WEBVTT 1 00:00:03.439 --> 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 Astronomie 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 --> 00:00:23.839 slumber under the night sky. 7 00:00:26.879 --> 00:00:29.280 So I want you to just imagine something for a second. Okay, 8 00:00:29.559 --> 00:00:33.200 picture a ghost, but you know, not a sheet wearing 9 00:00:33.240 --> 00:00:34.520 hovering in a hallway. 10 00:00:34.200 --> 00:00:36.960 Kind of ghost, right, something a bit more substantial exactly. 11 00:00:36.960 --> 00:00:40.479 I'm talking about a cosmic ghost, an entity that possesses 12 00:00:40.520 --> 00:00:44.000 the mass of one million of our suns. That is 13 00:00:44.159 --> 00:00:46.799 a lot of mass, it really is. And it's just 14 00:00:46.960 --> 00:00:51.439 wandering entirely invisible through the dark, quiet suburbs of a 15 00:00:51.479 --> 00:00:52.399 distant galaxy. 16 00:00:52.560 --> 00:00:54.719 Just completely out in the open, but totally hidden. 17 00:00:55.119 --> 00:00:57.679 Yeah, because it emits absolutely zero light. I mean, it 18 00:00:57.719 --> 00:01:00.719 makes no sound. It is a perfect voice drifting through 19 00:01:00.759 --> 00:01:01.840 the blackness of space. 20 00:01:02.079 --> 00:01:04.680 It is the ultimate cosmic ambush, really. 21 00:01:04.519 --> 00:01:07.879 Right, And the only reason we even know this staggering 22 00:01:07.920 --> 00:01:09.879 thing is out there, the only reason we can perceive 23 00:01:09.920 --> 00:01:13.200 it at all is because it just violently ate a star, a. 24 00:01:13.200 --> 00:01:17.319 Million solar masses of pure gravity, completely hidden until the 25 00:01:17.439 --> 00:01:20.159 exact moment a star takes one wrong step. 26 00:01:20.359 --> 00:01:23.159 And today is July twenty seven, twenty twenty six, and 27 00:01:23.200 --> 00:01:26.120 the entire world of astronomy just realized they were looking 28 00:01:26.159 --> 00:01:28.879 at a massive reality bending paradigm shift. 29 00:01:28.680 --> 00:01:31.120 Because it completely breaks the rules we thought we knew. 30 00:01:31.400 --> 00:01:34.640 It totally does because we are looking at the discovery 31 00:01:35.159 --> 00:01:39.120 of one of the universe's absolute rarest events. I'm talking 32 00:01:39.159 --> 00:01:43.040 about a supermassive black hole, a true monster that is 33 00:01:43.040 --> 00:01:44.159 not where it is supposed to be. 34 00:01:44.400 --> 00:01:47.239 It's tens of thousands of light years away from its 35 00:01:47.359 --> 00:01:48.319 designated home. 36 00:01:48.680 --> 00:01:52.040 Right. It is a rogue, a wanderer. But you know, 37 00:01:52.159 --> 00:01:54.040 before we get to the fact that this black hole 38 00:01:54.120 --> 00:01:57.120 is wandering through the galactic suburbs, we really need to 39 00:01:57.159 --> 00:01:57.840 set the scene. 40 00:01:57.959 --> 00:02:00.319 Yeah, we have to talk about the catalyst. 41 00:02:00.040 --> 00:02:05.640 Exactly, the murder scene itself. What exactly happens physically when 42 00:02:05.680 --> 00:02:08.280 a star wanders too close to an invisible monster. 43 00:02:08.520 --> 00:02:11.439 Well, the actual scientific term for this catalyst is a 44 00:02:11.479 --> 00:02:14.879 tidal disruption event, or we usually just call it a TDE. 45 00:02:15.080 --> 00:02:16.759 A TDE, got it, And it is. 46 00:02:16.759 --> 00:02:19.960 Truly one of the most violent physical processes in the 47 00:02:20.000 --> 00:02:22.919 known universe. To understand what happens, you really have to 48 00:02:22.960 --> 00:02:26.199 look at the mechanics of gravity. Okay, specifically, you have 49 00:02:26.240 --> 00:02:28.919 to understand that the gravity of a supermassive black hole 50 00:02:29.039 --> 00:02:32.159 isn't just strong, it creates this extreme gradient. 51 00:02:32.319 --> 00:02:35.719 The gradient meaning the poll is significantly stronger the closer 52 00:02:35.759 --> 00:02:38.680 you get ragsactly, But wait, gravity always gets stronger the 53 00:02:38.719 --> 00:02:41.680 closer you get to something like That's just how gravity works. 54 00:02:41.960 --> 00:02:45.599 Why is it so extreme here that it literally shreds 55 00:02:45.599 --> 00:02:45.919 a star? 56 00:02:46.319 --> 00:02:48.039 So it has to do with the density and the 57 00:02:48.120 --> 00:02:52.039 extreme proximity. Imagine a star very similar to our own Sun, 58 00:02:52.639 --> 00:02:55.159 just tracing a path through a galaxy. 59 00:02:54.800 --> 00:02:56.080 Okay, tracing its path. 60 00:02:55.960 --> 00:02:59.479 Over millions of years. Its orbit happens to drift a 61 00:02:59.479 --> 00:03:05.520 little too close to this hidden million solar mass black. 62 00:03:05.280 --> 00:03:07.080 Hole, just a little too close. 63 00:03:06.960 --> 00:03:09.759 Right, And because a black hole is so incredibly dense, 64 00:03:09.919 --> 00:03:12.560 the star can get extremely close to the center of 65 00:03:12.599 --> 00:03:15.159 that mass without hitting a physical surface. 66 00:03:14.879 --> 00:03:17.080 Because it's a singularity, not a giant rock. 67 00:03:17.319 --> 00:03:20.680 Yes, So as it approaches the gravitational poll on the 68 00:03:20.719 --> 00:03:23.759 side of the star facing the black hole becomes exponentially 69 00:03:23.800 --> 00:03:26.159 stronger than the pole on the far side of the star. 70 00:03:26.360 --> 00:03:28.639 Oh well, okay, so if the star is say a 71 00:03:28.719 --> 00:03:31.719 million miles wide, the front edge of the star is 72 00:03:31.759 --> 00:03:35.479 a million miles deeper into the black hole's gravity well than. 73 00:03:35.400 --> 00:03:38.840 The back edge precisely, And that difference in gravitational pull 74 00:03:38.919 --> 00:03:41.639 across the diameter of the star that is what we 75 00:03:41.680 --> 00:03:42.879 call the tidal force. 76 00:03:42.919 --> 00:03:45.000 Like the tides on Earth, but cranked up to. 77 00:03:45.039 --> 00:03:49.120 A trillion exactly like that, and eventually that tidal force 78 00:03:49.479 --> 00:03:52.360 exceeds the star's own internal gravity. 79 00:03:52.599 --> 00:03:55.039 The force that's holding the star together is a burning 80 00:03:55.080 --> 00:03:56.000 sphere of plasma. 81 00:03:56.479 --> 00:03:59.159 Yeah, that force is simply overwhelmed by the difference in 82 00:03:59.199 --> 00:03:59.919 the black holes. 83 00:04:00.520 --> 00:04:02.520 So the star doesn't just bump into it like a 84 00:04:02.520 --> 00:04:05.240 car crash, No, not at all. The front is yank 85 00:04:05.360 --> 00:04:08.400 so much harder than the back that the star simply 86 00:04:08.439 --> 00:04:11.560 cannot hold itself together. It fails structurally. 87 00:04:11.639 --> 00:04:15.280 It is literally torn apart. The term astrophysicists sometimes use 88 00:04:15.479 --> 00:04:17.199 is spaghettification. 89 00:04:17.839 --> 00:04:22.360 Spaghettification that sounds a bit whimsical for an absolute categorism. 90 00:04:22.399 --> 00:04:24.759 Well I know it really does, but it's accurate. The 91 00:04:24.800 --> 00:04:29.120 stars stretched into a long, thin stream of superheated stellar 92 00:04:29.160 --> 00:04:32.160 material like a noodle, like a noodle of plasma. Yeah, 93 00:04:32.720 --> 00:04:35.560 but what happens next is what makes this detectable to 94 00:04:35.680 --> 00:04:36.959 us here on Earth, because. 95 00:04:36.720 --> 00:04:38.800 It doesn't just quietly fall straight down into the void. 96 00:04:38.959 --> 00:04:41.680 No, it definitely doesn't. The crumbs of the splintering star, 97 00:04:41.800 --> 00:04:45.199 this immense volume of gas and plasma, they get caught 98 00:04:45.279 --> 00:04:47.319 in the black hole's gravitational grip. 99 00:04:47.160 --> 00:04:48.040 And they start to orbit. 100 00:04:48.319 --> 00:04:50.800 They do. They begin to swirl around the black hole, 101 00:04:51.160 --> 00:04:52.959 forming what we call an accretion disc. 102 00:04:53.120 --> 00:04:56.360 Okay, so it's like water circling a drain, very similar, Yes, 103 00:04:56.560 --> 00:04:59.560 but the drain is a bottomless pit in space time, 104 00:05:00.120 --> 00:05:03.879 and the water is superheated plasma moving at what a 105 00:05:03.959 --> 00:05:05.319 fraction of the speed of light. 106 00:05:05.279 --> 00:05:07.800 A significant fraction of the speed of light, and that 107 00:05:07.879 --> 00:05:09.399 speed is the key to everything. 108 00:05:09.639 --> 00:05:11.360 Why is the speed so important? 109 00:05:11.560 --> 00:05:15.360 Because the material is orbiting so incredibly fast. The friction 110 00:05:15.480 --> 00:05:19.199 within the gas is unimaginable friction in space. Yeah. As 111 00:05:19.199 --> 00:05:21.480 the layers of plasma rub against each other in that 112 00:05:21.560 --> 00:05:24.519 swirling disc, they undergo intense compression. 113 00:05:24.079 --> 00:05:26.079 And friction, which generates heat. 114 00:05:26.240 --> 00:05:30.000 It heats the material to temperatures that defy human comprehension. 115 00:05:30.199 --> 00:05:31.959 We're talking millions of degrees. 116 00:05:32.160 --> 00:05:34.439 Millions of degrees. That is insane, it is. 117 00:05:34.560 --> 00:05:39.399 And this heat creates an incredibly brilliant glow, radiating intense 118 00:05:39.480 --> 00:05:42.600 ultraviolet light and X rays across the cosmos. 119 00:05:42.759 --> 00:05:46.560 It's basically screaming its existence out into the universe exactly. 120 00:05:47.079 --> 00:05:51.040 And furthermore, the immense magnetic fields and the rotational energy 121 00:05:51.079 --> 00:05:53.639 involved in this whole process can cause the black hole 122 00:05:53.720 --> 00:05:56.600 to launch a relativistic jet into space. 123 00:05:57.279 --> 00:05:59.079 A relativistic jet, what is that? 124 00:05:59.360 --> 00:06:03.240 It's basic a highly concentrated beam of energy and matter 125 00:06:03.600 --> 00:06:06.959 shooting outward along the poles of the black hole, moving 126 00:06:07.000 --> 00:06:08.319 at nearly the speed of light. 127 00:06:08.560 --> 00:06:12.759 So it's like a cosmic lighthouse beam. It's the universe's 128 00:06:12.800 --> 00:06:14.240 most dramatic dinner bell. 129 00:06:14.519 --> 00:06:15.639 That's a great way to put it. 130 00:06:15.720 --> 00:06:19.079 Because black holes themselves emit zero light. I mean, you 131 00:06:19.079 --> 00:06:20.959 could be looking right at one and see nothing but 132 00:06:21.000 --> 00:06:22.000 the darkness of space. 133 00:06:22.199 --> 00:06:24.600 Right. They are functionally invisible. 134 00:06:24.279 --> 00:06:28.160 But this tde, this destruction of the star, completely lights 135 00:06:28.240 --> 00:06:28.759 up the dark. 136 00:06:29.000 --> 00:06:33.040 Assistant Professor igor Andreoni down at UNC Chapel Hill perfectly 137 00:06:33.160 --> 00:06:36.519 describe these events. He called them cosmic billboards. 138 00:06:36.680 --> 00:06:38.680 Cosmic billboards, I like that. 139 00:06:38.800 --> 00:06:42.040 Yeah, because they are quite literally advertising the presence of 140 00:06:42.040 --> 00:06:45.560 something that would otherwise remain completely stubbornly invisible. 141 00:06:45.120 --> 00:06:46.399 Which is huge for astronomy. 142 00:06:46.639 --> 00:06:49.839 It's a scientific gold mine. Catching these events in the 143 00:06:49.879 --> 00:06:54.120 act illuminates the actual mechanics of how massive black holes feed. 144 00:06:54.199 --> 00:06:57.399 Okay, but if we are just sitting around waiting for 145 00:06:57.480 --> 00:07:00.639 a star to accidentally bump into an invisible black hole, 146 00:07:01.360 --> 00:07:03.040 how often does that actually happen? 147 00:07:03.360 --> 00:07:05.399 Well, space is famously. 148 00:07:05.240 --> 00:07:07.720 Very empty, right, so it can't be that often. 149 00:07:07.800 --> 00:07:11.800 It is extraordinarily rare. On average, a tidal disruption event 150 00:07:11.920 --> 00:07:15.399 happens only once every one hundred thousand years anywhere in 151 00:07:15.439 --> 00:07:16.240 a given galaxy. 152 00:07:16.319 --> 00:07:19.360 Wait, wait, once every one hundred thousand years for a 153 00:07:19.399 --> 00:07:20.160 whole galaxy. 154 00:07:20.279 --> 00:07:21.240 That is the average rate. 155 00:07:21.360 --> 00:07:24.160 Yes, but a galaxy has billions of stars, you're telling 156 00:07:24.240 --> 00:07:27.399 me at billions of stars circling around, this crash only 157 00:07:27.480 --> 00:07:29.480 happens once every hundred millennia. 158 00:07:29.519 --> 00:07:31.879 It is a true testament to exactly what you just said. 159 00:07:32.079 --> 00:07:36.600 Space is incredibly empty. The distances between stars are vast, 160 00:07:36.720 --> 00:07:39.920 unimaginably vast, and the distances between a star and a 161 00:07:39.920 --> 00:07:44.360 central black hole are even vaster. The orbital alignment required 162 00:07:44.399 --> 00:07:47.160 for a star to perfectly cross that fatal threshold, what 163 00:07:47.199 --> 00:07:50.920 we call the title radius, is mathematically highly improbable. 164 00:07:50.959 --> 00:07:52.839 So it can't just be passing through the neighborhood. 165 00:07:52.959 --> 00:07:57.160 No, It's specific trajectory has to intersect a very precise, 166 00:07:57.600 --> 00:08:00.199 very narrow zone right around the block. 167 00:08:01.160 --> 00:08:04.480 To put that one hundred thousand year timeline and perspective 168 00:08:04.480 --> 00:08:09.480 for you listening, one hundred thousand years ago, anatomically modern 169 00:08:09.600 --> 00:08:13.720 humans were just starting to seriously migrate out of Africa. 170 00:08:13.879 --> 00:08:15.360 It's a massive span of time. 171 00:08:15.560 --> 00:08:18.720 Neanderthals were still the dominant hominins in Europe back then. 172 00:08:19.399 --> 00:08:22.040 We've gone from stone tools to quantum computers in the 173 00:08:22.079 --> 00:08:25.279 time it takes for a single galaxy to produce one 174 00:08:25.279 --> 00:08:26.519 of these flashes. 175 00:08:26.120 --> 00:08:28.879 Which is exactly why in the past decade of intensive 176 00:08:28.879 --> 00:08:33.080 modern astronomy, with all our advanced telescopes constantly scanning the skies, 177 00:08:33.399 --> 00:08:35.720 astronomers have only identified a little over one hundred of 178 00:08:35.720 --> 00:08:37.240 these TDEs in total. 179 00:08:37.000 --> 00:08:39.519 One hundred across millions of galaxies. 180 00:08:39.559 --> 00:08:42.000 Across the millions of galaxies we can actively observe. 181 00:08:42.120 --> 00:08:44.879 Yes, it makes me think of an analogy. Let's hear it. Okay, 182 00:08:45.159 --> 00:08:48.320 imagine you are in a massive pitch black warehouse. You 183 00:08:48.399 --> 00:08:50.960 have absolutely no idea what's in the room, but you 184 00:08:51.000 --> 00:08:54.720 suspect there's a giant, invisible spinning fan blades somewhere in there. Okay, 185 00:08:54.759 --> 00:08:57.799 a dangerous room, very and you can't use a flashlight, 186 00:08:58.039 --> 00:09:00.559 you can't make a sound. The only way you can 187 00:09:00.639 --> 00:09:04.120 find that fan blade is by taking a glowing, exploding 188 00:09:04.200 --> 00:09:06.440 paint bomb and tossing it into the dark. 189 00:09:06.519 --> 00:09:07.879 I see where this is going, right. 190 00:09:08.080 --> 00:09:10.879 If you toss it and it hits the floor, nothing happens. 191 00:09:10.919 --> 00:09:13.559 If you toss it and hits a wall, nothing happens. 192 00:09:13.240 --> 00:09:14.960 Because it's not hitting the target exactly. 193 00:09:15.279 --> 00:09:17.440 But if you just happen to toss that paint bomb 194 00:09:17.519 --> 00:09:21.279 perfectly into the spinning blades, boom, it shred The paint 195 00:09:21.279 --> 00:09:25.759 is violently shredded. It heats up, it splatters everywhere, and suddenly, 196 00:09:25.919 --> 00:09:28.799 for just a brief few weeks or months, the destruction 197 00:09:28.879 --> 00:09:32.960 of the paint reveals the exact shape, location, and violence 198 00:09:33.000 --> 00:09:34.080 of the monster in the dark. 199 00:09:34.279 --> 00:09:38.159 That is a highly accurate visualization. Actually, the star is 200 00:09:38.200 --> 00:09:41.200 your paint bomb, right. The destruction of the star is 201 00:09:41.200 --> 00:09:44.320 the only mechanism that renders the invisible fan blade. The 202 00:09:44.360 --> 00:09:46.159 black hole temporarily visible. 203 00:09:46.240 --> 00:09:48.480 But here's the thing, fighting one of these paint BOMs. 204 00:09:48.519 --> 00:09:51.879 Finding a TDE is not the real paradigm shift here today, 205 00:09:51.960 --> 00:09:54.360 is it. No, it's not, because we found one hundred 206 00:09:54.399 --> 00:09:58.360 of them before. The universe breaking mystery. Here is where 207 00:09:58.759 --> 00:10:01.039 this specific paint bam went off. 208 00:10:01.120 --> 00:10:05.120 Which brings us to this specific event designated as TDE 209 00:10:05.679 --> 00:10:07.759 twenty twenty five ABCR. 210 00:10:08.320 --> 00:10:08.879 Catch you name? 211 00:10:09.320 --> 00:10:11.279 They always are in astronomy. 212 00:10:10.720 --> 00:10:14.080 So researchers track this massive flare to a nearby galaxy. 213 00:10:14.480 --> 00:10:17.159 It doesn't even catch your very poetic catalog name. 214 00:10:17.320 --> 00:10:19.679 Oh why is a JJ zero one four sixty five 215 00:10:19.799 --> 00:10:23.399 six point zero four one five two two fourteen point seven? 216 00:10:23.480 --> 00:10:25.639 Wow? You memorized that. We'll just call it the wiser 217 00:10:25.720 --> 00:10:26.399 galaxy for sure? 218 00:10:26.440 --> 00:10:27.000 That idea. 219 00:10:27.480 --> 00:10:30.120 Usually when we see a TDE, it's dead center in 220 00:10:30.159 --> 00:10:33.240 the galaxy, right, almost always. But TDE twenty twenty five 221 00:10:33.279 --> 00:10:35.639 ABCR happened thirty thousand light years. 222 00:10:35.519 --> 00:10:38.559 Away from the center, which represents the farthest offset ever 223 00:10:38.639 --> 00:10:41.320 observed for an optically discovered title disruption event. 224 00:10:41.480 --> 00:10:44.480 Thirty thousand light years. That's a massive distance. 225 00:10:44.200 --> 00:10:46.840 It is, and it breaks a fundamental rule that astronomers 226 00:10:46.840 --> 00:10:48.480 have operated under for a very long time. 227 00:10:48.519 --> 00:10:49.519 Which rule is that well. 228 00:10:49.600 --> 00:10:52.320 Jonathan Carney, who's a PhD student in physics and astronomy 229 00:10:52.320 --> 00:10:55.399 at UNC Chapel Hill, pointed this out very clearly. He 230 00:10:55.519 --> 00:10:58.120 noted that almost every title disruption event we have ever 231 00:10:58.200 --> 00:11:01.360 observed has occurred at the absolute sence h of a galaxy. 232 00:11:00.960 --> 00:11:02.840 Because that is where the giant black holes live. 233 00:11:03.080 --> 00:11:07.840 Exactly. The galactic nucleus is where the supermassive black holes reside. 234 00:11:08.200 --> 00:11:11.480 It's where the gravitational well of the galaxy is the deepest. 235 00:11:11.600 --> 00:11:14.200 It's like the drain at the bottom of a massive sink, right. 236 00:11:14.279 --> 00:11:18.240 It's where the most matter has accumulated over billions of years. 237 00:11:18.759 --> 00:11:22.000 That is where we expect the biggest monsters to be. 238 00:11:22.360 --> 00:11:26.399 So to find a tidal disruption event tens of thousands 239 00:11:26.399 --> 00:11:28.240 of light years away from the center. 240 00:11:28.159 --> 00:11:30.799 It implies there is a massive black hole lurking in 241 00:11:30.840 --> 00:11:34.240 a place we would normally never ever expect to find one. 242 00:11:34.360 --> 00:11:36.399 I have to stop you here, though, because the scale 243 00:11:36.440 --> 00:11:38.240 and the physics are kind of messing with my head. 244 00:11:38.360 --> 00:11:41.360 How So, the black hole responsible for this event is 245 00:11:41.480 --> 00:11:45.039 estimated to be roughly one million times the mass of 246 00:11:45.039 --> 00:11:47.919 our sun one million solar. 247 00:11:47.559 --> 00:11:49.279 Masses that is the current estimate. 248 00:11:49.360 --> 00:11:51.559 Yes, how on Earth do you hide something with a 249 00:11:51.600 --> 00:11:54.519 million solar masses in the quiet suburbs of a galaxy? 250 00:11:54.679 --> 00:11:56.759 I mean, I feel like it's gravity would just be 251 00:11:56.919 --> 00:11:58.440 completely tearing the neighborhood apart. 252 00:11:58.559 --> 00:12:00.440 It's a fair assumption to make be like. 253 00:12:00.440 --> 00:12:03.639 A cosmic vacuum cleaner when we notice all the stars 254 00:12:03.679 --> 00:12:07.039 around it swirling down a drain before a TD even happens. 255 00:12:07.360 --> 00:12:10.399 It is a very common misconception about black holes, this 256 00:12:10.519 --> 00:12:13.320 idea that they are cosmic vacuum cleaners. 257 00:12:12.960 --> 00:12:15.840 Because pop culture always shows them sucking everything in. 258 00:12:16.120 --> 00:12:19.879 Right, we assume something that massive must be inherently disruptive, 259 00:12:20.039 --> 00:12:23.000 just constantly pulling in everything around it. But you really 260 00:12:23.080 --> 00:12:24.360 have to remember two things here. 261 00:12:24.480 --> 00:12:25.320 Okay, what are they? 262 00:12:25.600 --> 00:12:28.759 First the sheer scale of the space we are talking about, 263 00:12:29.120 --> 00:12:32.080 and second, the inverse square law of gravity. 264 00:12:32.200 --> 00:12:34.639 Okay, let's break down the inverse square law. Yeah, that 265 00:12:34.720 --> 00:12:37.480 sounds like the actual key to this whole hiding trick. 266 00:12:37.600 --> 00:12:42.120 It absolutely is. Gravity is entirely dependent on distance. The 267 00:12:42.159 --> 00:12:44.879 inverse square law basically states that if you double the 268 00:12:44.919 --> 00:12:49.039 distance between two objects, the gravitational force doesn't just drop 269 00:12:49.120 --> 00:12:49.639 by half. 270 00:12:49.960 --> 00:12:50.559 It doesn't. 271 00:12:50.879 --> 00:12:53.759 No, it drops by a factor of four. It weakens 272 00:12:53.759 --> 00:12:56.440 exponentially the further away you get. Oh wow, if you 273 00:12:56.480 --> 00:12:58.840 triple the distance, the force is nine times weaker. 274 00:12:58.960 --> 00:13:01.679 So gravity basically falls off a cliff once you take 275 00:13:01.720 --> 00:13:03.120 a few steps away from the source. 276 00:13:03.399 --> 00:13:06.519 Precisely, let me give you a local example. If you 277 00:13:06.600 --> 00:13:09.200 were to replace our own Sun right now with a 278 00:13:09.200 --> 00:13:13.480 black hole of the exact same mass, one solar mass, 279 00:13:14.320 --> 00:13:15.679 Earth would not get sucked in. 280 00:13:16.120 --> 00:13:19.399 Wait, really, we wouldn't just spiral to our doom, not 281 00:13:19.519 --> 00:13:19.840 at all. 282 00:13:19.879 --> 00:13:22.360 The Earth would continue orbiting in the exact same path 283 00:13:22.440 --> 00:13:24.440 in exactly three hundred and sixty five. 284 00:13:24.360 --> 00:13:26.000 Days because the mass hasn't changed. 285 00:13:26.279 --> 00:13:28.919 Because the mass hasn't changed, and our distance hasn't changed. 286 00:13:29.000 --> 00:13:30.960 The only difference is that we'd all freeze and it 287 00:13:30.960 --> 00:13:32.320 would get very very dark. 288 00:13:32.519 --> 00:13:34.759 It would be a bad day for life on Earth. Yes, 289 00:13:35.120 --> 00:13:37.679 but gravitationally, nothing changes. 290 00:13:37.840 --> 00:13:40.080 So let's apply that to this wandering monster in the 291 00:13:40.080 --> 00:13:43.600 wiser galaxy. It has the mass of a million suns. 292 00:13:43.480 --> 00:13:46.759 Right, and a million solar masses is immense compared to 293 00:13:46.799 --> 00:13:49.480 our Sun, obviously, but on a galactic scale, it's just 294 00:13:49.519 --> 00:13:50.679 a drop in the ocean. 295 00:13:50.759 --> 00:13:53.000 Really, a million suns is a drop the. 296 00:13:53.080 --> 00:13:56.600 Entire galaxy weighs billions or even trillions of solar masses 297 00:13:57.120 --> 00:14:00.000 thirty thousand light years from the center. Puts this black 298 00:14:00.080 --> 00:14:02.679 hole out in the outer galactic disc, or maybe even 299 00:14:02.679 --> 00:14:03.440 the halo. 300 00:14:03.240 --> 00:14:05.240 Which is the sparsely populated part of town. 301 00:14:05.600 --> 00:14:08.480 Exactly. These are regions where the density of stars is 302 00:14:08.519 --> 00:14:11.720 significantly lower than in the packed galactic core. 303 00:14:11.559 --> 00:14:13.840 So it's not packed like sardines out there. The stars 304 00:14:13.879 --> 00:14:15.879 have a lot of elbow room, lots of rooms. 305 00:14:15.919 --> 00:14:18.639 So because of that inverse square law we just talked about, 306 00:14:19.240 --> 00:14:24.279 unless a star crosses that very specific, very narrow threshold 307 00:14:24.360 --> 00:14:27.799 right next to the black hole's event horizon, it will 308 00:14:27.799 --> 00:14:29.399 simply orbit the black hole. 309 00:14:29.240 --> 00:14:31.159 Safely or just pass right by it. 310 00:14:31.279 --> 00:14:35.080 Yes, completely unaffected in any catastrophic way. 311 00:14:35.360 --> 00:14:37.559 So it really isn't a vacuum cleaner at all. It's 312 00:14:37.559 --> 00:14:41.519 more like, Okay, it's like a really really deep pothole 313 00:14:42.240 --> 00:14:46.080 on a very wide, empty, dark highway. I like that, Like, 314 00:14:46.080 --> 00:14:48.000 if you don't drive your tire directly over it, you're 315 00:14:48.000 --> 00:14:49.480 totally fine. You don't even know it's there. 316 00:14:49.559 --> 00:14:51.120 That is a perfect way to look at it, and 317 00:14:51.240 --> 00:14:53.799 scientists have actually theorized for a while that these wandering 318 00:14:53.840 --> 00:14:56.360 black holes likely exist in massive galaxies. 319 00:14:56.480 --> 00:14:57.799 They suspected they were out there. 320 00:14:57.840 --> 00:15:02.200 Oh, definitely the mathematics when the really complex computer simulations 321 00:15:02.200 --> 00:15:05.679 of galactic evolution strongly suggest they should be out there 322 00:15:05.720 --> 00:15:06.799 wandering around. 323 00:15:06.919 --> 00:15:09.200 But knowing they exist in a computer model and actually 324 00:15:09.200 --> 00:15:12.039 finding one in the dark are two very different. 325 00:15:11.759 --> 00:15:16.919 Things, extremely different. As Jonathan Carney highlighted, they are notoriously 326 00:15:16.960 --> 00:15:20.600 difficult to study because unless they are actively feeding, unless 327 00:15:20.639 --> 00:15:23.559 they briefly disrupt a star like this one, did, they 328 00:15:23.600 --> 00:15:25.440 produce absolutely no light. 329 00:15:25.679 --> 00:15:28.759 They're perfectly camouflaged against the darkness of empty. 330 00:15:28.480 --> 00:15:29.840 Space, literally invisible. 331 00:15:29.960 --> 00:15:33.919 Okay, So if a one million solar mass black hole 332 00:15:34.240 --> 00:15:38.159 does not naturally belong in the galactic suburbs, if it's 333 00:15:38.159 --> 00:15:40.360 supposed to be downtown in the galactic core where it 334 00:15:40.399 --> 00:15:43.000 was born, how in the universe did he get thirty 335 00:15:43.039 --> 00:15:44.159 thousand light years away? 336 00:15:44.320 --> 00:15:45.360 That is the big question. 337 00:15:45.519 --> 00:15:48.000 I mean, what could possibly have the leverage to move 338 00:15:48.039 --> 00:15:50.960 an object that weighs a million times more than our sun. 339 00:15:51.080 --> 00:15:55.159 Well. Astrophysics offers two leading theoretical scenarios for how a 340 00:15:55.200 --> 00:15:59.000 supermassive black hole becomes a wanderer, A rogue drifting far 341 00:15:59.039 --> 00:16:02.200 from home to hear them. Both scenarios are rooted in 342 00:16:02.279 --> 00:16:06.279 immense violence and cosmic scale upheaval. The first theory proposes 343 00:16:06.279 --> 00:16:09.320 that this black hole is essentially a remnant left behind 344 00:16:09.399 --> 00:16:12.159 after a massive galactic merger in the distant past. 345 00:16:12.399 --> 00:16:14.840 Let's talk about a galactic merger for a second. We're 346 00:16:14.840 --> 00:16:17.879 talking about two entirely separate galaxies colliding. 347 00:16:17.519 --> 00:16:21.480 With each other, right, Yes, a cosmic collision. Picture a 348 00:16:21.600 --> 00:16:26.480 massive galaxy in a smaller satellite galaxy nearby. Over billions 349 00:16:26.480 --> 00:16:30.720 of years, their mutual gravitational attractions slowly dries them. 350 00:16:30.559 --> 00:16:33.240 Together billions of years. Yeah, so this is not a 351 00:16:33.240 --> 00:16:33.960 fast crash. 352 00:16:34.360 --> 00:16:39.480 No, it is an incredibly slow, majestic, and entirely destructive process. 353 00:16:39.759 --> 00:16:43.320 As the two galaxies merge, their outer halos touch first, 354 00:16:43.600 --> 00:16:44.120 what happens? 355 00:16:44.159 --> 00:16:44.320 Then? 356 00:16:44.559 --> 00:16:48.159 Gas clouds collide, which compresses the gas and ignites massive 357 00:16:48.279 --> 00:16:51.759 bursts of new star formation. It would look like fireworks 358 00:16:51.759 --> 00:16:52.840 on a cosmic scale. 359 00:16:52.960 --> 00:16:55.440 But do the actual stars crash into each other? 360 00:16:55.519 --> 00:16:59.240 Surprisingly? No, The stars themselves rarely collide because of the 361 00:16:59.320 --> 00:17:02.759 vast distance between them, but their orbits are thrown into 362 00:17:02.759 --> 00:17:04.440 complete and utter chaos. 363 00:17:04.519 --> 00:17:06.960 Okay, but what happens to the black holes because both 364 00:17:07.000 --> 00:17:09.799 of these galaxies started with their own supermassive black hole 365 00:17:09.839 --> 00:17:11.480 in their respective centers, right. 366 00:17:11.400 --> 00:17:12.319 Most galaxies do. 367 00:17:12.480 --> 00:17:12.759 Yes. 368 00:17:12.839 --> 00:17:16.119 Now, in a perfect symmetrical merger, the two central black 369 00:17:16.119 --> 00:17:19.759 holes would undergo a process called dynamical friction. Dynamical friction, 370 00:17:20.119 --> 00:17:22.559 they would interact with the gas and stars around them, 371 00:17:22.599 --> 00:17:26.079 slowly losing orbital energy, and they'd gradually sync to the 372 00:17:26.079 --> 00:17:29.200 center of the newly combined larger galaxy. 373 00:17:28.799 --> 00:17:31.839 So they sort of spiral down the new drain together exactly. 374 00:17:32.240 --> 00:17:34.759 Eventually they would orbit each other in a binary pair, 375 00:17:35.240 --> 00:17:38.839 and over millions of years, merge into one even larger 376 00:17:39.039 --> 00:17:40.519 supermassive black hole. 377 00:17:40.680 --> 00:17:44.319 That sounds very neat and orderly, but I'm guessing space 378 00:17:44.359 --> 00:17:45.400 isn't always that tidy. 379 00:17:45.519 --> 00:17:49.839 Far from it. Mergers are very messy asymmetrical events. Sometimes 380 00:17:49.880 --> 00:17:52.759 the smaller galaxy is essentially stripped apart before it even 381 00:17:52.799 --> 00:17:53.559 reaches the center. 382 00:17:53.680 --> 00:17:54.279 Stripped apart. 383 00:17:54.319 --> 00:17:57.839 How its outer layers of stars and gas are literally 384 00:17:57.880 --> 00:18:00.920 peeled away by the tidal forces of the larger. 385 00:18:00.640 --> 00:18:02.960 Galaxy, So it's just dismantled, right. 386 00:18:03.200 --> 00:18:05.759 And by the time the smaller galaxy is fully swallowed, 387 00:18:06.079 --> 00:18:09.440 its central black hole is left completely stranded because. 388 00:18:09.240 --> 00:18:11.079 All the stuff around it that was helping it sinc 389 00:18:11.240 --> 00:18:11.640 is gone. 390 00:18:11.880 --> 00:18:15.359 Yes, it loses its surrounding mass and never manages to 391 00:18:15.440 --> 00:18:18.519 sync to the new galactic core through that dynamical friction. 392 00:18:19.160 --> 00:18:22.119 It simply gets marooned out in the newly expanded outer 393 00:18:22.200 --> 00:18:23.640 halo of the merged. 394 00:18:23.359 --> 00:18:27.440 Galaxy, just orbiting aimlessly, just wandering. So it's basically the 395 00:18:27.559 --> 00:18:31.759 orphan heart of a dead, consumed galaxy, just floating through 396 00:18:31.759 --> 00:18:35.039 the outer ruins of its former home. That is incredibly 397 00:18:35.079 --> 00:18:36.240 poetic and kind of sad. 398 00:18:36.480 --> 00:18:39.759 It is a profound cosmic artifact of a billion year 399 00:18:39.799 --> 00:18:40.759 old collision. 400 00:18:40.799 --> 00:18:43.279 Okay, what's the second theory? Because you said there. 401 00:18:43.160 --> 00:18:45.799