1 00:00:00,160 --> 00:00:03,279 Speaker 1: Imagine looking up into the night sky, you know, past 2 00:00:03,319 --> 00:00:06,200 the constellations, past the Milky Way, and just trying to 3 00:00:06,200 --> 00:00:08,000 wrap your head around the idea that what you don't 4 00:00:08,000 --> 00:00:10,839 see is far, far more abundant than what you do. 5 00:00:11,080 --> 00:00:12,439 Speaker 2: It's a chilling thought, isn't it. 6 00:00:12,439 --> 00:00:15,640 Speaker 1: It really is. We are talking about entire worlds, planets, 7 00:00:15,679 --> 00:00:19,719 you know, ranging from smaller than Mars to way bigger 8 00:00:19,719 --> 00:00:25,760 than Jupiter, just hurtling through the vacuum, dark, silent, completely 9 00:00:25,839 --> 00:00:27,399 unbound by any star. 10 00:00:27,679 --> 00:00:30,559 Speaker 2: And that's the real paradox here. The largest population of 11 00:00:30,600 --> 00:00:33,240 planetary mass objects in our galaxy might just be the 12 00:00:33,240 --> 00:00:36,960 one we can't actually see. These gravitational no bands, which 13 00:00:37,000 --> 00:00:39,719 is a term Stragarian as team used, could number in 14 00:00:39,759 --> 00:00:42,960 the millions, or even trillions, or even trillions. Yeah, just 15 00:00:43,039 --> 00:00:45,359 sailing through our galactic neighborhood as we speak. 16 00:00:45,560 --> 00:00:48,719 Speaker 1: Welcome to Thrilling Threads, where we take your sources and 17 00:00:48,799 --> 00:00:52,079 unpack the biggest, most mind bending ideas in the universe. 18 00:00:52,439 --> 00:00:54,880 And today we are absolutely diving into the mystery of 19 00:00:54,920 --> 00:00:58,840 these cosmic wanderers. Our listener was curious about this unseen fleet, 20 00:00:58,960 --> 00:01:01,560 you know, how they exist, the danger they pose, and 21 00:01:01,600 --> 00:01:05,239 this shocking potential for them to harbor life. 22 00:01:05,480 --> 00:01:08,079 Speaker 2: So our mission today is to really get into the 23 00:01:08,159 --> 00:01:11,560 hard science behind these nomads, and I think we need 24 00:01:11,599 --> 00:01:16,040 to start with a really clear definition when we say 25 00:01:16,599 --> 00:01:20,439 rogue planet or free floating planet FFP. For sure, what 26 00:01:20,519 --> 00:01:23,840 are we talking about. We're talking about a planetary mass 27 00:01:23,879 --> 00:01:28,200 object that is gravitationally unbound. Simply put, they are planets 28 00:01:28,239 --> 00:01:29,920 floating completely alone in the dark. 29 00:01:30,000 --> 00:01:32,200 Speaker 1: They've either been kicked out of their home system or 30 00:01:32,319 --> 00:01:34,239 maybe they just formed that way exactly. 31 00:01:34,799 --> 00:01:36,560 Speaker 2: And before we go any further, let's just touch on 32 00:01:36,599 --> 00:01:40,480 the sheer scale of this. Oh, because the numbers they're dizzying. 33 00:01:40,519 --> 00:01:44,200 They really are based on microlensing data, which we'll get into. 34 00:01:44,400 --> 00:01:46,959 Strigari and his colleague suggests there could be up to 35 00:01:48,280 --> 00:01:50,719 ten to the power of five, So one hundred thousand 36 00:01:50,799 --> 00:01:54,519 compact objects for every single main sequence star, one hundred. 37 00:01:54,280 --> 00:01:57,879 Speaker 1: Thousand planets for every sun. And these are objects bigger 38 00:01:57,879 --> 00:01:59,280 than Pluto, right. 39 00:01:59,120 --> 00:02:02,040 Speaker 2: Think about that first time, The Milky Way has what 40 00:02:02,200 --> 00:02:05,159 two hundred billion stars. At least you multiply that by 41 00:02:05,159 --> 00:02:09,439 one hundred thousand. The space between the stars isn't empty, 42 00:02:10,120 --> 00:02:15,680 it's intensely populated by trillions of these silent, dark worlds, 43 00:02:16,120 --> 00:02:19,240 a vast unseen fleet. That's the reality we have to 44 00:02:19,280 --> 00:02:19,719 grapple with. 45 00:02:19,800 --> 00:02:22,280 Speaker 1: Okay, let's unpack that. That is an enormous plan. We're 46 00:02:22,280 --> 00:02:26,639 talking about worlds that are essentially pitch black. How, I mean, 47 00:02:26,840 --> 00:02:29,240 how on earth do you even begin to find a 48 00:02:29,439 --> 00:02:33,560 dark object against the black backdrop of space? The challenge 49 00:02:33,960 --> 00:02:36,039 seems almost impossible. 50 00:02:36,120 --> 00:02:39,159 Speaker 2: It's incredibly difficult because there's no traditional light source. Road 51 00:02:39,240 --> 00:02:42,360 planets are invisible to normal telescopes, they don't have a 52 00:02:42,400 --> 00:02:44,800 star to reflect light, and they're too cold and small 53 00:02:44,840 --> 00:02:46,960 to radiate much heat on their own, not like a 54 00:02:46,960 --> 00:02:48,280 star or even a brown dwarf. 55 00:02:48,400 --> 00:02:50,439 Speaker 1: So you need a completely different method. 56 00:02:50,199 --> 00:02:54,280 Speaker 2: A completely non traditional method. Yeah, and thankfully Einstein give 57 00:02:54,360 --> 00:02:54,960 is the tool. 58 00:02:54,759 --> 00:02:57,400 Speaker 1: For it, and that brings us right to gravitational microlensing. 59 00:02:57,599 --> 00:03:00,000 So this is the key, right, it's really the only 60 00:03:00,080 --> 00:03:02,560 liable technique we have right now for finding these things. 61 00:03:02,879 --> 00:03:05,560 Speaker 2: It is it all comes down to a core principle 62 00:03:05,599 --> 00:03:11,199 of general relativity. Mass warps space time. So when a 63 00:03:11,319 --> 00:03:14,199 massive object, in this case our rogue planet, which we 64 00:03:14,280 --> 00:03:18,360 call the lens, passes almost perfectly in line between us 65 00:03:18,719 --> 00:03:21,960 and a distant star, the source star right exactly. The 66 00:03:22,039 --> 00:03:26,120 rogue planet's gravity acts like a temporary magnifying glass. 67 00:03:25,759 --> 00:03:28,159 Speaker 1: So it actually bends the light from that background star, 68 00:03:28,400 --> 00:03:31,479 focuses it and makes it look brighter from our perspective. 69 00:03:31,639 --> 00:03:35,599 Speaker 2: Precisely, we see a temporary brightening, a little anomaly in 70 00:03:35,639 --> 00:03:38,560 the star's light curve. And the beauty of this is 71 00:03:38,560 --> 00:03:41,199 that the duration of that brightening and how bright it 72 00:03:41,240 --> 00:03:44,000 gets that's directly linked to the mass of the unseen 73 00:03:44,039 --> 00:03:45,400 planet the past in front. 74 00:03:45,199 --> 00:03:47,639 Speaker 1: And the event has to be incredibly brief, I'd imagine. 75 00:03:47,680 --> 00:03:49,560 I mean, this thing is just flying by. It's not 76 00:03:49,599 --> 00:03:50,639 in a stable orbit. 77 00:03:50,800 --> 00:03:53,599 Speaker 2: That's the catch. It's super brief, maybe a few hours, 78 00:03:53,599 --> 00:03:55,719 a few days at most. You have to be looking 79 00:03:55,759 --> 00:03:58,039 at the exact right place at the exact right time. 80 00:03:57,879 --> 00:04:01,479 Speaker 1: Which means you need automated systems scan millions of stars 81 00:04:01,639 --> 00:04:04,240 all the time looking for these tiny blips. 82 00:04:04,000 --> 00:04:07,120 Speaker 2: Right, and this high cadence monitoring is what led to 83 00:04:07,159 --> 00:04:09,919 some staggering initial results. Let's go back to that twenty 84 00:04:09,960 --> 00:04:13,680 eleven study from the MOA and OGL collaborations, the one 85 00:04:13,759 --> 00:04:14,719 led by Suomi. 86 00:04:14,560 --> 00:04:16,040 Speaker 1: That was the one that really opened the flood gates, 87 00:04:16,079 --> 00:04:16,480 wasn't it. 88 00:04:16,480 --> 00:04:20,680 Speaker 2: It really was They monitored fifty million stars fifty million, 89 00:04:21,240 --> 00:04:23,920 and they found about four hundred and seventy four microlensing 90 00:04:23,959 --> 00:04:27,560 events in total. But the key was ten of those 91 00:04:28,040 --> 00:04:32,079 were extremely brief and crucially they showed no sign of 92 00:04:32,120 --> 00:04:34,680 a host star anywhere nearby ten events. 93 00:04:34,759 --> 00:04:37,560 Speaker 1: And from those ten lonely events, what did they extrapolate 94 00:04:37,600 --> 00:04:38,879 about the galactic population? 95 00:04:39,160 --> 00:04:41,839 Speaker 2: This is what blew everyone away. Based on just those 96 00:04:41,879 --> 00:04:45,720 ten events, they calculated that statistically there are nearly two 97 00:04:45,800 --> 00:04:49,720 jupiter mass rogue planets for every single star in the Milky. 98 00:04:49,399 --> 00:04:50,879 Speaker 1: Way, two jupiters for every sin. 99 00:04:51,040 --> 00:04:54,399 Speaker 2: Yes, that figure is what first drove this whole narrative 100 00:04:54,399 --> 00:04:57,480 of superabundance. It suggested that maybe the most common type 101 00:04:57,480 --> 00:05:00,439 of planet in the galaxy isn't orbiting a starl ours, 102 00:05:00,439 --> 00:05:02,279 but is just wandering free. 103 00:05:02,360 --> 00:05:04,720 Speaker 1: And it's incredible that the technique is sensitive enough for 104 00:05:04,800 --> 00:05:07,839 not just these huge gas giants, but for smaller rocky 105 00:05:07,879 --> 00:05:08,879 worlds too well. 106 00:05:08,959 --> 00:05:12,199 Speaker 2: The technology keeps getting better, and that brings us to 107 00:05:12,240 --> 00:05:16,920 that amazing discovery in twenty twenty by the ogl E astronomers, 108 00:05:16,959 --> 00:05:21,560 again led by Prisimech Morose, they found the smallest rogue 109 00:05:21,639 --> 00:05:22,480 planet to date. 110 00:05:22,879 --> 00:05:24,040 Speaker 1: How small are we talking. 111 00:05:24,240 --> 00:05:27,079 Speaker 2: The microlensing event was so fast, the light curve was 112 00:05:27,120 --> 00:05:30,240 so brief, they figured the object was likely less massive 113 00:05:30,279 --> 00:05:32,920 than Earth, maybe closer to the mass of Mars. 114 00:05:33,160 --> 00:05:35,879 Speaker 1: A Mars mass object just floating out there in the void. 115 00:05:35,920 --> 00:05:38,319 I mean, there's no other way you would ever find that. 116 00:05:38,720 --> 00:05:42,000 Speaker 2: Ever, absolutely not. And what made that detection so solid 117 00:05:42,199 --> 00:05:44,800 was their follow up work. They could confidently rule out 118 00:05:44,800 --> 00:05:49,079 any star orbiting that little planet within about eight astronomical units. 119 00:05:48,800 --> 00:05:51,040 Speaker 1: So eight times the distance from the Earth to the Sun. 120 00:05:51,199 --> 00:05:53,240 That's a pretty big space to check. 121 00:05:53,079 --> 00:05:55,399 Speaker 2: A very big space. So it proves two things that 122 00:05:55,439 --> 00:05:58,399 these low mass free floaters exist and that our current 123 00:05:58,600 --> 00:06:01,959 ground based tech can actually find and characterize them if 124 00:06:01,959 --> 00:06:03,480 the alignment is absolutely perfect. 125 00:06:03,759 --> 00:06:05,480 Speaker 1: Okay, but this is where we have to pump the 126 00:06:05,480 --> 00:06:08,000 brakes a little, because the census isn't quite adding up, 127 00:06:08,040 --> 00:06:11,319 is it. We have some studies like Merritt Roy in 128 00:06:11,360 --> 00:06:15,040 twenty twenty one suggesting billions or even trillions of these things, 129 00:06:15,199 --> 00:06:18,279 which supports that super abundance idea, right, But then you 130 00:06:18,319 --> 00:06:22,000 have other more recent, very precise studies that seem to 131 00:06:22,040 --> 00:06:24,360 be pushing back suggesting the numbers are lower. 132 00:06:24,560 --> 00:06:28,079 Speaker 2: Exactly. This is a fierce debate in the scientific community. 133 00:06:28,120 --> 00:06:30,439 Right now, you have to contrast that high estimate with 134 00:06:31,120 --> 00:06:34,360 a twenty seventeen study, also from a Rose team. They 135 00:06:34,480 --> 00:06:37,680 used six times the statistical power of that original twenty 136 00:06:37,720 --> 00:06:38,759 eleven paper. 137 00:06:38,560 --> 00:06:39,399 Speaker 1: And what did they find. 138 00:06:39,920 --> 00:06:42,680 Speaker 2: They suggested an upper limit of only point two five 139 00:06:42,800 --> 00:06:45,639 jupiter mass free floaters per main sequence star. 140 00:06:46,000 --> 00:06:48,680 Speaker 1: Wait, so we went from two jupiter's per star down 141 00:06:48,720 --> 00:06:50,839 to a quarter of a jupiter per star. That is 142 00:06:50,839 --> 00:06:52,879 a massive discrepancy. What's going on there? 143 00:06:53,040 --> 00:06:56,040 Speaker 2: The problem is really understanding the full spectrum of what 144 00:06:56,079 --> 00:07:00,920 we call planetary mass objects or pmos, and just as importantly, 145 00:07:01,120 --> 00:07:02,879 the limitations of our detection methods. 146 00:07:03,000 --> 00:07:05,639 Speaker 1: Okay, so let's clarify that spectrum. Where do you draw 147 00:07:05,639 --> 00:07:09,000 the lines between a star, a brown dwarf, and a planet. 148 00:07:09,160 --> 00:07:13,240 Speaker 2: It's all about how they generate energy. Stars fuse hydrogen. 149 00:07:14,160 --> 00:07:18,199 Brown dwarfs are sort of failed stars. They're massive enough 150 00:07:18,240 --> 00:07:21,800 between thirteen and eighty jupiter masses to fuse deterium but 151 00:07:21,959 --> 00:07:22,759 not hydrogen. 152 00:07:23,199 --> 00:07:27,160 Speaker 1: And below that thirteen jupiter mass threshold you're in planetary territory. 153 00:07:27,319 --> 00:07:30,560 Speaker 2: Correct. Everything under that is in the planetary mass range. 154 00:07:31,079 --> 00:07:34,240 Gas giants, rocky planets, all the way down to commets, 155 00:07:34,600 --> 00:07:37,120 and that's the population of raid planets we're trying to count. 156 00:07:37,319 --> 00:07:40,560 Speaker 1: So our current detection methods must have a bias, a 157 00:07:40,720 --> 00:07:41,600 huge bias. 158 00:07:42,000 --> 00:07:45,519 Speaker 2: As some have pointed out, current microlensing surveys are inherently 159 00:07:45,560 --> 00:07:48,879 biased towards the higher end of that mass range, specifically 160 00:07:48,879 --> 00:07:50,759 the four to thirteen Jupiter mass objects. 161 00:07:50,800 --> 00:07:52,800 Speaker 1: Why is that Because. 162 00:07:52,560 --> 00:07:55,079 Speaker 2: A more massive object creates a more pronounced and a 163 00:07:55,120 --> 00:07:58,120 longer lasting lensing event. It's just easier to spot. So 164 00:07:58,160 --> 00:08:00,879 if your survey is optimized to find these heavier objects 165 00:08:01,000 --> 00:08:03,879 and it turns out those heavier objects are actually pretty rare, then. 166 00:08:03,800 --> 00:08:05,759 Speaker 1: Your overall population cout is going to come out looking 167 00:08:05,800 --> 00:08:06,800 really low exactly. 168 00:08:07,279 --> 00:08:10,120 Speaker 2: But if, as some of the ejection models suggest, the 169 00:08:10,199 --> 00:08:13,480 vast majority of these rogue planets are actually small rocky 170 00:08:14,000 --> 00:08:16,240 Mars or Earth mass objects. 171 00:08:15,920 --> 00:08:19,279 Speaker 1: Then we're just missing them. Their lensing events are too brief, 172 00:08:19,439 --> 00:08:23,560 too faint for our current ground based surveys to catch systematically. 173 00:08:23,920 --> 00:08:26,759 Speaker 2: That's the heart of the debate. The people who model 174 00:08:26,800 --> 00:08:29,759 the mass function all the way down to Pluto mass objects, 175 00:08:30,040 --> 00:08:33,440 they get these huge numbers, the trillions, because they assume 176 00:08:33,440 --> 00:08:37,080 it's a continuous distribution like grains of sand. The people 177 00:08:37,080 --> 00:08:39,879 who rely only on the current detection stats for the 178 00:08:39,879 --> 00:08:42,200 big guys, they get the smaller numbers. 179 00:08:42,360 --> 00:08:45,480 Speaker 1: The truth is probably somewhere in between, almost certainly. 180 00:08:45,840 --> 00:08:48,480 Speaker 2: But until we can actually detect those small ones reliably, 181 00:08:48,960 --> 00:08:50,080 we're kind of stuck guessing. 182 00:08:50,399 --> 00:08:53,799 Speaker 1: So we need a next generation tool, something specifically built 183 00:08:53,799 --> 00:08:56,919 to overcome this bias and just count them accurately. 184 00:08:57,320 --> 00:08:59,320 Speaker 2: And that is where the real excitement is right now. 185 00:09:00,039 --> 00:09:03,600 The solution is the Nancy Grace Roman Space Telescope RST. 186 00:09:04,240 --> 00:09:07,000 It's scheduled for launch by May twenty twenty seven, and 187 00:09:07,080 --> 00:09:08,519 it is an absolute game changer. 188 00:09:08,600 --> 00:09:11,039 Speaker 1: How does Roman get around the problems that the ground 189 00:09:11,039 --> 00:09:13,679 based telescopes have two huge advantages. 190 00:09:13,720 --> 00:09:16,759 Speaker 2: First, it's in space, no atmosphere to blur the images, 191 00:09:17,000 --> 00:09:19,879 so you get much sharper, more stable pictures, which is 192 00:09:19,919 --> 00:09:23,200 critical for measuring these tiny distortions. And the second it's instruments. 193 00:09:23,960 --> 00:09:27,279 They are designed to serve a massive, wide field of 194 00:09:27,399 --> 00:09:30,840 view with very high cadence. And it's going to be 195 00:09:30,879 --> 00:09:32,360 staring at the galactic bulge. 196 00:09:32,600 --> 00:09:35,759 Speaker 1: Why the bulge just because it's dense with stars. 197 00:09:35,519 --> 00:09:38,320 Speaker 2: That's exactly it. The bulge is the densest part of 198 00:09:38,360 --> 00:09:40,240 the Milky Way. It gives you millions and millions of 199 00:09:40,240 --> 00:09:44,639 potential background source stars. You need that huge population to 200 00:09:44,679 --> 00:09:47,240 maximize your chances of a rogue planet just happening to 201 00:09:47,279 --> 00:09:48,200 pass in front of one. 202 00:09:48,320 --> 00:09:50,480 Speaker 1: So what's the payoff? What kind of precision are we 203 00:09:50,559 --> 00:09:51,120 hoping for? 204 00:09:51,759 --> 00:09:54,960 Speaker 2: Roman is expected to give us a rogue planet count 205 00:09:55,360 --> 00:09:58,120 that is at least ten times more precise than what 206 00:09:58,159 --> 00:10:01,200 we have now. Wow, this will let us finally pin 207 00:10:01,320 --> 00:10:03,279 down the mass function. We won't have to guess if 208 00:10:03,279 --> 00:10:05,840 the galaxy is dominated by Jupiter sized rogues or Earth 209 00:10:05,919 --> 00:10:09,159 sized rogues. We'll have hard data. It will for the 210 00:10:09,200 --> 00:10:11,080 first time tell us if we live in a galaxy 211 00:10:11,120 --> 00:10:14,879 with tens of billions of these things or truly trillions. 212 00:10:15,039 --> 00:10:19,360 Speaker 1: So once Roman launches, will finally have a real answer. Okay, 213 00:10:19,360 --> 00:10:21,000 so if we know they're out there, the next obvious 214 00:10:21,080 --> 00:10:24,039 question is where did they come from. They're free floating, 215 00:10:24,080 --> 00:10:26,159 so they either had to be borne that way or 216 00:10:26,159 --> 00:10:28,279 they were violently exiled from home. 217 00:10:28,440 --> 00:10:32,039 Speaker 2: And that violence is really the key. The main theory, 218 00:10:32,039 --> 00:10:36,080 the most accepted one, is the ejected planet model. Most 219 00:10:36,080 --> 00:10:39,440 of these free floaters probably formed in a totally normal way, 220 00:10:39,840 --> 00:10:43,919 in a protoplanetary disc around a star, just like Earth. 221 00:10:43,840 --> 00:10:46,120 Speaker 1: But then something went horribly wrong. 222 00:10:45,960 --> 00:10:48,919 Speaker 2: Something went very wrong. The early years of a solar 223 00:10:48,919 --> 00:10:52,440 system are incredibly chaotic and turbulent. They were thrown out 224 00:10:52,480 --> 00:10:53,919 by gravitational interactions. 225 00:10:53,960 --> 00:10:55,919 Speaker 1: It's hard to really picture that. You know, our system 226 00:10:55,960 --> 00:10:59,480 seems so neat and orderly now, but you're saying it 227 00:10:59,559 --> 00:11:01,320 started out is a complete mess. 228 00:11:01,120 --> 00:11:05,440 Speaker 2: The total mess. The models show dozens, maybe hundreds, of 229 00:11:05,519 --> 00:11:09,559 planetary embryos in clumps of gas, all circling the young star. 230 00:11:10,080 --> 00:11:13,559 It's a gravitational binball game. You get eccentric orbits, collisions, 231 00:11:13,600 --> 00:11:16,080 and inevitably ejections, and it. 232 00:11:16,039 --> 00:11:18,080 Speaker 1: Seems like the smaller planets are the ones that are 233 00:11:18,080 --> 00:11:20,720 most likely to get the boot. The simulations suggest for 234 00:11:20,799 --> 00:11:23,120 stars like our Sun, the median mass of an injected 235 00:11:23,159 --> 00:11:24,639 planet is around point eight. 236 00:11:24,480 --> 00:11:27,639 Speaker 2: Earth masses, which is a really significant number because that 237 00:11:27,679 --> 00:11:30,000 lines up perfectly with why they're so hard to detect. 238 00:11:30,360 --> 00:11:32,960 The smaller the planet, the less tightly it's bound to 239 00:11:32,960 --> 00:11:34,039 its stars gravity. 240 00:11:33,759 --> 00:11:35,840 Speaker 1: So it's easier to kick out, much easier. 241 00:11:36,639 --> 00:11:38,759 Speaker 2: All it takes is a close encounter with a Jupiter 242 00:11:39,039 --> 00:11:42,840 or a Saturn, and that little rocky world achieves escape 243 00:11:42,919 --> 00:11:47,320 velocity and gets flung out into interstellar space. The process 244 00:11:47,360 --> 00:11:51,200 itself favors making small, rocky rogue planet, but. 245 00:11:51,159 --> 00:11:53,879 Speaker 1: That can't be the whole story. That model doesn't really 246 00:11:53,919 --> 00:11:56,960 explain the supermassive ones, does it, The ones that are 247 00:11:57,000 --> 00:11:59,919 you know, ten twelve times of the mass of Jupiter right. 248 00:12:00,720 --> 00:12:03,919 Speaker 2: For those, you need a different origin story. And that's 249 00:12:03,919 --> 00:12:07,000 this fascinating theory of direct collapse that some of these 250 00:12:07,000 --> 00:12:09,639 big planetary mass objects formed all by themselves. 251 00:12:09,639 --> 00:12:10,600 Speaker 1: How does that even work? 252 00:12:10,840 --> 00:12:13,440 Speaker 2: They form directly from the collapse of a cold, dense 253 00:12:13,519 --> 00:12:15,919 molecular cloud. It's the same way as star or a 254 00:12:15,919 --> 00:12:18,759 brown dwarf forms, but they just fail. They bypass the 255 00:12:18,759 --> 00:12:20,639 whole protoplanetary disks. 256 00:12:20,440 --> 00:12:23,360 Speaker 1: Stage entirely, so they just condense out of the primordial 257 00:12:23,399 --> 00:12:25,600 gas and dust, but they don't quite gather enough mass 258 00:12:25,600 --> 00:12:28,120 to ignite fusion. They're basically failed stars. 259 00:12:28,399 --> 00:12:30,279 Speaker 2: That's one way to think of it. It's often called 260 00:12:30,279 --> 00:12:34,279 the halted decretion scenario. You have a stellar embryo forming 261 00:12:34,360 --> 00:12:37,399 in a crowded star nursery, but before it can pack 262 00:12:37,440 --> 00:12:40,399 on enough weight to start burning deuterium, it has a close, 263 00:12:40,759 --> 00:12:44,759 violent encounter with a bigger newborn star nearby and gets ejected. 264 00:12:44,840 --> 00:12:46,600 Speaker 1: So it gets kicked out of the nursery before it 265 00:12:46,600 --> 00:12:47,519 can grow up into. 266 00:12:47,360 --> 00:12:50,639 Speaker 2: A star, and it's doomed to wander the galaxy forever 267 00:12:51,080 --> 00:12:54,559 as a planetary mass object. That's how you can get 268 00:12:54,600 --> 00:12:57,799 a twelve jupiter mass object that has never ever had 269 00:12:57,840 --> 00:12:58,519 a parent star. 270 00:12:59,039 --> 00:13:01,240 Speaker 1: To really get them, machare anx of that ejection. We 271 00:13:01,360 --> 00:13:03,919 have to talk about the engine behind all this chaos, 272 00:13:03,960 --> 00:13:08,080 which is orbital resonance. It's how a tiny, repeated push 273 00:13:08,240 --> 00:13:10,759 can just completely destroy a stable orbit. 274 00:13:11,080 --> 00:13:14,320 Speaker 2: Resonance is such a powerful concept in physics. It's when 275 00:13:14,360 --> 00:13:18,120 some external push lines up perfectly with an object's natural rhythm. 276 00:13:18,360 --> 00:13:21,639 That matching just amplifies the effect way beyond what you'd expect. 277 00:13:21,759 --> 00:13:24,240 Speaker 1: I love the guitar analogy that Paul Sutter uses. You 278 00:13:24,240 --> 00:13:26,360 pluck a string and that tiny bit of energy gets 279 00:13:26,399 --> 00:13:28,960 magnified because the whole wooden body of the guitar is 280 00:13:28,960 --> 00:13:32,200 designed to resonate at those frequencies. A small force creates 281 00:13:32,200 --> 00:13:32,960 a huge. 282 00:13:32,679 --> 00:13:36,919 Speaker 2: Sound, and a planet's orbit is its natural rhythm. If 283 00:13:36,960 --> 00:13:39,559 another big planet's gravity gives it a little nudge in 284 00:13:39,720 --> 00:13:42,639 sync over and over again, then nudge adds up. 285 00:13:42,600 --> 00:13:46,159 Speaker 1: So let's use that dramatic scenarios. Sutter describes a hypothetical 286 00:13:46,720 --> 00:13:49,879 two to one resonance between Earth and Jupiter. Earth goes 287 00:13:49,919 --> 00:13:52,399 around twice for every one Jupiter orbit. 288 00:13:52,639 --> 00:13:56,120 Speaker 2: In that situation, every two years, Earth and Jupiter line 289 00:13:56,159 --> 00:13:58,600 up in the same part of space, and every two 290 00:13:58,679 --> 00:14:03,159 years Jupiter gives Earth a tiny, tiny gravitational boost. But 291 00:14:03,399 --> 00:14:06,159 because it happens regularly, like clockwork. 292 00:14:05,759 --> 00:14:08,360 Speaker 1: It reinforces itself. The effect compounds over. 293 00:14:08,240 --> 00:14:11,960 Speaker 2: Time, Yes, over hundreds of thousands of years. That tiny 294 00:14:12,000 --> 00:14:15,120 cumulative boost adds a little bit more energy to Earth's orbit, 295 00:14:15,600 --> 00:14:18,559 a tiny gain in speed with every pass, and eventually, 296 00:14:18,679 --> 00:14:21,399 eventually those tiny gains would push Earth to a velocity 297 00:14:21,440 --> 00:14:24,360 greater than the Sun's escape velocity, which is about forty 298 00:14:24,360 --> 00:14:27,240 two kilometers per second from our position. Once you cross 299 00:14:27,279 --> 00:14:30,159 that line, you're gone ejected from the Solar System for good. 300 00:14:30,480 --> 00:14:33,720 Speaker 1: It's just astonishing to think that our entire system stability 301 00:14:33,759 --> 00:14:35,759 hangs on the fact that our big planets aren't in 302 00:14:35,840 --> 00:14:38,080 these clean, simple resonances right now. 303 00:14:38,279 --> 00:14:41,120 Speaker 2: The difference between a stable home and a mass ejection 304 00:14:41,240 --> 00:14:43,879 event can be just a tiny fraction of a percent. 305 00:14:44,200 --> 00:14:47,399 In an orbital period, the early Solar System was cleared 306 00:14:47,399 --> 00:14:49,840 out by this exact mechanism. 307 00:14:49,399 --> 00:14:53,039 Speaker 1: And that process stocked the galaxy with all these wanderers, 308 00:14:53,679 --> 00:14:57,440 which brings us to cosmic interlopers, the idea that interstellar 309 00:14:57,480 --> 00:15:00,200 space is just full of graffic and that's some of 310 00:15:00,279 --> 00:15:03,519 it is constantly passing through our own Solar system, and. 311 00:15:03,440 --> 00:15:06,360 Speaker 2: This was all just theory until quite recently. The idea 312 00:15:06,399 --> 00:15:09,879 that our Solar system was this isolated island was completely 313 00:15:09,919 --> 00:15:14,320 shattered in twenty seventeen with a discovery of Umuomo. 314 00:15:13,600 --> 00:15:16,279 Speaker 1: The first confirmed interstellar object. 315 00:15:15,919 --> 00:15:18,759 Speaker 2: The first one, and its trajectory was the smoking Gun. 316 00:15:19,120 --> 00:15:21,200 It followed a hyperbolic orbit. 317 00:15:21,000 --> 00:15:22,600 Speaker 1: Which means it came in with too much speed to 318 00:15:22,600 --> 00:15:24,840 get captured right. It swung around the Sun and was 319 00:15:24,879 --> 00:15:26,360 on its way out, never to return. 320 00:15:26,399 --> 00:15:29,200 Speaker 2: Precisely, it was not gravitationally bound to our Sun at all, 321 00:15:29,320 --> 00:15:32,360 and that confirmed that, yes, objects from other star systems 322 00:15:32,399 --> 00:15:35,000 are regular visitors. And we've seen a whole variety since then. 323 00:15:35,279 --> 00:15:36,600 Asteroids comments. 324 00:15:36,799 --> 00:15:39,639 Speaker 1: Let's talk about that weird interstellar comet three I eight 325 00:15:39,720 --> 00:15:42,399 lists the one that passed near Mars orbit in twenty 326 00:15:42,440 --> 00:15:45,480 twenty five. It had some really strange behavior. 327 00:15:45,840 --> 00:15:50,000 Speaker 2: Three I at lists was a fascinating look at alien chemistry. Normally, 328 00:15:50,039 --> 00:15:52,559 a comet gets near the Sun and the solar wind 329 00:15:52,639 --> 00:15:55,440 pushes the dust and gas away from the Sun, forming 330 00:15:55,440 --> 00:15:55,840 a tail. 331 00:15:56,000 --> 00:15:58,559 Speaker 1: But this one had a tail that was pointing towards. 332 00:15:58,200 --> 00:16:00,919 Speaker 2: The Sun, a sun facing tail, which just seemed to 333 00:16:00,960 --> 00:16:02,000 defy physics. 334 00:16:02,120 --> 00:16:03,200 Speaker 1: So what was the explanation. 335 00:16:03,720 --> 00:16:06,279 Speaker 2: The thinking is that the dust particles coming off of 336 00:16:06,320 --> 00:16:10,120 it were just really big and heavy, hundreds of microns across, 337 00:16:10,399 --> 00:16:13,399 think more like coarse sand than fine powder. They were 338 00:16:13,440 --> 00:16:16,360 just too heavy for the Sun's radiation pressure to effectively 339 00:16:16,399 --> 00:16:17,120 blow them away. 340 00:16:17,320 --> 00:16:20,080 Speaker 1: So the momentum of the particles coming off the comet 341 00:16:20,360 --> 00:16:22,960 was stronger than the push from the sunlight exactly. 342 00:16:23,159 --> 00:16:25,840 Speaker 2: And what that tells us is that the protoplanetary disk 343 00:16:25,879 --> 00:16:28,600 where three Ilists was born must have been very different 344 00:16:28,639 --> 00:16:31,360 from ours. It must have been rich in whatever material 345 00:16:31,840 --> 00:16:35,360 allows these big, heavy dust grains to form. It's a 346 00:16:35,360 --> 00:16:38,799 tiny chemical window into another star system light years away. 347 00:16:38,600 --> 00:16:40,440 Speaker 1: And we're not just watching these things fly by. Earth 348 00:16:40,480 --> 00:16:43,440 itself is kind of a passive collector for the smaller bits. 349 00:16:43,759 --> 00:16:47,039 The twenty fourteen Manis Island meteor is a perfect case study. 350 00:16:47,320 --> 00:16:50,000 Speaker 2: That was the incredible work from the Saraje and Load paper. 351 00:16:50,720 --> 00:16:53,559 They figured out that meteor had to be intertellar because 352 00:16:53,559 --> 00:16:57,080 of its insane velocity. It was traveling at over forty 353 00:16:57,080 --> 00:16:59,960 three kilometers per second before it even entered our Solar system. 354 00:17:00,159 --> 00:17:04,279 Speaker 1: That speed, that trajectory, there's no other explanation. It had 355 00:17:04,279 --> 00:17:05,480 to come from outside. 356 00:17:05,559 --> 00:17:08,680 Speaker 2: It did, and it just highlights this idea that Earth's 357 00:17:08,759 --> 00:17:12,759 atmosphere is like a giant fishing net. We are constantly 358 00:17:12,839 --> 00:17:16,720 sampling tiny bits of interstellar debris. We might literally have 359 00:17:16,839 --> 00:17:19,039 fragments of an exoplanet sitting at the bottom of the 360 00:17:19,119 --> 00:17:20,480 Pacific Ocean right now. 361 00:17:20,359 --> 00:17:24,240 Speaker 1: Which is an amazing scientific opportunity, but it also raises 362 00:17:24,279 --> 00:17:27,680 the stakes for potential hazards. We have to talk about 363 00:17:27,680 --> 00:17:31,640 the rare but pretty chilling scenario of a major disruption. 364 00:17:31,839 --> 00:17:35,640 Speaker 2: The danger from a wandering star over geologic time is real. 365 00:17:36,079 --> 00:17:38,359 A close pass from a star wandering in from the 366 00:17:38,359 --> 00:17:41,599 depths of the galaxy could seriously disrupt the delicate balance 367 00:17:41,640 --> 00:17:42,160 of our system. 368 00:17:42,240 --> 00:17:45,319 Speaker 1: And the worst case scenario, however unlikely, is a gravitational 369 00:17:45,359 --> 00:17:47,599 tug strong enough to just fling Earth out of the 370 00:17:47,599 --> 00:17:48,720 Solar System entirely. 371 00:17:48,799 --> 00:17:52,000 Speaker 2: It's not impossible, but even a much more distant pass 372 00:17:52,039 --> 00:17:54,920 can cause problems. It stirs up the Oort cloud. 373 00:17:54,839 --> 00:17:58,759 Speaker 1: Which is our Solar System's huge, vast outermost shell of 374 00:17:58,960 --> 00:17:59,720 icy bodies. 375 00:17:59,519 --> 00:18:02,480 Speaker 2: Right of them, and these passing stars act like a 376 00:18:02,519 --> 00:18:06,519 giant gravitational spoons. During that pod, they tweak the orbits 377 00:18:06,519 --> 00:18:08,720 of all those icy bodies, and some of them get 378 00:18:08,720 --> 00:18:10,599 sent tumbling towards the inner Solar System. 379 00:18:10,640 --> 00:18:12,640 Speaker 1: And there's a huge timelag on that isn't. 380 00:18:12,400 --> 00:18:15,799 Speaker 2: There a massive one. A star could pass by today, 381 00:18:16,079 --> 00:18:18,440 but it might take two million years for the wave 382 00:18:18,519 --> 00:18:21,599 of comets it disturbed to actually reach us. So a 383 00:18:21,640 --> 00:18:25,000 stellar passage that happened when our early ancestors were walking 384 00:18:25,039 --> 00:18:28,119 the Earth could be causing a small increase in impacts today. 385 00:18:28,640 --> 00:18:31,720 Speaker 1: But it's not all destructive. The Sun can also be 386 00:18:31,759 --> 00:18:34,839 a collector. This idea from the Belbruno study that our 387 00:18:34,880 --> 00:18:38,240 Sun can actually capture rogue planets that seems to defy 388 00:18:38,359 --> 00:18:39,519 celestial mechanics. 389 00:18:40,000 --> 00:18:42,759 Speaker 2: It's incredibly hard to do. To get captured, an object 390 00:18:42,839 --> 00:18:45,319 needs to lose a lot of speed. Normally, that would 391 00:18:45,319 --> 00:18:48,400 require a perfect slingshot maneuver around a planet like Jupiter 392 00:18:48,480 --> 00:18:49,599 on its very first. 393 00:18:49,400 --> 00:18:52,079 Speaker 1: Pass, which seems wildly improbable. 394 00:18:52,319 --> 00:18:56,559 Speaker 2: It is, but Belbruno's models suggest it's possible over millions 395 00:18:56,559 --> 00:18:58,880 of years, even without that perfect slingshot. 396 00:18:58,960 --> 00:18:59,680 Speaker 1: How does that work? 397 00:19:00,079 --> 00:19:04,680 Speaker 2: Factored in the galactic tide, the subtle but constant gravitational 398 00:19:04,720 --> 00:19:07,279 pull of the entire Milky Way on our Solar System 399 00:19:07,880 --> 00:19:11,119 over millions of years, that tide acts like a tiny 400 00:19:11,240 --> 00:19:14,000 gentle break on an incoming robe planet. 401 00:19:14,200 --> 00:19:17,640 Speaker 1: The galaxy itself slows it down just enough, just. 402 00:19:17,640 --> 00:19:21,240 Speaker 2: Enough for the Sun's gravity to grappled. These captures aren't quick. 403 00:19:21,640 --> 00:19:24,160 The planet would go into a long, unstable orbit and 404 00:19:24,160 --> 00:19:27,519 then slowly spiral in over millions of years until it's 405 00:19:27,559 --> 00:19:28,480 permanently trapped. 406 00:19:28,680 --> 00:19:31,079 Speaker 1: So we could have captured rogue planets in our Solar 407 00:19:31,079 --> 00:19:33,400 System right now, hiding out in the far reaches. 408 00:19:33,599 --> 00:19:35,880 Speaker 2: We could, and we might even be able to find 409 00:19:35,880 --> 00:19:38,319 them by looking for their tiny gravitational tugs in the 410 00:19:38,440 --> 00:19:41,119 orbits of Neptune or Uranus. We might find proof that 411 00:19:41,160 --> 00:19:43,640 our Sun is actively hoarding worlds from other star systems. 412 00:19:43,720 --> 00:19:46,640 Speaker 1: Okay, let's pivot from mechanics to astrobiology, because this is 413 00:19:46,640 --> 00:19:49,119 where it gets really wild. The idea that life could 414 00:19:49,119 --> 00:19:52,759 exist on a world with no Sun It just completely 415 00:19:52,839 --> 00:19:54,960 upends our definition of a habitable zone. 416 00:19:55,200 --> 00:19:57,839 Speaker 2: It forces you to rethink the entire energy chain of 417 00:19:57,880 --> 00:20:01,720 an ecosystem. Here on Earth, almost everything traces back to 418 00:20:01,759 --> 00:20:05,359 the Sun. On a rogue planet, the entire system has 419 00:20:05,400 --> 00:20:08,880 to be one hundred percent powered from the inside, no 420 00:20:09,039 --> 00:20:10,400 photons involved at all. 421 00:20:10,799 --> 00:20:13,559 Speaker 1: So what's the power source? What keeps these worlds warm 422 00:20:13,640 --> 00:20:15,440 enough for liquid water if there's no star? 423 00:20:16,079 --> 00:20:19,519 Speaker 2: Two main things. First, you have primordial heat, just the 424 00:20:19,599 --> 00:20:22,319 leftover heat from when the planet first formed. But more 425 00:20:22,359 --> 00:20:25,440 importantly for the long haul, you have radiogenic. 426 00:20:24,839 --> 00:20:28,039 Speaker 1: Heat from the decay of radioactive elements in the core. 427 00:20:27,960 --> 00:20:32,160 Speaker 2: Exactly things like uranium, thorium, potassium. Their decay generates a 428 00:20:32,160 --> 00:20:34,039 steady stream of heat from the inside out. 429 00:20:34,160 --> 00:20:35,319 Speaker 1: And how long can that last? 430 00:20:35,640 --> 00:20:39,279 Speaker 2: For billions of years, a rocky Earth sized planet could 431 00:20:39,319 --> 00:20:42,200 have a warm core and mantle for GigE years, which 432 00:20:42,240 --> 00:20:44,799 is plenty of time for simple life to potentially evolve. 433 00:20:45,000 --> 00:20:47,000 Speaker 1: And as a third option, right if the planet got 434 00:20:47,000 --> 00:20:48,160 ejected with a moon. 435 00:20:48,079 --> 00:20:51,759 Speaker 2: Yes, tidal forces. If a rogue planet has a moon 436 00:20:51,799 --> 00:20:55,519 in a slightly eccentric orbit, the constant gravitational stretching and 437 00:20:55,519 --> 00:20:58,359 squeezing of the moon generates a tremendous amount of internal 438 00:20:58,359 --> 00:21:00,400 friction and heat the Io effect. 439 00:21:00,880 --> 00:21:04,480 Speaker 1: Jupiter's gravity makes its moon io the most volcanically active 440 00:21:04,519 --> 00:21:05,799 body in our Solar System. 441 00:21:05,839 --> 00:21:09,240 Speaker 2: The exact same principle, a rogue planet Moon system could 442 00:21:09,279 --> 00:21:13,079 create a geologically active environment with subsurface water even in 443 00:21:13,079 --> 00:21:15,279 the absolute cold of deep space. 444 00:21:15,160 --> 00:21:19,039 Speaker 1: All of which supports this water world's hypothesis, the idea 445 00:21:19,079 --> 00:21:22,680 of a vast dark subsurface biosphere. 446 00:21:22,720 --> 00:21:25,839 Speaker 2: The hypothesis is that these Earth sized rogue planets can 447 00:21:25,920 --> 00:21:29,680 maintain liquid oceans for billions of years, but they're hidden 448 00:21:29,920 --> 00:21:32,599 beneath a thick crust of ice. The ice acts as 449 00:21:32,640 --> 00:21:34,160 a perfect insulator. 450 00:21:33,880 --> 00:21:36,799 Speaker 1: So the surface is hundreds of degrees below zero, frozen 451 00:21:36,839 --> 00:21:39,960 solid from miles, but deep underneath you have a warm, 452 00:21:40,039 --> 00:21:43,680 liquid pressurized ocean, a perfect habitat for extremophiles. 453 00:21:43,720 --> 00:21:45,960 Speaker 2: It could be. And what's really interesting is how an 454 00:21:46,000 --> 00:21:49,160 atmosphere could help. If a rogue planet held onto a thick, 455 00:21:49,200 --> 00:21:52,720 heavy atmosphere, maybe helium from its berth cloud, that atmosphere 456 00:21:52,759 --> 00:21:54,160 would act like a blanket. 457 00:21:53,880 --> 00:21:55,839 Speaker 1: Trapping the internal heat that's trying to escape. 458 00:21:55,960 --> 00:21:58,680 Speaker 2: Right. It would act as a powerful dark greenhouse gas 459 00:21:59,000 --> 00:22:01,960 keeping that subsurface ocean liquid for even longer. It just 460 00:22:02,039 --> 00:22:04,960 completely expands the possibilities for where life could exist. 461 00:22:05,119 --> 00:22:09,200 Speaker 1: And the ultimate biological implication here is pans bumia, the 462 00:22:09,279 --> 00:22:13,720 idea of rogue planets as cosmic seed pods spreading life 463 00:22:13,720 --> 00:22:14,720 across the galaxy. 464 00:22:14,799 --> 00:22:17,839 Speaker 2: It's a powerful idea. If these worlds can sustain life 465 00:22:17,839 --> 00:22:21,440 for billions of years, they become transport vehicles. Imagine a 466 00:22:21,519 --> 00:22:25,640 rogue planet carrying dormant microbes in its icy shell, passes 467 00:22:25,759 --> 00:22:29,599 very close to a nice, warm, habitable planet in another system. 468 00:22:29,720 --> 00:22:32,559 Speaker 1: The gravity of that system could rip the rogue planet apart. 469 00:22:32,759 --> 00:22:36,000 Speaker 2: Exactly, it could tear off the outer layers, scattering debris, 470 00:22:36,000 --> 00:22:39,000 ice and rock seeded with life into the new system. 471 00:22:39,200 --> 00:22:42,039 Some of that debris could then land on the habitable. 472 00:22:41,519 --> 00:22:44,480 Speaker 1: World, seeding it with life from another part of the galaxy. 473 00:22:44,640 --> 00:22:46,960 Speaker 2: It suggests that life on different worlds might not be 474 00:22:47,119 --> 00:22:49,960 entirely unique. We might all share sort of much traveled 475 00:22:50,039 --> 00:22:51,839 chemical history. It's an incredible thought. 476 00:22:52,119 --> 00:22:54,920 Speaker 1: The idea of them as transport vehicles naturally leads to 477 00:22:54,960 --> 00:22:59,160 this final section interstellar travel. Could these rogue planets be 478 00:22:59,200 --> 00:23:02,359 a pathway for US, US or some other civilization to 479 00:23:02,440 --> 00:23:03,680 migrate between the stars. 480 00:23:03,920 --> 00:23:06,359 Speaker 2: This is that fundamental shift in perspective. They stop being 481 00:23:06,359 --> 00:23:09,160 hazards and they become infrastructure. They're stepping stones. 482 00:23:08,960 --> 00:23:12,240 Speaker 1: Which brings us to this concept of island hopping, like 483 00:23:12,279 --> 00:23:15,799 how Polynesian cultures spread across the Pacific, not in one 484 00:23:15,839 --> 00:23:18,240 giant leap, but from island to island. 485 00:23:18,559 --> 00:23:21,440 Speaker 2: The thinking is that interstellar migration might not be some 486 00:23:21,680 --> 00:23:25,240 huge government funded project to build a giant starship. It 487 00:23:25,319 --> 00:23:29,119 might be a much slower, more organic economic expansion that 488 00:23:29,240 --> 00:23:32,839 takes millennia, and it starts in our own ort cloud. 489 00:23:32,960 --> 00:23:36,440 Speaker 1: So for a future civilization living in space, the trillions 490 00:23:36,480 --> 00:23:40,759 of icy objects in the ork cloud are just resources. 491 00:23:40,319 --> 00:23:44,559 Speaker 2: Raw materials ice for water and fuel, rock for building materials. 492 00:23:44,759 --> 00:23:47,839 You could haul them out build habitats inside. A civilization 493 00:23:47,960 --> 00:23:51,200 starts by colonizing the inner org cloud. When that gets crowded, 494 00:23:51,240 --> 00:23:53,759 the next generation just moves out to the next object. 495 00:23:53,839 --> 00:23:57,039 Speaker 1: So it's a slow, steady expansion driven by population growth 496 00:23:57,039 --> 00:23:59,759 and resource needs, until eventually you get to the edge 497 00:23:59,759 --> 00:24:01,759 of our ork cloud where it starts to blur with 498 00:24:01,759 --> 00:24:04,440 the ork cloud of the next star over like Alpha centaury. 499 00:24:04,759 --> 00:24:08,039 Speaker 2: And that's the key insight. The energy cost to hop 500 00:24:08,079 --> 00:24:11,039 from an object barely bound to our Sun to one 501 00:24:11,079 --> 00:24:15,960 barely bound to Alpha Centauri is incredibly low. You've eliminated 502 00:24:15,960 --> 00:24:20,440 the giant political and technical barrier of a dedicated interstellar mission. 503 00:24:20,720 --> 00:24:21,759 It's just a settlement. 504 00:24:21,920 --> 00:24:25,400 Speaker 1: And this feeds right into that cosmic hitchhiker's idea, which. 505 00:24:25,200 --> 00:24:28,160 Speaker 2: Takes it a step further, and advanced civilization might not 506 00:24:28,240 --> 00:24:31,720 just hop between little icy bodies. They might actively seek 507 00:24:31,759 --> 00:24:35,480 out and colonize an entire free floating planet to use 508 00:24:35,480 --> 00:24:36,640 as a transport vehicle. 509 00:24:36,759 --> 00:24:39,200 Speaker 1: But why ride a planet instead of building a ship? 510 00:24:39,319 --> 00:24:41,400 What's the real advantage scale and time? 511 00:24:41,920 --> 00:24:45,880 Speaker 2: A rogue planet is already a massive radiation shielded habitat. 512 00:24:45,960 --> 00:24:49,799 It has its own internal geothermal energy, it has geological stability. 513 00:24:49,880 --> 00:24:52,240 You don't have to build a generation ship from scratch. 514 00:24:52,440 --> 00:24:54,279 You just move into a pre built one that's the 515 00:24:54,319 --> 00:24:54,880 size of Earth. 516 00:24:54,960 --> 00:24:56,799 Speaker 1: So you're hitching a ride on a world ship that's 517 00:24:56,799 --> 00:24:59,240 already migrating through the galaxy on its own natural course. 518 00:24:59,319 --> 00:25:02,039 Speaker 2: It bypasses so many of the engineering challenges. Plus you 519 00:25:02,079 --> 00:25:04,640 have a planet's worth of resources at your disposal. 520 00:25:04,799 --> 00:25:08,119 Speaker 1: But there is a massive energy problem here. Once you're 521 00:25:08,160 --> 00:25:11,519 out past the Kuiper Belt, solar power is useless. You 522 00:25:11,559 --> 00:25:13,640 need a massive, reliable power source. 523 00:25:14,039 --> 00:25:17,039 Speaker 2: This is the critical debate. The resources in the Ord 524 00:25:17,079 --> 00:25:22,000 cloud are a problem. These icy bodies are undifferentiated. They're 525 00:25:22,000 --> 00:25:23,720 just a mix of ice and dust. They are not 526 00:25:23,880 --> 00:25:28,039 like Earth, where geological processes have concentrated heavy elements like 527 00:25:28,160 --> 00:25:30,119 uranium into minable ores. 528 00:25:30,279 --> 00:25:32,240 Speaker 1: So you can't just go out there and mine for 529 00:25:32,400 --> 00:25:34,759 uranium to fuel fission reactors. 530 00:25:34,359 --> 00:25:38,160 Speaker 2: Not effectively. The calculation by joy On this is just stark. 531 00:25:38,240 --> 00:25:39,880 It really puts the problem into perspective. 532 00:25:39,960 --> 00:25:40,640 Speaker 1: Lay it out for us. 533 00:25:40,759 --> 00:25:43,279 Speaker 2: He calculated that if you took one ton of typical 534 00:25:43,279 --> 00:25:46,440 Oort cloud material, the amount of fission energy you could 535 00:25:46,480 --> 00:25:49,079 get from the uranium scattered within it would be enough 536 00:25:49,079 --> 00:25:51,279 to melt just ten kilograms of ice a. 537 00:25:51,240 --> 00:25:53,640 Speaker 1: Ton of rock to heat ten liters of water. 538 00:25:53,880 --> 00:25:57,119 Speaker 2: It's an unbelievably low energy yield. You cannot run an 539 00:25:57,119 --> 00:25:58,599 industrial civilization on that. 540 00:25:58,799 --> 00:26:01,440 Speaker 1: So what's the conclusion. Fission is a dead end for 541 00:26:01,480 --> 00:26:02,920 an outer system civilization. 542 00:26:03,200 --> 00:26:06,480 Speaker 2: It is the only way to support a thriving, expanding 543 00:26:06,480 --> 00:26:09,319 civilization out there. The only way to make this interstellar 544 00:26:09,359 --> 00:26:12,599 island hopping work is one technology. 545 00:26:12,839 --> 00:26:13,720 Speaker 1: It has to be fusion. 546 00:26:13,799 --> 00:26:16,799 Speaker 2: It has to be fusion, fusion, and more fusion. The 547 00:26:16,920 --> 00:26:20,880 raw materials deuterium from the ice are abundant, but you 548 00:26:20,960 --> 00:26:25,119 absolutely must have mastered contained fusion power. Without it, the 549 00:26:25,160 --> 00:26:28,839 outer Solar System is and always will be a resource desert. 550 00:26:29,079 --> 00:26:32,680 Speaker 1: So we've woven together these incredible threads, the trillions of 551 00:26:32,799 --> 00:26:35,599 unseen worlds, the tech we're building to finally see them, 552 00:26:36,000 --> 00:26:39,839 the sheer violence of their creation, and this profound potential 553 00:26:39,880 --> 00:26:42,759 for them to harbor life or even become our own 554 00:26:42,920 --> 00:26:44,279 dark road to the stars. 555 00:26:44,480 --> 00:26:46,599 Speaker 2: And it's just so important to remember that these objects, 556 00:26:46,680 --> 00:26:49,279 the Wanderers, they used to be pure science fiction. Now 557 00:26:49,319 --> 00:26:52,240 they're hard science. They might be the single largest population 558 00:26:52,279 --> 00:26:54,680 of planetary mass objects in the whole galaxy. 559 00:26:54,920 --> 00:26:56,759 Speaker 1: And the image that sticks with me is the one 560 00:26:56,799 --> 00:26:59,839 we started with that right now tonight, there are worlds 561 00:27:00,200 --> 00:27:03,680 than Pluto born in star systems light years away, with 562 00:27:03,799 --> 00:27:07,319 our own unique chemistry, passing silently through the outer edges 563 00:27:07,359 --> 00:27:09,400 of our own Solar system, and we would never even 564 00:27:09,440 --> 00:27:11,519 know they were there. The universe is just so much 565 00:27:11,559 --> 00:27:15,000 more crowded, so much more chaotic than our eyes can see. 566 00:27:15,119 --> 00:27:18,319 Our Solar System isn't an island, it's an active participant 567 00:27:18,400 --> 00:27:19,640 in the traffic of the galaxy. 568 00:27:20,279 --> 00:27:21,759 Speaker 2: So we want to leave you with a question to 569 00:27:21,799 --> 00:27:25,359 think about. If you had the choice to live on 570 00:27:25,400 --> 00:27:27,759 a planet like ours, bound to the warmth and light 571 00:27:27,799 --> 00:27:30,440 of the Sun, or to take up residence on a slow, 572 00:27:30,880 --> 00:27:35,880 self contained worldship perpetually migrating through the galaxy's darkness, sustained 573 00:27:35,880 --> 00:27:38,759 only by its own internal power, which would you choose? 574 00:27:38,839 --> 00:27:40,240 And why let us know what you think.