1 00:00:02,602 --> 00:00:04,536 MIKE ROWE: We're on a journey to the heart 2 00:00:04,637 --> 00:00:08,974 of the supermassive black hole, M87 star. 3 00:00:09,075 --> 00:00:13,779 Our mission, to investigate one of the most mysterious places 4 00:00:13,880 --> 00:00:15,180 in the universe. 5 00:00:15,281 --> 00:00:19,551 SUTTER: M87 is a great target for us to visit, 6 00:00:19,652 --> 00:00:24,056 because one, it's close, and two, it's active, 7 00:00:24,157 --> 00:00:26,759 it's feeding. 8 00:00:26,860 --> 00:00:28,761 ROWE: Supermassive black holes are 9 00:00:28,862 --> 00:00:31,997 the engines that power the universe. 10 00:00:32,098 --> 00:00:35,200 Supermassive black holes are a key factor in 11 00:00:35,301 --> 00:00:38,771 the birth, life, and eventual death of galaxies. 12 00:00:40,440 --> 00:00:41,907 ROWE: And the more we study them, 13 00:00:42,008 --> 00:00:43,876 the more puzzling they become. 14 00:00:45,545 --> 00:00:46,645 They're the master key 15 00:00:46,746 --> 00:00:50,416 to most of the unsolved mysteries in physics. 16 00:00:50,517 --> 00:00:53,886 The physics inside a supermassive black hole are 17 00:00:53,987 --> 00:00:55,754 beyond weird. 18 00:00:55,855 --> 00:00:59,758 ROWE: They are the final frontier of our understanding. 19 00:00:59,859 --> 00:01:01,693 Your imagination can run wild. 20 00:01:01,795 --> 00:01:04,063 Maybe it's even the source of other universes. 21 00:01:04,164 --> 00:01:07,099 ROWE: There's only one way to find out, 22 00:01:07,200 --> 00:01:12,871 to go where no one has gone before and journey to the heart 23 00:01:12,972 --> 00:01:15,607 of M87 star. 24 00:01:18,445 --> 00:01:21,146 [explosion blasts] 25 00:01:29,089 --> 00:01:31,590 We speed across M87, 26 00:01:32,792 --> 00:01:37,329 a gigantic galaxy 55 million light-years from Earth. 27 00:01:41,334 --> 00:01:44,269 At its heart lies a supermassive black hole, 28 00:01:45,939 --> 00:01:48,006 M87 star. 29 00:01:49,542 --> 00:01:53,145 It is the first and only black hole 30 00:01:53,246 --> 00:01:55,481 ever photographed. 31 00:01:55,582 --> 00:01:59,985 We want to find out how M87 star grew so large, 32 00:02:00,086 --> 00:02:04,123 what lies inside, and how it controls the galaxy. 33 00:02:08,728 --> 00:02:12,464 5,000 light-years out from the supermassive black hole, 34 00:02:12,565 --> 00:02:16,301 we get our first sign of the danger ahead. 35 00:02:16,402 --> 00:02:19,605 We see giant holes carved out of the galaxy, 36 00:02:21,474 --> 00:02:25,144 starless voids thousands of light-years wide. 37 00:02:26,679 --> 00:02:28,647 SUTTER: As we approach, we can see 38 00:02:28,748 --> 00:02:31,750 that wreckage littered around the vicinity. 39 00:02:31,851 --> 00:02:34,853 It's like entering the lair of the dragon and seeing 40 00:02:34,954 --> 00:02:38,290 the bones of all the explorers who came before you. 41 00:02:40,293 --> 00:02:42,928 ROWE: What cataclysmic force tore these giant 42 00:02:43,029 --> 00:02:45,430 cavities in the galactic gas clouds? 43 00:02:48,668 --> 00:02:51,737 As we fly next to a brilliant shaft of energy 44 00:02:54,240 --> 00:02:58,644 thousands of light-years from M87 star, 45 00:02:58,745 --> 00:02:59,878 we get a clue. 46 00:03:03,616 --> 00:03:04,883 It's a deadly stream of 47 00:03:04,984 --> 00:03:08,720 radiation shooting out across the galaxy, 48 00:03:08,821 --> 00:03:10,522 a jet. 49 00:03:10,623 --> 00:03:13,825 This jet looks like a searchlight 50 00:03:13,927 --> 00:03:17,062 or a beam from a lighthouse. 51 00:03:17,163 --> 00:03:18,897 PLAIT: You're seeing this monumental thing. 52 00:03:18,998 --> 00:03:20,899 It's screaming out of the black hole, 53 00:03:21,000 --> 00:03:22,834 blasting out radiation. 54 00:03:22,936 --> 00:03:28,907 When I first saw a photo of a jet, I was like, "Whoa!" 55 00:03:29,008 --> 00:03:30,209 Am I like, misreading the scale 56 00:03:30,310 --> 00:03:31,944 of this image? Because there was this 57 00:03:32,045 --> 00:03:35,581 crazy Star Trek like beam just coming out. 58 00:03:37,984 --> 00:03:41,720 ROWE: In 1918, American astronomer Heber Curtis 59 00:03:41,821 --> 00:03:45,691 described the jets as a curious straight ray. 60 00:03:47,894 --> 00:03:51,430 A century later, observatory images 61 00:03:51,531 --> 00:03:55,467 reveal they pulsate with energy. 62 00:03:55,568 --> 00:04:00,005 SUTTER: The images show knots and clumps in these jets. 63 00:04:00,106 --> 00:04:03,709 They show that it's just not smooth and nice, 64 00:04:03,810 --> 00:04:07,512 that there's been a history of violence inside this jet. 65 00:04:10,316 --> 00:04:12,651 ROWE: This violent energy pushes 66 00:04:12,752 --> 00:04:15,520 the knots along the beams. 67 00:04:15,622 --> 00:04:18,423 The knots reveal the speed of the jets. 68 00:04:18,524 --> 00:04:21,326 [train whistle blows] 69 00:04:21,427 --> 00:04:23,428 It's like looking at a fast-moving train. 70 00:04:25,331 --> 00:04:29,668 Rail cars of the same color blur into one continuous image. 71 00:04:32,038 --> 00:04:36,708 But different-colored cars stand out against the others. 72 00:04:38,077 --> 00:04:41,913 It's the same with the knots moving along the jets. 73 00:04:42,015 --> 00:04:45,651 So we can figure out how fast the jets are 74 00:04:45,752 --> 00:04:48,487 really moving by looking at knots of material coming out 75 00:04:48,588 --> 00:04:49,821 from near the black hole. 76 00:04:51,357 --> 00:04:54,593 ROWE: When astronomers measured the speed of two knots, 77 00:04:54,694 --> 00:04:56,495 they got a big surprise. 78 00:04:56,596 --> 00:05:00,465 One is moving at 2.4 times the speed of light, 79 00:05:00,566 --> 00:05:04,369 and the other is moving over six times faster than light. 80 00:05:04,470 --> 00:05:06,338 How could this possibly be? 81 00:05:07,807 --> 00:05:10,509 As weird as the physics around a black hole is, 82 00:05:10,610 --> 00:05:13,812 that's not actually happening, nor is it allowed to happen. 83 00:05:13,913 --> 00:05:16,948 SUTTER: Nothing can actually go faster than the speed of light, 84 00:05:17,050 --> 00:05:19,885 so obviously, we're missing something here. 85 00:05:21,788 --> 00:05:25,524 ROWE: The knots may seem to break the speed of light, 86 00:05:25,625 --> 00:05:28,126 but the universe is just playing with us. 87 00:05:28,227 --> 00:05:32,097 It's really just a consequence of the fact that 88 00:05:32,198 --> 00:05:34,766 a lot of this jet is pointed toward us, 89 00:05:34,867 --> 00:05:38,103 pointed partially toward the observer on Earth. 90 00:05:39,472 --> 00:05:41,707 That, in a sense, is a sort of optical illusion 91 00:05:41,808 --> 00:05:44,042 that tricks you into thinking it's moving faster. 92 00:05:45,778 --> 00:05:47,679 ROWE: It's a simple trick of the light, 93 00:05:47,780 --> 00:05:51,950 a bit like the way a spoon in a glass of water looks bent 94 00:05:52,051 --> 00:05:53,385 and distorted. 95 00:05:53,486 --> 00:05:55,987 The impossibly fast speed of the jet 96 00:05:56,089 --> 00:05:59,091 is just an illusion of perspective. 97 00:05:59,192 --> 00:06:01,626 From our perspective, it looks like the whole 98 00:06:01,728 --> 00:06:03,862 thing is moving towards us faster than light. 99 00:06:03,963 --> 00:06:07,366 But really, it's just cruising along very, very fast. 100 00:06:09,268 --> 00:06:11,203 The jets aren't actually breaking the laws of physics. 101 00:06:11,304 --> 00:06:12,704 They're pushing up against it. 102 00:06:12,805 --> 00:06:18,310 They're going at 99.999995% the speed of light. 103 00:06:18,411 --> 00:06:20,812 Imagine the energies necessary 104 00:06:20,913 --> 00:06:24,349 to accelerate this entire jet to that speed. 105 00:06:26,552 --> 00:06:30,622 ROWE: So what could produce enough energy to blast jets 106 00:06:30,723 --> 00:06:35,427 across the galaxy at close to the speed of light? 107 00:06:35,528 --> 00:06:38,430 There is a clue far ahead. 108 00:06:38,531 --> 00:06:40,532 The jets shoot out from 109 00:06:40,633 --> 00:06:43,969 a tiny, brightly glowing object. 110 00:06:44,070 --> 00:06:46,338 This is where things go nuts. 111 00:06:46,439 --> 00:06:48,039 This is the center of the action. 112 00:06:48,141 --> 00:06:52,177 This is where the real stuff happens. 113 00:06:52,278 --> 00:06:54,679 ROWE: A ring of super hot gas 114 00:06:54,781 --> 00:06:59,084 and dust whirls around the supermassive black hole. 115 00:06:59,185 --> 00:07:02,554 It's called the accretion disk, 116 00:07:02,655 --> 00:07:06,291 and it shines a billion times brighter than the sun. 117 00:07:08,761 --> 00:07:13,465 If you had a ringside seat next to M87 star, 118 00:07:13,566 --> 00:07:17,235 you would probably be fried very, very fast. 119 00:07:21,607 --> 00:07:23,909 But if you were some, you know, magical being and could survive 120 00:07:24,010 --> 00:07:25,310 anything, and if you had, 121 00:07:25,411 --> 00:07:27,946 you know, million SPF sunscreen and really, 122 00:07:28,047 --> 00:07:30,415 really great sunglasses, what you would see is this 123 00:07:30,550 --> 00:07:37,422 enormously bright vortex of gas swirling this dark void. 124 00:07:37,523 --> 00:07:39,758 ROWE: This bright vortex spins around 125 00:07:39,859 --> 00:07:42,027 the supermassive black hole, 126 00:07:42,128 --> 00:07:44,763 at over two million miles an hour. 127 00:07:44,864 --> 00:07:47,065 PLAIT: So there's a tremendous amount of friction as 128 00:07:47,133 --> 00:07:50,469 material moving slower and faster rubs against each other. 129 00:07:50,570 --> 00:07:52,170 That's what's heating the disk up, 130 00:07:52,271 --> 00:07:54,105 and that's what's causing it to glow. 131 00:07:57,376 --> 00:07:59,711 ROWE: Scientists think that the intense energy of 132 00:07:59,812 --> 00:08:03,114 the accretion disk is the source of the jets. 133 00:08:03,216 --> 00:08:05,450 The hot, swirling gas 134 00:08:05,551 --> 00:08:09,454 and dust produces powerful magnetic fields. 135 00:08:09,555 --> 00:08:13,925 As the disk spins, it twists up the magnetic fields 136 00:08:14,026 --> 00:08:15,927 at the poles of the black hole. 137 00:08:16,028 --> 00:08:18,163 Energy builds. 138 00:08:18,264 --> 00:08:20,632 Finally, the magnetic fields can't 139 00:08:20,733 --> 00:08:22,434 contain the energy any longer. 140 00:08:24,370 --> 00:08:28,707 They snap and blast the jets out into he galaxy. 141 00:08:28,808 --> 00:08:30,909 Even many light-ears away on the ship, 142 00:08:31,010 --> 00:08:35,614 we can see this violent release of energy. 143 00:08:35,715 --> 00:08:40,252 It's like the universe's biggest fireworks display. 144 00:08:40,353 --> 00:08:42,821 Two jets streaking out of 145 00:08:42,922 --> 00:08:46,124 M87 star's poles, 146 00:08:46,225 --> 00:08:48,393 one shooting away into the distance, 147 00:08:49,929 --> 00:08:52,230 the other racing past our ship. 148 00:08:53,933 --> 00:08:56,301 We're at a safe distance. 149 00:08:56,402 --> 00:08:59,271 Other things are not. 150 00:08:59,372 --> 00:09:02,040 So when these jets shoot outward from the supermassive 151 00:09:02,141 --> 00:09:04,276 black hole, they don't shoot outward into nothing. 152 00:09:04,377 --> 00:09:07,812 If a jet hits a gas cloud, it annihilates it. 153 00:09:07,914 --> 00:09:11,149 It just punches a hole right through it. 154 00:09:11,250 --> 00:09:14,719 It's like a train going down a snowy track, right? 155 00:09:14,820 --> 00:09:16,354 The gas is like the snow 156 00:09:16,455 --> 00:09:19,958 and the jets are like this freight train plowing across it. 157 00:09:20,059 --> 00:09:22,193 ROWE: But here, 158 00:09:22,295 --> 00:09:25,797 a freight train traveling at close to the speed of light, 159 00:09:28,134 --> 00:09:30,201 smashing into clouds of gas, 160 00:09:34,206 --> 00:09:37,709 lighting our way to M87 star 161 00:09:37,810 --> 00:09:40,245 as we follow the trail of destruction. 162 00:09:44,650 --> 00:09:47,886 There is evidence of similar destruction across the universe. 163 00:09:50,122 --> 00:09:54,025 In the Cygnus A galaxy, supermassive black hole jets 164 00:09:54,126 --> 00:09:56,828 have caused damage on a colossal scale. 165 00:09:59,031 --> 00:10:00,465 TREMBLAY: In many ways, Cygnus A is like 166 00:10:00,566 --> 00:10:02,000 a cosmic shooting gallery. 167 00:10:02,101 --> 00:10:06,071 You see this crime scene, this beautiful mess. 168 00:10:06,205 --> 00:10:09,007 OLUSEYI: So when this jet comes out of the nucleus of Cygnus A, 169 00:10:09,108 --> 00:10:11,610 it's gonna encounter gas clouds. 170 00:10:11,711 --> 00:10:15,347 At that point, shockwaves set up, and this jet just rips 171 00:10:15,448 --> 00:10:16,648 right through this material, 172 00:10:16,749 --> 00:10:18,783 sending shock waves in every direction, 173 00:10:18,884 --> 00:10:22,053 creating absolute chaos. 174 00:10:22,154 --> 00:10:25,657 It's hard to believe how much devastation these jets 175 00:10:25,758 --> 00:10:27,258 can cause... they're punching 176 00:10:27,360 --> 00:10:30,095 a hole in the gas 100,000 light-years wide. 177 00:10:30,196 --> 00:10:35,266 I mean, that's... that's the scale of an entire galaxy. 178 00:10:39,639 --> 00:10:41,373 ROWE: As we head towards the center of 179 00:10:41,474 --> 00:10:45,276 the M87 galaxy, we enter hostile territory. 180 00:10:46,646 --> 00:10:49,948 The closer to the supermassive black hole we travel, 181 00:10:50,049 --> 00:10:51,516 the more dangerous it gets. 182 00:10:52,852 --> 00:10:56,287 As we approach the central core of M87, 183 00:10:56,389 --> 00:10:57,622 we start to feel it. 184 00:10:57,723 --> 00:11:00,825 But all this energy, all this ferociousness, 185 00:11:00,926 --> 00:11:02,627 is powered by that black hole. 186 00:11:04,430 --> 00:11:06,931 ROWE: Intense winds start to buffet the ship. 187 00:11:09,902 --> 00:11:14,105 They push away vital gas, quenching star birth. 188 00:11:16,275 --> 00:11:18,910 Could these winds end up killing 189 00:11:19,011 --> 00:11:22,814 the galaxy and M87 star itself? 190 00:11:36,696 --> 00:11:38,096 ROWE: We're on a mission to explore 191 00:11:38,197 --> 00:11:42,267 the supermassive black hole M87 star. 192 00:11:44,937 --> 00:11:49,140 First, we have to cross the M87 galaxy. 193 00:11:49,241 --> 00:11:53,044 It's 120,000 light-years across, 194 00:11:53,145 --> 00:11:56,548 and it looks like a giant puffball. 195 00:11:56,649 --> 00:11:59,217 M87 is an absolute monster. 196 00:11:59,318 --> 00:12:02,053 It's a giant, elliptical galaxy, and that 197 00:12:02,154 --> 00:12:05,290 means that, as you go from the edges to the interior, 198 00:12:05,391 --> 00:12:09,427 you see a higher and higher density of stars. 199 00:12:09,528 --> 00:12:13,865 ROWE: This vast galaxy contains several trillion stars. 200 00:12:13,966 --> 00:12:18,303 What's strange is that almost all of them are the same color. 201 00:12:20,873 --> 00:12:22,841 So as you see, you are... 202 00:12:22,942 --> 00:12:28,913 Your sky is covered with countless red points of light 203 00:12:29,014 --> 00:12:30,348 everywhere you look. 204 00:12:31,584 --> 00:12:34,085 ROWE: Most of these points of light are small, 205 00:12:34,186 --> 00:12:37,889 long living-stars called red dwarfs. 206 00:12:37,990 --> 00:12:40,158 So what happened to the different-colored 207 00:12:40,259 --> 00:12:42,694 stars that we see in other galaxies? 208 00:12:44,196 --> 00:12:45,730 When you create lots of stars, 209 00:12:45,831 --> 00:12:47,999 you make lots of blue and red stars. 210 00:12:48,100 --> 00:12:49,534 But the blue ones don't last very long. 211 00:12:49,635 --> 00:12:51,503 They explode and are gone. 212 00:12:51,604 --> 00:12:53,605 The red ones, the ones that are lower mass, 213 00:12:53,706 --> 00:12:55,907 those are the ones that live for many, many billions 214 00:12:56,008 --> 00:12:58,409 of years... M87 hasn't made stars 215 00:12:58,511 --> 00:13:02,714 in so long that its stars are mostly red. 216 00:13:02,815 --> 00:13:05,617 ROWE: We call galaxies with mainly red stars, 217 00:13:05,718 --> 00:13:08,520 red and dead. 218 00:13:08,621 --> 00:13:11,322 So the only stars that are left in these 219 00:13:11,423 --> 00:13:13,625 red and dead galaxies are billions of 220 00:13:13,726 --> 00:13:15,560 year-old populations. 221 00:13:15,661 --> 00:13:17,695 And since it's not making new stars, 222 00:13:17,797 --> 00:13:21,065 the clock is ticking on M87. 223 00:13:21,167 --> 00:13:24,002 Essentially, it's a dead galaxy walking. 224 00:13:24,103 --> 00:13:26,805 ROWE: The M87 galaxy 225 00:13:26,906 --> 00:13:30,542 hasn't made any new stars for billions of years. 226 00:13:30,643 --> 00:13:33,978 Something had to make that happen. 227 00:13:34,079 --> 00:13:38,449 Something had to deplete or heat up or push away 228 00:13:38,551 --> 00:13:41,152 the gas in those galaxies that would otherwise go into 229 00:13:41,253 --> 00:13:42,253 forming stars. 230 00:13:42,354 --> 00:13:44,589 We think that black holes in the centers 231 00:13:44,690 --> 00:13:48,293 of galaxies are the ultimate answer to this. 232 00:13:48,394 --> 00:13:51,729 ROWE: So how did M87 star 233 00:13:51,831 --> 00:13:54,966 kill off star formation billions of years ago? 234 00:13:56,635 --> 00:13:59,604 As we cruise towards the supermassive black hole, 235 00:13:59,705 --> 00:14:03,441 we get a clue from the strong winds buffeting the ship. 236 00:14:05,411 --> 00:14:08,947 So these winds can be incredibly powerful and really, 237 00:14:09,048 --> 00:14:10,014 really fast, right? 238 00:14:10,115 --> 00:14:11,683 You think a hurricane on Earth is bad? 239 00:14:11,784 --> 00:14:13,251 You should see some of these winds. 240 00:14:14,987 --> 00:14:17,388 ROWE: In space, winds were made up of gas 241 00:14:17,489 --> 00:14:19,157 and superheated plasma. 242 00:14:20,626 --> 00:14:24,329 The power that generates the winds lies ahead 243 00:14:24,430 --> 00:14:28,633 the bright accretion disk surrounding M87 star. 244 00:14:28,734 --> 00:14:31,336 Because it's so incredibly hot, 245 00:14:31,437 --> 00:14:33,538 it liberates an enormous amount of light, 246 00:14:33,639 --> 00:14:36,808 and that light can drive a wind, 247 00:14:36,909 --> 00:14:38,910 and so black holes can power winds. 248 00:14:39,011 --> 00:14:42,313 They power winds with light itself. 249 00:14:42,414 --> 00:14:44,215 And the more material 250 00:14:44,316 --> 00:14:45,984 that's falling into that accretion disk, 251 00:14:46,085 --> 00:14:49,187 the bigger and hotter it gets, and the more powerful the wind 252 00:14:49,288 --> 00:14:51,589 is that the black hole blows. 253 00:14:51,690 --> 00:14:54,792 ROWE: We understand that light from the accretion disk 254 00:14:54,894 --> 00:14:56,594 creates the winds, 255 00:14:56,695 --> 00:14:59,397 but that is about all we know. 256 00:14:59,498 --> 00:15:01,132 We don't know that much about the wind. 257 00:15:01,233 --> 00:15:03,801 Is it expanding in all directions like a sphere? 258 00:15:03,903 --> 00:15:06,638 Or is it aimed in jets, very narrow 259 00:15:06,739 --> 00:15:09,607 and only moving in two different directions? 260 00:15:09,708 --> 00:15:11,309 Now, measuring the effect of the winds 261 00:15:11,410 --> 00:15:12,677 isn't as easy as you might think. 262 00:15:12,778 --> 00:15:14,545 It's not like going outside on a windy day 263 00:15:14,647 --> 00:15:16,014 and doing one of these. 264 00:15:16,115 --> 00:15:18,316 You have to infer what's going on with the winds 265 00:15:18,417 --> 00:15:20,919 by studying the light emanating from this object. 266 00:15:23,222 --> 00:15:25,890 ROWE: We wanted to find out if black hole winds 267 00:15:25,991 --> 00:15:30,628 expand like a bubble or travel in narrow streams. 268 00:15:30,729 --> 00:15:33,231 So we studied how iron dust from 269 00:15:33,332 --> 00:15:37,769 the accretion disk blocks the light driving the wind. 270 00:15:37,870 --> 00:15:41,272 Astronomers found the answer when they looked 271 00:15:41,373 --> 00:15:43,374 in the X-ray light spectrum. 272 00:15:45,177 --> 00:15:47,111 And what they detected was iron 273 00:15:47,212 --> 00:15:49,681 absorbing those X-rays in every direction 274 00:15:49,782 --> 00:15:51,215 they looked around the black hole. 275 00:15:51,317 --> 00:15:52,550 That's only possible 276 00:15:52,651 --> 00:15:55,887 if the black hole is blowing out a wind in every direction, 277 00:15:55,988 --> 00:15:58,423 which means that it is definitely blowing out 278 00:15:58,524 --> 00:16:01,759 a spherical wind, which is expanding into that galaxy. 279 00:16:01,860 --> 00:16:04,662 And so these black holes can almost literally inflate 280 00:16:04,763 --> 00:16:06,931 this growing sphere bubble 281 00:16:07,032 --> 00:16:10,034 of gas that's outward flowing from the heart of the galaxy. 282 00:16:12,705 --> 00:16:16,774 These winds push out throughout the entire 283 00:16:16,875 --> 00:16:18,376 galaxy of M87, 284 00:16:18,477 --> 00:16:22,813 transporting heat and energy throughout the entire volume of 285 00:16:22,881 --> 00:16:24,415 the galaxy. 286 00:16:24,516 --> 00:16:27,552 PLAIT: What we found is that it's expanding away 287 00:16:27,653 --> 00:16:29,887 from the black hole at a quarter of 288 00:16:29,989 --> 00:16:34,125 the speed of light, 40,000 miles per second. 289 00:16:36,128 --> 00:16:37,929 ROWE: And for the M87 galaxy, 290 00:16:38,030 --> 00:16:40,665 that is bad news, because hot, 291 00:16:40,766 --> 00:16:44,769 powerful winds kill off star birth. 292 00:16:44,870 --> 00:16:49,407 The winds can push away the gas that would have normally 293 00:16:49,508 --> 00:16:51,275 formed stars so they can 294 00:16:51,377 --> 00:16:55,013 effectively quench star formation in a galaxy, 295 00:16:55,114 --> 00:16:57,415 causing it to gradually die. 296 00:17:00,252 --> 00:17:02,453 ROWE: And it gets worse. 297 00:17:02,554 --> 00:17:04,889 In order for a galaxy to produce stars, 298 00:17:04,990 --> 00:17:06,891 it needs lots of gas and dust, 299 00:17:06,992 --> 00:17:11,162 and that gas and dust needs to be incredibly cold. 300 00:17:11,263 --> 00:17:13,231 ROWE: Hot winds from the black hole heat up 301 00:17:13,332 --> 00:17:17,201 gas clouds so they can't collapse into stars. 302 00:17:17,302 --> 00:17:20,505 As M87 star has grown, 303 00:17:20,606 --> 00:17:25,043 it has slowly shut down star formation. 304 00:17:25,144 --> 00:17:27,412 As the black hole in the center of the galaxy grows, 305 00:17:27,513 --> 00:17:29,514 it has stronger and stronger winds, 306 00:17:29,615 --> 00:17:32,817 and this means it's gonna drive out more and more matter. 307 00:17:32,918 --> 00:17:34,886 And that's what makes it a galaxy 308 00:17:34,987 --> 00:17:37,922 that can no longer support star formation. 309 00:17:38,023 --> 00:17:41,159 MINGARELLI: So a supermassive black hole can determine 310 00:17:41,260 --> 00:17:43,628 the star formation happening in the galaxy. 311 00:17:43,729 --> 00:17:46,864 It can help to regulate the amount of gas in the galaxy 312 00:17:46,965 --> 00:17:49,467 and therefore the number of stars that are formed 313 00:17:49,568 --> 00:17:51,369 in a galaxy. 314 00:17:51,470 --> 00:17:55,139 ROWE: Although M87 star is tiny 315 00:17:55,240 --> 00:17:57,708 compared to the vast galaxy around it, 316 00:17:57,810 --> 00:18:00,778 it still controls its host. 317 00:18:02,247 --> 00:18:04,849 When you compare it to the size of the galaxy 318 00:18:04,950 --> 00:18:06,751 it's sitting in, it's like comparing 319 00:18:06,852 --> 00:18:09,253 a grape to the size of the Earth. 320 00:18:09,354 --> 00:18:12,190 So to think that something so relatively small compared to 321 00:18:12,291 --> 00:18:15,626 the galaxy could have such a profound effect over 322 00:18:15,727 --> 00:18:18,129 effectively all of cosmic history is 323 00:18:18,230 --> 00:18:21,566 just this remarkable illustration of how energetic 324 00:18:21,633 --> 00:18:23,201 a black hole can be. 325 00:18:23,302 --> 00:18:24,769 In the relationship between 326 00:18:24,870 --> 00:18:28,806 a supermassive black hole and the material surrounding it, 327 00:18:28,907 --> 00:18:31,142 the black hole is in charge. 328 00:18:33,011 --> 00:18:36,881 ROWE: Although M87 star calls the shots, its past, 329 00:18:36,982 --> 00:18:40,384 present, and future are inextricably linked 330 00:18:40,486 --> 00:18:41,819 to its host galaxy. 331 00:18:43,922 --> 00:18:47,024 The view from our ship is endless space, 332 00:18:47,126 --> 00:18:49,260 calm and unchanging. 333 00:18:51,830 --> 00:18:55,099 But the M87 galaxy has a violent past, 334 00:18:56,468 --> 00:18:59,470 a history of cannibalism, 335 00:18:59,571 --> 00:19:01,405 death, and destruction. 336 00:19:12,451 --> 00:19:15,019 ROWE: We've traveled thousands of light-years 337 00:19:15,120 --> 00:19:17,054 across the M87 galaxy, 338 00:19:17,156 --> 00:19:19,724 but its supermassive black hole 339 00:19:19,825 --> 00:19:22,693 is still far in the distance. 340 00:19:22,794 --> 00:19:25,196 From our current position, 341 00:19:25,297 --> 00:19:28,199 M87 star may look small, 342 00:19:28,300 --> 00:19:33,504 but it's 6.5 billion times the mass of the sun. 343 00:19:33,605 --> 00:19:36,407 So how did it get so big? 344 00:19:36,508 --> 00:19:38,709 One of the big mysteries that we're still trying to 345 00:19:38,810 --> 00:19:40,444 understand is what 346 00:19:40,546 --> 00:19:43,381 controls how big the giant black holes at the centers of 347 00:19:43,482 --> 00:19:44,982 galaxies become. 348 00:19:45,083 --> 00:19:48,019 And we know that it's tightly correlated 349 00:19:48,120 --> 00:19:50,021 with things like how big the galaxy is. 350 00:19:50,122 --> 00:19:53,925 Bigger galaxies have bigger black holes. 351 00:19:54,026 --> 00:19:58,663 ROWE: To understand how M87 star became so big, we have to 352 00:19:58,764 --> 00:20:01,332 investigate the history of its galaxy. 353 00:20:01,433 --> 00:20:06,304 We need to discover how M87 star's host galaxy 354 00:20:06,405 --> 00:20:08,472 grew so large. 355 00:20:08,574 --> 00:20:11,442 M87 is huge. 356 00:20:11,543 --> 00:20:15,479 It's a big galaxy with a big black hole. 357 00:20:15,581 --> 00:20:17,248 TREMBLAY: It's really, really big. 358 00:20:17,349 --> 00:20:19,150 It's what we call the brightest cluster galaxy, 359 00:20:19,251 --> 00:20:22,153 and these so-called brightest cluster galaxies are among 360 00:20:22,254 --> 00:20:25,122 the most massive galaxies in the known universe. 361 00:20:25,224 --> 00:20:30,261 Usually, a galaxy with the mass of M87 is much smaller, 362 00:20:30,362 --> 00:20:35,132 but M87 is puffed up hugely. Why? 363 00:20:35,234 --> 00:20:40,137 ROWE: One lead comes from the layout of M87's stars. 364 00:20:40,239 --> 00:20:42,773 As we travel through the galaxy, we see 365 00:20:42,841 --> 00:20:46,611 that the stars spread out over an area 100 times larger 366 00:20:46,712 --> 00:20:48,646 than expected. 367 00:20:48,747 --> 00:20:51,382 So what scattered the stars? 368 00:20:52,951 --> 00:20:56,587 Galaxies aren't static, every galaxy is moving, 369 00:20:56,688 --> 00:20:58,990 and sometimes galaxies get very close 370 00:20:59,057 --> 00:21:00,825 and can interact with each other. 371 00:21:02,227 --> 00:21:04,362 ROWE: Interact is a polite way 372 00:21:04,463 --> 00:21:07,932 of describing something extremely brutal. 373 00:21:08,033 --> 00:21:11,535 Galaxies are colliding with other galaxies, they're 374 00:21:11,637 --> 00:21:15,072 cannibalizing smaller galaxies or tearing each other apart. 375 00:21:17,876 --> 00:21:19,944 MINGARELLI: Sometimes they're like drive-bys, 376 00:21:20,045 --> 00:21:22,947 and they'll warp each other's structures. 377 00:21:23,048 --> 00:21:27,585 Sometimes the galaxies have head-on collisions and merge. 378 00:21:27,686 --> 00:21:31,789 ROWE: Merging pulls in new gas and stars, 379 00:21:31,890 --> 00:21:35,059 so galaxies grow larger. 380 00:21:37,863 --> 00:21:39,930 Galactic cannibalism is common. 381 00:21:43,168 --> 00:21:46,704 Maybe the M87 galaxy ate its neighbors. 382 00:21:48,440 --> 00:21:49,774 But how can we find out? 383 00:21:51,543 --> 00:21:53,477 We could try to identify stars 384 00:21:53,578 --> 00:21:55,880 that came from the consumed galaxies, 385 00:21:57,949 --> 00:22:00,318 but that's not straightforward. 386 00:22:00,419 --> 00:22:02,653 When you're trying to map out a distant galaxy, 387 00:22:02,754 --> 00:22:05,489 it turns out using their stars is a really hard thing to do. 388 00:22:05,590 --> 00:22:08,326 They smear in with the foreground and the background. 389 00:22:08,427 --> 00:22:09,827 It's actually very difficult to see any 390 00:22:09,928 --> 00:22:11,996 evidence that that galaxy merger ever happened. 391 00:22:12,097 --> 00:22:13,564 It's all smoothed out. 392 00:22:13,665 --> 00:22:16,200 It's kind of like throwing a bucket of water into a pond. 393 00:22:16,301 --> 00:22:18,402 And then asking after the waves go away 394 00:22:18,503 --> 00:22:21,472 to separate which molecules of water came from 395 00:22:21,573 --> 00:22:23,874 the pail of water versus which were in the pond. 396 00:22:23,975 --> 00:22:27,011 All you see is just mixed pile of water, 397 00:22:27,112 --> 00:22:29,613 and it's similar to that with the stars in a galaxy. 398 00:22:32,017 --> 00:22:34,051 ROWE: So how can you spot water from the bucket 399 00:22:34,152 --> 00:22:35,686 in the pond water? 400 00:22:37,622 --> 00:22:41,192 We need to detect signs of disruption, 401 00:22:41,293 --> 00:22:43,194 like ripples or distinct 402 00:22:43,295 --> 00:22:45,696 streaks of sand and mud thrown up 403 00:22:45,797 --> 00:22:47,465 by the disturbance. 404 00:22:47,566 --> 00:22:51,068 When galaxies merge, they may also 405 00:22:51,169 --> 00:22:54,038 leave a leftover that stands out, 406 00:22:54,139 --> 00:22:56,440 like a planetary nebula. 407 00:22:56,541 --> 00:22:59,677 Planetary nebulae are these bright beacons that you can 408 00:22:59,778 --> 00:23:03,280 pick out and map out the galaxy with great precision. 409 00:23:03,382 --> 00:23:06,984 ROWE: A planetary nebula forms when a dying, 410 00:23:07,085 --> 00:23:10,287 mid-sized star blows off its outer layers 411 00:23:10,389 --> 00:23:13,891 after running out of fuel... These outer layers of 412 00:23:13,992 --> 00:23:16,694 gas expand, forming a nebula, 413 00:23:16,795 --> 00:23:19,930 often in the shape of a ring or bubble. 414 00:23:20,031 --> 00:23:23,968 And you see this beautiful, glowing blue-green blob coming 415 00:23:24,069 --> 00:23:26,604 away from the star... these are so much bigger than stars. 416 00:23:26,705 --> 00:23:28,706 You can pick them out very easily. 417 00:23:28,807 --> 00:23:32,443 ROWE: One team went planetary nebula hunting 418 00:23:32,544 --> 00:23:34,979 in the M87 galaxy. 419 00:23:35,080 --> 00:23:36,881 As they mapped the galaxy, 420 00:23:36,982 --> 00:23:40,518 they picked out 300 distinct glowing points. 421 00:23:42,387 --> 00:23:45,356 The points are blue-green, confirming they're 422 00:23:45,457 --> 00:23:46,624 planetary nebulas. 423 00:23:49,461 --> 00:23:51,262 Planetary nebulae are great. 424 00:23:51,363 --> 00:23:53,531 They really stand out like needles in 425 00:23:53,632 --> 00:23:55,332 a planetary haystack. 426 00:23:55,434 --> 00:23:57,234 ROWE: The nebula's movements are distinct 427 00:23:57,335 --> 00:23:59,770 from the stars in M87. 428 00:23:59,871 --> 00:24:04,041 This shows they formed in a smaller, younger galaxy, 429 00:24:04,142 --> 00:24:06,410 not M87. 430 00:24:06,511 --> 00:24:08,379 THALLER: Because we see these planetary nebulae, 431 00:24:08,480 --> 00:24:11,215 something must have happened in this old, dead galaxy. 432 00:24:11,316 --> 00:24:14,518 What was it? A galaxy collision. 433 00:24:14,619 --> 00:24:17,955 ROWE: The discovery of the planetary nebulas 434 00:24:18,056 --> 00:24:21,192 shows that at some point in the last billion years 435 00:24:21,293 --> 00:24:24,929 M87 ate a smaller galaxy. 436 00:24:27,299 --> 00:24:31,502 This galaxy strayed too close to the much larger M87. 437 00:24:34,673 --> 00:24:39,109 M87's powerful gravity snared the smaller galaxy 438 00:24:39,211 --> 00:24:42,279 and dragged it closer and closer. 439 00:24:42,380 --> 00:24:45,583 You could actually see this galaxy getting bigger 440 00:24:45,684 --> 00:24:47,151 and bigger and bigger in the sky, 441 00:24:47,252 --> 00:24:49,987 and it wouldn't stay the same shape... as the galaxy 442 00:24:50,088 --> 00:24:52,122 got closer, it would begin to distort, 443 00:24:52,224 --> 00:24:55,860 and your galaxy would distort, as well, until the sky was 444 00:24:55,961 --> 00:24:57,928 filled with rivers of stars. 445 00:25:01,633 --> 00:25:06,437 M87 pulled in the small galaxy and swallowed it whole. 446 00:25:09,307 --> 00:25:10,341 Can you think of anything more 447 00:25:10,442 --> 00:25:13,511 dramatic than the collision of two galaxies? 448 00:25:13,612 --> 00:25:16,280 ROWE: A violent history of mergers explains how 449 00:25:16,381 --> 00:25:19,116 the M87 galaxy grew so large. 450 00:25:21,520 --> 00:25:24,622 Each event brought in many millions of stars. 451 00:25:26,725 --> 00:25:30,995 The collisions also unleashed enormous gravitational forces, 452 00:25:33,398 --> 00:25:36,400 scattering the stars like confetti. 453 00:25:36,501 --> 00:25:38,636 OLUSEYI: After a collision like this, 454 00:25:38,737 --> 00:25:42,540 the stars are probably ten to 100 times more spread out 455 00:25:42,641 --> 00:25:44,875 than they were before. 456 00:25:44,976 --> 00:25:48,012 ROWE: Some collisions threw stars around. 457 00:25:48,113 --> 00:25:52,650 Others changed the shape of the entire galaxy. 458 00:25:52,751 --> 00:25:55,786 PLAIT: If that galaxy merger is violent enough, 459 00:25:55,887 --> 00:25:59,823 it injects so much energy into the galaxy that the stars 460 00:25:59,925 --> 00:26:02,059 basically all move away from the center, 461 00:26:02,160 --> 00:26:04,929 and it makes the galaxy much more puffy. 462 00:26:05,030 --> 00:26:08,866 ROWE: Gradually transforming it into the smooth, featureless, 463 00:26:08,967 --> 00:26:10,034 elliptical shape. 464 00:26:14,306 --> 00:26:16,807 Most galaxies have a supermassive black hole 465 00:26:16,908 --> 00:26:17,942 at their center, 466 00:26:18,043 --> 00:26:21,879 including those galaxies eaten by M87. 467 00:26:21,980 --> 00:26:25,416 So what happened to those black holes? 468 00:26:25,517 --> 00:26:30,521 Did they merge with M87 star, increasing its size? 469 00:26:30,622 --> 00:26:33,724 M87, the fact that it's an elliptical galaxy also 470 00:26:33,825 --> 00:26:34,925 supports the fact that it's had 471 00:26:35,060 --> 00:26:38,195 multiple supermassive black hole mergers, which is how 472 00:26:38,296 --> 00:26:41,832 M87 star could have gained its sizable mass. 473 00:26:41,933 --> 00:26:44,969 ROWE: Compared to its violent history, 474 00:26:45,070 --> 00:26:48,405 the M87 galaxy is now relatively calm. 475 00:26:49,774 --> 00:26:51,408 We think that in the past, 476 00:26:51,509 --> 00:26:56,146 M87 star grew by gobbling up other supermassive black holes 477 00:26:56,247 --> 00:26:59,717 brought in by collisions with other galaxies. 478 00:27:04,155 --> 00:27:06,490 But we don't really know, because physics 479 00:27:06,591 --> 00:27:11,395 suggests that supermassive black holes can never merge. 480 00:27:11,496 --> 00:27:14,398 Instead, they lock together 481 00:27:14,499 --> 00:27:17,301 in a cosmic dance for eternity. 482 00:27:28,513 --> 00:27:31,882 ROWE: As we travel closer to the supermassive black hole, 483 00:27:31,983 --> 00:27:33,550 we pass the remnants 484 00:27:33,652 --> 00:27:36,920 of smaller galaxies eaten over the last 485 00:27:37,022 --> 00:27:39,056 10 billion years. 486 00:27:39,157 --> 00:27:44,795 They reveal how the M87 galaxy got so vast. 487 00:27:44,896 --> 00:27:47,898 Most of these consumed galaxies probably had 488 00:27:47,999 --> 00:27:50,200 a supermassive black hole of their own. 489 00:27:52,470 --> 00:27:56,774 If M87 got so large by eating galaxies, 490 00:27:56,875 --> 00:28:00,678 did M87 star get supermassive 491 00:28:00,779 --> 00:28:04,281 by consuming other supermassive black holes? 492 00:28:06,151 --> 00:28:10,688 So when galaxies merge, all their stars and nebulae 493 00:28:10,789 --> 00:28:15,426 mix together, and then also there supermassive black holes 494 00:28:15,527 --> 00:28:19,196 eventually find each other and find their way down to 495 00:28:19,297 --> 00:28:21,565 the center of the newly merged galaxy. 496 00:28:21,666 --> 00:28:24,168 Just like dropping two stones into a pond, 497 00:28:24,269 --> 00:28:25,703 they'll both reach the bottom. 498 00:28:25,804 --> 00:28:28,205 They'll both move toward the center, 499 00:28:28,306 --> 00:28:31,341 and they will start to move ever closer together. 500 00:28:31,443 --> 00:28:34,178 ROWE: But do the supermassive black holes 501 00:28:34,279 --> 00:28:36,213 actually collide? 502 00:28:36,314 --> 00:28:38,882 We've witnessed the merging of smaller, 503 00:28:38,983 --> 00:28:41,118 stellar mass black holes, 504 00:28:41,219 --> 00:28:45,489 and we've seen supermassive black holes get close together, 505 00:28:45,590 --> 00:28:49,293 but we've never observed them merge. 506 00:28:49,394 --> 00:28:51,962 When galaxies merge, their central, 507 00:28:52,063 --> 00:28:54,131 supermassive black holes should merge. 508 00:28:54,232 --> 00:28:56,166 The first step in the merger process, 509 00:28:56,267 --> 00:28:58,402 they're sinking toward the center of 510 00:28:58,503 --> 00:29:00,337 this newly formed galaxy. 511 00:29:00,438 --> 00:29:03,574 ROWE: As they plunge towards the galactic center, 512 00:29:03,675 --> 00:29:06,443 the supermassive black holes plow through fields 513 00:29:06,544 --> 00:29:08,946 of stars and clouds of gas. 514 00:29:10,448 --> 00:29:12,182 They don't just run into each other, 515 00:29:12,283 --> 00:29:14,885 they inspiral toward each other, so they're gonna 516 00:29:14,986 --> 00:29:18,622 scatter stars everywhere, and the closer they get 517 00:29:18,723 --> 00:29:21,492 the more rapidly they will orbit each other. 518 00:29:21,593 --> 00:29:24,962 So things get even more and more chaotic and crazy. 519 00:29:26,431 --> 00:29:30,100 ROWE: In all the chaos, something strange happens. 520 00:29:30,201 --> 00:29:33,504 The supermassive black holes stop moving 521 00:29:33,605 --> 00:29:36,206 closer to each other. 522 00:29:36,307 --> 00:29:39,910 This is a problem, and we call this the final parsec problem. 523 00:29:41,412 --> 00:29:43,347 ROWE: So what's going on? 524 00:29:43,448 --> 00:29:45,516 Why do they stall? 525 00:29:45,617 --> 00:29:47,117 MINGARELLI: The final parsec problem 526 00:29:47,218 --> 00:29:50,821 happens when two supermassive black holes run out 527 00:29:50,922 --> 00:29:53,056 of material to help them to merge. 528 00:29:53,158 --> 00:29:55,559 If there's not enough stars or gas 529 00:29:55,660 --> 00:29:57,628 that the black holes can interact with, 530 00:29:57,729 --> 00:29:59,363 it takes longer than the age of 531 00:29:59,464 --> 00:30:02,566 the universe for them to lose enough energy to merge. 532 00:30:02,667 --> 00:30:05,102 And so the black holes effectively stall 533 00:30:05,203 --> 00:30:07,371 at this final parsec of separation. 534 00:30:10,074 --> 00:30:12,376 ROWE: The two supermassive black holes lock 535 00:30:12,477 --> 00:30:15,946 together in an eternal cosmic dance, 536 00:30:16,047 --> 00:30:18,982 close but forever apart. 537 00:30:21,586 --> 00:30:25,589 But some supermassive black holes must have merged. 538 00:30:25,690 --> 00:30:28,091 It's highly likely that many of 539 00:30:28,193 --> 00:30:32,596 the galaxies M87 swallowed had supermassive black holes. 540 00:30:34,265 --> 00:30:35,766 And yet, on our trip, 541 00:30:35,867 --> 00:30:39,636 we haven't seen lots of supermassive black holes, 542 00:30:39,737 --> 00:30:42,639 just one... M87 star. 543 00:30:44,642 --> 00:30:48,779 So mergers take place, but how? 544 00:30:51,049 --> 00:30:54,451 In 2019, we got a clue 545 00:30:54,552 --> 00:30:58,689 from a galaxy called NGC 6240. 546 00:30:58,790 --> 00:31:03,493 This particular galaxy looks like 547 00:31:03,595 --> 00:31:07,397 the aftermath of a massive galactic collision. 548 00:31:07,498 --> 00:31:10,500 There are lumps and clumps of stars, 549 00:31:10,602 --> 00:31:12,369 random groups at random directions 550 00:31:12,470 --> 00:31:13,537 and random velocities. 551 00:31:13,638 --> 00:31:16,273 It's all mixed up, which is what we think 552 00:31:16,374 --> 00:31:20,010 galaxies look like after a massive merger. 553 00:31:20,111 --> 00:31:22,613 ROWE: The merger aftermath reveals a more 554 00:31:22,714 --> 00:31:26,083 complex series of events than a two-galaxy collision. 555 00:31:27,485 --> 00:31:30,387 What we find in the center of this galaxy isn't two, 556 00:31:30,488 --> 00:31:33,423 but three giant black holes, 557 00:31:33,524 --> 00:31:37,494 which suggests that there have been three galaxies 558 00:31:37,595 --> 00:31:39,596 colliding in recent history. 559 00:31:42,033 --> 00:31:44,701 MINGARELLI: So when this new galaxy starts to merge 560 00:31:44,802 --> 00:31:47,471 with the galaxy that hosts the stalled pair, 561 00:31:47,572 --> 00:31:51,041 it brings in its own third supermassive black hole. 562 00:31:51,142 --> 00:31:53,810 Now this supermassive black hole perturbs the system, 563 00:31:53,912 --> 00:31:57,447 and it makes what's at the center highly unstable. 564 00:31:57,548 --> 00:32:01,652 ROWE: The gravity of this third supermassive black hole steals 565 00:32:01,753 --> 00:32:04,655 orbital energy from the stalled pair, 566 00:32:04,756 --> 00:32:06,890 pushing them closer together. 567 00:32:06,991 --> 00:32:10,527 It's almost a thief that comes in and takes away 568 00:32:10,628 --> 00:32:13,130 some of that rotational energy from this binary 569 00:32:13,231 --> 00:32:14,398 black hole system. 570 00:32:14,499 --> 00:32:16,934 ROWE: As the two supermassive black holes 571 00:32:17,035 --> 00:32:21,071 lose orbital energy, they finally come together. 572 00:32:21,172 --> 00:32:23,840 The likeliest thing to happen is that the least massive 573 00:32:23,942 --> 00:32:26,610 supermassive black hole is ejected. 574 00:32:28,579 --> 00:32:30,781 And the remaining two merge very quickly. 575 00:32:32,183 --> 00:32:35,886 ROWE: The high-speed merger will last just milliseconds, 576 00:32:35,987 --> 00:32:37,154 but it will trigger 577 00:32:37,255 --> 00:32:38,789 [explosion blasts] 578 00:32:38,890 --> 00:32:41,191 A gigantic explosion. 579 00:32:42,627 --> 00:32:45,462 SUTTER: When these giant black holes merge, 580 00:32:45,563 --> 00:32:49,700 more energy is released in this process than our entire 581 00:32:49,801 --> 00:32:51,535 galaxy will emit 582 00:32:51,636 --> 00:32:55,038 over the course of billions of years. 583 00:32:55,139 --> 00:32:59,109 ROWE: Perhaps M87 star merged 584 00:32:59,210 --> 00:33:01,578 with other supermassive black holes 585 00:33:01,679 --> 00:33:02,512 in the same way... 586 00:33:02,613 --> 00:33:05,615 A third black hole, helping it 587 00:33:05,717 --> 00:33:10,153 to overcome the final parsec problem. 588 00:33:10,254 --> 00:33:12,923 It's possible that mergers with other supermassive 589 00:33:12,991 --> 00:33:16,994 black holes allowed M87 to reach its sizable 590 00:33:17,095 --> 00:33:20,831 mass of 6.5 billion solar masses. 591 00:33:20,932 --> 00:33:23,834 ROWE: Supermassive black holes meet their match 592 00:33:23,935 --> 00:33:26,203 when they square off against each other. 593 00:33:28,373 --> 00:33:31,174 The fallout is cataclysmic, 594 00:33:31,275 --> 00:33:34,478 and as we get closer to M87 star, 595 00:33:34,579 --> 00:33:37,280 our mission becomes more dangerous. 596 00:33:37,382 --> 00:33:40,217 We enter the gravitational kill zone 597 00:33:40,318 --> 00:33:42,519 surrounding the supermassive black hole. 598 00:33:44,288 --> 00:33:46,156 We know the dangers. 599 00:33:46,257 --> 00:33:49,593 Any unwitting stars that get too close are 600 00:33:49,694 --> 00:33:52,229 stretched, shredded, 601 00:33:52,330 --> 00:33:54,164 and torn apart, 602 00:33:54,265 --> 00:33:55,899 creating one of the biggest 603 00:33:56,000 --> 00:33:58,268 and brightest light shows in the universe. 604 00:34:13,418 --> 00:34:15,352 ROWE: As we get closer to M87's 605 00:34:15,453 --> 00:34:17,454 supermassive black hole, 606 00:34:17,555 --> 00:34:22,559 we enter dangerous territory, not just for us, 607 00:34:22,660 --> 00:34:26,363 but also for wandering stars. 608 00:34:26,464 --> 00:34:29,266 If the black hole snares them, 609 00:34:29,367 --> 00:34:31,068 they are toast. 610 00:34:31,169 --> 00:34:34,304 But their death may solve one 611 00:34:34,405 --> 00:34:37,574 of the mysteries of supermassive black holes... 612 00:34:37,675 --> 00:34:39,209 How fast they spin. 613 00:34:41,079 --> 00:34:44,548 It's difficult to calculate just how fast 614 00:34:44,649 --> 00:34:47,350 a featureless black object hidden by 615 00:34:47,452 --> 00:34:50,053 a bright disc rotates. 616 00:34:50,154 --> 00:34:53,156 You need a lot of patience and a little bit of luck. 617 00:34:53,257 --> 00:34:57,027 Astronomy is sometimes a pretty opportunistic science. 618 00:34:57,128 --> 00:34:58,995 You have to be looking at the right place at 619 00:34:59,097 --> 00:35:01,198 the right time to figure out something new 620 00:35:01,299 --> 00:35:04,401 that we've never seen before. 621 00:35:04,502 --> 00:35:06,536 ROWE: Recently, astronomers caught a break 622 00:35:06,637 --> 00:35:09,406 when they spotted an extremely bright flare 623 00:35:09,507 --> 00:35:14,544 in galaxy PGC 043234. 624 00:35:14,645 --> 00:35:18,014 It was hard to miss. 625 00:35:18,116 --> 00:35:22,686 The flare was 100 billion times brighter than the sun. 626 00:35:26,791 --> 00:35:30,093 And the energy output was absolutely ridiculous. 627 00:35:30,194 --> 00:35:32,696 If this happened in the center of our galaxy, 628 00:35:32,797 --> 00:35:35,165 it would have been so bright, we could see it during 629 00:35:35,266 --> 00:35:36,399 the daytime. 630 00:35:36,501 --> 00:35:38,768 [explosion blasts] 631 00:35:38,870 --> 00:35:41,404 ROWE: A routine search for supernovas, 632 00:35:41,506 --> 00:35:46,710 violent deaths of giant stars, detected the intense flash. 633 00:35:46,811 --> 00:35:49,713 ASAS-SN is this network of telescopes 634 00:35:49,814 --> 00:35:52,182 designed to look for brief, 635 00:35:52,283 --> 00:35:55,252 high-energy events all around the sky, 636 00:35:55,319 --> 00:35:56,887 and primarily supernova. 637 00:35:56,988 --> 00:35:59,890 They saw a bright flash, and they thought, "Oh, yay, 638 00:35:59,991 --> 00:36:01,725 another supernova." 639 00:36:05,129 --> 00:36:08,131 If you see a bright flash of light coming from a galaxy, 640 00:36:08,232 --> 00:36:09,699 that's kind of your first thought. 641 00:36:09,800 --> 00:36:12,002 But it didn't look like a supernova at all. 642 00:36:12,103 --> 00:36:15,305 It didn't act like a supernova flash would. 643 00:36:15,406 --> 00:36:17,307 It didn't have the right characteristics. 644 00:36:17,408 --> 00:36:19,609 It wasn't behaving like a typical supernova. 645 00:36:19,710 --> 00:36:21,878 It had to be something else. 646 00:36:21,979 --> 00:36:24,114 SUTTER: So they send out an alert to 647 00:36:24,215 --> 00:36:26,850 the astronomical community, saying, "Hey, there's something 648 00:36:26,951 --> 00:36:29,519 cool happening in this region of space." 649 00:36:29,620 --> 00:36:31,821 Once an event is flagged as real, 650 00:36:31,923 --> 00:36:35,158 then what happens is other telescopes turn their attention 651 00:36:35,259 --> 00:36:36,426 to that event. 652 00:36:38,696 --> 00:36:41,198 ROWE: The data revealed something strange. 653 00:36:41,299 --> 00:36:44,768 SUTTER: After the initial flash, 654 00:36:44,869 --> 00:36:48,305 there are still smaller flashes that repeat, and if 655 00:36:48,406 --> 00:36:50,807 you're gonna kill a star in a supernova, 656 00:36:50,908 --> 00:36:54,544 there's nothing left to repeat like that. 657 00:36:54,645 --> 00:36:57,714 Intriguingly, it flashed on 658 00:36:57,815 --> 00:37:00,584 and off about once every 130 seconds. 659 00:37:00,685 --> 00:37:05,789 ROWE: The flashes continued for 450 days. 660 00:37:05,890 --> 00:37:10,327 PLAIT: When astronomers looked at this galaxy in detail, 661 00:37:10,428 --> 00:37:12,996 they saw that this event happened right at the center, 662 00:37:13,130 --> 00:37:15,966 and there's a black hole there with about one million times 663 00:37:16,067 --> 00:37:18,735 the sun's mass, and that was... That's it, man. 664 00:37:18,836 --> 00:37:20,637 That's the smoking gun. 665 00:37:20,738 --> 00:37:24,774 ROWE: What they observed was an extremely rare phenomenon, 666 00:37:24,875 --> 00:37:27,077 a tidal disruption event. 667 00:37:27,178 --> 00:37:30,113 SUTTER: Catching one live as it happens 668 00:37:30,214 --> 00:37:32,682 is an astronomer's dream. 669 00:37:32,783 --> 00:37:35,518 This was our first time catching a black hole in 670 00:37:35,620 --> 00:37:37,821 the act of feeding on a star. 671 00:37:37,922 --> 00:37:42,259 In galaxy PGC 043234, 672 00:37:42,360 --> 00:37:44,828 a star wandered too close to 673 00:37:44,929 --> 00:37:46,496 a supermassive black hole. 674 00:37:47,898 --> 00:37:52,135 SUTTER: As this unfortunate star got close to the black hole, 675 00:37:52,236 --> 00:37:53,837 the black hole is spinning, 676 00:37:53,938 --> 00:37:58,475 and the gravity around this monster black hole is so strong 677 00:37:58,576 --> 00:38:02,145 that it could pull the star apart. 678 00:38:05,416 --> 00:38:07,717 PLAIT: The side of the star closer to the black hole 679 00:38:07,818 --> 00:38:09,519 is feeling a much, much stronger 680 00:38:09,620 --> 00:38:11,855 gravitational pull toward the black hole than 681 00:38:11,956 --> 00:38:14,557 the far side of the star, because it's farther away. 682 00:38:14,659 --> 00:38:17,060 And what this does is it stretches the star. 683 00:38:19,397 --> 00:38:22,732 SUTTER: So it got ripped to shreds, it got shredded. 684 00:38:22,833 --> 00:38:24,501 It got pulled out and stretched 685 00:38:24,602 --> 00:38:26,703 and whipped around the black hole. 686 00:38:30,174 --> 00:38:33,743 And this stretches the star into some giant long arm, 687 00:38:33,844 --> 00:38:36,413 and that swirls around and is trapped as it orbits 688 00:38:36,514 --> 00:38:38,682 the black hole. 689 00:38:38,783 --> 00:38:42,619 ROWE: The accretion disk snares the shredded star. 690 00:38:42,720 --> 00:38:46,856 OLUSEYI: And what this means is that that accretion disk is 691 00:38:46,957 --> 00:38:51,061 gonna increase its output of radiation, in particular, 692 00:38:51,162 --> 00:38:52,896 high-energy radiation. 693 00:38:54,598 --> 00:38:56,900 ROWE: As the star embeds in the accretion disk, 694 00:38:57,001 --> 00:38:59,869 a massive flare of radiation erupts, 695 00:38:59,970 --> 00:39:01,271 lighting up the universe. 696 00:39:04,308 --> 00:39:06,076 After this initial burst, 697 00:39:06,177 --> 00:39:08,311 the spinning star debris sends out 698 00:39:08,412 --> 00:39:09,979 a continuous stream of light. 699 00:39:14,418 --> 00:39:17,454 Our telescopes only pick up this radiation 700 00:39:17,555 --> 00:39:20,223 on each rotation of the disk. 701 00:39:20,324 --> 00:39:25,929 It's like seeing the beam from a lighthouse every 130 seconds. 702 00:39:28,299 --> 00:39:32,102 The flashes are the final pulses of a dying star, 703 00:39:33,571 --> 00:39:36,773 and those flashes reveal both the width 704 00:39:36,874 --> 00:39:40,577 and the rotation speed of the supermassive black hole. 705 00:39:43,214 --> 00:39:45,749 We learned that the central massive black hole 706 00:39:45,850 --> 00:39:48,885 is about 300 times wider than the Earth, 707 00:39:48,986 --> 00:39:52,255 but it's rotating every two minutes. 708 00:39:52,356 --> 00:39:55,759 It's rotating at half the speed of light. 709 00:39:55,860 --> 00:40:00,764 ROWE: That's over 300 million miles an hour. 710 00:40:00,865 --> 00:40:04,634 We don't yet know how fast M87 star is spinning, 711 00:40:04,735 --> 00:40:07,771 but we do know the accretion disk rotates it over 712 00:40:07,872 --> 00:40:09,372 two million miles an hour. 713 00:40:10,841 --> 00:40:13,943 This glowing ring, hundreds of light-years wide, 714 00:40:14,044 --> 00:40:16,746 now lies directly ahead of our ship. 715 00:40:16,847 --> 00:40:21,117 It is one of the most awe-inspiring 716 00:40:21,218 --> 00:40:23,753 and deadly places in the universe, 717 00:40:23,854 --> 00:40:26,790 and we are heading straight for it. 718 00:40:40,704 --> 00:40:43,139 ROWE: After our long trek across the galaxy, 719 00:40:43,240 --> 00:40:45,341 we finally face the mighty 720 00:40:45,443 --> 00:40:50,313 supermassive black hole at its center... M87 star. 721 00:40:50,414 --> 00:40:53,283 A dazzling glare confronts us. 722 00:40:53,417 --> 00:40:58,755 This is the accretion disk, a ring of hot gas and dust 723 00:40:58,856 --> 00:41:01,191 spinning at over two million miles an hour. 724 00:41:03,260 --> 00:41:05,795 M87 star's accretion disk 725 00:41:05,896 --> 00:41:08,698 is so bright, the Event Horizon Telescope 726 00:41:08,799 --> 00:41:13,269 photographed it from Earth 55 million light-years away. 727 00:41:15,239 --> 00:41:16,840 So I remember exactly where I was 728 00:41:16,941 --> 00:41:18,675 when that image was released... I was sitting with a bunch of 729 00:41:18,776 --> 00:41:20,543 my colleagues at the Center for Astrophysics, 730 00:41:20,644 --> 00:41:22,745 and we were all watching the press conference live and 731 00:41:22,847 --> 00:41:26,416 just absolutely slack-jawed when that image hit the screen. 732 00:41:26,517 --> 00:41:28,284 OLUSEYI: I was sitting in the airport 733 00:41:28,385 --> 00:41:30,253 when I saw this black hole image, 734 00:41:30,354 --> 00:41:31,788 about to take a flight to New York. 735 00:41:31,889 --> 00:41:34,724 I got so excited that I actually 736 00:41:34,825 --> 00:41:37,360 walked away from my backpack sitting there. 737 00:41:37,461 --> 00:41:40,330 TEGMARK: Seeing that picture, 738 00:41:40,431 --> 00:41:43,800 it really doesn't leave room for doubt. 739 00:41:43,901 --> 00:41:45,235 Black holes are real. 740 00:41:47,004 --> 00:41:49,606 ROWE: The Event Horizon Telescope photo is 741 00:41:49,707 --> 00:41:54,377 the first picture ever taken of a black hole. 742 00:41:54,478 --> 00:41:57,347 The image revealed M87 star 743 00:41:57,448 --> 00:42:00,183 spins in a clockwise direction, 744 00:42:00,284 --> 00:42:04,921 and it's 23.6 billion miles wide. 745 00:42:05,022 --> 00:42:08,191 That's around three million Earths lined up in a row. 746 00:42:09,660 --> 00:42:12,962 The photo also confirmed M87 star's 747 00:42:13,063 --> 00:42:16,432 membership in a very exclusive club... 748 00:42:16,534 --> 00:42:21,638 The 1% of supermassive black holes that actively feed. 749 00:42:23,641 --> 00:42:25,508 The image from the Event Horizon Telescope 750 00:42:25,609 --> 00:42:27,443 tells us that M87 is indeed 751 00:42:27,578 --> 00:42:30,480 actively growing and accreting and eating material 752 00:42:30,581 --> 00:42:34,250 around it... it shows gas swirling around that black hole 753 00:42:34,351 --> 00:42:36,052 on its way to being swallowed. 754 00:42:37,521 --> 00:42:40,590 ROWE: But do all supermassive black holes consume material 755 00:42:40,691 --> 00:42:43,560 in the same way that M87 star does? 756 00:42:44,929 --> 00:42:46,529 Is it possible that different black holes 757 00:42:46,630 --> 00:42:47,664 have different table manners? 758 00:42:47,765 --> 00:42:49,599 Well, it turns out that's really true. 759 00:42:49,700 --> 00:42:52,201 Some are more delicate eaters. 760 00:42:52,303 --> 00:42:56,606 ROWE: In 2018, we discovered a supermassive black hole 761 00:42:56,707 --> 00:43:01,678 250 million light-years from Earth that eats on a schedule. 762 00:43:04,481 --> 00:43:06,649 Now we have this case of a black hole 763 00:43:06,750 --> 00:43:10,486 that looks like it's feeding three times a day. 764 00:43:10,588 --> 00:43:12,889 It's having three square meals a day. 765 00:43:12,990 --> 00:43:15,925 ROWE: Intense bursts of energy pulse out 766 00:43:16,026 --> 00:43:19,596 from galaxy GSN 069. 767 00:43:19,697 --> 00:43:23,666 We see X-ray flares and bursts 768 00:43:23,767 --> 00:43:25,902 coming from the center of this galaxy, 769 00:43:26,003 --> 00:43:30,573 repeating every nine hours, and each burst is associated 770 00:43:30,674 --> 00:43:33,409 with a new feeding event. 771 00:43:33,510 --> 00:43:37,113 ROWE: This supermassive black hole not only 772 00:43:37,214 --> 00:43:38,348 eats on a schedule, 773 00:43:38,449 --> 00:43:41,818 it has a very healthy appetite. 774 00:43:41,919 --> 00:43:46,522 Each one of these meals that this black hole is consuming 775 00:43:46,624 --> 00:43:52,128 is the equivalent of four of our moons in a single bite. 776 00:43:54,898 --> 00:43:57,066 ROWE: So what exactly is this supermassive 777 00:43:57,167 --> 00:43:58,401 black hole consuming? 778 00:44:01,138 --> 00:44:03,973 The most likely contender is a star. 779 00:44:06,844 --> 00:44:10,146 We think that the star has been ripped apart 780 00:44:10,247 --> 00:44:13,349 and spread throughout an accretion disk, and then 781 00:44:13,450 --> 00:44:15,418 slowly over the course of hours, 782 00:44:15,519 --> 00:44:19,756 an instability builds up, and some material falls in. 783 00:44:19,857 --> 00:44:22,025 ROWE: When the infalling material from 784 00:44:22,126 --> 00:44:24,694 the star hit the supermassive black hole, 785 00:44:24,795 --> 00:44:26,663 it triggered a burst of X-rays. 786 00:44:29,633 --> 00:44:32,602 Then, the system stabilized... 787 00:44:32,703 --> 00:44:34,337 until it sparked up again, 788 00:44:36,206 --> 00:44:39,942 creating a nine-hour cycle of bursts of energy. 789 00:44:41,812 --> 00:44:46,949 Then, in 2020 new observations spawned a different theory. 790 00:44:47,051 --> 00:44:50,353 The star wasn't caught on the accretion disk. 791 00:44:50,454 --> 00:44:54,924 The supermassive black hole had instead pulled it into orbit. 792 00:44:56,627 --> 00:45:00,697 Its orbit takes it near that black hole every nine hours, 793 00:45:00,798 --> 00:45:03,733 and every time it encounters the black hole, 794 00:45:03,834 --> 00:45:06,169 some of its material gets sipped off. 795 00:45:09,239 --> 00:45:12,775 ROWE: Eventually, the GSN 069 supermassive 796 00:45:12,876 --> 00:45:15,578 black hole will lose its meal ticket. 797 00:45:17,548 --> 00:45:21,150 But it's luckier than many other supermassive black holes. 798 00:45:22,553 --> 00:45:25,354 Sometimes black holes just take a little nibble on 799 00:45:25,456 --> 00:45:26,889 the surrounding material and just give 800 00:45:26,990 --> 00:45:30,259 a little burp of radiation in response. 801 00:45:32,129 --> 00:45:34,997 ROWE: A black hole burp generates strong 802 00:45:35,099 --> 00:45:38,234 shockwaves that radiate out across the universe. 803 00:45:42,406 --> 00:45:45,374 We detected two of these energy outbursts 804 00:45:45,476 --> 00:45:50,279 in galaxy J1354 1327, 805 00:45:50,380 --> 00:45:53,716 located 800 million light-years away. 806 00:45:55,219 --> 00:45:59,222 The huge burps suggested that the supermassive black hole 807 00:45:59,323 --> 00:46:02,558 at the core of this galaxy was snacking. 808 00:46:04,094 --> 00:46:05,762 It ate a bunch of material one time 809 00:46:05,863 --> 00:46:08,564 that caused a burst of energy flowing outward. 810 00:46:08,665 --> 00:46:11,968 Then it feasted again, and that caused another burp. 811 00:46:13,337 --> 00:46:16,972 ROWE: What caused these separate outbursts? 812 00:46:17,040 --> 00:46:22,245 The belching black hole galaxy has a smaller companion galaxy. 813 00:46:24,348 --> 00:46:27,116 A gas stream links the two galaxies, 814 00:46:27,217 --> 00:46:31,254 supplying an intermittent, on-off food supply. 815 00:46:31,355 --> 00:46:33,256 There's actually a smaller satellite 816 00:46:33,357 --> 00:46:35,458 galaxy going around the bigger galaxy. 817 00:46:35,559 --> 00:46:36,692 The black hole in the middle is 818 00:46:36,794 --> 00:46:40,429 pulling streams of material off this little galaxy. 819 00:46:40,531 --> 00:46:43,633 ROWE: Clumps of material from the companion galaxy 820 00:46:43,734 --> 00:46:47,603 move toward the center of J1354. 821 00:46:47,704 --> 00:46:52,108 Once there, the supermassive black hole grabs them. 822 00:46:52,209 --> 00:46:55,711 Some gas streaming from the neighboring galaxy 823 00:46:55,813 --> 00:46:58,147 reaches the center of 824 00:46:58,248 --> 00:47:01,050 the bigger galaxy when the black hole feeds 825 00:47:01,151 --> 00:47:03,186 and then ejects a jet. 826 00:47:04,688 --> 00:47:07,023 ROWE: When supermassive black holes like the one in 827 00:47:07,124 --> 00:47:11,861 J1354 receive an irregular supply of food, 828 00:47:11,962 --> 00:47:13,863 a cycle is established, 829 00:47:13,964 --> 00:47:18,367 a routine that scientists call feast... 830 00:47:19,837 --> 00:47:21,704 burp... 831 00:47:21,805 --> 00:47:23,039 nap. 832 00:47:25,042 --> 00:47:29,011 The supermassive black hole we're headed towards, M87 star, 833 00:47:29,112 --> 00:47:32,014 doesn't do burp and nap. 834 00:47:32,115 --> 00:47:35,618 It feasts all the time. 835 00:47:35,719 --> 00:47:37,420 Stars come in and get ripped apart, 836 00:47:37,521 --> 00:47:40,323 maybe once every 10,000 or 100,000 years. 837 00:47:40,424 --> 00:47:45,261 Whereas M87 has been shining brightly for millions of years. 838 00:47:45,362 --> 00:47:50,132 It clearly has a supply of gas other than ripped apart stars 839 00:47:50,234 --> 00:47:52,001 that's feeding the accretion disk. 840 00:47:53,704 --> 00:47:56,305 ROWE: This helps explain how M87 star 841 00:47:56,406 --> 00:47:59,375 grew to 6.5 billion solar masses. 842 00:48:03,647 --> 00:48:04,881 But what about the future? 843 00:48:06,550 --> 00:48:09,685 Will this supermassive black hole continue to feast, 844 00:48:12,055 --> 00:48:13,289 or will it starve? 845 00:48:14,658 --> 00:48:17,960 To find out, we have to move even closer, 846 00:48:19,363 --> 00:48:22,365 across the accretion disk, to discover just 847 00:48:22,466 --> 00:48:27,770 how M87 star satisfies its insatiable appetite. 848 00:48:42,119 --> 00:48:47,056 ROWE: Our ship passes over the accretion disk of M87 star, 849 00:48:48,926 --> 00:48:53,429 a blazing ring of gas and dust hundreds of light-years across. 850 00:48:53,530 --> 00:48:58,601 This is the supermassive black hole's grocery store. 851 00:48:58,702 --> 00:49:02,171 Black holes are known for sucking in everything. 852 00:49:02,272 --> 00:49:04,240 But is that really true? 853 00:49:04,341 --> 00:49:05,875 Black holes don't really suck. 854 00:49:05,976 --> 00:49:07,476 It's a popular misconception. 855 00:49:07,577 --> 00:49:09,445 They don't just pull anything in. 856 00:49:09,546 --> 00:49:11,781 In fact, if the sun just instantly turned 857 00:49:11,882 --> 00:49:13,049 into a black hole today, 858 00:49:13,150 --> 00:49:15,518 the Earth would happily continue on in its orbit, 859 00:49:15,619 --> 00:49:17,520 because all that gravity cares about is 860 00:49:17,621 --> 00:49:20,856 how massive and how far away something is. 861 00:49:20,958 --> 00:49:24,060 ROWE: Supermassive black holes like M87 star 862 00:49:24,161 --> 00:49:28,698 are a lot more massive than a regular sun-sized black hole. 863 00:49:28,799 --> 00:49:32,301 This means their gravity is greater and extends much 864 00:49:32,402 --> 00:49:34,103 farther out into the galaxy, 865 00:49:34,204 --> 00:49:38,074 allowing supermassive black holes to attract dust, 866 00:49:38,175 --> 00:49:42,712 gas clouds, and stars from billions of miles away. 867 00:49:42,813 --> 00:49:46,549 But they don't gulp down everything they pull in. 868 00:49:47,617 --> 00:49:49,585 OLUSEYI: The way black holes eat matter 869 00:49:49,686 --> 00:49:52,154 isn't as straightforward as you might imagine. 870 00:49:52,222 --> 00:49:55,157 Earth gains mass every day from 871 00:49:55,258 --> 00:49:56,859 objects falling to it from space. 872 00:49:56,960 --> 00:49:59,996 So you might imagine that matter 873 00:50:00,097 --> 00:50:01,263 falling onto a black hole is 874 00:50:01,365 --> 00:50:03,132 like meteorites falling onto Earth. 875 00:50:03,233 --> 00:50:06,135 They can come in from any direction and land anywhere. 876 00:50:09,072 --> 00:50:11,874 That's not the case around a supermassive black hole. 877 00:50:11,975 --> 00:50:15,511 The most efficient way for a black hole to consume matter 878 00:50:15,612 --> 00:50:20,282 is for it to grow an accretion disk. 879 00:50:20,384 --> 00:50:23,552 ROWE: Accretion disks grow when gas and dust 880 00:50:23,653 --> 00:50:25,955 dragged in by the supermassive black hole's 881 00:50:26,056 --> 00:50:30,693 gravity spirals inward and piles up in a ring. 882 00:50:30,794 --> 00:50:34,330 The ring starts to spin from the combination of gravity, 883 00:50:34,431 --> 00:50:36,999 and the momentum of the gas and dust. 884 00:50:37,100 --> 00:50:40,936 The spinning material flattens into a disc. 885 00:50:41,038 --> 00:50:44,540 The material doesn't fall straight in. 886 00:50:44,641 --> 00:50:46,275 It orbits its way in, 887 00:50:46,376 --> 00:50:51,147 and so it gets accelerated to incredibly fast speeds. 888 00:50:51,248 --> 00:50:53,816 Sometimes, the matter ends up inside the black hole. 889 00:50:53,917 --> 00:50:55,418 Sometimes, the matter ends up getting 890 00:50:55,519 --> 00:50:57,053 kicked away from the black hole. 891 00:50:58,755 --> 00:51:01,223 ROWE: As we traveled through M87, 892 00:51:01,324 --> 00:51:03,726 we witnessed jets and winds 893 00:51:03,827 --> 00:51:07,296 from the supermassive black hole blast this material 894 00:51:07,397 --> 00:51:08,931 out into the galaxy. 895 00:51:09,032 --> 00:51:11,734 But there may be other things that 896 00:51:11,835 --> 00:51:14,203 stop food from entering a black hole. 897 00:51:16,473 --> 00:51:17,740 HOPKINS: The black hole at the center of 898 00:51:17,841 --> 00:51:19,542 our Milky Way galaxy, what we call 899 00:51:19,643 --> 00:51:21,710 Sagittarius A star, appears to 900 00:51:21,812 --> 00:51:25,414 be swallowing material or eating at an incredibly low rate. 901 00:51:27,451 --> 00:51:30,453 ROWE: To discover what's stopping Sagittarius A star, 902 00:51:30,554 --> 00:51:33,155 or Sag A star for short, from feeding, 903 00:51:33,256 --> 00:51:36,826 scientists studied infrared light moving out from 904 00:51:36,927 --> 00:51:38,694 the supermassive black hole. 905 00:51:40,097 --> 00:51:43,766 To do that, they needed to fly high in Earth's atmosphere. 906 00:51:45,435 --> 00:51:48,237 The problem is, water vapor in our atmosphere prevents 907 00:51:48,338 --> 00:51:51,440 the infrared light from space from getting down to the ground. 908 00:51:51,541 --> 00:51:54,310 SOFIA is an infrared telescope built 909 00:51:54,411 --> 00:51:56,946 into the side of an airplane. 910 00:51:57,047 --> 00:52:00,382 As bizarre as that is, it's a very stable platform. 911 00:52:00,484 --> 00:52:03,219 SOFIA can look at these objects emitting infrared 912 00:52:03,320 --> 00:52:05,721 in space and get really good observations of them. 913 00:52:08,391 --> 00:52:11,660 ROWE: SOFIA focuses on the structure of the gas in 914 00:52:11,761 --> 00:52:16,265 the strong magnetic fields at the center of the Milky Way. 915 00:52:16,366 --> 00:52:19,435 This high-resolution telescope can track 916 00:52:19,569 --> 00:52:22,338 the finest grains of dust. 917 00:52:22,439 --> 00:52:25,274 When all the dust grains in a cloud are aligned by 918 00:52:25,375 --> 00:52:26,675 a magnetic field, 919 00:52:26,776 --> 00:52:29,111 they scatter the light coming at them in a certain way, 920 00:52:29,212 --> 00:52:30,813 and we call this polarized light. 921 00:52:30,914 --> 00:52:34,550 The dust grains can actually map out the magnetic field 922 00:52:34,651 --> 00:52:36,685 embedded in that dust cloud. 923 00:52:36,786 --> 00:52:39,421 ROWE: The telescope picked out 924 00:52:39,523 --> 00:52:42,124 the grains arranged in a spiral pattern 925 00:52:42,225 --> 00:52:46,262 and revealed the direction the grains were moving. 926 00:52:46,363 --> 00:52:50,666 This movement reveals why Sag A star is starving. 927 00:52:52,135 --> 00:52:54,970 The magnetic field is channeling them into 928 00:52:55,071 --> 00:52:56,739 orbit around the black hole 929 00:52:56,840 --> 00:52:59,141 instead of allowing them to fall in. 930 00:52:59,242 --> 00:53:01,443 So it's literally keeping those dust grains 931 00:53:01,545 --> 00:53:03,245 away from the black hole. 932 00:53:05,615 --> 00:53:08,551 ROWE: The magnetic fields also pushed clouds of gas, 933 00:53:08,652 --> 00:53:10,853 Sag A star's food source, away from 934 00:53:10,954 --> 00:53:12,521 the supermassive black hole. 935 00:53:14,491 --> 00:53:17,059 This is the situation now, but that's not necessarily 936 00:53:17,160 --> 00:53:19,161 the way things are always going to be. 937 00:53:19,262 --> 00:53:23,465 ROWE: Because magnetic fields can switch directions. 938 00:53:23,567 --> 00:53:26,202 PLAIT: There's a lot of other junk out there, dust and gas 939 00:53:26,303 --> 00:53:28,370 and other stars, that as they get close, 940 00:53:28,471 --> 00:53:31,006 they can change the magnetic field, and that might allow 941 00:53:31,107 --> 00:53:33,075 that dust to fall into the black hole. 942 00:53:34,544 --> 00:53:38,047 ROWE: Magnetic fields changing direction 943 00:53:38,148 --> 00:53:40,683 offers hope for Sag A star. 944 00:53:42,986 --> 00:53:47,489 And magnetic fields could help M87 star feed. 945 00:53:49,693 --> 00:53:52,861 Our mission continues, following this material 946 00:53:52,963 --> 00:53:56,765 plunging down into the supermassive black hole, 947 00:54:02,405 --> 00:54:05,307 We set a course towards the event horizon, 948 00:54:07,210 --> 00:54:11,380 the boundary between the known and the unknown universe, 949 00:54:11,481 --> 00:54:14,650 where the laws of physics no longer apply. 950 00:54:24,995 --> 00:54:27,429 ROWE: Our ship crosses the accretion disk. 951 00:54:30,066 --> 00:54:33,135 Ahead, the absolute darkness of 952 00:54:33,236 --> 00:54:37,473 the supermassive black hole, M87 star. 953 00:54:40,143 --> 00:54:41,844 According to black hole legend, 954 00:54:41,945 --> 00:54:46,682 this is where we meet our end, torn to shreds by gravity. 955 00:54:48,652 --> 00:54:52,454 We have so much wonderful imagery of what would happen if 956 00:54:52,555 --> 00:54:54,823 you were to fall into a black hole from science fiction. 957 00:54:54,924 --> 00:54:57,893 One idea that has caught popular attention 958 00:54:57,994 --> 00:54:59,261 is the notion that 959 00:54:59,362 --> 00:55:02,097 you get spaghettified when you fall into a black hole. 960 00:55:02,198 --> 00:55:04,933 This is me. This is a black hole, 961 00:55:06,403 --> 00:55:09,705 which is pulling stronger on my feet than on my head. 962 00:55:09,806 --> 00:55:12,908 And if this black hole is a little bit heavier 963 00:55:13,009 --> 00:55:16,278 than our sun, this difference 964 00:55:16,379 --> 00:55:17,980 in pull is so strong that I would actually 965 00:55:18,081 --> 00:55:20,616 get spaghettified, torn apart. 966 00:55:24,788 --> 00:55:29,992 ROWE: So will M87 star spaghettify us? 967 00:55:30,093 --> 00:55:32,728 The answer depends on the black hole's mass 968 00:55:32,829 --> 00:55:34,863 and volume ratio. 969 00:55:34,964 --> 00:55:37,232 A stellar mass black hole with the mass 970 00:55:37,334 --> 00:55:41,337 of 14 suns is just 26 miles across. 971 00:55:41,438 --> 00:55:44,840 That's about the size of Oklahoma City. 972 00:55:44,941 --> 00:55:47,343 Such an enormous mass in a small volume 973 00:55:47,444 --> 00:55:51,313 creates a very sharp increase in gravitational tidal forces 974 00:55:51,414 --> 00:55:53,682 as you approach the black hole. 975 00:55:54,751 --> 00:55:55,751 With a small black hole, 976 00:55:55,852 --> 00:55:58,087 the strength of gravity changes so rapidly 977 00:55:58,188 --> 00:56:00,556 with distance that your feet could be pulled 978 00:56:00,657 --> 00:56:03,392 a million times harder than your head. 979 00:56:03,493 --> 00:56:07,196 But with supermassive black holes, that doesn't happen. 980 00:56:07,297 --> 00:56:09,765 ROWE: The mass of a stellar mass black hole 981 00:56:09,866 --> 00:56:11,767 is concentrated in a small area. 982 00:56:11,868 --> 00:56:15,871 A supermassive black hole's mass spreads much wider over 983 00:56:15,972 --> 00:56:18,874 an area a billion times larger, 984 00:56:18,975 --> 00:56:23,212 so its gravity increases gently as you get closer. 985 00:56:23,313 --> 00:56:26,782 This means approaching a supermassive black hole feels 986 00:56:26,883 --> 00:56:28,484 more like walking down a slope 987 00:56:28,585 --> 00:56:32,454 rather than jumping off a cliff, so it won't rip you to shreds. 988 00:56:32,555 --> 00:56:37,025 Supermassive black holes have a bad reputation. 989 00:56:37,127 --> 00:56:40,028 That bad reputation firmly belongs to stellar 990 00:56:40,130 --> 00:56:43,165 mass black holes that rips things to shreds. 991 00:56:43,266 --> 00:56:45,200 TEGMARK: The nice thing about supermassive black holes is 992 00:56:45,301 --> 00:56:48,203 these so-called tidal forces are much weaker, 993 00:56:48,304 --> 00:56:51,373 so I would actually be just fine and be able to take in 994 00:56:51,474 --> 00:56:54,410 this really bizarre scenery around the black hole, 995 00:56:54,511 --> 00:56:58,380 with light from distant objects being bent out of shape. 996 00:56:58,481 --> 00:57:02,818 ROWE: So we can approach M87 star safely. 997 00:57:02,919 --> 00:57:07,122 Once there, we are faced with an awe-inspiring sight. 998 00:57:08,825 --> 00:57:13,028 The supermassive black hole distorts the light around it. 999 00:57:14,197 --> 00:57:15,497 Far away from the black hole, 1000 00:57:15,598 --> 00:57:18,333 that warping isn't very strong, but the closer 1001 00:57:18,435 --> 00:57:20,169 the light gets to the black hole, 1002 00:57:20,270 --> 00:57:23,705 the more severely its path is distorted, and the starlight 1003 00:57:23,807 --> 00:57:27,109 around the black hole becomes really bizarre. 1004 00:57:27,210 --> 00:57:30,479 They get stretched into... Into rings and arcs. 1005 00:57:30,580 --> 00:57:33,682 ROWE: We can even see things hidden behind 1006 00:57:33,783 --> 00:57:35,784 the supermassive black hole. 1007 00:57:35,885 --> 00:57:39,588 I would see, for example, the galaxy behind here looking 1008 00:57:39,689 --> 00:57:41,056 completely warped out of shape, 1009 00:57:41,157 --> 00:57:43,959 because light is bent around the black hole. 1010 00:57:44,060 --> 00:57:47,796 Black holes can even bend light so it comes from my face, 1011 00:57:47,897 --> 00:57:50,799 goes around and comes back on the other side. 1012 00:57:50,900 --> 00:57:53,235 So I could, in principle, use a black hole, 1013 00:57:53,336 --> 00:57:54,970 you know, as a mirror when shaving. 1014 00:57:56,739 --> 00:57:58,507 SUTTER: To really understand 1015 00:57:58,608 --> 00:58:00,576 what's happening around a black hole, 1016 00:58:00,677 --> 00:58:05,647 we need to understand gravity, and the language of gravity is 1017 00:58:05,748 --> 00:58:08,717 the language of spacetime. 1018 00:58:08,818 --> 00:58:12,788 ROWE: Spacetime binds the whole universe together. 1019 00:58:12,889 --> 00:58:15,991 If we could put on special spacetime glasses, 1020 00:58:16,092 --> 00:58:17,526 we'd see stars, 1021 00:58:17,627 --> 00:58:22,698 planets, and galaxies floating on a grid of spacetime. 1022 00:58:22,799 --> 00:58:24,433 These objects have mass, 1023 00:58:24,534 --> 00:58:28,403 and mass distorts and curves spacetime. 1024 00:58:29,906 --> 00:58:32,841 Imagine a trapeze artist with a flat net underneath them. 1025 00:58:32,942 --> 00:58:35,611 When they fall from the trapeze onto that net, 1026 00:58:35,712 --> 00:58:38,347 the net distorts. It forms a dimple 1027 00:58:38,448 --> 00:58:40,482 right where that trapeze artist is. 1028 00:58:40,550 --> 00:58:43,118 The trapeze artist is like a black hole. 1029 00:58:43,219 --> 00:58:45,320 The net is like the fabric of space 1030 00:58:45,421 --> 00:58:48,190 and time distorting because of the mass in it. 1031 00:58:49,659 --> 00:58:51,994 ROWE: This distortion of the spacetime net 1032 00:58:52,095 --> 00:58:55,764 by objects with mass is called gravity. 1033 00:58:55,865 --> 00:58:58,567 The more massive you are, 1034 00:58:58,668 --> 00:59:01,303 the more gravity you have, because 1035 00:59:01,404 --> 00:59:04,006 the more you bend and stretch spacetime. 1036 00:59:04,107 --> 00:59:06,942 So one trapeze artists may bend the net a little bit, 1037 00:59:07,043 --> 00:59:09,378 but a hundred trapeze artists 1038 00:59:09,479 --> 00:59:12,314 will bend that net a lot, and good luck 1039 00:59:12,415 --> 00:59:13,749 trying to walk across it. 1040 00:59:15,785 --> 00:59:17,386 ROWE: M87 star's 1041 00:59:17,487 --> 00:59:20,889 immense gravity bends space, forcing light 1042 00:59:20,990 --> 00:59:22,491 to travel along the curves. 1043 00:59:25,595 --> 00:59:29,197 But what does it do to the other half of the equation, 1044 00:59:29,299 --> 00:59:30,666 time? 1045 00:59:30,767 --> 00:59:34,336 Einstein realized that time actually runs slower 1046 00:59:34,437 --> 00:59:38,574 near a black hole than back on Earth. 1047 00:59:38,675 --> 00:59:42,544 ROWE: It's a process called gravitational time dilation. 1048 00:59:42,645 --> 00:59:44,613 Viewed from a distance, our ship 1049 00:59:44,714 --> 00:59:47,349 appears to move in slow motion. 1050 00:59:47,450 --> 00:59:50,118 But what do we see on board the craft 1051 00:59:50,186 --> 00:59:53,655 as we approach M87 star? 1052 00:59:53,756 --> 00:59:57,192 You would perceive time to proceed on normally. 1053 00:59:57,293 --> 00:59:58,961 You'd look at your watch, and that second hand 1054 00:59:59,062 --> 01:00:01,029 would be going around the dial just like normal. 1055 01:00:01,130 --> 01:00:02,831 But to an outside observer, 1056 01:00:02,932 --> 01:00:06,168 that apparent one minute on your watch could take millions 1057 01:00:06,269 --> 01:00:07,903 to even billions of years. 1058 01:00:08,004 --> 01:00:10,172 If I'm having a Zoom conversation with mommy 1059 01:00:10,273 --> 01:00:13,008 back home, even though I'm feeling 1060 01:00:13,109 --> 01:00:15,210 I'm speaking normally, she would hear me go, 1061 01:00:15,311 --> 01:00:18,180 [exaggeratedly slowly] Hi, mommy. 1062 01:00:18,281 --> 01:00:21,283 [normally] And this is not some sort of illusion. 1063 01:00:21,384 --> 01:00:23,251 My time really is going slower. 1064 01:00:23,353 --> 01:00:25,354 So when I come home, she'd be like, "Hey, Max, you look" 1065 01:00:25,455 --> 01:00:28,390 so good, you look so youthful," and I would actually 1066 01:00:28,491 --> 01:00:32,461 have aged less, because time ran slower over there. 1067 01:00:34,530 --> 01:00:37,499 ROWE: On our final approach into M87 star, 1068 01:00:37,600 --> 01:00:39,935 we reach a crucial milestone. 1069 01:00:40,036 --> 01:00:43,338 We are now at the innermost stable orbit. 1070 01:00:43,439 --> 01:00:46,008 We go any further, we're not getting out ever. 1071 01:00:46,109 --> 01:00:47,442 You have two choices. 1072 01:00:47,543 --> 01:00:52,814 You either escape to safety or you fall into the black hole. 1073 01:00:56,786 --> 01:00:58,086 ROWE: Well, that's easy. 1074 01:00:58,187 --> 01:01:02,090 We detach the probe to approach the black hole alone. 1075 01:01:06,029 --> 01:01:08,864 You can think of the event horizon as being the surface of 1076 01:01:08,965 --> 01:01:11,466 a black hole, but that's a little bit of a misconception. 1077 01:01:11,567 --> 01:01:13,168 There's not actually anything there. 1078 01:01:13,269 --> 01:01:15,137 That's just the distance from the center, 1079 01:01:15,238 --> 01:01:18,740 where the escape velocity is the speed of light. 1080 01:01:20,109 --> 01:01:22,878 ROWE: Because nothing can travel faster than light, 1081 01:01:22,979 --> 01:01:26,515 nothing can escape a black hole. 1082 01:01:26,616 --> 01:01:29,351 Think of the event horizon as a waterfall. 1083 01:01:31,020 --> 01:01:34,589 OLUSEYI: If you imagine the flow of water over a waterfall, 1084 01:01:34,691 --> 01:01:36,358 if you're a fish, you could swim 1085 01:01:36,459 --> 01:01:39,127 up close to that edge and still escape. 1086 01:01:39,228 --> 01:01:40,696 But if you go too far, 1087 01:01:40,797 --> 01:01:43,832 you hit the point of no return, and you're going over. 1088 01:01:46,102 --> 01:01:47,436 ROWE: At the event horizon, 1089 01:01:47,537 --> 01:01:50,372 the water moves faster than the fish can swim 1090 01:01:50,473 --> 01:01:52,774 or our probe can orbit, 1091 01:01:52,875 --> 01:01:56,745 so the waterfall, or gravity, carries them over 1092 01:01:56,846 --> 01:01:59,381 and into the black hole. 1093 01:01:59,482 --> 01:02:01,483 But what about the light around them? 1094 01:02:03,553 --> 01:02:05,120 Imagine that fish that's going over 1095 01:02:05,221 --> 01:02:07,622 the waterfall is carrying a flashlight. 1096 01:02:07,724 --> 01:02:09,658 Say it's an alien fish. 1097 01:02:09,759 --> 01:02:11,660 At a black hole, 1098 01:02:11,761 --> 01:02:15,363 If that fish goes over that event horizon, not only does 1099 01:02:15,465 --> 01:02:17,833 the fish and the flashlight get sucked in, 1100 01:02:17,934 --> 01:02:20,335 but the light of the flashlight get sucked in. 1101 01:02:22,505 --> 01:02:24,673 TREMBLAY: There's nothing that can turn around. 1102 01:02:24,774 --> 01:02:28,009 Light, matter, cows, elephants that passes through 1103 01:02:28,111 --> 01:02:30,512 the event horizon can never come back out. 1104 01:02:30,613 --> 01:02:31,847 It is a one-way ticket. 1105 01:02:31,948 --> 01:02:36,118 ROWE: A one-way ticket through the event horizon. 1106 01:02:36,219 --> 01:02:37,719 Back on the ship, though, we don't 1107 01:02:37,820 --> 01:02:40,655 see the probe entered the supermassive black hole. 1108 01:02:42,125 --> 01:02:44,626 Instead, from our perspective, 1109 01:02:44,727 --> 01:02:51,099 the probe just gets slower and slower and slower and slower. 1110 01:02:53,169 --> 01:02:56,238 ROWE: Until it appears that time simply stops 1111 01:02:56,339 --> 01:02:57,372 for the probe, 1112 01:02:57,473 --> 01:03:01,977 frozen by the enormous gravity of M87 star. 1113 01:03:04,046 --> 01:03:08,049 The probe appears stuck, glued to the surface. 1114 01:03:08,151 --> 01:03:09,751 But that's just our perspective. 1115 01:03:09,852 --> 01:03:13,488 In reality, the probe has already crossed 1116 01:03:13,589 --> 01:03:18,026 the event horizon and is inside the black hole. 1117 01:03:18,127 --> 01:03:20,796 ROWE: If only it was that simple. 1118 01:03:20,897 --> 01:03:24,399 The two major theories that explain how the universe works 1119 01:03:24,500 --> 01:03:27,335 don't work at the event horizon. 1120 01:03:27,403 --> 01:03:30,605 General relativity says the probe enters 1121 01:03:30,706 --> 01:03:32,307 the black hole, 1122 01:03:32,408 --> 01:03:35,944 but quantum mechanics throws up some major hurdles. 1123 01:03:37,313 --> 01:03:40,715 According to some ideas rooted in quantum mechanics, 1124 01:03:40,817 --> 01:03:43,952 there may be something called a firewall, 1125 01:03:44,053 --> 01:03:48,456 a wall of quantum energies that prevents material from 1126 01:03:48,558 --> 01:03:50,959 actually reaching through the event horizon. 1127 01:03:52,695 --> 01:03:54,596 ROWE: The question of what happens 1128 01:03:54,697 --> 01:03:56,331 to anything attempting to cross 1129 01:03:56,432 --> 01:03:59,901 the event horizon has challenged some of the greatest 1130 01:04:00,002 --> 01:04:01,169 minds in physics. 1131 01:04:03,739 --> 01:04:07,442 Will our probe enter the supermassive black hole, 1132 01:04:07,543 --> 01:04:12,080 or will it be burnt to a crisp in a wall of fire? 1133 01:04:27,530 --> 01:04:32,334 Our probe is approaching the event horizon of M87 star, 1134 01:04:32,435 --> 01:04:34,736 but there's a problem. 1135 01:04:34,837 --> 01:04:38,607 The two major theories that explain how the universe works 1136 01:04:38,708 --> 01:04:42,410 don't agree about what happens next. 1137 01:04:42,511 --> 01:04:46,414 One says the probe passes through unscathed. 1138 01:04:46,515 --> 01:04:50,018 The other theory says that's impossible. 1139 01:04:50,119 --> 01:04:52,754 It suggests the probe hits 1140 01:04:52,855 --> 01:04:56,324 an impenetrable barrier called a firewall. 1141 01:04:56,425 --> 01:05:00,295 How can the same event have two different outcomes? 1142 01:05:01,764 --> 01:05:04,599 There's a really interesting puzzle right now, which is 1143 01:05:04,700 --> 01:05:07,969 where general relativity and quantum mechanics meet, 1144 01:05:08,070 --> 01:05:12,040 and it's called the Black Hole Information Paradox. 1145 01:05:12,141 --> 01:05:14,276 What we have is a very schizophrenic situation 1146 01:05:14,377 --> 01:05:16,144 in physics, where we have 1147 01:05:16,245 --> 01:05:18,680 two theories that just don't get along. 1148 01:05:18,781 --> 01:05:21,883 Einstein's theory of gravity explains all the big stuff. 1149 01:05:21,984 --> 01:05:25,220 Quantum field theory explains all the small stuff. 1150 01:05:25,321 --> 01:05:28,089 So which one is right and which one is wrong? 1151 01:05:28,190 --> 01:05:29,457 This is the mystery. 1152 01:05:31,727 --> 01:05:33,161 ROWE: General relativity says, 1153 01:05:33,262 --> 01:05:36,464 in theory, crossing the event horizon is no big deal. 1154 01:05:38,100 --> 01:05:40,168 If you're passing through the event horizon, 1155 01:05:40,269 --> 01:05:43,705 you wouldn't notice anything different. 1156 01:05:43,806 --> 01:05:47,208 MINGARELLI: You can, in fact, cross the event horizon 1157 01:05:47,310 --> 01:05:51,279 of a black hole like M87 star in your spaceship, 1158 01:05:51,380 --> 01:05:54,149 without even knowing that you have, nothing would change, 1159 01:05:54,250 --> 01:05:57,419 you'd just peacefully drift inside. 1160 01:05:59,188 --> 01:06:02,524 ROWE: According to general relativity, our probe crosses 1161 01:06:02,625 --> 01:06:05,293 the event horizon and enters the black hole. 1162 01:06:06,963 --> 01:06:10,365 Quantum mechanics sees it differently. 1163 01:06:10,466 --> 01:06:11,833 When it looks at the probe, 1164 01:06:11,934 --> 01:06:15,036 it doesn't see a robotic spacecraft. 1165 01:06:15,137 --> 01:06:16,271 It sees information. 1166 01:06:17,740 --> 01:06:20,175 THALLER: Everything at a quantum mechanical level 1167 01:06:20,276 --> 01:06:21,443 has information. 1168 01:06:21,544 --> 01:06:23,645 You can think of things like a particle having a charge. 1169 01:06:23,746 --> 01:06:27,015 Particles have spin, angular momentum, and that information, 1170 01:06:27,116 --> 01:06:29,651 as far as we understand, can't be destroyed. 1171 01:06:33,222 --> 01:06:36,124 ROWE: What do we mean by destroyed? 1172 01:06:36,225 --> 01:06:38,393 Well, think of burning a book. 1173 01:06:38,494 --> 01:06:40,695 The words are information. 1174 01:06:40,796 --> 01:06:44,833 As each page burns, the words disappear. 1175 01:06:44,934 --> 01:06:48,336 The information is gone, but not really. 1176 01:06:48,437 --> 01:06:50,038 If you could track every single thing that 1177 01:06:50,139 --> 01:06:52,907 was happening, track each smoke particle, 1178 01:06:53,009 --> 01:06:54,809 put everything back together again, 1179 01:06:54,910 --> 01:06:57,112 in principle, that information is still there. 1180 01:06:58,481 --> 01:07:01,950 ROWE: Because information can't be destroyed, 1181 01:07:02,051 --> 01:07:05,020 the probe's information, even if mangled, 1182 01:07:05,121 --> 01:07:09,057 should be inside the supermassive black hole. 1183 01:07:09,158 --> 01:07:12,961 If the information that fell into a black hole just stayed 1184 01:07:13,062 --> 01:07:15,530 locked inside of a black hole, that'd be fine. 1185 01:07:15,631 --> 01:07:18,199 That doesn't violate any physics. 1186 01:07:18,300 --> 01:07:20,668 ROWE: But Stephen Hawking threw a wrench in the works 1187 01:07:20,770 --> 01:07:23,471 when he theorized that, over time, 1188 01:07:23,572 --> 01:07:29,344 black holes evaporate, slowly shrinking particle by particle, 1189 01:07:29,445 --> 01:07:33,148 emitting heat known as Hawking radiation. 1190 01:07:35,418 --> 01:07:38,887 Hawking radiation itself doesn't carry any 1191 01:07:38,988 --> 01:07:41,423 information out, and Hawking radiation 1192 01:07:41,524 --> 01:07:43,725 eventually destroys a black hole. 1193 01:07:43,826 --> 01:07:48,229 Eventually, the black hole evaporates and disappears. 1194 01:07:48,330 --> 01:07:50,832 ROWE: As the black hole vanishes, so too, 1195 01:07:50,933 --> 01:07:53,568 does information about the probe. 1196 01:07:53,669 --> 01:07:57,505 This is a big problem for quantum mechanics. 1197 01:07:57,606 --> 01:08:00,442 Can black holes really 1198 01:08:00,543 --> 01:08:02,944 destroy information even though 1199 01:08:03,045 --> 01:08:06,347 quantum physics suggests you cannot? 1200 01:08:06,449 --> 01:08:10,051 So is the foundation of quantum mechanics wrong? 1201 01:08:10,152 --> 01:08:13,354 This is the Quantum Information Paradox. 1202 01:08:13,456 --> 01:08:16,858 ROWE: To try to prevent this impossible situation, 1203 01:08:16,959 --> 01:08:19,894 scientists came up with a workaround, 1204 01:08:19,995 --> 01:08:22,997 something that prevents the probe's information 1205 01:08:23,099 --> 01:08:24,933 from ever entering the black hole, 1206 01:08:25,034 --> 01:08:26,868 the firewall. 1207 01:08:28,404 --> 01:08:31,306 Quantum mechanics says that there is this 1208 01:08:31,407 --> 01:08:34,976 quantum fuzz causing there to be 1209 01:08:35,077 --> 01:08:37,145 ridiculously high temperatures literally burning 1210 01:08:37,246 --> 01:08:38,947 you up as soon as you enter. 1211 01:08:40,683 --> 01:08:43,284 ROWE: If the firewall incinerates the probe, 1212 01:08:43,385 --> 01:08:46,354 then its information will stay in the ashes of the ship, 1213 01:08:48,824 --> 01:08:52,260 just like the words from the burning book. 1214 01:08:52,361 --> 01:08:56,731 So which theory is right? 1215 01:08:56,832 --> 01:08:59,334 Does the probe safely enter the black hole? 1216 01:08:59,435 --> 01:09:02,370 Or does the probe burn up? 1217 01:09:04,740 --> 01:09:06,841 I've actually spent an afternoon at Caltech arguing 1218 01:09:06,942 --> 01:09:08,243 with people about whether anything 1219 01:09:08,344 --> 01:09:09,644 falls into a black hole or not, 1220 01:09:09,745 --> 01:09:11,379 and the answer is we don't really know. 1221 01:09:14,150 --> 01:09:15,283 ROWE: To find an answer, 1222 01:09:15,384 --> 01:09:18,586 scientists have come up with some crazy ideas. 1223 01:09:20,422 --> 01:09:22,724 One, called quantum entanglement, 1224 01:09:22,825 --> 01:09:25,960 suggests that the probe is both inside 1225 01:09:26,061 --> 01:09:27,795 and outside the black hole, 1226 01:09:27,897 --> 01:09:32,033 its information carried by particles constantly popping up 1227 01:09:32,134 --> 01:09:34,402 on either side of the event horizon. 1228 01:09:36,539 --> 01:09:38,506 And Stephen Hawking, 1229 01:09:38,607 --> 01:09:41,876 whose original idea that black holes lose information through 1230 01:09:42,011 --> 01:09:44,112 heat, also came up with a solution. 1231 01:09:45,781 --> 01:09:50,118 He suggested that black holes have soft hair. 1232 01:09:50,219 --> 01:09:54,422 Traditional black hole science says they're bald. 1233 01:09:54,523 --> 01:09:56,191 By which we mean that they have 1234 01:09:56,292 --> 01:09:58,326 no features at all except their mass, 1235 01:09:58,427 --> 01:10:00,828 and their charge and their spin that you can measure 1236 01:10:00,930 --> 01:10:02,997 from outside. 1237 01:10:03,098 --> 01:10:06,968 ROWE: Hawking's updated theory says that black hole hair 1238 01:10:07,069 --> 01:10:09,771 is made from ghostly quantum particles, 1239 01:10:09,872 --> 01:10:12,373 which store information. 1240 01:10:12,474 --> 01:10:15,543 Thermal radiation from the evaporating black hole 1241 01:10:15,644 --> 01:10:19,380 carries this information away from the event horizon. 1242 01:10:19,481 --> 01:10:21,516 If Hawking is right, 1243 01:10:21,617 --> 01:10:24,752 the probe's information will eventually escape 1244 01:10:24,853 --> 01:10:26,221 into the universe. 1245 01:10:28,657 --> 01:10:30,425 The concept of black hole hair 1246 01:10:30,526 --> 01:10:35,463 would solve the Black Hole Information Paradox 1247 01:10:35,564 --> 01:10:37,765 if it exists, but we don't know if 1248 01:10:37,866 --> 01:10:40,668 black holes have hair or if they're, you know, bald. 1249 01:10:43,739 --> 01:10:46,941 ROWE: Until we can unite quantum mechanics 1250 01:10:47,042 --> 01:10:49,744 and general relativity at the event horizon, 1251 01:10:49,845 --> 01:10:51,980 the Information Paradox will 1252 01:10:52,081 --> 01:10:55,450 remain a problem for physicists. 1253 01:10:55,551 --> 01:10:57,719 It's one of the most embarrassing problems 1254 01:10:57,820 --> 01:10:59,487 in physics, which is still unsolved. 1255 01:10:59,588 --> 01:11:01,823 I hope one of you who watches this 1256 01:11:01,924 --> 01:11:05,159 will become a physicist and solve it for us, 1257 01:11:05,261 --> 01:11:08,429 because physics is far from done. 1258 01:11:11,934 --> 01:11:14,369 ROWE: The failure to solve the Black Hole 1259 01:11:14,470 --> 01:11:18,072 Information Paradox throws up a major obstacle 1260 01:11:18,173 --> 01:11:21,509 to our understanding of how our universe works. 1261 01:11:23,479 --> 01:11:27,081 This is the point where physics hits a wall. 1262 01:11:27,182 --> 01:11:30,585 While a search for a solution continues, 1263 01:11:30,686 --> 01:11:33,054 let's assume our probe dodges 1264 01:11:33,155 --> 01:11:35,590 its way past the Information Paradox. 1265 01:11:37,259 --> 01:11:41,195 It sails across the event horizon towards one of the most 1266 01:11:41,297 --> 01:11:43,231 violent places in the universe, 1267 01:11:43,332 --> 01:11:46,634 the core of M87 star. 1268 01:11:49,738 --> 01:11:52,473 It's called the singularity, 1269 01:11:52,574 --> 01:11:54,942 and there are no rules. 1270 01:11:55,044 --> 01:11:57,712 Nothing makes sense, 1271 01:11:57,813 --> 01:12:00,315 and nothing escapes. 1272 01:12:14,396 --> 01:12:16,764 ROWE: Our probe has crossed the event horizon. 1273 01:12:16,865 --> 01:12:18,599 It's on a one-way trip to 1274 01:12:18,701 --> 01:12:24,305 the heart of the supermassive black hole M87 star. 1275 01:12:24,406 --> 01:12:26,741 OLUSEYI: Anything that crosses the event horizon 1276 01:12:26,842 --> 01:12:29,477 is not coming out... It's like Vegas. 1277 01:12:29,578 --> 01:12:32,380 What goes in a black hole stays in a black hole. 1278 01:12:34,049 --> 01:12:37,151 ROWE: The probe leaves the physics we understand 1279 01:12:37,252 --> 01:12:40,755 and enters the world of physics we do not. 1280 01:12:42,358 --> 01:12:45,026 This probe is now moving faster than light 1281 01:12:45,127 --> 01:12:48,863 or being carried by space itself faster than light. 1282 01:12:48,964 --> 01:12:51,999 Once you cross the event horizon of a black hole, 1283 01:12:52,101 --> 01:12:56,104 your future lies on the singularity in the center of 1284 01:12:56,205 --> 01:12:58,639 the black hole... there's no escaping the fact that 1285 01:12:58,741 --> 01:13:02,110 you will eventually join the singularity. 1286 01:13:02,211 --> 01:13:04,145 OLUSEYI: The space inside of a black hole 1287 01:13:04,213 --> 01:13:07,115 is like a 3D spinning vortex. 1288 01:13:07,216 --> 01:13:09,917 The space in there is always moving. 1289 01:13:10,018 --> 01:13:13,287 This is the nightmare version of the carousel ride. 1290 01:13:15,124 --> 01:13:19,193 ROWE: The whirling probe hurtles downwards, until it hits 1291 01:13:19,294 --> 01:13:22,964 an even more bizarre region of the black hole... 1292 01:13:23,065 --> 01:13:26,834 the inner event horizon. 1293 01:13:26,935 --> 01:13:29,637 You thought the firewall was bad, 1294 01:13:29,738 --> 01:13:32,907 but that's peanuts compared to the inner event horizon. 1295 01:13:33,008 --> 01:13:35,977 Theoretical physicist Andrew Hamilton believes that all 1296 01:13:36,078 --> 01:13:37,311 light and matter that's fallen 1297 01:13:37,413 --> 01:13:40,748 into a black hole piles up in a tremendous collision at 1298 01:13:40,849 --> 01:13:41,949 this location. 1299 01:13:42,050 --> 01:13:45,920 The inner event horizon would be infinitely violent, 1300 01:13:46,021 --> 01:13:49,557 because it's like the meeting point between two universes. 1301 01:13:52,661 --> 01:13:56,697 ROWE: This meeting point is like water falling and smashing 1302 01:13:56,799 --> 01:13:59,167 into spray, shooting back up 1303 01:13:59,268 --> 01:14:02,069 from the rocks at the base of the falls. 1304 01:14:02,171 --> 01:14:04,472 Inside the supermassive black hole, 1305 01:14:04,573 --> 01:14:09,043 space races in and crashes into rebounding space at 1306 01:14:09,144 --> 01:14:10,311 the inner event horizon. 1307 01:14:11,880 --> 01:14:14,315 SUTTER: This would be a place of infinite energy. 1308 01:14:14,416 --> 01:14:18,786 It's a place where infalling material, into the black hole, 1309 01:14:18,887 --> 01:14:20,655 meets outflowing material. 1310 01:14:20,756 --> 01:14:26,294 ROWE: Everything falling into M87 star smashes together in 1311 01:14:26,395 --> 01:14:28,162 a monumental release of energy. 1312 01:14:28,263 --> 01:14:32,066 This energy has got to go somewhere. 1313 01:14:32,167 --> 01:14:37,839 It's possible that this inner event horizon is so energetic 1314 01:14:37,940 --> 01:14:43,845 that brand-new universes could be born in this space. 1315 01:14:43,946 --> 01:14:47,348 But the question is, how do you actually sort of birth 1316 01:14:47,449 --> 01:14:48,616 a new baby universe? 1317 01:14:49,952 --> 01:14:52,019 ROWE: The energy created at the inner 1318 01:14:52,120 --> 01:14:55,056 event horizon could compress down into 1319 01:14:55,157 --> 01:14:59,460 one tiny speck, which suddenly ignites, 1320 01:15:00,729 --> 01:15:02,597 [explosion blasts] 1321 01:15:02,698 --> 01:15:06,467 Sparking baby universes into life 1322 01:15:08,170 --> 01:15:11,873 in their very own Big Bangs. 1323 01:15:11,974 --> 01:15:15,910 We know that, a long time ago, our own universe was very small, 1324 01:15:16,011 --> 01:15:18,980 very hot, and very dense. 1325 01:15:19,081 --> 01:15:21,916 It's possible that it could have been born in 1326 01:15:22,017 --> 01:15:25,686 the inner event horizon of a spinning black hole. 1327 01:15:25,787 --> 01:15:29,657 This is such a tantalizing 1328 01:15:29,758 --> 01:15:32,126 and very hypothetical idea, 1329 01:15:32,227 --> 01:15:34,929 but if it's correct, 1330 01:15:35,030 --> 01:15:37,331 it gives us insights into the origins 1331 01:15:37,432 --> 01:15:39,433 of our universe itself. 1332 01:15:39,535 --> 01:15:41,836 Do we have strong evidence 1333 01:15:41,937 --> 01:15:45,840 that black holes create baby universes? No. 1334 01:15:45,941 --> 01:15:49,277 Do we have strong evidence that they don't? No. 1335 01:15:51,146 --> 01:15:54,148 ROWE: If the probe survives the inner event horizon, 1336 01:15:54,249 --> 01:15:58,553 it then heads towards the strangest place in the universe, 1337 01:16:00,322 --> 01:16:03,591 the core of a supermassive black hole. 1338 01:16:03,692 --> 01:16:04,725 The singularity. 1339 01:16:06,194 --> 01:16:09,630 As the probe gets closer and closer to the singularity, 1340 01:16:09,731 --> 01:16:12,567 the probe gets further and further away from 1341 01:16:12,668 --> 01:16:14,335 known physics. 1342 01:16:14,436 --> 01:16:16,337 We don't know what the probe 1343 01:16:16,438 --> 01:16:19,106 will encounter when it reaches the singularity. 1344 01:16:19,207 --> 01:16:20,875 We don't know what it will find. 1345 01:16:20,976 --> 01:16:23,444 We don't know what it will experience. 1346 01:16:23,545 --> 01:16:25,146 We don't know. 1347 01:16:27,482 --> 01:16:30,084 ROWE: In other words, there's a lot we don't know. 1348 01:16:30,185 --> 01:16:33,254 Like what exactly is the singularity? 1349 01:16:33,355 --> 01:16:36,557 It's a hard question to answer. 1350 01:16:36,658 --> 01:16:41,062 Traditional science says it's an infinitely tiny point, 1351 01:16:41,129 --> 01:16:44,765 but that's not the case with M87 star. 1352 01:16:44,866 --> 01:16:48,135 What's interesting is that if your black hole is spinning, 1353 01:16:48,236 --> 01:16:52,740 the singularity is not a point, but it's, in fact, a ring. 1354 01:16:52,841 --> 01:16:54,942 ROWE: Physics says the singularity 1355 01:16:55,043 --> 01:16:57,345 is infinitely dense. 1356 01:16:57,446 --> 01:16:59,814 A point of space and time that is... 1357 01:16:59,915 --> 01:17:01,949 It's collapsed as far as it will go, 1358 01:17:02,050 --> 01:17:06,287 it basically has infinite density in zero size. 1359 01:17:06,388 --> 01:17:09,390 ROWE: For many scientists, that's a big problem. 1360 01:17:11,994 --> 01:17:15,529 I do not like singularities. 1361 01:17:15,631 --> 01:17:20,635 I feel that they sound really un-physical. 1362 01:17:20,736 --> 01:17:25,373 The word singularity sounds so intimidating and scientific, 1363 01:17:25,474 --> 01:17:28,376 but it's honestly just our physicists' code word for, 1364 01:17:28,477 --> 01:17:31,145 "Uhh, we have no clue what we're talking about." 1365 01:17:31,246 --> 01:17:35,216 OLUSEYI: Where else in nature do we find infinities? 1366 01:17:35,317 --> 01:17:36,684 We're talking about a region 1367 01:17:36,785 --> 01:17:40,354 that would have infinite density and 1368 01:17:40,455 --> 01:17:43,991 infinitely small volume, basically zero volume. 1369 01:17:44,092 --> 01:17:46,127 How could that exist? I just don't see it. 1370 01:17:46,228 --> 01:17:47,328 We just don't know. 1371 01:17:47,429 --> 01:17:50,097 And frankly, we will never know for sure. 1372 01:17:51,533 --> 01:17:54,769 ROWE: Perhaps the probe breaks up and joins material 1373 01:17:54,870 --> 01:17:59,140 consumed by M87 star over billions of years. 1374 01:18:02,110 --> 01:18:07,214 Compressed down, not just to atoms, but to a sea of energy, 1375 01:18:08,784 --> 01:18:14,522 absorbed into a ring of zero volume and infinite density. 1376 01:18:18,994 --> 01:18:21,595 Or there could be another possibility. 1377 01:18:21,697 --> 01:18:25,933 Maybe the singularity doesn't destroy the probe at all. 1378 01:18:26,034 --> 01:18:29,170 Maybe the probe travels straight on through 1379 01:18:29,271 --> 01:18:32,873 and passes into another universe. 1380 01:18:45,754 --> 01:18:48,489 ROWE: Our voyage to the heart of M87 star 1381 01:18:48,590 --> 01:18:50,091 has been a wild ride. 1382 01:18:52,461 --> 01:18:55,229 We crossed the event horizon and fell towards 1383 01:18:55,330 --> 01:18:57,164 the singularity, 1384 01:18:57,265 --> 01:19:00,568 the core of the supermassive black hole. 1385 01:19:02,971 --> 01:19:05,706 Is this the end of our journey or just the beginning? 1386 01:19:07,075 --> 01:19:09,944 It could be that the singularity isn't 1387 01:19:10,045 --> 01:19:12,480 the end point of the probe's journey. 1388 01:19:12,581 --> 01:19:15,816 It could be that the probe passes through 1389 01:19:15,917 --> 01:19:20,121 the singularity and enters into a new universe. 1390 01:19:21,590 --> 01:19:24,258 ROWE: Our probe has another option, 1391 01:19:24,359 --> 01:19:27,595 an escape route out of M87 star. 1392 01:19:29,297 --> 01:19:31,732 In our universe, we have black holes, 1393 01:19:31,833 --> 01:19:35,536 objects where, if you enter, you can't escape. 1394 01:19:35,637 --> 01:19:38,372 It's also theoretically possible for there to be 1395 01:19:38,473 --> 01:19:39,673 white holes, 1396 01:19:39,775 --> 01:19:44,278 objects that you can't enter, you can only escape from. 1397 01:19:44,379 --> 01:19:48,682 A white hole is basically a black hole running backwards. 1398 01:19:50,552 --> 01:19:53,287 ROWE: Some physicists have theorized that white holes 1399 01:19:53,388 --> 01:19:56,657 may link to the singularities of black holes, 1400 01:19:56,758 --> 01:19:59,393 connected by something called a wormhole. 1401 01:20:02,264 --> 01:20:04,331 TEGMARK: There have been interesting papers written 1402 01:20:04,432 --> 01:20:06,634 suggesting that you could have a wormhole where 1403 01:20:06,735 --> 01:20:09,503 something that falls into a black hole here comes out of 1404 01:20:09,604 --> 01:20:10,838 a white hole somewhere else. 1405 01:20:12,407 --> 01:20:13,674 ROWE: It sounds like a great way 1406 01:20:13,775 --> 01:20:17,845 for the probe to escape certain death, theoretically. 1407 01:20:17,946 --> 01:20:20,347 A wormhole is the bridge 1408 01:20:20,448 --> 01:20:22,316 in spacetime between those two things. 1409 01:20:22,417 --> 01:20:25,019 It's easy to create in mathematics. 1410 01:20:25,120 --> 01:20:29,056 It very well might not exist in real life and will almost 1411 01:20:29,157 --> 01:20:31,258 certainly live out on our entire civilization 1412 01:20:31,359 --> 01:20:33,327 and never know about it. 1413 01:20:33,428 --> 01:20:35,196 ROWE: That's because constructing a bridge 1414 01:20:35,297 --> 01:20:37,598 between a black hole and a white hole 1415 01:20:37,699 --> 01:20:40,267 creates a few issues. 1416 01:20:40,368 --> 01:20:42,503 A, we don't know how to build them for sure. 1417 01:20:42,604 --> 01:20:45,439 B, they might be unstable and collapse on 1418 01:20:45,540 --> 01:20:47,341 themselves immediately, unless you invent... 1419 01:20:47,442 --> 01:20:48,976 Have some new, weird sort of matter that 1420 01:20:49,077 --> 01:20:50,277 can support them. 1421 01:20:50,378 --> 01:20:51,745 OLUSEYI: The problem is that 1422 01:20:51,847 --> 01:20:54,481 it's hard to maintain this bridge open. 1423 01:20:54,583 --> 01:20:56,984 It's not likely that they would ever have 1424 01:20:57,085 --> 01:20:59,720 any practical use because they're just not stable. 1425 01:21:03,325 --> 01:21:06,994 ROWE: But if M87 star does have a stable wormhole linked to 1426 01:21:07,095 --> 01:21:11,031 its singularity, where might our probe end up? 1427 01:21:11,132 --> 01:21:15,803 It could be that this probe's journey doesn't end at 1428 01:21:15,904 --> 01:21:17,071 the singularity, 1429 01:21:17,172 --> 01:21:20,975 and all the information that it carries with it could be 1430 01:21:21,076 --> 01:21:26,313 deposited in some distant corner of our own universe. 1431 01:21:26,414 --> 01:21:29,016 ROWE: Or perhaps in a different universe. 1432 01:21:30,619 --> 01:21:33,988 One idea that sounded like science fiction 1433 01:21:34,089 --> 01:21:37,858 decades ago is actually now considered potential reality, 1434 01:21:37,959 --> 01:21:41,595 and that's the idea of parallel universes. 1435 01:21:41,696 --> 01:21:43,797 If parallel universes exist, 1436 01:21:43,899 --> 01:21:48,168 then some surmise that a black hole could be a gateway 1437 01:21:48,270 --> 01:21:51,071 to a parallel universe. 1438 01:21:51,172 --> 01:21:53,574 ROWE: If there are parallel universes, 1439 01:21:53,675 --> 01:21:56,477 who knows which one our probe may end up in. 1440 01:21:56,578 --> 01:22:00,014 This universe may be just like our own, or 1441 01:22:00,115 --> 01:22:02,983 it might be something completely different. 1442 01:22:04,352 --> 01:22:07,454 We'll never get to find out unless we follow in after it. 1443 01:22:10,525 --> 01:22:12,660 It could all work out just fine, 1444 01:22:12,761 --> 01:22:14,628 and that probe just sails on through 1445 01:22:14,729 --> 01:22:18,432 and gets to explore new adventures. 1446 01:22:18,533 --> 01:22:21,101 We don't know. Only the probe knows. 1447 01:22:26,308 --> 01:22:28,642 ROWE: Supermassive black holes are some of 1448 01:22:28,743 --> 01:22:31,645 the strangest and most fascinating objects in 1449 01:22:31,746 --> 01:22:33,180 the universe. 1450 01:22:33,281 --> 01:22:36,617 Ever since Einstein's Theory of Relativity 1451 01:22:36,718 --> 01:22:39,586 predicted black holes a century ago, 1452 01:22:39,688 --> 01:22:43,290 we've been trying to understand how they work. 1453 01:22:43,391 --> 01:22:48,696 The photograph of M87 star confirmed many theories, 1454 01:22:48,797 --> 01:22:52,333 but there is still much to learn about the birth, 1455 01:22:52,434 --> 01:22:57,037 life, and death of these remarkable objects, 1456 01:22:57,138 --> 01:22:59,773 and even more to leave us fascinated. 1457 01:23:01,743 --> 01:23:03,110 This is the ultimate unknown. 1458 01:23:03,211 --> 01:23:05,245 This is the real Wild West. 1459 01:23:05,347 --> 01:23:09,717 This is the frontier of human knowledge. 1460 01:23:09,818 --> 01:23:12,786 MINGARELLI: I care about supermassive black holes 1461 01:23:12,887 --> 01:23:16,023 first and foremost because they are awesome. 1462 01:23:16,124 --> 01:23:18,892 They stimulate my childhood 1463 01:23:18,994 --> 01:23:21,528 imagination and fascination. 1464 01:23:21,629 --> 01:23:24,865 HOPKINS: Supermassive black holes offer us 1465 01:23:24,966 --> 01:23:28,469 a truly unique window into how the laws of physics work, 1466 01:23:28,570 --> 01:23:32,072 especially the laws of gravity in extreme regimes far beyond 1467 01:23:32,173 --> 01:23:34,408 anything that we can possibly imagine here on Earth. 1468 01:23:35,810 --> 01:23:38,312 THALLER: Supermassive black holes lurk at the heart of 1469 01:23:38,413 --> 01:23:41,548 almost every large galaxy that we know of. 1470 01:23:41,649 --> 01:23:43,217 So in some way, we're just sort of 1471 01:23:43,318 --> 01:23:46,787 all along for the ride with the supermassive black holes. 1472 01:23:46,888 --> 01:23:51,492 If I could make a request for one special favor 1473 01:23:51,593 --> 01:23:53,827 I would get before I die, 1474 01:23:55,397 --> 01:23:58,465 what I would like to do is to get to just spend a few 1475 01:23:58,566 --> 01:24:01,869 hours orbiting the monster black hole in the middle of 1476 01:24:01,970 --> 01:24:04,171 the galaxy... what a way to go.