WEBVTT 1 00:00:03.399 --> 00:00:07.719 Welcome to Bedtime Astronomy. Explore the wonders of the cosmos 2 00:00:07.759 --> 00:00:12.279 with our soothing Bedtime Astronomy podcast. Each episode offers a 3 00:00:12.359 --> 00:00:16.320 gentle journey through the stars, planets, and beyond, perfect for 4 00:00:16.399 --> 00:00:20.239 unwinding after a long day. Let's travel through the mysteries 5 00:00:20.239 --> 00:00:22.440 of the universe as you drift off into a peaceful 6 00:00:22.480 --> 00:00:25.920 slumber under the night sky. 7 00:00:26.960 --> 00:00:30.399 Are we alone? I mean, it's the ultimate cosmic question, 8 00:00:30.480 --> 00:00:33.240 isn't it. It really drives so much of our science, 9 00:00:33.359 --> 00:00:34.640 our speculation. 10 00:00:34.240 --> 00:00:38.240 It absolutely does. And for generations of this search for 11 00:00:39.320 --> 00:00:44.079 extraterrestrial technological civilizations etcs as we call them, it's been 12 00:00:44.159 --> 00:00:47.719 fueled by this image of finding something huge. 13 00:00:47.479 --> 00:00:50.840 Right like beings way way beyond us, cosmic architects, maybe 14 00:00:51.200 --> 00:00:55.200 galactic empires, wielding you know, unimaginable power, that kind. 15 00:00:55.119 --> 00:00:58.119 Of thing exactly. That's been the dream. Yet despite all 16 00:00:58.159 --> 00:01:02.119 our efforts, better telescopes, more sense searches, the universe is 17 00:01:02.359 --> 00:01:05.439 just quiet, very quiet. 18 00:01:05.480 --> 00:01:07.760 And that quiet isn't just a letdown. It's a genuine 19 00:01:07.840 --> 00:01:09.879 scientific puzzle, a big one. 20 00:01:09.959 --> 00:01:11.760 It truly is one of the most perplexing. 21 00:01:11.840 --> 00:01:14.519 Really yeah, and that's why we're doing this deep dive today. 22 00:01:14.519 --> 00:01:17.439 We've got some fascinating sources suggesting a really different take, 23 00:01:17.959 --> 00:01:20.359 almost well, almost simple. 24 00:01:20.159 --> 00:01:21.719 A radical idea in its own way. 25 00:01:21.799 --> 00:01:24.959 Totally. We're going to unpack this concept called radical mundanity. 26 00:01:25.319 --> 00:01:28.000 The core idea, maybe the reason we haven't found aliens 27 00:01:28.040 --> 00:01:31.359 isn't because they're super rare or hiding, but because they're 28 00:01:31.400 --> 00:01:35.439 just well ordinary, Yeah, too mundane for us to notice easily. 29 00:01:35.680 --> 00:01:38.200 And we're digging into the work of doctor Robin Corbett here. 30 00:01:38.439 --> 00:01:41.239 His research, it was published on the r arcsoof pre 31 00:01:41.319 --> 00:01:46.760 print server, offers this theoretical framework. Okay, he basically investigates 32 00:01:46.760 --> 00:01:50.480 the chances of finding etcs if we assume this mundanity 33 00:01:50.560 --> 00:01:54.040 idea is correct, and it's vital research because it challenges 34 00:01:54.079 --> 00:01:57.519 that whole super science bias in SETI. 35 00:01:57.319 --> 00:01:59.159 Right, it might change what we should even be looking 36 00:01:59.159 --> 00:02:00.480 for exactly. 37 00:02:00.200 --> 00:02:03.719 And why we're hearing this cosmic silence. 38 00:02:03.920 --> 00:02:06.680 So it all comes back that famous question from doctor 39 00:02:06.799 --> 00:02:09.520 Enrico Fermi way back in nineteen fifty the one we 40 00:02:09.560 --> 00:02:11.639 still can't answer, where is everybody? 41 00:02:11.719 --> 00:02:13.599 That question just cuts right to the heart of it, 42 00:02:13.639 --> 00:02:16.080 doesn't it the Fermi paradox, It really does, and the 43 00:02:16.120 --> 00:02:19.479 paradox itself it's the stark clash between what we expect 44 00:02:19.680 --> 00:02:22.319 and what we actually see, or rather, what we don't see. 45 00:02:22.400 --> 00:02:25.520 The expectation comes from the sheer numbers, right, billions of galaxies, 46 00:02:25.560 --> 00:02:26.719 billions of stars. 47 00:02:26.400 --> 00:02:28.840 In each hundreds of billions. Yeah, and we now know 48 00:02:28.960 --> 00:02:31.560 planets are everywhere, almost every star seems to have them, 49 00:02:31.599 --> 00:02:34.759 and loads are in that Goldilocks zone, the habitable zone. 50 00:02:34.800 --> 00:02:38.960 So statistically, even if life is incredibly rare, multiply that 51 00:02:39.120 --> 00:02:42.360 tiny chance by the gazillions of planets out there. 52 00:02:42.840 --> 00:02:45.280 You should get a galaxy buzzing with life, and a 53 00:02:45.280 --> 00:02:48.400 lot of it should be intelligent technological. Given the billions 54 00:02:48.439 --> 00:02:49.599 of years the universe has been. 55 00:02:49.520 --> 00:02:53.080 Around, plenty of time for civilizations to pop up, grow, 56 00:02:53.599 --> 00:02:56.240 maybe even spread out. We should see sign somewhere. 57 00:02:56.280 --> 00:03:01.280 That's the expectation, but the observation still zero. Absolutely no 58 00:03:01.360 --> 00:03:06.400 definitive proof, no giant alien constructions, no obvious signals, no 59 00:03:07.039 --> 00:03:08.960 you know, take me to your leader moments. 60 00:03:09.000 --> 00:03:09.360 Nothing. 61 00:03:09.520 --> 00:03:13.560 It's this gap, the high probability versus the stark quiet 62 00:03:13.599 --> 00:03:18.159 reality that pushes fields like astrobiology, SETI exoplanet science forward. 63 00:03:18.599 --> 00:03:21.080 We have to figure out why our assumptions don't match 64 00:03:21.080 --> 00:03:21.719 what we're seeing. 65 00:03:21.919 --> 00:03:26.240 If that assumption of like cosmic grandeur keeps getting shot down, 66 00:03:26.599 --> 00:03:28.879 then something fundamental in our thinking must be off. 67 00:03:30.159 --> 00:03:32.280 And for decades, the answers people came up with for 68 00:03:32.360 --> 00:03:35.400 the Fermi paradox tended towards while the sources call them 69 00:03:35.400 --> 00:03:36.520 extreme scenarios. 70 00:03:36.599 --> 00:03:38.560 Okay, yeah, let's touch on those briefly, because this new 71 00:03:38.599 --> 00:03:40.719 idea is supposed to replace them, right exactly. 72 00:03:40.919 --> 00:03:43.680 So, the first big category is that life is just rare, 73 00:03:44.000 --> 00:03:46.960 or it destroys itself. This often involves the idea of 74 00:03:47.000 --> 00:03:47.680 the great filter. 75 00:03:47.960 --> 00:03:52.400 The great filter like some massive hurdle that's almost impossible 76 00:03:52.400 --> 00:03:53.639 for life to get past. 77 00:03:53.680 --> 00:03:56.039 Right, And maybe that filter is behind us. Maybe just 78 00:03:56.080 --> 00:03:59.439 getting life started from non life, or jumping from single 79 00:03:59.520 --> 00:04:03.439 cells to complex creatures like us, maybe that was the 80 00:04:03.479 --> 00:04:07.479 incredibly rare event. If so, hey, maybe we're first or 81 00:04:07.479 --> 00:04:08.439 one of the very few. 82 00:04:08.599 --> 00:04:11.360 That's the optimistic few sort of. Yeah, But the filter 83 00:04:11.400 --> 00:04:12.199 could be ahead of us. 84 00:04:12.159 --> 00:04:17.240 Too, right, that's the more chilling possibility. Maybe civilizations inevitably 85 00:04:17.279 --> 00:04:20.199 hit a wall, runaway climate change, nuclear war, maybe some 86 00:04:20.279 --> 00:04:21.439 kind of out of control AI. 87 00:04:21.720 --> 00:04:24.519 They just snuff themselves out before they can really go interstellar. 88 00:04:24.800 --> 00:04:28.720 Pretty much in that case, advanced civilizations might exist, but 89 00:04:28.759 --> 00:04:31.480 they're either incredibly rare or they just don't last very 90 00:04:31.519 --> 00:04:32.959 long on a cosmic timescale. 91 00:04:33.000 --> 00:04:34.720 Okay, so that's one set of ideas. 92 00:04:34.759 --> 00:04:37.519 What else, then you've got explanations where life is common 93 00:04:37.680 --> 00:04:40.399 but they have reasons to stay quiet. The famous one 94 00:04:40.439 --> 00:04:42.120 is the dark forest hypothesis. 95 00:04:42.439 --> 00:04:46.360 Ah, yeah, from science fiction, but scientists discuss it seriously, 96 00:04:46.399 --> 00:04:48.920 the idea that the universe is dangerous. 97 00:04:48.519 --> 00:04:52.680 Exactly if resources are limited. Announcing your existence could paint 98 00:04:52.720 --> 00:04:55.160 a target on your back. Any new kid on the 99 00:04:55.199 --> 00:04:57.639 block might be seen as a threat by older, more 100 00:04:57.720 --> 00:04:59.120 established civilizations. 101 00:04:59.360 --> 00:05:03.800 So they practic is extreme radio silence, stay hidden to survive. 102 00:05:03.639 --> 00:05:06.560 Right, which implies they also have the tech to detect 103 00:05:06.639 --> 00:05:10.199 others who aren't being quiet and maybe silence them. It 104 00:05:10.279 --> 00:05:12.519 suggests a pretty predatory cosmos. 105 00:05:12.720 --> 00:05:15.399 Yikes. Okay, and the last classic. 106 00:05:15.079 --> 00:05:18.439 One, the zoo hypothesis. This one's a bit more benign, 107 00:05:18.480 --> 00:05:21.480 but still requires immense technological superiority. 108 00:05:21.639 --> 00:05:25.160 They know we're here, but they're just watching, like we're 109 00:05:25.240 --> 00:05:26.920 a cosmic nature preserve sort of. 110 00:05:27.000 --> 00:05:30.279 Yeah, they deliberately avoid contact, maybe following some kind of 111 00:05:30.360 --> 00:05:33.160 prime directive not to interfere with our development. 112 00:05:33.319 --> 00:05:35.720 But again that implies. They're so advanced they can enforce 113 00:05:35.800 --> 00:05:39.519 this across huge distances. They're essentially galactic zoo keepers. 114 00:05:39.600 --> 00:05:42.519 That's the key point. All these traditional explanations. They rely 115 00:05:42.600 --> 00:05:46.800 on extremes, extreme rarity because of a filter, extreme silence, 116 00:05:46.839 --> 00:05:49.759 because of danger, extreme power to run a zoo. 117 00:05:50.120 --> 00:05:54.040 They all assume that if a civilization survives past our stage, 118 00:05:54.199 --> 00:05:58.079 it becomes some kind of cosmic powerhouse, a super science society, 119 00:05:58.120 --> 00:05:59.240 as you said precisely. 120 00:05:59.680 --> 00:06:02.360 But what if that core assumption is wrong. What if 121 00:06:02.399 --> 00:06:05.680 the choice isn't just between cosmic gods and total emptiness. 122 00:06:05.959 --> 00:06:09.959 What if most advanced life is well just a bit 123 00:06:10.000 --> 00:06:12.519 more advanced than us, not godlike at all. 124 00:06:12.759 --> 00:06:16.240 That's the door radical mundanity opens. But first we need 125 00:06:16.279 --> 00:06:19.199 a way to measure advancement, right, ye, a scale. 126 00:06:19.040 --> 00:06:21.319 Right which brings us to Kardashchev. 127 00:06:21.079 --> 00:06:24.480 Exactly to get away from just philosophical handwaving and talk 128 00:06:24.519 --> 00:06:29.240 about physics energy. Doctor Corbett's study uses the Kardashev scale. 129 00:06:29.399 --> 00:06:33.079 It's a classic model from a Soviet astronomer, Nikolai Kardashchev. 130 00:06:32.680 --> 00:06:35.720 And it basically ranks civilizations by how much energy they 131 00:06:35.759 --> 00:06:36.120 can use. 132 00:06:36.199 --> 00:06:39.120 Right, that's the benchmark, that's it purely based on power consumption, 133 00:06:39.319 --> 00:06:43.160 which is a fundamental constraint. And it's a logarithmic scale, remember. 134 00:06:42.839 --> 00:06:46.040 Meaning the jumps between levels are enormous. Not just a 135 00:06:46.079 --> 00:06:49.160 little bit more power, but orders of magnitude. 136 00:06:48.519 --> 00:06:51.360 More astronomical leaps. So let's start at the bottom room. 137 00:06:51.480 --> 00:06:54.920 Type I civilization. This is a civilization that controls all 138 00:06:54.959 --> 00:06:57.000 the energy available on its home planet. 139 00:06:57.199 --> 00:07:00.480 So we're talking weather control, tapping all gethermal wind, solar, 140 00:07:01.480 --> 00:07:06.040 maybe advanced fusion power, basically managing the entire planet's energy budget. 141 00:07:06.079 --> 00:07:09.480 Total planetary energy management. Yeah, something like ten to the 142 00:07:09.519 --> 00:07:13.360 sixteen watts. Humanity, for context, is still climbing towards that. 143 00:07:13.720 --> 00:07:17.399 Carl Sagan estimated US around point seven maybe point seventy three. 144 00:07:17.519 --> 00:07:18.879 Now we're not quite there yet. 145 00:07:18.959 --> 00:07:21.720 Okay, So Type I is planetary mastery. What's type two? 146 00:07:21.920 --> 00:07:25.879 Type two civilization, Now you take a colossal jump. This 147 00:07:25.959 --> 00:07:30.319 civilization harnesses the total energy output of its host star. 148 00:07:30.480 --> 00:07:33.120 It's entire star like our sun. 149 00:07:33.319 --> 00:07:35.560 Yep, for a star like our sun, that's about ten 150 00:07:35.600 --> 00:07:38.480 to the twenty six watts. That's ten billion times more 151 00:07:38.560 --> 00:07:41.360 energy than a Type I civilization uses. This is where 152 00:07:41.399 --> 00:07:43.079 you get into proper superscience man. 153 00:07:43.160 --> 00:07:45.120 The classic image here is the dice in sphere, or 154 00:07:45.160 --> 00:07:48.360 maybe a dice and swarm. These massive structures built around 155 00:07:48.399 --> 00:07:50.319 the star to capture all its light and heat. 156 00:07:50.480 --> 00:07:53.519 That's the theoretical mechanism. Yes, building something on that scale, 157 00:07:53.560 --> 00:07:57.199 it boggles the mind. Structures bigger than planet's completely enclosing 158 00:07:57.240 --> 00:07:57.560 a star. 159 00:07:57.800 --> 00:08:01.800 And the crucial point for detection is they couldn't hide this, 160 00:08:01.920 --> 00:08:03.279 could they, even if they wanted to. 161 00:08:03.639 --> 00:08:07.519 That's the argument physics demands that energy conversion creates waste 162 00:08:07.519 --> 00:08:12.399 heat thermodynamics. Even a super efficient Type two civilization capturing 163 00:08:12.439 --> 00:08:14.000 nearly all its stars light. 164 00:08:13.920 --> 00:08:17.399 Would still radiate heat, waste heat exactly. 165 00:08:17.000 --> 00:08:19.360 So instead of seeing a normal star, we'd see something 166 00:08:19.439 --> 00:08:23.160 dimmer invisible light, but with this huge unnatural spike in 167 00:08:23.199 --> 00:08:24.360 the infrared. 168 00:08:23.879 --> 00:08:27.439 Spectrum, like a giant heat signature where a star should be. Yeah, 169 00:08:27.480 --> 00:08:29.040 something that screams. 170 00:08:28.879 --> 00:08:34.480 Artificial, unmistakably artificial, a massive blob of mid infrared radiation. 171 00:08:35.159 --> 00:08:38.519 If even one Type two civilization existed in our galaxy 172 00:08:38.519 --> 00:08:40.159 and had been around for a while. 173 00:08:40.080 --> 00:08:42.639 We should have spotted that heat signature with our infrared 174 00:08:42.679 --> 00:08:44.559 surveys like Wyser Spitzer. 175 00:08:44.679 --> 00:08:47.240 We should have the fact that we've found basically no 176 00:08:47.399 --> 00:08:51.360 really convincing candidates for these megastructures. That is the Fermi 177 00:08:51.399 --> 00:08:53.720 paradox in action, it deepens the mystery. 178 00:08:53.799 --> 00:08:57.000 Okay, so Type two is stellar mastery, and then there's 179 00:08:57.000 --> 00:08:57.720 type three. 180 00:08:57.600 --> 00:09:00.840 Type three civilization. This is almost abstract. They harness the 181 00:09:00.919 --> 00:09:03.200 energy of their entire home galaxy. 182 00:09:02.799 --> 00:09:04.679 The whole galaxy, billions of. 183 00:09:04.600 --> 00:09:09.519 Stars, billions of stars, galactic overlords. Essentially, if the type 184 00:09:09.600 --> 00:09:12.960 three existed, it wouldn't just be detectable, the entire galaxy 185 00:09:13.000 --> 00:09:16.519 would look fundamentally different. Clearly managed or engineers. 186 00:09:16.159 --> 00:09:18.639 In our galaxy doesn't look like that at. 187 00:09:18.519 --> 00:09:22.200 All, not even close. So the clear absence of type 188 00:09:22.200 --> 00:09:26.120 two and type three civilizations is what really forces this rethink. 189 00:09:26.720 --> 00:09:30.240 If the super powerful aliens aren't there, what's left. 190 00:09:30.080 --> 00:09:32.360 Which brings us back to this idea mundanity. 191 00:09:32.679 --> 00:09:35.799 Right, if the extremes, extreme rarity or extreme power don't 192 00:09:35.840 --> 00:09:39.759 fit the observations, maybe we've been aiming too high, overestimating 193 00:09:39.759 --> 00:09:41.759 the technological ceiling for most life. 194 00:09:41.799 --> 00:09:46.120 Okay, let's really unpack this radical mundanity that doctor Corbett proposes. 195 00:09:46.360 --> 00:09:48.320 This is where it gets really interesting, kind of flips 196 00:09:48.360 --> 00:09:48.759 the script. 197 00:09:48.799 --> 00:09:52.240 The basic idea is surprisingly simple maybe the silence is 198 00:09:52.279 --> 00:09:54.840 explained if the galaxy just contains a modest number of 199 00:09:54.879 --> 00:09:59.799 technological civilizations, and crucially, their technology level is only modestly 200 00:09:59.840 --> 00:10:02.840 highhigher than ours, not Type two or three, maybe Type one, 201 00:10:02.919 --> 00:10:05.080 or just a bit past it like Type one point 202 00:10:05.080 --> 00:10:08.480 one exactly. Their technological ceiling is just lower than we've 203 00:10:08.519 --> 00:10:11.200 often assumed. They never reach the star harnessing stage. 204 00:10:11.440 --> 00:10:15.320 And Corbett breaks this mundanity down into two parts, right, 205 00:10:15.679 --> 00:10:16.440 two dimensions. 206 00:10:16.600 --> 00:10:20.840 Yes, two key aspects working together. First is technological mundanity. 207 00:10:21.120 --> 00:10:23.279 This is about the physical and practical limits. 208 00:10:23.440 --> 00:10:26.039 So maybe etcs just don't make the breakthroughs needed for 209 00:10:26.120 --> 00:10:29.360 type two. Or maybe it's just too expensive or resource intensive. 210 00:10:29.519 --> 00:10:33.320 Precisely, think about building a dice in sphere. The sheer 211 00:10:33.360 --> 00:10:37.919 amount of material, the energy investment, the logistical nightmare. Maybe 212 00:10:37.919 --> 00:10:41.000 it's just fundamentally beyond the reach of a civilization confined 213 00:10:41.000 --> 00:10:43.879 to its home planet's resources, no matter how smart they are. 214 00:10:44.159 --> 00:10:48.840 So achieving Type I planetary mastery, that's achievable. It solves 215 00:10:48.879 --> 00:10:51.519 local problems, ensure sustainability on their world. 216 00:10:51.600 --> 00:10:55.759 Right they survive, they thrive, perhaps become stable. But that 217 00:10:55.879 --> 00:10:59.799 leap from managing a planet's energy to managing a star's energy. 218 00:11:00.840 --> 00:11:02.679 Maybe that gap is just too vast. 219 00:11:02.519 --> 00:11:05.080 Kind of technological cul de sac around TYPEOD. 220 00:11:04.720 --> 00:11:06.200 That's a good way to put it. Maybe there are 221 00:11:06.320 --> 00:11:10.559 fundamental physics limitations or material science barriers, or simply the 222 00:11:10.639 --> 00:11:14.639 economics are astronomical and make it unfeasible. Stellar engineering stay 223 00:11:14.679 --> 00:11:15.960 science fiction for them, so. 224 00:11:15.879 --> 00:11:19.960 Their tech would be recognizable to us in principle, clean fusion, 225 00:11:20.360 --> 00:11:24.799 maybe efficient interplanetary travel within their own system, advanced computing, 226 00:11:25.399 --> 00:11:27.080 but still planetary. 227 00:11:26.519 --> 00:11:29.480 And scale exactly, still bound by the resources and energy 228 00:11:29.519 --> 00:11:33.559 available on one world. And the second dimension is numerical mundanity. 229 00:11:33.679 --> 00:11:36.399 This is about how many there are, right, The hypothesis 230 00:11:36.440 --> 00:11:39.120 suggests there just aren't that many etcs out there, not 231 00:11:39.320 --> 00:11:44.240 millions densely packed, but also not zero, just a modest number, a. 232 00:11:44.240 --> 00:11:49.519 Handful, dozens, maybe scattered across the huge expanse of the galaxy. 233 00:11:49.120 --> 00:11:52.000 Something like that. Enough to exist, but few enough and 234 00:11:52.080 --> 00:11:54.679 far enough apart that the chances of us stumbling across 235 00:11:54.679 --> 00:11:57.600 them or them finding us become pretty low, especially. 236 00:11:57.279 --> 00:12:01.279 If they're not building giant, flashy megastructure or shouting with 237 00:12:01.360 --> 00:12:02.320 powerful beacons. 238 00:12:02.480 --> 00:12:05.279 That's the key connection. If they're only modestly advanced and 239 00:12:05.360 --> 00:12:09.159 modestly numerous. We're not looking for cosmic gods beaming signals 240 00:12:09.200 --> 00:12:13.399 across thousands of light years. We're looking for effectively Type 241 00:12:13.440 --> 00:12:16.960 I planetary engineers quietly managing their infrastructure. 242 00:12:17.159 --> 00:12:19.480 It changes the whole search paradigm completely. 243 00:12:19.559 --> 00:12:23.799 The contrast is stark. We've been searching for galactic scale disruptions, 244 00:12:23.840 --> 00:12:27.519 signs of super science. Radical mundanity says we should be 245 00:12:27.600 --> 00:12:28.840 looking for quiet. 246 00:12:28.519 --> 00:12:34.000 Competence civilizations that are successful, stable, but ultimately limited by 247 00:12:34.000 --> 00:12:37.320 the physics of distance and energy on a galactic scale. 248 00:12:37.399 --> 00:12:40.080 They just don't have the capability or perhaps the motivation 249 00:12:40.320 --> 00:12:42.159 to make a huge cosmic splash. 250 00:12:42.320 --> 00:12:46.720 Okay, so if we accept this premise modestly advanced, modestly 251 00:12:46.840 --> 00:12:50.399 numerous to the rough, what does that actually mean for 252 00:12:50.480 --> 00:12:54.480 their ability to, say, explore the galaxy or for us 253 00:12:54.519 --> 00:12:57.399 to detect them. It implies constraints absolutely. 254 00:12:57.440 --> 00:13:00.559 If they're mundane, they're still fundamentally bound by physics and 255 00:13:00.600 --> 00:13:03.720 resource limitations, much like us. Their ability to act on 256 00:13:03.759 --> 00:13:06.519 a galactic scale is severely curtailed by their Type I 257 00:13:06.720 --> 00:13:09.679 maybe type one point one energy budget. 258 00:13:09.399 --> 00:13:11.080 And these constraints are the reason. 259 00:13:10.879 --> 00:13:14.120 For this silent precisely, a civilization that hasn't cracked stellar 260 00:13:14.200 --> 00:13:17.759 level energy, can't easily conquer or communicate across the vast 261 00:13:17.799 --> 00:13:18.639 interstellar voids. 262 00:13:18.679 --> 00:13:21.440 Let's break down those constraints. Corvett talks about constraint one 263 00:13:21.519 --> 00:13:24.759 galactic conquest via robotics, even if they wanted to expand, 264 00:13:24.759 --> 00:13:26.759 maybe for science or survival. 265 00:13:26.559 --> 00:13:30.039 The sheer scale of the galaxy is a killer app basically, 266 00:13:30.840 --> 00:13:33.360 even for a civilization a bit ahead of us, say 267 00:13:33.720 --> 00:13:35.679 type one point one or one point. 268 00:13:35.440 --> 00:13:39.600 Two, sending probes out like von Neumann, probes that replicate themselves. 269 00:13:39.679 --> 00:13:42.440 That's often proposed as a solution to the Fermi paradox. 270 00:13:42.440 --> 00:13:46.279 Why haven't self replicating probes filled the galaxy? But launching 271 00:13:46.279 --> 00:13:49.799 and sustaining such a program requires unbelievable amounts of energy 272 00:13:49.799 --> 00:13:52.759 and resources, far beyond a planetary budget. 273 00:13:52.840 --> 00:13:56.279 Think about our own Voyager probes, huge effort decades later, 274 00:13:56.320 --> 00:13:58.799 they've barely left the Solar System in galactic. 275 00:13:58.399 --> 00:14:01.519 Terms exactly, and talk about maybe sending a probe to 276 00:14:01.519 --> 00:14:04.879 Alpha Centauri just over four light years away, and the 277 00:14:04.960 --> 00:14:08.200 engineering challenges are already immense. The energy costs are huge. 278 00:14:08.320 --> 00:14:11.679 Now scale that up. Trying to explore thousands, maybe millions 279 00:14:11.679 --> 00:14:13.960 of star systems with robotic. 280 00:14:13.639 --> 00:14:16.759 Probes, the cumulative energy needed to build them, launch them, 281 00:14:16.799 --> 00:14:20.759 accelerate them to reasonable speeds, maybe decelerate them, ensure they 282 00:14:20.799 --> 00:14:24.320 work for centuries or millennia. It just likely exceeds the 283 00:14:24.440 --> 00:14:26.840 energy income of a planet bound civilization. 284 00:14:27.399 --> 00:14:30.919 So the sheer vastness of space remains a fundamental barrier. 285 00:14:31.200 --> 00:14:33.559 Interstellar travel is hard even for them. 286 00:14:33.879 --> 00:14:37.840 It seems plausible, yes, the logistics, the energy cost. It 287 00:14:37.879 --> 00:14:40.799 acts like a natural break on galactic expansion for any 288 00:14:40.879 --> 00:14:43.679 civilization that hasn't achieved type two power levels. 289 00:14:43.960 --> 00:14:48.879 Okay, so widespread physical travel or colonization is probably out 290 00:14:48.879 --> 00:14:53.840 for mundane civilizations. What about communication that brings us to 291 00:14:53.919 --> 00:14:56.440 constraint too high powered beacons? 292 00:14:56.639 --> 00:14:59.639 Yeah, this is a big one for SETI. For decades, 293 00:14:59.679 --> 00:15:04.200 the hope was we'd detect a deliberate, powerful signal, a beacon. 294 00:15:03.960 --> 00:15:06.720 Something designed to be noticed across the galaxy shouting we 295 00:15:06.759 --> 00:15:12.200 are here, like the Wow signal. Maybe, though that wasn't confirmed, right. 296 00:15:12.159 --> 00:15:14.960 But think about the energy needed to run such a beacon. 297 00:15:15.240 --> 00:15:17.559 To make it powerful enough to cross hundreds or thousands 298 00:15:17.559 --> 00:15:20.519 of light years and still be detectable above the background noise, 299 00:15:20.519 --> 00:15:20.879 I have to. 300 00:15:20.960 --> 00:15:23.480 Keep it running for a long time right, millennia, millions 301 00:15:23.480 --> 00:15:25.960 of years. You don't know when someone might be listening exactly. 302 00:15:26.080 --> 00:15:29.320 The total energy expenditure would be astronomical. We're talking about 303 00:15:29.440 --> 00:15:33.039 potentially diverting a significant fraction of a type by civilization's 304 00:15:33.200 --> 00:15:36.480 entire energy budget just to maintain this speculative shout into 305 00:15:36.519 --> 00:15:36.879 the void. 306 00:15:37.159 --> 00:15:40.799 Would a mundane civilization see that as a sensible use 307 00:15:40.840 --> 00:15:41.600 of resources. 308 00:15:42.159 --> 00:15:47.360 Probably not. It seems inefficient, wasteful. Even they'd likely have 309 00:15:47.639 --> 00:15:52.519 very efficient communication within their own solar system, focused laser beams, 310 00:15:52.639 --> 00:15:56.039 maybe tight microwave links, perhaps even quantum communication if they've 311 00:15:56.039 --> 00:15:57.279 cracked that stuff. 312 00:15:56.960 --> 00:15:59.279 That doesn't spray energy wastefully across. 313 00:15:58.919 --> 00:16:03.200 The galaxy exactly. So, the lack of obvious powerful beacons 314 00:16:03.279 --> 00:16:05.960 isn't necessarily proof no one's out there. It might just 315 00:16:06.039 --> 00:16:09.559 be a sign of their well, they're mundanity, their practicality. 316 00:16:09.600 --> 00:16:13.360 They don't have the energy to spare for galactic vanity projects. 317 00:16:13.519 --> 00:16:16.720 Okay, So if they're not physically exploring widely and they're 318 00:16:16.720 --> 00:16:20.639 not shouting with powerful beacons, how could we possibly detect them? 319 00:16:20.720 --> 00:16:24.120 That leads to constraint three weak techno signatures. 320 00:16:24.240 --> 00:16:26.360 This is really the crux of it for future searches. 321 00:16:26.799 --> 00:16:29.919 If mundane etcs exist, the only signs were likely to 322 00:16:29.960 --> 00:16:31.879 detect are their unintentional signals. 323 00:16:31.879 --> 00:16:36.039 Their leakage radiation, like the accidental electromagnetic noise from their technology, 324 00:16:36.120 --> 00:16:37.000 is leaking out into. 325 00:16:36.879 --> 00:16:41.200 Space precisely the hum of their civilization, Their equivalent of 326 00:16:41.200 --> 00:16:45.960 our old TV broadcasts, radar signals, maybe planetary defense grids, 327 00:16:46.080 --> 00:16:51.159 power transmission, whatever em noiser daily lives generate that isn't 328 00:16:51.159 --> 00:16:52.159 perfectly contained. 329 00:16:52.440 --> 00:16:55.320 But you mentioned earlier, even our leakage is getting weaker, 330 00:16:55.360 --> 00:16:57.279 isn't it as technology gets more efficient? 331 00:16:57.399 --> 00:16:59.759 It is, And that's a critical point in Corvette's argument. 332 00:16:59.799 --> 00:17:04.440 Are our early radio and TV was broadcast omnidirectionally, very leaky, 333 00:17:04.640 --> 00:17:08.640 relatively strong signals. But now we use fiber optics, which 334 00:17:08.720 --> 00:17:12.680 keeps the signal contained. We use focus satellite beams, low power, 335 00:17:13.000 --> 00:17:15.279 We're moving to spread spectrum techniques. 336 00:17:15.359 --> 00:17:18.519 Laser comms all much harder to detect from light years. 337 00:17:18.359 --> 00:17:21.559 Away, much harder so in etc. That's even just say 338 00:17:21.640 --> 00:17:24.480 a century or two ahead of us. Technologically, they've likely 339 00:17:24.559 --> 00:17:28.279 already transitioned to these highly efficient, very low leakage methods. 340 00:17:28.359 --> 00:17:31.880 They've managed your data with incredible sophistication. Maybe using technologies 341 00:17:31.920 --> 00:17:33.839 we haven't even thought of yet, But the result is 342 00:17:34.920 --> 00:17:36.480 less accidental noise escaping. 343 00:17:36.640 --> 00:17:40.039 Almost certainly, their whisper would be incredibly faint by the 344 00:17:40.039 --> 00:17:42.359 time it crossed interstellar distances to reach us. 345 00:17:42.599 --> 00:17:46.759 So detecting that faint leakage that's a whole different ballgame 346 00:17:46.839 --> 00:17:48.640 compared to searching for a beacon. 347 00:17:48.559 --> 00:17:53.279 Hugely different. It needs incredibly sensitive instruments, massive collecting areas, 348 00:17:53.400 --> 00:17:58.400 sophisticated signal processing to dig that tiny artificial noise out 349 00:17:58.440 --> 00:18:01.440 from the natural cosmic status. And you need to stare 350 00:18:01.480 --> 00:18:03.799 at individual star systems for a long time. 351 00:18:04.039 --> 00:18:06.359 So the silence we hear now might not be an 352 00:18:06.359 --> 00:18:09.039 empty universe. It might just be the sound of our 353 00:18:09.039 --> 00:18:12.920 own current technological limitations. We can't hear the whispers yet. 354 00:18:12.960 --> 00:18:16.680 That's the essence of the radical mundanity explanation for the silence. 355 00:18:16.880 --> 00:18:19.839 It's a problem of signal strength and detection threshold, not 356 00:18:19.920 --> 00:18:21.000 necessarily absence. 357 00:18:21.240 --> 00:18:24.799 Okay, So Corbett took this principle, these constraints and use 358 00:18:24.880 --> 00:18:27.200 them to test the different possibilities for what the galaxy 359 00:18:27.240 --> 00:18:28.079 might actually look like. 360 00:18:28.240 --> 00:18:30.640 Right, He set up a kind of logical framework based 361 00:18:30.640 --> 00:18:33.680 on those two variables. Number of civilizations many are few 362 00:18:34.119 --> 00:18:37.519 and their tech level high Type three or mundane Type 363 00:18:37.519 --> 00:18:40.960 I ish. That gives four possible scenarios. 364 00:18:40.480 --> 00:18:44.599 And by applying the constraints no obvious megastructures, the difficulty 365 00:18:44.599 --> 00:18:47.519 of beacons, the faintness of leakage, he could basically rule 366 00:18:47.559 --> 00:18:48.920 out three of them exactly. 367 00:18:49.039 --> 00:18:53.319 Let's walk through the eliminations. The first two are fairly straightforward, 368 00:18:53.480 --> 00:18:57.039 based on the lack of super science evidence. Hypothesis one 369 00:18:57.480 --> 00:19:02.440 many civilizations AMD very high technological level false. If there 370 00:19:02.480 --> 00:19:05.319 were many Type two or three civilizations, the galaxy would 371 00:19:05.319 --> 00:19:08.960 be obviously teeming with astro engineering projects and their heat signatures. 372 00:19:09.400 --> 00:19:11.200 It isn't simple enough. What's next. 373 00:19:11.279 --> 00:19:15.440 Hypothesis two very few civilizations A and D very high 374 00:19:15.519 --> 00:19:19.079 technological level also seems false. Even just one or two 375 00:19:19.119 --> 00:19:21.839 Type two civilizations, if they've been around for millions of years, 376 00:19:21.839 --> 00:19:24.359 should have had enough time and power to become detectable. 377 00:19:24.559 --> 00:19:28.240 They're waste heat, maybe probes, something should be visible somewhere. 378 00:19:28.440 --> 00:19:30.599 The silence argues against this too, right. 379 00:19:30.640 --> 00:19:34.519 No supercivilizations, whether common or rare, so the answer must 380 00:19:34.559 --> 00:19:37.640 lie with mundane technology. But there are two options there. 381 00:19:37.680 --> 00:19:40.720 Now it gets interesting. Hypothesis three many civilizations A and 382 00:19:40.799 --> 00:19:44.240 d mundane technological level. Corbett argues this one is also 383 00:19:44.400 --> 00:19:44.920 likely false. 384 00:19:44.960 --> 00:19:47.920 Wait, why if they're mundane, they're quiet, But if there 385 00:19:47.920 --> 00:19:50.400 are lots of them, wouldn't the combined whispers add up. 386 00:19:50.519 --> 00:19:53.880 Wouldn't we eventually detect something just by sheer numbers. 387 00:19:54.039 --> 00:19:57.920 That's the critical point. If there were truly many, maybe 388 00:19:57.920 --> 00:20:01.400 thousands or millions, scattered through the galaxy, even if each 389 00:20:01.480 --> 00:20:05.400 one only leaks a tiny bit of radiation, the cumulative 390 00:20:05.440 --> 00:20:10.880 effect becomes significant. Statistically, some should be relatively close by, close. 391 00:20:10.680 --> 00:20:13.480 Enough for even their faint leakage to be detectable with 392 00:20:13.559 --> 00:20:15.920 our current or near future capabilities. 393 00:20:16.079 --> 00:20:20.000 Plausibly, yes, over the decade SETI has been active. If 394 00:20:20.000 --> 00:20:23.519 the galaxy was densely populated with Type BI civilizations, we 395 00:20:23.599 --> 00:20:27.160 probably should have picked up some persistent, structured, artificial looking 396 00:20:27.200 --> 00:20:30.359 noise by now, even if it was weak. The profound 397 00:20:30.480 --> 00:20:34.359 lack of such signals suggests the population density isn't that high. 398 00:20:34.680 --> 00:20:37.640 So the silence is just because they're individually quiet. It's 399 00:20:37.640 --> 00:20:39.640 also because there aren't that many of them overall. 400 00:20:39.799 --> 00:20:42.920 That's the inference. The lack of any compelling signal, beacon 401 00:20:43.119 --> 00:20:47.160