1 00:00:02,689 --> 00:00:06,344 ROWE: You might have seen a boxing match on TV. 2 00:00:06,448 --> 00:00:08,965 Maybe you've even seen one live. 3 00:00:09,068 --> 00:00:12,965 But you have never seen a contest like this. 4 00:00:13,068 --> 00:00:18,551 Take your ringside seat to the fight of the cosmos. 5 00:00:18,655 --> 00:00:20,965 This is gonna be a wonderful fight to witness. 6 00:00:21,068 --> 00:00:23,413 But you'll want to be a few 7 00:00:23,517 --> 00:00:25,137 million billion light-years away. 8 00:00:25,241 --> 00:00:28,620 It's like being punched by the ghost of Muhammad Ali. 9 00:00:28,724 --> 00:00:30,206 You don't even see it coming. 10 00:00:30,310 --> 00:00:34,448 ROWE: Our fighters don't float like a butterfly or sting like 11 00:00:34,551 --> 00:00:39,413 a bee, but they can deliver the ultimate knockout blow. 12 00:00:39,517 --> 00:00:45,275 It is a soul-chilling, mind-crushing amount of energy. 13 00:00:45,379 --> 00:00:47,241 It's just unbelievable. 14 00:00:47,344 --> 00:00:50,793 ROWE: It's a fight between two supermassive black holes. 15 00:00:50,896 --> 00:00:53,551 Forget about the world heavyweight championships. 16 00:00:53,655 --> 00:00:56,586 This is the universe's heavyweight championships. 17 00:00:57,724 --> 00:00:59,827 ROWE: Get ready for the heavyweight 18 00:00:59,931 --> 00:01:01,758 championship of the universe. 19 00:01:18,034 --> 00:01:21,172 2021, scientists detect 20 00:01:21,275 --> 00:01:24,137 a gigantic rumble deep in space, 21 00:01:24,241 --> 00:01:27,137 a tsunami of gravitational waves, 22 00:01:27,241 --> 00:01:30,758 giant ripples racing across the universe. 23 00:01:30,862 --> 00:01:33,862 MINGARELLI: Gravitational waves that big have to 24 00:01:33,965 --> 00:01:37,724 come from a giant, cataclysmic event. 25 00:01:37,827 --> 00:01:41,379 The universe is immense and full of very 26 00:01:41,482 --> 00:01:44,517 violent events that are happening every single day. 27 00:01:44,620 --> 00:01:47,793 The universe is a scary place. 28 00:01:47,896 --> 00:01:50,827 There is violence everywhere we look. 29 00:01:52,103 --> 00:01:55,172 ROWE: The growls and roars are clues about 30 00:01:55,275 --> 00:01:58,724 the ultimate cosmic brawl, 31 00:01:58,827 --> 00:02:01,931 the most violent event in the universe. 32 00:02:04,275 --> 00:02:07,965 But we don't know where they're coming from. 33 00:02:08,068 --> 00:02:09,655 SUTTER: Imagine a storm is coming 34 00:02:09,758 --> 00:02:10,689 in the middle of the night. 35 00:02:10,793 --> 00:02:12,068 You can't see the storm, 36 00:02:12,172 --> 00:02:15,344 you can't see the lightning, but you can hear that rumble of 37 00:02:15,448 --> 00:02:19,965 the distant thunder, and you know that it's coming. 38 00:02:20,068 --> 00:02:23,655 ROWE: This distant rumble of gravitational waves 39 00:02:23,758 --> 00:02:26,172 is like the footwork of heavyweights 40 00:02:26,275 --> 00:02:28,689 pounding the canvas of the boxing ring. 41 00:02:29,965 --> 00:02:32,689 The waves are caused by something massive 42 00:02:32,793 --> 00:02:34,310 throwing its weight around. 43 00:02:36,172 --> 00:02:39,827 It's not the first time we've detected gravitational waves. 44 00:02:43,068 --> 00:02:44,379 Our experiments have picked up 45 00:02:44,482 --> 00:02:47,310 the signal of two small stellar mass 46 00:02:47,413 --> 00:02:49,448 black holes colliding. 47 00:02:49,551 --> 00:02:54,172 These waves are high-pitched and ring like a boxing bell. 48 00:02:54,275 --> 00:02:58,413 The deep space growl is a much lower frequency, 49 00:02:58,517 --> 00:03:00,103 like the roar of a crowd. 50 00:03:00,206 --> 00:03:02,724 [crowd chanting] 51 00:03:02,827 --> 00:03:04,379 MINGARELLI: The difference in frequencies 52 00:03:04,482 --> 00:03:07,137 would be even more exaggerated than the difference 53 00:03:07,241 --> 00:03:10,620 between a sparrow chirping and the sound coming from 54 00:03:10,724 --> 00:03:12,482 a blue whale underwater. 55 00:03:12,586 --> 00:03:16,655 It would be orders of magnitude more different than that. 56 00:03:19,000 --> 00:03:21,482 ROWE: The low frequency of the deep space rumble 57 00:03:21,586 --> 00:03:24,241 tells us that the waves are colossal. 58 00:03:25,551 --> 00:03:28,448 MINGARELLI: Imagine throwing a stone in the water 59 00:03:28,551 --> 00:03:30,379 and watching the little ripples come out. 60 00:03:30,482 --> 00:03:33,586 Now imagine throwing in a boulder a billion times 61 00:03:33,689 --> 00:03:34,758 more massive 62 00:03:34,862 --> 00:03:37,620 and watching the huge waves that come from that. 63 00:03:37,724 --> 00:03:39,862 Those are the waves that we're looking at. 64 00:03:41,517 --> 00:03:43,172 These are more difficult to detect, 65 00:03:43,275 --> 00:03:45,862 because the waves are so big. 66 00:03:45,965 --> 00:03:50,000 One of their wavelengths is about 15 light-years. 67 00:03:50,103 --> 00:03:51,862 You could wait for 15 years 68 00:03:51,965 --> 00:03:54,827 and only have one wavelength go by the Earth. 69 00:03:56,068 --> 00:03:58,758 ROWE: The waves are too big for an earthbound detector 70 00:03:58,862 --> 00:04:00,310 to pick up. 71 00:04:00,413 --> 00:04:03,862 So, to search for the source of these giant waves, 72 00:04:03,965 --> 00:04:06,275 Chiara Mingarelli and her team 73 00:04:06,379 --> 00:04:10,379 use a detector already in space, 74 00:04:10,482 --> 00:04:12,103 something large enough to pick up 75 00:04:12,206 --> 00:04:14,931 these galactic heavyweights, 76 00:04:15,034 --> 00:04:18,896 spinning dead stars called pulsars. 77 00:04:19,000 --> 00:04:23,448 MINGARELLI: Our galaxy is awash with pulsars. 78 00:04:23,551 --> 00:04:26,172 Now, they're called pulsars because they pulsate 79 00:04:26,275 --> 00:04:29,241 very regularly-- they're like cosmic lighthouses. 80 00:04:29,344 --> 00:04:31,724 ROWE: The lighthouse beams are so regular, 81 00:04:31,827 --> 00:04:33,344 you can set your watch by them. 82 00:04:34,758 --> 00:04:38,344 But when a huge gravitational wave hits them, 83 00:04:38,448 --> 00:04:41,241 the timing gets knocked out of whack. 84 00:04:41,344 --> 00:04:44,931 PLAIT: That pulsar is going to basically rock back and forth 85 00:04:45,034 --> 00:04:46,931 and that's going to change the timing 86 00:04:47,034 --> 00:04:50,241 of the pulses that we measure from that object. 87 00:04:50,344 --> 00:04:53,931 ROWE: To identify the source of the gravitational waves, 88 00:04:54,034 --> 00:04:58,896 Chiara and her team measure the wobbles of 100 pulsars, 89 00:04:59,000 --> 00:05:02,206 spread across light-years of space. 90 00:05:02,310 --> 00:05:06,241 MINGARELLI: It's like a tsunami, and the pulsars are 91 00:05:06,344 --> 00:05:08,655 like the buoys on the surface of the ocean. 92 00:05:08,758 --> 00:05:10,689 And as the tsunami passes by, 93 00:05:10,793 --> 00:05:12,586 we can watch all of them moving 94 00:05:12,689 --> 00:05:14,275 and shifting up and down. 95 00:05:14,379 --> 00:05:16,137 So our pulsar timing array 96 00:05:16,241 --> 00:05:18,689 is a gravitational wave warning system. 97 00:05:20,068 --> 00:05:22,344 ROWE: The pulsar array has identified 98 00:05:22,448 --> 00:05:25,655 the source of the tsunami of gravitational waves. 99 00:05:27,379 --> 00:05:29,448 The only thing we know of that can make these 100 00:05:29,551 --> 00:05:32,103 very long wavelength, [deep voice] very low pitch 101 00:05:32,206 --> 00:05:34,862 [normally] gravitational waves would be the collisions 102 00:05:34,965 --> 00:05:36,724 of supermassive black holes. 103 00:05:36,827 --> 00:05:38,827 MINGARELLI: They're massive, they're huge, 104 00:05:38,931 --> 00:05:41,034 and they know how to throw their weight around. 105 00:05:41,137 --> 00:05:44,413 Supermassive black hole binaries produce the loudest 106 00:05:44,517 --> 00:05:46,551 gravitational waves in the universe. 107 00:05:48,206 --> 00:05:50,724 ROWE: The gravitational wave signal revealed 108 00:05:50,827 --> 00:05:52,620 something extraordinary. 109 00:05:52,724 --> 00:05:55,206 MINGARELLI: It's not just gravitational waves coming 110 00:05:55,310 --> 00:05:57,896 from one black hole binary pair. 111 00:05:58,000 --> 00:05:59,482 It's actually from the cosmic 112 00:05:59,586 --> 00:06:03,241 population of supermassive black hole binaries. 113 00:06:04,620 --> 00:06:06,896 ROWE: Chiara and her team think there may be 114 00:06:07,000 --> 00:06:11,344 tens of thousands of heavyweight bouts going on. 115 00:06:11,448 --> 00:06:14,965 Now, the scientists want to pick out the sound of one 116 00:06:15,068 --> 00:06:19,965 single collision between two supermassive black holes from 117 00:06:20,068 --> 00:06:21,724 the background roar. 118 00:06:24,275 --> 00:06:26,137 MINGARELLI: If we were to hear 119 00:06:26,241 --> 00:06:28,068 a supermassive black hole merger, 120 00:06:28,172 --> 00:06:30,758 it would sound like a very low frequency growl. 121 00:06:30,862 --> 00:06:33,482 This "ooooooh" 122 00:06:33,586 --> 00:06:36,275 that would last about 25 million years. 123 00:06:36,379 --> 00:06:39,137 ROWE: To date, we haven't witnessed two supermassive 124 00:06:39,241 --> 00:06:42,000 black holes trading blows in real time. 125 00:06:42,103 --> 00:06:45,413 But we have seen events leading up 126 00:06:45,517 --> 00:06:47,137 to the championship bout. 127 00:06:47,241 --> 00:06:50,068 We've watched galaxies merge. 128 00:06:50,172 --> 00:06:51,586 We've seen stars explode. 129 00:06:51,689 --> 00:06:54,655 We've seen so many violent events in the universe. 130 00:06:54,758 --> 00:06:56,448 But we haven't seen this one. 131 00:06:56,551 --> 00:06:58,724 It's odd if you think about it. 132 00:06:58,827 --> 00:07:00,517 We haven't seen the biggest one. 133 00:07:00,620 --> 00:07:04,000 We haven't seen mergers between supermassive black holes. 134 00:07:04,103 --> 00:07:06,586 ROWE: But that may be about to change. 135 00:07:08,724 --> 00:07:12,517 Chiara predicts there are 112 fighters who are 136 00:07:12,620 --> 00:07:15,586 pumped up and ready to enter the ring. 137 00:07:18,379 --> 00:07:19,689 MINGARELLI: In the next five years, 138 00:07:19,793 --> 00:07:22,379 we should be able to detect at least one 139 00:07:22,482 --> 00:07:24,206 supermassive black hole merger. 140 00:07:24,310 --> 00:07:30,655 ROWE: It'll be the most violent event in the cosmos. 141 00:07:30,758 --> 00:07:32,793 Let's put that in context. 142 00:07:32,896 --> 00:07:37,241 We talk about how supernova are some of the most explosive, 143 00:07:37,344 --> 00:07:39,551 energetic things in our universe. 144 00:07:39,655 --> 00:07:42,620 Well, colliding supermassive black holes 145 00:07:42,724 --> 00:07:45,034 are a billion, billion, billion, 146 00:07:45,137 --> 00:07:48,896 billion times more energetic than a supernova. 147 00:07:49,000 --> 00:07:52,137 Think about all of the light being emitted by everything in 148 00:07:52,241 --> 00:07:55,448 the universe, every star, every galaxy. 149 00:07:55,551 --> 00:07:58,275 In one instant, two supermassive black holes 150 00:07:58,379 --> 00:08:02,620 colliding could release 100 million times that energy. 151 00:08:02,724 --> 00:08:06,000 Imagine being punched in the face by 152 00:08:06,103 --> 00:08:08,965 the biggest, baddest heavyweight of all time. 153 00:08:09,068 --> 00:08:11,793 Ouch. 154 00:08:11,896 --> 00:08:13,896 This is way bigger than that. 155 00:08:14,000 --> 00:08:17,620 ROWE: Where does all this energy come from? 156 00:08:17,724 --> 00:08:19,931 Surprisingly, it originates in 157 00:08:20,034 --> 00:08:22,758 the smallest atoms in the cosmos, 158 00:08:22,862 --> 00:08:26,275 in a story that dates back billions of years, 159 00:08:26,379 --> 00:08:29,689 all the way to the birth of the universe. 160 00:08:40,827 --> 00:08:41,896 ROWE: We're taking our seats for 161 00:08:42,000 --> 00:08:44,931 the most violent event in the universe, 162 00:08:45,034 --> 00:08:49,172 the collision of two supermassive black holes. 163 00:08:49,275 --> 00:08:51,000 We've never witnessed this cosmic 164 00:08:51,103 --> 00:08:52,724 heavyweight championship, 165 00:08:52,827 --> 00:08:56,241 but we can build up a picture of this epic fight by studying 166 00:08:56,344 --> 00:08:58,586 other weight classes with lighter fighters. 167 00:09:03,344 --> 00:09:07,655 2020-- the earthbound gravitational wave detector, 168 00:09:07,758 --> 00:09:09,275 LIGO, picks up 169 00:09:09,379 --> 00:09:12,275 the distinctive signal of a stellar mass 170 00:09:12,379 --> 00:09:13,344 black hole merger. 171 00:09:14,862 --> 00:09:19,758 What we saw was a black hole of 85 times the mass of our sun, 172 00:09:19,862 --> 00:09:23,034 and another black hole of 66 times the mass of our sun, 173 00:09:23,137 --> 00:09:27,068 smashing together to create a combined black hole. 174 00:09:27,172 --> 00:09:30,896 MINGARELLI: As someone who studies black hole mergers, 175 00:09:31,000 --> 00:09:32,862 this was a really exciting event. 176 00:09:32,965 --> 00:09:34,034 We're talking about 177 00:09:34,137 --> 00:09:36,551 the largest, the heaviest, the most massive 178 00:09:36,655 --> 00:09:39,275 black holes we have seen collide to date. 179 00:09:41,103 --> 00:09:43,137 ROWE: It may be the largest detection, 180 00:09:43,241 --> 00:09:45,172 but on a universal scale, 181 00:09:45,275 --> 00:09:48,793 it's still a small fry-- like lightweight boxers, 182 00:09:48,896 --> 00:09:51,620 the two black holes circle each other 183 00:09:51,724 --> 00:09:55,827 and emit low energy gravitational waves. 184 00:09:55,931 --> 00:09:58,379 This energy loss causes the black holes 185 00:09:58,482 --> 00:10:00,896 to spiral in together. 186 00:10:01,000 --> 00:10:04,793 Finally, they collide in a cosmos-shattering event, 187 00:10:06,586 --> 00:10:09,034 forming a single black hole 188 00:10:09,137 --> 00:10:13,172 and releasing a huge blast of gravitational waves. 189 00:10:13,275 --> 00:10:18,137 But when astronomers examine the single merged black hole, 190 00:10:18,241 --> 00:10:20,482 something doesn't add up. 191 00:10:20,586 --> 00:10:22,586 PONTZEN: If you take the combined mass of 192 00:10:22,689 --> 00:10:25,931 the two black holes, you get to 150 times 193 00:10:26,034 --> 00:10:27,379 the mass of our sun. 194 00:10:27,482 --> 00:10:30,724 But actually, the black hole that's left only has 195 00:10:30,827 --> 00:10:35,413 a mass of 142 times the mass of our sun. 196 00:10:35,517 --> 00:10:38,310 So the mass you have before the event does 197 00:10:38,413 --> 00:10:41,551 not equal the mass you have after the event. 198 00:10:41,655 --> 00:10:45,965 What happened to that missing eight solar masses? 199 00:10:46,068 --> 00:10:49,931 The way these black hole mergers work is very roughly 5 percent 200 00:10:50,034 --> 00:10:52,758 of the total mass of the system gets converted 201 00:10:52,862 --> 00:10:54,241 into energy. 202 00:10:54,344 --> 00:10:58,620 ROWE: It all comes down to E equals MC squared. 203 00:10:59,862 --> 00:11:02,379 This is that beautiful equation that Einstein 204 00:11:02,482 --> 00:11:04,827 told us-- E equals MC squared. 205 00:11:04,931 --> 00:11:07,896 E is the energy, and M is the mass. 206 00:11:08,000 --> 00:11:11,241 Einstein taught us that mass and energy are related. 207 00:11:11,344 --> 00:11:15,379 In fact, much of what we call mass is actually energy. 208 00:11:15,482 --> 00:11:18,448 ROWE: In this case, the violence of the collision 209 00:11:18,551 --> 00:11:23,172 transforms 18,000 trillion trillion tons 210 00:11:23,275 --> 00:11:27,275 of matter into an explosion of gravitational waves. 211 00:11:27,379 --> 00:11:30,068 SUTTER: In just a fraction of a second, 212 00:11:30,172 --> 00:11:35,758 eight suns worth of matter is converted into pure 213 00:11:35,862 --> 00:11:37,793 unadulterated energy. 214 00:11:37,896 --> 00:11:40,862 The amount of energy released was so great, that if you add 215 00:11:40,965 --> 00:11:43,793 up all the energy of all the stars burning in 216 00:11:43,896 --> 00:11:45,517 the universe, 217 00:11:45,620 --> 00:11:47,551 it was bigger than that. 218 00:11:47,655 --> 00:11:52,620 ROWE: This event was a collision between relative lightweights, 219 00:11:52,724 --> 00:11:55,862 two stellar mass black holes. 220 00:11:57,965 --> 00:12:00,241 To understand heavyweight bouts, 221 00:12:00,344 --> 00:12:05,413 we need to scale up to supermassive black holes. 222 00:12:08,034 --> 00:12:09,827 In the universe of sports, 223 00:12:09,931 --> 00:12:13,413 supermassive black holes are the heavyweight contenders. 224 00:12:13,517 --> 00:12:16,655 With these big black holes, size matters. 225 00:12:16,758 --> 00:12:18,206 The bigger the better. 226 00:12:18,310 --> 00:12:20,344 More mass means more energy, 227 00:12:20,448 --> 00:12:23,172 which means more destructive power. 228 00:12:23,275 --> 00:12:25,827 ROWE: We don't need to look too far to find 229 00:12:25,931 --> 00:12:27,862 this devastating muscle. 230 00:12:27,965 --> 00:12:30,862 This is M87 star, 231 00:12:30,965 --> 00:12:34,206 one of the largest supermassive black holes 232 00:12:34,310 --> 00:12:35,551 in our cosmic zip code. 233 00:12:36,862 --> 00:12:39,344 M87 star is huge. 234 00:12:39,448 --> 00:12:42,379 It weighs about six billion solar masses, 235 00:12:42,482 --> 00:12:43,862 about six billion suns, 236 00:12:43,965 --> 00:12:46,379 and it's the size of our solar system. 237 00:12:46,482 --> 00:12:50,034 ROWE: A collision between two 6-billion solar mass 238 00:12:50,137 --> 00:12:53,206 supermassive black holes would release around five 239 00:12:53,310 --> 00:12:57,241 times 10 to the power of 56 joules. 240 00:12:57,344 --> 00:13:01,206 So what's that mean in real world terms? 241 00:13:01,310 --> 00:13:04,655 It's hard to use words to express how much energy this is, 242 00:13:04,758 --> 00:13:07,413 and the numbers are so huge, they are almost meaningless. 243 00:13:07,517 --> 00:13:09,827 The only way I can really explain this is... 244 00:13:09,931 --> 00:13:11,586 [exaggerated scream] 245 00:13:13,724 --> 00:13:16,344 In physics, we have these comparisons 246 00:13:16,448 --> 00:13:17,620 so we can get a mental picture, 247 00:13:17,724 --> 00:13:20,413 but for something like this, there is no mental picture. 248 00:13:20,517 --> 00:13:23,000 That is so freaking big. 249 00:13:26,068 --> 00:13:28,137 ROWE: So where does this destructive 250 00:13:28,241 --> 00:13:31,000 mass and energy come from? 251 00:13:34,275 --> 00:13:37,344 It starts with the simplest ingredient-- 252 00:13:37,448 --> 00:13:38,896 hydrogen. 253 00:13:41,586 --> 00:13:46,068 Hydrogen is the basic building block of the universe. 254 00:13:46,172 --> 00:13:51,586 Each atom is tiny, but it contains a lot of energy. 255 00:13:51,689 --> 00:13:54,551 Hydrogen atoms contain a huge amount of energy, 256 00:13:54,655 --> 00:13:56,172 just like all matter does. 257 00:13:56,275 --> 00:13:57,827 And if it's unlocked in 258 00:13:57,931 --> 00:14:00,724 a certain way, there can be huge explosions. 259 00:14:03,724 --> 00:14:06,689 I mean, you take the mass contained simply in my hand, 260 00:14:06,793 --> 00:14:08,896 and you could blow up pretty much the entire Earth. 261 00:14:09,000 --> 00:14:13,068 ROWE: Matter has energy because it formed from 262 00:14:13,172 --> 00:14:15,551 energy in the early moments of the universe. 263 00:14:16,724 --> 00:14:19,379 In many ways, atoms are reservoirs 264 00:14:19,482 --> 00:14:22,620 of stored energy from the Big Bang. 265 00:14:22,724 --> 00:14:26,103 ROWE: 13.8 billion years ago, 266 00:14:26,206 --> 00:14:28,586 the universe ignites 267 00:14:28,689 --> 00:14:32,275 in a super hot ball of intense energy. 268 00:14:32,379 --> 00:14:35,137 Right after the Big Bang, there's a tremendous 269 00:14:35,241 --> 00:14:36,620 amount of energy-- so much energy, 270 00:14:36,724 --> 00:14:38,793 in fact, that normal atoms can't exist. 271 00:14:41,275 --> 00:14:44,275 As that early energy starts to cool, 272 00:14:44,379 --> 00:14:47,137 it can start to form primitive matter. 273 00:14:49,793 --> 00:14:52,931 ROWE: The universe takes that first matter and energy 274 00:14:53,034 --> 00:14:55,275 in the form of hydrogen atoms 275 00:14:55,379 --> 00:14:57,655 and starts the process of creating 276 00:14:57,758 --> 00:15:00,068 a supermassive black hole. 277 00:15:00,172 --> 00:15:03,517 Step one-- build giant stars. 278 00:15:03,620 --> 00:15:08,275 So gravity brings together gas, dust, hydrogen, 279 00:15:08,379 --> 00:15:09,379 all of that stuff, 280 00:15:09,482 --> 00:15:11,620 and as the clouds become more dense, 281 00:15:11,724 --> 00:15:14,413 they attract even more material. 282 00:15:14,517 --> 00:15:18,344 NANCE: As they spin, they get hotter and hotter, and as that 283 00:15:18,448 --> 00:15:20,310 temperature and pressure increase, 284 00:15:20,413 --> 00:15:23,724 finally, it ignites nuclear fusion within the core 285 00:15:23,827 --> 00:15:25,586 and creates an actual star. 286 00:15:28,137 --> 00:15:31,827 ROWE: These huge stars are like cosmic rock stars. 287 00:15:31,931 --> 00:15:34,068 They live fast and die young. 288 00:15:35,689 --> 00:15:40,448 When they die, they flame out in a huge explosion, 289 00:15:40,551 --> 00:15:42,379 a supernova. 290 00:15:42,482 --> 00:15:46,758 SUTTER: The entire star turns itself inside out 291 00:15:46,862 --> 00:15:50,068 and releases a shockwave going a good 292 00:15:50,172 --> 00:15:53,965 fraction of the speed of light and releases enough energy to 293 00:15:54,068 --> 00:15:55,965 just obliterate you. 294 00:15:56,068 --> 00:15:59,172 ROWE: If the dying star is more 295 00:15:59,275 --> 00:16:01,482 than 15 stellar masses, 296 00:16:01,586 --> 00:16:04,758 its core collapses into a black hole. 297 00:16:04,862 --> 00:16:08,000 It's kind of astounding what the universe is doing. 298 00:16:08,103 --> 00:16:11,034 It's taking incredibly simple things, like hydrogen atoms, 299 00:16:11,137 --> 00:16:13,551 and using gravity to ultimately 300 00:16:13,655 --> 00:16:15,310 bring all this stuff together and make things 301 00:16:15,413 --> 00:16:17,482 like black holes. 302 00:16:17,586 --> 00:16:20,724 I find it quite beautiful how our whole 303 00:16:20,827 --> 00:16:23,310 cosmic history is the story of 304 00:16:23,413 --> 00:16:26,517 little things coming together into bigger things. 305 00:16:26,620 --> 00:16:29,379 ROWE: But these stellar mass black holes are tiny 306 00:16:29,482 --> 00:16:32,965 flyweights-- to step up to the heavyweight division, 307 00:16:33,068 --> 00:16:36,862 they have to grow billions of times more massive. 308 00:16:36,965 --> 00:16:38,827 But how? 309 00:16:38,931 --> 00:16:41,586 How do black holes become supermassive? 310 00:16:42,758 --> 00:16:44,965 This is the age-old question. 311 00:16:45,068 --> 00:16:46,724 We're not really sure. 312 00:16:46,827 --> 00:16:49,620 TEGMARK: The current state of our understanding 313 00:16:49,724 --> 00:16:52,620 of how black holes become supermassive is like, 314 00:16:52,724 --> 00:16:54,344 uhhh, we're confused. 315 00:16:54,448 --> 00:16:55,793 We really don't know. 316 00:16:55,896 --> 00:16:59,241 We still don't know exactly how they become so big. 317 00:17:01,344 --> 00:17:02,586 ROWE: But we do know that 318 00:17:02,689 --> 00:17:05,413 the process involves ultraviolence, 319 00:17:05,517 --> 00:17:07,206 death, and destruction. 320 00:17:17,965 --> 00:17:22,068 ROWE: How do supermassive black holes grow so big? 321 00:17:22,172 --> 00:17:25,931 That's a question that continues to baffle scientists. 322 00:17:26,034 --> 00:17:30,034 In June of 2018, we spotted a clue, 323 00:17:30,137 --> 00:17:32,310 an enormous flash of light. 324 00:17:32,413 --> 00:17:35,758 AT2018cow, 325 00:17:35,862 --> 00:17:37,103 nicknamed "the cow," 326 00:17:37,206 --> 00:17:40,655 was the brightest explosion ever recorded. 327 00:17:40,758 --> 00:17:42,862 A huge amount of energy was released, 328 00:17:42,965 --> 00:17:44,724 and then all of a sudden, everything was gone. 329 00:17:46,000 --> 00:17:48,862 This explosion was incredibly violent. 330 00:17:48,965 --> 00:17:49,862 At first, it was thought 331 00:17:49,965 --> 00:17:52,137 to just be a supernova, a flash of light. 332 00:17:52,241 --> 00:17:53,724 But over time, it became clear 333 00:17:53,827 --> 00:17:56,103 that this was something much more powerful. 334 00:17:56,206 --> 00:17:59,413 It was too bright, basically, to be a supernova. 335 00:17:59,517 --> 00:18:02,862 It was extremely bright, and it didn't fit into 336 00:18:02,965 --> 00:18:05,034 any of our theoretical understandings 337 00:18:05,137 --> 00:18:07,275 of how bright supernova should be. 338 00:18:08,379 --> 00:18:11,275 ROWE: One explanation is that the light may have come from 339 00:18:11,379 --> 00:18:13,068 a black hole feeding 340 00:18:13,172 --> 00:18:17,482 on a small white dwarf star weighing less than the sun. 341 00:18:17,586 --> 00:18:21,793 What really seemed to fit that model was a star getting 342 00:18:21,896 --> 00:18:23,068 too close to a black hole 343 00:18:23,172 --> 00:18:24,448 and getting ripped apart, and then 344 00:18:24,551 --> 00:18:26,241 everything going right down the black hole. 345 00:18:27,965 --> 00:18:31,103 PLAIT: A black hole gains mass every time it eats something. 346 00:18:31,206 --> 00:18:32,379 That's how they grow. 347 00:18:32,482 --> 00:18:35,275 Whether it's a gas cloud or a star or another black hole, 348 00:18:35,379 --> 00:18:38,517 once it gains that mass, it's gained that mass. 349 00:18:41,137 --> 00:18:42,965 OLUSEYI: People often ask me, what happens to 350 00:18:43,068 --> 00:18:44,793 the mass that falls into a black hole? 351 00:18:44,896 --> 00:18:46,413 Does it go to another dimension? 352 00:18:46,517 --> 00:18:48,965 And the answer is no, it's still there. 353 00:18:49,068 --> 00:18:53,724 It's inside the black hole-- they get bigger, they grow. 354 00:18:53,827 --> 00:18:57,344 ROWE: Could this be how weak flyweight black holes 355 00:18:57,448 --> 00:18:59,379 turn into mean and powerful 356 00:18:59,482 --> 00:19:01,344 supermassive heavyweights? 357 00:19:01,448 --> 00:19:03,344 The star is like protein, 358 00:19:03,448 --> 00:19:07,896 and the black hole is like a boxer. 359 00:19:08,000 --> 00:19:10,724 And so the more protein they get, the more stars 360 00:19:10,827 --> 00:19:12,310 they consume, the stronger they get, 361 00:19:12,413 --> 00:19:13,965 the more destructive they can be. 362 00:19:17,482 --> 00:19:18,931 ROWE: But there's a problem with 363 00:19:19,034 --> 00:19:20,586 the training program explanation. 364 00:19:22,172 --> 00:19:24,206 Eating small stars 365 00:19:24,310 --> 00:19:27,896 one at a time just doesn't add enough mass fast enough 366 00:19:28,000 --> 00:19:29,965 to grow the supermassive black holes 367 00:19:30,068 --> 00:19:31,344 that we see today. 368 00:19:31,448 --> 00:19:36,241 That's like boxers eating just one egg per day. 369 00:19:36,344 --> 00:19:41,344 Like them, black holes need much bigger meals, 370 00:19:41,448 --> 00:19:45,344 and in 2020, we detected one, 371 00:19:45,448 --> 00:19:48,482 a sudden burst of gravitational waves from 372 00:19:48,586 --> 00:19:50,448 a black hole gorging on 373 00:19:50,551 --> 00:19:52,862 the remains of a dead star 374 00:19:52,965 --> 00:19:56,862 called a neutron star. 375 00:19:57,965 --> 00:20:02,137 For scientists, January 2020 was exciting, because it was 376 00:20:02,241 --> 00:20:06,137 the first time LIGO observed the very first black hole 377 00:20:06,241 --> 00:20:07,965 neutron star merger. 378 00:20:08,068 --> 00:20:10,827 ROWE: Neutron stars may be small, 379 00:20:10,931 --> 00:20:14,206 but they are inconceivably dense. 380 00:20:14,310 --> 00:20:16,000 Now, you want to talk about an enormous amount of mass, 381 00:20:16,103 --> 00:20:17,206 let's talk about a neutron star. 382 00:20:17,310 --> 00:20:18,896 That's-- that's one heck of a snack. 383 00:20:20,034 --> 00:20:24,000 ROWE: The black hole swallowed the neutron star in one gulp. 384 00:20:25,310 --> 00:20:29,137 So this black hole ate a whole neutron star, 385 00:20:29,241 --> 00:20:32,586 which means it gained just over 10 percent of its entire 386 00:20:32,689 --> 00:20:35,103 body weight in one shot. 387 00:20:35,206 --> 00:20:37,793 ROWE: 10 percent doesn't sound like a lot, 388 00:20:37,896 --> 00:20:39,862 but then we detected another 389 00:20:39,965 --> 00:20:43,896 black hole swallowing a neutron star just 10 days later, 390 00:20:44,000 --> 00:20:47,827 suggesting that there are lots of black holes bulking up 391 00:20:47,931 --> 00:20:49,000 across the universe. 392 00:20:49,103 --> 00:20:52,172 But even with this extreme weight gain, 393 00:20:52,275 --> 00:20:56,068 it's probably not enough to get supermassive. 394 00:20:56,172 --> 00:20:58,000 They need to eat even more. 395 00:20:59,275 --> 00:21:01,448 If you're a black hole, and you want to get bigger, 396 00:21:01,551 --> 00:21:05,000 your best bet is to merge with another black hole. 397 00:21:05,103 --> 00:21:07,206 ROWE: But there's a catch. 398 00:21:07,310 --> 00:21:13,241 So if you're a flyweight black hole, and you try to eat all of 399 00:21:13,344 --> 00:21:15,310 the other flyweight black holes, 400 00:21:15,413 --> 00:21:18,793 there's just not enough time in the history of the universe 401 00:21:18,896 --> 00:21:21,551 for you to become a supermassive black hole. 402 00:21:21,655 --> 00:21:24,000 But you can make it to middleweight. 403 00:21:24,103 --> 00:21:28,137 ROWE: So exactly how supermassive black holes 404 00:21:28,241 --> 00:21:31,620 grow so large remains an open question. 405 00:21:31,724 --> 00:21:35,103 We do know that the process started in the very early 406 00:21:35,206 --> 00:21:36,827 universe with a journey 407 00:21:36,931 --> 00:21:38,896 from the lightest element to the most 408 00:21:39,000 --> 00:21:42,103 intimidating object in the cosmos. 409 00:21:42,206 --> 00:21:44,896 It's so interesting how the cosmos can take something as 410 00:21:45,000 --> 00:21:48,586 simple as a hydrogen atom and build stellar mass 411 00:21:48,689 --> 00:21:52,448 black holes and intermediate mass black holes 412 00:21:52,551 --> 00:21:54,862 and even supermassive black holes out of 413 00:21:54,965 --> 00:21:59,137 these really densely compressed hydrogen atoms. 414 00:21:59,241 --> 00:22:01,896 It's really a wonder. 415 00:22:02,000 --> 00:22:04,896 ROWE: Now, 13.8 billion years 416 00:22:05,000 --> 00:22:08,068 after the Big Bang, supermassive black holes 417 00:22:08,172 --> 00:22:10,551 feed and flex their muscles, 418 00:22:10,655 --> 00:22:12,482 ready to fight for the heavyweight 419 00:22:12,586 --> 00:22:14,379 championship of the universe. 420 00:22:14,482 --> 00:22:17,655 These supermassive black holes have been bulking up 421 00:22:17,758 --> 00:22:19,517 since the age of the universe. 422 00:22:19,620 --> 00:22:21,551 SUTTER: These black holes have been 423 00:22:21,655 --> 00:22:23,413 getting ready for the fight. 424 00:22:23,517 --> 00:22:24,931 They have been bulking up. 425 00:22:25,034 --> 00:22:28,655 They have been eating entire stars as snacks 426 00:22:28,758 --> 00:22:30,793 to get the masks they need. 427 00:22:30,896 --> 00:22:32,689 So they are ready to rumble. 428 00:22:33,793 --> 00:22:36,000 ROWE: It's not the rumble in the jungle. 429 00:22:36,103 --> 00:22:40,000 This is the battle to be the boss of the cosmos. 430 00:22:40,103 --> 00:22:44,137 Supermassive black hole versus supermassive 431 00:22:44,241 --> 00:22:48,275 black hole, fought in the grandest arena. 432 00:22:48,379 --> 00:22:52,310 The fighter's entourage, their host galaxies, 433 00:22:52,413 --> 00:22:54,275 escort them to the ring. 434 00:22:54,379 --> 00:22:56,551 But even this journey is violent, 435 00:22:56,655 --> 00:23:00,551 triggering starbursts, jets, and carnage. 436 00:23:11,379 --> 00:23:14,034 ROWE: It's the build up before the heavyweight fight 437 00:23:14,137 --> 00:23:15,758 of the cosmos. 438 00:23:15,862 --> 00:23:19,517 The fighters' entourages, their galaxies, carry 439 00:23:19,620 --> 00:23:22,034 their supermassive black holes to the ring. 440 00:23:23,344 --> 00:23:25,241 Things are about to get nasty. 441 00:23:26,448 --> 00:23:28,862 Galaxies can look calm and serene, 442 00:23:28,965 --> 00:23:31,310 but they can get into pretty big scraps. 443 00:23:33,862 --> 00:23:35,724 There's a lot of them that are totally 444 00:23:35,827 --> 00:23:39,448 messed up and are clearly merging with each other. 445 00:23:42,655 --> 00:23:46,275 ROWE: When galaxies fight, their gravity pulls on each 446 00:23:46,379 --> 00:23:49,310 other, twisting and distorting their structures. 447 00:23:49,413 --> 00:23:54,586 The galaxy will be warped and morphed into different ways 448 00:23:54,689 --> 00:23:58,206 that we can only imagine how twisted it would be. 449 00:24:00,000 --> 00:24:02,034 ROWE: This violent cosmic tango brings 450 00:24:02,137 --> 00:24:04,965 the two supermassive black holes together. 451 00:24:05,068 --> 00:24:07,655 TREMBLAY: It's elegant, it's beautiful. 452 00:24:07,758 --> 00:24:12,206 It's this billion-year choreographed dance 453 00:24:12,310 --> 00:24:14,862 that is entirely conducted by gravity. 454 00:24:18,448 --> 00:24:21,482 ROWE: The two heavyweight fighters approach each other. 455 00:24:21,586 --> 00:24:23,620 Their feet beat out a rhythm on the canvas, 456 00:24:23,724 --> 00:24:27,965 just like circling black holes release low energy 457 00:24:28,068 --> 00:24:29,517 gravitational waves. 458 00:24:30,689 --> 00:24:34,758 You have these giant beasts that are stalking 459 00:24:34,862 --> 00:24:36,827 around each other, and as they do, 460 00:24:36,931 --> 00:24:39,655 they create these gravitational waves. 461 00:24:41,965 --> 00:24:44,655 ROWE: June 2021. 462 00:24:44,758 --> 00:24:47,620 Astronomers photograph a galactic collision 463 00:24:47,724 --> 00:24:51,931 and witness a spectacular pre-fight fireworks show. 464 00:24:52,034 --> 00:24:54,862 One of the amazing things that can happen 465 00:24:54,965 --> 00:24:56,724 when galaxies collide is they can create 466 00:24:56,827 --> 00:24:58,896 tremendous starbursts. 467 00:24:59,000 --> 00:25:01,689 There is a big inrush as all of 468 00:25:01,793 --> 00:25:05,586 the gas follows that gravity-- as the gas gets hotter 469 00:25:05,689 --> 00:25:08,758 and denser, it creates shockwaves, 470 00:25:08,862 --> 00:25:11,448 and each shockwave actually creates a new generation of 471 00:25:11,551 --> 00:25:14,793 stars going out around the core of the galaxy. 472 00:25:14,896 --> 00:25:18,620 ROWE: The sudden starburst lights up the merging galaxies. 473 00:25:18,724 --> 00:25:22,000 The inrushing gas also fuels the prize fighters, 474 00:25:23,068 --> 00:25:25,689 the supermassive black holes spiraling 475 00:25:25,793 --> 00:25:29,965 towards the merging galactic center. 476 00:25:30,068 --> 00:25:33,551 PONTZEN: If there's a big supermassive black hole, 477 00:25:33,655 --> 00:25:37,000 it suddenly finds it surrounded by loads of gas 478 00:25:37,103 --> 00:25:39,827 and other material it can eat. 479 00:25:39,931 --> 00:25:42,620 It goes on a kind of feeding frenzy. 480 00:25:42,724 --> 00:25:45,034 If you're a hungry supermassive black hole, 481 00:25:45,137 --> 00:25:48,241 then this is your lunchtime buffet. 482 00:25:48,344 --> 00:25:52,241 ROWE: Not all the gas falls into the supermassive black hole. 483 00:25:52,344 --> 00:25:56,448 Other parts of the matter actually gets caught up 484 00:25:56,551 --> 00:25:58,379 in what we call an accretion disk 485 00:25:58,482 --> 00:26:01,965 rotating around the outside of the black hole. 486 00:26:02,068 --> 00:26:05,068 ROWE: This bright vortex spins around the supermassive 487 00:26:05,172 --> 00:26:09,068 black hole at over two million miles an hour. 488 00:26:09,172 --> 00:26:12,413 The material in the disk rubs against itself, 489 00:26:12,517 --> 00:26:14,551 creating friction. 490 00:26:14,655 --> 00:26:18,413 Friction generates heat-- if I rub my hands together, 491 00:26:18,517 --> 00:26:20,000 they get a little bit warm. 492 00:26:20,103 --> 00:26:24,068 If I rub my hands together at hundreds of thousands of 493 00:26:24,172 --> 00:26:27,241 miles per hour, it's gonna get very, very, very warm. 494 00:26:29,655 --> 00:26:31,551 ROWE: The accretion disk heats up, 495 00:26:31,655 --> 00:26:34,000 blasting out intense light. 496 00:26:35,931 --> 00:26:36,965 In 2020, 497 00:26:37,068 --> 00:26:40,689 NASA's Hubble space telescope saw two fueled-up 498 00:26:40,793 --> 00:26:44,034 supermassive black holes lighting up for the fight. 499 00:26:45,827 --> 00:26:47,620 We call them quasars. 500 00:26:49,344 --> 00:26:54,551 Quasars are a subclass of very bright black holes 501 00:26:54,655 --> 00:26:56,827 that are emitting huge amounts of power. 502 00:26:56,931 --> 00:26:59,931 So these can be seen at the far reaches of the universe. 503 00:27:02,724 --> 00:27:05,241 TREMBLAY: Black holes, these so-called dark things, 504 00:27:05,344 --> 00:27:07,482 when they're growing at a very high rate 505 00:27:07,586 --> 00:27:10,379 are some of the brightest lights in the universe. 506 00:27:11,482 --> 00:27:14,655 ROWE: To date, we've detected over 100 pairs 507 00:27:14,758 --> 00:27:18,689 of quasars in the cores of merging galaxies. 508 00:27:18,793 --> 00:27:22,896 We think they will all eventually collide, 509 00:27:23,000 --> 00:27:26,931 but before they do, they'll put on a spectacular 510 00:27:27,034 --> 00:27:29,793 and lethal light show. 511 00:27:29,896 --> 00:27:33,241 A common theme in science fiction 512 00:27:33,344 --> 00:27:35,689 are different kind of jets of energy or beams 513 00:27:35,793 --> 00:27:38,068 that people shoot out of their eyes or their hands. 514 00:27:38,172 --> 00:27:41,482 Well, supermassive black holes do that, too. 515 00:27:41,586 --> 00:27:44,103 ROWE: Firing out relativistic jets. 516 00:27:45,482 --> 00:27:49,034 When those jets fire up, 517 00:27:49,137 --> 00:27:52,172 that's when you're talking about superstar, really, 518 00:27:52,275 --> 00:27:55,275 really bright lights, and at this point, the galaxy is lit up 519 00:27:55,379 --> 00:27:56,413 and ready to go. 520 00:27:58,344 --> 00:28:02,586 These are the spotlight's on Madison Square Garden. 521 00:28:02,689 --> 00:28:05,724 This is telling you that the event is going down. 522 00:28:05,827 --> 00:28:07,517 [crowd cheering] 523 00:28:07,620 --> 00:28:10,034 A single supermassive black hole jet 524 00:28:10,137 --> 00:28:13,000 will produce more energy in a second 525 00:28:13,103 --> 00:28:14,655 than the sun will produce in 526 00:28:14,758 --> 00:28:17,137 its entire 10-billion-year lifetime. 527 00:28:22,137 --> 00:28:25,586 Imagine a laser of radiation that 528 00:28:25,689 --> 00:28:27,827 is light-years in length and across. 529 00:28:27,931 --> 00:28:29,241 That's what we're talking about. 530 00:28:29,344 --> 00:28:31,827 This thing would fry a planet. 531 00:28:32,965 --> 00:28:35,689 ROWE: This is no pre-fight hype. 532 00:28:35,793 --> 00:28:40,344 In February 2020, we saw the impact of a jet. 533 00:28:41,689 --> 00:28:43,551 TREMBLAY: So in the Ophiuchus galaxy cluster, 534 00:28:43,655 --> 00:28:46,758 there's an enormous void that is 15 times wider than 535 00:28:46,862 --> 00:28:47,862 the Milky Way galaxy. 536 00:28:47,965 --> 00:28:50,068 And this has all been sculpted, carved, 537 00:28:50,172 --> 00:28:53,931 by jets from a supermassive black hole. 538 00:28:54,034 --> 00:28:55,931 STRAUGHN: It's like this scar on the universe. 539 00:28:56,034 --> 00:28:57,793 It's a million light-years across. 540 00:28:57,896 --> 00:28:59,965 It's huge. 541 00:29:00,068 --> 00:29:03,034 ROWE: Scientists calculate the impact of the jet hitting 542 00:29:03,137 --> 00:29:05,379 the cluster was equivalent to 543 00:29:05,482 --> 00:29:10,689 a 20-billion-billion megaton TNT explosion every 1,000th of 544 00:29:10,793 --> 00:29:14,586 a second for 240 million years. 545 00:29:18,103 --> 00:29:20,896 The relativistic jets' immense power may be 546 00:29:21,000 --> 00:29:21,931 a showstopper. 547 00:29:22,034 --> 00:29:24,448 But when it's time to land the killer punch, 548 00:29:24,551 --> 00:29:29,448 supermassive black holes draw on an even more powerful force, 549 00:29:29,551 --> 00:29:31,068 gravity. 550 00:29:31,172 --> 00:29:33,241 STRAUGHN: Jets are very powerful, but really 551 00:29:33,344 --> 00:29:35,310 only on a relatively small scale. 552 00:29:35,413 --> 00:29:37,758 When you're talking about cosmic scale, 553 00:29:37,862 --> 00:29:39,413 gravity always wins. 554 00:29:39,517 --> 00:29:42,275 Nothing is as powerful as gravity. 555 00:29:42,379 --> 00:29:44,034 ROWE: The immense gravity of the circling 556 00:29:44,137 --> 00:29:48,172 supermassive black holes drags them ever closer, 557 00:29:48,275 --> 00:29:51,586 but will it ultimately bring them together 558 00:29:51,689 --> 00:29:53,448 or blast them apart? 559 00:30:03,965 --> 00:30:05,965 ROWE: Across the universe, 560 00:30:06,068 --> 00:30:09,413 supermassive black holes duke it out 561 00:30:09,517 --> 00:30:14,000 in the cosmos's version of heavyweight super fights. 562 00:30:14,103 --> 00:30:18,827 Supermassive black holes are merging around us all the time. 563 00:30:18,931 --> 00:30:21,310 It's only our ability to detect them 564 00:30:21,413 --> 00:30:23,241 that's preventing us from seeing them. 565 00:30:25,586 --> 00:30:28,103 ROWE: Scientists have identified at least a dozen 566 00:30:28,206 --> 00:30:31,965 pairs of supermassive black holes circling each other. 567 00:30:33,344 --> 00:30:35,655 We have some hints of some galaxies 568 00:30:35,758 --> 00:30:37,068 where we think it might happen, 569 00:30:37,172 --> 00:30:39,931 where we see two glowing black holes that are getting 570 00:30:40,034 --> 00:30:40,965 very close. 571 00:30:42,344 --> 00:30:44,965 ROWE: But not all these matches will end with a knockout. 572 00:30:46,241 --> 00:30:48,793 Black hole collisions happen all the time. 573 00:30:48,896 --> 00:30:51,482 But they don't always go according to plan. 574 00:30:51,586 --> 00:30:53,172 When black holes come together, 575 00:30:53,275 --> 00:30:55,620 really strange things can happen. 576 00:30:57,068 --> 00:31:01,344 ROWE: The Hubble space telescope spots something strange in 577 00:31:01,448 --> 00:31:06,068 a distant galaxy called 3C186. 578 00:31:06,172 --> 00:31:10,000 It's a quasar, an active supermassive black hole. 579 00:31:12,482 --> 00:31:13,724 But it's in the wrong place. 580 00:31:15,103 --> 00:31:18,413 In nearly every galaxy we see, the supermassive black hole 581 00:31:18,517 --> 00:31:20,310 sits right at the center, and that makes sense. 582 00:31:21,482 --> 00:31:22,586 SUTTER: Because that's the only place 583 00:31:22,689 --> 00:31:25,551 with enough material to power them. 584 00:31:25,655 --> 00:31:28,965 But in 3C186, that's not what we see. 585 00:31:29,068 --> 00:31:31,379 The supermassive black hole is displaced from 586 00:31:31,482 --> 00:31:33,034 the center, and not a little bit. 587 00:31:33,137 --> 00:31:35,310 It's 35,000 light-years. 588 00:31:35,413 --> 00:31:38,275 So to see a quasar 35,000 light-years away from 589 00:31:38,379 --> 00:31:41,000 the core means something really violent 590 00:31:41,103 --> 00:31:42,241 had to happen there. 591 00:31:42,344 --> 00:31:45,275 ROWE: The quasar is racing away from the center 592 00:31:45,379 --> 00:31:49,172 of the galaxy at over four million miles an hour. 593 00:31:49,275 --> 00:31:51,586 OLUSEYI: That is insane. 594 00:31:51,689 --> 00:31:53,448 The magnitude of the energy 595 00:31:53,551 --> 00:31:57,655 and the forces required are just something unimaginable. 596 00:31:57,758 --> 00:32:02,931 So what can kick a giant black hole out of a galaxy? 597 00:32:03,034 --> 00:32:06,172 What has that kind of power? 598 00:32:06,275 --> 00:32:11,103 ROWE: The answer is a clash that wasn't evenly matched. 599 00:32:11,206 --> 00:32:15,379 The two supermassive black holes were different sizes-- 600 00:32:15,482 --> 00:32:19,068 a middleweight boxer taking on a heavyweight. 601 00:32:20,482 --> 00:32:23,172 When we humans set up a fight, we like to make it fair, 602 00:32:23,275 --> 00:32:24,448 because it's sport. 603 00:32:24,551 --> 00:32:25,896 Nature doesn't care about sport. 604 00:32:26,000 --> 00:32:27,379 It's survival of the fittest. 605 00:32:27,482 --> 00:32:28,896 This is not a fair fight. 606 00:32:29,000 --> 00:32:31,862 It's over before it even begins. 607 00:32:31,965 --> 00:32:34,137 One punch, and it's a K.O. 608 00:32:36,862 --> 00:32:39,034 As these two black holes are merging, 609 00:32:39,137 --> 00:32:41,172 there's one really small black hole 610 00:32:41,275 --> 00:32:42,620 and one much bigger black hole. 611 00:32:42,724 --> 00:32:45,517 The whole system wobbles around, and it can get more of 612 00:32:45,620 --> 00:32:47,379 a gravitational wave kick in one 613 00:32:47,482 --> 00:32:50,103 - direction than the other. - And that's momentum. 614 00:32:50,206 --> 00:32:53,448 That's a push, that's enough energy to kick 615 00:32:53,551 --> 00:32:54,862 the black hole out. 616 00:32:56,896 --> 00:32:59,103 ROWE: The lopsided gravitational punch 617 00:32:59,206 --> 00:33:01,275 sends the merged supermassive 618 00:33:01,379 --> 00:33:04,068 black hole on a one-way trip to oblivion. 619 00:33:05,896 --> 00:33:07,413 This tells us that gravitational 620 00:33:07,517 --> 00:33:10,068 waves can be tremendously powerful. 621 00:33:10,172 --> 00:33:12,965 They can move a supermassive black hole out from 622 00:33:13,068 --> 00:33:16,275 the center of a galaxy and send it on its way. 623 00:33:16,379 --> 00:33:17,793 PONTZEN: But it just carries on drifting. 624 00:33:17,896 --> 00:33:19,931 There's no way to stop it. 625 00:33:20,034 --> 00:33:21,862 And who knows, in a few million years it could 626 00:33:21,965 --> 00:33:24,655 just drift entirely out of its galaxy 627 00:33:24,758 --> 00:33:27,206 and go floating off into deep space. 628 00:33:29,586 --> 00:33:31,482 ROWE: In some matches, the fighters 629 00:33:31,586 --> 00:33:33,137 don't even land a punch. 630 00:33:35,172 --> 00:33:38,206 Scientists spot a supermassive black hole 631 00:33:38,310 --> 00:33:42,965 named B3 1715 425. 632 00:33:44,275 --> 00:33:46,344 This black hole is strange. 633 00:33:47,931 --> 00:33:49,620 Stripped of all its stars, 634 00:33:49,724 --> 00:33:54,137 it hurtles through empty space at 4.5 million miles an hour. 635 00:33:54,241 --> 00:33:56,275 The first thing that draws our attention is 636 00:33:56,379 --> 00:34:00,448 this faint trail of debris across the sky. 637 00:34:00,551 --> 00:34:02,689 PLAIT: There is actually a trail leading 638 00:34:02,793 --> 00:34:04,482 back to the center of the galaxy. 639 00:34:04,586 --> 00:34:07,103 It's kind of like a dump truck, right, that's filled with 640 00:34:07,206 --> 00:34:09,482 dirt driving down the highway, and the dirt's flying off 641 00:34:09,586 --> 00:34:12,620 behind it-- this is a naked black hole. 642 00:34:12,724 --> 00:34:14,896 ROWE: The exposed super massive black hole 643 00:34:15,000 --> 00:34:17,206 has lost its stars and galaxy, 644 00:34:17,310 --> 00:34:21,862 a champion stripped of its fans and entourage. 645 00:34:21,965 --> 00:34:25,172 So what event is powerful enough to strip 646 00:34:25,275 --> 00:34:29,862 a supermassive black hole of its entire host galaxy? 647 00:34:29,965 --> 00:34:31,793 That has to be something really big. 648 00:34:34,379 --> 00:34:36,413 PLAIT: B3 is a smallish galaxy, and it 649 00:34:36,517 --> 00:34:38,620 got into a scrap with a much bigger one. 650 00:34:38,724 --> 00:34:40,655 The stronger gravity of the bigger galaxy 651 00:34:40,758 --> 00:34:43,689 stripped the stars away from that black hole and shot it out. 652 00:34:45,965 --> 00:34:47,551 Typically in the universe, when something 653 00:34:47,655 --> 00:34:49,448 is bigger and more massive, it wins. 654 00:34:49,551 --> 00:34:51,206 So this is true for galaxies. 655 00:34:51,310 --> 00:34:54,000 A big galaxy versus a little galaxy-- 656 00:34:54,103 --> 00:34:55,310 put your money on the big one. 657 00:34:56,965 --> 00:34:59,586 ROWE: But when two evenly matched heavyweights 658 00:34:59,689 --> 00:35:00,655 enter the ring, 659 00:35:02,206 --> 00:35:04,724 it's time for the main event. 660 00:35:04,827 --> 00:35:06,310 [crowd chanting] 661 00:35:06,413 --> 00:35:08,896 A clash of the titans. 662 00:35:09,000 --> 00:35:11,482 I grew up watching boxing with my dad. 663 00:35:11,586 --> 00:35:15,379 So I've always been a boxing fan, and I love a great battle. 664 00:35:15,482 --> 00:35:17,586 And what's a bigger battle than 665 00:35:17,689 --> 00:35:21,655 a head-on collision between two supermassive black holes? 666 00:35:21,758 --> 00:35:25,034 If you're a boxing fan, this is the big one. 667 00:35:25,137 --> 00:35:26,275 SUTTER: We are ready. 668 00:35:26,379 --> 00:35:28,896 We are on the edge of our seats. 669 00:35:29,000 --> 00:35:31,551 MINGARELLI: We've got two supermassive black holes, 670 00:35:31,655 --> 00:35:34,344 each one is in their corner, and they're getting ready for 671 00:35:34,448 --> 00:35:35,689 the fight of the century. 672 00:35:38,103 --> 00:35:40,896 I mean, they're just gonna go at it like goosh, goosh. 673 00:35:41,000 --> 00:35:43,793 I would watch that. I'd Pay-Per-View that. 674 00:35:43,896 --> 00:35:45,172 OLUSEYI: It doesn't get any better than this. 675 00:35:45,275 --> 00:35:48,275 These are prize fighters at the top of their game. 676 00:35:48,379 --> 00:35:49,862 They're trained to a T. 677 00:35:49,965 --> 00:35:51,241 They're beefed up. 678 00:35:51,344 --> 00:35:53,758 They are ready to rumble. 679 00:35:53,862 --> 00:35:58,275 ROWE: We are just seconds away from the fight of the cosmos. 680 00:36:12,103 --> 00:36:14,344 ROWE: Welcome to the heavyweight championship 681 00:36:14,448 --> 00:36:15,758 of the universe. 682 00:36:15,862 --> 00:36:19,068 Weighing in at eight billion solar masses, 683 00:36:19,172 --> 00:36:24,517 We have the galactic destroyer, M101 star. 684 00:36:24,620 --> 00:36:26,172 And in the other corner, 685 00:36:26,275 --> 00:36:29,793 at a punishing 7.8 billion suns, 686 00:36:29,896 --> 00:36:34,103 the star crusher, NSC47 star. 687 00:36:34,206 --> 00:36:37,310 They are pumped and ready to rumble. 688 00:36:37,413 --> 00:36:40,551 So here it is, we're finally here. 689 00:36:40,655 --> 00:36:43,241 The crowd is roaring. 690 00:36:43,344 --> 00:36:44,793 The bell has rung, 691 00:36:44,896 --> 00:36:47,000 and the fighters are approaching each other. 692 00:36:47,103 --> 00:36:49,068 They are ready to go at it. 693 00:36:51,206 --> 00:36:52,896 ROWE: Let's have a clean fight, fellas. 694 00:36:53,000 --> 00:36:55,482 Touch hands, and go back to your corners. 695 00:36:57,241 --> 00:37:00,241 Round one. The two heavyweights circle, 696 00:37:00,344 --> 00:37:02,689 testing the other's defenses. 697 00:37:02,793 --> 00:37:04,965 The black hole's gonna do what the boxes are gonna do. 698 00:37:05,068 --> 00:37:06,724 They're gonna circle each other, 699 00:37:06,827 --> 00:37:08,206 and they're gonna orbit each other, 700 00:37:08,310 --> 00:37:10,000 and they're gonna size each other up. 701 00:37:11,862 --> 00:37:13,965 PLAIT: Once these two supermassive black holes 702 00:37:14,068 --> 00:37:15,827 are close enough, their gravity, 703 00:37:15,931 --> 00:37:18,000 inexorably, is gonna draw them together. 704 00:37:20,758 --> 00:37:23,689 ROWE: As the two supermassive black holes get closer, 705 00:37:23,793 --> 00:37:26,344 they throw a few exploratory jabs, 706 00:37:30,068 --> 00:37:32,862 triggering bursts of gravitational waves 707 00:37:32,965 --> 00:37:34,827 that warp everything in their path. 708 00:37:36,310 --> 00:37:39,517 These enormous gravitational waves are completely 709 00:37:39,620 --> 00:37:42,827 deforming the fabric of spacetime around them. 710 00:37:42,931 --> 00:37:44,965 Not just a little bit, but a lot. 711 00:37:45,068 --> 00:37:48,413 It's like feeling the fighters approach in 712 00:37:48,517 --> 00:37:50,689 the boxing ring... 713 00:37:50,793 --> 00:37:53,482 from the next town over. 714 00:37:57,793 --> 00:38:01,517 ROWE: Next, the supermassive black hole's gravity throws in 715 00:38:01,620 --> 00:38:03,172 a couple of right hooks 716 00:38:03,275 --> 00:38:05,517 straight into the accretion disks. 717 00:38:09,068 --> 00:38:11,551 MINGARELLI: What could happen is that they start to form 718 00:38:11,655 --> 00:38:12,827 like an angle grinder. 719 00:38:12,931 --> 00:38:16,275 You'll see sparks flying as they try to merge and form 720 00:38:16,379 --> 00:38:18,172 a new single accretion disk. 721 00:38:18,275 --> 00:38:20,620 When those accretion disks collide, 722 00:38:20,724 --> 00:38:25,310 the whole thing is gonna light up like the Fourth of July. 723 00:38:25,413 --> 00:38:29,000 ROWE: Spiraling in at millions of miles an hour, 724 00:38:29,103 --> 00:38:31,137 the heavyweight fighters get close, 725 00:38:31,241 --> 00:38:33,413 delivering punishing body blows. 726 00:38:37,896 --> 00:38:40,137 The event horizons, the surface of 727 00:38:40,241 --> 00:38:43,379 the supermassive black holes, are about to touch. 728 00:38:45,275 --> 00:38:46,586 In their final moments, 729 00:38:46,689 --> 00:38:49,482 these two supermassive black holes are orbiting each other 730 00:38:49,586 --> 00:38:51,413 at a significant fraction 731 00:38:51,517 --> 00:38:53,827 of the speed of light, and their event horizons 732 00:38:53,931 --> 00:38:54,896 will touch. 733 00:38:56,827 --> 00:38:59,103 And they'll eventually merge into one new 734 00:38:59,206 --> 00:39:01,000 supermassive black hole. 735 00:39:01,103 --> 00:39:02,310 TEGMARK: You might think, 736 00:39:02,413 --> 00:39:04,689 don't they bump into each other like bowling balls? 737 00:39:04,793 --> 00:39:05,965 No, they don't. 738 00:39:06,068 --> 00:39:07,931 Because what we're calling the edge of a black hole is 739 00:39:08,034 --> 00:39:10,827 actually not a thing-- that's just 740 00:39:10,931 --> 00:39:12,758 the surface around the black hole. 741 00:39:12,862 --> 00:39:15,655 Gravity is so strong that nothing can come out. 742 00:39:15,758 --> 00:39:19,586 ROWE: The two supermassive black holes finally merge, 743 00:39:19,689 --> 00:39:23,551 releasing around 5 percent of the mass they've gathered over 744 00:39:23,655 --> 00:39:25,620 billions of years in 745 00:39:25,724 --> 00:39:29,965 an enormous burst of gravitational waves. 746 00:39:30,068 --> 00:39:31,931 The amount of energy that we're talking about... 747 00:39:34,137 --> 00:39:36,931 there's nothing to compare it to-- it's mind-crushing. 748 00:39:37,034 --> 00:39:40,172 There's really almost no point in thinking about it. 749 00:39:40,275 --> 00:39:42,551 It's just not something I think that I can 750 00:39:42,655 --> 00:39:43,827 wrap my head around. 751 00:39:43,931 --> 00:39:45,896 Coming from where I come from, 752 00:39:46,000 --> 00:39:47,758 you know, you don't show weakness, 753 00:39:47,862 --> 00:39:50,620 so I'm not gonna say that the collision of two black holes 754 00:39:50,724 --> 00:39:53,379 is more powerful than one of my punches, but... 755 00:39:54,758 --> 00:39:56,000 it's close. 756 00:39:57,482 --> 00:40:01,379 ROWE: The gigantic and powerful gravitational waves race out 757 00:40:01,482 --> 00:40:03,172 from the collision zone, 758 00:40:03,275 --> 00:40:07,034 leaving a single merged black hole. 759 00:40:07,137 --> 00:40:11,344 The supermassive black hole, after it merges, permanently 760 00:40:11,448 --> 00:40:14,965 deforms the fabric of spacetime around it, and this deformation 761 00:40:15,068 --> 00:40:17,068 travels out at the speed of light. 762 00:40:18,793 --> 00:40:22,586 ROWE: The surviving 95 percent of mass from the two colliding 763 00:40:22,689 --> 00:40:24,655 supermassive black holes 764 00:40:24,758 --> 00:40:29,482 is now locked in a single ultramassive black hole, 765 00:40:29,586 --> 00:40:33,137 the undisputed super heavyweight champion of 766 00:40:33,241 --> 00:40:35,758 the universe-- at least for now. 767 00:40:37,137 --> 00:40:39,379 It seems the universe is always upping the ante. 768 00:40:39,482 --> 00:40:41,275 Could there be something even more 769 00:40:41,379 --> 00:40:42,827 violent we haven't even discovered yet? 770 00:40:42,931 --> 00:40:45,482 The universe keeps wanting to give us 771 00:40:45,586 --> 00:40:47,758 something more violent all the time. 772 00:40:47,862 --> 00:40:52,413 ROWE: Energy locked in hydrogen atoms formed at the birth of 773 00:40:52,517 --> 00:40:54,862 the universe is finally 774 00:40:54,965 --> 00:40:58,931 released in the violent collision and builds 775 00:40:59,034 --> 00:41:01,068 an ultramassive black hole. 776 00:41:04,000 --> 00:41:06,827 SUTTER: This is one of the most beautiful stories in 777 00:41:06,931 --> 00:41:09,827 our universe-- you have the most energetic collision, 778 00:41:09,931 --> 00:41:11,620 the most amount of energy released, 779 00:41:11,724 --> 00:41:14,241 the most violent event, can trace 780 00:41:14,344 --> 00:41:17,448 its origins to the humble hydrogen atom. 781 00:41:20,379 --> 00:41:23,724 ROWE: So we have our champion-- matter compressed 782 00:41:23,827 --> 00:41:26,965 and then smashed together by supermassive black holes 783 00:41:27,068 --> 00:41:30,586 creates the most violent event in the universe. 784 00:41:31,862 --> 00:41:33,586 I don't think there's a contest. 785 00:41:33,689 --> 00:41:35,758 The supermassive black hole collisions 786 00:41:35,862 --> 00:41:37,448 are the most energetic, 787 00:41:37,551 --> 00:41:42,034 just, like, mind-numbingly large amounts of energy in 788 00:41:42,137 --> 00:41:43,137 these collisions. 789 00:41:46,034 --> 00:41:48,896 A merger of two supermassive black holes 790 00:41:49,000 --> 00:41:52,206 is at the absolute top end extreme of that 791 00:41:52,310 --> 00:41:56,034 for all possible events in the entire universe, 792 00:41:56,137 --> 00:41:59,000 A supermassive black hole merger is the most 793 00:41:59,103 --> 00:42:02,172 violent thing that we can observe in the universe.