Astrobiology: The Search for Life Beyond Earth In this special edition of Space Nuts , hosts Andrew Dunkley and Professor Jonti Horner delve into the captivating field of astrobiology. With Professor Fred Watson away, Jonty brings his expertise to explore the complexities of life beyond our planet, the conditions necessary for its existence, and the ongoing quest to find it.
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.
For more Space Nuts, including our continuously updating newsfeed and to listen to all our episodes, visit our website. (https://www.spacenutspodcast.com/) Follow us on social media at SpaceNutsPod on Facebook, Instagram, and more. We love engaging with our community, so be sure to drop us a message or comment on your favourite platform.
If you’d like to help support Space Nuts and join our growing family of insiders for commercial-free episodes and more, visit spacenutspodcast.com/about (https://www.spacenutspodcast.com/about) .
Stay curious, keep looking up, and join us next time for more stellar insights and cosmic wonders. Until then, clear skies and happy stargazing.
Become a supporter of this podcast: https://www.spreaker.com/podcast/space-nuts-astronomy-insights-cosmic-discoveries--2631155/support (https://www.spreaker.com/podcast/space-nuts-astronomy-insights-cosmic-discoveries--2631155/support?utm_source=rss&utm_medium=rss&utm_campaign=rss) .
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
Episode link: https://play.headliner.app/episode/33420280?utm_source=youtube
00:00:00 --> 00:00:01 Hi there. Thanks for joining us again.
00:00:01 --> 00:00:04 This is Space Nuts, where we talk
00:00:04 --> 00:00:07 astronomy and space science. And my name
00:00:07 --> 00:00:09 is Andrew Dunley, your host. Great to
00:00:09 --> 00:00:11 have your company. Now, normally I'd be
00:00:11 --> 00:00:13 joined by Professor Fred Watson, but he
00:00:13 --> 00:00:16 is away visiting family at the moment.
00:00:16 --> 00:00:18 And because he was going to be away and
00:00:18 --> 00:00:20 then I'm going to be away and we tried
00:00:20 --> 00:00:22 to cram episodes in and uh we just we
00:00:22 --> 00:00:24 couldn't do enough in the amount of time
00:00:24 --> 00:00:27 we had, uh we invited Professor Jotty
00:00:27 --> 00:00:29 Horner to join us and uh we're going to
00:00:29 --> 00:00:30 do some specials. You might have heard
00:00:30 --> 00:00:33 the last one, uh which was very engaging
00:00:33 --> 00:00:35 and interesting and fascinating and
00:00:35 --> 00:00:39 long. Uh this time we we're going down a
00:00:39 --> 00:00:40 different road. We're going to focus the
00:00:40 --> 00:00:44 whole program on astro biology. Strap
00:00:44 --> 00:00:46 in. We'll do that right now.
00:00:46 --> 00:00:51 >> 15 seconds. Guidance is internal. 10 9
00:00:51 --> 00:00:53 Ignition sequence start.
00:00:53 --> 00:00:54 >> Space nuts.
00:00:54 --> 00:00:56 >> 5 4 3 2
00:00:56 --> 00:00:59 >> 1 2 3 4 5 5 4 3 2 1
00:00:59 --> 00:01:00 >> Space nuts.
00:01:00 --> 00:01:02 >> Astronauts report. It feels good.
00:01:02 --> 00:01:04 >> And here he is again. Professor of
00:01:04 --> 00:01:05 astrophysics at the University of
00:01:05 --> 00:01:08 Southern Queensland, Johnny her. Good
00:01:08 --> 00:01:08 day, Johnny.
00:01:08 --> 00:01:10 >> Good day. How are you going?
00:01:10 --> 00:01:13 >> I'm well. Good to see you again. And uh
00:01:13 --> 00:01:14 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 --> 00:01:22 chat, you sent me a paper that you wrote
00:01:22 --> 00:01:25 uh and published on the archive website.
00:01:25 --> 00:01:27 Uh it's um
00:01:27 --> 00:01:28 >> ancient.
00:01:28 --> 00:01:31 >> Yeah, it it's it's coming up on 16 years
00:01:31 --> 00:01:33 since you wrote that. But one of the
00:01:33 --> 00:01:36 interesting parts was uh look, it's been
00:01:36 --> 00:01:38 a couple of decades now that we've been
00:01:38 --> 00:01:40 finding exoplanets. And as technology
00:01:40 --> 00:01:42 improves, it's only a matter of time
00:01:42 --> 00:01:44 before we start finding Earthlike
00:01:44 --> 00:01:47 planets. And that's really going to make
00:01:47 --> 00:01:49 the search for life beyond our solar
00:01:49 --> 00:01:53 system really really interesting. So
00:01:53 --> 00:01:54 those 16 years have passed. Have we got
00:01:54 --> 00:01:57 the Have we got the equipment yet? I
00:01:57 --> 00:01:59 suspect we have. It depends where you're
00:01:59 --> 00:02:01 looking, I think. I mean, in terms of
00:02:01 --> 00:02:03 looking at the planets around other
00:02:03 --> 00:02:05 stars, we can now learn a lot more about
00:02:05 --> 00:02:07 them than we could 16 years ago when I
00:02:07 --> 00:02:10 wrote the paper. that particular paper,
00:02:10 --> 00:02:12 but we're still not there yet. And it's
00:02:12 --> 00:02:15 a perpetual thing. No matter how hard
00:02:15 --> 00:02:17 you work, there's always more to do. The
00:02:17 --> 00:02:18 other thing that goes along with it,
00:02:18 --> 00:02:20 which I think is worth saying right up
00:02:20 --> 00:02:22 at the very start, is that searching for
00:02:22 --> 00:02:24 life elsewhere is going to be one of the
00:02:24 --> 00:02:27 hardest things we've ever done. And
00:02:27 --> 00:02:29 absence of evidence is not necessarily
00:02:29 --> 00:02:33 evidence of absence. What I mean by that
00:02:33 --> 00:02:35 is we could in a remarkable turn of
00:02:35 --> 00:02:37 events in the next few months find life
00:02:37 --> 00:02:39 elsewhere. you know, that's kind of the
00:02:39 --> 00:02:42 ultimate extreme soonest possible. Um,
00:02:42 --> 00:02:44 very unlikely to happen. Alternatively,
00:02:44 --> 00:02:47 we might still be looking in a century.
00:02:47 --> 00:02:49 If we're still looking in a century,
00:02:49 --> 00:02:50 that doesn't mean that there isn't any
00:02:50 --> 00:02:53 life out there. But what it will suggest
00:02:54 --> 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
00:02:59 --> 00:03:01 elsewhere, that a it will be awesome
00:03:01 --> 00:03:02 because, hey, look, we found life
00:03:02 --> 00:03:03 elsewhere and we've answered the
00:03:03 --> 00:03:06 ultimate question. Are we alone?
00:03:06 --> 00:03:07 But the sooner we find life elsewhere,
00:03:07 --> 00:03:08 the other thing it's telling us is that
00:03:08 --> 00:03:10 life must be fairly common in the
00:03:10 --> 00:03:13 universe. The scarcer life is, the
00:03:13 --> 00:03:14 harder it will be to find and therefore
00:03:14 --> 00:03:17 the longer it will take us to find. And
00:03:17 --> 00:03:19 now the ultimate extreme of that is that
00:03:19 --> 00:03:20 this is the only place that there is
00:03:20 --> 00:03:24 life. And it'll be very hard to conclude
00:03:24 --> 00:03:26 that even if we were talking through a
00:03:26 --> 00:03:29 time warp in 10 years when humanity
00:03:29 --> 00:03:31 is taking its fledgling steps into the
00:03:31 --> 00:03:33 galaxy or whatever, if we haven't found
00:03:34 --> 00:03:35 life by then, we'll be confident that
00:03:35 --> 00:03:37 life is very rare and very precious.
00:03:38 --> 00:03:40 >> That doesn't mean that there is not life
00:03:40 --> 00:03:41 somewhere else in the universe. And it's
00:03:42 --> 00:03:43 what are the challenges with this? I I
00:03:43 --> 00:03:44 would like to think that we'll find the
00:03:44 --> 00:03:47 answer to that question in our lifetime.
00:03:47 --> 00:03:48 But the only way we'll get an answer to
00:03:48 --> 00:03:50 the question, are we alone within our
00:03:50 --> 00:03:52 lifetime is if that answer is no. If
00:03:52 --> 00:03:54 that answer is that there is life
00:03:54 --> 00:03:57 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.
00:04:01 --> 00:04:02 You know, when I was a kid, when you
00:04:02 --> 00:04:04 were a kid, one of the big questions was
00:04:04 --> 00:04:07 is the solar system unique or are there
00:04:07 --> 00:04:08 planets around other stars? And we'll
00:04:08 --> 00:04:10 talk about that more in the next
00:04:10 --> 00:04:13 episode. But there is nobody under the
00:04:13 --> 00:04:16 age of 30 31 alive on this planet that
00:04:16 --> 00:04:17 grew up in that shared universe with you
00:04:17 --> 00:04:19 and I. So that fundamental question got
00:04:19 --> 00:04:22 answered and answered in abundance and
00:04:22 --> 00:04:23 answering that question is the first
00:04:23 --> 00:04:26 real step to say is there life elsewhere
00:04:26 --> 00:04:28 beyond the solar system
00:04:28 --> 00:04:31 >> because in order to find life beyond the
00:04:31 --> 00:04:32 solar system we first need to know that
00:04:32 --> 00:04:35 there's somewhere that life could exist.
00:04:35 --> 00:04:36 The question of life in the solar system
00:04:36 --> 00:04:38 is a different one and that's all part
00:04:38 --> 00:04:39 of astrobiology. So if you bundle all of
00:04:40 --> 00:04:42 this together, that question of are we
00:04:42 --> 00:04:44 alone? Is there life elsewhere? Which
00:04:44 --> 00:04:46 brings with it questions like what is
00:04:46 --> 00:04:48 the origin of life? Why are we here? How
00:04:48 --> 00:04:49 did life begin? How did it get
00:04:50 --> 00:04:51 established? What are the processes
00:04:51 --> 00:04:53 needed? Everything like that.
00:04:53 --> 00:04:53 >> Yeah.
00:04:53 --> 00:04:55 >> Is what gets bundled in in astrobiology.
00:04:55 --> 00:04:58 And astrobiology is a very very weird
00:04:58 --> 00:05:00 science. I know certainly early in my
00:05:00 --> 00:05:02 career a lot of older scientists viewed
00:05:02 --> 00:05:05 astrobiology in a similar way to the way
00:05:05 --> 00:05:07 a lot of astronomers view astrology
00:05:07 --> 00:05:08 almost. you know, they viewed it as
00:05:08 --> 00:05:10 being speculation, fiction, and hook,
00:05:10 --> 00:05:13 you know, total bogus, waste of time
00:05:13 --> 00:05:14 stuff,
00:05:14 --> 00:05:16 >> but it really isn't.
00:05:16 --> 00:05:18 >> Yeah. But one of the real challenges is
00:05:18 --> 00:05:20 uh it's not a question that one single
00:05:20 --> 00:05:22 discipline on its own can answer, right?
00:05:22 --> 00:05:24 It's not like in astronomy, you you're
00:05:24 --> 00:05:26 studying how stars form, so you talk to
00:05:26 --> 00:05:28 astronomers. In astrobiology, if we're
00:05:28 --> 00:05:32 looking at everything to do with life,
00:05:32 --> 00:05:34 astronomers like myself can't do it on
00:05:34 --> 00:05:36 their own. Biologists can't do it on
00:05:36 --> 00:05:38 their own. You need geoysicists, you
00:05:38 --> 00:05:41 need chemists, you need every area of
00:05:41 --> 00:05:43 human scientific endeavor to come
00:05:43 --> 00:05:45 together because as scientists, our
00:05:45 --> 00:05:47 knowledge is somewhat siloed. I think
00:05:47 --> 00:05:48 I've said in previous episodes, the
00:05:48 --> 00:05:50 further you go away from what your
00:05:50 --> 00:05:52 specialtity is, the more out of date and
00:05:52 --> 00:05:53 the more superficial your knowledge is.
00:05:53 --> 00:05:55 So I always view my knowledge as being
00:05:55 --> 00:05:57 almost like a Christmas tree shape. I've
00:05:57 --> 00:05:58 got a lot of knowledge about a very
00:05:58 --> 00:06:00 narrow area at the top and the further
00:06:00 --> 00:06:02 you go from that area, the less
00:06:02 --> 00:06:03 knowledge I have, but the broader my
00:06:04 --> 00:06:05 knowledge base gets. And I think every
00:06:05 --> 00:06:07 human's like that. And you can almost
00:06:08 --> 00:06:10 imagine that if you're trying to answer
00:06:10 --> 00:06:11 the question of what you need for life,
00:06:11 --> 00:06:13 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
00:06:18 --> 00:06:20 to 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
00:06:26 --> 00:06:28 that is needed that is outside your
00:06:28 --> 00:06:30 silo. And so that's where the
00:06:30 --> 00:06:33 interdicciplinary nature comes in. No
00:06:33 --> 00:06:35 one discipline can answer it their own.
00:06:35 --> 00:06:37 And that means astrobiology conferences
00:06:37 --> 00:06:39 tend to be mind-bogglingly bonkers and
00:06:40 --> 00:06:42 you get people from very different
00:06:42 --> 00:06:45 disciplines along. And you learn a lot
00:06:45 --> 00:06:47 that updates your knowledge from when
00:06:47 --> 00:06:48 you went to high school. You also learn
00:06:48 --> 00:06:51 a lot that isn't about the science but
00:06:51 --> 00:06:54 is about the scientists. And it's really
00:06:54 --> 00:06:55 interesting because we all think we're
00:06:55 --> 00:06:56 individuals. It's like that Montipython
00:06:56 --> 00:06:57 thing, isn't it? We're all individuals
00:06:57 --> 00:06:59 and there's a voice at the back that
00:06:59 --> 00:06:59 goes, "I'm not.
00:06:59 --> 00:07:00 >> I'm not."
00:07:00 --> 00:07:02 >> Yeah. It's a bit like that. We're we all
00:07:02 --> 00:07:04 think we're all individuals and we're
00:07:04 --> 00:07:05 very unique in the way we think and the
00:07:05 --> 00:07:07 way we present. But when you go to one
00:07:07 --> 00:07:08 of these conferences that's so
00:07:08 --> 00:07:10 multiddisciplinary,
00:07:10 --> 00:07:12 the different disciplines present in
00:07:12 --> 00:07:13 different ways to one another. But
00:07:13 --> 00:07:14 within the discipline, there are
00:07:14 --> 00:07:16 similarities, you know. So if you see
00:07:16 --> 00:07:18 the talks I give, I have beautiful
00:07:18 --> 00:07:20 pictures and bright text, white or
00:07:20 --> 00:07:22 yellow on them, limited text, usually a
00:07:22 --> 00:07:24 dark background. And that's really
00:07:24 --> 00:07:26 common for astronomers. You go to a talk
00:07:26 --> 00:07:30 by a kind of plate tectonics person and
00:07:30 --> 00:07:31 suddenly you've got this mish mash of
00:07:31 --> 00:07:34 colors on a totally different background
00:07:34 --> 00:07:36 where there's a bit more text but the
00:07:36 --> 00:07:38 color schemes are a bit to me kind of
00:07:38 --> 00:07:39 psychedelic and like something you'd see
00:07:39 --> 00:07:42 out of a 1970s cartoon you know
00:07:42 --> 00:07:43 >> because they're used to working with
00:07:43 --> 00:07:46 these geological maps that um have a
00:07:46 --> 00:07:47 very different color palette and
00:07:47 --> 00:07:49 sensibility I think. And then you get
00:07:49 --> 00:07:50 talks from the biologists where they've
00:07:50 --> 00:07:53 got the name of one bacterium and it
00:07:53 --> 00:07:54 fills half of the page because it's such
00:07:54 --> 00:07:56 a lengthy scientific name and they've
00:07:56 --> 00:07:57 got loads of text.
00:07:57 --> 00:08:00 >> And so you learn a lot about how what
00:08:00 --> 00:08:02 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 trains you to problem solve
00:08:08 --> 00:08:10 because it trains you in a lot of
00:08:10 --> 00:08:11 different ways. essentially programs
00:08:11 --> 00:08:13 people and you know I find that side of
00:08:13 --> 00:08:15 things really fascinating because it's a
00:08:15 --> 00:08:17 good way to learn to improve your
00:08:17 --> 00:08:18 communication skills and you also pick
00:08:18 --> 00:08:22 up all this abundance of wow I never
00:08:22 --> 00:08:24 knew that you know and that's what we
00:08:24 --> 00:08:26 need if we are to answer questions like
00:08:26 --> 00:08:28 how did life begin where did life come
00:08:28 --> 00:08:30 from are we alone
00:08:30 --> 00:08:32 >> yeah and that's really an interesting
00:08:32 --> 00:08:35 question because uh it could be life not
00:08:35 --> 00:08:38 as we know it like we you know we're
00:08:38 --> 00:08:39 assuming carbon based life forms but
00:08:40 --> 00:08:42 there could be life forms that have been
00:08:42 --> 00:08:43 created out of a completely different
00:08:43 --> 00:08:46 soup mix. Uh two things I want to get
00:08:46 --> 00:08:48 out of the way quickly. The Drake
00:08:48 --> 00:08:51 equation which uh was created to try and
00:08:51 --> 00:08:54 assess how much intelligent life that
00:08:54 --> 00:08:56 was able to communicate existed in the
00:08:56 --> 00:08:58 universe and the answer is still one.
00:08:58 --> 00:09:01 And the Fermy paradox which says you
00:09:01 --> 00:09:04 know um that statistically there's a
00:09:04 --> 00:09:06 high probability of extraterrestrial
00:09:06 --> 00:09:10 life. So where is everybody? And that's
00:09:10 --> 00:09:12 what astrobiology is really, isn't it?
00:09:12 --> 00:09:15 Where is everybody? And and will they be
00:09:15 --> 00:09:19 people or will they be microbes? And I
00:09:19 --> 00:09:21 suppose my first question to you is uh
00:09:21 --> 00:09:23 you're talking about finding life
00:09:23 --> 00:09:25 outside the solar system. Aren't we
00:09:25 --> 00:09:28 likely to find it first within the solar
00:09:28 --> 00:09:29 system?
00:09:29 --> 00:09:31 >> So that's a really good question. I was
00:09:31 --> 00:09:32 going to talk about that a bit as well
00:09:32 --> 00:09:35 because I think there are two different
00:09:35 --> 00:09:37 places in a broad sense we're looking
00:09:37 --> 00:09:39 for life elsewhere. One is
00:09:39 --> 00:09:41 in the outer solar system or on Mars,
00:09:41 --> 00:09:43 you know, in our solar system on one of
00:09:43 --> 00:09:45 the planets or on the icy objects and
00:09:45 --> 00:09:48 the other is beyond the solar system.
00:09:48 --> 00:09:51 >> And those two things have very different
00:09:51 --> 00:09:53 characteristics.
00:09:53 --> 00:09:56 What I mean by that is that objects that
00:09:56 --> 00:09:57 are in our solar system are in our
00:09:57 --> 00:09:59 backyard. They're the only things in
00:09:59 --> 00:10:01 astronomy that we can get up close and
00:10:01 --> 00:10:03 personal with. So in the solar system,
00:10:03 --> 00:10:06 the search life elsewhere is being
00:10:06 --> 00:10:09 driven by robotic exploration in the
00:10:09 --> 00:10:11 main. Yes, there's a little bit of
00:10:11 --> 00:10:13 observation from Earth. We saw that with
00:10:13 --> 00:10:15 the phosphine story on Venus that I
00:10:15 --> 00:10:18 ranted about a little bit last week. Um
00:10:18 --> 00:10:19 and the wonderful caution shown by
00:10:19 --> 00:10:21 scientists that was not necessarily
00:10:21 --> 00:10:23 reflected in the coverage. Um but a lot
00:10:23 --> 00:10:27 of the search in the solar system is
00:10:27 --> 00:10:29 robotic in nature. We send spacecraft to
00:10:29 --> 00:10:31 places to study them up close and
00:10:31 --> 00:10:33 personal and we can't do that around
00:10:33 --> 00:10:35 other stars. Around other stars, it's
00:10:35 --> 00:10:37 very much a remote sensing type deal. So
00:10:37 --> 00:10:38 there are different ways of doing it.
00:10:38 --> 00:10:41 Now I think there is a realistic chance
00:10:41 --> 00:10:43 we'll find life elsewhere in the solar
00:10:43 --> 00:10:45 system. There's a lot of good reasons
00:10:45 --> 00:10:47 for that. Now, before I dive into that a
00:10:47 --> 00:10:49 little bit, I'll just take a step back
00:10:49 --> 00:10:50 and come back to that point you made
00:10:50 --> 00:10:52 about life like us and carbon based life
00:10:52 --> 00:10:54 versus other things because it's really
00:10:54 --> 00:10:55 important to make explicit what is
00:10:56 --> 00:10:59 normally an implicit bias when
00:10:59 --> 00:11:00 scientists are talking about
00:11:00 --> 00:11:01 astrobiology.
00:11:01 --> 00:11:03 Um, it's really made clear when you
00:11:03 --> 00:11:05 think about NASA and efforts on the moon
00:11:06 --> 00:11:08 where they have on on Mars, sorry, where
00:11:08 --> 00:11:09 they have aggressively said the strategy
00:11:09 --> 00:11:12 to look for life is to follow the water.
00:11:12 --> 00:11:13 M
00:11:13 --> 00:11:16 >> what they're doing there is making an
00:11:16 --> 00:11:17 implicit assumption that is an
00:11:18 --> 00:11:19 assumption that is not always written
00:11:19 --> 00:11:21 out and is clear but is at the back of
00:11:21 --> 00:11:24 it that life that we look for will be
00:11:24 --> 00:11:26 life like us and I mean life like earth
00:11:26 --> 00:11:29 life now we can imagine you see it on
00:11:29 --> 00:11:31 science fiction all the time you know
00:11:31 --> 00:11:32 life that is very other it might be
00:11:32 --> 00:11:34 molten metal monsters on a magma planet
00:11:34 --> 00:11:36 or it might be an intelligent hydrogen
00:11:36 --> 00:11:38 cloud that nevertheless wants to flirt
00:11:38 --> 00:11:41 with Captain Kirk it's very different
00:11:41 --> 00:11:43 kinds of life. But fundamentally, we
00:11:43 --> 00:11:46 only know of one type of life that does
00:11:46 --> 00:11:49 exist and that's life like earth life.
00:11:49 --> 00:11:52 And so when we look for life elsewhere,
00:11:52 --> 00:11:55 at least in what is the early stages
00:11:55 --> 00:11:57 still, it is really important to look
00:11:57 --> 00:11:59 for something that we know can exist and
00:11:59 --> 00:12:01 does exist rather than looking for
00:12:01 --> 00:12:03 things that we could speculate might
00:12:03 --> 00:12:05 exist. If you've got to focus your
00:12:05 --> 00:12:08 efforts with limited resources, it makes
00:12:08 --> 00:12:10 sense to follow the kind of welltrodden
00:12:10 --> 00:12:12 footsteps of what we know about life on
00:12:12 --> 00:12:14 Earth. And from an astronomer's point of
00:12:14 --> 00:12:16 view, life on Earth needs three things.
00:12:16 --> 00:12:18 You know, it needs liquid water, it
00:12:18 --> 00:12:20 needs a source of energy and a source of
00:12:20 --> 00:12:22 nutrients. And quite often those two are
00:12:22 --> 00:12:24 the same thing, but not always. And
00:12:24 --> 00:12:26 wherever we find those things on Earth,
00:12:26 --> 00:12:28 we find life in abundance. And once life
00:12:28 --> 00:12:29 gets there, it's really hard to get rid
00:12:29 --> 00:12:31 of. You know, anybody who's had ants
00:12:31 --> 00:12:33 getting into their kitchen or the mice
00:12:33 --> 00:12:35 plague that we talked about last week
00:12:35 --> 00:12:38 knows just how life once it gets
00:12:38 --> 00:12:41 established keeps going. And so it makes
00:12:41 --> 00:12:43 sense. And a lot of what I'll talk about
00:12:43 --> 00:12:45 for all the rest of the episode is kind
00:12:45 --> 00:12:47 of based on this assumption that we're
00:12:47 --> 00:12:49 looking at at least initially for life
00:12:50 --> 00:12:52 like us that has the same needs as us
00:12:52 --> 00:12:54 where the us is the broad the entire
00:12:54 --> 00:12:56 panel play of life on Earth rather than
00:12:56 --> 00:12:58 us as in me and the having this chat
00:12:58 --> 00:13:01 back and forward. What that leads to
00:13:01 --> 00:13:03 though is a lot of studies that have
00:13:03 --> 00:13:04 been done for the solar system are very
00:13:04 --> 00:13:07 waterdriven. And if you go back decades,
00:13:07 --> 00:13:09 you could go back to the late 1800s when
00:13:10 --> 00:13:11 people were obsessed with this idea that
00:13:11 --> 00:13:13 there was an advanced technological
00:13:13 --> 00:13:15 civilization on Mars that was running
00:13:15 --> 00:13:17 out of time because the planet was
00:13:17 --> 00:13:19 desolate and barren. And this was all
00:13:19 --> 00:13:21 motivated by the observations of the
00:13:21 --> 00:13:23 canali, the channels on Mars that don't
00:13:24 --> 00:13:26 exist, which were mistransated as
00:13:26 --> 00:13:27 canals. And canals on Earth are a very
00:13:28 --> 00:13:30 clear sign of human activity.
00:13:30 --> 00:13:32 >> Yeah. People at that time were so
00:13:32 --> 00:13:34 certain that we'd already found life
00:13:34 --> 00:13:37 that when there was a prize awarded um a
00:13:37 --> 00:13:39 prize laid out sorry and announced I
00:13:39 --> 00:13:41 think it was like in 1899 or something
00:13:41 --> 00:13:43 for the search for life for the first
00:13:43 --> 00:13:45 person to discover life elsewhere to
00:13:45 --> 00:13:47 find evidence of life elsewhere. That
00:13:47 --> 00:13:50 prize explicitly excluded Mars because
00:13:50 --> 00:13:51 it was felt that life on Mars was so
00:13:51 --> 00:13:53 well established that that was a
00:13:53 --> 00:13:55 no-brainer. You know, it was such a
00:13:55 --> 00:13:56 thing in popular culture that when the
00:13:56 --> 00:13:58 War of the Worlds broadcast happened in
00:13:58 --> 00:14:00 the 1930s, people thought it was live
00:14:00 --> 00:14:02 news coverage and panicked.
00:14:02 --> 00:14:02 >> Yes. You know,
00:14:02 --> 00:14:05 >> the night that panicked America.
00:14:05 --> 00:14:08 >> Yeah. And there's this whole heritage of
00:14:08 --> 00:14:11 our expectation of life being common and
00:14:11 --> 00:14:14 it being life like us requiring water.
00:14:14 --> 00:14:16 When we went to Mars, like in the 1960s
00:14:16 --> 00:14:19 with spacecraft, Mars was shown to be
00:14:19 --> 00:14:21 the desolate arid world we knew today.
00:14:21 --> 00:14:23 That put to an end the thoughts of an
00:14:23 --> 00:14:25 advanced civilization there. And from
00:14:25 --> 00:14:27 that time onwards there was a period
00:14:27 --> 00:14:29 where arguments in astrobiology fell
00:14:29 --> 00:14:31 very much out of favor, out of fashion.
00:14:31 --> 00:14:32 And it was kind of viewed much more
00:14:32 --> 00:14:34 likely that life was almost unique. We
00:14:34 --> 00:14:36 were alone. There was no way you could
00:14:36 --> 00:14:38 look. And there's this argument that I
00:14:38 --> 00:14:41 often hear as that water is scarce in
00:14:41 --> 00:14:44 the universe. And that makes my head
00:14:44 --> 00:14:45 hurt. I think this is one of those big
00:14:45 --> 00:14:49 myths that is a myth of miscommunication
00:14:49 --> 00:14:51 or a myth of
00:14:51 --> 00:14:55 language being a personal thing. What I
00:14:55 --> 00:14:57 mean by that is and I I'm always try to
00:14:57 --> 00:14:59 be very aware of this when I'm as a
00:14:59 --> 00:15:02 communicator that words have different
00:15:02 --> 00:15:05 meanings to different people. And so the
00:15:05 --> 00:15:07 same word that I say you'll hear and it
00:15:08 --> 00:15:09 doesn't always mean the same thing to
00:15:09 --> 00:15:10 you or me. One of one of the best
00:15:10 --> 00:15:13 examples of this is when you get people
00:15:13 --> 00:15:15 who are trying to argue against an area
00:15:16 --> 00:15:17 of science, maybe vaccines, maybe
00:15:17 --> 00:15:19 climate change, maybe something less
00:15:19 --> 00:15:21 controversial. You'll often hear people
00:15:21 --> 00:15:23 say that, well, climate change is just a
00:15:23 --> 00:15:25 theory, or vaccines are just a theory,
00:15:25 --> 00:15:27 or the Big Bang is just a theory. And to
00:15:27 --> 00:15:31 a lot of people, a theory just means a
00:15:31 --> 00:15:34 loose idea. A lot of people will say,
00:15:34 --> 00:15:36 "Why isn't your car starting this
00:15:36 --> 00:15:38 morning?" Well, I've got a theory. To a
00:15:38 --> 00:15:40 scientist, a theory is a very different
00:15:40 --> 00:15:42 beast and it's tied to the ability to
00:15:42 --> 00:15:45 make testable predictions and repeated
00:15:45 --> 00:15:47 testing. There's a lot of philosophy of
00:15:47 --> 00:15:49 science. I did a philosophy of physics
00:15:50 --> 00:15:51 course at university when I was 18 and I
00:15:51 --> 00:15:52 wish I'd done it when I was at the end
00:15:52 --> 00:15:54 of my degree, not the start cuz I'd have
00:15:54 --> 00:15:56 got a lot more out of it. But there are
00:15:56 --> 00:15:58 people who have aggressively studied the
00:15:58 --> 00:16:01 philosophy of the scientific method. And
00:16:01 --> 00:16:03 even that philosophy varies a little bit
00:16:03 --> 00:16:05 discipline to discipline. A lot of other
00:16:05 --> 00:16:06 disciplines that are the experimental
00:16:06 --> 00:16:08 ones are are very much more hypothesis
00:16:08 --> 00:16:11 driven than astronomy where we say I'm
00:16:11 --> 00:16:12 interested in what this is. Let's have a
00:16:12 --> 00:16:14 look. There's not really a hypothesis. I
00:16:14 --> 00:16:15 just want to look at it and find out. At
00:16:15 --> 00:16:18 least that's how I work. But you also
00:16:18 --> 00:16:20 have this thing where at least from my
00:16:20 --> 00:16:21 philosophy, you can never prove a
00:16:22 --> 00:16:24 theory, but you can disprove a theory.
00:16:24 --> 00:16:26 What I mean by that is if you test a
00:16:26 --> 00:16:29 theory a million times and each time
00:16:29 --> 00:16:31 it's backed it up, you haven't proven
00:16:31 --> 00:16:32 that theory. You've just shown that
00:16:32 --> 00:16:34 theory is a very good approximation to
00:16:34 --> 00:16:36 what's actually happening. So take the
00:16:36 --> 00:16:38 example of me flipping a coin. I can
00:16:38 --> 00:16:40 have a theory that says coins will
00:16:40 --> 00:16:43 always land heads or tails. Test that a
00:16:43 --> 00:16:44 million times and odds are a million
00:16:44 --> 00:16:46 times you'll land heads or tails. But
00:16:46 --> 00:16:48 you've not proven that theory. You've
00:16:48 --> 00:16:49 just said it's a very close
00:16:49 --> 00:16:51 approximation to the truth. You could
00:16:51 --> 00:16:52 toss them 10 million times and one time
00:16:52 --> 00:16:54 your coin lands on its edge and
00:16:54 --> 00:16:54 balances.
00:16:54 --> 00:16:55 >> Yeah.
00:16:55 --> 00:16:56 >> That one observation. And so as long as
00:16:56 --> 00:16:58 it's well documented and is repeatable
00:16:58 --> 00:17:00 is enough to kill that theory and then
00:17:00 --> 00:17:01 you need to develop something more
00:17:01 --> 00:17:03 complex. You know
00:17:03 --> 00:17:05 >> that's where it goes from. Now that's a
00:17:05 --> 00:17:07 very roundabout way of coming back at
00:17:07 --> 00:17:11 this water being scarce myth. I think
00:17:11 --> 00:17:13 where that comes from is when you talk
00:17:13 --> 00:17:17 to me about water I am just thinking
00:17:17 --> 00:17:19 about the molecule. I'm not thinking
00:17:19 --> 00:17:22 about the physical state. So to me water
00:17:22 --> 00:17:24 can be water ice. It can be liquid
00:17:24 --> 00:17:26 water. It can be water vapor. But to
00:17:26 --> 00:17:28 most people, if you say water, they
00:17:28 --> 00:17:30 visualize liquid water. Yeah.
00:17:30 --> 00:17:31 >> Right. If if I say, "Would you like some
00:17:31 --> 00:17:33 water?" You're not expecting me to
00:17:33 --> 00:17:35 immediately start steing your face.
00:17:35 --> 00:17:36 You're expecting a glass of water.
00:17:36 --> 00:17:38 Right?
00:17:38 --> 00:17:40 What that means is that when people look
00:17:40 --> 00:17:41 out at the solar system and look
00:17:41 --> 00:17:43 everywhere else, we see this thing that
00:17:43 --> 00:17:45 Earth is the only place where we have
00:17:45 --> 00:17:47 abundant liquid water all the time on
00:17:47 --> 00:17:50 the surface. And so people have this
00:17:50 --> 00:17:51 idea that water is scarce where what
00:17:51 --> 00:17:54 they're really thinking is liquid water
00:17:54 --> 00:17:58 on the surface of an object is scarce.
00:17:58 --> 00:18:00 >> But that drove a lot of this idea that
00:18:00 --> 00:18:02 life will be scarce because life needs
00:18:02 --> 00:18:04 liquid water on Earth. The Earth's the
00:18:04 --> 00:18:06 only place with liquid water. Ergo life
00:18:06 --> 00:18:09 will be scarce. That's moved on though
00:18:09 --> 00:18:10 in about the last three or four decades.
00:18:10 --> 00:18:12 partially with the exploration of Mars
00:18:12 --> 00:18:15 where we're getting an overwhelmingly
00:18:15 --> 00:18:17 greater amount of evidence that Mars in
00:18:17 --> 00:18:19 the past was warm and wet, that it had
00:18:19 --> 00:18:20 oceans and lakes. They may have been
00:18:20 --> 00:18:22 slushy or they may have been properly
00:18:22 --> 00:18:24 liquid, but it had oceans and lakes for
00:18:24 --> 00:18:26 a long time of liquid water. And we've
00:18:26 --> 00:18:27 even got evidence that there is
00:18:27 --> 00:18:29 permanent liquid water on Mars as we're
00:18:29 --> 00:18:30 talking now in the form of liquid water
00:18:30 --> 00:18:33 in the Martian polar ice caps and you
00:18:33 --> 00:18:34 get temporal liquid water running on the
00:18:34 --> 00:18:36 surface. The other thing we found in the
00:18:36 --> 00:18:39 solar system is liquid water in
00:18:39 --> 00:18:41 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
00:18:47 --> 00:18:48 the dwarf planet Pluto or inside the
00:18:48 --> 00:18:50 dwarf planet Pluto probably in the
00:18:50 --> 00:18:53 larger edge kipeld objects transepun
00:18:53 --> 00:18:56 objects maybe in other places as well
00:18:56 --> 00:18:58 even in places as small as Enceladus so
00:18:58 --> 00:19:01 there's been this revolution from the
00:19:01 --> 00:19:02 point of view of the solar system
00:19:02 --> 00:19:04 through my lifetime that actually liquid
00:19:04 --> 00:19:06 water isn't scarce.
00:19:06 --> 00:19:08 >> 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
00:19:12 --> 00:19:13 again that the solar system is a good
00:19:13 --> 00:19:15 place to look for life and that's
00:19:15 --> 00:19:17 driving a lot of exploration missions
00:19:17 --> 00:19:19 all the Mars exploration past and future
00:19:20 --> 00:19:22 focused around that idea. the fact that
00:19:22 --> 00:19:23 we've got two missions going to the
00:19:23 --> 00:19:25 Jovian ICE satellites at the minute
00:19:25 --> 00:19:27 juice um the Jupyter moons explorer and
00:19:27 --> 00:19:29 the Europa Clipper which are to
00:19:29 --> 00:19:31 characterize those moons better to
00:19:31 --> 00:19:33 prepare for potential future landings in
00:19:33 --> 00:19:35 the 2040s or 50s to get through the ice
00:19:35 --> 00:19:37 and look at what's underneath. We've got
00:19:37 --> 00:19:39 the Dragonfly mission going out to
00:19:39 --> 00:19:41 Titan, launching in a couple of years
00:19:41 --> 00:19:43 time, probably next year. Hoping to get
00:19:43 --> 00:19:46 there 2034 that will land on the only
00:19:46 --> 00:19:47 other place that has liquid on its
00:19:47 --> 00:19:50 surface exposed to the atmosphere in the
00:19:50 --> 00:19:51 solar system and that's Titan with lakes
00:19:51 --> 00:19:53 of liquid methane and ethane. The water
00:19:54 --> 00:19:55 there is harder than granite and makes
00:19:55 --> 00:19:57 up the mountains. But there's this huge
00:19:57 --> 00:19:59 effort to explore our solar system and
00:19:59 --> 00:20:01 actually go there and look, which we
00:20:01 --> 00:20:03 can't do when we're looking at planets
00:20:03 --> 00:20:05 around the stars. And by going there and
00:20:05 --> 00:20:08 looking if there is anything there past
00:20:08 --> 00:20:10 or present eventually we'll find it.
00:20:10 --> 00:20:13 >> Now that immediately then poses a really
00:20:13 --> 00:20:14 fascinating one. So if we find life on
00:20:14 --> 00:20:18 Mars or we find life on Europa
00:20:18 --> 00:20:21 if we can look at that life and figure
00:20:21 --> 00:20:24 out its heritage figure out its DNA and
00:20:24 --> 00:20:26 I'm not a biologist so I'll be a little
00:20:26 --> 00:20:29 woolly on that. It will be very quick
00:20:29 --> 00:20:31 and very apparent whether that life has
00:20:31 --> 00:20:32 a shared origin to life on earth or
00:20:32 --> 00:20:34 whether it has a separate origin to life
00:20:34 --> 00:20:36 on earth. Now the separate origin would
00:20:36 --> 00:20:38 mean that life got started
00:20:38 --> 00:20:40 simultaneously
00:20:40 --> 00:20:42 on two objects in the same planetary
00:20:42 --> 00:20:45 system in an icy backwater of a fairly
00:20:45 --> 00:20:48 unremarkable galaxy. If it got started
00:20:48 --> 00:20:49 two places side by side, surely that
00:20:49 --> 00:20:51 means life gets started more easily than
00:20:52 --> 00:20:54 we expect. Therefore, life should be
00:20:54 --> 00:20:56 common in the universe. That would be an
00:20:56 --> 00:20:59 obvious logical continuation. The other
00:20:59 --> 00:21:00 option is that we find life elsewhere in
00:21:00 --> 00:21:02 the solar system and it has a shared
00:21:02 --> 00:21:03 heritage life on Earth. What that means
00:21:04 --> 00:21:06 is that we analyze its makeup, we find
00:21:06 --> 00:21:09 that it has DNA like Earth DNA that has
00:21:09 --> 00:21:11 a shared universal common ancestor. And
00:21:11 --> 00:21:13 what that suggests is that once life
00:21:13 --> 00:21:14 gets started somewhere, it's
00:21:14 --> 00:21:16 transmissible. You know, you've got that
00:21:16 --> 00:21:18 old thing of don't go near Earth. It's
00:21:18 --> 00:21:20 got humans. They're contagious.
00:21:20 --> 00:21:22 This is the same kind of idea. If we
00:21:22 --> 00:21:24 find life on Mars and that life has a
00:21:24 --> 00:21:27 shared heritage with life on Earth, that
00:21:27 --> 00:21:29 validates strongly supports the idea of
00:21:29 --> 00:21:31 panspermia, which I've had a student
00:21:32 --> 00:21:35 just 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
00:21:42 --> 00:21:45 simple single origin and maybe even
00:21:45 --> 00:21:46 Earth wasn't that origin, you know,
00:21:46 --> 00:21:48 maybe we're Martians, maybe we're
00:21:48 --> 00:21:51 Venucians or Venerians. I think that
00:21:51 --> 00:21:52 Venerian used to be the adjective for
00:21:52 --> 00:21:54 Ven adjective the right word used to be
00:21:54 --> 00:21:55 the word for Venus in the way that
00:21:55 --> 00:21:57 Martian was for Mars but it was a bit
00:21:57 --> 00:22:01 too close to venerial 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 venerial creatures um we don't
00:22:05 --> 00:22:07 know but what that suggests is that if
00:22:07 --> 00:22:09 life is transferred easily and
00:22:09 --> 00:22:11 effectively once it originates life
00:22:11 --> 00:22:14 could be common in the universe so to me
00:22:14 --> 00:22:15 finding life in the solar system would
00:22:15 --> 00:22:17 be awesome I think it's eminently
00:22:17 --> 00:22:19 feasible and either way it will shed new
00:22:20 --> 00:22:22 on the commonality of life beyond the
00:22:22 --> 00:22:24 solar system. We will be looking for
00:22:24 --> 00:22:27 life like us. It is possible to imagine
00:22:27 --> 00:22:28 life that is not like us that has
00:22:28 --> 00:22:29 different requirements but that will
00:22:29 --> 00:22:32 probably be a bit harder to find and we
00:22:32 --> 00:22:35 don't know what it would be. Whereas
00:22:35 --> 00:22:36 with life like us, we know things to
00:22:36 --> 00:22:38 look for. So that makes it a bit easier
00:22:38 --> 00:22:41 for us to look for life like us. It also
00:22:41 --> 00:22:44 makes it, I'd say, a little bit stronger
00:22:44 --> 00:22:46 as a case when you're asking for funding
00:22:46 --> 00:22:48 because you can say, well, we already
00:22:48 --> 00:22:50 know this kind of life can exist. So,
00:22:50 --> 00:22:51 we're going to look at a place where the
00:22:51 --> 00:22:52 conditions are similar to where we know
00:22:52 --> 00:22:54 it does exist and see if we find it
00:22:54 --> 00:22:56 there as well.
00:22:56 --> 00:22:58 >> Okay, let's take a short break. Uh, this
00:22:58 --> 00:23:01 is Space Nuts with Andrew Dunley and
00:23:01 --> 00:23:04 Professor Jonty Horner.
00:23:04 --> 00:23:06 Let's take a short break from the show
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00:24:53 --> 00:24:57 >> I'm going to step off the mount.
00:24:57 --> 00:25:02 That's one small step for man,
00:25:02 --> 00:25:05 one leap for mankind.
00:25:05 --> 00:25:07 >> Space nuts.
00:25:07 --> 00:25:09 >> It's not Professor Fred Watson at the
00:25:09 --> 00:25:10 moment. He's away. We've got Professor
00:25:10 --> 00:25:12 Jonty Hoer and we're talking
00:25:12 --> 00:25:15 astrobiology in this uh little special
00:25:15 --> 00:25:18 edition. Um, one thing I heard in the
00:25:18 --> 00:25:19 news recently, I think Fred and I talked
00:25:20 --> 00:25:21 about it was uh, you know, we've been
00:25:21 --> 00:25:23 talking about water and if you want to
00:25:23 --> 00:25:25 find the people, find the water, that
00:25:25 --> 00:25:27 sort of thing. But there was one
00:25:27 --> 00:25:29 particular study that uh was recently
00:25:30 --> 00:25:31 released that says if you want to find
00:25:31 --> 00:25:34 the people, find the coal. What do you
00:25:34 --> 00:25:35 think of that theory?
00:25:35 --> 00:25:37 >> That's an interesting one. So that's the
00:25:37 --> 00:25:39 idea that if you want to find somebody
00:25:39 --> 00:25:40 to talk to,
00:25:40 --> 00:25:42 >> there needs to be something to fuel an
00:25:42 --> 00:25:44 industrial revolution. And again, this
00:25:44 --> 00:25:45 is
00:25:45 --> 00:25:46 >> I think science fiction sometimes does
00:25:46 --> 00:25:48 this really ask this really interesting
00:25:48 --> 00:25:50 questions of
00:25:50 --> 00:25:53 >> almost is the path that we have followed
00:25:54 --> 00:25:55 the one that everyone will follow? you
00:25:55 --> 00:25:57 know because there's so much to some
00:25:57 --> 00:25:59 degree randomness in the things that
00:25:59 --> 00:26:02 have driven our knowledge and our
00:26:02 --> 00:26:04 development of things you know um
00:26:04 --> 00:26:06 obviously a good example is a famous
00:26:06 --> 00:26:08 myth about penicellin that if um you
00:26:08 --> 00:26:10 leave your bread out and it goes moldy
00:26:10 --> 00:26:13 that makes your pus more effective um
00:26:13 --> 00:26:15 and that was an incredible scientific
00:26:15 --> 00:26:17 re revolution driven by that discovery
00:26:17 --> 00:26:19 there
00:26:19 --> 00:26:21 who's to say other civilizations would
00:26:21 --> 00:26:22 have the same discoveries in the same
00:26:22 --> 00:26:26 order now to advance. We have required
00:26:26 --> 00:26:29 advances in energy in order to allow us
00:26:29 --> 00:26:32 to better develop technology and develop
00:26:32 --> 00:26:34 the things that everything's made of.
00:26:34 --> 00:26:36 You know, if we didn't have anything
00:26:36 --> 00:26:38 that you could burn, it would be very
00:26:38 --> 00:26:40 very challenging to smelt metal. If you
00:26:40 --> 00:26:42 couldn't smelt metal, how do you build
00:26:42 --> 00:26:43 electronics?
00:26:43 --> 00:26:45 >> You are spot on. That's exactly what the
00:26:45 --> 00:26:48 article was all about. And uh the bottom
00:26:48 --> 00:26:51 line was uh that because of the timing
00:26:51 --> 00:26:55 required, it lessens the likelihood of
00:26:55 --> 00:26:59 us finding uh people like us. It reduces
00:26:59 --> 00:27:00 the odds.
00:27:00 --> 00:27:02 >> And this is where there's a difference
00:27:02 --> 00:27:04 between the search for extraterrestrial
00:27:04 --> 00:27:06 intelligence and the search for life. So
00:27:06 --> 00:27:07 the search for extraterrestrial
00:27:07 --> 00:27:09 intelligence is like a subset of the
00:27:09 --> 00:27:12 search for life. Search for life is a
00:27:12 --> 00:27:14 search for bacteria as much as it's the
00:27:14 --> 00:27:17 search for communicative aliens. And
00:27:17 --> 00:27:19 there's been a lot of stuff written and
00:27:19 --> 00:27:22 discussed about whether evolutionary
00:27:22 --> 00:27:24 quirks have benefited us by being here,
00:27:24 --> 00:27:26 you know, in terms of we're a social
00:27:26 --> 00:27:27 communal animal that shares resources
00:27:27 --> 00:27:30 and shares learning. There have been
00:27:30 --> 00:27:31 other ones like that from Aunt Collins.
00:27:31 --> 00:27:34 And I'm listening to a very chill and
00:27:34 --> 00:27:38 very silly um lit RPG. I think would be
00:27:38 --> 00:27:39 the description of the genre book called
00:27:39 --> 00:27:41 series of books called Chrysis at the
00:27:41 --> 00:27:44 minute where a young boy who dies for
00:27:44 --> 00:27:47 reasons is reincarnated in the b body of
00:27:47 --> 00:27:50 an ant. And it's a book about him as an
00:27:50 --> 00:27:52 ant and his life in the colony and stuff
00:27:52 --> 00:27:55 and it's bonkers but um you've got an
00:27:55 --> 00:27:57 advanced social species there and he
00:27:57 --> 00:27:59 finds ways without too many spoilers of
00:27:59 --> 00:28:00 giving them intelligence and what
00:28:00 --> 00:28:01 happens afterwards.
00:28:01 --> 00:28:03 >> There's a few species in the history of
00:28:03 --> 00:28:05 earth that have that kind of communal
00:28:05 --> 00:28:07 sharing of information thing. we're the
00:28:07 --> 00:28:09 only ones that have achieved what we've
00:28:09 --> 00:28:11 achieved. Some arguments are that's down
00:28:11 --> 00:28:13 to the development of language and our
00:28:13 --> 00:28:16 ability to produce complex language and
00:28:16 --> 00:28:17 also the opposable thumb being quite
00:28:17 --> 00:28:20 important. So there's a lot of stuff
00:28:20 --> 00:28:22 that there are many steps between the
00:28:22 --> 00:28:24 development of life and the development
00:28:24 --> 00:28:26 of intelligence and the development of
00:28:26 --> 00:28:28 intelligence itself doesn't necessarily
00:28:28 --> 00:28:29 mean the development of technological
00:28:30 --> 00:28:31 intelligence. You know, a lot of
00:28:31 --> 00:28:33 discussions about all the things octopi
00:28:33 --> 00:28:36 or octopods or octopidles octopi could
00:28:36 --> 00:28:38 achieve if they lived for more than 3
00:28:38 --> 00:28:41 years and if they were a social animal.
00:28:41 --> 00:28:42 They've got incredible brains. We're
00:28:42 --> 00:28:44 learning more and more about some of the
00:28:44 --> 00:28:47 brain power that birds exhibit.
00:28:47 --> 00:28:48 But none of them have become
00:28:48 --> 00:28:50 technological intelligences. And the
00:28:50 --> 00:28:52 search for extraterrestrial intelligence
00:28:52 --> 00:28:55 is very much centered around a
00:28:55 --> 00:28:58 technology that allows civilizations to
00:28:58 --> 00:29:00 communicate with one another. that
00:29:00 --> 00:29:02 therefore is based on many prerequisites
00:29:02 --> 00:29:03 that lead to the development of the
00:29:03 --> 00:29:05 ability to broadcast your existence to
00:29:05 --> 00:29:07 the cosmos. The coal thing's
00:29:07 --> 00:29:09 interesting. I mean, I'm not
00:29:09 --> 00:29:13 sufficiently archaeologically minded to
00:29:13 --> 00:29:16 be able to say with certainty that
00:29:16 --> 00:29:18 without coal, we wouldn't have got here.
00:29:18 --> 00:29:19 And the reason that I express caution on
00:29:19 --> 00:29:22 that coal and oil is that we have things
00:29:22 --> 00:29:24 that people burn for energy that are not
00:29:24 --> 00:29:26 coal and oil. M
00:29:26 --> 00:29:28 >> and I think a lot of the smelting that
00:29:28 --> 00:29:29 was done, and I may be wrong on this
00:29:29 --> 00:29:30 because I'm not an archaeologist. I just
00:29:30 --> 00:29:32 pick bits up when my partner's watching
00:29:32 --> 00:29:34 time team and things like that. She
00:29:34 --> 00:29:36 loves her archaeology, so I get a little
00:29:36 --> 00:29:38 bit of that as a very thin veneer. But I
00:29:38 --> 00:29:39 think a lot of the times when people
00:29:39 --> 00:29:41 smelted metals, talking about bronze and
00:29:41 --> 00:29:43 iron, they used wood or they use
00:29:44 --> 00:29:45 charcoal, which is a byproduct of
00:29:45 --> 00:29:46 burning wood.
00:29:46 --> 00:29:47 >> Yeah.
00:29:47 --> 00:29:50 So maybe it would be more challenging
00:29:50 --> 00:29:53 without the easy available energy of
00:29:53 --> 00:29:55 fossil fuels, without the easy available
00:29:55 --> 00:29:58 energy of coal, oil, gas. But it might
00:29:58 --> 00:29:59 be that that wouldn't be an
00:29:59 --> 00:30:00 insurmountable hurdle, but it would
00:30:00 --> 00:30:01 result in a different path being
00:30:01 --> 00:30:04 followed. You know, what would we get in
00:30:04 --> 00:30:06 terms of seam power if we were using
00:30:06 --> 00:30:08 wood and if we were using charcoal
00:30:08 --> 00:30:11 rather than other things? Would it lead
00:30:11 --> 00:30:13 to an earlier adoption of renewable
00:30:13 --> 00:30:15 energy in the form of wind power which
00:30:15 --> 00:30:17 was actually being used for hundreds of
00:30:17 --> 00:30:18 years? You go back to Europe and you see
00:30:18 --> 00:30:20 the windmills people use
00:30:20 --> 00:30:22 >> and watermills people's use.
00:30:22 --> 00:30:26 >> So I I don't know whether
00:30:26 --> 00:30:28 and this is a problem with all of
00:30:28 --> 00:30:30 astrobiology and it's a problem with a
00:30:30 --> 00:30:31 lot of the stuff that I'll talk about
00:30:31 --> 00:30:33 later about what makes a planet more
00:30:33 --> 00:30:35 suitable or less suitable. People have
00:30:35 --> 00:30:37 this tendency to find something that is
00:30:37 --> 00:30:40 unusual about us and there's a lot
00:30:40 --> 00:30:41 that's unusual about us. I mean there's
00:30:41 --> 00:30:42 a lot that's unusual about me and I hold
00:30:42 --> 00:30:45 my hand up about that. But they find
00:30:45 --> 00:30:47 things that are unusual
00:30:47 --> 00:30:49 and they say we are as far as we know
00:30:49 --> 00:30:50 unique in the cosmos. We are a
00:30:50 --> 00:30:51 technologically advanced civilization
00:30:52 --> 00:30:54 able to have this discussion.
00:30:54 --> 00:30:56 There has to be a reason that we're
00:30:56 --> 00:30:59 here. Everything that is unusual quite
00:30:59 --> 00:31:01 often gets held up as could this be the
00:31:01 --> 00:31:03 switch? If you didn't have this, we
00:31:04 --> 00:31:06 would not be here. And I tend to view
00:31:06 --> 00:31:08 them not as an on-off switch, but as a
00:31:08 --> 00:31:10 slider. They're like, and again, a
00:31:10 --> 00:31:12 gaming analogy would be varying the
00:31:12 --> 00:31:14 difficulty on your game. Some games,
00:31:14 --> 00:31:16 it's very kind of onoff, hard mode, easy
00:31:16 --> 00:31:18 mode. Others, particularly some of the
00:31:18 --> 00:31:20 role playing type games people play,
00:31:20 --> 00:31:22 have sliders for everything. And so, you
00:31:22 --> 00:31:26 can change things to the nth degree to
00:31:26 --> 00:31:28 tweak the challenge level. And I think
00:31:28 --> 00:31:30 all of these things like the existence
00:31:30 --> 00:31:34 of coal that get proposed as being a
00:31:34 --> 00:31:36 boundary, as being something that would
00:31:36 --> 00:31:38 be a block if you didn't have it, are
00:31:38 --> 00:31:39 actually probably more like one of those
00:31:39 --> 00:31:40 sliders. They're things that can
00:31:40 --> 00:31:42 facilitate,
00:31:42 --> 00:31:44 but it's really interesting to discuss
00:31:44 --> 00:31:45 them because we don't know how big a
00:31:46 --> 00:31:47 filter they are. We don't know how big a
00:31:48 --> 00:31:50 hurdle they are without digging into it
00:31:50 --> 00:31:51 more. And the more we can suggest these
00:31:51 --> 00:31:53 things, the more we can narrow them
00:31:53 --> 00:31:55 down. Ultimately, the only way we can
00:31:55 --> 00:31:57 finally test them is when we get a
00:31:57 --> 00:31:59 response to us, when we find
00:31:59 --> 00:32:02 technologically advanced life and then
00:32:02 --> 00:32:04 we learn about their heritage. What path
00:32:04 --> 00:32:07 did they follow? Did they invent fire
00:32:07 --> 00:32:10 before the wheel? Did they invent modern
00:32:10 --> 00:32:13 medicine before fire? And I've seen
00:32:14 --> 00:32:17 there's a fabulous famous old thread, I
00:32:17 --> 00:32:18 don't know, it wasn't from Reddit, it
00:32:18 --> 00:32:20 predates Reddit, but from one of the old
00:32:20 --> 00:32:24 messaging boards that talks about humans
00:32:24 --> 00:32:27 as the horror movie monsters of the
00:32:27 --> 00:32:29 universe. Because we always in science
00:32:29 --> 00:32:31 fiction, all the monsters we face, all
00:32:31 --> 00:32:33 the aliens we face are usually more
00:32:33 --> 00:32:35 something than us. And we overcome
00:32:35 --> 00:32:37 incredible odds to beat them. But this
00:32:37 --> 00:32:38 is taking the other perspective of
00:32:38 --> 00:32:40 another species kind of looking at us
00:32:40 --> 00:32:41 and going, "Those humans are
00:32:41 --> 00:32:42 terrifying." And it's listing all the
00:32:42 --> 00:32:43 ways we are. You know, we're an
00:32:44 --> 00:32:46 exhaustion hunter. We didn't beat things
00:32:46 --> 00:32:48 by speed or anything. We'd follow them
00:32:48 --> 00:32:51 until they died of exhaustion because we
00:32:51 --> 00:32:54 can go longer than they can. We're un
00:32:54 --> 00:32:55 they were saying, you know, it's the
00:32:55 --> 00:32:57 only intelligent technological species
00:32:57 --> 00:32:58 that invented amputation before
00:32:58 --> 00:33:00 painkillers.
00:33:00 --> 00:33:02 >> You know, we've got things like this
00:33:02 --> 00:33:04 that are very bizarre about us. So that
00:33:04 --> 00:33:07 takes this perspective I've got of these
00:33:07 --> 00:33:09 things are a hurdle and you develop
00:33:09 --> 00:33:11 things you know that things are not
00:33:11 --> 00:33:12 onoff switch but they're more of a
00:33:12 --> 00:33:16 slider and the idea of will things
00:33:16 --> 00:33:18 naturally be developed in the same order
00:33:18 --> 00:33:19 and turns it around and said what would
00:33:19 --> 00:33:22 another species think looking at us and
00:33:22 --> 00:33:23 I always find that really good fun and
00:33:24 --> 00:33:25 it's effectively leads to the thing that
00:33:25 --> 00:33:28 humans are space and we're this terri
00:33:28 --> 00:33:31 terrifying weird little species and
00:33:31 --> 00:33:33 maybe that's what it'll turn out to
00:33:33 --> 00:33:36 Well, it yeah, look, I don't uh I don't
00:33:36 --> 00:33:39 dispute that because look how we treat
00:33:39 --> 00:33:42 each other or have treated each other um
00:33:42 --> 00:33:45 since civilization began. Basically, uh
00:33:45 --> 00:33:47 I I don't think you could add up how
00:33:47 --> 00:33:48 many wars we've fought against each
00:33:48 --> 00:33:50 other.
00:33:50 --> 00:33:53 I I don't think that would stop if we
00:33:53 --> 00:33:55 found another intelligent life form. I
00:33:55 --> 00:33:57 don't think we'd go in saying, "Hi, hey,
00:33:57 --> 00:33:59 we're really nice." I I got a feeling
00:33:59 --> 00:34:01 we'd, you know, it'd be a bit
00:34:01 --> 00:34:03 adversarial.
00:34:03 --> 00:34:05 >> It It's a really It is a really
00:34:05 --> 00:34:06 interesting one. It's one of the things
00:34:06 --> 00:34:08 that people factor into a lot of the
00:34:08 --> 00:34:11 discussions about the the rights and
00:34:11 --> 00:34:14 wrongs of active SETI. So active SETI is
00:34:14 --> 00:34:16 sending out a message saying, "Hi, we're
00:34:16 --> 00:34:18 here. Please talk to us." Whereas
00:34:18 --> 00:34:19 passive SETI is listening for people
00:34:19 --> 00:34:21 saying, "Please turn neighbors off.
00:34:21 --> 00:34:22 We're sick of seeing it." You know,
00:34:22 --> 00:34:23 they're effectively the two ways you can
00:34:23 --> 00:34:27 do SETI. There are a lot of people in
00:34:27 --> 00:34:28 the past that have argued that active
00:34:28 --> 00:34:30 set is a bad idea because it will
00:34:30 --> 00:34:31 attract the wrong kind of attention.
00:34:31 --> 00:34:33 >> Well, Steven Hawking certainly thought
00:34:33 --> 00:34:33 that.
00:34:34 --> 00:34:37 >> Um, and throwing no shade, I think the
00:34:37 --> 00:34:38 great Mark Camode, who's a film reviewer
00:34:38 --> 00:34:41 in the UK, um, often says, you know,
00:34:41 --> 00:34:43 other opinions are available. They're
00:34:43 --> 00:34:45 wrong, but they are available. I mean,
00:34:45 --> 00:34:47 this, I think, is a case of that. I
00:34:47 --> 00:34:49 think if any for me, and I will admit
00:34:49 --> 00:34:51 I'm an optimist. I'm also not exactly
00:34:51 --> 00:34:54 the world's most aggressive person, but
00:34:54 --> 00:34:55 for me, if you have survived as a
00:34:55 --> 00:34:58 species for long enough to be a thriving
00:34:58 --> 00:35:00 civilization to the point of wanting to
00:35:00 --> 00:35:02 communicate to the upsc upstarts that
00:35:02 --> 00:35:04 are broadcasting, you know, Big Brother
00:35:04 --> 00:35:06 and all the rest of it to the universe,
00:35:06 --> 00:35:08 that suggests that to some degree you've
00:35:08 --> 00:35:10 overcome your martiality. Um because I
00:35:10 --> 00:35:13 think for us to survive to the point
00:35:13 --> 00:35:15 where we're moving out into the stars
00:35:15 --> 00:35:17 will require us not to first wipe
00:35:17 --> 00:35:19 ourselves out. And the more advanced you
00:35:19 --> 00:35:22 get, the more you disperse probably,
00:35:22 --> 00:35:24 fingers crossed, hopefully, the less
00:35:24 --> 00:35:26 likely that becomes. Now, we look at the
00:35:26 --> 00:35:27 world around us today, and without
00:35:27 --> 00:35:29 digging into politics, there's always
00:35:29 --> 00:35:30 something nasty going on. There's
00:35:30 --> 00:35:32 >> many, many tragedies that are both
00:35:32 --> 00:35:34 frontline in the news and forgotten by
00:35:34 --> 00:35:38 the news. But I saw a great article few
00:35:38 --> 00:35:40 years ago that was arguing that you know
00:35:40 --> 00:35:42 when was the worst time to ever live and
00:35:42 --> 00:35:44 saying that actually despite the fact
00:35:44 --> 00:35:46 that all this war all this aggression
00:35:46 --> 00:35:48 all this violence is so front and center
00:35:48 --> 00:35:50 this is actually the safest era to live
00:35:50 --> 00:35:53 in that humanity's ever experienced the
00:35:53 --> 00:35:55 number of people dying before their time
00:35:55 --> 00:35:58 dying before they reach scessians is
00:35:58 --> 00:36:00 lower per thousand people up 100
00:36:00 --> 00:36:02 thousand people than ever before you
00:36:02 --> 00:36:04 have a much lower chance as an average
00:36:04 --> 00:36:05 person of ever fighting in a war have
00:36:06 --> 00:36:08 ever been murdered or assaulted.
00:36:08 --> 00:36:10 >> So, we're already moving that way if it
00:36:10 --> 00:36:12 doesn't feel like it. And so, to me,
00:36:12 --> 00:36:15 with that optimistic viewpoint, I would
00:36:15 --> 00:36:17 like to think that there is no reason
00:36:17 --> 00:36:19 for conflict and no reason for friction.
00:36:19 --> 00:36:22 And I think a lot of the arguments that
00:36:22 --> 00:36:25 humanity's future encounters with aliens
00:36:25 --> 00:36:28 must by necessity be violent is telling
00:36:28 --> 00:36:29 you more about people than it's telling
00:36:29 --> 00:36:31 you about aliens because it's saying
00:36:31 --> 00:36:32 when we look in the mirror, we see the
00:36:32 --> 00:36:35 angry snarling tribalist. rather than
00:36:35 --> 00:36:38 the rational modern human that is a
00:36:38 --> 00:36:40 veneer on top. We're still a tribal
00:36:40 --> 00:36:43 species. We're still the product of our
00:36:43 --> 00:36:45 evolution. And society is a veneer that
00:36:45 --> 00:36:48 we put on top of that as we learn to be
00:36:48 --> 00:36:50 better, to be the kind of thinking
00:36:50 --> 00:36:54 social ape, I guess. And the evidence is
00:36:54 --> 00:36:55 that over time we're getting better at
00:36:55 --> 00:36:57 that. Even though we're now more capable
00:36:57 --> 00:36:59 of killing each other than we ever were
00:36:59 --> 00:36:59 before.
00:37:00 --> 00:37:00 >> Yeah.
00:37:00 --> 00:37:01 >> We're doing it less often.
00:37:01 --> 00:37:03 >> Yes, we are. All right. All right, we'll
00:37:03 --> 00:37:05 take a quick breather because I want to
00:37:05 --> 00:37:10 get into the um the area of u finding
00:37:10 --> 00:37:12 this life beyond our solar system. How
00:37:12 --> 00:37:14 how are we going to do it, where we're
00:37:14 --> 00:37:15 going to look, and what we've got to
00:37:15 --> 00:37:17 look for. That's all coming up on this
00:37:17 --> 00:37:21 edition of Space Nuts.
00:37:21 --> 00:37:23 >> Roger. Also,
00:37:23 --> 00:37:24 >> Space Nuts.
00:37:24 --> 00:37:26 >> So, Jotty, look, lead the way. Where do
00:37:26 --> 00:37:28 you want to go from here? We got to uh
00:37:28 --> 00:37:31 this is our final segment. So, um I
00:37:31 --> 00:37:33 suppose if you're going to try and find
00:37:33 --> 00:37:36 life beyond our solar system, uh you got
00:37:36 --> 00:37:39 to find the right environment, um you
00:37:39 --> 00:37:41 know, rocky planet, habitable zone
00:37:41 --> 00:37:43 perhaps, um
00:37:44 --> 00:37:45 >> and and there's a lot more to it than
00:37:45 --> 00:37:48 that. It's not just a planet with
00:37:48 --> 00:37:51 perhaps liquid water on its surface.
00:37:51 --> 00:37:53 There's you got to have, I suppose, the
00:37:53 --> 00:37:55 right kind of star. You don't want a red
00:37:55 --> 00:37:57 dwarf because you probably just, you
00:37:57 --> 00:38:00 know, get really bad sunburn. Uh there's
00:38:00 --> 00:38:02 a lot to take into account.
00:38:02 --> 00:38:03 >> There's a huge amount of depth to it.
00:38:03 --> 00:38:05 And I think as we saw with the previous
00:38:05 --> 00:38:07 episode, we could have talked another
00:38:07 --> 00:38:09 hour and we could have talked another
00:38:09 --> 00:38:10 week. To be honest, when we're talking
00:38:10 --> 00:38:12 about this stuff, one of the things I
00:38:12 --> 00:38:15 most adore about science is the infinite
00:38:15 --> 00:38:17 complexity. So you ask a question when
00:38:17 --> 00:38:18 you get an answer. That isn't it. But
00:38:18 --> 00:38:21 you get another 10 questions. And the
00:38:21 --> 00:38:22 more you know about a subject, the more
00:38:22 --> 00:38:24 complexity there is. To me, that's just
00:38:24 --> 00:38:26 a wonder. And that's fascinating. And
00:38:26 --> 00:38:28 this is a really good example of that.
00:38:28 --> 00:38:32 Now, one of my strongest arguments
00:38:32 --> 00:38:36 through my career has been that we can't
00:38:36 --> 00:38:37 just when we're trying to think about
00:38:37 --> 00:38:39 where we're going to search for life
00:38:39 --> 00:38:41 beyond the solar system, use a habitable
00:38:41 --> 00:38:43 zone and that's it. You know, it seems
00:38:43 --> 00:38:45 like a lot of coverage and a lot of
00:38:46 --> 00:38:48 papers just go earthlike planet found in
00:38:48 --> 00:38:50 the habitable zone. Wee and and that's
00:38:50 --> 00:38:53 about it. Now, the habitable zone has
00:38:53 --> 00:38:55 become a really effective communication
00:38:55 --> 00:38:56 tool in much the same way the Drake
00:38:56 --> 00:38:59 equation has. The Drake equation is this
00:38:59 --> 00:39:00 fabulous tool with all the sliders where
00:39:00 --> 00:39:03 you can make your own inhabited universe
00:39:03 --> 00:39:05 with lots of few aliens by varying the
00:39:05 --> 00:39:08 variables. The habitable zone has become
00:39:08 --> 00:39:10 another of these catch all kind of
00:39:10 --> 00:39:12 visualizations and it's born of the idea
00:39:12 --> 00:39:14 that life needs liquid water
00:39:14 --> 00:39:17 >> with the implicit extension of that that
00:39:17 --> 00:39:19 life needs liquid water on a planet's
00:39:19 --> 00:39:22 surface. Now that's initially motivated
00:39:22 --> 00:39:23 by the fact that the earth is the only
00:39:23 --> 00:39:25 place with life and back when this was
00:39:26 --> 00:39:27 being discussed the only place with
00:39:27 --> 00:39:29 liquid water that we knew. So therefore
00:39:29 --> 00:39:31 it was natural to say you need surface
00:39:31 --> 00:39:33 liquid water. As we discussed earlier
00:39:33 --> 00:39:34 there are plenty of places in the solar
00:39:34 --> 00:39:36 system that do not have liquid water on
00:39:36 --> 00:39:38 the surface but do have it underneath.
00:39:38 --> 00:39:40 They've got soft centers. But the
00:39:40 --> 00:39:43 habitable zone says you need liquid
00:39:43 --> 00:39:45 water on the surface of a planet for
00:39:46 --> 00:39:47 that planet to be considered suitable
00:39:47 --> 00:39:49 for life to be habitable.
00:39:49 --> 00:39:52 Now, that isn't entirely true, but for
00:39:52 --> 00:39:54 the purposes of this, it's still useful
00:39:54 --> 00:39:57 because life buried beneath ice is so
00:39:57 --> 00:39:59 hard to find that we can't find it in
00:39:59 --> 00:40:00 our own solar system because the ice is
00:40:00 --> 00:40:02 in the way. We wouldn't have a chance to
00:40:02 --> 00:40:03 run planets around other stars. So, even
00:40:04 --> 00:40:05 though I think the habitable zone is a
00:40:06 --> 00:40:07 big oversimplification, I see merit to
00:40:08 --> 00:40:10 it because life on a planet's surface
00:40:10 --> 00:40:13 with only atmosphere above is much more
00:40:13 --> 00:40:15 likely to be detectable than life burden
00:40:15 --> 00:40:16 the interior. So, fair enough, we'll go
00:40:16 --> 00:40:19 with it. The idea of the habitable zone
00:40:19 --> 00:40:21 though is that the closer you are to a
00:40:21 --> 00:40:22 star, the hotter you are. The further
00:40:22 --> 00:40:24 away you are, the cooler you are. And
00:40:24 --> 00:40:25 just like Goldilocks and the three
00:40:26 --> 00:40:27 bears, which why it's often called the
00:40:27 --> 00:40:28 Goldilock zone, there's a place where
00:40:28 --> 00:40:30 it's just right. It's not too hot, not
00:40:30 --> 00:40:31 too cold,
00:40:31 --> 00:40:32 >> and therefore there could be liquid
00:40:32 --> 00:40:35 water on the surface of the planet. Now,
00:40:35 --> 00:40:36 a lot of the time when people say a
00:40:36 --> 00:40:39 planet is in the habitable zone,
00:40:39 --> 00:40:42 that's often taken as meaning that
00:40:42 --> 00:40:44 planet could and potentially will have
00:40:44 --> 00:40:46 liquid water on the surface. But
00:40:46 --> 00:40:48 actually what it's saying is if you took
00:40:48 --> 00:40:51 the Earth as the Earth is today and put
00:40:51 --> 00:40:53 it in that system, would it still look
00:40:53 --> 00:40:54 like the Earth? Would it have liquid
00:40:54 --> 00:40:58 water on its surface? Now we've extended
00:40:58 --> 00:41:00 a bit beyond that. There are a couple of
00:41:00 --> 00:41:01 fabulous papers bit more than a decade
00:41:01 --> 00:41:03 old now that set what are our very
00:41:04 --> 00:41:05 contemporary scientific mathematical
00:41:05 --> 00:41:08 definitions of the habitable zone that
00:41:08 --> 00:41:10 people use for their papers. And they
00:41:10 --> 00:41:12 take the flux from the star, take into
00:41:12 --> 00:41:13 account the different colors of the
00:41:13 --> 00:41:16 stars. And there are two versions.
00:41:16 --> 00:41:17 There's the optimistic and conservative
00:41:18 --> 00:41:20 versions where the optimistic version is
00:41:20 --> 00:41:22 a wider set of distances and the
00:41:22 --> 00:41:24 conservative version is a smaller set of
00:41:24 --> 00:41:27 distances. But it effectively uses Venus
00:41:27 --> 00:41:29 and Mars as a roughing edge in our solar
00:41:29 --> 00:41:31 system and then scales that window up
00:41:31 --> 00:41:32 and down depending on the kind of star
00:41:32 --> 00:41:34 you're around.
00:41:34 --> 00:41:37 >> But that illustrates immediately
00:41:37 --> 00:41:39 that this is an oversimplification
00:41:39 --> 00:41:40 because you can do a thought experiment.
00:41:40 --> 00:41:42 Let's take our solar system. Venus is
00:41:42 --> 00:41:45 way too hot. Mars is way too cold and
00:41:45 --> 00:41:46 the Earth is just right. All well and
00:41:46 --> 00:41:49 good. Swap the Earth. Sorry, swap Mars
00:41:49 --> 00:41:51 and Venus around. If you put Venus where
00:41:51 --> 00:41:53 Mars is, Venus's thick atmosphere and
00:41:53 --> 00:41:54 greenhouse effect wouldn't mean it would
00:41:54 --> 00:41:56 be warm enough liquid water on the
00:41:56 --> 00:41:57 surface. It wouldn't have cooled as much
00:41:57 --> 00:42:01 as Mars. So Venus would be habitable on
00:42:01 --> 00:42:04 the surface outside the habitable zone.
00:42:04 --> 00:42:06 If you put Mars where Venus is, with its
00:42:06 --> 00:42:07 very thin and tenuous atmosphere, it
00:42:07 --> 00:42:10 doesn't have much greenhouse effect at
00:42:10 --> 00:42:12 all. Mars would potentially still be
00:42:12 --> 00:42:15 habitable where Venus is when Venus
00:42:15 --> 00:42:17 isn't. And so that's immediately
00:42:17 --> 00:42:19 pointing that this story is actually
00:42:19 --> 00:42:21 significantly more complex.
00:42:21 --> 00:42:21 >> Yeah.
00:42:21 --> 00:42:25 >> That you can't just say, let's calculate
00:42:25 --> 00:42:26 the habitable zone. Let's calculate the
00:42:26 --> 00:42:29 equilibrium temperature on a planet,
00:42:29 --> 00:42:31 which is a temperature it would have if
00:42:31 --> 00:42:33 it didn't have a greenhouse effect that
00:42:33 --> 00:42:35 it was a certain reflectivity and it was
00:42:35 --> 00:42:37 in equilibrium with the light coming in
00:42:37 --> 00:42:39 and the light going out. And if that
00:42:39 --> 00:42:40 temperature is from about minus20
00:42:40 --> 00:42:42 upwards, it's probably warm enough for
00:42:42 --> 00:42:43 water because, well, you'll have a bit
00:42:43 --> 00:42:46 of an atmosphere. To me, that's never
00:42:46 --> 00:42:48 been enough. Now, the reason it's really
00:42:48 --> 00:42:50 important, at least from my perspective,
00:42:50 --> 00:42:53 is that finding planets is hard. We'll
00:42:53 --> 00:42:55 talk about that in another episode, but
00:42:55 --> 00:42:58 once you find the first of something,
00:42:58 --> 00:43:00 astronomy, history, and probably every
00:43:00 --> 00:43:01 other form of scientific endeavor,
00:43:01 --> 00:43:02 history tells us, finding the first of
00:43:02 --> 00:43:04 something is hard. But once you've got
00:43:04 --> 00:43:06 one, you quickly find more and more as
00:43:06 --> 00:43:08 your technology gets better. Finding
00:43:08 --> 00:43:10 evidence of life on a planet that is
00:43:10 --> 00:43:13 similar to the Earth is fundamentally at
00:43:13 --> 00:43:15 least an order of magnitude if not more
00:43:15 --> 00:43:18 harder than finding that planet was. So
00:43:18 --> 00:43:20 it'll take time for our technology to
00:43:20 --> 00:43:22 get good enough to search comfortably
00:43:22 --> 00:43:24 for life elsewhere. So initially that
00:43:24 --> 00:43:26 search is going to be very restricted
00:43:26 --> 00:43:28 because we've got limited resources. So
00:43:28 --> 00:43:30 you're only going to be able to look at
00:43:30 --> 00:43:32 a few planets aggressively at first to
00:43:32 --> 00:43:34 try and tease out any indication of
00:43:34 --> 00:43:37 life. But you're going to have loads to
00:43:37 --> 00:43:38 choose from. How should you choose?
00:43:38 --> 00:43:40 Well, to me, it can't just be the
00:43:40 --> 00:43:44 habitable zone.
00:43:44 --> 00:43:47 >> Yeah, that's a valid point. Um, and and
00:43:47 --> 00:43:50 we've reached a point where we've found
00:43:50 --> 00:43:52 thousands upon thousands of exoplanets
00:43:52 --> 00:43:54 and counting. Like, we haven't stopped.
00:43:54 --> 00:43:55 We're finding them more and more and
00:43:56 --> 00:43:58 more often of all different shapes of
00:43:58 --> 00:44:02 sides sizes. Um,
00:44:02 --> 00:44:04 some rocky planets, they've been harder
00:44:04 --> 00:44:06 to find cuz they're they're usually much
00:44:06 --> 00:44:09 smaller and and don't sort of indicate
00:44:09 --> 00:44:12 themselves like a gas giant does. But
00:44:12 --> 00:44:15 we're getting better at finding uh rocky
00:44:15 --> 00:44:17 planets. Um,
00:44:17 --> 00:44:20 I suppose the big question is given how
00:44:20 --> 00:44:23 much we are finding, how do you identify
00:44:23 --> 00:44:25 prime targets for life?
00:44:25 --> 00:44:28 >> Yeah. And that is what the paper that I
00:44:28 --> 00:44:29 put together with Barry Jones back in
00:44:29 --> 00:44:33 2010 was all about. So Barry was a very
00:44:33 --> 00:44:34 dear friend of mine. He was my boss when
00:44:34 --> 00:44:36 I moved to the Open University from 2006
00:44:36 --> 00:44:38 to 2009. I think he knew Fred very well
00:44:38 --> 00:44:40 as well. So you can always mention to
00:44:40 --> 00:44:42 Fred that we talked about Barry. I
00:44:42 --> 00:44:44 started work at the Open University in
00:44:44 --> 00:44:45 2006 on the day Barry was forced to
00:44:46 --> 00:44:47 retire by the government because he'd
00:44:47 --> 00:44:50 hit 67. So he hired me and promptly
00:44:50 --> 00:44:53 retired but um he kept working anyway as
00:44:53 --> 00:44:56 ameritus professor. And Barry and I did
00:44:56 --> 00:44:57 a lot of work on this during my time
00:44:57 --> 00:44:59 there. Barry unfortunately passed away a
00:44:59 --> 00:45:00 little bit more than a decade ago. So
00:45:00 --> 00:45:03 he's fondly remembered. I organized a an
00:45:03 --> 00:45:05 award in the UK in his memory every
00:45:05 --> 00:45:07 couple of years. What we did in this
00:45:07 --> 00:45:11 2010 paper was to essentially have the
00:45:11 --> 00:45:13 thought process we just outlined. So,
00:45:13 --> 00:45:15 we're going to have a huge number of
00:45:16 --> 00:45:18 potential exo earths, planets that could
00:45:18 --> 00:45:20 potentially be Earthlike that could be
00:45:20 --> 00:45:23 places to look for life, but we're only
00:45:23 --> 00:45:24 going to be able to search a handful of
00:45:24 --> 00:45:27 them initially. So, what should we do to
00:45:27 --> 00:45:29 select the best target? Now, obviously,
00:45:29 --> 00:45:31 the closer the planet's hosts are is to
00:45:32 --> 00:45:33 the solar system, the easier the
00:45:33 --> 00:45:35 observations will be. That's just a
00:45:35 --> 00:45:37 fundamental thing of if you're twice as
00:45:37 --> 00:45:39 far away, we only receive a quarter as
00:45:39 --> 00:45:41 much light from you. But also, if you're
00:45:41 --> 00:45:42 twice as far away, the separation
00:45:42 --> 00:45:44 between the planet and the star on the
00:45:44 --> 00:45:47 sky will be half as much because the
00:45:47 --> 00:45:49 angle gets smaller the further away you
00:45:49 --> 00:45:51 go essentially. And we will want targets
00:45:51 --> 00:45:52 that are far enough from the star in the
00:45:52 --> 00:45:54 sky that with future missions like
00:45:54 --> 00:45:55 potentially the habitable world's
00:45:55 --> 00:45:57 observatory, we can separate the light
00:45:57 --> 00:45:58 from the planet from the light from the
00:45:58 --> 00:46:01 star. So, probably even more important
00:46:01 --> 00:46:03 than the habitable zone is this
00:46:03 --> 00:46:06 proximity thing. The planets in the main
00:46:06 --> 00:46:08 found by the Kepler space telescope
00:46:08 --> 00:46:10 won't be suitable for this search
00:46:10 --> 00:46:12 because they're mainly very far from the
00:46:12 --> 00:46:14 sun and so therefore they'll be very
00:46:14 --> 00:46:16 hard to study. We want to look locally.
00:46:16 --> 00:46:18 That's a given,
00:46:18 --> 00:46:20 but we want to look for places where
00:46:20 --> 00:46:22 there is the possibility of liquid water
00:46:22 --> 00:46:24 on the surface because that means that
00:46:24 --> 00:46:25 the life will be in contact with the
00:46:25 --> 00:46:27 atmosphere and that might generate a
00:46:27 --> 00:46:28 signature we can detect in the
00:46:28 --> 00:46:29 atmosphere.
00:46:29 --> 00:46:30 >> And that's where the habitable zone
00:46:30 --> 00:46:33 comes from. But there's actually much
00:46:33 --> 00:46:35 more to it than that I think. And I'm
00:46:35 --> 00:46:36 far from able to give an exhaustive list
00:46:36 --> 00:46:38 because I'm not an expert in all all
00:46:38 --> 00:46:41 areas of astronomy. But we decided to
00:46:41 --> 00:46:44 put together a review paper which about
00:46:44 --> 00:46:46 32 pages long, probably a little bit
00:46:46 --> 00:46:48 outdated now because science has moved
00:46:48 --> 00:46:51 forward, but was saying effectively you
00:46:51 --> 00:46:54 can't just use a habitable zone. We need
00:46:54 --> 00:46:56 to think about all of the different
00:46:56 --> 00:46:58 factors that can contribute to make a
00:46:58 --> 00:46:59 planet more or less suitable for life.
00:46:59 --> 00:47:02 Now, many of these have been in the past
00:47:02 --> 00:47:04 suggested as that onoff switch. And I do
00:47:04 --> 00:47:06 think that they're more sliders like the
00:47:06 --> 00:47:07 numbers in the Drake equation or sliders
00:47:07 --> 00:47:10 on a mixing desk. But there are a lot of
00:47:10 --> 00:47:11 different things that have been
00:47:11 --> 00:47:13 suggested. And as I dug into the paper,
00:47:13 --> 00:47:14 there were even more than I thought of.
00:47:14 --> 00:47:17 You can broadly break them down into
00:47:17 --> 00:47:19 four areas. The first is galactic
00:47:19 --> 00:47:22 influences. So the impact of the galaxy
00:47:22 --> 00:47:24 itself, where you are in the galaxy,
00:47:24 --> 00:47:26 stuff like that. You've then got stellar
00:47:26 --> 00:47:28 influences, so the role of the star.
00:47:28 --> 00:47:30 You've got the planetary system. And
00:47:30 --> 00:47:31 then you've got the planet itself. So th
00:47:31 --> 00:47:34 those the kind of four broad areas. The
00:47:34 --> 00:47:37 galactic influences one is probably the
00:47:37 --> 00:47:38 least useful and the least well
00:47:38 --> 00:47:40 constrained. But the idea of the
00:47:40 --> 00:47:42 galactic influence is tied a bit to a
00:47:42 --> 00:47:44 theory that's been put forward by a few
00:47:44 --> 00:47:45 people called the galactic habitable
00:47:45 --> 00:47:50 zone. It's an idea that ties back to the
00:47:50 --> 00:47:51 origin of stars and planets and also to
00:47:51 --> 00:47:53 the dangers that are experienced because
00:47:53 --> 00:47:55 of your environment. The idea that as
00:47:55 --> 00:47:57 time goes on, the universe is becoming
00:47:57 --> 00:48:00 more metalrich. And by that I mean
00:48:00 --> 00:48:01 enriched in everything other than
00:48:01 --> 00:48:03 hydrogen and helium because generations
00:48:03 --> 00:48:05 of stars run their furnaces and turn the
00:48:05 --> 00:48:07 light elements to the heavy ones and put
00:48:07 --> 00:48:09 them back into the cosmos. You need a
00:48:09 --> 00:48:10 certain amount of heavy elements to form
00:48:10 --> 00:48:12 planets like the Earth and to have the
00:48:12 --> 00:48:15 carbon, nitrogen, phosphorus for life.
00:48:15 --> 00:48:17 So as time goes on, the universe getting
00:48:17 --> 00:48:19 more enriched is a good thing. But
00:48:19 --> 00:48:21 there's also possibilities that too much
00:48:21 --> 00:48:23 enrichment will change the chemistry or
00:48:23 --> 00:48:25 it will make planet formation too easy.
00:48:25 --> 00:48:27 There's all sorts. So you might have a
00:48:27 --> 00:48:30 sweet spot from that side of things. Now
00:48:30 --> 00:48:32 in the middle of the galaxy, star
00:48:32 --> 00:48:34 formation occurs at a more rapid pace
00:48:34 --> 00:48:36 and stars live and die quicker. So you
00:48:36 --> 00:48:39 get faster change in the abundance of
00:48:40 --> 00:48:42 materials. So you can imagine we have
00:48:42 --> 00:48:43 this concept in astronomy called
00:48:43 --> 00:48:45 metallicity which is the amount it's
00:48:46 --> 00:48:47 usually measured in the amount of
00:48:47 --> 00:48:49 hydrogen compared to the amount of iron
00:48:49 --> 00:48:51 in a star and that gives you a number on
00:48:51 --> 00:48:53 a logarithmic scale and that is a an
00:48:54 --> 00:48:56 approximation to when the star formed
00:48:56 --> 00:48:57 and how enriched the world was at the
00:48:57 --> 00:48:59 time and as time goes on things get more
00:48:59 --> 00:49:02 and more metalrich within our galaxy
00:49:02 --> 00:49:03 you'd expect there to be a gradient in
00:49:03 --> 00:49:04 this. So the things near the middle will
00:49:04 --> 00:49:06 be much more enriched in heavy elements
00:49:06 --> 00:49:08 of things near the outer edge and
00:49:08 --> 00:49:09 there's probably sweet spot in the
00:49:10 --> 00:49:12 middle that moves outwards over time
00:49:12 --> 00:49:13 where conditions to form planets like
00:49:14 --> 00:49:15 the earth and planetary systems like the
00:49:15 --> 00:49:18 solar system are perfect. So that's part
00:49:18 --> 00:49:20 of the galactic habitable zone idea. The
00:49:20 --> 00:49:22 other idea is that if you're too close
00:49:22 --> 00:49:25 in and the stellar density is too high,
00:49:25 --> 00:49:26 eventually the stellar density gets so
00:49:26 --> 00:49:28 high that the likelihood of life being
00:49:28 --> 00:49:31 exterminated by nearby supernovi or
00:49:31 --> 00:49:32 planetary systems being stripped and
00:49:32 --> 00:49:34 disrupted becomes too high. So there's
00:49:34 --> 00:49:36 always been this idea that location
00:49:36 --> 00:49:39 within the galaxy is important. The
00:49:40 --> 00:49:42 challenge to that is twofold. Firstly,
00:49:42 --> 00:49:44 the proximity argument. We're going to
00:49:44 --> 00:49:45 have to look at stars that are very
00:49:45 --> 00:49:47 nearby which are all at the same
00:49:47 --> 00:49:48 distance from in the middle of the
00:49:48 --> 00:49:51 galaxy as we are. So where you are in
00:49:51 --> 00:49:54 the galaxy won't realistically impact
00:49:54 --> 00:49:55 this search because we're going to be
00:49:55 --> 00:49:57 looking locally. The other things though
00:49:57 --> 00:49:59 is that stars have a huge degree of
00:49:59 --> 00:50:01 mobility. There was a recent story
00:50:01 --> 00:50:03 talking about finding s solar twins,
00:50:03 --> 00:50:05 stars that have the same chemistry as
00:50:05 --> 00:50:07 the sun that may have formed with the
00:50:07 --> 00:50:09 sun and a suggestion that the sun and
00:50:10 --> 00:50:11 other stars may have formed as much as
00:50:11 --> 00:50:13 10 light years nearer the middle of
00:50:13 --> 00:50:15 the galaxy than we are now. Stars are
00:50:15 --> 00:50:17 getting scattered inwards and outwards.
00:50:17 --> 00:50:19 So seeing a star here now doesn't imply
00:50:19 --> 00:50:21 that it's always been here.
00:50:21 --> 00:50:21 >> Yeah.
00:50:21 --> 00:50:24 >> So the galactic influences I'm not going
00:50:24 --> 00:50:25 to go into really any more than that,
00:50:25 --> 00:50:27 but it's worth knowing that they're
00:50:27 --> 00:50:28 there. It's worth knowing that it's
00:50:28 --> 00:50:30 point of discussion and that there is
00:50:30 --> 00:50:32 good research going on about this. It's
00:50:32 --> 00:50:34 really interesting area, but it doesn't,
00:50:34 --> 00:50:36 I think, impact our initial search for
00:50:36 --> 00:50:39 life because we're going to be searching
00:50:39 --> 00:50:41 our local area. So, it's a bit like me
00:50:41 --> 00:50:42 saying I want to search for signs of
00:50:42 --> 00:50:44 life on Earth. It's a lot easier for me
00:50:44 --> 00:50:47 to search in King Soap where I live than
00:50:47 --> 00:50:50 to search in Mumbai or in London, places
00:50:50 --> 00:50:52 like this. You've got to look locally.
00:50:52 --> 00:50:54 Now, talking about that, you know, what
00:50:54 --> 00:50:55 would I expect to find?
00:50:55 --> 00:50:58 you know the people in King have not all
00:50:58 --> 00:50:59 but many of them have a similar
00:50:59 --> 00:51:01 background to me formed in similar ways
00:51:01 --> 00:51:03 with similar culture all the rest of it
00:51:03 --> 00:51:06 so this it's a not a great analogy I
00:51:06 --> 00:51:08 admit but we've got to look locally so
00:51:08 --> 00:51:11 the galactic influences stuff is
00:51:11 --> 00:51:15 interesting but I wouldn't say it is a
00:51:15 --> 00:51:18 big factor but it's worth noting I guess
00:51:18 --> 00:51:22 >> so that leads us on to um I don't know
00:51:22 --> 00:51:25 finding the right targets uh And and if
00:51:25 --> 00:51:28 we do find those targets,
00:51:28 --> 00:51:31 what what do we do then to look for
00:51:31 --> 00:51:33 potential life on those targets?
00:51:33 --> 00:51:34 >> Absolutely. And that's a very hard
00:51:34 --> 00:51:36 question. Now, in terms of finding the
00:51:36 --> 00:51:37 right targets, there's a lot that comes
00:51:38 --> 00:51:43 into it from the star itself. Now, stars
00:51:43 --> 00:51:45 live very long lives. First question
00:51:45 --> 00:51:47 then is how old is a star? Now, if we
00:51:47 --> 00:51:49 look at life on Earth, the oldest
00:51:49 --> 00:51:51 fossils on Earth that are widely
00:51:51 --> 00:51:52 accepted are about 3 and a half thousand
00:51:52 --> 00:51:54 million years old are in the Pilra,
00:51:54 --> 00:51:56 which is about a billion years after the
00:51:56 --> 00:51:58 Earth formed. There are some that are
00:51:58 --> 00:52:00 older that are still controversial,
00:52:00 --> 00:52:01 possibly as old as 4 billion years. But
00:52:01 --> 00:52:04 if we take the 3 1/2 billion years as a
00:52:04 --> 00:52:06 threshold and we do what we're doing
00:52:06 --> 00:52:07 with the liquid water thing and we say
00:52:07 --> 00:52:09 we expect life to follow a similar path
00:52:09 --> 00:52:11 to us, the fact that it took a billion
00:52:11 --> 00:52:13 years for life to get established enough
00:52:13 --> 00:52:15 to leave fossils we could find possibly
00:52:15 --> 00:52:16 means that it might have taken a similar
00:52:16 --> 00:52:18 length of time for that life to modify
00:52:18 --> 00:52:19 its environment enough to be detectable
00:52:20 --> 00:52:21 from elsewhere. So we can put an
00:52:21 --> 00:52:24 arbitrary kind of timer here saying that
00:52:24 --> 00:52:26 any planetary system younger than say a
00:52:26 --> 00:52:29 billion years may have planets that are
00:52:29 --> 00:52:30 suitable for life but that life might
00:52:30 --> 00:52:32 have not had enough time to get
00:52:32 --> 00:52:35 established yet. So that might
00:52:35 --> 00:52:37 immediately say that's not as good a
00:52:38 --> 00:52:39 place to look as a star that is more
00:52:39 --> 00:52:41 like the age of the sun where life's had
00:52:41 --> 00:52:43 four billion years to get going. Now
00:52:43 --> 00:52:46 tied to that is the fact that the lives
00:52:46 --> 00:52:48 of stars are very dependent on their
00:52:48 --> 00:52:50 mass. So the more massive a star is, the
00:52:50 --> 00:52:52 brighter it shines, but the shorter its
00:52:52 --> 00:52:55 life is. And at a very rough level, this
00:52:55 --> 00:52:56 number varies a little bit depending on
00:52:56 --> 00:52:58 the mass of the star. But typically the
00:52:58 --> 00:53:00 luminosity of a star is proportional to
00:53:00 --> 00:53:03 its mass to the power four. So if you've
00:53:03 --> 00:53:04 got a star that is 10 times the mass of
00:53:04 --> 00:53:06 the sun, it will be roughly 10 times
00:53:06 --> 00:53:09 brighter than the sun. But these stars
00:53:09 --> 00:53:10 are burning their own material. They're
00:53:10 --> 00:53:12 turning hydrogen to helium and they're
00:53:12 --> 00:53:14 made of hydrogen. So a star that is 10
00:53:14 --> 00:53:16 times the mass of the sun will only have
00:53:16 --> 00:53:18 10 times as much fuel as a sun. But it's
00:53:18 --> 00:53:21 burning that fuel 10 times quicker,
00:53:21 --> 00:53:23 which means it'll run out a lot quicker.
00:53:23 --> 00:53:24 And what that means is that the more
00:53:24 --> 00:53:26 massive a star is, the longer, the
00:53:26 --> 00:53:28 shorter its life will be. And the less
00:53:28 --> 00:53:30 massive a star is, the longer its life
00:53:30 --> 00:53:33 will be. That means that beyond a
00:53:33 --> 00:53:35 certain stellar mass, the star will die
00:53:35 --> 00:53:38 before that billionyear cutoff. So we
00:53:38 --> 00:53:39 can probably rule out the most massive
00:53:39 --> 00:53:41 stars. They'll just live fast, die
00:53:41 --> 00:53:43 young, and it's unlikely that life will
00:53:43 --> 00:53:45 get well enough established. On the flip
00:53:45 --> 00:53:47 side, the dim little red dwarfs will
00:53:47 --> 00:53:48 just go forever. You know, Proxima
00:53:48 --> 00:53:50 Centtory will still be traveling along
00:53:50 --> 00:53:52 in a trillion years when we're a distant
00:53:52 --> 00:53:54 memory. So, they might be a good place
00:53:54 --> 00:53:56 to look. The challenge there though is
00:53:56 --> 00:53:59 that those stars are quite active quite
00:53:59 --> 00:54:02 often. And to be in the habitable zone
00:54:02 --> 00:54:03 around them, you've got to be very close
00:54:03 --> 00:54:04 in because they're called little embers.
00:54:04 --> 00:54:06 You've got to snuggle up to the fire. So
00:54:06 --> 00:54:07 there's a lot of discussion about the
00:54:07 --> 00:54:10 fact that M dwarf planets planets around
00:54:10 --> 00:54:12 these coolest smallest stars are
00:54:12 --> 00:54:13 probably not ideal places to look for
00:54:13 --> 00:54:15 knife initially. Few reasons. One is
00:54:16 --> 00:54:17 that activity and a lot of discussions
00:54:18 --> 00:54:19 that the activity of red dwarfs when
00:54:19 --> 00:54:20 they're young could scour a planet's
00:54:20 --> 00:54:22 atmosphere away and that seems to have
00:54:22 --> 00:54:24 possibly been backed up with a trappist
00:54:24 --> 00:54:26 one planets that all seem to be airless
00:54:26 --> 00:54:29 worlds. The other is that those planets,
00:54:30 --> 00:54:31 if they are close enough in to be warm
00:54:31 --> 00:54:33 enough for liquid water on the surface,
00:54:33 --> 00:54:35 would have to be tidily locked like the
00:54:35 --> 00:54:37 moon is to the earth, which means
00:54:37 --> 00:54:38 they'll keep one face permanently
00:54:38 --> 00:54:39 pointed towards the star and the other
00:54:39 --> 00:54:42 permanently away, which may make it
00:54:42 --> 00:54:43 harder to look for light on them. It
00:54:43 --> 00:54:45 might be the case that any life would be
00:54:45 --> 00:54:47 on the sunwood side, and that's kind of
00:54:47 --> 00:54:49 hard to observe because when that side
00:54:49 --> 00:54:51 is best presented to us, it's near the
00:54:51 --> 00:54:54 star. So, that's challenging. Another
00:54:54 --> 00:54:56 thing that factors into it ties into
00:54:56 --> 00:54:57 something called the faint early sun
00:54:57 --> 00:55:01 paradox on Earth. The
00:55:01 --> 00:55:03 lives of stars, they shine brightly.
00:55:03 --> 00:55:05 Their brightness is measured compared to
00:55:05 --> 00:55:06 their mass, but their brightness
00:55:06 --> 00:55:09 increases with time. Stars get more
00:55:09 --> 00:55:10 luminous as they age a little bit. And
00:55:10 --> 00:55:13 it's a slow process. But with the sun,
00:55:13 --> 00:55:16 we think the sun was 30% dimmer when it
00:55:16 --> 00:55:19 was born to how it is now. So that means
00:55:19 --> 00:55:21 the earth at the time got 30% less
00:55:21 --> 00:55:24 energy which would have put it with its
00:55:24 --> 00:55:26 current atmosphere
00:55:26 --> 00:55:29 too cold to support life. Um that was
00:55:29 --> 00:55:30 offset by the fact we had a very
00:55:30 --> 00:55:32 different atmosphere then and a
00:55:32 --> 00:55:33 significant
00:55:33 --> 00:55:35 greenhouse effect which was lessened due
00:55:35 --> 00:55:38 to the influence of life stripping out
00:55:38 --> 00:55:39 carbon dioxide particularly from the
00:55:40 --> 00:55:41 atmosphere and keeping us mostly there
00:55:41 --> 00:55:44 and thereabouts. But what that means is
00:55:44 --> 00:55:47 that if we find a planet now and that
00:55:47 --> 00:55:48 planet is near the outer edge of the
00:55:48 --> 00:55:50 habitable zone, everybody will go,
00:55:50 --> 00:55:51 "Well, it's in the habitable zone.
00:55:51 --> 00:55:53 That's great." Whereas my question would
00:55:53 --> 00:55:55 then be, "But how long has it been in
00:55:55 --> 00:55:57 the habitable zone?" Because when the
00:55:57 --> 00:55:59 star was younger, it was a little bit
00:55:59 --> 00:56:01 dimmer. The habitable zone would have
00:56:01 --> 00:56:02 been closer in, and that planet might
00:56:02 --> 00:56:04 well have been outside it. So, I don't
00:56:04 --> 00:56:05 necessarily think that that 1
00:56:05 --> 00:56:08 billionyear clock would start until the
00:56:08 --> 00:56:09 planet was in the habitable zone. So
00:56:09 --> 00:56:11 we'll probably then be able to rule some
00:56:11 --> 00:56:14 planets out on the basis of the fact
00:56:14 --> 00:56:17 that they could be in the habitable zone
00:56:17 --> 00:56:18 now, but they haven't been full long
00:56:18 --> 00:56:19 enough.
00:56:19 --> 00:56:19 >> Yeah.
00:56:19 --> 00:56:21 >> So the star has all these effects. Never
00:56:21 --> 00:56:23 mind the fact that astronomers often
00:56:23 --> 00:56:25 joke that three out of every two stars
00:56:25 --> 00:56:28 are in a multiple star system. um
00:56:28 --> 00:56:30 multiple stars are very very common and
00:56:30 --> 00:56:32 that adds a whole extra level of
00:56:32 --> 00:56:35 complexity both to the understanding of
00:56:35 --> 00:56:37 the lives of the planets in those stars
00:56:37 --> 00:56:39 but also in our ability to study them
00:56:39 --> 00:56:41 because you've got more than one stars
00:56:41 --> 00:56:43 like to factor in all close together.
00:56:43 --> 00:56:45 It's much nastier and much more
00:56:45 --> 00:56:47 complicated. So there's a lot of ways
00:56:47 --> 00:56:49 that the stars can factor in and I think
00:56:49 --> 00:56:52 that's only a very very broad brush
00:56:52 --> 00:56:54 strokes for view. But you can see how
00:56:54 --> 00:56:56 what I'm thinking is you can bring in
00:56:56 --> 00:56:59 all these different ideas and have them
00:56:59 --> 00:57:01 as a slider. This kind of star could
00:57:01 --> 00:57:02 have planets around it with life, but
00:57:02 --> 00:57:05 it's not as good a target as this one.
00:57:05 --> 00:57:06 Now, everybody could build their own
00:57:06 --> 00:57:08 algorithm out of this, but I'd like to
00:57:08 --> 00:57:09 think that when we're trying to pick the
00:57:09 --> 00:57:12 target, you take into account the star
00:57:12 --> 00:57:14 that it's going around, how active it
00:57:14 --> 00:57:16 is. Is it a single star? Is it old
00:57:16 --> 00:57:19 enough? All these kind of factors. And
00:57:19 --> 00:57:21 then you can start looking at the
00:57:21 --> 00:57:23 planetary system that it's in. And
00:57:23 --> 00:57:24 there's a lot to talk about there, I
00:57:24 --> 00:57:25 think.
00:57:25 --> 00:57:30 >> Yes, absolutely. Uh and in our next um
00:57:30 --> 00:57:34 uh special um between Q&A episodes, we
00:57:34 --> 00:57:37 will um look more into um the the planet
00:57:37 --> 00:57:39 side of things. I I guess just to
00:57:39 --> 00:57:43 conclude um I'll throw one at you. Um
00:57:43 --> 00:57:45 and and this answer is always different
00:57:45 --> 00:57:47 depending on who you ask, but uh what do
00:57:47 --> 00:57:50 you think the odds are that we will find
00:57:50 --> 00:57:53 some form of life?
00:57:53 --> 00:57:56 >> Um I I'm an optimist. I think the answer
00:57:56 --> 00:57:58 to it will be yes, we will find some
00:57:58 --> 00:58:00 sort of life. I think the harder
00:58:00 --> 00:58:04 question is when. Now, if we find life
00:58:04 --> 00:58:06 in a million years time when we're not
00:58:06 --> 00:58:07 even human anymore, but we've hung
00:58:07 --> 00:58:09 around, we've managed to survive. That's
00:58:09 --> 00:58:10 not very edifying for me and you cuz
00:58:10 --> 00:58:13 it's a long time to wait. But as I said
00:58:13 --> 00:58:14 earlier on, I don't think it's a
00:58:14 --> 00:58:15 question of if, it's a question of when.
00:58:16 --> 00:58:19 Because I find it vanishingly improbable
00:58:19 --> 00:58:23 for us to be the only system with life.
00:58:23 --> 00:58:24 >> And it's a numbers game for me. You
00:58:24 --> 00:58:26 know, we've got a galaxy with between
00:58:26 --> 00:58:30 200 and 400 million stars. There are
00:58:30 --> 00:58:33 more galaxies in the visible universe
00:58:33 --> 00:58:35 certainly than there are planets in our
00:58:35 --> 00:58:37 galaxy. probably more than there are
00:58:37 --> 00:58:39 grains of sand in our galaxy. All of
00:58:39 --> 00:58:41 them with hundreds of thousands of
00:58:41 --> 00:58:43 millions of stars.
00:58:43 --> 00:58:45 To say that out of if you run the
00:58:45 --> 00:58:47 numbers you get sectillions,
00:58:47 --> 00:58:50 septillions, even octillions
00:58:50 --> 00:58:54 bonkersly full-on numbers of planets out
00:58:54 --> 00:58:56 there that were the only place that got
00:58:56 --> 00:58:58 life. That tells you that life is
00:58:58 --> 00:58:59 effectively impossible and we're a
00:58:59 --> 00:59:00 fluke.
00:59:00 --> 00:59:04 >> Now, that could be the case. If that's
00:59:04 --> 00:59:05 the case, what we've got here on Earth
00:59:05 --> 00:59:07 becomes even more precious and there is
00:59:07 --> 00:59:10 an even greater incentive for us to keep
00:59:10 --> 00:59:13 an eye on what we're doing so that Earth
00:59:13 --> 00:59:14 is still capable of hosting life in the
00:59:14 --> 00:59:17 future. But I think in reality, life
00:59:17 --> 00:59:19 will actually be more common than that.
00:59:19 --> 00:59:20 And you don't need to be much more
00:59:20 --> 00:59:22 common than that for life to be abundant
00:59:22 --> 00:59:25 in the galaxy. Let's imagine that life
00:59:25 --> 00:59:29 is found on one planet in 1 billion.
00:59:29 --> 00:59:31 That's billion with a B. So one in a
00:59:31 --> 00:59:33 thousand million. Now, we're finding
00:59:33 --> 00:59:35 that on average all stars have planets,
00:59:35 --> 00:59:37 probably have a number of planets. So,
00:59:37 --> 00:59:39 if we say roughly there are 10 planets
00:59:39 --> 00:59:41 per star, there will be four trillion
00:59:41 --> 00:59:43 planets in our galaxy. If one in a
00:59:43 --> 00:59:46 billion had life on it, that would mean
00:59:46 --> 00:59:49 there were 4 inhabited planets in
00:59:49 --> 00:59:50 our galaxy.
00:59:50 --> 00:59:52 >> Not a big number. The nearest one would
00:59:52 --> 00:59:54 be so far away in that case, we wouldn't
00:59:54 --> 00:59:56 find life for a long time. But life
00:59:56 --> 00:59:58 could be common and we still wouldn't
00:59:58 --> 01:00:00 find it. The more you increase that
01:00:00 --> 01:00:03 likelihood of life, the nearer the
01:00:03 --> 01:00:05 nearest examples will be and the sooner
01:00:05 --> 01:00:06 we'll find it. And that's why I think
01:00:06 --> 01:00:08 proximity will tell us a lot about the
01:00:08 --> 01:00:12 probability of life in that if we find
01:00:12 --> 01:00:15 life, the next step is to figure out we
01:00:15 --> 01:00:17 are not alone. We know we're not alone.
01:00:17 --> 01:00:19 How common is life? Now the other thing
01:00:19 --> 01:00:21 I think factors into it I think is a
01:00:21 --> 01:00:23 lovely kind of sci-fi thing to discuss
01:00:23 --> 01:00:24 all the way through you mentioned early
01:00:24 --> 01:00:27 on carbon based life and technologically
01:00:27 --> 01:00:30 advanced life and we drifted away the
01:00:30 --> 01:00:33 one place where I think that life that
01:00:33 --> 01:00:34 is different to us is something we could
01:00:34 --> 01:00:38 possibly find is siliconbased life now
01:00:38 --> 01:00:41 the reason for that is not from the
01:00:41 --> 01:00:45 point of view of um silicon people who
01:00:45 --> 01:00:48 have evolved in the way we have done I'm
01:00:48 --> 01:00:50 thinking more kind of second generation
01:00:50 --> 01:00:52 life. Now, our exploration of the solar
01:00:52 --> 01:00:54 system is done by our robot envoys and
01:00:54 --> 01:00:56 we're sending them near enough to home
01:00:56 --> 01:00:58 that we can tell them what to do.
01:00:58 --> 01:01:01 >> But we are developing to certain
01:01:01 --> 01:01:02 controversy at the current time. We're
01:01:02 --> 01:01:04 developing a greater and greater ability
01:01:04 --> 01:01:06 to develop things that can make
01:01:06 --> 01:01:07 decisions for themselves without human
01:01:07 --> 01:01:11 input. Things like AI and other systems.
01:01:11 --> 01:01:12 And if we get to the point where we want
01:01:12 --> 01:01:16 to explore around other stars, we'll
01:01:16 --> 01:01:18 need to develop spacecraft that have
01:01:18 --> 01:01:19 enough autonomy to make their own
01:01:19 --> 01:01:22 decisions. You go back to the idea, and
01:01:22 --> 01:01:23 I don't know what's happened to it in
01:01:23 --> 01:01:24 recent years, but the idea of project
01:01:24 --> 01:01:25 star where they made a little
01:01:25 --> 01:01:27 spacecraft, shot them off with laser,
01:01:27 --> 01:01:29 then they got to Proxima Centuri in 25
01:01:29 --> 01:01:31 years traveling at a fifth of the speed
01:01:31 --> 01:01:35 of light. You do that, they get to
01:01:35 --> 01:01:36 Proxima Centuri. If they've got to ask
01:01:36 --> 01:01:38 us what to do, they send a signal to us.
01:01:38 --> 01:01:40 takes 4 and a bit years to get here.
01:01:40 --> 01:01:42 Takes five years to get back and by the
01:01:42 --> 01:01:43 time it reaches them, they're a light
01:01:43 --> 01:01:44 year beyond the system. It's that well
01:01:44 --> 01:01:46 too late. So, we have to give them a
01:01:46 --> 01:01:48 certain level of autonomy. And the more
01:01:48 --> 01:01:49 complex their mission is going to be,
01:01:49 --> 01:01:52 the more autonomous it have to be. Which
01:01:52 --> 01:01:54 leads to the very science fiction idea
01:01:54 --> 01:01:57 that when we move out beyond the solar
01:01:57 --> 01:01:58 system, if we move out beyond the solar
01:01:58 --> 01:02:02 system, we will be preceded by a wave of
01:02:02 --> 01:02:06 life that is not us. That is our life
01:02:06 --> 01:02:08 that has a creator. that creator is
01:02:08 --> 01:02:10 humanity that is silicant based life
01:02:10 --> 01:02:11 that we send out whether they're
01:02:12 --> 01:02:14 vonoyman machines whether they are
01:02:14 --> 01:02:16 incredibly advanced AI machines without
01:02:16 --> 01:02:19 the capacity to reproduce themselves we
01:02:19 --> 01:02:22 will send out artificially
01:02:22 --> 01:02:25 built silicon life forms and again
01:02:25 --> 01:02:28 there's a a lovely fairly low stakes
01:02:28 --> 01:02:31 sci-fi series called the Bobbyverse
01:02:31 --> 01:02:33 um which follows that kind of idea in
01:02:33 --> 01:02:36 terms of future earth well guy in the
01:02:36 --> 01:02:38 current day dies but has in invested in
01:02:38 --> 01:02:41 cryogenics and his head is frozen and he
01:02:41 --> 01:02:43 wakes up and he's essentially put into a
01:02:43 --> 01:02:46 van machine and shot out into the stars
01:02:46 --> 01:02:47 and that that's a really interesting one
01:02:48 --> 01:02:49 because it's silicon based life that is
01:02:49 --> 01:02:51 also human. I mean figure that one out
01:02:51 --> 01:02:53 but it's good fun
01:02:53 --> 01:02:54 >> following again that very dangerous
01:02:54 --> 01:02:57 assumption that other life would follow
01:02:57 --> 01:02:58 the same pathway we follow and it seems
01:02:58 --> 01:03:00 like we are going down this AI and
01:03:00 --> 01:03:02 increasing complexity and increasing
01:03:02 --> 01:03:05 autonomy route. You then argue that
01:03:05 --> 01:03:07 other species sending out craft into the
01:03:08 --> 01:03:11 galaxy would send out autonomous
01:03:11 --> 01:03:14 intelligent silicon machines before they
01:03:14 --> 01:03:17 send themselves out. And therefore, you
01:03:17 --> 01:03:18 know, I'd think we're more likely if
01:03:18 --> 01:03:20 we're ever to bump into aliens to run
01:03:20 --> 01:03:22 into one of these probes or one of these
01:03:22 --> 01:03:24 machines rather than the aliens
01:03:24 --> 01:03:25 themselves. So I think there is a very
01:03:25 --> 01:03:27 real chance that if we find intelligent
01:03:27 --> 01:03:29 advanced life it could be siliconbased
01:03:29 --> 01:03:31 rather than carbon based but it's
01:03:31 --> 01:03:33 siliconbased life that was created by
01:03:33 --> 01:03:37 carbon based life which I mean leads to
01:03:37 --> 01:03:38 really interesting questions about
01:03:38 --> 01:03:40 philosophy and religion and all those
01:03:40 --> 01:03:42 kind of things which are not my forte
01:03:42 --> 01:03:44 but you know it does ask in interesting
01:03:44 --> 01:03:46 questions about origin and creation when
01:03:46 --> 01:03:47 you think about it from the context of
01:03:47 --> 01:03:49 that which is one of the things that's
01:03:49 --> 01:03:51 driven like I say a lot of wonderful and
01:03:51 --> 01:03:52 wonderfully entertaining sci-fi over the
01:03:52 --> 01:03:55 years. Yeah. Yeah. Look, as you said
01:03:55 --> 01:03:57 earlier, we could we could talk about
01:03:57 --> 01:04:01 this for a week, but we can't. Um, but
01:04:01 --> 01:04:03 uh I do uh want to direct people to your
01:04:03 --> 01:04:06 paper if uh people are interested in
01:04:06 --> 01:04:10 reading your paper from 2010. Uh it's uh
01:04:10 --> 01:04:12 called determining habitability, which
01:04:12 --> 01:04:15 exo earths should we search for life?
01:04:16 --> 01:04:18 And you can find it on the archive
01:04:18 --> 01:04:20 website. Is that right, Johnny?
01:04:20 --> 01:04:21 >> Yeah. So that was published in the
01:04:21 --> 01:04:23 international journal of astrobiology in
01:04:23 --> 01:04:24 2010. So the ones who want the kind of
01:04:24 --> 01:04:26 scientific reference it's international
01:04:26 --> 01:04:29 journal of astrobiology volume 9 page
01:04:29 --> 01:04:32 273 onwards. But um if you find it on
01:04:32 --> 01:04:34 NASA ads it'll give you the archive link
01:04:34 --> 01:04:37 which is the preprint version which
01:04:37 --> 01:04:39 basically means it's in my formatting
01:04:39 --> 01:04:41 rather than journal formatting. And this
01:04:41 --> 01:04:44 is it's actually a handier aside that
01:04:44 --> 01:04:47 I'm sure has been mentioned before. The
01:04:47 --> 01:04:51 way that a lot of science works has led
01:04:51 --> 01:04:53 to the creation of the most profitable
01:04:53 --> 01:04:57 and um and problematic um companies in
01:04:57 --> 01:04:58 the world which are the publishing
01:04:58 --> 01:05:00 companies. And so the way a scientist
01:05:00 --> 01:05:02 works is we do all this work da da da da
01:05:02 --> 01:05:04 hooray hoay huray. We then write a paper
01:05:04 --> 01:05:06 to tell the world about it. We send that
01:05:06 --> 01:05:08 off to a journal who gets another
01:05:08 --> 01:05:10 scientist to volunteer their time unpaid
01:05:10 --> 01:05:12 for free to referee it.
01:05:12 --> 01:05:13 >> Y
01:05:13 --> 01:05:15 >> then they charge typically the scientist
01:05:15 --> 01:05:16 who's written that paper money to
01:05:16 --> 01:05:18 publish that paper for them and then
01:05:18 --> 01:05:20 charge everybody for the privilege of
01:05:20 --> 01:05:22 reading it. So if I want the journal if
01:05:22 --> 01:05:24 I want to read the journal versions of
01:05:24 --> 01:05:26 my papers fortunately universities have
01:05:26 --> 01:05:28 paid access to a lot of journals but I'm
01:05:28 --> 01:05:31 fundamentally paying to read my own work
01:05:31 --> 01:05:35 and this is not ideal. I think partly
01:05:35 --> 01:05:36 because as a scientist, you know, I'm
01:05:36 --> 01:05:38 paid by taxpayers money. People are
01:05:38 --> 01:05:41 paying me to do this work. To me, it is
01:05:41 --> 01:05:42 really important that they know what
01:05:42 --> 01:05:44 we're doing. They know what they're
01:05:44 --> 01:05:45 getting for their money. And part of
01:05:46 --> 01:05:47 that is be a science communicator. And I
01:05:47 --> 01:05:49 encourage any scientists or budding
01:05:49 --> 01:05:51 scientists, don't just focus on the
01:05:51 --> 01:05:52 science. Focus on communication as well.
01:05:52 --> 01:05:53 Because if you do science, but can't
01:05:53 --> 01:05:55 communicate it, no one will know what
01:05:55 --> 01:05:58 you've done. But to get around that,
01:05:58 --> 01:06:00 what we do in astronomy and what many
01:06:00 --> 01:06:03 disciplines do is that we put preprints
01:06:04 --> 01:06:06 up on a publicly accessible free place.
01:06:06 --> 01:06:08 And it's in astronomy, it's just
01:06:08 --> 01:06:10 accepted that with very rare exceptions,
01:06:10 --> 01:06:12 journals will let you do this. So when
01:06:12 --> 01:06:15 we get our paper and we've written it,
01:06:15 --> 01:06:17 some disciplines in astronomy will put
01:06:17 --> 01:06:18 the paper up on the archive when it's
01:06:18 --> 01:06:21 submitted. Some will wait until it's
01:06:21 --> 01:06:22 accepted by the journal, when it's
01:06:22 --> 01:06:24 refereed. I've always waited till
01:06:24 --> 01:06:25 acceptance, but occasionally if you've
01:06:25 --> 01:06:27 made a big discovery, you want to stop
01:06:27 --> 01:06:29 somebody scooping you. You put it up at
01:06:29 --> 01:06:31 submission. There's a growing effort by
01:06:31 --> 01:06:32 scientists to put it up at submission to
01:06:32 --> 01:06:34 actively solicit feedback from the
01:06:34 --> 01:06:35 community to improve the work, which is
01:06:35 --> 01:06:38 good. But those papers go up on archive,
01:06:38 --> 01:06:40 a rxiv.
01:06:40 --> 01:06:41 >> Yeah.
01:06:41 --> 01:06:44 >> Um, be very careful. There is another
01:06:44 --> 01:06:46 platform out there where the letters in
01:06:46 --> 01:06:48 archive are shifted around which is
01:06:48 --> 01:06:51 where a community of people who espouse
01:06:51 --> 01:06:52 ideas that are not scientifically
01:06:52 --> 01:06:55 verifiable will put their work and
01:06:55 --> 01:06:56 publish their own little papers. It's a
01:06:56 --> 01:06:59 different thing but archive is a
01:06:59 --> 01:07:01 repository of freeto view things. So if
01:07:01 --> 01:07:04 you are searching for papers NASA's ads
01:07:04 --> 01:07:06 system is wonderful. When you click on a
01:07:06 --> 01:07:09 given paper in there, most of them, but
01:07:09 --> 01:07:10 not all of them, will have a line that
01:07:10 --> 01:07:12 says journal version or ads version, but
01:07:12 --> 01:07:14 there'll also be a line that says
01:07:14 --> 01:07:15 preprint. And if you click on the
01:07:15 --> 01:07:17 pre-print links, it will take you to the
01:07:17 --> 01:07:19 archive and allow you to read the paper
01:07:19 --> 01:07:21 for free. Just to be aware that that is
01:07:21 --> 01:07:24 a version some of the time before
01:07:24 --> 01:07:25 refereeing, most of the time after
01:07:26 --> 01:07:27 refereeing, but before publishing and
01:07:27 --> 01:07:29 edits effectively. So, the link you've
01:07:30 --> 01:07:32 got to that is the pre-print version of
01:07:32 --> 01:07:34 that paper. The other caution I give to
01:07:34 --> 01:07:36 people is that it is 16 years old. So
01:07:36 --> 01:07:38 all of the areas I talk about in it have
01:07:38 --> 01:07:41 moved on. We've learned more. We can
01:07:41 --> 01:07:42 talk a bit more about it next time as
01:07:42 --> 01:07:44 well. But always when you read things be
01:07:44 --> 01:07:47 conscious of the fact that science is
01:07:47 --> 01:07:49 fluid. Science changes. Our knowledge
01:07:49 --> 01:07:50 changes. I see just in the news
01:07:50 --> 01:07:54 recently, Jayen Isaac Isacson, who's I
01:07:54 --> 01:07:56 think the head guy at NASA at the
01:07:56 --> 01:07:57 minute, who's a wealthy
01:07:57 --> 01:08:00 multi-billionaire type guy, um is
01:08:00 --> 01:08:01 arguing that the US is wanting to
01:08:01 --> 01:08:03 strongly build a scientific case why
01:08:03 --> 01:08:05 Pluto should be restored as a planet
01:08:05 --> 01:08:07 because fundamentally we discovered it
01:08:07 --> 01:08:09 so it should still be a planet and Clyde
01:08:09 --> 01:08:12 Tombbo would be turning in his grave.
01:08:12 --> 01:08:15 That is what it is. But it's um it is
01:08:16 --> 01:08:18 important to keep in mind that science
01:08:18 --> 01:08:21 is fluid. It moves. Whereas once
01:08:21 --> 01:08:23 something is published that's static.
01:08:23 --> 01:08:26 >> It's a window on our knowledge at a time
01:08:26 --> 01:08:28 rather than necessarily the modern
01:08:28 --> 01:08:30 version. If I were to rewrite that paper
01:08:30 --> 01:08:33 now there'd be advances.
01:08:33 --> 01:08:36 >> Of course. Absolutely. But um yes um I
01:08:36 --> 01:08:38 think we're trying to arrange to put the
01:08:38 --> 01:08:39 link on the show notes. I'll just have
01:08:39 --> 01:08:42 to remind Hugh about that. We might wrap
01:08:42 --> 01:08:44 it up there. Jonty. fascinating topic
01:08:44 --> 01:08:46 and uh it's one we get a heck of a lot
01:08:46 --> 01:08:48 of questions about. So, um yeah,
01:08:48 --> 01:08:50 hopefully there's a bit of information
01:08:50 --> 01:08:53 in there to uh keep people's minds
01:08:53 --> 01:08:55 worring. Johnny, thanks very much. We
01:08:56 --> 01:08:57 will uh see you again real soon. It's an
01:08:58 --> 01:08:59 absolute pleasure. Thank you for having
01:08:59 --> 01:09:00 me.
01:09:00 --> 01:09:01 >> Professor Johnny her, professor of
01:09:01 --> 01:09:03 astrophysics at the University of
01:09:03 --> 01:09:05 Southern Queensland, standing in for
01:09:05 --> 01:09:07 Fred Watson. And thanks to Hugh in the
01:09:07 --> 01:09:09 studio. Uh Hugh couldn't be with us
01:09:09 --> 01:09:12 today. Um he got a bit confused. We we
01:09:12 --> 01:09:15 know of one planet where there is life.
01:09:15 --> 01:09:17 Hugh thought we meant that he was the
01:09:17 --> 01:09:19 only life form on the planet, so he
01:09:19 --> 01:09:21 didn't see any need to turn up today.
01:09:21 --> 01:09:23 And from me, Andrew Dunley, thanks for
01:09:23 --> 01:09:25 your company. We'll see you on the next
01:09:25 --> 01:09:27 episode of Space Nuts. Bye-bye.
01:09:27 --> 01:09:28 >> Space Nuts.
01:09:28 --> 01:09:30 >> You've been listening to the Space Nuts
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