesn't work,
34:07
Speaker 2: and you get a very different behavior. And it's to
34:09
Speaker 2: do with the chemistry of what goes on.
34:12
Speaker 1: Yeah, that's fascinating.
34:14
Speaker 2: Yeah, comes into this mm HM, which would ly to
34:18
Speaker 2: if we ever found a planet that was pure water
34:21
Speaker 2: and was liquid all the way through, that to me
34:23
Speaker 2: will be evidence of the builders of Magra, thea from
34:26
Speaker 2: double Sadoms, you know, it would be evidence that this
34:28
Speaker 2: was a constructed entity rather than something that form naturally.
34:31
Speaker 1: Bis.
34:32
Speaker 2: The contamination is the simplest way of saying you wouldn't
34:34
Speaker 2: get a purely liquid planet. You can get a planet
34:36
Speaker 2: that is more liquid than anything else. And we have
34:39
Speaker 2: suspicions that there are these high seeing worlds its ocean planets,
34:43
Speaker 2: and the reasoning there is that water is actually one
34:46
Speaker 2: of the most common things in the universe. You've got
34:48
Speaker 2: the most common atom with hydrogen, You've got the third
34:50
Speaker 2: mass common atom with oxygen. You put them together, you
34:52
Speaker 2: get water, ice or liquid water or water vapor. So
34:56
Speaker 2: you can imagine planets that have more water than anything else,
34:59
Speaker 2: that are a huge oceans with a coal underneath them
35:03
Speaker 2: that are ice and then liquid and ic again like
35:06
Speaker 2: we see without the moves, but getting something that is
35:08
Speaker 2: liquid from the surface to the car has those problems,
35:11
Speaker 2: one of contamination, one of you would need an atmosphere
35:14
Speaker 2: to have the pressure to remain liquid.
35:17
Speaker 1: Fascinating. Yeah, I love that question, Duncan. So the answer
35:20
Speaker 1: is probably no, but not far off in some respects.
35:24
Speaker 1: But it might take a megastructure of some kind to
35:29
Speaker 1: create a water world, although Kevin Costner did find one apparently,
35:34
Speaker 1: but only the.
35:34
Speaker 2: Costs of going that film the film We're outrageous.
35:37
Speaker 1: So yes, yes, yes they're trying to get it all
35:39
Speaker 1: back with a theme park, I think, but yes, Thank
35:42
Speaker 1: you Duncan. Always good to hear from you. You've always
35:45
Speaker 1: got some great ideas and if you would like to
35:47
Speaker 1: send us some questions please do via our website, space
35:50
Speaker 1: nuts podcast dot com, space nuts dot io and have
35:53
Speaker 1: a look around while you're there. Check out the shop,
35:55
Speaker 1: check out out around all the other things, and don't
35:58
Speaker 1: forget to click the AMA at the top, which is
36:00
Speaker 1: where you send your questions text or audio versions. Thank you, Johnny,
36:05
Speaker 1: that was great fun.
36:06
Speaker 2: It's a pleasure. It's always good to start. Thank you
36:08
Speaker 2: for having me.
36:09
Speaker 1: Oh no, my pleasure. We'll catch up with you next time.
36:12
Speaker 1: Professor John T. Horner from the University of Southern Queensland.
36:16
Speaker 2: Hugh couldn't be.
36:17
Speaker 1: With us today. I don't know what he's been up to,
36:19
Speaker 1: but I do know about today. Apparently he was using
36:22
Speaker 1: a telescope to try and see his own reflection. He's
36:26
Speaker 1: still going. He's been doing it for days apparently. And
36:29
Speaker 1: from me Andrew Uncley, thanks for your company. Catch you
36:31
Speaker 1: on the very next episode of Space Nuts. Bye bye.
36:35
Speaker 2: You'll be listening to the Space Nuts podcast available at
36:40
Speaker 2: Apple Podcasts, Spotify, iHeartRadio, or your favorite podcast player.
36:45
Speaker 1: You can also stream on demand at bides dot com.
36:49
Speaker 4: This has been another quality podcast production from nights dot Com.