Episode Highlights:
- The Evolution of Exoplanet Discovery: Andrew and Jonty discuss the advancements in technology that have allowed astronomers to discover thousands of exoplanets, with a particular focus on Earth-like planets that could potentially harbour life.
- The Challenges of Finding Life: The hosts address the difficulties in the search for extraterrestrial life, including the implications of the absence of evidence and the complexities of distinguishing between life forms.
- Life in Our Solar System: Jonty shares insights on why we might find life within our solar system, particularly on Mars and the icy moons of the outer planets, and how robotic exploration is key to this search.
- Defining Habitable Zones: The conversation shifts to the criteria that define a habitable zone around stars and the importance of factors such as stellar type, distance, and planetary characteristics in the search for life.
- Philosophical Implications: The hosts ponder the philosophical questions surrounding the existence of life and the potential for advanced civilisations, and whether humanity is prepared for contact with extraterrestrial intelligence.
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Stay curious, keep looking up, and join us next time for more stellar insights and cosmic wonders. Until then, clear skies and happy stargazing.
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Chapters:
- Introduction to Astrobiology
- Technological Advances in Exoplanet Discovery
- Searching for Life in Our Solar System
- Defining Habitable Zones and Their Importance
- The Philosophical Questions of Extraterrestrial Life
00:00:00 --> 00:00:00 Jonti Horner: Hi there.
00:00:00 --> 00:00:02 Andrew Dunkley: Thanks for joining us again. This is Space
00:00:02 --> 00:00:05 Nuts, where we talk astronomy and space
00:00:06 --> 00:00:08 science. And my name is Andrew Dunkley, your
00:00:08 --> 00:00:10 host. Great to have your company. Now,
00:00:10 --> 00:00:12 normally I'd be joined by Professor
00:00:12 --> 00:00:14 Fred Watson Watson, but he is away, uh,
00:00:14 --> 00:00:17 visiting family at the moment. And because he
00:00:17 --> 00:00:19 was going to be away and then I'm going to be
00:00:19 --> 00:00:21 away and we tried to cram episodes in and,
00:00:21 --> 00:00:24 uh, we just couldn't do enough in the amount
00:00:24 --> 00:00:26 of time we had. Uh, we invited Professor
00:00:26 --> 00:00:29 Jonty Horner to join us and we're, uh, going
00:00:29 --> 00:00:30 to do some specials. You might have heard the
00:00:30 --> 00:00:33 last one, uh, which was very engaging
00:00:33 --> 00:00:36 and interesting and fascinating and long. Uh,
00:00:36 --> 00:00:39 this time we, we're going down a different
00:00:39 --> 00:00:40 road. We're going to focus the whole
00:00:40 --> 00:00:41 programme on
00:00:41 --> 00:00:44 astrobiology. Strap in.
00:00:44 --> 00:00:47 We'll do that right now. 15 seconds.
00:00:47 --> 00:00:49 Guidance is internal. 10,
00:00:50 --> 00:00:52 9. Ignition sequence.
00:00:52 --> 00:00:55 Jonti Horner: Star. Space nuts. 5, 4, 3, 2.
00:00:55 --> 00:00:58 Andrew Dunkley: 1. 2, 3, 4, 5, 5, 4, 3,
00:00:58 --> 00:00:58 2, 1.
00:00:58 --> 00:01:00 Jonti Horner: Space nuts.
00:01:00 --> 00:01:02 Andrew Dunkley: Astronauts report it feels good. And here he
00:01:02 --> 00:01:05 is again, professor of astrophysics at the
00:01:05 --> 00:01:07 University of Southern Queensland, Johnty
00:01:07 --> 00:01:09 Horner. G', day, Johnty G'.
00:01:09 --> 00:01:09 Jonti Horner: Day. How are you going?
00:01:09 --> 00:01:11 Andrew Dunkley: I'm well. Good to see you again.
00:01:12 --> 00:01:14 And, uh, we've got a lot to talk about, so I
00:01:14 --> 00:01:16 think we're going to just dive on in.
00:01:16 --> 00:01:19 Now, in preparation for this astrobiology
00:01:19 --> 00:01:21 chat, you sent me a paper that you wrote,
00:01:22 --> 00:01:24 uh, and published on the Arxiv website.
00:01:25 --> 00:01:28 Uh, it's, um, ancient.
00:01:28 --> 00:01:31 Yeah, it's, it's coming up on 16
00:01:31 --> 00:01:33 years since you wrote that. But one of the
00:01:33 --> 00:01:36 interesting parts was, um, look, it's
00:01:36 --> 00:01:38 been a couple of decades now that we've been
00:01:38 --> 00:01:40 finding exoplanets. And as technology
00:01:40 --> 00:01:43 improves, it's only a matter of time before
00:01:43 --> 00:01:45 we start finding Earth like planets. And
00:01:45 --> 00:01:48 that's really going to make the search for
00:01:48 --> 00:01:51 life beyond our solar system really,
00:01:51 --> 00:01:54 really interesting. So those 16 years have
00:01:54 --> 00:01:55 passed. Have we got the. Have we got the
00:01:55 --> 00:01:57 equipment yet? I suspect we have.
00:01:58 --> 00:02:00 Jonti Horner: It depends where you're looking, I think. I
00:02:00 --> 00:02:02 mean in terms of looking at the planet. Round
00:02:02 --> 00:02:05 of the stars. We can now learn a lot more
00:02:05 --> 00:02:07 about them than we could 16 years ago when I
00:02:07 --> 00:02:10 wrote the paper, that particular paper. But
00:02:10 --> 00:02:12 we're still not there yet. And it's a
00:02:12 --> 00:02:15 perpetual thing. No matter how hard you work,
00:02:15 --> 00:02:17 there's always more to do. The other thing
00:02:17 --> 00:02:19 that goes along with it, which I think is
00:02:19 --> 00:02:21 worth saying right up at the very start, is,
00:02:21 --> 00:02:24 uh, searching fly false worries going to be
00:02:24 --> 00:02:25 one of the hardest things we've ever done.
00:02:26 --> 00:02:28 And, um, absence of evidence is not
00:02:28 --> 00:02:31 necessarily evidence of absence.
00:02:31 --> 00:02:34 What I mean by that is we could, in a
00:02:34 --> 00:02:36 remarkable turn of events in the next few
00:02:36 --> 00:02:38 months, find life elsewhere. You know, that's
00:02:38 --> 00:02:40 kind of the ultimate extreme, soonest
00:02:40 --> 00:02:43 possible. Um, very unlikely to happen.
00:02:43 --> 00:02:45 Alternatively, we might still be looking in a
00:02:45 --> 00:02:48 century. If we're still looking in a century.
00:02:49 --> 00:02:51 That doesn't mean that there isn't any life
00:02:51 --> 00:02:53 out out there, but what it will suggest
00:02:53 --> 00:02:56 to us is that life is relatively scarce.
00:02:56 --> 00:02:59 So to me, the sooner we find life elsewhere,
00:03:00 --> 00:03:02 that 8 will be awesome. Because, hey, look,
00:03:02 --> 00:03:03 we found life elsewhere, and we've answered
00:03:03 --> 00:03:06 the ultimate question, are we alone? But the
00:03:06 --> 00:03:07 sooner we find life elsewhere, the other
00:03:07 --> 00:03:09 thing it's telling us is that life must be
00:03:09 --> 00:03:11 fairly common in the universe. The scarcer
00:03:11 --> 00:03:14 life is, the harder it will be to find, and
00:03:14 --> 00:03:16 therefore the longer it will take us to find.
00:03:16 --> 00:03:18 And now the ultimate extreme of that is that,
00:03:19 --> 00:03:20 uh, this is the only place that there is
00:03:20 --> 00:03:23 life. And it'll be very hard
00:03:23 --> 00:03:26 to conclude that even if we were talking
00:03:26 --> 00:03:28 through a time warp, in 10 years, when
00:03:28 --> 00:03:30 humanity is taking its fledgling steps into
00:03:30 --> 00:03:33 the galaxy or whatever, if we haven't found
00:03:33 --> 00:03:35 life by then, we'll be confident that life is
00:03:35 --> 00:03:38 very rare and very precious. That doesn't
00:03:38 --> 00:03:40 mean that there is not life somewhere else in
00:03:40 --> 00:03:42 the universe. And it's one of the challenges
00:03:42 --> 00:03:44 with this. I would like to think that we'll
00:03:44 --> 00:03:45 find the answer to that question in our
00:03:45 --> 00:03:48 lifetime. But the only way we'll get an
00:03:48 --> 00:03:49 answer to the question, are we alone, um,
00:03:50 --> 00:03:52 within our lifetime? As if the answer is no,
00:03:52 --> 00:03:54 if that answer is that there is life
00:03:54 --> 00:03:56 elsewhere. And this is one of the big,
00:03:57 --> 00:03:59 really, really big open questions for
00:03:59 --> 00:04:01 humanity, open questions for science. You
00:04:01 --> 00:04:03 know, when I was a kid, when you were a kid,
00:04:03 --> 00:04:05 one of the big questions was, is the solar
00:04:05 --> 00:04:07 system unique? Or are there planets around
00:04:07 --> 00:04:09 other stars? And we'll talk about that more
00:04:09 --> 00:04:12 in the next episode. But there is nobody
00:04:12 --> 00:04:15 under the age of 30, 31 alive on
00:04:15 --> 00:04:16 this planet that grew up in that shared
00:04:16 --> 00:04:18 universe with you and I. So that fundamental
00:04:18 --> 00:04:21 question got answered and answered in ab.
00:04:22 --> 00:04:24 And answering that question is the first real
00:04:24 --> 00:04:26 step to say, is there life elsewhere
00:04:26 --> 00:04:29 beyond the solar system? Because in order to
00:04:29 --> 00:04:32 find life beyond the solar system, we first
00:04:32 --> 00:04:33 need to know that there's somewhere that life
00:04:33 --> 00:04:36 could exist. The question of life in the
00:04:36 --> 00:04:37 solar system is a different one. And that's
00:04:37 --> 00:04:39 all part of astrobiology. So if you bundle
00:04:39 --> 00:04:42 all of this together, that question of how we
00:04:42 --> 00:04:44 alone, um, is there life elsewhere? Which
00:04:44 --> 00:04:46 brings with it Questions like, what is the
00:04:46 --> 00:04:48 origin of life, why are we here? How did life
00:04:48 --> 00:04:50 begin, how did it get established, what are
00:04:50 --> 00:04:53 the processes needed? Everything like that,
00:04:53 --> 00:04:54 yeah, is what gets bundled in, in
00:04:54 --> 00:04:57 astrobiology. And astrobiology is a very,
00:04:57 --> 00:05:00 very weird science. I know certainly early in
00:05:00 --> 00:05:02 my career, a lot of older scientists viewed
00:05:02 --> 00:05:05 astrobiology in a similar way to the way a
00:05:05 --> 00:05:07 lot of astronomers view astrology almost. You
00:05:07 --> 00:05:09 know, they viewed it as being speculation,
00:05:09 --> 00:05:12 fiction and hook, you know, total bogus waste
00:05:12 --> 00:05:15 of time stuff. But it really isn't.
00:05:16 --> 00:05:18 Yeah, but one of the real challenges is, uh,
00:05:18 --> 00:05:20 it's not a question that one single
00:05:20 --> 00:05:22 discipline on its own can answer. Right. It's
00:05:22 --> 00:05:24 not like in astronomy, you, you're studying
00:05:24 --> 00:05:27 how, so you talk to astronomers in
00:05:27 --> 00:05:30 astrobiology, if we're looking at everything
00:05:30 --> 00:05:33 to do with life, astronomers like myself
00:05:33 --> 00:05:35 can't do it on their own, biologists can't do
00:05:35 --> 00:05:38 it on their own. You need geophysicists, you
00:05:38 --> 00:05:41 need chemists, you need every area of human
00:05:41 --> 00:05:43 scientific endeavour to come together.
00:05:43 --> 00:05:45 Because as scientists, our knowledge is
00:05:45 --> 00:05:47 somewhat siloed. I think I've said in
00:05:47 --> 00:05:49 previous episodes, the further you go away
00:05:49 --> 00:05:51 from what your speciality is, the more out of
00:05:51 --> 00:05:53 debt and the more superficial your knowledge
00:05:53 --> 00:05:55 is. So I always view my knowledge as being
00:05:55 --> 00:05:57 almost like a Christmas tree shape. I've got
00:05:57 --> 00:05:59 a lot of knowledge about a very narrow area
00:05:59 --> 00:06:01 at the top. And the further you go from that
00:06:01 --> 00:06:03 area, the less knowledge I have, but the
00:06:03 --> 00:06:05 broader my knowledge base gets. And I think
00:06:05 --> 00:06:07 every human's like that. And um, you can
00:06:07 --> 00:06:09 almost imagine that if you're trying to
00:06:09 --> 00:06:11 answer the question of what you need for
00:06:11 --> 00:06:13 life, where we should look, which, what we'll
00:06:13 --> 00:06:15 talk about a lot today. You need a level
00:06:15 --> 00:06:17 that's above a certain point on that
00:06:17 --> 00:06:18 Christmas tree of knowledge to be able to
00:06:18 --> 00:06:20 contribute to that from a scientific
00:06:20 --> 00:06:23 advancement point of view. And the area
00:06:23 --> 00:06:25 that you can cover yourself is generally
00:06:25 --> 00:06:26 fairly small. There's a lot of knowledge that
00:06:26 --> 00:06:29 is needed that is outside your silo.
00:06:29 --> 00:06:31 And so that's where the interdisciplinary
00:06:31 --> 00:06:34 nature comes in. No one discipline can answer
00:06:34 --> 00:06:36 it their own. And that means astrobiology
00:06:36 --> 00:06:39 conferences tend to be mind bogglingly
00:06:39 --> 00:06:41 bonkers. And you get people from very
00:06:41 --> 00:06:43 different disciplines along
00:06:44 --> 00:06:46 and you learn a lot that updates your
00:06:46 --> 00:06:48 knowledge from when you went to high school.
00:06:48 --> 00:06:50 You also learn a lot that isn't about the
00:06:50 --> 00:06:52 science, but is about the scientists.
00:06:53 --> 00:06:54 And it's really interesting because we all
00:06:54 --> 00:06:56 think we're individuals. It's like that Monty
00:06:56 --> 00:06:57 Python thing, isn't it? We're all individuals
00:06:57 --> 00:06:59 and there's a Voice at the back that goes,
00:06:59 --> 00:07:01 I'm not, I'm not. Yeah, it's a bit like that.
00:07:01 --> 00:07:03 Uh, we all think, we're all individuals and
00:07:03 --> 00:07:05 we're very unique in the way we think and the
00:07:05 --> 00:07:07 way we present. But when you go to one of
00:07:07 --> 00:07:08 these conferences, that's so
00:07:08 --> 00:07:10 multidisciplinary. The different
00:07:10 --> 00:07:13 disciplines present in different ways to one
00:07:13 --> 00:07:14 another. But within the discipline there are
00:07:14 --> 00:07:16 similarities, you know. So if you see the
00:07:16 --> 00:07:19 talks I give, I have beautiful pictures and
00:07:19 --> 00:07:21 bright text, white or yellow on them, limited
00:07:21 --> 00:07:23 text, usually a dark background. And that's
00:07:23 --> 00:07:26 really common for astronomers. You go to a
00:07:26 --> 00:07:29 talk by a kind of plate tectonics person
00:07:29 --> 00:07:31 and suddenly you've got this mishmash of
00:07:31 --> 00:07:34 colours on a total different background where
00:07:34 --> 00:07:36 there's a bit more text. But the colour
00:07:36 --> 00:07:39 schemes are a bit, to me, kind of psychedelic
00:07:39 --> 00:07:40 and like something you'd see out of a 1970s
00:07:40 --> 00:07:43 cartoon, you know, because they're used to
00:07:43 --> 00:07:44 working with these geological maps that, uh,
00:07:45 --> 00:07:47 um, have a very different colour palette and
00:07:47 --> 00:07:49 sensibility, I think. And then you get talks
00:07:49 --> 00:07:51 from the biologists where they've got the
00:07:51 --> 00:07:53 name of one bacterium and it fills half of
00:07:53 --> 00:07:55 the page because it's such a lengthy
00:07:55 --> 00:07:56 scientific name. And they've got loads of
00:07:56 --> 00:07:59 texts. And so you learn a lot about how
00:08:00 --> 00:08:02 what you study at university and what
00:08:02 --> 00:08:05 discipline you go into trains you to
00:08:05 --> 00:08:08 think and transit to problem solve. Because
00:08:08 --> 00:08:10 it trains you in a lot of different ways,
00:08:10 --> 00:08:12 essentially, programmes, people. And, um, you
00:08:12 --> 00:08:14 know, I find that side of things really
00:08:14 --> 00:08:16 fascinating because it's a good way to learn
00:08:16 --> 00:08:18 to improve your communication skills. And you
00:08:18 --> 00:08:20 also pick up all this abundance of,
00:08:21 --> 00:08:23 wow, I never knew that, you know. And that's
00:08:23 --> 00:08:26 what we need if we are to answer questions
00:08:26 --> 00:08:28 like, how did life begin? Where did life come
00:08:28 --> 00:08:30 from? Are we alone? Um, yeah.
00:08:30 --> 00:08:32 Andrew Dunkley: And that's really an interesting question
00:08:32 --> 00:08:35 because, uh, it could be life
00:08:35 --> 00:08:36 not as we know it.
00:08:36 --> 00:08:38 Like we, you know, we're assuming carbon
00:08:38 --> 00:08:41 based life forms, but there could be life
00:08:41 --> 00:08:43 forms that have been created out of a
00:08:43 --> 00:08:45 completely different soup mix. Two, uh,
00:08:45 --> 00:08:47 things I want to get out of the way quickly.
00:08:47 --> 00:08:50 The Drake Equation, which was, uh, created
00:08:50 --> 00:08:53 to try and assess how much intelligent
00:08:53 --> 00:08:56 life that was able to communicate existed in
00:08:56 --> 00:08:57 the universe. And the answer is still one.
00:08:58 --> 00:09:01 And the Fermi paradox, which says, you know,
00:09:01 --> 00:09:04 um, that statistically there's a
00:09:04 --> 00:09:06 high probability of extraterrestrial life.
00:09:07 --> 00:09:09 So where is everybody? And
00:09:09 --> 00:09:12 that's what astrobiology is really, isn't it?
00:09:12 --> 00:09:15 Where is everybody? And. And will they be
00:09:15 --> 00:09:17 people or will they be microbes?
00:09:17 --> 00:09:20 And I suppose my first question to you
00:09:20 --> 00:09:23 is, uh, you're talking about finding life
00:09:23 --> 00:09:25 outside the solar system. Aren't we likely
00:09:25 --> 00:09:28 to find it first within the solar system?
00:09:29 --> 00:09:31 Jonti Horner: So that's a really good question. I was going
00:09:31 --> 00:09:32 to talk about that a bit as well, because I
00:09:32 --> 00:09:35 think there are two different places.
00:09:35 --> 00:09:37 In a broad sense, we're looking for life
00:09:37 --> 00:09:40 elsewhere. One is in the
00:09:40 --> 00:09:42 outer solar system or on Mars, you know, in
00:09:42 --> 00:09:44 our solar system, on one of the planets or,
00:09:44 --> 00:09:46 uh, on the icy objects. And the other is
00:09:46 --> 00:09:48 beyond the solar system. And those two
00:09:48 --> 00:09:51 things have very different
00:09:51 --> 00:09:54 characteristics. What I mean
00:09:54 --> 00:09:56 by that is that, uh, objects that are in our
00:09:56 --> 00:09:59 solar system are in our backyard. They're the
00:09:59 --> 00:10:01 only things in astronomy that we can get up
00:10:01 --> 00:10:03 close and personal with. So in the solar
00:10:03 --> 00:10:06 system, the search for life elsewhere is
00:10:06 --> 00:10:09 being driven by robotic exploration. In the
00:10:09 --> 00:10:10 Moon. Yes, there's a little bit of
00:10:11 --> 00:10:14 observation from Earth. We saw that with the
00:10:14 --> 00:10:16 phosphine storey on Venus that I ranted about
00:10:16 --> 00:10:18 a little bit last week. Um, and, um, the
00:10:18 --> 00:10:20 wonderful caution shown by scientists that
00:10:20 --> 00:10:21 was not necessarily reflected in the
00:10:21 --> 00:10:24 coverage. Um, but a lot of the research
00:10:25 --> 00:10:28 in the solar system is robotic in nature. We
00:10:28 --> 00:10:30 send spacecraft to places to study them up
00:10:30 --> 00:10:33 close and personal. And we can't do that
00:10:33 --> 00:10:35 around other stars. Around other stars. It's
00:10:35 --> 00:10:37 very much a remote sensing type deal. So
00:10:37 --> 00:10:40 there are different ways of doing it. Now, I
00:10:40 --> 00:10:41 think there is a realistic chance we'll find
00:10:41 --> 00:10:44 life elsewhere in the solar system. There's a
00:10:44 --> 00:10:46 lot of good reasons for that. Now, before I
00:10:46 --> 00:10:48 dive into that a little bit, I'll just take a
00:10:48 --> 00:10:50 step back and come back to that point you
00:10:50 --> 00:10:51 made about life like us and carbon based life
00:10:51 --> 00:10:53 versus other things. Because it's really
00:10:53 --> 00:10:56 important to make explicit what is normally
00:10:56 --> 00:10:58 an implicit bias when
00:10:58 --> 00:11:01 scientists are talking about astrobiology.
00:11:01 --> 00:11:03 It's really made clear when you think about
00:11:03 --> 00:11:06 NASA and Issa's efforts on the moon, where
00:11:06 --> 00:11:08 they have. On, um, Mars, sorry, where they
00:11:08 --> 00:11:10 have aggressively said the strategy to look
00:11:10 --> 00:11:12 for life is to follow the water.
00:11:13 --> 00:11:15 What they're doing there is making
00:11:16 --> 00:11:18 an implicit assumption. That is an assumption
00:11:18 --> 00:11:20 that is not always written out and is clear,
00:11:20 --> 00:11:23 but is at the back of it, that life
00:11:23 --> 00:11:25 that we look for will be life like us. And I
00:11:25 --> 00:11:28 mean life like Earth life. Now we can
00:11:28 --> 00:11:30 imagine. You see it on science fiction all
00:11:30 --> 00:11:32 the time. You know, life that is very other.
00:11:32 --> 00:11:34 It might be molten metal monsters on a magma
00:11:34 --> 00:11:36 planet, or it might be an intelligent
00:11:36 --> 00:11:37 hydrogen cloud that nevertheless wants to
00:11:37 --> 00:11:40 flirt with Captain Kirk. It's
00:11:40 --> 00:11:42 very different kinds of life, but
00:11:42 --> 00:11:45 Fundamentally we only know of one type of
00:11:45 --> 00:11:47 life that does exist, and that's life
00:11:47 --> 00:11:50 like Earth life. And so when we
00:11:50 --> 00:11:53 look for life elsewhere, at ah, least in
00:11:53 --> 00:11:56 what is the early stages still, it is really
00:11:56 --> 00:11:58 important to look for something that we know
00:11:58 --> 00:12:01 can exist and does exist, rather than
00:12:01 --> 00:12:02 looking for things that we could speculate
00:12:02 --> 00:12:05 might exist. If you've got to focus your
00:12:05 --> 00:12:08 efforts with limited resources, it
00:12:08 --> 00:12:10 makes sense to follow the kind of well
00:12:10 --> 00:12:12 trodden footsteps of what we know about life
00:12:12 --> 00:12:14 on Earth. And um, from an astronomer's point
00:12:14 --> 00:12:16 of view, life on Earth needs three things.
00:12:16 --> 00:12:19 You know, it needs liquid water, it needs a
00:12:19 --> 00:12:20 source of energy and a source of nutrients.
00:12:20 --> 00:12:22 And quite often those two are the same thing,
00:12:22 --> 00:12:25 but not always. And wherever we find those
00:12:25 --> 00:12:27 things on Earth, we find life in abundance.
00:12:27 --> 00:12:29 And once life gets there, it's really hard to
00:12:29 --> 00:12:31 get rid of. You know, anybody who's had ants
00:12:31 --> 00:12:33 getting into their kitchen or the mice plague
00:12:33 --> 00:12:36 that we talked about last week knows just how
00:12:37 --> 00:12:40 life, once it gets established, keeps going.
00:12:40 --> 00:12:43 And so it makes sense. And a lot of what I'll
00:12:43 --> 00:12:45 talk about for all the rest of the episode is
00:12:45 --> 00:12:47 kind of based on this assumption that we're
00:12:47 --> 00:12:50 looking, at least initially for life like
00:12:50 --> 00:12:52 us, has the same needs as us. Where the US is
00:12:52 --> 00:12:55 abroad, the entire panel play of life on
00:12:55 --> 00:12:58 Earth rather than us as in me and the having
00:12:58 --> 00:13:00 this chat back and forward. What
00:13:00 --> 00:13:02 that leads to though is a lot of studies that
00:13:02 --> 00:13:04 have been done for the solar system are very
00:13:04 --> 00:13:07 water driven. And if you go back decades, you
00:13:07 --> 00:13:10 could go back to the late 1800s when people
00:13:10 --> 00:13:12 were obsessed with this idea that there was
00:13:12 --> 00:13:14 an advanced technological civilization on
00:13:14 --> 00:13:16 Mars that was running out of time because the
00:13:16 --> 00:13:19 planet was desolate and barren. And this was
00:13:19 --> 00:13:21 all motivated by the observations of the
00:13:21 --> 00:13:23 canali, the channels on Mars that don't
00:13:23 --> 00:13:26 exist, which were mistranslated as canals and
00:13:26 --> 00:13:28 canals on Earth are a very clear sign of
00:13:28 --> 00:13:31 human activity. Yeah, People at
00:13:31 --> 00:13:33 that time were so certain that we'd already
00:13:33 --> 00:13:35 found life that when there was a prize
00:13:35 --> 00:13:38 awarded, um, a prize laid
00:13:38 --> 00:13:39 out, sorry, in announced, I think it was like
00:13:39 --> 00:13:42 in 1899 or something, for the search for
00:13:42 --> 00:13:44 life, for the first person to discover life
00:13:44 --> 00:13:46 elsewhere, to find evidence of life
00:13:46 --> 00:13:48 elsewhere. That prize explicitly
00:13:48 --> 00:13:51 excluded Mars because it was felt that life
00:13:51 --> 00:13:53 on Mars was so well established that that was
00:13:53 --> 00:13:55 a no brainer. You know, it was such a thing
00:13:55 --> 00:13:56 in popular culture that when the War of the
00:13:56 --> 00:13:58 Worlds broadcast happened in the 1930s,
00:13:59 --> 00:14:01 people thought it was live news coverage and
00:14:01 --> 00:14:01 panicked.
00:14:01 --> 00:14:04 Andrew Dunkley: Yes. You know, the night that panicked
00:14:04 --> 00:14:04 America.
00:14:04 --> 00:14:07 Jonti Horner: Yeah. And there's this whole heritage of
00:14:08 --> 00:14:10 our expectation of life being common
00:14:11 --> 00:14:13 and it being lifelike, us requiring water.
00:14:14 --> 00:14:17 When we went to Mars, like in the 1960s with
00:14:17 --> 00:14:19 spacecraft, Mars was shown to be the
00:14:19 --> 00:14:21 desolate, arid world we knew today. And that
00:14:21 --> 00:14:23 put to an end the thoughts of an advanced
00:14:23 --> 00:14:26 civilization there. And, um, from that time
00:14:26 --> 00:14:28 onwards there was a period where arguments in
00:14:28 --> 00:14:30 astrobiology fell very much out of favour,
00:14:30 --> 00:14:32 out of fashion. And it was kind of viewed
00:14:32 --> 00:14:34 much more likely that life was almost unique,
00:14:34 --> 00:14:36 we were alone, um, there was no way you could
00:14:36 --> 00:14:36 look.
00:14:36 --> 00:14:39 And there's this argument that I often hear
00:14:39 --> 00:14:42 espouse that water is scarce in the universe.
00:14:43 --> 00:14:45 And that makes my head hurt. I think this is
00:14:45 --> 00:14:47 one of those big myths that is a myth of
00:14:47 --> 00:14:50 miscommunication or a myth of
00:14:51 --> 00:14:53 language being a personal
00:14:54 --> 00:14:56 thing. What I mean by that is, and I'm
00:14:56 --> 00:14:58 always trying to be very aware of this when
00:14:58 --> 00:15:01 I'm, uh, as a communicator, the
00:15:01 --> 00:15:03 words have different meanings to different
00:15:03 --> 00:15:06 people. And so the same word that I
00:15:06 --> 00:15:08 say you'll hear and it doesn't always mean
00:15:08 --> 00:15:10 the same thing to you or me. And one of the
00:15:10 --> 00:15:12 best things, best examples of this is when
00:15:12 --> 00:15:14 you get people who are trying to argue
00:15:14 --> 00:15:17 against an area of science, maybe vaccines,
00:15:17 --> 00:15:19 maybe climate change, maybe something less
00:15:19 --> 00:15:21 controversial. You'll often hear people say
00:15:21 --> 00:15:23 that, well, climate change is just a theory,
00:15:23 --> 00:15:25 or, uh, vaccines are just a theory, or the
00:15:25 --> 00:15:28 Big Bang is just a theory. And to a lot of
00:15:28 --> 00:15:31 people a theory just means a loose
00:15:31 --> 00:15:34 idea. A lot of people will say,
00:15:34 --> 00:15:36 why isn't your car starting this morning?
00:15:36 --> 00:15:39 Well, I've got a theory. To a scientist, a
00:15:39 --> 00:15:41 theory is a very different beast and it's
00:15:41 --> 00:15:43 tied to the ability to make testable
00:15:43 --> 00:15:45 predictions and, um, repeated testing.
00:15:46 --> 00:15:48 There's a lot of philosophy of science. I did
00:15:48 --> 00:15:50 a philosophy of physics course at, uh,
00:15:50 --> 00:15:52 university when I was 18 and I wish I'd done
00:15:52 --> 00:15:53 it when I was at the end of my degree. Not
00:15:53 --> 00:15:54 the start, because I'd have got a lot more
00:15:54 --> 00:15:56 out of it. But there are people who've
00:15:56 --> 00:15:59 aggressively studied the philosophy of the
00:15:59 --> 00:16:02 scientific method and even that philosophy
00:16:02 --> 00:16:03 varies a little bit, discipline to
00:16:03 --> 00:16:05 discipline. A lot of other disciplines that
00:16:05 --> 00:16:07 are the experimental ones are a very much
00:16:07 --> 00:16:10 more hypothesis driven than astronomy,
00:16:10 --> 00:16:12 where we say, I'm interested in what this is,
00:16:12 --> 00:16:13 let's have a look. There's not really a
00:16:13 --> 00:16:15 hypothesis. I just want to look at it and
00:16:15 --> 00:16:17 find out. At least that's how I work. But you
00:16:17 --> 00:16:20 also have this thing where, at least from my
00:16:20 --> 00:16:22 philosophy, you can never prove a Theory, but
00:16:22 --> 00:16:24 you can disprove a theory. What I mean by
00:16:24 --> 00:16:27 that is if you test a theory a million times
00:16:28 --> 00:16:30 and each time it's backs it up, you haven't
00:16:30 --> 00:16:32 proven that theory. You've just shown that
00:16:32 --> 00:16:34 theory is a very good approximation to what's
00:16:34 --> 00:16:36 actually happening. So take the example of me
00:16:36 --> 00:16:39 flipping a coin, I can have a theory theory
00:16:39 --> 00:16:41 that says coins will always land heads or
00:16:41 --> 00:16:44 tails. Test that a million times and odds are
00:16:44 --> 00:16:46 a million times you'll land heads or tails.
00:16:46 --> 00:16:48 But you've not proven that theory. You've
00:16:48 --> 00:16:50 just said it's a very close approximation to
00:16:50 --> 00:16:52 the truth. You could toss them 10 million
00:16:52 --> 00:16:53 times and one time your coin lands on its
00:16:53 --> 00:16:55 edge and balances. Yeah, that one
00:16:55 --> 00:16:57 observation. So as long as it's well
00:16:57 --> 00:16:58 documented and is repeatable is enough to
00:16:58 --> 00:17:00 kill that theory. And then you need to
00:17:00 --> 00:17:03 develop something more complex. You know,
00:17:03 --> 00:17:04 that's where it goes from.
00:17:04 --> 00:17:07 Now, that's a very roundabout way of coming
00:17:07 --> 00:17:10 back at this water being scarce myth.
00:17:10 --> 00:17:13 I think where that comes from is when you
00:17:13 --> 00:17:16 talk to me about water, I am,
00:17:16 --> 00:17:18 um, just thinking about the molecule.
00:17:18 --> 00:17:21 I'm not thinking about the physical state. So
00:17:21 --> 00:17:23 to me, water can be water ice, it can be
00:17:23 --> 00:17:26 liquid water, it can be water vapour. But to
00:17:26 --> 00:17:28 most people, if you say water, they visualise
00:17:28 --> 00:17:31 liquid water. Yeah, if, if I say, would you
00:17:31 --> 00:17:33 like some water? You're not expecting me to
00:17:33 --> 00:17:35 immediately start steaming your face. You're
00:17:35 --> 00:17:36 expecting a glass of water. Right.
00:17:38 --> 00:17:40 What that means is that when people look out
00:17:40 --> 00:17:42 of the solar system and look everywhere else,
00:17:42 --> 00:17:44 we see this thing that Earth is the only
00:17:44 --> 00:17:46 place where we have abundant liquid water all
00:17:46 --> 00:17:49 the time on the surface. And so people
00:17:49 --> 00:17:51 have this idea that water is scarce, where
00:17:51 --> 00:17:54 what they're really thinking is liquid water
00:17:54 --> 00:17:57 on the surface of an object is scarce.
00:17:58 --> 00:18:00 But that drove a lot of this idea that life
00:18:00 --> 00:18:02 will be scarce because life needs liquid
00:18:02 --> 00:18:04 water. On Earth, the earthy and lipidates
00:18:04 --> 00:18:06 with liquid water, ergo, uh, life will be
00:18:07 --> 00:18:09 scarce. That's moved on though, in about the
00:18:09 --> 00:18:11 last three or four decades, partially with
00:18:11 --> 00:18:13 the exploration of Mars, where we're getting
00:18:14 --> 00:18:16 an overwhelmingly greater amount m of
00:18:16 --> 00:18:18 evidence that Mars in the past was warm and
00:18:18 --> 00:18:20 wet, that it had oceans and lakes. They may
00:18:20 --> 00:18:21 have been slushy or they may have been
00:18:21 --> 00:18:24 properly liquid, but it had oceans and lakes
00:18:24 --> 00:18:26 for a long time of liquid water. And we've
00:18:26 --> 00:18:27 even got evidence that there is permanent
00:18:27 --> 00:18:29 liquid water on Mars as we're talking now in
00:18:29 --> 00:18:31 the form of liquid water in the Martian Mars
00:18:31 --> 00:18:33 polar ice caps. And you get temporary liquid
00:18:33 --> 00:18:36 Water running on the surface. The other thing
00:18:36 --> 00:18:38 we found in the solar system is liquid water
00:18:38 --> 00:18:41 in astonishing abundance in the outer solar
00:18:41 --> 00:18:44 system, protected by shells of ice on the
00:18:44 --> 00:18:47 icy satellites of the giant planets. On the
00:18:47 --> 00:18:48 dwarf planet Pluto, or inside the dwarf
00:18:48 --> 00:18:51 planet Pluto, probably in the larger, uh,
00:18:51 --> 00:18:53 Edgeworth Kuiper Belt objects, Trans
00:18:53 --> 00:18:55 Neptunian objects, maybe in other places as
00:18:55 --> 00:18:58 well, even in places as small as Enceladus.
00:18:58 --> 00:19:01 So there's been this revolution from the
00:19:01 --> 00:19:02 point of view of the solar system through my
00:19:02 --> 00:19:05 lifetime that actually liquid water isn't
00:19:05 --> 00:19:08 scarce. Coupled to the fact that the Earth is
00:19:08 --> 00:19:10 actually remarkably dry as a planet, that
00:19:10 --> 00:19:11 suddenly opened up people's perspectives
00:19:11 --> 00:19:13 again that the solar system is a good place
00:19:13 --> 00:19:16 to look for life. And that's driving a lot of
00:19:16 --> 00:19:17 exploration, a lot of missions. All the Mars
00:19:17 --> 00:19:20 exploration past and, um, future focused
00:19:20 --> 00:19:22 around that idea. The fact that we've got two
00:19:22 --> 00:19:24 missions going to the Jovian IC satellites at
00:19:24 --> 00:19:26 the minute Juice and, um, the Jupiterizing
00:19:26 --> 00:19:29 Moons Explorer and the Europa Clipper, which
00:19:29 --> 00:19:31 are to characterise those moons better to
00:19:31 --> 00:19:33 prepare for potential future landings in the
00:19:33 --> 00:19:35 2000-40s or-50s to get through the ice and
00:19:35 --> 00:19:37 look at what's underneath. We've got the
00:19:37 --> 00:19:39 Dragonfly mission going out to Titan,
00:19:40 --> 00:19:41 launching in a couple of years time, probably
00:19:41 --> 00:19:44 next year, ah, hoping to get there 2034.
00:19:44 --> 00:19:46 That will land on the only other place that
00:19:46 --> 00:19:49 has liquid on its surface exposed to the
00:19:49 --> 00:19:50 atmosphere in the solar system, and that's
00:19:50 --> 00:19:52 Titan. With lakes of liquid methane and
00:19:52 --> 00:19:54 ethane. The water there is harder than
00:19:54 --> 00:19:57 granite and makes up the mountain. But
00:19:57 --> 00:19:58 there's this huge effort to explore our solar
00:19:58 --> 00:20:00 system and actually go there and look, which
00:20:00 --> 00:20:02 we can't do when we're looking at planets
00:20:02 --> 00:20:05 around other stars. And by going there and
00:20:05 --> 00:20:08 looking if there is anything there, past or
00:20:08 --> 00:20:11 present, eventually we'll find it. Now, that
00:20:11 --> 00:20:13 immediately then poses a really fascinating
00:20:13 --> 00:20:16 one. So if we find life on Mars or find life
00:20:16 --> 00:20:18 on Europa, if we can
00:20:19 --> 00:20:21 look at that life and figure out
00:20:22 --> 00:20:25 its heritage, figure out its DNA, and I'm not
00:20:25 --> 00:20:27 a biologist, so I'll be a little woolly on
00:20:27 --> 00:20:29 that. It will be very quick and very
00:20:29 --> 00:20:31 apparent whether that life has a shared
00:20:31 --> 00:20:33 origin to life on Earth or whether it has a
00:20:33 --> 00:20:35 separate origin to life on Earth. Now, the
00:20:35 --> 00:20:37 separate origin would mean that life got
00:20:37 --> 00:20:40 started simultaneously on two
00:20:40 --> 00:20:43 objects in the same planetary system in
00:20:43 --> 00:20:46 an icy backwater of a fairly unremarkable
00:20:46 --> 00:20:48 galaxy. If it got started two places side
00:20:48 --> 00:20:51 by side, surely that means life gets started
00:20:51 --> 00:20:53 more easily than we expect. Therefore, life
00:20:53 --> 00:20:56 should be common in the universe. That would
00:20:56 --> 00:20:59 be an obvious logical continuation. The other
00:20:59 --> 00:21:00 option is that we find life elsewhere in the
00:21:00 --> 00:21:02 solar system and it has a shared heritage to
00:21:02 --> 00:21:04 life on Earth. What that means is that, uh,
00:21:04 --> 00:21:06 we analyse its makeup, we find that it has
00:21:06 --> 00:21:09 DNA like Earth, DNA that has a shared
00:21:09 --> 00:21:12 universal common ancestor. And what that
00:21:12 --> 00:21:13 suggests is that once life gets started
00:21:13 --> 00:21:16 somewhere, it's transmissible. You know,
00:21:16 --> 00:21:17 you've got that old thing of don't go near
00:21:17 --> 00:21:19 Earth, it's got humans, they're contagious.
00:21:20 --> 00:21:22 This is the same kind of idea. If we find
00:21:22 --> 00:21:24 life on Mars and that life has a shared
00:21:24 --> 00:21:26 heritage with life on Earth, that
00:21:27 --> 00:21:29 validates strongly support c idea of
00:21:29 --> 00:21:32 panspermia, which I've had a student just
00:21:32 --> 00:21:35 submit his PhD thesis studying the
00:21:35 --> 00:21:36 idea that life can transfer between the
00:21:36 --> 00:21:39 planets. Now, again, if life can transfer
00:21:39 --> 00:21:40 easily enough to be found in multiple
00:21:40 --> 00:21:42 locations in the solar system from a simple
00:21:43 --> 00:21:45 single origin and, uh, maybe even Earth, uh,
00:21:45 --> 00:21:47 wasn't that origin. You know, maybe we're
00:21:47 --> 00:21:50 Martians, maybe we're Venusians or Venerians.
00:21:50 --> 00:21:52 I think that Venerian used to be the
00:21:52 --> 00:21:53 adjective for Venus. Adjective, the right
00:21:53 --> 00:21:55 word, used to be the word for Venus in the
00:21:55 --> 00:21:57 way that Martian was for Mars, but it was a
00:21:57 --> 00:21:59 bit too close to venereal, um, because.
00:22:01 --> 00:22:03 So they changed it. But anyway, um, but we
00:22:03 --> 00:22:05 could be venereal creatures. Um, we don't
00:22:05 --> 00:22:07 know. But what that suggests is that if life
00:22:07 --> 00:22:10 is transferred easily and effectively once it
00:22:10 --> 00:22:12 originates, life could be coming in the
00:22:12 --> 00:22:15 universe. So to me, finding life in the solar
00:22:15 --> 00:22:16 system would be awesome. I think it's
00:22:16 --> 00:22:19 eminently feasible. And either way, it will
00:22:19 --> 00:22:21 shed new light on the commonality of life
00:22:21 --> 00:22:24 beyond the solar system. We will be looking
00:22:24 --> 00:22:27 for life like us. It is possible to imagine
00:22:27 --> 00:22:28 life that is not like us, that has different
00:22:28 --> 00:22:30 requirements, but that will probably be a bit
00:22:30 --> 00:22:33 harder to find and we don't know
00:22:33 --> 00:22:36 what it would be. Whereas with life like us,
00:22:36 --> 00:22:38 we know things to look for. So that makes it
00:22:38 --> 00:22:40 a bit easier for us to look for life like us.
00:22:40 --> 00:22:43 It also makes it, I'd say,
00:22:43 --> 00:22:45 a little bit stronger as a case when you're
00:22:45 --> 00:22:47 asking for funding because you can say, well,
00:22:47 --> 00:22:49 we already know this kind of life can exist,
00:22:50 --> 00:22:51 so we're going to look at a place where the
00:22:51 --> 00:22:53 conditions are similar to where we know it
00:22:53 --> 00:22:54 does exist and, um, see if we find it there
00:22:54 --> 00:22:55 as well.
00:22:55 --> 00:22:58 Andrew Dunkley: Okay, let's take a short break. Uh, this
00:22:58 --> 00:23:01 is Space Nuts with Andrew Dunkley and
00:23:01 --> 00:23:02 Professor Jonty Horner.
00:23:05 --> 00:23:06 Yeah, I'm going to step off the
00:23:06 --> 00:23:06 Jonti Horner: lamb now
00:23:09 --> 00:23:11 that's one small step for man,
00:23:14 --> 00:23:16 one giant leap for man.
00:23:17 --> 00:23:18 Space nuts.
00:23:19 --> 00:23:21 Andrew Dunkley: It's not Professor Fred Watson Watson at the
00:23:21 --> 00:23:22 moment. He's away. We've got Professor John
00:23:22 --> 00:23:25 T. Horner, and we're talking astrobiology in
00:23:25 --> 00:23:27 this little, uh, special edition.
00:23:28 --> 00:23:30 Um, one thing I heard in the news recently,
00:23:30 --> 00:23:32 and I think Fred Watson and I talked about it
00:23:32 --> 00:23:34 was, uh, you know, we've been talking about
00:23:34 --> 00:23:36 water. And if you want to find the people,
00:23:36 --> 00:23:38 find the water, that sort of thing. But there
00:23:38 --> 00:23:41 was one particular study that was, uh,
00:23:41 --> 00:23:43 recently released that says if you want to
00:23:43 --> 00:23:45 find the people, find the coal. What do you
00:23:45 --> 00:23:46 think of that theory?
00:23:47 --> 00:23:49 Jonti Horner: That's an interesting one. So that's the idea
00:23:49 --> 00:23:51 that, uh, if you want to find somebody to
00:23:51 --> 00:23:53 talk to, there needs to be something to fuel
00:23:53 --> 00:23:56 an industrial revolution. And again, this is,
00:23:56 --> 00:23:58 I think, science fiction sometimes. Does this
00:23:58 --> 00:24:00 really ask these really interesting questions
00:24:00 --> 00:24:03 of almost is the path that we
00:24:03 --> 00:24:06 have followed the one that everyone
00:24:06 --> 00:24:08 will follow? You know, because there's so
00:24:08 --> 00:24:10 much to some degree randomness in
00:24:11 --> 00:24:13 the things that have driven our knowledge
00:24:13 --> 00:24:16 and our development of things. You know, um,
00:24:16 --> 00:24:18 obviously a good example is a famous myth
00:24:18 --> 00:24:21 about penicillin that if, um, you leave your
00:24:21 --> 00:24:22 bread out and it goes mouldy, that makes your
00:24:22 --> 00:24:25 poultice more effective. Um, and that was an
00:24:25 --> 00:24:28 incredible scientific revolution driven
00:24:28 --> 00:24:30 by that discovery. There was.
00:24:31 --> 00:24:33 Who's to say other civilizations would have
00:24:33 --> 00:24:36 the same discoveries in the same order. Now,
00:24:36 --> 00:24:39 to advance, we have required advances in
00:24:39 --> 00:24:42 energy in order to allow us to better
00:24:42 --> 00:24:44 develop technology and develop the things
00:24:44 --> 00:24:46 that everything's made of. You know, if we
00:24:46 --> 00:24:49 didn't have anything that you could burn,
00:24:49 --> 00:24:51 it would be very, very challenging to smelt
00:24:51 --> 00:24:53 metal. If you couldn't smelt metal, how do
00:24:53 --> 00:24:55 you build electronics?
00:24:55 --> 00:24:57 Andrew Dunkley: You are spot on. That's exactly what the
00:24:57 --> 00:25:00 article was all about. And, uh, the
00:25:00 --> 00:25:02 bottom line was, uh, that because of the
00:25:02 --> 00:25:05 timing required, it lessens
00:25:06 --> 00:25:09 the likelihood of us finding, uh, people
00:25:09 --> 00:25:11 like us. It reduces the odds.
00:25:11 --> 00:25:14 Jonti Horner: And this is where there's a difference
00:25:14 --> 00:25:16 between the search for extraterrestrial
00:25:16 --> 00:25:18 intelligence and the search for life. So the
00:25:18 --> 00:25:20 search for extraterrestrial intelligence is
00:25:20 --> 00:25:22 like a subset of the search for life? Yeah,
00:25:22 --> 00:25:25 search for life is a search for bacteria as
00:25:25 --> 00:25:27 much as the search for, uh, communicative
00:25:27 --> 00:25:30 aliens. And there's been a lot of stuff
00:25:30 --> 00:25:32 written and discussed about whether
00:25:33 --> 00:25:35 evolutionary quirks have benefited us by
00:25:35 --> 00:25:37 being here. You know, in terms of we're a
00:25:37 --> 00:25:39 social communal animal that shares resources
00:25:39 --> 00:25:42 and shares learning. There have been other
00:25:42 --> 00:25:43 ones like that from Ant Colins. And I'm
00:25:43 --> 00:25:46 listening to a very Chill and very
00:25:46 --> 00:25:48 silly, um, lit
00:25:48 --> 00:25:50 rpg, I think would be the description of the
00:25:50 --> 00:25:53 genre series of books called Chrysalis at the
00:25:53 --> 00:25:55 minute, where a young boy who dies for
00:25:56 --> 00:25:58 reasons is reincarnated in the bottom born
00:25:58 --> 00:26:01 body of an ant. And it's a book about him
00:26:01 --> 00:26:03 as an ant and his life in the colony and
00:26:03 --> 00:26:06 stuff, and it's bonkers. But, um,
00:26:06 --> 00:26:08 you've got an advanced social species there
00:26:08 --> 00:26:11 and he finds ways, without too many spoilers,
00:26:11 --> 00:26:12 of giving them intelligence and what happens
00:26:12 --> 00:26:14 afterwards. There's a few species in the
00:26:14 --> 00:26:16 history of Earth that have that kind of
00:26:16 --> 00:26:19 communal sharing of information thing. We're
00:26:19 --> 00:26:20 the only ones that have achieved what we've
00:26:20 --> 00:26:23 achieved. Some arguments are that's down to
00:26:23 --> 00:26:26 the development of language and our ability
00:26:26 --> 00:26:28 to produce complex language, and also the
00:26:28 --> 00:26:30 opposable thumb being quite important. So
00:26:30 --> 00:26:33 there's a lot of stuff that there are many
00:26:33 --> 00:26:35 steps between the development of life and the
00:26:35 --> 00:26:38 development of intelligence. And, uh, the
00:26:38 --> 00:26:39 development of intelligence itself doesn't
00:26:39 --> 00:26:41 necessarily mean the development of
00:26:41 --> 00:26:43 technological intelligence. You know, a lot
00:26:43 --> 00:26:45 of discussions about all the things octopi or
00:26:45 --> 00:26:48 octopods or octopiddles, octopi could
00:26:48 --> 00:26:50 achieve if they lived for more than three
00:26:50 --> 00:26:52 years. And if they were a social animal,
00:26:52 --> 00:26:54 they've got incredible brands. We're learning
00:26:54 --> 00:26:56 more and more about some of the brain power
00:26:56 --> 00:26:59 that birds exhibit, but
00:26:59 --> 00:27:01 none of them have become technological
00:27:01 --> 00:27:02 intelligences. And the search for
00:27:02 --> 00:27:05 extraterrestrial intelligence is very much
00:27:05 --> 00:27:07 centred around a technology
00:27:08 --> 00:27:10 that allows civilizations to communicate with
00:27:10 --> 00:27:13 one another. That therefore is based on many
00:27:13 --> 00:27:15 prerequisites that lead to the development of
00:27:15 --> 00:27:17 the ability to broadcast your existence to
00:27:17 --> 00:27:18 the cosmos.
00:27:18 --> 00:27:20 The coal thing's interesting. I mean, I'm not
00:27:21 --> 00:27:23 sufficiently archaeologically
00:27:23 --> 00:27:26 minded to be able to
00:27:26 --> 00:27:29 say with certainty that without coal we
00:27:29 --> 00:27:30 wouldn't have got here. And, uh, the reason
00:27:30 --> 00:27:32 that I express caution on that coal and oil
00:27:33 --> 00:27:35 is that we have things that people burn for
00:27:35 --> 00:27:37 energy that are not coal and oil.
00:27:38 --> 00:27:40 And I think a lot of the smelting that was
00:27:40 --> 00:27:41 done, and I may be wrong on this because I'm
00:27:41 --> 00:27:43 not an archaeologist, I just picked bits up
00:27:43 --> 00:27:45 when my partner's watching Time Tim and
00:27:45 --> 00:27:46 things like that. She loves her archaeology,
00:27:46 --> 00:27:49 so I get a little bit of that as a very thin
00:27:49 --> 00:27:51 veneer. But I think a lot of this times when
00:27:51 --> 00:27:53 people smelted metals, talking about bronze
00:27:53 --> 00:27:55 and iron, they used wood or they used
00:27:55 --> 00:27:57 charcoal, which is a byproduct of burning
00:27:57 --> 00:27:58 wood.
00:27:58 --> 00:27:59 Andrew Dunkley: Yeah.
00:27:59 --> 00:28:02 Jonti Horner: So maybe it would be more challenging without
00:28:02 --> 00:28:05 the easy available energy of fossil
00:28:05 --> 00:28:07 fuels, without the easy available energy of
00:28:07 --> 00:28:10 coal, oil, gas, but it might be that
00:28:10 --> 00:28:12 that wouldn't be an insurmountable hurdle,
00:28:12 --> 00:28:13 but it would result in a different path being
00:28:13 --> 00:28:16 followed. You know, what would we get
00:28:16 --> 00:28:18 in terms of seam power if we were using wood
00:28:18 --> 00:28:21 and if we were using charcoal rather than
00:28:21 --> 00:28:23 other things? Would it lead to an earlier
00:28:23 --> 00:28:26 adoption of renewable energy in the form of
00:28:26 --> 00:28:28 wind power, which was actually being used for
00:28:28 --> 00:28:30 hundreds of years? You go back to Europe and
00:28:30 --> 00:28:32 you see the windmills people use and water
00:28:32 --> 00:28:35 mills peoples use. So I.
00:28:35 --> 00:28:37 I don't know whether.
00:28:38 --> 00:28:40 And this is a problem with all of
00:28:40 --> 00:28:42 astrobiology and it's a problem with a lot of
00:28:42 --> 00:28:43 the stuff that I'll talk about later, about
00:28:43 --> 00:28:45 what makes a planet more suitable or less
00:28:45 --> 00:28:48 suitable. People have this tendency to
00:28:48 --> 00:28:50 find something that is unusual about us.
00:28:51 --> 00:28:52 And there's a lot that's unusual about us. I
00:28:52 --> 00:28:54 mean, there's a lot that's unusual about me.
00:28:54 --> 00:28:56 And I hold my hand up about that. But they
00:28:56 --> 00:28:59 find things that are unusual. And, um,
00:28:59 --> 00:29:01 they say we are, as far as we know, unique in
00:29:01 --> 00:29:03 the cosmos. We are a technologically advanced
00:29:03 --> 00:29:05 civilization able to have this discussion.
00:29:06 --> 00:29:08 There has to be a reason that we're here.
00:29:09 --> 00:29:12 Everything that is unusual quite often gets
00:29:12 --> 00:29:14 held up as could this be the switch? If you
00:29:14 --> 00:29:17 didn't have this, we would not be here. And I
00:29:17 --> 00:29:19 tend to view them not as an on off switch,
00:29:19 --> 00:29:22 but as a slider. They're like. And again, a
00:29:22 --> 00:29:23 gaming analogy would be varying the
00:29:23 --> 00:29:26 difficulty on your game. Some games, it's
00:29:26 --> 00:29:28 very kind of on off, hard mode, easy mode.
00:29:28 --> 00:29:30 Others, particularly some of the role playing
00:29:30 --> 00:29:33 type games people play, have sliders for
00:29:33 --> 00:29:36 everything. And so you can change things to
00:29:36 --> 00:29:39 the nth degree to tweak the challenge
00:29:39 --> 00:29:41 level. And I think all of these things, like
00:29:41 --> 00:29:44 the existence of call that get proposed
00:29:44 --> 00:29:47 as being a boundary, as being
00:29:47 --> 00:29:48 something that would be a block if you didn't
00:29:48 --> 00:29:51 have it, are actually probably more like one
00:29:51 --> 00:29:52 of those sliders. They're things that can
00:29:52 --> 00:29:55 facilitate. But it's really interesting
00:29:55 --> 00:29:57 to discuss them because we don't know how big
00:29:57 --> 00:29:59 a filter they are. We don't know how big a
00:29:59 --> 00:30:02 hurdle they are without digging into it more.
00:30:02 --> 00:30:04 And the more we can suggest these things, the
00:30:04 --> 00:30:06 more we can narrow them down. But ultimately
00:30:06 --> 00:30:08 the only way we can finally test them is when
00:30:08 --> 00:30:11 we get a response to us, when we find
00:30:11 --> 00:30:14 technologically advanced life and
00:30:14 --> 00:30:16 then we learn about their heritage. What path
00:30:16 --> 00:30:19 did they follow? Did they invent fire
00:30:19 --> 00:30:21 before the wheel? Did they invent
00:30:21 --> 00:30:24 modern medicine before fire?
00:30:24 --> 00:30:27 And I've seen there's a fabulous
00:30:28 --> 00:30:30 famous old thread I don't know. It wasn't
00:30:30 --> 00:30:32 from Reddit, predates Reddit, but from one of
00:30:32 --> 00:30:34 the old messaging boards that talks
00:30:34 --> 00:30:37 about humans as the horror
00:30:37 --> 00:30:40 movie monsters of the universe. Because we
00:30:40 --> 00:30:42 always, in science fiction, all the monsters
00:30:42 --> 00:30:44 we face, all the aliens we face, are usually
00:30:44 --> 00:30:47 more something than us. And we overcome
00:30:47 --> 00:30:49 incredible odds to beat them. But this is
00:30:49 --> 00:30:51 taking the other perspective of another
00:30:51 --> 00:30:52 species kind of looking at us and going,
00:30:52 --> 00:30:54 those humans are terrifying. And it's listing
00:30:54 --> 00:30:55 all the ways we are. You know, we're an
00:30:55 --> 00:30:58 exhaustion hunter. We didn't beat things by
00:30:58 --> 00:31:00 speed or anything. We'd follow them until
00:31:00 --> 00:31:03 they died of exhaustion because we
00:31:03 --> 00:31:05 can go longer than they can. Where are you?
00:31:05 --> 00:31:07 They were saying, you know, it's the only
00:31:07 --> 00:31:09 intelligent technological species that, uh,
00:31:09 --> 00:31:11 invented amputation before painkillers.
00:31:12 --> 00:31:14 You know, we've got things like this that are
00:31:14 --> 00:31:17 very bizarre about us. And so that takes
00:31:17 --> 00:31:19 this perspective I've got of these things are
00:31:19 --> 00:31:22 a hurdle. And you develop things, you know
00:31:22 --> 00:31:24 that things are not on an off switch, but
00:31:24 --> 00:31:26 they're more of a slider. And the idea of
00:31:27 --> 00:31:29 will things naturally be developed in the
00:31:29 --> 00:31:31 same order? And turns it around and said,
00:31:31 --> 00:31:33 what would another species think looking at
00:31:33 --> 00:31:35 us? And I always find that really good fun.
00:31:35 --> 00:31:37 And it's effectively leads to the thing that
00:31:37 --> 00:31:39 humans are space orcs and where this
00:31:39 --> 00:31:42 terrible, terrifying, weird little species.
00:31:42 --> 00:31:44 And maybe that's what it'll turn out to be.
00:31:45 --> 00:31:48 Andrew Dunkley: Well, yeah, look, uh, I don't
00:31:48 --> 00:31:51 dispute that because look how we treat each
00:31:51 --> 00:31:52 other or have treated each other,
00:31:53 --> 00:31:55 um, since civilization began,
00:31:55 --> 00:31:58 basically. I don't think you could add up
00:31:58 --> 00:32:00 how many wars we've fought against each
00:32:00 --> 00:32:03 other. I
00:32:03 --> 00:32:05 don't think that would stop. If we found
00:32:05 --> 00:32:07 another intelligent life form, I don't think
00:32:07 --> 00:32:09 we'd go in saying, hi, hey, we're really
00:32:09 --> 00:32:12 nice. I got a feeling we'd, you know,
00:32:12 --> 00:32:13 there'd be a bit of adversarial.
00:32:15 --> 00:32:17 Jonti Horner: It's a really, it is a really interesting
00:32:17 --> 00:32:17 one.
00:32:17 --> 00:32:19 It's one of the things that people factor
00:32:19 --> 00:32:22 into a lot of the discussions about the, the
00:32:22 --> 00:32:25 rights and wrongs of active seti.
00:32:25 --> 00:32:27 So active SETI is sending out a message
00:32:27 --> 00:32:29 saying, hi, we're here. Please talk to us.
00:32:29 --> 00:32:31 Whereas passive SETI is listening for people
00:32:31 --> 00:32:33 saying, please turn neighbours off. We're
00:32:33 --> 00:32:34 sick of seeing it. You know, they're
00:32:34 --> 00:32:36 effectively the two ways you can do seti.
00:32:37 --> 00:32:39 There are, uh, a lot of people in the past
00:32:39 --> 00:32:41 that have argued that active set is a bad
00:32:41 --> 00:32:42 idea because it will attract the wrong kind
00:32:42 --> 00:32:45 of attention. Well, Stephen Hawking certainly
00:32:45 --> 00:32:47 thought that, um, and throwing
00:32:47 --> 00:32:49 noshead. I think the great Mark Commode,
00:32:49 --> 00:32:52 who's a film reviewer in the uk, um, often
00:32:52 --> 00:32:54 says, you know, uh, other opinions are
00:32:54 --> 00:32:56 available. They're wrong, but they are
00:32:56 --> 00:32:58 available. I mean, this, I think, is a case
00:32:58 --> 00:33:01 of that. I think, if any, for me, and I will
00:33:01 --> 00:33:03 admit I'm an optimist, I'm also not exactly
00:33:03 --> 00:33:06 the world's most aggressive person. But for
00:33:06 --> 00:33:08 me, if you have survived as a species for
00:33:08 --> 00:33:11 long enough to be a thriving civilization to
00:33:11 --> 00:33:12 the point of wanting to communicate to the
00:33:12 --> 00:33:15 upscale upstarts that are broadcasting, you
00:33:15 --> 00:33:16 know, Big Brother and all the rest of it, to
00:33:16 --> 00:33:19 the universe, that suggests that to some
00:33:19 --> 00:33:22 degree you've overcome your martiality. Um,
00:33:22 --> 00:33:25 because I think for us to survive to the
00:33:25 --> 00:33:27 point where we're moving out into the stars
00:33:27 --> 00:33:29 will require us not to first wipe ourselves
00:33:29 --> 00:33:32 out. And the more advanced you get, the more
00:33:32 --> 00:33:35 you disperse, probably, fingers crossed,
00:33:35 --> 00:33:37 hopefully, the less likely that becomes. Now,
00:33:37 --> 00:33:39 we look at the world around us today, and
00:33:39 --> 00:33:40 without digging into politics, there's always
00:33:40 --> 00:33:43 something nasty going on. There's many, many
00:33:43 --> 00:33:45 tragedies that are both frontline in the news
00:33:45 --> 00:33:47 and forgotten by the news. But
00:33:48 --> 00:33:50 I saw a great article a few years ago
00:33:51 --> 00:33:53 that was arguing that, you know, when was the
00:33:53 --> 00:33:54 worst time to ever live, and saying that
00:33:54 --> 00:33:57 actually, despite the fact that all this war,
00:33:57 --> 00:33:59 all this aggression, all this violence is so
00:33:59 --> 00:34:02 front and centre, this is actually the safest
00:34:02 --> 00:34:03 era to live in that humanity's ever
00:34:03 --> 00:34:06 experienced. The number of people dying
00:34:06 --> 00:34:08 before their time, dying before they reach
00:34:08 --> 00:34:11 senescence, is lower per thousand people, up
00:34:11 --> 00:34:13 a hundred thousand people than ever before.
00:34:14 --> 00:34:16 You have a much lower chance as an average
00:34:16 --> 00:34:18 person of ever fighting in a war, of ever
00:34:18 --> 00:34:20 being murdered or assaulted. So
00:34:20 --> 00:34:22 we're already moving that way if it doesn't
00:34:22 --> 00:34:25 feel like it. And so to me, with that
00:34:25 --> 00:34:27 optimistic viewpoint, I would like to
00:34:27 --> 00:34:30 think that there is no reason for conflict
00:34:30 --> 00:34:32 and no reason for friction. And I think a lot
00:34:32 --> 00:34:35 of the arguments that humanity's, uh, future
00:34:35 --> 00:34:38 encounters with aliens must by necessity be
00:34:38 --> 00:34:41 violent is telling you more about people than
00:34:41 --> 00:34:42 it's telling you about aliens. Because it's
00:34:42 --> 00:34:44 saying when we look in the mirror, we see the
00:34:44 --> 00:34:47 angry, snarling, tribalist ape rather than
00:34:47 --> 00:34:49 the rational modern human that is a
00:34:49 --> 00:34:52 veneer. On m top. We're still a tribal
00:34:52 --> 00:34:55 species, we're still the product of our
00:34:55 --> 00:34:57 evolution and society is a veneer that we put
00:34:57 --> 00:35:00 on top of that as we learn, um, to be
00:35:00 --> 00:35:02 better, to be the kind of thinking social
00:35:02 --> 00:35:05 app, I guess. And the
00:35:05 --> 00:35:06 evidence is that over time we're getting
00:35:06 --> 00:35:08 better at that. Even though we're now more
00:35:08 --> 00:35:10 capable of killing each other than we ever
00:35:10 --> 00:35:13 were before. Yeah. We're doing it less often.
00:35:13 --> 00:35:14 Andrew Dunkley: Yes, we are.
00:35:14 --> 00:35:16 M. All right, we'll take a quick breather
00:35:16 --> 00:35:19 because I want to get into the, um, the
00:35:19 --> 00:35:22 area of, um, finding this
00:35:22 --> 00:35:25 life beyond our solar system. How, how are we
00:35:25 --> 00:35:26 going to. At where we're going to look and
00:35:26 --> 00:35:27 Jonti Horner: what we've got to look for.
00:35:27 --> 00:35:30 Andrew Dunkley: That's all coming up on this edition of Space
00:35:30 --> 00:35:30 Nuts.
00:35:35 --> 00:35:36 Jonti Horner: Space Nuts.
00:35:36 --> 00:35:38 Andrew Dunkley: So, Jotty, look, lead the way. Where do you
00:35:38 --> 00:35:40 want to go from here? We're gonna, uh, this
00:35:40 --> 00:35:41 is our final segment.
00:35:41 --> 00:35:44 So, um, I suppose if you're going to try and
00:35:44 --> 00:35:47 find life beyond our solar system,
00:35:48 --> 00:35:50 uh, you've got to find the right environment.
00:35:50 --> 00:35:53 Um, you know, rocky planet, habitable zone,
00:35:53 --> 00:35:54 perhaps. Um,
00:35:56 --> 00:35:58 and there's a lot more to it than that. It's
00:35:58 --> 00:36:00 not just, uh, a planet with perhaps liquid
00:36:00 --> 00:36:03 water on its surface. Uh,
00:36:04 --> 00:36:05 you've got to have, I suppose, the right kind
00:36:05 --> 00:36:08 of star. You don't want a red dwarf because
00:36:08 --> 00:36:10 you probably just, you know, get really bad
00:36:10 --> 00:36:12 sunburn. Uh, there's a lot to take
00:36:12 --> 00:36:13 into account.
00:36:14 --> 00:36:15 Jonti Horner: There's a huge amount of depth to it. And I
00:36:15 --> 00:36:18 think, as we saw with the previous episode,
00:36:18 --> 00:36:20 we could have talked another hour and we
00:36:20 --> 00:36:21 could have talked another week. To be honest,
00:36:21 --> 00:36:23 when we're talking about this stuff, one of
00:36:23 --> 00:36:25 the things I, I most adore about
00:36:25 --> 00:36:28 science is the infinite complexity. So you
00:36:28 --> 00:36:30 ask a question, when you get an answer that
00:36:30 --> 00:36:32 isn't it. But you get another 10 questions
00:36:32 --> 00:36:34 and the more you know about a subject, the
00:36:34 --> 00:36:36 more complexity there is. To me, that's just
00:36:36 --> 00:36:38 a wonder. And that's fascinating and this is
00:36:38 --> 00:36:41 a really good example of that. Now, one of my
00:36:42 --> 00:36:45 strongest arguments through my career
00:36:46 --> 00:36:49 has been that we can't just, when we're
00:36:49 --> 00:36:50 trying to think about where we're going to
00:36:50 --> 00:36:52 search for life beyond the solar system, use
00:36:52 --> 00:36:54 a habitable zone. Um, and that's it. You
00:36:54 --> 00:36:57 know, it seems like a lot of coverage and a
00:36:57 --> 00:36:59 lot of papers just go, Earth, like planet
00:36:59 --> 00:37:00 found in the habitable zone.
00:37:00 --> 00:37:01 Andrew Dunkley: Whee.
00:37:01 --> 00:37:04 Jonti Horner: And ah. And um, that's about it. Now the
00:37:04 --> 00:37:06 habitable zone has become a really effective
00:37:06 --> 00:37:08 communication tool in much same way the Drake
00:37:08 --> 00:37:11 Equation has. The Drake Equation is this
00:37:11 --> 00:37:12 fabulous tool with all the sliders where you
00:37:12 --> 00:37:15 can make your own, um, inhabited universe
00:37:15 --> 00:37:17 with lots of few aliens by varying the
00:37:17 --> 00:37:20 variables. The habitable zone has become
00:37:20 --> 00:37:22 another of these catch all kind of
00:37:22 --> 00:37:24 visualisations. And it's born of the idea
00:37:24 --> 00:37:26 that life needs liquid water with the
00:37:26 --> 00:37:29 implicit extension of that, that life needs
00:37:29 --> 00:37:31 liquid water on a planet's surface.
00:37:32 --> 00:37:34 Now, that's initially motivated by the fact
00:37:34 --> 00:37:36 that the Earth is the only place with life
00:37:36 --> 00:37:38 and back when this was being discussed, the
00:37:38 --> 00:37:41 only place with liquid water that we knew. So
00:37:41 --> 00:37:42 therefore it was natural to say you need
00:37:42 --> 00:37:45 surface liquid water. As we discussed
00:37:45 --> 00:37:46 earlier, there are plenty of places in the
00:37:46 --> 00:37:48 solar system that do not have liquid water on
00:37:48 --> 00:37:50 the surface, but do have it underneath.
00:37:50 --> 00:37:53 They've got soft centres. But the habitable
00:37:53 --> 00:37:55 zone, um, says you need liquid water
00:37:56 --> 00:37:58 on the surface of a planet for that planet to
00:37:58 --> 00:38:00 be considered suitable for life to be
00:38:00 --> 00:38:03 habitable. Now, that isn't entirely
00:38:03 --> 00:38:05 true, but for the purposes of this, it's
00:38:05 --> 00:38:08 still useful because life buried beneath
00:38:08 --> 00:38:10 ice is so hard to find that we can't find it
00:38:10 --> 00:38:12 in our own solar system. Because the ice is
00:38:12 --> 00:38:14 in the way, we wouldn't have a chance to run
00:38:14 --> 00:38:16 planets around other stars. So even though I
00:38:16 --> 00:38:18 think the habitable zone is a bigger
00:38:18 --> 00:38:20 oversimplification, I see merit to it,
00:38:20 --> 00:38:22 because life on a planet's surface with
00:38:22 --> 00:38:25 only atmosphere above is much more likely to
00:38:25 --> 00:38:27 be detectable than life buried deep in the
00:38:27 --> 00:38:29 interior. So, fair enough, we'll go with it.
00:38:29 --> 00:38:31 The idea of the habitable zone, though, is
00:38:31 --> 00:38:33 that the closer you are to a star, the hotter
00:38:33 --> 00:38:35 you are, the further away you are, the cooler
00:38:35 --> 00:38:37 you are. And just like Goldilocks and the
00:38:37 --> 00:38:39 Three Bears, which is why it's often called
00:38:39 --> 00:38:40 the Goldilocks Zone, there's a place where
00:38:40 --> 00:38:42 it's just right, it's not too hot, not too
00:38:42 --> 00:38:44 cold, and therefore there could be liquid
00:38:44 --> 00:38:47 water on the surface of the planet. Now, a
00:38:47 --> 00:38:49 lot of the time when people say a planet is
00:38:49 --> 00:38:52 in the habitable zone, um, that's
00:38:52 --> 00:38:55 often taken as meaning that planet could and
00:38:55 --> 00:38:57 potentially will have liquid water on the
00:38:57 --> 00:38:59 surface. But actually, what it's saying is,
00:38:59 --> 00:39:02 if you took the Earth as the Earth is today,
00:39:02 --> 00:39:05 and put it in that system, would it still
00:39:05 --> 00:39:06 look like the Earth? Would it have liquid
00:39:06 --> 00:39:09 water on its surface? Now, now
00:39:09 --> 00:39:11 we've extended a bit beyond that. There are a
00:39:11 --> 00:39:13 couple of fabulous papers a bit more than a
00:39:13 --> 00:39:15 decade old now that set. What are our very,
00:39:15 --> 00:39:17 uh, contemporary scientific, mathematical
00:39:17 --> 00:39:19 definitions of the habitable zone, um, that
00:39:19 --> 00:39:22 people use for their papers, and they take
00:39:22 --> 00:39:24 the flux from the star, take into account the
00:39:24 --> 00:39:27 different colours of the stars and, um, there
00:39:27 --> 00:39:29 are two versions. There's the optimistic and
00:39:29 --> 00:39:31 conservative versions, where the
00:39:31 --> 00:39:34 optimistic version is a wider set of
00:39:34 --> 00:39:35 distances and the conservative version is a
00:39:35 --> 00:39:38 smaller set of distances, but it effectively
00:39:38 --> 00:39:40 uses Venus and Mars as A roughinger edge in
00:39:40 --> 00:39:42 our solar system and then scales that window
00:39:42 --> 00:39:44 up and down depending on the kind of star
00:39:44 --> 00:39:47 you're around. But that illustrates
00:39:47 --> 00:39:49 immediately that this is an
00:39:49 --> 00:39:51 oversimplification, because you can do a
00:39:51 --> 00:39:53 thought experiment. Let's take our solar
00:39:53 --> 00:39:56 system. Venus is way too hot, Mars is way too
00:39:56 --> 00:39:58 cold and the Earth is just right. All well
00:39:58 --> 00:40:01 and good. Swap the Earth. Sorry, swap Mars
00:40:01 --> 00:40:03 and Venus around. If you put Venus where Mars
00:40:03 --> 00:40:06 is, Venus's thick atmosphere and greenhouse
00:40:06 --> 00:40:07 effect would mean it'd be warming up liquid
00:40:07 --> 00:40:09 water on the surface. It wouldn't have cooled
00:40:09 --> 00:40:11 as much as Mars. So Venus will be
00:40:12 --> 00:40:14 habitable on the surface, outside the
00:40:14 --> 00:40:17 habitable zone. Um, if you put m Mars, where
00:40:17 --> 00:40:18 Venus is, with its very thin and tenuous
00:40:18 --> 00:40:21 atmosphere, it doesn't have much greenhouse
00:40:21 --> 00:40:24 effect at all. Mars would potentially still
00:40:24 --> 00:40:27 be habitable where Venus is, when
00:40:27 --> 00:40:29 Venus isn't. And so that's immediately
00:40:29 --> 00:40:31 pointing that the storey is actually
00:40:31 --> 00:40:33 significantly more complex. Yeah. That
00:40:34 --> 00:40:37 you can't just say, let's calculate the
00:40:37 --> 00:40:38 habitable zone, let's calculate the
00:40:38 --> 00:40:41 equilibrium temperature on a planet, which is
00:40:41 --> 00:40:44 a temperature it would have if it didn't have
00:40:44 --> 00:40:46 a greenhouse effect, that it was a certain
00:40:46 --> 00:40:48 reflectivity and it was in equilibrium with
00:40:48 --> 00:40:50 the light coming in and light coming out. And
00:40:50 --> 00:40:52 if that temperature is from about minus 20
00:40:52 --> 00:40:54 upwards, it's probably warm enough for water
00:40:54 --> 00:40:55 because, well, you'll have a bit of an
00:40:55 --> 00:40:58 atmosphere. To me, that's never been enough.
00:40:58 --> 00:41:00 Now, the reason it's really important, at
00:41:00 --> 00:41:02 least from my perspective, is that, uh,
00:41:03 --> 00:41:05 finding planets is hard. We'll talk about
00:41:05 --> 00:41:08 that in another episode. But once you find
00:41:08 --> 00:41:11 the first of something, astronomy, history
00:41:11 --> 00:41:12 and probably every other form of scientific
00:41:12 --> 00:41:14 endeavour history tells us finding the first
00:41:14 --> 00:41:16 of something is hard. But once you've got
00:41:16 --> 00:41:18 one, you quickly find more and more as your
00:41:18 --> 00:41:20 technology gets better. Finding evidence of
00:41:20 --> 00:41:23 life on a planet that is similar to the Earth
00:41:24 --> 00:41:26 is fundamentally at least an order of
00:41:26 --> 00:41:29 magnitude, if not more harder than finding
00:41:29 --> 00:41:31 that planet was. So it'll take time for our
00:41:31 --> 00:41:33 technology to get good enough to search
00:41:33 --> 00:41:36 comfortably for life elsewhere. So initially
00:41:36 --> 00:41:38 that search is going to be very restricted
00:41:38 --> 00:41:40 because we've got limited resources. So
00:41:40 --> 00:41:42 you're only going to be able to look at a few
00:41:42 --> 00:41:45 planets aggressively at first, to try and
00:41:45 --> 00:41:47 tease out any indication of life.
00:41:47 --> 00:41:49 But you're going to have loads to choose
00:41:49 --> 00:41:52 from. How should you choose? Well, to me, it
00:41:52 --> 00:41:53 can't just be the habitable zone.
00:41:56 --> 00:41:58 Andrew Dunkley: Yeah, that's a valid point. Um,
00:41:59 --> 00:42:01 and we've reached a point where we've found
00:42:02 --> 00:42:04 thousands upon thousands of Exoplanets and
00:42:04 --> 00:42:06 counting like we haven't stopped. We're
00:42:06 --> 00:42:09 finding them more and more and more often of
00:42:09 --> 00:42:12 all different shapes of, uh, sizes. Um,
00:42:13 --> 00:42:16 some rocky planets, uh, they've been harder
00:42:16 --> 00:42:18 to find because they're usually much smaller
00:42:18 --> 00:42:21 and don't sort of indicate
00:42:21 --> 00:42:23 themselves like a gas giant does.
00:42:24 --> 00:42:26 But we're getting better at finding rocky,
00:42:26 --> 00:42:27 uh, planets.
00:42:27 --> 00:42:30 Um, I suppose the big
00:42:30 --> 00:42:33 question is, given how much we are finding,
00:42:34 --> 00:42:36 how do you identify prime targets for life?
00:42:37 --> 00:42:40 Jonti Horner: Yeah, and that is what the paper that I put
00:42:40 --> 00:42:42 together with Barry Jones back in 2010 was
00:42:42 --> 00:42:45 all about. So Barry was a very dear friend of
00:42:45 --> 00:42:47 mine. He was my boss when I moved to the open
00:42:47 --> 00:42:49 University from 2000 and 22 to 2009. I
00:42:49 --> 00:42:50 think he knew Fred Watson very well as well.
00:42:50 --> 00:42:52 So you can always mention to Fred Watson that
00:42:52 --> 00:42:54 we talked about Barry. I started work at the
00:42:54 --> 00:42:57 Open University in 2006 on the day Barry was
00:42:57 --> 00:42:59 forced to retire by the government because
00:42:59 --> 00:43:02 he'd hit 67. So he hired me and promptly
00:43:02 --> 00:43:04 retired. But, um, he kept working anyway as
00:43:04 --> 00:43:07 emeritus professor and Barry and I
00:43:07 --> 00:43:09 did a lot of work on this during my time that
00:43:09 --> 00:43:11 Barry unfortunately passed away a little bit
00:43:11 --> 00:43:13 more than a decade ago. So he's fondly
00:43:13 --> 00:43:15 remembered. I organise a, an award in the UK
00:43:15 --> 00:43:18 in his memory every couple of years. What
00:43:18 --> 00:43:21 we did in this 2010 paper was
00:43:22 --> 00:43:24 to essentially have the thought process we
00:43:24 --> 00:43:27 just outlined. So we're going to have a huge
00:43:27 --> 00:43:29 number of potential exo Earths, planets that
00:43:29 --> 00:43:32 could potentially be Earth like that could be
00:43:32 --> 00:43:35 places to look for life. But we're only going
00:43:35 --> 00:43:36 to be able to search a, ah, handful of them
00:43:36 --> 00:43:39 initially. So what should we do to select the
00:43:39 --> 00:43:41 best target? Now obviously the
00:43:41 --> 00:43:44 closer the planet's host star is to the solar
00:43:44 --> 00:43:46 system, the easier the observations will be.
00:43:46 --> 00:43:49 That's just a fundamental thing of if you're
00:43:49 --> 00:43:50 twice as far away, we only receive a quarter
00:43:50 --> 00:43:53 as much light from you. But also if you're
00:43:53 --> 00:43:55 twice as far away, the separation between the
00:43:55 --> 00:43:57 planet and the star on the sky will be half
00:43:57 --> 00:44:00 as much because the angle gets
00:44:00 --> 00:44:01 smaller the further away you go. Essentially
00:44:02 --> 00:44:03 we, uh, will want targets that are far enough
00:44:03 --> 00:44:05 from the star in the sky that with future
00:44:05 --> 00:44:06 missions like potentially the Habitable
00:44:06 --> 00:44:09 Worlds Observatory, we can separate the light
00:44:09 --> 00:44:11 from the planet from the light from the star.
00:44:11 --> 00:44:14 So probably even more important than the
00:44:14 --> 00:44:16 habitable zone, um, is this proximity thing.
00:44:16 --> 00:44:19 The planets in the main found by the Kepler
00:44:19 --> 00:44:21 space telescope won't be suitable for this
00:44:21 --> 00:44:23 search because they're mainly very far from
00:44:23 --> 00:44:26 the sun. And so therefore they'll be very
00:44:26 --> 00:44:27 hard to study. We want to look locally,
00:44:27 --> 00:44:30 that's a given. But
00:44:30 --> 00:44:32 we want to look for places where there is the
00:44:32 --> 00:44:34 possibility of liquid water on the surface
00:44:35 --> 00:44:37 because that means that the life will be in
00:44:37 --> 00:44:38 contact with the atmosphere and that might
00:44:38 --> 00:44:40 generate a signature we can detect in the
00:44:40 --> 00:44:42 atmosphere. And that's where the habitable
00:44:42 --> 00:44:45 zone comes from. But there's actually much
00:44:45 --> 00:44:47 more to it than that, I think, and I'm far
00:44:47 --> 00:44:48 from able to give an exhaustive list because
00:44:48 --> 00:44:51 I'm not an expert in, uh, all areas of
00:44:51 --> 00:44:53 astronomy. But we decided to put together a
00:44:53 --> 00:44:56 review paper which, about 32
00:44:56 --> 00:44:59 pages long, probably a little bit outdated
00:44:59 --> 00:45:01 now because science has moved forward, but
00:45:01 --> 00:45:04 was saying, effectively you can't just use a
00:45:04 --> 00:45:07 habitable zone. We need to think about
00:45:07 --> 00:45:09 all of the different factors that can
00:45:09 --> 00:45:10 contribute to make a planet more or less
00:45:10 --> 00:45:13 suitable for life. Now, many of these have
00:45:13 --> 00:45:15 been in the past suggested as that on off
00:45:15 --> 00:45:17 switch. And I do think that they're more
00:45:17 --> 00:45:18 sliders, like the numbers in the Drake
00:45:18 --> 00:45:21 equation or sliders on a mixing desk. But
00:45:21 --> 00:45:22 there are a lot of different things that have
00:45:22 --> 00:45:24 been suggested and as I dug into the paper,
00:45:25 --> 00:45:26 there were even more than I thought of. You
00:45:26 --> 00:45:29 can broadly break them down m into four
00:45:29 --> 00:45:32 areas. The first is galactic influences.
00:45:32 --> 00:45:35 So the impact of the galaxy itself, where you
00:45:35 --> 00:45:37 are in the galaxy, stuff like that, you've
00:45:37 --> 00:45:39 then got stellar influences, so the role of
00:45:39 --> 00:45:42 the star. You've got the planetary system and
00:45:42 --> 00:45:44 then you've got the planet itself. So they're
00:45:44 --> 00:45:46 the kind of four broad areas, the
00:45:46 --> 00:45:49 galactic influences. One is probably the
00:45:49 --> 00:45:50 least useful and the least well constrained.
00:45:50 --> 00:45:53 But the idea of the galactic influence is
00:45:53 --> 00:45:55 tied a bit to a theory that's been put
00:45:55 --> 00:45:57 forward by a few people called the Galactic
00:45:57 --> 00:46:00 Habitable Zone. It's an idea that
00:46:00 --> 00:46:03 ties back to the origin of stars and planets
00:46:03 --> 00:46:05 and also to the dangers that are experienced
00:46:05 --> 00:46:07 because of your environment. The idea that as
00:46:07 --> 00:46:09 time goes on, the universe is becoming more
00:46:09 --> 00:46:12 metal rich and by that I mean enriched in
00:46:12 --> 00:46:14 everything other than hydrogen and helium,
00:46:14 --> 00:46:16 because generations of stars run their
00:46:16 --> 00:46:18 furnaces and turn the light elements to the
00:46:18 --> 00:46:20 heavy ones and put them back into the cosmos.
00:46:20 --> 00:46:22 You need a certain amount of heavy elements
00:46:22 --> 00:46:24 to form planets like the Earth and to have
00:46:24 --> 00:46:26 the carbon, nitrogen, phosphorus for life.
00:46:27 --> 00:46:29 So as time goes on, the universe getting more
00:46:29 --> 00:46:32 enriched is a good thing. But there's also
00:46:32 --> 00:46:34 possibilities that too much enrichment will
00:46:34 --> 00:46:36 change the chemistry or it will make planet
00:46:36 --> 00:46:38 formation too easy. There's all sorts there,
00:46:38 --> 00:46:40 so you might have a sweet spot from that side
00:46:40 --> 00:46:43 of things. Now in the middle of the galaxy,
00:46:43 --> 00:46:46 star formation occurs at a more rapid pace
00:46:46 --> 00:46:48 and stars live and die quicker. So you get
00:46:48 --> 00:46:51 faster change in the abundance of
00:46:51 --> 00:46:54 materials. So you can imagine we have this
00:46:54 --> 00:46:56 concept in astronomy called metallicity,
00:46:56 --> 00:46:58 which is the amount. It's usually measured in
00:46:58 --> 00:47:00 the amount of hydrogen compared to the amount
00:47:00 --> 00:47:03 of iron in a star. And that gives you a
00:47:03 --> 00:47:05 number on a logarithmic scale. And that is an
00:47:05 --> 00:47:08 approximation to when the star formed and how
00:47:08 --> 00:47:10 enriched the world was at the time. And as
00:47:10 --> 00:47:12 time goes on, things get more and more metal
00:47:12 --> 00:47:14 rich within our galaxy. You'd expect there to
00:47:14 --> 00:47:16 be a gradient in this, so the things near the
00:47:16 --> 00:47:18 middle will be much more enriched in heavy
00:47:18 --> 00:47:19 elements of things, things near the outer
00:47:19 --> 00:47:21 edge. And there's probably sweet spot in the
00:47:21 --> 00:47:24 middle that moves outwards over time where
00:47:24 --> 00:47:26 conditions to form planets like the Earth,
00:47:26 --> 00:47:27 uh, and planetary systems like the solar
00:47:27 --> 00:47:30 system are perfect. So that's part of the
00:47:30 --> 00:47:32 galactic habitable zone idea. But the other
00:47:32 --> 00:47:35 idea is that if you're too close in and the
00:47:35 --> 00:47:37 stellar density is too high, eventually the
00:47:37 --> 00:47:39 stellar density gets, uh, so high that the
00:47:39 --> 00:47:41 likelihood of life being exterminated by
00:47:41 --> 00:47:43 nearby supernovae or planetary systems being
00:47:43 --> 00:47:46 stripped and disrupted becomes too high. So
00:47:46 --> 00:47:48 there's always been this idea that location
00:47:48 --> 00:47:50 within the galaxy is important.
00:47:51 --> 00:47:54 The challenge to that is twofold. Firstly,
00:47:54 --> 00:47:56 the proximity argument. We're gonna have to
00:47:56 --> 00:47:59 look at stars that are very nearby, which are
00:47:59 --> 00:48:00 all at the same distance from in the middle
00:48:00 --> 00:48:03 of the galaxy as we are. So where you are in
00:48:03 --> 00:48:06 the galaxy won't realistically impact this
00:48:06 --> 00:48:07 search because we're going to be looking
00:48:07 --> 00:48:10 locally. The other thing so is that stars
00:48:10 --> 00:48:12 have a huge degree of mobility. There was a
00:48:12 --> 00:48:14 recent storey talking about finding solar
00:48:14 --> 00:48:16 twin stars that have the same chemistry as
00:48:16 --> 00:48:19 the sun, that may have formed with the sun,
00:48:19 --> 00:48:22 and a suggestion that the sun and other stars
00:48:22 --> 00:48:24 may have formed as much as 10 light years
00:48:24 --> 00:48:26 nearer the middle of the galaxy than we are
00:48:26 --> 00:48:28 now. Stars are getting scattered inwards and
00:48:28 --> 00:48:30 outwards. So seeing a star here now doesn't
00:48:30 --> 00:48:32 imply that it's always been here.
00:48:33 --> 00:48:33 Andrew Dunkley: Yeah.
00:48:33 --> 00:48:36 Jonti Horner: So the galactic influences, I'm not going to
00:48:36 --> 00:48:38 go into really any more than that, but it's
00:48:38 --> 00:48:40 worth knowing that they're there, there. It's
00:48:40 --> 00:48:41 worth knowing that it's a point of discussion
00:48:41 --> 00:48:42 and that there is good research going on
00:48:42 --> 00:48:45 about this. It's really interesting area, but
00:48:45 --> 00:48:47 it doesn't, I think, impact our initial
00:48:47 --> 00:48:49 search for life, because we're going to be
00:48:50 --> 00:48:52 searching our local area. So it's a bit like
00:48:52 --> 00:48:54 me saying, I Want to search for signs of life
00:48:54 --> 00:48:57 on Earth, It's a lot easier for me to search
00:48:57 --> 00:49:00 in Kingstorp, where I live, than to search in
00:49:00 --> 00:49:02 Mumbai or in London. Places like this,
00:49:02 --> 00:49:05 you've got to look locally. Now, talking
00:49:05 --> 00:49:06 about that, you know, what would I expect to
00:49:06 --> 00:49:09 find? I'm, you know, the people in Kingsop
00:49:09 --> 00:49:11 have not all, but many of them have a similar
00:49:11 --> 00:49:13 background to me, formed in similar ways with
00:49:13 --> 00:49:16 similar cultural, the rest of it. So
00:49:16 --> 00:49:18 this is not a great analogy, I
00:49:18 --> 00:49:20 admit, but we've got to look locally. So the
00:49:20 --> 00:49:22 galactic influencer stuff is
00:49:23 --> 00:49:26 interesting, but I wouldn't say it
00:49:26 --> 00:49:28 is a big factor, but it's worth. Okay, I
00:49:28 --> 00:49:29 guess.
00:49:30 --> 00:49:31 Andrew Dunkley: So that leads us on to,
00:49:32 --> 00:49:35 um, I don't know, finding the right
00:49:35 --> 00:49:38 targets. Uh, and, and if we do find
00:49:38 --> 00:49:41 those targets, what, what do
00:49:41 --> 00:49:43 we do then to look for potential
00:49:43 --> 00:49:45 life on those targets?
00:49:45 --> 00:49:47 Jonti Horner: Absolutely. And that's a very hard question.
00:49:47 --> 00:49:48 Now, in terms of finding the right targets,
00:49:48 --> 00:49:50 there's a lot that comes into it from the
00:49:50 --> 00:49:52 star itself. Now,
00:49:53 --> 00:49:56 stars live very long lives.
00:49:56 --> 00:49:58 First question then is, how old is a star?
00:49:58 --> 00:50:00 Now, if we look at life on Earth, the oldest
00:50:00 --> 00:50:02 star fossils on Earth that are widely
00:50:02 --> 00:50:04 accepted are about three and a half thousand
00:50:04 --> 00:50:06 million years old, are in the Pilbara, which
00:50:06 --> 00:50:08 is about a billion years after the Earth, uh,
00:50:08 --> 00:50:10 formed. There are some that are older that
00:50:10 --> 00:50:13 are still controversial, possibly as old as 4
00:50:13 --> 00:50:14 billion years. But if we take the 3 1/2
00:50:14 --> 00:50:17 billion years as a threshold and we do what
00:50:17 --> 00:50:19 we're doing with the liquid water thing, and
00:50:19 --> 00:50:20 we say we expect life to follow a similar
00:50:20 --> 00:50:23 path, to us, the fact that it took a billion
00:50:23 --> 00:50:25 years for life to get established enough to
00:50:25 --> 00:50:27 leave fossils we could find possibly means
00:50:27 --> 00:50:29 that it might have taken a similar length of
00:50:29 --> 00:50:30 time for that life to modify its environment
00:50:30 --> 00:50:33 enough to be detectable from elsewhere. So we
00:50:33 --> 00:50:35 can put an arbitrary kind of timer here
00:50:35 --> 00:50:38 saying that any planetary system younger
00:50:38 --> 00:50:41 than, say, a billion years may have planets
00:50:41 --> 00:50:42 that are suitable for life, but that life
00:50:42 --> 00:50:44 might have not had enough time to get
00:50:44 --> 00:50:47 established yet. So that might
00:50:47 --> 00:50:50 immediately say that's not as good a place to
00:50:50 --> 00:50:51 look as a star that is more like the edge of
00:50:51 --> 00:50:54 the sun, while life's had 4 billion years to
00:50:54 --> 00:50:56 get going. Now, tied to that is
00:50:56 --> 00:50:59 the fact that the lives of stars are very
00:50:59 --> 00:51:01 dependent on the mass. So the more massive a
00:51:01 --> 00:51:03 star is, the brighter it shines, but the
00:51:03 --> 00:51:06 shorter its life is. And at a very rough
00:51:06 --> 00:51:08 level, this number varies a little bit
00:51:08 --> 00:51:09 depending on the mass of the star. But
00:51:09 --> 00:51:12 typically, the luminosity of a star Is
00:51:12 --> 00:51:14 proportional to its mass to the power four.
00:51:14 --> 00:51:16 So if you've got a star that is 10 times the
00:51:16 --> 00:51:18 mass of the sun, it will be roughly 10
00:51:18 --> 00:51:20 times brighter than the sun. But these
00:51:20 --> 00:51:22 stars are burning their own material. They're
00:51:22 --> 00:51:24 turning hydrogen to helium, and they're made
00:51:24 --> 00:51:26 of hydrogen. So a star that is 10 times the
00:51:26 --> 00:51:28 mass of the sun will only have 10 times as
00:51:28 --> 00:51:31 much fuel as the sun, but it's burning that
00:51:31 --> 00:51:33 fuel 10 times quicker, which means it'll
00:51:33 --> 00:51:36 run out a lot quicker. And what that means is
00:51:36 --> 00:51:37 that, uh, the more massive a star is, the
00:51:37 --> 00:51:40 longer, the shorter its life will be. And the
00:51:40 --> 00:51:42 less massive a star is, the longer its life
00:51:42 --> 00:51:45 will be. That means that beyond
00:51:45 --> 00:51:47 a certain, uh, stellar mass, the star will
00:51:47 --> 00:51:50 die before that billion year cutoff. So we
00:51:50 --> 00:51:52 can probably rule out the most massive stars.
00:51:52 --> 00:51:54 They'll just live fast, die young, and it's
00:51:54 --> 00:51:55 unlikely that life will get well enough
00:51:55 --> 00:51:58 established. On the flip side, the dim little
00:51:58 --> 00:52:00 red dwarfs will just go forever. You know,
00:52:00 --> 00:52:02 Proxima Centauri will still be trundling
00:52:02 --> 00:52:03 along in a trillion years when we're a decent
00:52:03 --> 00:52:06 memory. So they might be a good place to
00:52:06 --> 00:52:08 look. The challenge there though is, uh,
00:52:08 --> 00:52:11 those stars are, uh, quite active quite
00:52:11 --> 00:52:13 often. And um, to be in the habitable zone
00:52:13 --> 00:52:15 around them, you've got to be very close in
00:52:15 --> 00:52:16 because they're called little embers. You've
00:52:16 --> 00:52:18 got to snuggle up to the fire. So there's a
00:52:18 --> 00:52:20 lot of discussion about the fact that m dwarf
00:52:20 --> 00:52:22 planets, planets around these coolest,
00:52:22 --> 00:52:25 smallest stars are probably not ideal places
00:52:25 --> 00:52:27 to look for knife initially, few reasons. One
00:52:27 --> 00:52:29 is that activity and a lot of discussions
00:52:29 --> 00:52:31 that the activity of red dwarfs when they're
00:52:31 --> 00:52:33 young could scour a planet's atmosphere away.
00:52:33 --> 00:52:35 And that seems to have possibly been backed
00:52:35 --> 00:52:38 up with the Trappist 1 planets that all seem
00:52:38 --> 00:52:41 to be airless worlds. The other is that those
00:52:41 --> 00:52:43 planets, if they are close enough in to be
00:52:43 --> 00:52:45 warm enough for liquid water on the surface,
00:52:45 --> 00:52:47 would have to be tidally locked like the moon
00:52:47 --> 00:52:49 is to the Earth. Which means they'll keep one
00:52:49 --> 00:52:51 face permanently pointed towards the star and
00:52:51 --> 00:52:54 the other permanently away, which may make it
00:52:54 --> 00:52:56 harder to look for life on them. It might be
00:52:56 --> 00:52:57 the case, uh, any life would be on the
00:52:57 --> 00:52:59 sunward side. And that's kind of hard to
00:52:59 --> 00:53:01 observe because when that side is best
00:53:01 --> 00:53:04 presented to us, it's near the star. So
00:53:04 --> 00:53:06 that's challenging. Another thing that
00:53:06 --> 00:53:08 factors into it ties into something called
00:53:08 --> 00:53:10 the faint early sun paradox on Earth.
00:53:11 --> 00:53:13 The lives of
00:53:13 --> 00:53:16 stars. They shine brightly, their brightness
00:53:16 --> 00:53:18 Is measured good compared to their mass, but
00:53:18 --> 00:53:20 their brightness increases with time. Stars
00:53:20 --> 00:53:22 get more luminous as they age a little bit,
00:53:22 --> 00:53:24 and it's a slow process. But with the sun,
00:53:25 --> 00:53:27 we think the sun was 30 dimmer
00:53:28 --> 00:53:31 when it was born to how it is now. So
00:53:31 --> 00:53:33 that means the Earth at the time got 30% less
00:53:33 --> 00:53:35 energy, which would have put it, with its
00:53:35 --> 00:53:38 current atmosphere, too cold to support
00:53:38 --> 00:53:41 life. Um, that was offset by the
00:53:41 --> 00:53:43 fact we had a very different atmosphere than
00:53:43 --> 00:53:46 in a significant greenhouse effect,
00:53:46 --> 00:53:48 which was lessened due to the influence of
00:53:48 --> 00:53:51 life stripping out carbon dioxide,
00:53:51 --> 00:53:53 particularly from the atmosphere, and keeping
00:53:53 --> 00:53:55 us mostly there and thereabouts. But what
00:53:55 --> 00:53:57 that means is that if we find a planet now
00:53:58 --> 00:54:00 and that planet is near the outer edge of the
00:54:00 --> 00:54:02 habitable zone, um, everybody will go, well,
00:54:02 --> 00:54:03 it's in the habitable zone. That's great.
00:54:04 --> 00:54:06 Whereas my question would then be, but how
00:54:06 --> 00:54:08 long has it been in the habitable zone?
00:54:08 --> 00:54:10 Because when the SAR was younger, it was a
00:54:10 --> 00:54:13 little bit dimmer. The habitable zone would
00:54:13 --> 00:54:14 have been closer in, and that planet might
00:54:14 --> 00:54:16 well have been outside it. So I don't
00:54:16 --> 00:54:18 necessarily think that that 1 billion year
00:54:18 --> 00:54:20 clock would start until the planet was in the
00:54:20 --> 00:54:22 habitable zone. So we'll probably then be
00:54:22 --> 00:54:25 able to rule some planets out on the
00:54:25 --> 00:54:28 basis of the fact that they could be
00:54:28 --> 00:54:29 in the habitable zone, uh, now, but they
00:54:29 --> 00:54:32 haven't been full long enough. Yeah, the star
00:54:32 --> 00:54:34 has all these effects. Never mind the fact
00:54:34 --> 00:54:36 that astronomers often joke that three out of
00:54:36 --> 00:54:38 every two stars are in a multiple star
00:54:38 --> 00:54:41 system. Them multiple, um, stars are
00:54:41 --> 00:54:43 very, very common. And uh, that adds a whole
00:54:43 --> 00:54:46 extra level of complexity, Both to
00:54:46 --> 00:54:48 the understanding of the lives of the planets
00:54:48 --> 00:54:50 in those stars, but also in our ability to
00:54:50 --> 00:54:52 study them. Because you've got more than one
00:54:52 --> 00:54:54 stars like to factor rain all close together.
00:54:55 --> 00:54:57 It's much nastier and much more complicated.
00:54:58 --> 00:55:00 So there's a lot of ways that the stars can
00:55:00 --> 00:55:01 factor in. And I think that's only a, ah,
00:55:02 --> 00:55:04 very, very broad brushstrokes view, but
00:55:04 --> 00:55:07 you can see how. So what I'm thinking is you
00:55:07 --> 00:55:10 can bring in all these different ideas and
00:55:10 --> 00:55:13 halve them as a slider. This kind of star
00:55:13 --> 00:55:14 could have planets around it with life, but
00:55:14 --> 00:55:17 it's not as good a target as this one. Now,
00:55:17 --> 00:55:19 everybody could build their own algorithm out
00:55:19 --> 00:55:20 of this, But I'd like to think that when
00:55:20 --> 00:55:22 we're trying to pick the target, you take
00:55:22 --> 00:55:25 into account the star that it's going around,
00:55:25 --> 00:55:28 how active it is. Is it a single star, Is
00:55:28 --> 00:55:30 it old enough, all these kind of factors
00:55:31 --> 00:55:33 and Then you can start looking at the
00:55:33 --> 00:55:35 planetary system that it's in. And there's a
00:55:35 --> 00:55:37 lot to talk about there, I think.
00:55:37 --> 00:55:40 Andrew Dunkley: Yes, absolutely. Uh, and in
00:55:40 --> 00:55:42 our next, um, ah, special,
00:55:43 --> 00:55:46 um, between Q and A episodes, we will,
00:55:46 --> 00:55:49 um, look more into, um, the, the
00:55:49 --> 00:55:50 planet side of things.
00:55:50 --> 00:55:53 I, I guess just to conclude, um, I'll throw
00:55:53 --> 00:55:56 one at you. Um, and, and this answer is
00:55:56 --> 00:55:58 always different, depending on who you ask.
00:55:58 --> 00:56:00 But, uh, we. What do you think the odds are
00:56:00 --> 00:56:03 that we will find some form of life?
00:56:05 --> 00:56:08 Jonti Horner: I'm an optimist. I think the answer to
00:56:08 --> 00:56:10 it will be yes, we will find some sort of
00:56:10 --> 00:56:12 life. I think the harder question is when?
00:56:13 --> 00:56:16 Now, if we find life in
00:56:16 --> 00:56:18 a million years time when we're not even
00:56:18 --> 00:56:19 human anymore, but we've hung around, we've
00:56:19 --> 00:56:22 managed to survive. That's not very edifying
00:56:22 --> 00:56:23 for me and you because it's long time to
00:56:23 --> 00:56:25 work. But as I said earlier on, I don't think
00:56:25 --> 00:56:27 it's a question of if, it's a question of, of
00:56:27 --> 00:56:30 when. Because I find it vanishingly
00:56:30 --> 00:56:32 improbable for us to be the only
00:56:33 --> 00:56:36 system with life. And it's a numbers game for
00:56:36 --> 00:56:38 me. You know, we've got a galaxy with between
00:56:38 --> 00:56:40 200 and 400 million
00:56:40 --> 00:56:43 stars. There are more galaxies in the
00:56:43 --> 00:56:46 visible universe, certainly than there are
00:56:46 --> 00:56:49 planets in our galaxy, probably more than
00:56:49 --> 00:56:51 there are grains of sand in our galaxy. All
00:56:51 --> 00:56:53 of them with hundreds of thousands of
00:56:53 --> 00:56:55 millions of stars to say that
00:56:55 --> 00:56:58 out of. If you run the numbers, you get
00:56:58 --> 00:57:00 sextillions, septillions, even
00:57:00 --> 00:57:03 octillions bonkersly full
00:57:03 --> 00:57:06 on numbers of planets out there that
00:57:06 --> 00:57:09 were the only place that got life. That tells
00:57:09 --> 00:57:11 you that life is effectively impossible and
00:57:11 --> 00:57:14 we're a fluke. Now, that
00:57:14 --> 00:57:16 could be the case. If that's the case, what
00:57:16 --> 00:57:18 we've got here on Earth becomes even more
00:57:18 --> 00:57:20 precious. And there is an even greater
00:57:20 --> 00:57:23 incentive for us to keep an eye on what
00:57:23 --> 00:57:25 we're doing so that Earth is still capable of
00:57:25 --> 00:57:28 hurting life in the future. But I think in
00:57:28 --> 00:57:30 reality, life will actually be more common
00:57:30 --> 00:57:32 than that. And you don't need to be much more
00:57:32 --> 00:57:34 common than that for life to be abundant in
00:57:34 --> 00:57:37 the galaxy. Let's imagine that life is
00:57:37 --> 00:57:40 found on one planet in one
00:57:40 --> 00:57:43 billion. That's billion with a B. So one in a
00:57:43 --> 00:57:45 thousand million. Now we're finding that on
00:57:45 --> 00:57:47 average, all stars have planets, probably
00:57:47 --> 00:57:49 have a number of planets. So if we say
00:57:49 --> 00:57:51 roughly there are 10 planets per star, there
00:57:51 --> 00:57:54 will be 4,4 trillion planets in our galaxy.
00:57:54 --> 00:57:57 If one in a billion had life on
00:57:57 --> 00:58:00 it, that will mean there were 4 inhabited
00:58:00 --> 00:58:03 planets in our galaxy. Not a
00:58:03 --> 00:58:04 big number. The nearest one will be so far
00:58:04 --> 00:58:06 away. In that case we wouldn't find life for
00:58:06 --> 00:58:09 a long time. But life could be common
00:58:09 --> 00:58:11 and we still wouldn't find it. The more you
00:58:11 --> 00:58:14 increase that likelihood of life, the nearer
00:58:14 --> 00:58:16 uh, the nearest examples will be in, the
00:58:16 --> 00:58:18 sooner we'll find it. And that's why I think
00:58:18 --> 00:58:20 proximity will tell us a lot about the
00:58:20 --> 00:58:23 probability of life and that
00:58:23 --> 00:58:26 if we find life, the next step is to
00:58:26 --> 00:58:28 figure out we are not alone, we know we're
00:58:28 --> 00:58:31 not alone, how common is life. Now the other
00:58:31 --> 00:58:33 thing I think factors into it, I think is a
00:58:33 --> 00:58:35 lovely kind of sci fi thing to discuss all
00:58:35 --> 00:58:36 the way through. You mentioned early on
00:58:36 --> 00:58:39 carbon based life and technologically
00:58:39 --> 00:58:42 advanced life and we drifted away. The
00:58:42 --> 00:58:45 one place where I think that life that is
00:58:45 --> 00:58:46 different to us is something we could
00:58:46 --> 00:58:49 possibly find is silicon based life.
00:58:50 --> 00:58:53 Now the reason for that is not from
00:58:53 --> 00:58:56 the point of view of um, silicon
00:58:56 --> 00:58:59 people who have evolved in the way we have
00:58:59 --> 00:59:01 done. I'm thinking more kind of second
00:59:01 --> 00:59:03 generation life. Now our exploration of the
00:59:03 --> 00:59:06 solar system is done by our robot envoys and
00:59:06 --> 00:59:08 we're sending them near enough to harm that
00:59:08 --> 00:59:11 we can tell them what to do. But we are
00:59:11 --> 00:59:14 developing to certain controversy at the
00:59:14 --> 00:59:15 current time. We're developing a greater and
00:59:15 --> 00:59:17 greater ability to visualise, develop things
00:59:17 --> 00:59:19 that can make decisions for themselves
00:59:19 --> 00:59:21 without human input, things like AI and other
00:59:21 --> 00:59:24 systems. And if we get to the point where we
00:59:24 --> 00:59:26 want to explore around other
00:59:26 --> 00:59:29 stars, we'll need to develop spacecraft that
00:59:29 --> 00:59:31 have enough autonomy to make their own
00:59:31 --> 00:59:34 decisions. You go back to the idea and I
00:59:34 --> 00:59:35 don't know what's happened to it in recent
00:59:35 --> 00:59:36 years, but the idea of Project Starshot,
00:59:36 --> 00:59:38 where they made a little spacecraft, shot
00:59:38 --> 00:59:40 them off with laser, then they got to proxima
00:59:40 --> 00:59:43 Centauri in 25 years, travelling at a fifth
00:59:43 --> 00:59:45 of the speed of light. You do that,
00:59:46 --> 00:59:48 they get to Proxima Centauri. If they've got
00:59:48 --> 00:59:49 to ask us what to do, they send a signal to
00:59:49 --> 00:59:52 us. Takes four and a bit years to get here,
00:59:52 --> 00:59:54 takes five years to get back, and by the time
00:59:54 --> 00:59:55 it reaches them, they're a light year beyond
00:59:55 --> 00:59:57 the system and it's like, well too late. So
00:59:57 --> 00:59:59 we have to give them a certain level of
00:59:59 --> 01:00:01 autonomy. And the more complex their mission
01:00:01 --> 01:00:03 is going to be, the more autonomous it have
01:00:03 --> 01:00:05 to be. Which leads to uh, the very science
01:00:05 --> 01:00:08 fiction idea that when we move out beyond the
01:00:08 --> 01:00:10 solar system, if we move out beyond the solar
01:00:10 --> 01:00:13 system, we will be preceded by
01:00:13 --> 01:00:15 a wave of life that is not us,
01:00:16 --> 01:00:18 that is our life that has a
01:00:18 --> 01:00:21 creator. That creator is humanity. That is
01:00:21 --> 01:00:23 silicon based life that we send out, whether
01:00:23 --> 01:00:25 they're von Neumann machines, whether they
01:00:25 --> 01:00:28 are incredibly advanced AI machines without
01:00:28 --> 01:00:31 the capacity to reproduce themselves. We
01:00:31 --> 01:00:33 will send out artificially
01:00:34 --> 01:00:37 built silicon life forms. And again,
01:00:37 --> 01:00:40 that's a lovely, fairly lost X
01:00:40 --> 01:00:42 sci fi series called the Bobby Verse,
01:00:42 --> 01:00:45 um, which follows that kind of idea in terms
01:00:45 --> 01:00:48 of future Earth. Well, guy
01:00:48 --> 01:00:50 in the current day dies, but has invested in
01:00:50 --> 01:00:53 cryogenics and his head is frozen and he
01:00:53 --> 01:00:55 wakes up and he's essentially put into a Van
01:00:55 --> 01:00:57 Neumann machine and shot out into the stars.
01:00:58 --> 01:00:59 And that, that's a really interesting one
01:00:59 --> 01:01:01 because it's silicon based life that is also
01:01:01 --> 01:01:03 human. Let me figure that one out. But it's
01:01:03 --> 01:01:06 good fun following again that very
01:01:06 --> 01:01:08 dangerous assumption that other life would
01:01:08 --> 01:01:10 follow the same path where we follow. And it
01:01:10 --> 01:01:12 seems like we are going down this AI and
01:01:12 --> 01:01:15 increasing complexity and increasing autonomy
01:01:15 --> 01:01:18 route. You'd then argue that other species
01:01:18 --> 01:01:20 sending out craft into the galaxy
01:01:20 --> 01:01:23 would send out autonomous
01:01:23 --> 01:01:25 intelligent silicon machines
01:01:26 --> 01:01:28 before they send themselves out. And
01:01:28 --> 01:01:30 therefore, you know, I think we're more
01:01:30 --> 01:01:32 likely, if we're ever to bump into aliens, to
01:01:32 --> 01:01:34 run into one of these probes or one of these
01:01:34 --> 01:01:36 machines rather than the aliens themselves. I
01:01:36 --> 01:01:38 think there is a very real chance that if we
01:01:38 --> 01:01:41 find intelligent advanced life, it could be
01:01:41 --> 01:01:43 silicon based rather than carbon based. But
01:01:43 --> 01:01:45 it's silicon based life that was created by
01:01:45 --> 01:01:48 carbon based life, which I mean,
01:01:48 --> 01:01:50 leads to really interesting questions about
01:01:50 --> 01:01:52 philosophy and religion and all those kind of
01:01:52 --> 01:01:54 things which are not my forte. But you know,
01:01:54 --> 01:01:56 it does ask interesting questions about
01:01:56 --> 01:01:58 origin and creation when you think about it
01:01:58 --> 01:02:00 from the context of that, which is one of the
01:02:00 --> 01:02:02 things that driven, like I said, a lot of
01:02:02 --> 01:02:04 wonderful and wonderfully entertaining sci fi
01:02:04 --> 01:02:05 over the years.
01:02:05 --> 01:02:08 Andrew Dunkley: Yeah, yeah, as you said earlier, we could, we
01:02:08 --> 01:02:10 could talk about this for a week, but we
01:02:10 --> 01:02:13 can't. Um, but uh, I
01:02:13 --> 01:02:16 do uh, want to direct people to your paper if
01:02:16 --> 01:02:18 uh, people are interested in reading your
01:02:18 --> 01:02:21 paper from 2010. Uh, it's
01:02:21 --> 01:02:24 uh, called Determining Habitability. Which
01:02:24 --> 01:02:27 exo Earths, uh, should we search for for
01:02:27 --> 01:02:30 life? And you can find it on the ARXIV
01:02:30 --> 01:02:31 website, is that right, John?
01:02:31 --> 01:02:33 Jonti Horner: Yeah. So that was published in the
01:02:33 --> 01:02:35 International Journal of Astrobiology in
01:02:35 --> 01:02:36 2010. So the ones who want the kind of
01:02:36 --> 01:02:38 scientific reference, it's International
01:02:38 --> 01:02:41 Journal of Astrobiology, Volume 9, page
01:02:41 --> 01:02:44 273 onwards. But um, if
01:02:44 --> 01:02:46 you find it on NASA rads, it'll give you the
01:02:46 --> 01:02:48 archive link which is the pre print Version,
01:02:48 --> 01:02:51 which basically means it's in my formatting
01:02:51 --> 01:02:53 rather than journal formatting. And this is,
01:02:54 --> 01:02:56 it's actually a, uh, handy aside that I'm
01:02:56 --> 01:02:58 sure, as we mentioned before, the
01:02:59 --> 01:03:01 way that a lot of science
01:03:01 --> 01:03:04 works has led to the creation of the most
01:03:04 --> 01:03:06 profitable, um, um, and
01:03:06 --> 01:03:09 problematic, um, companies in the world,
01:03:09 --> 01:03:11 which are the publishing companies. And so
01:03:11 --> 01:03:13 the way a scientist works is we do all this
01:03:13 --> 01:03:15 work, da da da da da. Hooray, hooray, hooray.
01:03:15 --> 01:03:17 We then write a paper to tell the world about
01:03:17 --> 01:03:19 it. We send that off to a journal who
01:03:19 --> 01:03:21 gets another scientist to volunteer their
01:03:21 --> 01:03:23 time, unpaid for free, to referee it.
01:03:24 --> 01:03:27 Then they're charged, typically the scientist
01:03:27 --> 01:03:28 who's written that paper money to publish
01:03:28 --> 01:03:31 that paper for them and then charge everybody
01:03:31 --> 01:03:33 for the privilege of reading it. So if I want
01:03:33 --> 01:03:35 the journal, if I want to read the journal
01:03:35 --> 01:03:37 versions of my papers. Fortunately,
01:03:37 --> 01:03:39 universities have paid access to a lot of
01:03:39 --> 01:03:41 journals, but I'm fundamentally paying to
01:03:41 --> 01:03:44 read my own work. And this is
01:03:45 --> 01:03:47 not ideal. Big deal. I think partly because
01:03:47 --> 01:03:48 as a scientist, you know, I'm paid by
01:03:48 --> 01:03:51 taxpayers money, people are paying me to do
01:03:51 --> 01:03:54 this work. To me, it is really important that
01:03:54 --> 01:03:55 they know what we're doing, they know what
01:03:55 --> 01:03:57 they're getting for their money. And, um,
01:03:57 --> 01:03:59 part of that is be a science communicator.
01:03:59 --> 01:04:00 And I encourage any scientists or budding
01:04:00 --> 01:04:03 scientists, don't refocus on the science.
01:04:03 --> 01:04:04 Focus on communication as well, because if
01:04:04 --> 01:04:06 you do science but can't communicate it, no
01:04:06 --> 01:04:09 one will know what you've done. But to get
01:04:09 --> 01:04:12 around that, what we do in astronomy and
01:04:12 --> 01:04:14 what many disciplines do, is that, uh, we put
01:04:14 --> 01:04:17 preprints up on a publicly
01:04:17 --> 01:04:19 accessible free place. And it's in astronomy,
01:04:19 --> 01:04:21 it's just accepted that with very rare
01:04:21 --> 01:04:24 exceptions, journals will let you do this. So
01:04:24 --> 01:04:26 when we get our paper and we've written it,
01:04:27 --> 01:04:29 some disciplines in astronomy will put the
01:04:29 --> 01:04:31 paper up on the archive when it's submitted.
01:04:31 --> 01:04:33 Some will wait until it's accepted by the
01:04:33 --> 01:04:35 journal when it's refereed. I've always
01:04:35 --> 01:04:37 waited till acceptance, but occasionally if
01:04:37 --> 01:04:38 you've made a big discovery, you want to stop
01:04:38 --> 01:04:40 somebody scooping you to you, you put it up
01:04:40 --> 01:04:42 at submission. There's a growing effort by
01:04:42 --> 01:04:44 scientists to put it up at submission, to
01:04:44 --> 01:04:46 actively solicit feedback from the community
01:04:46 --> 01:04:48 to improve the work, which is good. But those
01:04:48 --> 01:04:50 papers go upon arXiv.
01:04:51 --> 01:04:53 ArXiv, yeah. Um, be very
01:04:53 --> 01:04:56 careful. There is another platform out
01:04:56 --> 01:04:59 there where the letters in ARXIV are shifted
01:04:59 --> 01:05:01 around, which is where a community of people
01:05:01 --> 01:05:04 who espouse Ideas that are not scientifically
01:05:04 --> 01:05:07 verifiable will put their work, uh, and
01:05:07 --> 01:05:08 publish their own little papers. It's a
01:05:08 --> 01:05:10 different thing. But ARXIV is a
01:05:10 --> 01:05:13 repository of free to view things. So if
01:05:13 --> 01:05:16 you are searching for papers, NASA's ADS
01:05:16 --> 01:05:18 system is wonderful. When you click on a
01:05:18 --> 01:05:21 given paper in there, most of them, but not
01:05:21 --> 01:05:22 all of them will have a line that says
01:05:22 --> 01:05:25 journal version or ADS version. But there'll
01:05:25 --> 01:05:27 also be a line that says preprint. And if you
01:05:27 --> 01:05:28 click on the preprint links, it will take you
01:05:28 --> 01:05:31 to the archive and allow you to read the
01:05:31 --> 01:05:33 paper for free. Just to be aware that that is
01:05:33 --> 01:05:36 a version some of the time before
01:05:36 --> 01:05:37 refereeing, most of the time after
01:05:37 --> 01:05:39 refereeing, but before publishing in edits
01:05:40 --> 01:05:42 effectively. So the link you've got to that
01:05:42 --> 01:05:45 is the pre print version of that paper. The
01:05:45 --> 01:05:47 other caution I give to people is that uh, it
01:05:47 --> 01:05:49 is 16 years old. So all of the areas I talk
01:05:49 --> 01:05:51 about in it have moved on. We've learned
01:05:51 --> 01:05:53 more, um, we can talk a bit more about it
01:05:53 --> 01:05:56 next time as well. But always when you read
01:05:56 --> 01:05:58 things, be conscious of the fact that that
01:05:58 --> 01:06:00 science, uh, is fluid. Science changes, our
01:06:00 --> 01:06:02 knowledge changes. I see just in the news
01:06:02 --> 01:06:05 recently, Jason Isaacs Isaacson,
01:06:05 --> 01:06:07 who's I think the head guy at Nashville at
01:06:07 --> 01:06:10 the minute, who's a wealthy multi billionaire
01:06:10 --> 01:06:13 type guy, um, is arguing that the US is
01:06:13 --> 01:06:15 wanting to strongly build a scientific case
01:06:15 --> 01:06:17 why Pluto should be restored as a planet
01:06:17 --> 01:06:19 because fundamentally we discovered it, so it
01:06:19 --> 01:06:21 should still be a planet. And Clyde Tomball
01:06:21 --> 01:06:22 would be turning in his grave.
01:06:24 --> 01:06:27 That is what it is. But it's, it is
01:06:27 --> 01:06:30 important to keep in mind that science
01:06:30 --> 01:06:33 is fluid, it moves. Whereas once something is
01:06:33 --> 01:06:35 published that's static, you know, it's a
01:06:35 --> 01:06:38 window on our knowledge at a time rather than
01:06:38 --> 01:06:41 necessarily the modern version. If I were
01:06:41 --> 01:06:43 to rewrite that paper now, there'd be
01:06:43 --> 01:06:46 advances of course, absolutely.
01:06:46 --> 01:06:49 Andrew Dunkley: But um, yes, um, I think we're trying to
01:06:49 --> 01:06:51 arrange to put the link on the show notes.
01:06:51 --> 01:06:53 I'll just have to remind Huw you about that.
01:06:53 --> 01:06:55 We might wrap it up there. Jonty. Fascinating
01:06:55 --> 01:06:58 topic and uh, it's one we get a heck of a lot
01:06:58 --> 01:07:01 of questions about. So, um, yeah, hopefully
01:07:01 --> 01:07:03 there's a, uh, bit of information in there to
01:07:03 --> 01:07:05 keep people's minds whirring.
01:07:06 --> 01:07:08 Johnty, thanks very much. We will, uh, see
01:07:08 --> 01:07:09 you again real soon.
01:07:09 --> 01:07:10 Jonti Horner: It's an absolute pleasure. Thank you for
01:07:10 --> 01:07:11 having me.
01:07:11 --> 01:07:13 Andrew Dunkley: Professor John Dee Horner, professor of
01:07:13 --> 01:07:15 Astrophysics at the University of Southern
01:07:15 --> 01:07:17 Queensland, standing in for Fred Watson
01:07:17 --> 01:07:20 Watson. And thanks to Huey in the studio. Uh,
01:07:20 --> 01:07:23 Huw couldn't be with us today. Um, he got,
01:07:23 --> 01:07:24 uh, a bit confused.
01:07:24 --> 01:07:24 Jonti Horner: We.
01:07:24 --> 01:07:26 Andrew Dunkley: We know of one planet where there is life.
01:07:27 --> 01:07:29 Huw thought we meant that he was the only
01:07:29 --> 01:07:32 life form on the planet, so he didn't see any
01:07:32 --> 01:07:34 need to turn up today. And from me, Andrew
01:07:34 --> 01:07:36 Dunkley, thanks for your company. We'll see
01:07:36 --> 01:07:38 you on the next episode of Space Nuts.
01:07:38 --> 01:07:41 Jonti Horner: Bye. Bye. You've been listening to
01:07:41 --> 01:07:42 the Space Nuts podcast,
01:07:44 --> 01:07:47 available at Apple Podcasts, Spotify,
01:07:47 --> 01:07:50 iHeartRadio or your favourite podcast
01:07:50 --> 01:07:51 player. You can also stream on
01:07:51 --> 01:07:53 demand@bytes.com.
01:07:53 --> 01:07:55 Andrew Dunkley: this has been another quality podcast
01:07:55 --> 01:07:57 production from bytes.um.com.