1 00:00:03,040 --> 00:00:05,280 Speaker 1: Welcome to Stuff to Blow Your Mind, the production of 2 00:00:05,360 --> 00:00:14,800 Speaker 1: My Heart Radio. Hey, welcome to Stuff to Blow Your Mind. 3 00:00:14,960 --> 00:00:18,439 Speaker 1: My name is Robert Lamb, and I'm Joe McCormick. And 4 00:00:18,520 --> 00:00:21,800 Speaker 1: today we're going to be talking about a subject that 5 00:00:21,840 --> 00:00:24,000 Speaker 1: I've actually had on the radar for a while. This 6 00:00:24,079 --> 00:00:27,639 Speaker 1: is something that was making the rounds on science blogs 7 00:00:27,680 --> 00:00:30,720 Speaker 1: a few years back, and it has been suggested by 8 00:00:30,760 --> 00:00:33,159 Speaker 1: a number of different listeners. So I'm glad we're finally 9 00:00:33,159 --> 00:00:35,760 Speaker 1: coming around to it. I think I had some hesitation 10 00:00:35,840 --> 00:00:37,879 Speaker 1: for a while that I want to briefly explain right 11 00:00:37,920 --> 00:00:40,920 Speaker 1: at the beginning here. But today we're gonna be talking 12 00:00:40,960 --> 00:00:46,239 Speaker 1: about an idea known as the Silurian hypothesis. Uh. And 13 00:00:46,360 --> 00:00:49,280 Speaker 1: just to give you a little bit of background knowledge, 14 00:00:49,280 --> 00:00:52,560 Speaker 1: we spent several minutes before recording today trying to look 15 00:00:52,640 --> 00:00:56,280 Speaker 1: up how they pronounced Silurian on Doctor Who, because I 16 00:00:56,360 --> 00:00:58,680 Speaker 1: was like, sure they might use some kind of British 17 00:00:58,720 --> 00:01:03,720 Speaker 1: English variation where they a Silurian, but but a last 18 00:01:03,800 --> 00:01:06,280 Speaker 1: we could not ever get the doctor to say it right. 19 00:01:06,319 --> 00:01:08,959 Speaker 1: I watched I think an entire scene where one of 20 00:01:08,959 --> 00:01:12,640 Speaker 1: the more recent doctors was chatting with us Silurian or 21 00:01:12,800 --> 00:01:16,280 Speaker 1: Silurian out out of your will, and they they it 22 00:01:16,360 --> 00:01:17,800 Speaker 1: was like they were trying not to say it, like 23 00:01:17,840 --> 00:01:20,559 Speaker 1: if they said it, one would would pop up and 24 00:01:20,560 --> 00:01:23,080 Speaker 1: and crawl out of the screen or something they used 25 00:01:23,120 --> 00:01:25,800 Speaker 1: they referred to another alien race. There wasn't even in 26 00:01:25,840 --> 00:01:27,760 Speaker 1: the scene, and I don't even think was part of 27 00:01:27,760 --> 00:01:31,400 Speaker 1: that episode. And then in all these other terms. But yeah, 28 00:01:31,400 --> 00:01:33,760 Speaker 1: they were just trying to mess with me. So this 29 00:01:33,840 --> 00:01:36,800 Speaker 1: is a topic that I have been interested in covering 30 00:01:37,000 --> 00:01:39,760 Speaker 1: for quite a while. It's it's been a few years now, 31 00:01:40,120 --> 00:01:43,520 Speaker 1: But Rob, when you suggested it, I realized that I'd 32 00:01:43,560 --> 00:01:46,679 Speaker 1: always been hesitating and not wanting to quite go ahead 33 00:01:46,720 --> 00:01:49,240 Speaker 1: with it. And I think I realized the reason for that, 34 00:01:49,320 --> 00:01:52,640 Speaker 1: which is that when I saw people mentioning this paper 35 00:01:52,760 --> 00:01:55,480 Speaker 1: on the internet, it was clear to me that a 36 00:01:55,520 --> 00:01:59,400 Speaker 1: lot of them were getting exactly the wrong takeaway from it, 37 00:01:59,440 --> 00:02:02,560 Speaker 1: Like they were matching onto a very shallow understanding of 38 00:02:02,600 --> 00:02:06,080 Speaker 1: the concept and and running off in a in a 39 00:02:06,200 --> 00:02:09,480 Speaker 1: very different direction than the authors intended. Not only a 40 00:02:09,480 --> 00:02:13,000 Speaker 1: different direction than they intend, but a direction they specifically 41 00:02:13,080 --> 00:02:16,040 Speaker 1: say do not go in, and specifically say that they 42 00:02:16,040 --> 00:02:19,720 Speaker 1: are not trying to to make Yeah. Uh, so to 43 00:02:19,720 --> 00:02:23,120 Speaker 1: to clarify what we're talking about here. The Silurian Hypothesis 44 00:02:23,120 --> 00:02:27,080 Speaker 1: paper begins with a fascinating question, in the words of 45 00:02:27,120 --> 00:02:31,520 Speaker 1: the author's quote, if an industrial civilization had existed on 46 00:02:31,639 --> 00:02:35,480 Speaker 1: Earth many millions of years prior to our own era, 47 00:02:36,080 --> 00:02:38,840 Speaker 1: what traces would it have left and would they be 48 00:02:39,000 --> 00:02:42,440 Speaker 1: detectable today? That that's the question at the heart of 49 00:02:42,480 --> 00:02:46,480 Speaker 1: this paper. And obviously this is a tantalizing premise. You know, 50 00:02:46,480 --> 00:02:50,799 Speaker 1: it sets your mind racing with images of impossibly weird organisms, 51 00:02:50,800 --> 00:02:54,639 Speaker 1: you know, like land dwelling octopi and stuff in the 52 00:02:54,760 --> 00:02:57,160 Speaker 1: in their own weird cities, and and what kind of 53 00:02:57,160 --> 00:02:59,880 Speaker 1: technology would they have? Things that are as alien as 54 00:02:59,880 --> 00:03:03,760 Speaker 1: anything you could imagine on another planet, except they would 55 00:03:03,760 --> 00:03:07,960 Speaker 1: have all been from here, native to planet Earth, dating 56 00:03:08,000 --> 00:03:12,080 Speaker 1: back millions of years into prehistory. But while this is 57 00:03:12,120 --> 00:03:16,959 Speaker 1: a really attractive imaginative exercise, I think the first order 58 00:03:17,000 --> 00:03:19,200 Speaker 1: of business when talking about this subject is to be 59 00:03:19,240 --> 00:03:23,440 Speaker 1: clear that the Silurian Hypothesis paper is about coming up 60 00:03:23,480 --> 00:03:29,240 Speaker 1: with a framework for detecting physical traces of industrial civilizations 61 00:03:29,280 --> 00:03:33,160 Speaker 1: and understanding how long those traces last. So it's about 62 00:03:33,480 --> 00:03:36,000 Speaker 1: trying to say, what are the right questions to ask 63 00:03:36,080 --> 00:03:38,200 Speaker 1: when you're when you're looking at a planet and saying, 64 00:03:38,240 --> 00:03:40,680 Speaker 1: how could we tell if there had been a civilization 65 00:03:40,720 --> 00:03:43,040 Speaker 1: on this planet a long time ago? It is not 66 00:03:43,320 --> 00:03:46,760 Speaker 1: a paper arguing that there was in fact a lost 67 00:03:46,800 --> 00:03:51,080 Speaker 1: civilization deep in Earth's past. So it's not evidence for 68 00:03:51,160 --> 00:03:56,120 Speaker 1: lizard men, ancient aliens, Graham Hancock, junk Atlantis, or any 69 00:03:56,160 --> 00:03:59,120 Speaker 1: of that stuff. But I would say in its true form, 70 00:03:59,280 --> 00:04:04,040 Speaker 1: it is a really interesting question. Yeah, And at heart 71 00:04:04,120 --> 00:04:06,800 Speaker 1: this episode is is not going to be about scientific 72 00:04:06,840 --> 00:04:09,360 Speaker 1: evidence for lizard men civilizations in the Hollow Earth. So 73 00:04:09,400 --> 00:04:11,200 Speaker 1: if you're looking for that, this is this is not 74 00:04:11,240 --> 00:04:13,600 Speaker 1: the episode for you. But yeah, what I love about 75 00:04:13,640 --> 00:04:15,600 Speaker 1: it is that it takes this sort of fantastic idea 76 00:04:15,640 --> 00:04:19,560 Speaker 1: and then examines it reasonably, and that examination eliminates some 77 00:04:19,720 --> 00:04:25,919 Speaker 1: very interesting geologic, climatic, and astrophysical considerations, So you know, 78 00:04:25,960 --> 00:04:30,279 Speaker 1: setting aside pseudoscience and pseudo archaeology here. But on the 79 00:04:30,279 --> 00:04:32,960 Speaker 1: other hand, I think if you if you're looking for 80 00:04:33,000 --> 00:04:35,840 Speaker 1: some sci fi fund this topic in this episode will 81 00:04:35,880 --> 00:04:40,239 Speaker 1: also still engage you. Um, but it is interesting how 82 00:04:40,960 --> 00:04:43,320 Speaker 1: from a certain perspective you can imagine people being drawn 83 00:04:43,360 --> 00:04:45,640 Speaker 1: into it by just sort of this sci fi idea, 84 00:04:46,120 --> 00:04:49,440 Speaker 1: this idea that does lean lend itself well to sort 85 00:04:49,440 --> 00:04:53,800 Speaker 1: of conspiracy theorist mindsets, and then realizing, actually, this paper 86 00:04:54,000 --> 00:04:58,440 Speaker 1: is about geology and UH and U and the last 87 00:04:58,520 --> 00:05:01,560 Speaker 1: year of our planet and also, oh, I guess kind 88 00:05:01,560 --> 00:05:03,560 Speaker 1: of you know, in many cases, kind of a downbeat 89 00:05:03,920 --> 00:05:09,760 Speaker 1: message about the lasting impact of human technology on our planet. 90 00:05:10,240 --> 00:05:13,039 Speaker 1: And on the other hand, too, how forgettable we may 91 00:05:13,040 --> 00:05:17,840 Speaker 1: be from the standpoint of geological history. Yeah, so if 92 00:05:17,839 --> 00:05:19,919 Speaker 1: you're on board for all of that, you've come to 93 00:05:19,960 --> 00:05:23,200 Speaker 1: the right place. So real quick, I do want to 94 00:05:23,240 --> 00:05:27,960 Speaker 1: just discuss the Doctor Who reference here, since since uh, 95 00:05:28,080 --> 00:05:31,280 Speaker 1: the authors Schmidt and Frank took the name for the 96 00:05:31,360 --> 00:05:35,360 Speaker 1: hypothesis from the Doctor Who species the Silurians, who first 97 00:05:35,400 --> 00:05:39,120 Speaker 1: popped up in the nineteen seventies series Doctor Who. And 98 00:05:39,279 --> 00:05:42,479 Speaker 1: these Silurians, I think, now you've got me saying silurians, 99 00:05:43,400 --> 00:05:47,200 Speaker 1: I probably probably stuff this way. Well, it gets even 100 00:05:47,240 --> 00:05:50,520 Speaker 1: worse because so they take the name of the hypothesis 101 00:05:50,560 --> 00:05:53,680 Speaker 1: from this Doctor Who series where these creatures show up. 102 00:05:54,080 --> 00:05:56,200 Speaker 1: But then they say explicitly in the paper, you know, 103 00:05:56,279 --> 00:05:58,880 Speaker 1: the range we would really be looking at would actually 104 00:05:58,880 --> 00:06:03,400 Speaker 1: be after the Lurian geologic period, the Silurian period is 105 00:06:03,440 --> 00:06:07,240 Speaker 1: something that's like a roughly twenty million year period that's 106 00:06:07,279 --> 00:06:09,440 Speaker 1: more than four hundred million years ago. I don't remember. 107 00:06:09,440 --> 00:06:12,080 Speaker 1: It's like four hundred and forty something to four hundred 108 00:06:12,080 --> 00:06:15,200 Speaker 1: and twenty something, I think roughly. But if you were 109 00:06:15,240 --> 00:06:19,520 Speaker 1: seriously looking for evidence of lost civilizations in Earth's ancient past, 110 00:06:20,000 --> 00:06:22,840 Speaker 1: you'd probably be looking for things like after about four 111 00:06:22,920 --> 00:06:25,560 Speaker 1: hundred million years ago, coming you know, forward in time 112 00:06:25,600 --> 00:06:29,240 Speaker 1: from the Devonian period, when you could have the reasonable 113 00:06:29,240 --> 00:06:32,599 Speaker 1: biological basis for land dwelling animals that might have evolved 114 00:06:32,640 --> 00:06:38,520 Speaker 1: complex technological intelligence. Yes, but any rate. In Doctor Who, 115 00:06:39,279 --> 00:06:44,520 Speaker 1: especially in that original nineteen seventy uh appearance, the Silurians 116 00:06:44,560 --> 00:06:47,640 Speaker 1: are these kind of lizard men um. They factor into 117 00:06:47,680 --> 00:06:50,599 Speaker 1: this plot with the third Doctor played by John part 118 00:06:50,680 --> 00:06:53,840 Speaker 1: Way Who nineteen nine, nine ninety six, and then they 119 00:06:53,880 --> 00:06:57,360 Speaker 1: subsequently pop up again with the fifth Doctor played by 120 00:06:57,360 --> 00:07:00,400 Speaker 1: Peter Davison and the eleventh Doctor played by Matt Smith, 121 00:07:00,839 --> 00:07:03,520 Speaker 1: and then more recently the third teenth Doctor played by 122 00:07:03,600 --> 00:07:06,240 Speaker 1: Jody Whittaker. So this is just the TV show. I 123 00:07:06,240 --> 00:07:08,520 Speaker 1: can't speak to the various books and audio dramas that 124 00:07:08,560 --> 00:07:12,040 Speaker 1: have come out, and their look has changed throughout the film. Um, 125 00:07:12,120 --> 00:07:15,120 Speaker 1: you know, they are, in essence, this cold blooded, prehistoric 126 00:07:15,200 --> 00:07:20,280 Speaker 1: reptile like species with significant technological advancement that they they 127 00:07:20,320 --> 00:07:22,920 Speaker 1: I think they end up entering various states of suspended 128 00:07:22,960 --> 00:07:26,280 Speaker 1: animation to avoid uh you know, major changes on Earth, 129 00:07:26,360 --> 00:07:29,560 Speaker 1: changes to the climate, etcetera. Um, and then they re 130 00:07:29,680 --> 00:07:34,840 Speaker 1: emerge and encounter the Doctor. Um. So yeah, they're They're 131 00:07:34,880 --> 00:07:39,480 Speaker 1: one of the many interesting alien and otherworldly species that 132 00:07:39,600 --> 00:07:42,960 Speaker 1: pop up. Uh. Though, I guess with the Silurians, one 133 00:07:42,960 --> 00:07:46,000 Speaker 1: of the key things is that they're they're not pure aliens. 134 00:07:46,040 --> 00:07:49,760 Speaker 1: They're they're sort of the originals. There are their original terrans, 135 00:07:49,800 --> 00:07:54,360 Speaker 1: original earthlings, uh, that are then encountered by these evolved 136 00:07:54,400 --> 00:07:57,200 Speaker 1: apes that come much later. I mean to to them, 137 00:07:57,280 --> 00:08:02,320 Speaker 1: we are the aliens. Yeah right, we're these weird future creatures. Uh. 138 00:08:02,480 --> 00:08:05,480 Speaker 1: The image would tend And I gotta be honest, I'm 139 00:08:05,480 --> 00:08:08,680 Speaker 1: not a hoovoid, so I don't know the lore. But 140 00:08:09,560 --> 00:08:12,160 Speaker 1: the picture you're showing me of the Silurians, they look 141 00:08:12,240 --> 00:08:16,560 Speaker 1: like they look like if the world was all creature 142 00:08:16,640 --> 00:08:20,240 Speaker 1: from the Black Lagoon and there was a leather face 143 00:08:20,600 --> 00:08:24,960 Speaker 1: of the creature from the Black Lagoon civilization. Yeah, I 144 00:08:24,960 --> 00:08:27,480 Speaker 1: mean they're definitely Doctor Who creatures of this era, which 145 00:08:27,600 --> 00:08:30,040 Speaker 1: which I tend to love these costumes. I know they 146 00:08:30,080 --> 00:08:34,360 Speaker 1: were working with with with with budget limitations here, but yeah, 147 00:08:34,360 --> 00:08:37,400 Speaker 1: the the aliens and robots of this era really really 148 00:08:37,440 --> 00:08:40,360 Speaker 1: called me. Now you said you look kind of fish like. 149 00:08:40,559 --> 00:08:42,920 Speaker 1: Bear in mind, and I'm sure some Doctor Who listeners 150 00:08:43,320 --> 00:08:45,720 Speaker 1: Doctor Who viewers will will will chime in here, But 151 00:08:45,760 --> 00:08:49,040 Speaker 1: I believe they are related to another species that pops 152 00:08:49,080 --> 00:08:50,760 Speaker 1: up on the show that live in the water. I 153 00:08:50,760 --> 00:08:53,960 Speaker 1: think they're like the sea devils or something. Um, but 154 00:08:54,200 --> 00:08:57,000 Speaker 1: these guys are not aquatic in nature. I think I 155 00:08:57,040 --> 00:08:59,120 Speaker 1: got that right. The seed of Oh wait, this is 156 00:08:59,160 --> 00:09:02,800 Speaker 1: that like a a bunch of intelligent euryptorids or something 157 00:09:03,960 --> 00:09:06,880 Speaker 1: something like that. Yeah, alright, So this is two thousand 158 00:09:06,960 --> 00:09:10,920 Speaker 1: eighteen paper the Silurian hypothesis, Would it be possible to 159 00:09:10,960 --> 00:09:15,000 Speaker 1: detect an industrial civilization in the Geological Record? This was 160 00:09:15,040 --> 00:09:20,080 Speaker 1: published in the journal International Journal of Astrobiology. UH. It 161 00:09:20,160 --> 00:09:23,320 Speaker 1: draws its name from that Doctor Who episode, and the 162 00:09:23,360 --> 00:09:25,319 Speaker 1: authors here that they point out that they may be 163 00:09:25,440 --> 00:09:29,599 Speaker 1: the first to seriously consider whether a technologically advanced civilization 164 00:09:29,679 --> 00:09:32,560 Speaker 1: could have evolved prior to Homo sapiens on Earth, though 165 00:09:32,600 --> 00:09:35,320 Speaker 1: the authors due stress that this is a to the 166 00:09:35,360 --> 00:09:38,320 Speaker 1: best of their knowledge situation, so you know, it's entirely 167 00:09:38,320 --> 00:09:42,120 Speaker 1: possible somebody was batting around the idea previously, but this 168 00:09:42,200 --> 00:09:44,120 Speaker 1: may be the first, and certainly this was. This one 169 00:09:44,160 --> 00:09:46,320 Speaker 1: really made a splash when it came out. Okay, So 170 00:09:46,440 --> 00:09:50,200 Speaker 1: the two authors here would be Adam Frank and Givin A. 171 00:09:50,400 --> 00:09:54,280 Speaker 1: Schmidt right and Frank is a is a physicist and astronomer, 172 00:09:54,320 --> 00:09:58,240 Speaker 1: and Schmidt is a climate scientist right right. Schmidt is 173 00:09:58,280 --> 00:10:01,720 Speaker 1: a climatologist, climate model and director of the NASA Gotted 174 00:10:01,800 --> 00:10:04,559 Speaker 1: Institute for Space Studies in New York and co founder 175 00:10:04,559 --> 00:10:08,040 Speaker 1: of the award winning climate science blog Real Climate. Frank 176 00:10:08,200 --> 00:10:11,160 Speaker 1: is a physicist, astronomer, and writer whose work has appeared 177 00:10:11,200 --> 00:10:13,400 Speaker 1: in such publications as The New York Times and NPR, 178 00:10:13,679 --> 00:10:15,520 Speaker 1: and I believe we've actually referenced his work on the 179 00:10:15,559 --> 00:10:19,040 Speaker 1: podcast before. Uh. He also has a book. He has 180 00:10:19,040 --> 00:10:21,960 Speaker 1: a few books, including The Constant Fire, The End of 181 00:10:21,960 --> 00:10:24,880 Speaker 1: the Beginning, and Light of the Stars. Those are all 182 00:10:25,000 --> 00:10:28,040 Speaker 1: nonfiction science books, of course, So to be clear, we're 183 00:10:28,040 --> 00:10:32,160 Speaker 1: talking about two very legitimate scientists and science communicators, not 184 00:10:32,679 --> 00:10:35,400 Speaker 1: you know, not a couple of of quacks who were 185 00:10:35,440 --> 00:10:38,320 Speaker 1: staring into the hollow Earth or anything. So the authors 186 00:10:38,360 --> 00:10:41,680 Speaker 1: here begin with a very reasonable consideration of the search 187 00:10:41,720 --> 00:10:44,800 Speaker 1: for intelligent life elsewhere in the universe. Uh. And then 188 00:10:44,840 --> 00:10:46,720 Speaker 1: this is something we've we've touched on the show plenty 189 00:10:46,720 --> 00:10:49,480 Speaker 1: of times before. Ours is the only model of life, 190 00:10:49,880 --> 00:10:53,160 Speaker 1: but we generally consider technological advancement to be a hallmark 191 00:10:53,280 --> 00:10:55,600 Speaker 1: of intelligent life. And more to the point, something we 192 00:10:55,640 --> 00:10:59,079 Speaker 1: can search for signs of, uh concerning other worlds and 193 00:10:59,120 --> 00:11:02,280 Speaker 1: other star systems. Uh. You know, and anytime you can, 194 00:11:02,360 --> 00:11:04,920 Speaker 1: you can figure out how to look for signs of 195 00:11:04,920 --> 00:11:09,400 Speaker 1: of advanced and expansive energy harvesting or consumption. Uh. That 196 00:11:09,520 --> 00:11:11,280 Speaker 1: might be a way for us to tell if there's 197 00:11:11,320 --> 00:11:15,400 Speaker 1: something else out there that is significantly advanced. Right, and 198 00:11:15,480 --> 00:11:20,880 Speaker 1: it also might be a simple prerequisite for contact, because uh, 199 00:11:21,160 --> 00:11:24,040 Speaker 1: they're talking about so that they started off by looking 200 00:11:24,080 --> 00:11:26,679 Speaker 1: at this as an astrobiology question. You know, you're you're 201 00:11:26,720 --> 00:11:29,640 Speaker 1: looking for signs of life elsewhere in the universe. And 202 00:11:29,679 --> 00:11:31,880 Speaker 1: of course, the the search for intelligent life in the 203 00:11:31,960 --> 00:11:35,280 Speaker 1: universe in practical terms, what's accessible to us really boils 204 00:11:35,320 --> 00:11:39,320 Speaker 1: down to the search for life capable of Harvard harnessing 205 00:11:39,440 --> 00:11:42,360 Speaker 1: radio technology within our galaxy. You know, you could probably 206 00:11:42,400 --> 00:11:48,000 Speaker 1: find maybe chemical biosignatures in in the atmospheres of exoplanets 207 00:11:48,080 --> 00:11:50,360 Speaker 1: that would give you an indication that there's some kind 208 00:11:50,360 --> 00:11:53,480 Speaker 1: of life there, maybe bacterial in nature or whatever. But 209 00:11:53,520 --> 00:11:56,280 Speaker 1: if you're looking for intelligent life, you're you're probably talking 210 00:11:56,280 --> 00:11:59,640 Speaker 1: about radio of some kind, right, And so the kinds 211 00:11:59,679 --> 00:12:04,120 Speaker 1: of civilizations that develop radio communication technology would fall under 212 00:12:04,160 --> 00:12:08,040 Speaker 1: the classification of industrial civilizations. And these are what author 213 00:12:08,320 --> 00:12:11,520 Speaker 1: the authors define as civilizations that have the ability to 214 00:12:11,640 --> 00:12:15,560 Speaker 1: harness energy on a global scale. And they bring up 215 00:12:15,559 --> 00:12:18,760 Speaker 1: how this actually feeds into one of the the recurring 216 00:12:19,440 --> 00:12:25,040 Speaker 1: characters in in the astrobiology literature, the Drake equation. That's right, Yeah, 217 00:12:24,520 --> 00:12:27,800 Speaker 1: they bust out the Drake equation, and of course consider 218 00:12:27,840 --> 00:12:30,360 Speaker 1: how how some of the takeaways relate to Earth, especially 219 00:12:30,400 --> 00:12:33,000 Speaker 1: the notion that over the course of a planet's existence, 220 00:12:33,440 --> 00:12:37,480 Speaker 1: multiple industrial civilizations can theoretically arise over the span of 221 00:12:37,559 --> 00:12:40,840 Speaker 1: time that life exists there. And then we have to 222 00:12:40,880 --> 00:12:43,400 Speaker 1: factor in questions over you know, how many times life 223 00:12:43,440 --> 00:12:46,240 Speaker 1: itself may have evolved or started out on Earth before 224 00:12:46,280 --> 00:12:50,000 Speaker 1: our last universal common ancestors got going. The possibility of 225 00:12:50,000 --> 00:12:53,239 Speaker 1: a shadow biosphere and the idea that species like dolphins 226 00:12:53,600 --> 00:12:57,600 Speaker 1: may suggest independent evolutions of intelligence on Earth. Um, you know, 227 00:12:57,600 --> 00:13:00,480 Speaker 1: so we're left with this idea that, yeah, the radically 228 00:13:00,720 --> 00:13:04,520 Speaker 1: and given the footprint of life on Earth, you could 229 00:13:04,640 --> 00:13:08,760 Speaker 1: have had multiple intelligences uh evolved and arise during that 230 00:13:08,840 --> 00:13:12,679 Speaker 1: time period. Because that's certainly what the Drake equation seems 231 00:13:12,720 --> 00:13:15,600 Speaker 1: to allow for concerning other worlds. Well, yeah, and I 232 00:13:15,840 --> 00:13:18,640 Speaker 1: you know so I kind of love the Drake equation. 233 00:13:18,840 --> 00:13:20,880 Speaker 1: You know, it's a famous tool that I really enjoy 234 00:13:21,000 --> 00:13:25,760 Speaker 1: thinking about because because it does the job of taking 235 00:13:25,800 --> 00:13:29,240 Speaker 1: a question that seems like we could not possibly answer. 236 00:13:29,360 --> 00:13:33,360 Speaker 1: The question is how many active technological civilizations are there 237 00:13:33,360 --> 00:13:36,080 Speaker 1: in the Milky Way galaxy? And you know, if you're 238 00:13:36,200 --> 00:13:38,720 Speaker 1: being honest with yourself, the correct answer to that is 239 00:13:38,880 --> 00:13:41,240 Speaker 1: how the hell should I know? Like, there's no way 240 00:13:41,280 --> 00:13:44,720 Speaker 1: to answer that question at all. But what the Drake 241 00:13:44,760 --> 00:13:49,720 Speaker 1: equation does is break that unanswerable question down into a 242 00:13:49,880 --> 00:13:53,800 Speaker 1: number of other questions that you then multiplied together to 243 00:13:53,960 --> 00:13:58,040 Speaker 1: get an estimated number. And many of those smaller questions 244 00:13:58,120 --> 00:14:01,280 Speaker 1: themselves could perhaps be answered, and in fact, some of 245 00:14:01,320 --> 00:14:04,640 Speaker 1: them have been answered since the Drake equation was first formulated. 246 00:14:05,240 --> 00:14:09,280 Speaker 1: Uh so, So it decomposes an unsolvable problem of are 247 00:14:09,320 --> 00:14:11,880 Speaker 1: there aliens out there? And if so, how many, into 248 00:14:11,920 --> 00:14:14,680 Speaker 1: a series of smaller problems, at least some of which 249 00:14:14,720 --> 00:14:16,960 Speaker 1: are solvable, maybe all of which are. You know, you 250 00:14:16,960 --> 00:14:19,200 Speaker 1: could come up with some kind of reasonable gas about. 251 00:14:20,040 --> 00:14:22,400 Speaker 1: And so the classic formulation of the Drake equation is 252 00:14:22,440 --> 00:14:25,280 Speaker 1: to get your number of civilizations in the milky way, 253 00:14:25,840 --> 00:14:28,360 Speaker 1: you would multiply a bunch of different terms together. So 254 00:14:28,480 --> 00:14:31,680 Speaker 1: one is the rate of average the average rate of 255 00:14:31,720 --> 00:14:34,440 Speaker 1: star formation. You know, how much do you get stars 256 00:14:34,960 --> 00:14:39,400 Speaker 1: times the fraction of stars that have planets times the 257 00:14:39,440 --> 00:14:43,520 Speaker 1: average number of planets per star, times the fraction of 258 00:14:43,560 --> 00:14:47,720 Speaker 1: planets that develop life times the portion of those life 259 00:14:47,760 --> 00:14:51,840 Speaker 1: systems that gain intelligence, times the portion of those intelligent 260 00:14:51,920 --> 00:14:56,040 Speaker 1: life systems that develop technological means to communicate times. And 261 00:14:56,080 --> 00:14:59,400 Speaker 1: then here's a really interesting term, quote the length of 262 00:14:59,480 --> 00:15:04,200 Speaker 1: time l over which such civilizations released detectable signals. And 263 00:15:04,240 --> 00:15:06,840 Speaker 1: it's this very last term that I think very often 264 00:15:06,880 --> 00:15:09,440 Speaker 1: gets overlooked by people who are thinking about, you know, 265 00:15:09,480 --> 00:15:12,080 Speaker 1: are there aliens out there? And how could we know? 266 00:15:12,800 --> 00:15:14,880 Speaker 1: I think we often tend to assume that, well, once 267 00:15:14,960 --> 00:15:18,600 Speaker 1: there are aliens with technological means to communicate. That's just 268 00:15:18,640 --> 00:15:22,800 Speaker 1: like a you know, progress only extends from their civilizations 269 00:15:22,880 --> 00:15:25,840 Speaker 1: just continue to get bigger and their capabilities expand and 270 00:15:25,840 --> 00:15:28,320 Speaker 1: they spread out from there. But I don't know that 271 00:15:28,720 --> 00:15:32,440 Speaker 1: there could be severe limitations on the length of a 272 00:15:32,680 --> 00:15:37,720 Speaker 1: radio receptive or radio broadcasting civilization. Maybe they only exist 273 00:15:37,760 --> 00:15:39,840 Speaker 1: for a few hundred years. Because one thing we know 274 00:15:39,920 --> 00:15:45,480 Speaker 1: is that our technological civilization is just a tiny blip 275 00:15:45,720 --> 00:15:48,280 Speaker 1: on the history of planet Earth, even a tiny blip 276 00:15:48,360 --> 00:15:50,960 Speaker 1: on the history of life on planet Earth. Earth is 277 00:15:51,280 --> 00:15:54,160 Speaker 1: four point five billion years old. There's been life on 278 00:15:54,200 --> 00:15:57,160 Speaker 1: Earth for most of that time. Uh. The authors here 279 00:15:57,240 --> 00:15:59,880 Speaker 1: estimate that there has been complex life on Earth to 280 00:16:00,120 --> 00:16:04,320 Speaker 1: land surface for only about four hundred million years. So 281 00:16:04,440 --> 00:16:06,960 Speaker 1: that's only a fraction of the entire history of Earth. 282 00:16:07,200 --> 00:16:09,160 Speaker 1: But that but four hundred million years is still a 283 00:16:09,160 --> 00:16:12,560 Speaker 1: gargantuan amount of time compared to the length of human civilization. 284 00:16:13,040 --> 00:16:16,400 Speaker 1: They say, industrial civilization, you know, by their metric, has 285 00:16:16,440 --> 00:16:19,360 Speaker 1: probably existed for only about three hundred years. This is 286 00:16:19,560 --> 00:16:23,880 Speaker 1: since roughly the beginning of mass production methods for for things, 287 00:16:24,320 --> 00:16:26,680 Speaker 1: and so if humans were wiped out by a global 288 00:16:26,760 --> 00:16:29,680 Speaker 1: mass extinction, of some kind in the near future. Our 289 00:16:29,720 --> 00:16:34,360 Speaker 1: industrial civilization would just be this tiny little splinter, this 290 00:16:34,640 --> 00:16:38,240 Speaker 1: blip of three hundred years on a history of a 291 00:16:38,320 --> 00:16:42,280 Speaker 1: currently four point five billion year old planet. Yeah, and 292 00:16:42,360 --> 00:16:45,200 Speaker 1: so from there we get into the question, Okay, if 293 00:16:45,240 --> 00:16:47,600 Speaker 1: if you have an industrial civilization like this, it is 294 00:16:47,640 --> 00:16:50,880 Speaker 1: just a blip, would we be able to see it? 295 00:16:51,280 --> 00:16:53,520 Speaker 1: And if we could see it, what would we look for? 296 00:16:53,600 --> 00:16:55,000 Speaker 1: And this is you know, this is pretty much the 297 00:16:55,320 --> 00:16:58,720 Speaker 1: meat of the paper here analyzing this sort of question, 298 00:16:58,760 --> 00:17:00,800 Speaker 1: which which is great because it it again it gets 299 00:17:00,800 --> 00:17:04,440 Speaker 1: into sort of uh, you know, sci fi friendly concepts. 300 00:17:04,800 --> 00:17:08,359 Speaker 1: It's a useful in considering the evolution of life and 301 00:17:08,400 --> 00:17:11,879 Speaker 1: the existence of intelligent life on other worlds. And it 302 00:17:11,960 --> 00:17:15,440 Speaker 1: also shines a light on what we're doing now and 303 00:17:15,520 --> 00:17:19,000 Speaker 1: where we are. And and I think also, uh, you know, 304 00:17:19,080 --> 00:17:24,280 Speaker 1: illustrates nicely illustrates this idea that um that that the 305 00:17:24,320 --> 00:17:27,679 Speaker 1: technology is not just this um that this this this 306 00:17:27,840 --> 00:17:30,280 Speaker 1: ramp to Star Trek, you know, or this ramp to 307 00:17:30,440 --> 00:17:32,960 Speaker 1: the culture or any of our more optimistic sci fi 308 00:17:33,040 --> 00:17:36,639 Speaker 1: dreams like there are there are severe challenges. Uh. And 309 00:17:36,680 --> 00:17:40,000 Speaker 1: of course there's there's always the risk of extinction. That's 310 00:17:40,000 --> 00:17:43,600 Speaker 1: exactly right. And one thing that's funny is we don't 311 00:17:43,800 --> 00:17:49,919 Speaker 1: know whether the rise of technological civilization should generally be 312 00:17:50,000 --> 00:17:53,520 Speaker 1: understood as, on average, a linear process where it just 313 00:17:53,560 --> 00:17:56,199 Speaker 1: sort of goes in one direction and keeps going in 314 00:17:56,240 --> 00:17:59,240 Speaker 1: that direction, or whether it should be understood as on 315 00:17:59,320 --> 00:18:02,440 Speaker 1: average a sick clickal process where you get a rise 316 00:18:02,440 --> 00:18:05,840 Speaker 1: in technological civilization, then then it disappears for some reason. 317 00:18:05,880 --> 00:18:08,760 Speaker 1: You can imagine what some of those reasons might be. Um, 318 00:18:09,040 --> 00:18:11,679 Speaker 1: and uh, and then maybe rises again out of the 319 00:18:11,720 --> 00:18:14,399 Speaker 1: out of the same biosphere. I mean, either one I 320 00:18:14,440 --> 00:18:18,320 Speaker 1: think is a perfectly plausible model to entertain is like 321 00:18:18,400 --> 00:18:22,199 Speaker 1: what usually happens in the universe. Uh. And we just 322 00:18:22,240 --> 00:18:24,919 Speaker 1: don't have the h we don't have the evidence to 323 00:18:24,960 --> 00:18:27,399 Speaker 1: really have an opinion on that. Yeah, I mean a 324 00:18:27,440 --> 00:18:30,600 Speaker 1: lot of it just comes back to the fact that, again, 325 00:18:30,680 --> 00:18:34,000 Speaker 1: we are the only model of intelligent life, and certainly 326 00:18:34,040 --> 00:18:38,080 Speaker 1: technologically advanced intelligent life that we have to look at, 327 00:18:38,480 --> 00:18:40,679 Speaker 1: So we have nothing to compare us to. Yeah, and 328 00:18:40,720 --> 00:18:42,520 Speaker 1: we don't know what's going to happen to us in 329 00:18:42,560 --> 00:18:47,240 Speaker 1: the long run. Right. So uh, Well, let's get into 330 00:18:47,280 --> 00:18:48,760 Speaker 1: the I guess the sort of the first part of 331 00:18:48,760 --> 00:18:50,520 Speaker 1: the paper, and I do want to drive home that 332 00:18:50,560 --> 00:18:53,159 Speaker 1: if you want to just go right to the paper 333 00:18:53,280 --> 00:18:56,119 Speaker 1: yourself and dive in. Um, you just do a search 334 00:18:56,160 --> 00:18:59,000 Speaker 1: for the title and you can find it hosted on NASA. 335 00:18:59,080 --> 00:19:01,840 Speaker 1: They have as has a as a PDF of this 336 00:19:02,000 --> 00:19:05,439 Speaker 1: that's very easily accessible. Uh. You can also read it 337 00:19:05,480 --> 00:19:08,040 Speaker 1: in full on the Cambridge University Press website, which I 338 00:19:08,040 --> 00:19:11,240 Speaker 1: think is the press behind the journal, the International Journal 339 00:19:11,359 --> 00:19:13,880 Speaker 1: Journal of Astrobiology. And yeah, so it's all on their 340 00:19:13,960 --> 00:19:16,120 Speaker 1: end with the references hyper linked and all that, which 341 00:19:16,160 --> 00:19:18,760 Speaker 1: is nice. Yes, yeah, absolutely so if he hit a paywall, 342 00:19:18,880 --> 00:19:21,560 Speaker 1: don't don't give up. It's out there. UM. And I 343 00:19:21,560 --> 00:19:23,560 Speaker 1: believe Adam Frank also wrote a piece for What the 344 00:19:23,560 --> 00:19:26,880 Speaker 1: Atlantic where he nicely summarizes some of the ideas here. 345 00:19:27,040 --> 00:19:29,240 Speaker 1: Oh yeah, and he also tells a funny story about 346 00:19:29,240 --> 00:19:31,639 Speaker 1: how they arrived at writing the paper, because I think 347 00:19:31,720 --> 00:19:35,080 Speaker 1: he says, uh, he showed up in Gevin Schmidt's office 348 00:19:35,160 --> 00:19:39,240 Speaker 1: to to talk about UM, to talk more about astrobiology 349 00:19:39,320 --> 00:19:42,480 Speaker 1: like Drake equation type questions, and he's like, okay, so 350 00:19:42,600 --> 00:19:46,639 Speaker 1: we we we know we've got one industrial civilization on Earth. 351 00:19:47,040 --> 00:19:49,359 Speaker 1: And then Schmidt responded by saying, how do we know 352 00:19:49,400 --> 00:19:53,359 Speaker 1: we're the only one just hitting that early like wall. 353 00:19:53,400 --> 00:19:56,400 Speaker 1: They're like wow, And then that turned into the paper. Yeah, 354 00:19:56,440 --> 00:20:04,760 Speaker 1: and it's it's it's quite a paper. So let's see, 355 00:20:04,880 --> 00:20:06,480 Speaker 1: let's get into the first part of it, which I 356 00:20:06,560 --> 00:20:08,320 Speaker 1: think you can loosely think of it's just sort of 357 00:20:08,320 --> 00:20:10,960 Speaker 1: a look at the limits of our vision. So they 358 00:20:11,000 --> 00:20:15,200 Speaker 1: point out that for the last two point five million years, uh, 359 00:20:15,240 --> 00:20:19,800 Speaker 1: there's widespread physical evidence of things like climate change, soil 360 00:20:19,880 --> 00:20:23,240 Speaker 1: horizons this is where one layer of soil differs from 361 00:20:23,280 --> 00:20:27,880 Speaker 1: belower above, speaking to changes recorded in the soil, as 362 00:20:27,880 --> 00:20:32,800 Speaker 1: well as archaeological evidence of non Homo sapiens cultures such 363 00:20:32,800 --> 00:20:36,400 Speaker 1: as the Neanderthals. And this two point five million year 364 00:20:36,480 --> 00:20:39,760 Speaker 1: period is known as the Quaternary. Now, going back before 365 00:20:39,800 --> 00:20:43,400 Speaker 1: the Quaternary again more than two point five million years ago, 366 00:20:43,640 --> 00:20:46,159 Speaker 1: the land evidence is harder to come by. You have 367 00:20:46,240 --> 00:20:50,639 Speaker 1: to depend on drilling, mining, and occasional exposed sections of 368 00:20:50,720 --> 00:20:54,320 Speaker 1: the earth. Even in the ocean, sentiment evidence apparently only 369 00:20:54,359 --> 00:20:57,840 Speaker 1: goes back to around one seventy million years ago. Yeah, 370 00:20:57,920 --> 00:21:00,119 Speaker 1: and I think for me this was actually one of 371 00:21:00,160 --> 00:21:04,040 Speaker 1: the most interesting parts of the paper because I would say, 372 00:21:04,080 --> 00:21:07,880 Speaker 1: if you just go by standard intuition. A person might think, uh, 373 00:21:07,960 --> 00:21:12,240 Speaker 1: you know, if there had been a civilization on Earth, 374 00:21:12,520 --> 00:21:15,600 Speaker 1: you know, a two million years ago or something like that. Uh, 375 00:21:15,760 --> 00:21:18,520 Speaker 1: would wouldn't that just be completely obvious, Like we'd see 376 00:21:18,520 --> 00:21:21,000 Speaker 1: evidence of it all around us? Would there be ruins 377 00:21:21,040 --> 00:21:23,399 Speaker 1: and all that, you know, their their stone hinges, their 378 00:21:23,440 --> 00:21:28,400 Speaker 1: skyscrapers and everything like that. Actually it's not. It might 379 00:21:28,440 --> 00:21:30,879 Speaker 1: not be as obvious as you might think. In fact, 380 00:21:31,119 --> 00:21:34,359 Speaker 1: the evidence of it could be rather scarce. And this 381 00:21:34,480 --> 00:21:38,399 Speaker 1: runs counter to our sci fi imaginings, right, because you 382 00:21:38,480 --> 00:21:42,480 Speaker 1: encounter elder civilizations and in other works like there's usually 383 00:21:42,480 --> 00:21:44,720 Speaker 1: some sort of a ruin or a vault or some 384 00:21:44,800 --> 00:21:48,560 Speaker 1: sort of mysterious monolith or something like the idea that 385 00:21:48,640 --> 00:21:52,080 Speaker 1: the elders would just be gone entirely, like just erased, 386 00:21:52,359 --> 00:21:55,119 Speaker 1: not by some sort of a conspiracy or by some 387 00:21:55,240 --> 00:21:58,200 Speaker 1: sort of a you know, alien shenanigans, but just because 388 00:21:58,240 --> 00:22:01,200 Speaker 1: things don't last that long. That's uh, it's an alien 389 00:22:01,240 --> 00:22:03,879 Speaker 1: concept from too many of our again, too many of 390 00:22:03,880 --> 00:22:06,480 Speaker 1: our creative visions of of what the future. In the past, 391 00:22:06,600 --> 00:22:09,159 Speaker 1: maybe exactly so, we think, well, you know, there are 392 00:22:09,240 --> 00:22:12,160 Speaker 1: ruins of civilizations from thousands of years ago, but that's 393 00:22:12,200 --> 00:22:15,800 Speaker 1: thousands of years ago. That's nothing in geological time. The 394 00:22:15,880 --> 00:22:18,040 Speaker 1: surface of the I mean, look a look at what 395 00:22:18,119 --> 00:22:21,800 Speaker 1: a map of the land formations on Earth just you know, 396 00:22:22,160 --> 00:22:25,000 Speaker 1: sixty million years ago looked like It's like, you know, 397 00:22:25,119 --> 00:22:28,600 Speaker 1: the the surface of the Earth is not fixed and constant. 398 00:22:28,640 --> 00:22:31,800 Speaker 1: This is a geologically active planet. So would there be 399 00:22:31,920 --> 00:22:35,159 Speaker 1: ruins all around us? Would evidence of a civilization from 400 00:22:35,280 --> 00:22:37,880 Speaker 1: hundreds of millions of years ago just be totally obvious? 401 00:22:38,560 --> 00:22:41,479 Speaker 1: I think I probably by the answer that the authors 402 00:22:41,520 --> 00:22:43,640 Speaker 1: give here, which is that no, it would probably not 403 00:22:43,720 --> 00:22:46,720 Speaker 1: be totally obvious. In fact, it might be incredibly difficult 404 00:22:46,760 --> 00:22:50,320 Speaker 1: to find evidence of at all. Uh. And so one 405 00:22:50,359 --> 00:22:52,760 Speaker 1: of the the interesting points the authors make here is 406 00:22:52,800 --> 00:22:55,880 Speaker 1: that the the exposed land surface of Earth, of course, 407 00:22:55,960 --> 00:22:59,280 Speaker 1: is geologically very young on average. They cite evidence from 408 00:22:59,280 --> 00:23:01,000 Speaker 1: a study by ma at mon at All in two 409 00:23:01,040 --> 00:23:04,360 Speaker 1: thousand nine that the oldest large patch of land surface 410 00:23:04,440 --> 00:23:08,000 Speaker 1: on Earth is probably in the Negev Desert, and that's 411 00:23:08,000 --> 00:23:10,600 Speaker 1: only about one point eight million years old. One point 412 00:23:10,680 --> 00:23:12,639 Speaker 1: eight million years, I mean, compared to the history of 413 00:23:12,680 --> 00:23:16,480 Speaker 1: civilization is a long time. But that's again, it's like 414 00:23:16,560 --> 00:23:19,560 Speaker 1: nothing in geological time. It's a tiny fraction of of 415 00:23:19,640 --> 00:23:23,040 Speaker 1: earth history. So if we wanted to find remnants of 416 00:23:23,040 --> 00:23:26,920 Speaker 1: a civilization from say, hundreds of millions of years ago, 417 00:23:27,359 --> 00:23:29,240 Speaker 1: you probably would not find that on the surface of 418 00:23:29,240 --> 00:23:31,320 Speaker 1: the Earth. You'd have to look for it in in 419 00:23:31,480 --> 00:23:36,560 Speaker 1: exposed geological strata from from previous eras. And even then 420 00:23:36,680 --> 00:23:38,520 Speaker 1: you can't just count on the fact that you would 421 00:23:38,520 --> 00:23:43,000 Speaker 1: be finding fossils of that civilization all over the place. Yeah, exactly. 422 00:23:43,440 --> 00:23:45,840 Speaker 1: That They that they hit on something we we've discussed 423 00:23:45,840 --> 00:23:47,400 Speaker 1: on the show before, which is, of course that the 424 00:23:47,440 --> 00:23:52,480 Speaker 1: fossil record is inherently incomplete, because fossilization only occurs when 425 00:23:52,520 --> 00:23:56,800 Speaker 1: conditions are just right. Um. They point out that that 426 00:23:56,880 --> 00:24:00,200 Speaker 1: of all the dinosaurs that ever lived, and there were 427 00:24:00,240 --> 00:24:03,280 Speaker 1: a ton of you know, uh, you know, they're the 428 00:24:03,680 --> 00:24:07,400 Speaker 1: era of the dinosaurs taken as as one gigantic, gigantic 429 00:24:07,440 --> 00:24:11,879 Speaker 1: monolith just dwarfs anything that that that that humanity has 430 00:24:11,920 --> 00:24:14,520 Speaker 1: ever occupied. Uh. You know, it is a it is 431 00:24:14,520 --> 00:24:17,920 Speaker 1: a cathedral, and and we're we're not even like a 432 00:24:18,000 --> 00:24:23,400 Speaker 1: child's dollhouse, uh sort of situation here. Um. So uh, 433 00:24:23,440 --> 00:24:25,760 Speaker 1: you know, out of out of all of those dinosaurs 434 00:24:25,760 --> 00:24:27,800 Speaker 1: that ever lived, there are only a few thousand near 435 00:24:27,840 --> 00:24:30,960 Speaker 1: complete specimens. And so the authors here contend that given 436 00:24:31,000 --> 00:24:34,199 Speaker 1: the rarity of fossilization, a species is short lived, as 437 00:24:34,240 --> 00:24:37,520 Speaker 1: Homo sapiens might not make it into the fossil record 438 00:24:37,640 --> 00:24:40,920 Speaker 1: at all. And of course, for fossilization to mean anything 439 00:24:41,160 --> 00:24:44,440 Speaker 1: to us, or to you know, anybody who's doing a 440 00:24:44,640 --> 00:24:46,720 Speaker 1: uh doing you know, some sort of an investigation of 441 00:24:46,760 --> 00:24:50,040 Speaker 1: a planet or our planet, those fossilizations would have to 442 00:24:50,080 --> 00:24:53,400 Speaker 1: survive and then they would have to be found. Yeah, exactly. 443 00:24:53,480 --> 00:24:56,520 Speaker 1: And and so again this might be pushing against your intuition. 444 00:24:56,560 --> 00:24:58,480 Speaker 1: You would say, like, wait a minute, there's there's there's 445 00:24:58,520 --> 00:25:01,480 Speaker 1: there's signs of human life all over the surface of Earth. 446 00:25:01,520 --> 00:25:03,640 Speaker 1: And and we have, you know, at least a few 447 00:25:03,680 --> 00:25:07,800 Speaker 1: thousand uh complete dinosaur fossils, enough to have museums of 448 00:25:07,880 --> 00:25:11,560 Speaker 1: natural history with dinosaur fossils in places all over the world. Uh, 449 00:25:11,720 --> 00:25:15,480 Speaker 1: surely you'd expect more. But dinosaurs existed for almost two 450 00:25:15,600 --> 00:25:20,800 Speaker 1: hundred million years. Human civilization again is like it's a 451 00:25:20,840 --> 00:25:25,000 Speaker 1: few thousand years at this point. Yeah. So the problem 452 00:25:25,040 --> 00:25:28,359 Speaker 1: here is like we have trouble comparing the odds because 453 00:25:28,880 --> 00:25:32,800 Speaker 1: you're not realizing how many millions of times more the 454 00:25:32,960 --> 00:25:38,320 Speaker 1: dinosaur bodies got to roll the dice than ours would. Yeah. Absolutely. 455 00:25:38,840 --> 00:25:41,320 Speaker 1: Another thing they touch on is that is the example 456 00:25:41,320 --> 00:25:44,600 Speaker 1: of technology. Uh, and they point out how rarely complex 457 00:25:44,680 --> 00:25:48,119 Speaker 1: early examples of human technology are ever found. So if 458 00:25:48,160 --> 00:25:50,920 Speaker 1: you're thinking, well, surely we would find one of these 459 00:25:50,960 --> 00:25:53,880 Speaker 1: factories or something that was made by one of these 460 00:25:53,920 --> 00:25:59,040 Speaker 1: factories that a previous civilization might have had, well not necessarily. Yeah, 461 00:25:59,080 --> 00:26:02,199 Speaker 1: sure surely my rice cooker would be found hundreds of 462 00:26:02,200 --> 00:26:04,919 Speaker 1: millions of years in the future. But yeah, that they 463 00:26:05,440 --> 00:26:09,040 Speaker 1: mentioned several reasons why that's maybe not as clear as 464 00:26:09,040 --> 00:26:13,160 Speaker 1: you might assume. So they say urbanization that currently represents 465 00:26:13,200 --> 00:26:16,520 Speaker 1: less than one percent of the Earth's surface, So that's 466 00:26:16,520 --> 00:26:19,679 Speaker 1: a limitation on the deposition side of of creating a 467 00:26:19,680 --> 00:26:23,119 Speaker 1: fossil record of our current civilization. Only small parts of 468 00:26:23,160 --> 00:26:27,280 Speaker 1: Earth's surface are actually inhabited by humans. That that sounds counterintuitive, 469 00:26:27,320 --> 00:26:31,080 Speaker 1: but it's true. And then they point out that quote 470 00:26:31,119 --> 00:26:35,400 Speaker 1: exposed sections and drilling sites for pre quaternary surfaces are 471 00:26:35,520 --> 00:26:39,520 Speaker 1: orders of magnitude less as fractions of the original surface. 472 00:26:39,840 --> 00:26:43,639 Speaker 1: So human civilization currently only feels a small portion of 473 00:26:43,680 --> 00:26:49,040 Speaker 1: Earth's surface right now, and we only access tiny fractions 474 00:26:49,080 --> 00:26:52,440 Speaker 1: of Earth's previous surface through through various kinds of drilling 475 00:26:52,520 --> 00:26:56,359 Speaker 1: and you know, access through exposure to rock strata. So 476 00:26:56,400 --> 00:27:00,919 Speaker 1: there's just like extreme selection filters on both sides, on 477 00:27:00,960 --> 00:27:04,280 Speaker 1: the deposition and on the excavation side. Yeah, it would 478 00:27:04,280 --> 00:27:07,600 Speaker 1: be kind of like even if you you knew somehow, 479 00:27:07,640 --> 00:27:10,800 Speaker 1: with some certainty that there was that that there was 480 00:27:10,800 --> 00:27:15,520 Speaker 1: a technological civilization during this time in the ancient ancient past. Uh, yeah, 481 00:27:15,600 --> 00:27:17,560 Speaker 1: you would. You would have to you have to really 482 00:27:17,600 --> 00:27:19,879 Speaker 1: know exactly where to drill down to hit them. You 483 00:27:19,920 --> 00:27:22,760 Speaker 1: couldn't just expect to randomly do it unless you did 484 00:27:23,160 --> 00:27:27,320 Speaker 1: a lot of drilling and digging and and excavation. Um. 485 00:27:28,040 --> 00:27:30,680 Speaker 1: But but but so what we've been talking about here 486 00:27:30,840 --> 00:27:34,560 Speaker 1: is challenging the the intuition that you would just be 487 00:27:34,680 --> 00:27:39,959 Speaker 1: finding physical fossil remnants and artifacts of this civilization from 488 00:27:40,040 --> 00:27:42,680 Speaker 1: hundreds of millions of years ago all over the place. 489 00:27:42,720 --> 00:27:44,520 Speaker 1: And I think they do a very good job of 490 00:27:44,600 --> 00:27:47,720 Speaker 1: knocking that down. But of course it is not hopeless 491 00:27:47,720 --> 00:27:49,800 Speaker 1: because they say, while our chance of finding the physical 492 00:27:49,840 --> 00:27:53,920 Speaker 1: remains of a hypothetical Silarian civilization might be very low, 493 00:27:54,359 --> 00:27:56,679 Speaker 1: there would be other traces of the existence of that 494 00:27:56,720 --> 00:28:00,520 Speaker 1: civilization that would be preserved in the geologic record, and 495 00:28:00,960 --> 00:28:03,080 Speaker 1: you you would have a very good chance of finding 496 00:28:03,119 --> 00:28:06,480 Speaker 1: those traces. Yeah, and that's that's what most of the 497 00:28:06,560 --> 00:28:08,040 Speaker 1: rest of the paper deals with. I do want to 498 00:28:08,040 --> 00:28:10,080 Speaker 1: point out one of the things that they bring up 499 00:28:10,080 --> 00:28:12,640 Speaker 1: in passing that I thought was interesting. They point out 500 00:28:12,680 --> 00:28:15,520 Speaker 1: that that you could certainly make an argument for or 501 00:28:15,560 --> 00:28:18,560 Speaker 1: against the evolution of intelligent life in a world based 502 00:28:18,600 --> 00:28:21,480 Speaker 1: on the probable evolution of species that are in the 503 00:28:21,520 --> 00:28:26,800 Speaker 1: fossil record, but that they would be focusing on physiochemical 504 00:28:27,280 --> 00:28:30,840 Speaker 1: tracers for previous industrial civilization. So I hadn't really thought 505 00:28:30,840 --> 00:28:33,800 Speaker 1: about this, but like the idea of like looking at say, 506 00:28:34,080 --> 00:28:38,720 Speaker 1: dinosaur fossils and saying, well, we don't have evidence that 507 00:28:38,800 --> 00:28:43,000 Speaker 1: they evolved in into an intelligent technological species, but if 508 00:28:43,040 --> 00:28:45,400 Speaker 1: we but we can make an argument based on this 509 00:28:45,480 --> 00:28:47,760 Speaker 1: fossil and this fosil fossil that they were headed in 510 00:28:47,800 --> 00:28:50,240 Speaker 1: that direction. I feel like even that's the kind of 511 00:28:50,240 --> 00:28:53,000 Speaker 1: thing that probably wouldn't be quite as clear as your 512 00:28:53,040 --> 00:28:55,680 Speaker 1: intuition might lead you to assign them, because I mean, 513 00:28:55,760 --> 00:29:01,960 Speaker 1: like intelligence in mammals arose very rapidly in geologic time. Yeah, 514 00:29:02,040 --> 00:29:05,320 Speaker 1: So again it reached this situation where the fossil record 515 00:29:05,720 --> 00:29:09,200 Speaker 1: could just be missing that snapshot entirely. So this all 516 00:29:09,280 --> 00:29:11,320 Speaker 1: leads you the next to the next major question. Given 517 00:29:11,360 --> 00:29:14,320 Speaker 1: the limits of what we can dettacked in the geochemical record, 518 00:29:14,640 --> 00:29:17,360 Speaker 1: what exactly could we look for on a planet to 519 00:29:17,400 --> 00:29:21,480 Speaker 1: see if an industrial society ever existed there? And yeah, 520 00:29:21,520 --> 00:29:23,600 Speaker 1: that's what the bulk of the paper focuses on. So 521 00:29:23,640 --> 00:29:27,280 Speaker 1: in the case of Earth, if an organized, intelligent society 522 00:29:27,320 --> 00:29:32,520 Speaker 1: evolved during the pre Quaternary time but they didn't reach 523 00:29:32,600 --> 00:29:35,360 Speaker 1: the level of an industrial society, there simply would be 524 00:29:35,400 --> 00:29:38,080 Speaker 1: no record of them as far as this paper is concerned. 525 00:29:38,640 --> 00:29:42,720 Speaker 1: Right there, they're looking for the kinds of chemical, material 526 00:29:42,880 --> 00:29:45,520 Speaker 1: and climate type changes that would leave a trace in 527 00:29:45,560 --> 00:29:48,520 Speaker 1: the geologic record, and that would primarily be a function 528 00:29:48,880 --> 00:29:54,480 Speaker 1: of of industry, basically of energy, production of of material 529 00:29:54,560 --> 00:29:58,640 Speaker 1: working things like metals and plastics, and the uh and 530 00:29:58,760 --> 00:30:02,600 Speaker 1: the methods of harn using energy for industrial use. I 531 00:30:02,680 --> 00:30:08,160 Speaker 1: was reminded of our episodes on fire technology because if 532 00:30:08,240 --> 00:30:11,160 Speaker 1: listeners may remember, we discussed, well, could something that evolved 533 00:30:11,200 --> 00:30:13,760 Speaker 1: in the water or or on a water world, could 534 00:30:13,800 --> 00:30:16,800 Speaker 1: they ever really get any kind of advanced technology going 535 00:30:17,160 --> 00:30:19,840 Speaker 1: if they didn't have access to the surface, and that 536 00:30:19,880 --> 00:30:21,600 Speaker 1: seems to be a factor here as well, as they're 537 00:30:21,600 --> 00:30:24,600 Speaker 1: only looking at the period during which something could have 538 00:30:24,720 --> 00:30:28,160 Speaker 1: evolved on land. Yeah, so you could maybe have advanced 539 00:30:28,200 --> 00:30:31,840 Speaker 1: intelligence in the water. But it's maybe this is just 540 00:30:31,880 --> 00:30:33,680 Speaker 1: a lack of imagination on our part. You know, you 541 00:30:33,720 --> 00:30:36,480 Speaker 1: always need to be aware of the limitations of your vision. 542 00:30:36,600 --> 00:30:40,200 Speaker 1: But it does seem hard to imagine advanced technology under 543 00:30:40,200 --> 00:30:43,000 Speaker 1: the water, because like if you don't have fire, you 544 00:30:43,040 --> 00:30:45,880 Speaker 1: can't do metal working, or metal working is very difficult. 545 00:30:45,960 --> 00:30:47,600 Speaker 1: I don't I don't know. It just seems harder to 546 00:30:47,640 --> 00:30:50,880 Speaker 1: imagine how technology like we understand it could come about 547 00:30:50,960 --> 00:30:54,240 Speaker 1: in the water. But again, you know, limits of our vision. Yeah, 548 00:30:54,320 --> 00:30:56,240 Speaker 1: so they say, quote, the focus is thus on the 549 00:30:56,240 --> 00:30:59,120 Speaker 1: period between the emergence of complex life on land in 550 00:30:59,360 --> 00:31:02,960 Speaker 1: the Devonian four million years ago in the Paleozoic era 551 00:31:03,360 --> 00:31:06,480 Speaker 1: and the mid appli A scene. Uh, and that's around 552 00:31:06,560 --> 00:31:09,560 Speaker 1: four million years ago, Yeah, because if it was much 553 00:31:09,600 --> 00:31:12,560 Speaker 1: more recent, you'd you'd probably get into the area where 554 00:31:12,560 --> 00:31:15,040 Speaker 1: you'd start to expect to actually see those kinds of 555 00:31:15,520 --> 00:31:18,600 Speaker 1: remnants and artifacts that that we were talking about. Right, 556 00:31:19,280 --> 00:31:21,760 Speaker 1: So they get into the discussion of what we might 557 00:31:21,880 --> 00:31:25,120 Speaker 1: look for, and they haven't nicely divided up. The first 558 00:31:25,120 --> 00:31:29,000 Speaker 1: one is, uh, well, they basically have two broad categories 559 00:31:29,000 --> 00:31:32,880 Speaker 1: and then some some details on that category. The first 560 00:31:32,920 --> 00:31:36,360 Speaker 1: big one though, would be looking at the geological footprint 561 00:31:36,520 --> 00:31:39,280 Speaker 1: of the anthroposcene. So, as we've discussed in the show before, 562 00:31:39,320 --> 00:31:41,320 Speaker 1: there's an argument to be made that the impact of 563 00:31:41,400 --> 00:31:44,719 Speaker 1: human civilization on the environment and the geologic record constitutes 564 00:31:44,760 --> 00:31:49,280 Speaker 1: its own geologic era, the Anthropocene. So not all the 565 00:31:49,360 --> 00:31:52,080 Speaker 1: changes would be recognizable millions of years later, but some 566 00:31:52,160 --> 00:31:56,720 Speaker 1: would be. Right. So, human activity at this point is 567 00:31:56,720 --> 00:32:00,240 Speaker 1: is large scale enough that we are making change is 568 00:32:00,280 --> 00:32:04,480 Speaker 1: to the earth that that are that are widespread or 569 00:32:04,600 --> 00:32:07,760 Speaker 1: you could even say global, And I was gonna say permanent, 570 00:32:07,800 --> 00:32:10,480 Speaker 1: not permanent, but extremely long lived. You know, going way 571 00:32:10,560 --> 00:32:13,840 Speaker 1: into the future, you will be able to find signs 572 00:32:13,880 --> 00:32:16,440 Speaker 1: in the rocks and the ice and the setiment, you know, 573 00:32:16,560 --> 00:32:19,000 Speaker 1: the things on Earth that persists over long periods of 574 00:32:19,000 --> 00:32:22,000 Speaker 1: time that will leave records of what we did to 575 00:32:22,080 --> 00:32:25,480 Speaker 1: the earth in just the past three years or so. Right, 576 00:32:26,040 --> 00:32:29,560 Speaker 1: And uh, And as we've probably mentioned before, the anthropasyn 577 00:32:29,680 --> 00:32:33,959 Speaker 1: is not a an official geological era as much as 578 00:32:34,000 --> 00:32:36,160 Speaker 1: any of these things can be, you know, official if 579 00:32:36,360 --> 00:32:38,440 Speaker 1: it seems like when you're talking about geologic terms, it's 580 00:32:38,480 --> 00:32:42,040 Speaker 1: even more ridiculous. We can consider such a small part 581 00:32:42,080 --> 00:32:45,560 Speaker 1: of geologic history that we occupy, but there's a lot 582 00:32:45,600 --> 00:32:48,240 Speaker 1: of compelling evidence for it, and you often see it discussed, 583 00:32:48,320 --> 00:32:52,040 Speaker 1: especially when we're talking about the changes that that humans 584 00:32:52,040 --> 00:32:54,400 Speaker 1: have made to the planet and are still making to 585 00:32:54,440 --> 00:32:56,920 Speaker 1: the planet and how they may show up in the 586 00:32:56,960 --> 00:32:59,959 Speaker 1: geologic record. And just to be super clear, the majority 587 00:33:00,000 --> 00:33:01,880 Speaker 1: any of the changes we're talking about of this kind 588 00:33:02,200 --> 00:33:06,160 Speaker 1: would not be changes like physical alterations of the Earth's surface. 589 00:33:06,400 --> 00:33:09,480 Speaker 1: We're not talking about like records of people digging holes 590 00:33:09,560 --> 00:33:13,360 Speaker 1: and building stuff. We're talking about records of like changes 591 00:33:13,480 --> 00:33:18,080 Speaker 1: to the to the level of different carbon isotopes in 592 00:33:18,080 --> 00:33:21,840 Speaker 1: in geological strata and things like that. Right now, they 593 00:33:21,880 --> 00:33:23,960 Speaker 1: also hit upon something that that I thought was really 594 00:33:24,000 --> 00:33:27,480 Speaker 1: interesting and in a way almost almost encouraging, uh, the 595 00:33:27,520 --> 00:33:31,040 Speaker 1: sustainability paradox. So the idea here is that of course 596 00:33:31,040 --> 00:33:36,440 Speaker 1: the longer human civilization lasts, especially technological civilization, the greater 597 00:33:36,520 --> 00:33:40,920 Speaker 1: the geologic signal of its impact. Again, that that lasting 598 00:33:41,000 --> 00:33:44,080 Speaker 1: those lasting signs in the environment, not the faces they 599 00:33:44,080 --> 00:33:49,280 Speaker 1: carved into the mountains but impacts again on their their 600 00:33:49,320 --> 00:33:54,240 Speaker 1: geochemical and nature. Um, so that signal increases. But the 601 00:33:54,360 --> 00:33:59,160 Speaker 1: longer human civilization lasts, the more sustainable it must become 602 00:33:59,200 --> 00:34:01,880 Speaker 1: in order to revive. And this is of course the 603 00:34:01,920 --> 00:34:05,520 Speaker 1: reality we're living in right now. If a civilization survives 604 00:34:05,560 --> 00:34:10,480 Speaker 1: this test and becomes more sustainable, then that signal grows weaker. Right. 605 00:34:10,520 --> 00:34:12,960 Speaker 1: So it's almost like the strength of the signal left 606 00:34:13,000 --> 00:34:17,000 Speaker 1: for future people to discover is directly proportional to how 607 00:34:17,040 --> 00:34:21,920 Speaker 1: suicidal that civilization is, right Like, the more it is 608 00:34:21,960 --> 00:34:25,439 Speaker 1: just burning through fossil fuel resources and the rate of that, 609 00:34:25,840 --> 00:34:28,480 Speaker 1: the stronger the signal will be. And so a civilization 610 00:34:28,520 --> 00:34:32,160 Speaker 1: at some point, they say, well, will naturally tend to 611 00:34:32,200 --> 00:34:36,120 Speaker 1: attenuate for a couple of reasons. Either it realizes it 612 00:34:36,160 --> 00:34:38,239 Speaker 1: can't keep going at that rate, or it's going to 613 00:34:38,440 --> 00:34:42,000 Speaker 1: cause climate damage to itself, so it will naturally switch 614 00:34:42,040 --> 00:34:45,560 Speaker 1: to more sustainable uh energy sources that are harder to 615 00:34:45,640 --> 00:34:48,239 Speaker 1: detect in the future, or it of course does so 616 00:34:48,320 --> 00:34:51,440 Speaker 1: much damage to itself that it's signal naturally is reduced, 617 00:34:52,040 --> 00:34:54,640 Speaker 1: right right. So, so basically coming back to what you 618 00:34:54,640 --> 00:34:56,600 Speaker 1: said earlier, it's not just that there there's gonna be 619 00:34:56,640 --> 00:34:59,320 Speaker 1: a sign. There's gonna be the signal, uh, this footprint 620 00:34:59,360 --> 00:35:02,120 Speaker 1: of a civilized ation, uh in the in the you know, 621 00:35:02,160 --> 00:35:04,840 Speaker 1: the geochemical record. It's it's also that it may just 622 00:35:04,920 --> 00:35:07,279 Speaker 1: be very short. It may be a little it's not 623 00:35:07,320 --> 00:35:09,880 Speaker 1: going to be this. Uh, it's not gonna be a symphony. 624 00:35:09,960 --> 00:35:12,720 Speaker 1: It's going to maybe be a note or two. So basically, 625 00:35:12,719 --> 00:35:16,319 Speaker 1: the idea being that that that a real strong, much 626 00:35:16,360 --> 00:35:21,000 Speaker 1: stronger argument for aliens existing and having some sort of 627 00:35:21,080 --> 00:35:23,160 Speaker 1: role or some sort of advanced technology having some sort 628 00:35:23,200 --> 00:35:26,400 Speaker 1: of role on Earth in the in the ancient history 629 00:35:26,880 --> 00:35:29,880 Speaker 1: would not be look at the pyramids, I think aliens 630 00:35:29,920 --> 00:35:32,920 Speaker 1: did this, or I think, you know, ancient scientists did this. 631 00:35:33,360 --> 00:35:36,200 Speaker 1: It would be pointing at say a blip in uh, 632 00:35:36,280 --> 00:35:38,960 Speaker 1: you know, or an increase in global temperatures during a 633 00:35:38,960 --> 00:35:41,760 Speaker 1: certain period of time and saying, I think the aliens 634 00:35:41,760 --> 00:35:45,000 Speaker 1: did this, or I think the advanced technology in question 635 00:35:45,040 --> 00:35:47,520 Speaker 1: did this. I mean, even then, I think that would 636 00:35:47,560 --> 00:35:51,040 Speaker 1: be a very speculative and and difficult to prove hypothesis. 637 00:35:51,080 --> 00:35:54,400 Speaker 1: It would be kind of just like unfalsifiable speculation, but 638 00:35:55,120 --> 00:35:59,120 Speaker 1: that that would perhaps be the more likely type of 639 00:35:59,200 --> 00:36:02,640 Speaker 1: signal you would find if there had been alien intervention, 640 00:36:02,760 --> 00:36:12,640 Speaker 1: then you know specific artifacts than all right, well, let's 641 00:36:12,640 --> 00:36:14,560 Speaker 1: get into some of the specifics of the footprint that 642 00:36:14,640 --> 00:36:17,360 Speaker 1: the authors lay out here. The first one is a 643 00:36:17,480 --> 00:36:22,319 Speaker 1: stable isotope anomalies of carbon, oxygen, hydrogen, and nitrogen. And 644 00:36:22,480 --> 00:36:24,720 Speaker 1: this is one of the big ones, an estimated point 645 00:36:24,760 --> 00:36:28,160 Speaker 1: five trillion tons of fossil carbon via the burning of 646 00:36:28,160 --> 00:36:32,360 Speaker 1: fossil fuels and warming of the planet. Um they quote, 647 00:36:32,400 --> 00:36:35,480 Speaker 1: we we expect this temperature rise to be detectable and 648 00:36:35,600 --> 00:36:40,520 Speaker 1: surface ocean uh carbonates, notably for Manifera. This is a 649 00:36:40,600 --> 00:36:44,799 Speaker 1: single celled organism with with with a chalky shell. UM. 650 00:36:44,960 --> 00:36:52,000 Speaker 1: Organic biomarkers cave records, such such as stalactites, lake ostracods. 651 00:36:52,080 --> 00:36:56,760 Speaker 1: These are minute aquatic crustaceans and high latitude ice cores, 652 00:36:57,040 --> 00:36:59,279 Speaker 1: though only the first two of these will be a 653 00:36:59,360 --> 00:37:03,759 Speaker 1: retrievable in the time scales considered here. Right, So this 654 00:37:03,840 --> 00:37:07,360 Speaker 1: thing about the the isotope anomalies of of carbon and 655 00:37:07,440 --> 00:37:09,840 Speaker 1: these other elements is very interesting. So they say, you know, 656 00:37:09,880 --> 00:37:12,920 Speaker 1: there are natural distributions that you would find records of 657 00:37:13,200 --> 00:37:16,359 Speaker 1: in the different isotopes of carbon that are that are 658 00:37:16,480 --> 00:37:20,640 Speaker 1: moving around in Earth's atmosphere. But when people suddenly start 659 00:37:20,680 --> 00:37:25,560 Speaker 1: pulling huge amounts of fossil carbon, carbon of a biological 660 00:37:25,600 --> 00:37:28,640 Speaker 1: origin out of the ground and burning it, you suddenly 661 00:37:28,680 --> 00:37:31,960 Speaker 1: start throwing those isotopes out of whack, and that will 662 00:37:32,000 --> 00:37:35,040 Speaker 1: be something that will leave records for millions of years 663 00:37:35,080 --> 00:37:38,000 Speaker 1: to come. So you you can look in the geological records, 664 00:37:38,040 --> 00:37:40,680 Speaker 1: you know, the record of of strata from previous eras, 665 00:37:40,680 --> 00:37:43,920 Speaker 1: and say, huh, for some reason, in this one period 666 00:37:44,000 --> 00:37:47,359 Speaker 1: deep in history, suddenly the carbon isotopes got way out 667 00:37:47,400 --> 00:37:51,160 Speaker 1: of whack, as if suddenly a bunch of fossil carbon 668 00:37:51,239 --> 00:37:54,000 Speaker 1: like coal or oil or whatever had been burned at 669 00:37:54,000 --> 00:37:57,040 Speaker 1: a at a hideous rate into the atmosphere. Right. And 670 00:37:57,080 --> 00:38:00,080 Speaker 1: so you know, looking at our our time now of 671 00:38:00,080 --> 00:38:02,759 Speaker 1: of of modern human civilization, you know this that we 672 00:38:02,800 --> 00:38:05,719 Speaker 1: have this fossil fuel consumption, and we have the invention 673 00:38:05,800 --> 00:38:09,080 Speaker 1: of the haber Bosch process and the large scale use 674 00:38:09,120 --> 00:38:13,880 Speaker 1: of of nitrogenous fertilizers and agriculture, which will also heavily 675 00:38:13,920 --> 00:38:18,120 Speaker 1: impact the planet's nitrogen cycling. Yeah, the haber Bosch process. Yeah, 676 00:38:18,120 --> 00:38:20,960 Speaker 1: as part of the changes in the nitrogen cycle that 677 00:38:21,000 --> 00:38:24,600 Speaker 1: have come about as a result of of industrial civilization 678 00:38:24,640 --> 00:38:28,600 Speaker 1: as well, they also touched on sediment to logical records. 679 00:38:29,080 --> 00:38:32,400 Speaker 1: The key causes here would be major soil erosion brought 680 00:38:32,440 --> 00:38:38,160 Speaker 1: on by agriculture, but also by agriculture related deforestation. Um. Now, 681 00:38:38,160 --> 00:38:41,359 Speaker 1: this would be partially mitigated by dams, they point out, 682 00:38:41,560 --> 00:38:45,160 Speaker 1: but erosion is also heightened by climate changes and thawing 683 00:38:45,280 --> 00:38:50,320 Speaker 1: perma frost. Also sediment content changes due to just industrialization 684 00:38:50,360 --> 00:38:53,440 Speaker 1: in general. Uh. Now, here's a Here's another big one 685 00:38:53,480 --> 00:38:58,560 Speaker 1: that I think will be pretty obvious. Faunnel radiation and extinctions. Um. Basically, 686 00:38:58,640 --> 00:39:01,040 Speaker 1: humans have brought about many extinct actions already, and we're 687 00:39:01,080 --> 00:39:04,480 Speaker 1: living in the midst of an extinction event. Uh. This 688 00:39:04,520 --> 00:39:08,520 Speaker 1: will likely register in the fossil record. Yeah. Now, of course, 689 00:39:08,840 --> 00:39:13,120 Speaker 1: previous major extinction events have usually been chalked up to 690 00:39:13,480 --> 00:39:17,520 Speaker 1: two natural things like uh oh, we can track massive 691 00:39:17,600 --> 00:39:20,600 Speaker 1: vulcanism as as the cause of this one, or say 692 00:39:20,640 --> 00:39:25,160 Speaker 1: a large space impact like the Kti extinction event. But 693 00:39:25,239 --> 00:39:28,000 Speaker 1: there are other extinction events in Earth's history where the 694 00:39:28,080 --> 00:39:31,680 Speaker 1: cause is not totally clear. You know, there are some speculations, 695 00:39:31,680 --> 00:39:34,120 Speaker 1: but we don't know exactly why. Suddenly, it seemed like 696 00:39:34,160 --> 00:39:37,480 Speaker 1: there was a great reduction in marine biodiversity at this 697 00:39:37,560 --> 00:39:40,200 Speaker 1: point in history. All right. The next area is non 698 00:39:40,320 --> 00:39:44,520 Speaker 1: naturally occurring synthetics, so non naturally occurring chemicals generated by 699 00:39:44,560 --> 00:39:49,719 Speaker 1: industrial activity that persists in the environment. Things persistent organic pollutants, 700 00:39:50,040 --> 00:39:54,160 Speaker 1: chlorofluoral carbons, in related compounds. And they also point out 701 00:39:54,160 --> 00:39:58,840 Speaker 1: that steroids, leaf waxes, alkanones, and lipids can be preserved 702 00:39:58,840 --> 00:40:01,719 Speaker 1: in sediment for many millions of years. Now, that one 703 00:40:01,800 --> 00:40:05,200 Speaker 1: naturally makes me think of King plastic baby. Yeah, yeah, 704 00:40:05,200 --> 00:40:07,920 Speaker 1: And that's that's the next thing that they mentioned. And 705 00:40:07,960 --> 00:40:11,480 Speaker 1: this one's you know, this one's disheartening but obvious. We've 706 00:40:11,520 --> 00:40:15,640 Speaker 1: created tons of plastics, tons upon tons upon tons of plastics, 707 00:40:15,719 --> 00:40:19,120 Speaker 1: and they sadly persist not only in heaps and floating masses, 708 00:40:19,160 --> 00:40:23,959 Speaker 1: but inside the bodies of organisms, including ourselves, uh so quote. 709 00:40:24,000 --> 00:40:29,040 Speaker 1: The potential for very long term persistence and detectability is high. Now, 710 00:40:29,080 --> 00:40:31,040 Speaker 1: one of the things they point out about plastic that's 711 00:40:31,080 --> 00:40:34,759 Speaker 1: interesting is that plastics may well prove to be a 712 00:40:34,880 --> 00:40:38,520 Speaker 1: very long term signature of human civilization and the geologic 713 00:40:38,600 --> 00:40:41,279 Speaker 1: record for you know, millions and millions of years to come. 714 00:40:41,400 --> 00:40:43,839 Speaker 1: But the development of plastic is also something they would 715 00:40:43,880 --> 00:40:46,080 Speaker 1: class under the I don't remember the umbrella term they 716 00:40:46,160 --> 00:40:50,560 Speaker 1: use for this sort of chemical contingencies. A technological civilization 717 00:40:50,640 --> 00:40:54,320 Speaker 1: does not have to use plastics. Plastics are just something 718 00:40:54,400 --> 00:40:57,799 Speaker 1: that humans happen to use. There are other things that 719 00:40:57,880 --> 00:41:03,279 Speaker 1: seem probably more universal, like almost any industrial civilization you 720 00:41:03,280 --> 00:41:07,719 Speaker 1: would expect to burn lots of fossil fuels. But plastics, 721 00:41:07,719 --> 00:41:10,359 Speaker 1: that's more of a question mark. Is that unusual that 722 00:41:10,400 --> 00:41:12,399 Speaker 1: we did it, or is that a very common thing 723 00:41:12,520 --> 00:41:15,800 Speaker 1: that the civilizations would do all right. The next area 724 00:41:15,840 --> 00:41:21,480 Speaker 1: that they highlight transuranic elements. These are elements having a 725 00:41:21,560 --> 00:41:26,160 Speaker 1: higher atomic number than uranium, which is ninety two. Most 726 00:41:26,239 --> 00:41:30,560 Speaker 1: radioactive isotopes created via nuclear energy or weaponry have long 727 00:41:31,000 --> 00:41:33,680 Speaker 1: half lives, but not long enough to be a factor 728 00:41:33,760 --> 00:41:35,960 Speaker 1: on the time scale that they're talking about here. But 729 00:41:36,040 --> 00:41:40,640 Speaker 1: the exceptions are plutonium to forty four and M curium 730 00:41:40,719 --> 00:41:43,880 Speaker 1: two forty seven, So plutonium has a half life of 731 00:41:44,120 --> 00:41:48,120 Speaker 1: eight point eight million years, and curium in this case, 732 00:41:48,200 --> 00:41:50,839 Speaker 1: we're talking about a half life of fifteen million years. 733 00:41:50,880 --> 00:41:54,360 Speaker 1: So in sufficient quantities of disposal, these would these would 734 00:41:54,480 --> 00:41:59,120 Speaker 1: pop up. And plutonium has no known natural causes outside 735 00:41:59,120 --> 00:42:02,400 Speaker 1: of an actual bernova or something like that. This isotope 736 00:42:02,440 --> 00:42:05,560 Speaker 1: of plutonium. Yes, this particular yea plutonium two forty four 737 00:42:05,640 --> 00:42:08,759 Speaker 1: so um. So yeah, if you found enough of this 738 00:42:09,200 --> 00:42:11,840 Speaker 1: uh in the geologic record, that would be a sign 739 00:42:11,920 --> 00:42:14,239 Speaker 1: that's that something was at work, there was some sort 740 00:42:14,280 --> 00:42:20,440 Speaker 1: of technological atomic uh enterprise that was in place. Now, 741 00:42:20,440 --> 00:42:24,160 Speaker 1: I guess we've already mentioned earlier that the authors are 742 00:42:24,200 --> 00:42:27,640 Speaker 1: not going to claim that there was in fact a 743 00:42:27,640 --> 00:42:30,919 Speaker 1: a long lost civilization hundreds of millions of years ago. 744 00:42:31,360 --> 00:42:34,719 Speaker 1: But they do actually look at the geologic record to say, 745 00:42:35,360 --> 00:42:39,319 Speaker 1: are there anythings that that match these criteria we've been 746 00:42:39,320 --> 00:42:42,640 Speaker 1: looking at, And they do find some interesting partial matches 747 00:42:42,719 --> 00:42:45,640 Speaker 1: that though of course nothing really comes close to evidence 748 00:42:45,680 --> 00:42:48,319 Speaker 1: that would be conclusive that there actually was a civilization, 749 00:42:48,360 --> 00:42:52,160 Speaker 1: but some of these matches raise interesting questions of their own. Yeah, 750 00:42:52,400 --> 00:42:54,440 Speaker 1: they don't look at everything, and they point out that 751 00:42:54,480 --> 00:42:56,960 Speaker 1: things like the KT extinction event, we know that that 752 00:42:57,040 --> 00:43:01,440 Speaker 1: was not an industrial accident or anything, um and uh. 753 00:43:01,480 --> 00:43:03,880 Speaker 1: And and again they're not arguing that these are evidence 754 00:43:03,880 --> 00:43:06,680 Speaker 1: of past pre human industrial civilizations on Earth, but merely 755 00:43:06,719 --> 00:43:09,000 Speaker 1: point to them as the sources of events we might 756 00:43:09,080 --> 00:43:12,080 Speaker 1: look at. Yeah, and I would say the biggest one 757 00:43:12,239 --> 00:43:14,840 Speaker 1: that they focus on in the paper is the event 758 00:43:14,920 --> 00:43:18,640 Speaker 1: known as the Paleocene Eocene Thermal Maximum or p E 759 00:43:18,680 --> 00:43:21,880 Speaker 1: t M. Yeah. This is an abrupt spike in carbon 760 00:43:21,960 --> 00:43:27,840 Speaker 1: and oxygen isotopes near the Paleocene Eocene transition uh fifty 761 00:43:27,920 --> 00:43:30,760 Speaker 1: six million years ago, resulting in a five to eight 762 00:43:31,400 --> 00:43:35,439 Speaker 1: degree celsius global average temperature rise. This is widely thought 763 00:43:35,520 --> 00:43:37,640 Speaker 1: to be due to well, I think they're there are 764 00:43:37,640 --> 00:43:41,480 Speaker 1: different theories of One is that it's volcanic activity, um. 765 00:43:41,640 --> 00:43:44,759 Speaker 1: But there have also been hypotheses put forth that it 766 00:43:44,760 --> 00:43:47,200 Speaker 1: could have been a common impact. It could be due 767 00:43:47,200 --> 00:43:52,400 Speaker 1: to burning pete methane being released, and a few other candidates. Um. 768 00:43:52,400 --> 00:43:55,160 Speaker 1: It's also used as a means of of understanding and 769 00:43:55,239 --> 00:43:57,319 Speaker 1: kind of like kind of modeling out the effects of 770 00:43:57,360 --> 00:44:01,080 Speaker 1: climate change during our own era. Yeah. And and one 771 00:44:01,120 --> 00:44:03,520 Speaker 1: of the reasons this one gets singled out is, uh 772 00:44:03,960 --> 00:44:06,520 Speaker 1: so it really looks like, Okay, here we're seeing, for example, 773 00:44:06,560 --> 00:44:10,879 Speaker 1: these carbon isotope signature changes that would signal that huge 774 00:44:10,920 --> 00:44:15,440 Speaker 1: amounts of biogenic carbon carbon that originally came from life forms, 775 00:44:15,480 --> 00:44:17,840 Speaker 1: like the stuff you would find in fossil fuels, is 776 00:44:17,880 --> 00:44:20,879 Speaker 1: being burned and released into the atmosphere. Now, how would 777 00:44:20,960 --> 00:44:24,160 Speaker 1: that happen if if if it wasn't creatures from the 778 00:44:24,160 --> 00:44:27,759 Speaker 1: Black Lagoon with leather face masks digging up a bunch 779 00:44:27,840 --> 00:44:31,040 Speaker 1: of fossil fuels and burning them for their civilization. Well, no, 780 00:44:31,239 --> 00:44:33,880 Speaker 1: you probably don't need to jump to that conclusion, because 781 00:44:33,880 --> 00:44:37,120 Speaker 1: there are other solutions on offer, like, for example, there 782 00:44:37,200 --> 00:44:41,080 Speaker 1: might have somehow been lots of access of volcanic magma 783 00:44:41,320 --> 00:44:45,600 Speaker 1: two beds of fossil fuels. Maybe certain types of volcanic 784 00:44:45,640 --> 00:44:48,960 Speaker 1: activity tended to set a light to a lot of 785 00:44:49,440 --> 00:44:52,719 Speaker 1: natural reserves of fossil fuels and shale beds and things 786 00:44:52,800 --> 00:44:56,200 Speaker 1: like that. And this almost acted as if the Earth itself, 787 00:44:56,280 --> 00:44:58,920 Speaker 1: we're we're setting off an industrial revolution, but it was 788 00:44:59,000 --> 00:45:03,200 Speaker 1: just volcano interacting with with these reservoirs of carbon in 789 00:45:03,239 --> 00:45:06,360 Speaker 1: the ground. Yeah, all you need is geologic upheaval and 790 00:45:06,440 --> 00:45:10,000 Speaker 1: volcanic activity. And again um our our planet has a 791 00:45:10,160 --> 00:45:14,160 Speaker 1: as a as a very active geological life, so there's 792 00:45:14,160 --> 00:45:16,759 Speaker 1: plenty of opportunity for this sort of thing to potentially 793 00:45:16,760 --> 00:45:19,000 Speaker 1: have taken place. So it kind of comes back to 794 00:45:19,000 --> 00:45:21,359 Speaker 1: a problem with the signal here, the signal you would 795 00:45:21,360 --> 00:45:24,120 Speaker 1: be looking for in the geochemical record, in many cases, 796 00:45:24,719 --> 00:45:27,520 Speaker 1: the very sort of signal we're looking for especially concerning 797 00:45:27,560 --> 00:45:30,080 Speaker 1: carbon and warming, could have also been caused by these 798 00:45:30,160 --> 00:45:33,640 Speaker 1: naturally occurring causes, and so strong signals might be coming 799 00:45:33,680 --> 00:45:36,719 Speaker 1: from something else, and more specific signals that we might 800 00:45:36,760 --> 00:45:39,759 Speaker 1: look to just might be too weak to to ever 801 00:45:39,880 --> 00:45:42,600 Speaker 1: possibly observe or to really make much out of. Oh yeah, 802 00:45:42,800 --> 00:45:44,960 Speaker 1: this is an interesting paradox they talk about in their 803 00:45:44,960 --> 00:45:47,200 Speaker 1: conclusion of all of the criteria they're able to come 804 00:45:47,280 --> 00:45:50,000 Speaker 1: up with in this framework for for looking for past 805 00:45:50,080 --> 00:45:55,239 Speaker 1: industrial civilizations, the stuff that you would expect any industrial 806 00:45:55,320 --> 00:46:00,680 Speaker 1: civilization to do also has other explanations, and so so 807 00:46:00,719 --> 00:46:04,040 Speaker 1: it's not conclusive that it was an industrial civilization that 808 00:46:04,160 --> 00:46:07,200 Speaker 1: this would be things like, you know, the carbon stuff. Meanwhile, 809 00:46:07,360 --> 00:46:10,720 Speaker 1: the stuff that would be really strong evidence of of 810 00:46:11,080 --> 00:46:16,279 Speaker 1: an intelligent civilization origin, that stuff that civilizations might not do. 811 00:46:16,480 --> 00:46:19,200 Speaker 1: It's more contingent things like plastics and stuff. You know, 812 00:46:19,480 --> 00:46:22,200 Speaker 1: you could have a civilization without plastics. That's not a 813 00:46:22,320 --> 00:46:26,680 Speaker 1: necessary milestone in the in the progress of energy harnessing, 814 00:46:27,080 --> 00:46:29,160 Speaker 1: and maybe it's even the sort of thing, uh, an 815 00:46:29,200 --> 00:46:31,799 Speaker 1: advance civilization would move away from. Coming back to that 816 00:46:32,080 --> 00:46:36,200 Speaker 1: the sustainability paradox, when one could hope, I imagine now 817 00:46:36,400 --> 00:46:39,839 Speaker 1: the authors again they're very clear about just how far 818 00:46:39,880 --> 00:46:43,920 Speaker 1: you should take this hypothesis, stating that quote the Silarian 819 00:46:44,000 --> 00:46:48,319 Speaker 1: hypothesis cannot be regarded as likely merely because no other 820 00:46:48,440 --> 00:46:53,000 Speaker 1: valid idea presents itself. Uh So they admit that this 821 00:46:53,000 --> 00:46:54,560 Speaker 1: this sort of thing could easily get out of hand 822 00:46:54,560 --> 00:46:57,000 Speaker 1: with folks pointing to any sort of signal in the 823 00:46:57,040 --> 00:47:01,560 Speaker 1: geochemical record as being possible proof of human technological societies. 824 00:47:02,040 --> 00:47:04,600 Speaker 1: If you're doing that, you're you're really taking it and 825 00:47:04,640 --> 00:47:07,560 Speaker 1: running with in the wrong direction. Yeah, I guess that's 826 00:47:07,600 --> 00:47:10,920 Speaker 1: one of the frustrating things about about interesting work of 827 00:47:10,920 --> 00:47:12,880 Speaker 1: this kind is so you can point out a lot 828 00:47:12,920 --> 00:47:18,120 Speaker 1: of the ways that it's difficult to rule out past civilizations. 829 00:47:18,239 --> 00:47:20,560 Speaker 1: But then for a lot of people who just want 830 00:47:20,680 --> 00:47:24,160 Speaker 1: to have a theory that changes everything, you know, for 831 00:47:24,200 --> 00:47:26,600 Speaker 1: a lot it's just like it's fun to believe that. 832 00:47:26,960 --> 00:47:28,840 Speaker 1: So a lot of people just want to believe it. 833 00:47:28,880 --> 00:47:30,880 Speaker 1: I want to believe, you know, that there was an 834 00:47:30,920 --> 00:47:34,320 Speaker 1: Atlantis mother civilization that birthed everything, or I want to 835 00:47:34,360 --> 00:47:37,480 Speaker 1: believe that there were aliens on Earth before humans or 836 00:47:37,520 --> 00:47:40,359 Speaker 1: anything like that, because that would change everything, and it 837 00:47:40,400 --> 00:47:44,920 Speaker 1: feels so cool to believe it. Therefore, becomes your default belief, 838 00:47:45,080 --> 00:47:47,920 Speaker 1: and so thus a paper that says, well, it's more 839 00:47:47,960 --> 00:47:50,560 Speaker 1: difficult to rule out that kind of thing than you 840 00:47:50,640 --> 00:47:55,160 Speaker 1: might think. Uh, some people can erroneously conclude that that 841 00:47:55,280 --> 00:47:57,560 Speaker 1: is in fact evidence for the thing they want to 842 00:47:57,600 --> 00:48:03,359 Speaker 1: believe because it feels cool. It's not positive evidence for it, yes, yeah, absolutely, 843 00:48:03,840 --> 00:48:06,360 Speaker 1: um yes, So so you know, they argue that that 844 00:48:06,440 --> 00:48:09,720 Speaker 1: we need to to further research you know, the likely 845 00:48:09,800 --> 00:48:14,439 Speaker 1: signature uh left by our own um Anthropocene era, as 846 00:48:14,440 --> 00:48:18,319 Speaker 1: well as a deeper exploration of the elemental and um 847 00:48:18,480 --> 00:48:23,680 Speaker 1: compositional anomalies that we find in extant sediments. Basically, we 848 00:48:23,760 --> 00:48:27,040 Speaker 1: look at past events mainly with stuff like impacts in mind, 849 00:48:27,719 --> 00:48:31,200 Speaker 1: but perhaps the Silarian hypothesis needs to be at least 850 00:48:31,200 --> 00:48:34,239 Speaker 1: on the table as well. Not because again we think 851 00:48:34,320 --> 00:48:37,799 Speaker 1: it is, you know, actually a valid explanation for what 852 00:48:37,880 --> 00:48:41,480 Speaker 1: has happened. Um, you know, ultimately it's an outside possibility, 853 00:48:41,920 --> 00:48:44,600 Speaker 1: not a conclusion we should jump to, but perhaps it 854 00:48:44,600 --> 00:48:46,719 Speaker 1: should just be part of sort of the spectrum of 855 00:48:46,760 --> 00:48:51,680 Speaker 1: possibilities there again, not because we think it happened, but because, uh, 856 00:48:51,800 --> 00:48:53,160 Speaker 1: it gives us a little more of a sort of 857 00:48:53,160 --> 00:48:57,359 Speaker 1: a robust spectrum. And how to interpret these things and 858 00:48:57,360 --> 00:48:59,799 Speaker 1: and then moving forward to you know, potentially considering other worlds, 859 00:48:59,840 --> 00:49:02,960 Speaker 1: looking at other planets like even Mars. Uh. It gives 860 00:49:03,040 --> 00:49:06,520 Speaker 1: us one more tool, one more UH way to look 861 00:49:06,560 --> 00:49:10,080 Speaker 1: at the evidence. Yeah, exactly. They're not arguing this because 862 00:49:10,120 --> 00:49:13,520 Speaker 1: they think there was a civilization. It's that we should 863 00:49:13,600 --> 00:49:17,399 Speaker 1: consider these possibilities when looking at planets, even including our own, 864 00:49:17,680 --> 00:49:19,960 Speaker 1: and know what we would look for if we wanted 865 00:49:20,000 --> 00:49:23,040 Speaker 1: to consider that possibility, right, Because ultimately this is not 866 00:49:23,080 --> 00:49:28,960 Speaker 1: a supernatural explanation. This is ultimately, you know, a natural hypothesis. 867 00:49:29,440 --> 00:49:33,719 Speaker 1: But but it is admittedly an outside possibility. Now, of 868 00:49:33,719 --> 00:49:36,200 Speaker 1: course we're here talking about reasons why you shouldn't just 869 00:49:36,320 --> 00:49:40,520 Speaker 1: jump to the conclusion of a Salurian civilization. But but 870 00:49:40,560 --> 00:49:43,160 Speaker 1: there are also some arguments against it in some of 871 00:49:43,160 --> 00:49:46,560 Speaker 1: the specific events that they look at. For example, if 872 00:49:46,640 --> 00:49:50,759 Speaker 1: you know, maybe the best possibility is this interesting event 873 00:49:50,840 --> 00:49:54,160 Speaker 1: in Earth history, the Paleocene Eocene thermal maximum. More suddenly 874 00:49:54,200 --> 00:49:57,560 Speaker 1: there was there was rapid global warming and UH and 875 00:49:58,000 --> 00:50:01,239 Speaker 1: these in these chemical changes like with carbon isotopes. They 876 00:50:01,560 --> 00:50:07,080 Speaker 1: even put some arguments back against considering UH civilization as 877 00:50:07,239 --> 00:50:10,840 Speaker 1: a cause of this global warming in Earth's history. Because 878 00:50:10,880 --> 00:50:14,400 Speaker 1: they say, look, the kind of global warming caused by 879 00:50:14,400 --> 00:50:18,600 Speaker 1: our civilization is happening in an incredibly rapid fashion over 880 00:50:18,719 --> 00:50:22,359 Speaker 1: just a few hundred years. This actually, though it's it's 881 00:50:22,560 --> 00:50:26,800 Speaker 1: relatively rapid in geologic terms. The the p et M 882 00:50:26,880 --> 00:50:31,359 Speaker 1: actually happened probably over hundreds of thousands of years, which 883 00:50:31,520 --> 00:50:35,719 Speaker 1: which is incredibly slow if you're imagining that civilization was 884 00:50:35,760 --> 00:50:38,320 Speaker 1: the cause of it, right, if you're if you're comparing 885 00:50:38,320 --> 00:50:41,920 Speaker 1: it to the model of of human industrial advancement, it's 886 00:50:41,920 --> 00:50:44,279 Speaker 1: incredibly slow. So there's not only the point that you 887 00:50:44,320 --> 00:50:47,279 Speaker 1: shouldn't just jump to the conclusion of there was a 888 00:50:47,360 --> 00:50:50,080 Speaker 1: law civilization because it feels cool, but like in the 889 00:50:50,160 --> 00:50:52,960 Speaker 1: specific instances they look at, there are some reasons for 890 00:50:53,200 --> 00:50:56,319 Speaker 1: thinking that's probably not true. I don't know, I guess 891 00:50:56,400 --> 00:51:00,839 Speaker 1: unless those civilizations were like just really lazy. I mean, 892 00:51:00,880 --> 00:51:02,959 Speaker 1: you can sort of, you know, pull out your sci 893 00:51:03,000 --> 00:51:05,279 Speaker 1: fi hat and and put it on and come up 894 00:51:05,320 --> 00:51:07,520 Speaker 1: with various ideas of, you know, for why they might 895 00:51:07,560 --> 00:51:09,919 Speaker 1: have been this way. Maybe they were super long lived. Yeah, 896 00:51:09,920 --> 00:51:12,239 Speaker 1: they weren't very ambitious, and they're like this, note, this 897 00:51:12,320 --> 00:51:15,320 Speaker 1: is the right level of industrialization, and we want to, uh, 898 00:51:15,440 --> 00:51:18,040 Speaker 1: we need to keep going at this rate. I don't know, 899 00:51:18,480 --> 00:51:22,279 Speaker 1: they didn't reproduce all that much. I don't know. I 900 00:51:22,320 --> 00:51:26,160 Speaker 1: mean that that's ultimately one of the problems with with imagining, uh, 901 00:51:26,200 --> 00:51:30,400 Speaker 1: you know, other life forms. It's like it's just you know, 902 00:51:30,440 --> 00:51:33,040 Speaker 1: it's you can you can make a case for any 903 00:51:33,120 --> 00:51:37,080 Speaker 1: number of things, um and and try and make it 904 00:51:37,120 --> 00:51:40,239 Speaker 1: fit your your hypothesis. And of course that's not really 905 00:51:40,239 --> 00:51:41,880 Speaker 1: the way to go about it, I mean, not in 906 00:51:42,000 --> 00:51:46,000 Speaker 1: from a scientific perspective, from a sci fi dreaming creative perspective, yeah, 907 00:51:46,080 --> 00:51:50,680 Speaker 1: go for it. Um So, though I guess it does 908 00:51:50,760 --> 00:51:52,320 Speaker 1: kind of come down to the conundrum two at the 909 00:51:52,400 --> 00:51:55,040 Speaker 1: end of the day, like like when does when does 910 00:51:55,040 --> 00:51:59,239 Speaker 1: mere creativity and um and dream weaving become this kind 911 00:51:59,239 --> 00:52:02,080 Speaker 1: of corrupt of our thought and uh and and a 912 00:52:02,120 --> 00:52:05,520 Speaker 1: pollution of our ability to understand our place in the 913 00:52:05,560 --> 00:52:07,960 Speaker 1: world and are where we're going in the future and 914 00:52:07,960 --> 00:52:10,000 Speaker 1: where we were in the past. Well, you know, I 915 00:52:10,080 --> 00:52:13,520 Speaker 1: feel like a thread without maybe intending intending to do so, 916 00:52:13,560 --> 00:52:15,640 Speaker 1: that we've pursued a good bit on this podcast is 917 00:52:16,040 --> 00:52:21,080 Speaker 1: understanding the ideally the difference between your sort of interest 918 00:52:21,120 --> 00:52:25,640 Speaker 1: and imagination and your epistemology. That like that an idea. 919 00:52:25,800 --> 00:52:28,960 Speaker 1: You can like an idea because it's interesting and cool, 920 00:52:29,480 --> 00:52:33,360 Speaker 1: and that doesn't necessarily mean it's true. You know that, 921 00:52:33,600 --> 00:52:36,680 Speaker 1: like that, your your epistemology is probably best to based 922 00:52:36,680 --> 00:52:39,719 Speaker 1: on evidence, and you should be skeptical of things that 923 00:52:39,760 --> 00:52:42,840 Speaker 1: you want to believe because you like them and so forth. 924 00:52:43,120 --> 00:52:45,920 Speaker 1: But it's still totally valid to like, say, be interested 925 00:52:45,960 --> 00:52:49,000 Speaker 1: in the bicameral mind or whatever because it's a fun idea, 926 00:52:49,520 --> 00:52:52,040 Speaker 1: even if you know, you probably accepted as you know, 927 00:52:52,080 --> 00:52:54,759 Speaker 1: there's not a lot of evidence for it, right right, 928 00:52:54,800 --> 00:52:56,400 Speaker 1: You can you can alpoly engage in a number of 929 00:52:56,480 --> 00:52:59,440 Speaker 1: these ideas as as more as art than science, and 930 00:52:59,520 --> 00:53:01,719 Speaker 1: there there's nothing wrong with that. Is when you start 931 00:53:01,880 --> 00:53:04,680 Speaker 1: arguing that your art is science, that's where you can 932 00:53:04,680 --> 00:53:07,719 Speaker 1: get into into some trouble. Um. I was reminded in 933 00:53:07,760 --> 00:53:12,080 Speaker 1: all of this of Carl Sagan's approach to ancient aliens 934 00:53:12,239 --> 00:53:15,200 Speaker 1: and ancient astronauts, particularly in the book that he co 935 00:53:15,320 --> 00:53:20,279 Speaker 1: authored with Joseph Shklovsky Intelligent Life in the Universe. Um. 936 00:53:20,719 --> 00:53:23,640 Speaker 1: The in in this particular book, you know, the the 937 00:53:24,080 --> 00:53:26,720 Speaker 1: examine this idea. They said, okay, here's the speculative idea, 938 00:53:26,800 --> 00:53:29,000 Speaker 1: and we don't have evidence that had ever happened, But 939 00:53:29,040 --> 00:53:31,839 Speaker 1: if it were to have happened, what sorts of specific 940 00:53:31,880 --> 00:53:34,560 Speaker 1: evidence might we look for? And in this case, we're 941 00:53:34,560 --> 00:53:38,359 Speaker 1: talking about signs that are evident in ancient religions and 942 00:53:38,520 --> 00:53:41,800 Speaker 1: uh and so forth. Uh. And I thought that was 943 00:53:41,840 --> 00:53:45,400 Speaker 1: a great treatment of that question. Uh and against Sagan's 944 00:53:45,400 --> 00:53:48,520 Speaker 1: treatment reminds me of the treatment given in this paper 945 00:53:48,560 --> 00:53:51,239 Speaker 1: by these authors. But of course Segand had to come 946 00:53:51,239 --> 00:53:54,760 Speaker 1: back and continue to argue with the ancient alien people 947 00:53:55,320 --> 00:53:57,040 Speaker 1: who were you know, very much going off in their 948 00:53:57,080 --> 00:54:00,960 Speaker 1: own directions, yeah, and pushing pushing art as science, and 949 00:54:01,000 --> 00:54:03,440 Speaker 1: Sagan having to remind them like, no, I love art 950 00:54:03,480 --> 00:54:06,000 Speaker 1: as much as the next guy. But here's how we 951 00:54:06,000 --> 00:54:09,680 Speaker 1: approach this from a scientific perspective. Well, I mean, I 952 00:54:09,680 --> 00:54:12,480 Speaker 1: think the important thing about this stuff, like Sagan's work 953 00:54:12,520 --> 00:54:14,640 Speaker 1: on that or or or the paper we're looking at here, 954 00:54:14,680 --> 00:54:17,360 Speaker 1: is it's good too when you're when you're exploring it 955 00:54:17,440 --> 00:54:20,920 Speaker 1: like a tantalizing and juicy idea. It's a good idea 956 00:54:21,000 --> 00:54:25,160 Speaker 1: to have criteria for what would be good evidence of 957 00:54:25,360 --> 00:54:29,240 Speaker 1: such a thing before you're actually looking at individual evidence 958 00:54:29,280 --> 00:54:31,480 Speaker 1: in cases, because if you look at the evidence first 959 00:54:31,560 --> 00:54:33,920 Speaker 1: and then you try to come up with criteria. You're 960 00:54:33,920 --> 00:54:36,440 Speaker 1: gonna have a tendency to want to fit your criteria 961 00:54:36,480 --> 00:54:39,560 Speaker 1: to whatever evidence you've already got. The cherry picking model 962 00:54:40,480 --> 00:54:43,440 Speaker 1: or what is it the other name of the barn 963 00:54:43,520 --> 00:54:46,520 Speaker 1: wall fallacy or something like that. Remember, the idea is like, 964 00:54:46,560 --> 00:54:48,840 Speaker 1: you know, somebody says, you know, I'm a great shot, 965 00:54:48,880 --> 00:54:50,560 Speaker 1: and so they shoot at the side of a barn 966 00:54:50,800 --> 00:54:52,719 Speaker 1: and then they go up, they walk up to their 967 00:54:52,719 --> 00:54:54,880 Speaker 1: bullet hole, and then they draw a bull's eye perfectly 968 00:54:54,920 --> 00:54:57,319 Speaker 1: around it. That's that's a great point. That's that's a 969 00:54:57,320 --> 00:54:59,480 Speaker 1: great way of looking at it. All Right, Well, I 970 00:54:59,520 --> 00:55:01,400 Speaker 1: guess we're good and go ahead and wrap this episode up. 971 00:55:01,400 --> 00:55:03,400 Speaker 1: But we'd love to hear from everyone out there. I 972 00:55:03,719 --> 00:55:06,000 Speaker 1: love to hear from any doctor who fans who have 973 00:55:07,040 --> 00:55:11,280 Speaker 1: some additional information they want to share about the Silurians 974 00:55:11,320 --> 00:55:15,040 Speaker 1: and various related um species that have popped up in 975 00:55:15,120 --> 00:55:19,360 Speaker 1: that show. And perhaps you have specific thoughts about about 976 00:55:19,600 --> 00:55:22,719 Speaker 1: you know, just this this basic you know view uh 977 00:55:22,760 --> 00:55:27,319 Speaker 1: and what it reveals about humanities uh place on Earth 978 00:55:27,440 --> 00:55:32,320 Speaker 1: right now, and what technological civilization is doing to the planet, 979 00:55:32,680 --> 00:55:35,200 Speaker 1: and just you know, ultimately what kind of a you know, 980 00:55:35,239 --> 00:55:37,880 Speaker 1: a small blip a week signal we may be in 981 00:55:37,920 --> 00:55:41,160 Speaker 1: the future, as opposed to this kind of lasting thing 982 00:55:41,320 --> 00:55:45,520 Speaker 1: that we sometimes imagine that human civilization is. I'm going 983 00:55:45,560 --> 00:55:49,000 Speaker 1: to say, I hope that I'll be optimistic, so I 984 00:55:49,000 --> 00:55:51,719 Speaker 1: hope we do stick around. I hope we attenuate the 985 00:55:51,840 --> 00:55:55,240 Speaker 1: kinds of geologic signal we leave due to climate change 986 00:55:55,239 --> 00:55:57,880 Speaker 1: and chemical alteration of the atmosphere and all you know, 987 00:55:58,040 --> 00:56:01,560 Speaker 1: stuff like that, uh, and heavy metal pollutions and things, 988 00:56:01,640 --> 00:56:04,720 Speaker 1: and that we the signal of our civilization can always 989 00:56:04,760 --> 00:56:07,759 Speaker 1: be charted against the geologic record because of the continuance 990 00:56:07,840 --> 00:56:11,000 Speaker 1: of Doctor Who Seasons. So when we're on the like, 991 00:56:11,080 --> 00:56:13,759 Speaker 1: you know, eventually we'll get into the exponential notation of 992 00:56:13,760 --> 00:56:17,799 Speaker 1: the Doctor Who Seasons. Yeah, yeah, yeah. Well, one day 993 00:56:18,080 --> 00:56:21,360 Speaker 1: some sort of ancient U, or rather some sort of 994 00:56:21,600 --> 00:56:24,640 Speaker 1: far flung future civilization will look back and say, look, 995 00:56:25,320 --> 00:56:27,799 Speaker 1: clearly they knew what they were doing. Uh, they were 996 00:56:27,840 --> 00:56:31,360 Speaker 1: able to do you know, some three million years of 997 00:56:31,400 --> 00:56:34,200 Speaker 1: Doctor Who. Though maybe at a certain point the doctor 998 00:56:34,200 --> 00:56:36,520 Speaker 1: will be a robot and the enemies will be will 999 00:56:36,600 --> 00:56:40,719 Speaker 1: be organics, and I don't know, Yeah, I wonder at 1000 00:56:40,760 --> 00:56:42,759 Speaker 1: what point do we get a robot doctor? I mean, 1001 00:56:42,760 --> 00:56:46,400 Speaker 1: they they're they've only recently really been been been mixing 1002 00:56:46,480 --> 00:56:49,920 Speaker 1: up the casting on that role. Al right, well, let 1003 00:56:49,960 --> 00:56:51,799 Speaker 1: us know in the meantime if you want to listen 1004 00:56:51,800 --> 00:56:53,480 Speaker 1: to other episodes of Stuff to Blow Your Mind, we 1005 00:56:53,520 --> 00:56:55,800 Speaker 1: have core episodes on Tuesdays and Thursdays and the Stuff 1006 00:56:55,840 --> 00:56:59,080 Speaker 1: to Blow your Mind podcast feed. On Monday's we do 1007 00:56:59,120 --> 00:57:02,280 Speaker 1: listener Mail, where we hear from from you, the listeners, 1008 00:57:02,560 --> 00:57:05,520 Speaker 1: and we read your various listener mails, always a good time. 1009 00:57:05,840 --> 00:57:08,879 Speaker 1: On Wednesday's we do a short form artifact or monster fact, 1010 00:57:08,920 --> 00:57:11,200 Speaker 1: and then on Friday's we do Weird How Cinema. That's 1011 00:57:11,239 --> 00:57:14,839 Speaker 1: our time to set aside most serious issues and just 1012 00:57:14,880 --> 00:57:18,200 Speaker 1: talk about a weird film. Huge thanks as always to 1013 00:57:18,240 --> 00:57:21,520 Speaker 1: our excellent audio producer Seth Nicholas Johnson. If you would 1014 00:57:21,520 --> 00:57:23,400 Speaker 1: like to get in touch with us with feedback on 1015 00:57:23,440 --> 00:57:25,560 Speaker 1: this episode or any other, to suggest a topic for 1016 00:57:25,600 --> 00:57:27,640 Speaker 1: the future, or just to say hello, you can email 1017 00:57:27,760 --> 00:57:38,560 Speaker 1: us at contact at stuff to Blow your Mind dot com. 1018 00:57:38,600 --> 00:57:41,080 Speaker 1: Stuff to Blow Your Mind is production of I Heart Radio. 1019 00:57:41,440 --> 00:57:44,360 Speaker 1: For more podcasts for my Heart radios, the iHeart Radio app, 1020 00:57:44,520 --> 00:57:47,240 Speaker 1: Apple Podcasts, or wherever you're listening to your favorite shows. 1021 00:58:00,120 --> 00:58:03,640 Speaker 1: Props had a chat ba