1 00:00:03,380 --> 00:00:28,800 [Music] 2 00:00:26,320 --> 00:00:30,800 what are you doing right now 3 00:00:28,800 --> 00:00:32,159 if you're watching this video chances 4 00:00:30,800 --> 00:00:34,399 are you'll be sitting down 5 00:00:32,159 --> 00:00:35,600 somewhere and when you're sat down 6 00:00:34,399 --> 00:00:38,879 you're stationary 7 00:00:35,600 --> 00:00:41,200 right wrong well 8 00:00:38,879 --> 00:00:43,600 sort of wrong while you may be 9 00:00:41,200 --> 00:00:46,399 stationary on earth's surface 10 00:00:43,600 --> 00:00:48,000 right now earth itself is moving 11 00:00:46,399 --> 00:00:51,120 hurtling through space 12 00:00:48,000 --> 00:00:52,470 at speeds of around 30 kilometers 13 00:00:51,120 --> 00:00:56,239 per second 14 00:00:52,470 --> 00:00:59,359 [Music] 15 00:00:56,239 --> 00:01:02,000 similarly the sun is also moving at 16 00:00:59,359 --> 00:01:02,960 speeds of around 220 kilometers per 17 00:01:02,000 --> 00:01:05,280 second 18 00:01:02,960 --> 00:01:07,360 dragging our entire solar system with it 19 00:01:05,280 --> 00:01:08,560 as it orbits the galactic tide of the 20 00:01:07,360 --> 00:01:09,840 milky way 21 00:01:08,560 --> 00:01:12,000 [Music] 22 00:01:09,840 --> 00:01:12,960 of course we don't feel either of these 23 00:01:12,000 --> 00:01:14,960 movements 24 00:01:12,960 --> 00:01:16,479 gravity keeps us bolted down for the 25 00:01:14,960 --> 00:01:19,039 ride 26 00:01:16,479 --> 00:01:19,920 but elsewhere in space and given enough 27 00:01:19,039 --> 00:01:22,560 time 28 00:01:19,920 --> 00:01:26,880 everything moves and everything flows 29 00:01:22,560 --> 00:01:29,119 nothing remains stationary in space 30 00:01:26,880 --> 00:01:30,880 but what is it that makes the galaxy 31 00:01:29,119 --> 00:01:33,200 move 32 00:01:30,880 --> 00:01:35,200 well that's going to be our topic today 33 00:01:33,200 --> 00:01:37,200 and it makes for one of astronomy's most 34 00:01:35,200 --> 00:01:39,200 intriguing mysteries 35 00:01:37,200 --> 00:01:41,439 as you are watching this video 36 00:01:39,200 --> 00:01:42,720 everything in our local universe for 37 00:01:41,439 --> 00:01:44,560 millions of light years 38 00:01:42,720 --> 00:01:48,079 including the milky way and the local 39 00:01:44,560 --> 00:01:49,680 group is being dragged through space 40 00:01:48,079 --> 00:01:51,600 pulled through the void towards a 41 00:01:49,680 --> 00:01:53,520 gravitational focal point which we 42 00:01:51,600 --> 00:01:55,680 cannot see 43 00:01:53,520 --> 00:01:56,640 and whatever it is it exerts an 44 00:01:55,680 --> 00:01:59,119 astonishing 45 00:01:56,640 --> 00:02:02,240 almost godlike influence on the vast 46 00:01:59,119 --> 00:02:09,840 swathes of space around it 47 00:02:02,240 --> 00:02:09,840 it is the mystery of the great attractor 48 00:02:14,080 --> 00:02:18,000 the milky way is a vast ancient and 49 00:02:16,800 --> 00:02:20,319 structured collection 50 00:02:18,000 --> 00:02:22,879 of hundreds of billions of stars known 51 00:02:20,319 --> 00:02:25,760 as a galaxy 52 00:02:22,879 --> 00:02:27,360 the universe is teeming with them many 53 00:02:25,760 --> 00:02:29,599 larger and more densely packed with 54 00:02:27,360 --> 00:02:31,920 stars than our own 55 00:02:29,599 --> 00:02:33,840 and when this many stars come together 56 00:02:31,920 --> 00:02:35,360 gravity allows them to work as a 57 00:02:33,840 --> 00:02:37,200 coherent structure 58 00:02:35,360 --> 00:02:39,120 with a much stronger gravitational 59 00:02:37,200 --> 00:02:41,280 influence 60 00:02:39,120 --> 00:02:42,879 galaxies are so incredibly massive that 61 00:02:41,280 --> 00:02:45,040 they can attract one another from 62 00:02:42,879 --> 00:02:46,640 millions of light years across space 63 00:02:45,040 --> 00:02:51,040 sometimes getting close enough to 64 00:02:46,640 --> 00:02:53,680 collide producing new larger galaxies 65 00:02:51,040 --> 00:02:55,599 however the space between galaxies is 66 00:02:53,680 --> 00:02:57,200 significantly more voluminous than the 67 00:02:55,599 --> 00:03:00,080 galaxies themselves 68 00:02:57,200 --> 00:03:01,519 and there is another force at work space 69 00:03:00,080 --> 00:03:04,000 itself is expanding 70 00:03:01,519 --> 00:03:05,280 including the space between galaxies 71 00:03:04,000 --> 00:03:07,360 which pushes them apart 72 00:03:05,280 --> 00:03:09,120 faster than they can attract one another 73 00:03:07,360 --> 00:03:11,840 spreading the contents of the universe 74 00:03:09,120 --> 00:03:14,720 more sparsely 75 00:03:11,840 --> 00:03:16,720 this is known as the hubble flow 76 00:03:14,720 --> 00:03:18,720 galaxies are for the most part 77 00:03:16,720 --> 00:03:21,840 receding away from all other galaxies 78 00:03:18,720 --> 00:03:24,720 uniformly as the universe grows 79 00:03:21,840 --> 00:03:26,959 consequently most galaxies are not close 80 00:03:24,720 --> 00:03:29,040 enough to collide with their neighbours 81 00:03:26,959 --> 00:03:31,200 only very small localized pockets of 82 00:03:29,040 --> 00:03:33,040 space like our local group 83 00:03:31,200 --> 00:03:35,920 will be dense enough to collapse into a 84 00:03:33,040 --> 00:03:38,239 single structure 85 00:03:35,920 --> 00:03:39,280 however while they may not be destined 86 00:03:38,239 --> 00:03:41,360 to collide 87 00:03:39,280 --> 00:03:43,840 dense concentrations of galaxies can 88 00:03:41,360 --> 00:03:45,280 still exert influences on one another 89 00:03:43,840 --> 00:03:47,360 bringing them close enough that the 90 00:03:45,280 --> 00:03:48,079 combined gravitational potential of the 91 00:03:47,360 --> 00:03:50,560 galaxies 92 00:03:48,079 --> 00:03:52,640 attracts more remote galaxies creating 93 00:03:50,560 --> 00:03:53,920 denser concentrations and emptying out 94 00:03:52,640 --> 00:03:57,040 the space in between in a 95 00:03:53,920 --> 00:03:59,200 self-sustaining process 96 00:03:57,040 --> 00:04:01,120 this forms the overarching structure 97 00:03:59,200 --> 00:04:02,080 that stretches across our entire 98 00:04:01,120 --> 00:04:05,920 universe 99 00:04:02,080 --> 00:04:07,920 the cosmic web kind of like a sponge 100 00:04:05,920 --> 00:04:09,280 there are areas of matter which branch 101 00:04:07,920 --> 00:04:12,720 in every direction 102 00:04:09,280 --> 00:04:15,040 and large empty swathes in between 103 00:04:12,720 --> 00:04:17,120 the cosmic web is composed of enormous 104 00:04:15,040 --> 00:04:20,160 walls of interacting galaxies 105 00:04:17,120 --> 00:04:21,759 known as galaxy filaments and these can 106 00:04:20,160 --> 00:04:22,560 contain hundreds of thousands of 107 00:04:21,759 --> 00:04:26,320 galaxies 108 00:04:22,560 --> 00:04:28,160 and span over billions of light years 109 00:04:26,320 --> 00:04:29,759 the galaxies within these filaments 110 00:04:28,160 --> 00:04:30,639 migrate through paths within the 111 00:04:29,759 --> 00:04:33,120 structure 112 00:04:30,639 --> 00:04:35,520 and streams of interacting galaxies flow 113 00:04:33,120 --> 00:04:37,919 converge and diverge like great cosmic 114 00:04:35,520 --> 00:04:40,400 water flows over distances difficult to 115 00:04:37,919 --> 00:04:42,560 comprehend 116 00:04:40,400 --> 00:04:44,720 the individual thread-like components of 117 00:04:42,560 --> 00:04:47,360 a galaxy filament are known as galaxy 118 00:04:44,720 --> 00:04:49,600 clusters and superclusters 119 00:04:47,360 --> 00:04:51,520 smaller groupings of tens hundreds or 120 00:04:49,600 --> 00:04:53,199 perhaps thousands of galaxies 121 00:04:51,520 --> 00:04:55,360 which are more concentrated than the 122 00:04:53,199 --> 00:04:56,960 overall density of the filament 123 00:04:55,360 --> 00:04:59,759 and thus have more substantial 124 00:04:56,960 --> 00:05:01,919 interactions with one another 125 00:04:59,759 --> 00:05:04,000 in truth the lines between clusters 126 00:05:01,919 --> 00:05:04,720 superclusters and filaments are slightly 127 00:05:04,000 --> 00:05:06,639 fuzzy 128 00:05:04,720 --> 00:05:08,960 primarily because we didn't realize that 129 00:05:06,639 --> 00:05:10,000 galaxy structures of filament size could 130 00:05:08,960 --> 00:05:13,120 exist when we coined 131 00:05:10,000 --> 00:05:14,000 the other terms we knew galaxies could 132 00:05:13,120 --> 00:05:15,440 cluster up 133 00:05:14,000 --> 00:05:17,600 but we never thought that they would be 134 00:05:15,440 --> 00:05:18,800 able to interact over billions of light 135 00:05:17,600 --> 00:05:21,840 years 136 00:05:18,800 --> 00:05:21,840 how wrong we were 137 00:05:22,080 --> 00:05:25,840 over the past 40 years we have managed 138 00:05:24,240 --> 00:05:26,960 to build up a comprehensive 139 00:05:25,840 --> 00:05:29,919 three-dimensional map 140 00:05:26,960 --> 00:05:31,360 of intergalactic space and we now know a 141 00:05:29,919 --> 00:05:33,440 considerable amount about our 142 00:05:31,360 --> 00:05:35,680 large-scale surroundings 143 00:05:33,440 --> 00:05:39,440 not bad for a tiny world existing in the 144 00:05:35,680 --> 00:05:41,280 blink of an eye on a galactic time scale 145 00:05:39,440 --> 00:05:43,680 we know that our local group which 146 00:05:41,280 --> 00:05:44,320 contains us andromeda the triangulum 147 00:05:43,680 --> 00:05:46,400 galaxy 148 00:05:44,320 --> 00:05:47,759 and more than 100 other small satellite 149 00:05:46,400 --> 00:05:50,000 dwarf galaxies 150 00:05:47,759 --> 00:05:52,560 is situated in a relatively outlying 151 00:05:50,000 --> 00:05:57,120 region to a cluster of more than 1 152 00:05:52,560 --> 00:05:58,639 300 galaxies known as the virgo cluster 153 00:05:57,120 --> 00:06:00,720 this cluster happens to be the 154 00:05:58,639 --> 00:06:01,600 gravitational core of a much larger 155 00:06:00,720 --> 00:06:03,680 colony 156 00:06:01,600 --> 00:06:04,639 containing over a hundred galaxy groups 157 00:06:03,680 --> 00:06:08,000 like ours 158 00:06:04,639 --> 00:06:08,639 called the virgo supercluster one of 159 00:06:08,000 --> 00:06:10,639 more than an 160 00:06:08,639 --> 00:06:14,880 estimated 10 million galaxy 161 00:06:10,639 --> 00:06:14,880 superclusters in the observable universe 162 00:06:15,120 --> 00:06:19,600 the virgo supercluster extends over an 163 00:06:17,680 --> 00:06:21,919 area of more than 110 164 00:06:19,600 --> 00:06:24,479 million light years and it is thought to 165 00:06:21,919 --> 00:06:25,919 be over 7 thousand times as massive as 166 00:06:24,479 --> 00:06:28,400 the local group 167 00:06:25,919 --> 00:06:31,600 enough to exert a considerable influence 168 00:06:28,400 --> 00:06:33,759 on its intergalactic neighborhood 169 00:06:31,600 --> 00:06:34,639 but the cluster network doesn't end here 170 00:06:33,759 --> 00:06:37,680 either 171 00:06:34,639 --> 00:06:39,440 a groundbreaking study in 2014 172 00:06:37,680 --> 00:06:41,120 published by scientists at the 173 00:06:39,440 --> 00:06:43,440 university of hawaii 174 00:06:41,120 --> 00:06:45,440 revealed that the virgo supercluster is 175 00:06:43,440 --> 00:06:47,759 just one component of an even 176 00:06:45,440 --> 00:06:50,080 greater network of almost unknowable 177 00:06:47,759 --> 00:07:03,280 intricacy and scale 178 00:06:50,080 --> 00:07:06,510 our home galactic supercluster laniakea 179 00:07:03,280 --> 00:07:06,510 [Music] 180 00:07:06,960 --> 00:07:11,360 the lanikia supercluster extends over 181 00:07:09,599 --> 00:07:13,840 half a billion light years across 182 00:07:11,360 --> 00:07:14,840 space and is home to more than a hundred 183 00:07:13,840 --> 00:07:17,840 thousand 184 00:07:14,840 --> 00:07:20,400 galaxies it is so vast 185 00:07:17,840 --> 00:07:22,400 that for a long time we didn't realize 186 00:07:20,400 --> 00:07:24,960 that its constituent superclusters were 187 00:07:22,400 --> 00:07:27,520 connected 188 00:07:24,960 --> 00:07:29,120 laniakia consists of four main galaxy 189 00:07:27,520 --> 00:07:30,560 superclusters 190 00:07:29,120 --> 00:07:32,639 us and the rest of the virgo 191 00:07:30,560 --> 00:07:33,759 supercluster the hydra centaurus 192 00:07:32,639 --> 00:07:36,080 supercluster 193 00:07:33,759 --> 00:07:38,080 the parvo indus supercluster and the 194 00:07:36,080 --> 00:07:39,840 southern supercluster 195 00:07:38,080 --> 00:07:41,280 and despite their enormous cosmic 196 00:07:39,840 --> 00:07:43,520 distances from each other 197 00:07:41,280 --> 00:07:46,720 they interlink to create a plethora of 198 00:07:43,520 --> 00:07:46,720 flows across space 199 00:07:47,120 --> 00:07:50,159 because the lanikia supercluster is so 200 00:07:49,520 --> 00:07:51,520 large 201 00:07:50,159 --> 00:07:53,440 it is not dense enough to be 202 00:07:51,520 --> 00:07:56,080 gravitationally bound 203 00:07:53,440 --> 00:07:57,840 and so as the universe expands instead 204 00:07:56,080 --> 00:07:58,560 of coming together and condensing 205 00:07:57,840 --> 00:08:00,319 further 206 00:07:58,560 --> 00:08:04,319 it should instead get caught up in the 207 00:08:00,319 --> 00:08:06,800 hubble flow dispersing the supercluster 208 00:08:04,319 --> 00:08:07,599 but that's not what we are observing in 209 00:08:06,800 --> 00:08:09,280 practice 210 00:08:07,599 --> 00:08:11,280 or at least not all of what we're 211 00:08:09,280 --> 00:08:13,599 observing 212 00:08:11,280 --> 00:08:15,360 in addition to the universe's expansion 213 00:08:13,599 --> 00:08:18,000 elongating the structure 214 00:08:15,360 --> 00:08:20,319 the entirety of the supercluster appears 215 00:08:18,000 --> 00:08:20,800 to be being attracted to whatever is in 216 00:08:20,319 --> 00:08:24,479 this 217 00:08:20,800 --> 00:08:26,240 area the question is 218 00:08:24,479 --> 00:08:27,840 what could possibly be there that is 219 00:08:26,240 --> 00:08:31,840 powerful enough to unite 220 00:08:27,840 --> 00:08:33,919 galactic superstructures of this size 221 00:08:31,840 --> 00:08:35,279 flows of galaxies aren't uncommon within 222 00:08:33,919 --> 00:08:38,320 galaxy wolves 223 00:08:35,279 --> 00:08:40,479 but this is more than just the flow 224 00:08:38,320 --> 00:08:42,000 there is a gravitational anomaly here 225 00:08:40,479 --> 00:08:44,080 with enormous power 226 00:08:42,000 --> 00:08:46,080 which is anchoring the entire cluster 227 00:08:44,080 --> 00:08:48,160 together and making it move 228 00:08:46,080 --> 00:08:50,399 like a sinkhole to a half a billion 229 00:08:48,160 --> 00:08:52,959 light-year basin 230 00:08:50,399 --> 00:08:55,839 this anomaly is what we mean when we say 231 00:08:52,959 --> 00:08:55,839 the great attractor 232 00:09:02,880 --> 00:09:07,120 the great attractor is the somewhat 233 00:09:04,880 --> 00:09:08,000 ominous name given to the gravitational 234 00:09:07,120 --> 00:09:10,640 focal point 235 00:09:08,000 --> 00:09:11,920 of the lanikia supercluster thought to 236 00:09:10,640 --> 00:09:14,160 lie somewhere around 237 00:09:11,920 --> 00:09:15,760 250 million light years away from the 238 00:09:14,160 --> 00:09:17,680 milky way 239 00:09:15,760 --> 00:09:20,080 and it is attracting the contents of the 240 00:09:17,680 --> 00:09:21,920 cluster towards it 241 00:09:20,080 --> 00:09:23,680 everything for hundreds of millions of 242 00:09:21,920 --> 00:09:26,080 light years is attracted to 243 00:09:23,680 --> 00:09:28,480 and flowing towards this one region 244 00:09:26,080 --> 00:09:30,480 which means one of two things 245 00:09:28,480 --> 00:09:32,160 either there is an unusually high 246 00:09:30,480 --> 00:09:34,240 concentration of mass there 247 00:09:32,160 --> 00:09:35,360 like an ultramassive or dense galaxy 248 00:09:34,240 --> 00:09:37,839 cluster 249 00:09:35,360 --> 00:09:38,560 or perhaps something stranger like a 250 00:09:37,839 --> 00:09:41,279 monstrous 251 00:09:38,560 --> 00:09:43,360 intergalactic black hole or a mysterious 252 00:09:41,279 --> 00:09:46,640 dark force which is counteracting the 253 00:09:43,360 --> 00:09:48,560 universe's expansion 254 00:09:46,640 --> 00:09:50,160 in reality it is likely to be the 255 00:09:48,560 --> 00:09:52,560 product of a dense galaxy 256 00:09:50,160 --> 00:09:54,720 supercluster so massive that it is 257 00:09:52,560 --> 00:09:55,760 influencing the entirety of the virgo 258 00:09:54,720 --> 00:09:58,640 supercluster 259 00:09:55,760 --> 00:09:59,839 as well as the other clusters around it 260 00:09:58,640 --> 00:10:02,800 but whatever it is 261 00:09:59,839 --> 00:10:05,519 there is one fundamental issue we can't 262 00:10:02,800 --> 00:10:07,600 see it 263 00:10:05,519 --> 00:10:09,839 in addition to the nature of the source 264 00:10:07,600 --> 00:10:11,440 itself one of the main things that makes 265 00:10:09,839 --> 00:10:12,320 the greater tractor mystery so 266 00:10:11,440 --> 00:10:16,720 intriguing 267 00:10:12,320 --> 00:10:19,279 yet infuriating is its location 268 00:10:16,720 --> 00:10:21,600 it lies in an area of the sky which is 269 00:10:19,279 --> 00:10:23,200 blocked out by the milky way's galactic 270 00:10:21,600 --> 00:10:25,519 plane from the point of view of the 271 00:10:23,200 --> 00:10:27,440 earth 272 00:10:25,519 --> 00:10:29,360 because of where the solar system lies 273 00:10:27,440 --> 00:10:30,320 in relation to the milky way's galactic 274 00:10:29,360 --> 00:10:32,640 plane 275 00:10:30,320 --> 00:10:34,720 its bright illuminated core and dark 276 00:10:32,640 --> 00:10:37,200 dusty clouds extinguish the light 277 00:10:34,720 --> 00:10:39,279 reaching the galaxy from behind blocking 278 00:10:37,200 --> 00:10:41,760 out approximately one-fifth of our field 279 00:10:39,279 --> 00:10:41,760 of view 280 00:10:41,920 --> 00:10:45,760 this area is known as the zone of 281 00:10:44,079 --> 00:10:47,600 avoidance 282 00:10:45,760 --> 00:10:49,839 where the galaxy's features make it 283 00:10:47,600 --> 00:10:53,200 virtually impossible to see or detect 284 00:10:49,839 --> 00:10:54,720 anything within or beyond it 285 00:10:53,200 --> 00:10:57,120 there's nothing different about the 286 00:10:54,720 --> 00:10:59,200 space behind the zone of avoidance 287 00:10:57,120 --> 00:11:01,410 it is just our position relative to the 288 00:10:59,200 --> 00:11:02,480 galactic core this is the problem 289 00:11:01,410 --> 00:11:05,440 [Music] 290 00:11:02,480 --> 00:11:07,519 in fact in about 100 million years or so 291 00:11:05,440 --> 00:11:08,959 the sun will have orbited the galaxy's 292 00:11:07,519 --> 00:11:10,800 central black hole 293 00:11:08,959 --> 00:11:12,640 taking us to the other side of the milky 294 00:11:10,800 --> 00:11:15,440 way where the backdrop of the zone of 295 00:11:12,640 --> 00:11:17,279 avoidance will be revealed 296 00:11:15,440 --> 00:11:19,440 but that's going to take a very very 297 00:11:17,279 --> 00:11:20,320 long time and so for all intents and 298 00:11:19,440 --> 00:11:23,600 purposes 299 00:11:20,320 --> 00:11:25,519 we are stuck on this side and it just so 300 00:11:23,600 --> 00:11:27,760 happens that the largest gravitational 301 00:11:25,519 --> 00:11:29,279 anomaly in the local universe 302 00:11:27,760 --> 00:11:30,800 which is dragging us and everything 303 00:11:29,279 --> 00:11:32,880 around us towards it 304 00:11:30,800 --> 00:11:34,160 happens to lie behind this obstructed 305 00:11:32,880 --> 00:11:37,040 region 306 00:11:34,160 --> 00:11:39,040 ironic right it certainly makes for a 307 00:11:37,040 --> 00:11:41,360 genuinely interesting and somewhat 308 00:11:39,040 --> 00:11:43,920 unnerving mystery in astronomy 309 00:11:41,360 --> 00:11:46,240 which troubled scientists for around 40 310 00:11:43,920 --> 00:11:46,240 years 311 00:11:46,480 --> 00:11:51,120 the first signs of the greater tractor 312 00:11:48,320 --> 00:11:53,200 were detected in the 1970s when we 313 00:11:51,120 --> 00:11:55,200 realized that the milky way galaxy is 314 00:11:53,200 --> 00:11:56,959 moving through space 315 00:11:55,200 --> 00:11:58,720 back then there was no way to see or 316 00:11:56,959 --> 00:12:00,160 detect anything behind the zone of 317 00:11:58,720 --> 00:12:01,839 avoidance 318 00:12:00,160 --> 00:12:04,000 they didn't have the sophisticated 319 00:12:01,839 --> 00:12:05,279 technology that we have at our disposal 320 00:12:04,000 --> 00:12:07,920 today 321 00:12:05,279 --> 00:12:11,200 and so around 40 degrees of the sky 322 00:12:07,920 --> 00:12:13,760 remained unmapped and unknowable 323 00:12:11,200 --> 00:12:15,920 however as scientists began producing 324 00:12:13,760 --> 00:12:17,600 the first detailed maps of the cosmic 325 00:12:15,920 --> 00:12:19,440 microwave background 326 00:12:17,600 --> 00:12:21,519 that is the primordial microwave 327 00:12:19,440 --> 00:12:23,440 radiation left over from the big bang 328 00:12:21,519 --> 00:12:25,920 which permeates all of space 329 00:12:23,440 --> 00:12:27,519 they discovered what is known as the cmb 330 00:12:25,920 --> 00:12:29,600 dipole 331 00:12:27,519 --> 00:12:32,480 a gradient in the temperature of the sky 332 00:12:29,600 --> 00:12:34,399 from one side to the other 333 00:12:32,480 --> 00:12:36,800 scientists quickly realized that this 334 00:12:34,399 --> 00:12:38,240 disparity is the result of the milky way 335 00:12:36,800 --> 00:12:40,240 moving through space 336 00:12:38,240 --> 00:12:42,639 and the motion in the direction of the 337 00:12:40,240 --> 00:12:43,519 red area compresses the oncoming waves 338 00:12:42,639 --> 00:12:46,320 of radiation 339 00:12:43,519 --> 00:12:49,279 ever so slightly causing that direction 340 00:12:46,320 --> 00:12:51,600 to appear slightly warmer 341 00:12:49,279 --> 00:12:53,120 as we know galaxy's moving through space 342 00:12:51,600 --> 00:12:55,920 is not that unusual 343 00:12:53,120 --> 00:12:58,560 as all galaxies are moving apart largely 344 00:12:55,920 --> 00:13:01,360 in accordance with the hubble flow 345 00:12:58,560 --> 00:13:02,160 but things can affect this flow namely 346 00:13:01,360 --> 00:13:04,839 gravity 347 00:13:02,160 --> 00:13:06,079 and the gravity of objects around a 348 00:13:04,839 --> 00:13:08,079 galaxy 349 00:13:06,079 --> 00:13:09,600 the discrepancy between a galaxy's 350 00:13:08,079 --> 00:13:11,600 actual movement through space 351 00:13:09,600 --> 00:13:13,519 due to gravity when compared with what 352 00:13:11,600 --> 00:13:15,519 one would expect in an expanding 353 00:13:13,519 --> 00:13:16,800 universe is known as its peculiar 354 00:13:15,519 --> 00:13:18,959 velocity 355 00:13:16,800 --> 00:13:20,079 in layman's terms the speed at which a 356 00:13:18,959 --> 00:13:21,839 galaxy moves through 357 00:13:20,079 --> 00:13:24,800 space because of something other than 358 00:13:21,839 --> 00:13:26,639 the universe's expansion 359 00:13:24,800 --> 00:13:29,040 when we tried to measure our peculiar 360 00:13:26,639 --> 00:13:30,320 velocity by tracking the sun relative to 361 00:13:29,040 --> 00:13:32,320 the cmb 362 00:13:30,320 --> 00:13:34,399 we discovered that we are moving towards 363 00:13:32,320 --> 00:13:37,920 the constellation of centaurus at a 364 00:13:34,399 --> 00:13:40,720 speed of about 600 kilometers per second 365 00:13:37,920 --> 00:13:43,360 and this isn't by chance either 366 00:13:40,720 --> 00:13:45,279 something in that area is attracting us 367 00:13:43,360 --> 00:13:48,079 but wherever we were headed it was 368 00:13:45,279 --> 00:13:49,839 situated behind the zone of avoidance 369 00:13:48,079 --> 00:13:51,920 and so the cause of this peculiar 370 00:13:49,839 --> 00:13:56,240 velocity remained a topic of fierce 371 00:13:51,920 --> 00:13:56,240 debate and speculation for many years 372 00:13:58,800 --> 00:14:02,320 initial hypotheses were that they were 373 00:14:00,639 --> 00:14:03,839 just simply more galaxies 374 00:14:02,320 --> 00:14:06,560 in the direction of the zone of 375 00:14:03,839 --> 00:14:08,639 avoidance which we just couldn't see 376 00:14:06,560 --> 00:14:11,040 the milky way's outlying position to the 377 00:14:08,639 --> 00:14:14,079 much denser virgo cluster was also 378 00:14:11,040 --> 00:14:16,320 attributed as a possible cause 379 00:14:14,079 --> 00:14:18,000 however while the virgo cluster could 380 00:14:16,320 --> 00:14:19,839 attract us with its gravity 381 00:14:18,000 --> 00:14:22,800 it is not nearly massive enough to 382 00:14:19,839 --> 00:14:24,959 explain the speed at which we are moving 383 00:14:22,800 --> 00:14:26,639 something considerably more massive was 384 00:14:24,959 --> 00:14:29,120 to blame 385 00:14:26,639 --> 00:14:31,600 and then the mystery got even bigger 386 00:14:29,120 --> 00:14:33,760 quite literally 387 00:14:31,600 --> 00:14:35,120 as redshift surveys began mapping the 388 00:14:33,760 --> 00:14:38,240 universe in 3d 389 00:14:35,120 --> 00:14:40,000 during the 1980s we realized that not 390 00:14:38,240 --> 00:14:42,480 only are we moving towards this 391 00:14:40,000 --> 00:14:44,639 gravitational anomaly in centaurus 392 00:14:42,480 --> 00:14:47,360 but so are the galaxies both above and 393 00:14:44,639 --> 00:14:49,600 below the zone of avoidance 394 00:14:47,360 --> 00:14:52,160 the power of the source was much greater 395 00:14:49,600 --> 00:14:55,360 than once thought 396 00:14:52,160 --> 00:14:58,160 in 1986 it was estimated that the source 397 00:14:55,360 --> 00:15:01,199 of this anomaly lies between 150 million 398 00:14:58,160 --> 00:15:03,440 and 220 million light years away 399 00:15:01,199 --> 00:15:04,720 and two years later an international 400 00:15:03,440 --> 00:15:07,360 team of researchers 401 00:15:04,720 --> 00:15:10,079 led by donald lyndon bell proposed that 402 00:15:07,360 --> 00:15:10,800 the observed motions of 400 elliptical 403 00:15:10,079 --> 00:15:13,120 galaxies 404 00:15:10,800 --> 00:15:15,360 were best fitted by a large bulk flow of 405 00:15:13,120 --> 00:15:17,600 galaxies towards a so-called great 406 00:15:15,360 --> 00:15:19,199 attractor lurking behind the zone of 407 00:15:17,600 --> 00:15:22,880 avoidance 408 00:15:19,199 --> 00:15:24,480 and thus the term was coined 409 00:15:22,880 --> 00:15:27,120 while we didn't know what was causing 410 00:15:24,480 --> 00:15:28,800 the great attractor in order to explain 411 00:15:27,120 --> 00:15:30,320 our peculiar velocity 412 00:15:28,800 --> 00:15:31,920 as well as the motions of so many 413 00:15:30,320 --> 00:15:33,680 galaxies around us 414 00:15:31,920 --> 00:15:36,160 the source of the great attractor was 415 00:15:33,680 --> 00:15:38,160 predicted to be around 10 quintillion 416 00:15:36,160 --> 00:15:41,279 times the mass of the sun 417 00:15:38,160 --> 00:15:43,519 that's 10 million billion suns 418 00:15:41,279 --> 00:15:44,880 equivalent to many thousands of massive 419 00:15:43,519 --> 00:15:46,959 galaxies 420 00:15:44,880 --> 00:15:49,440 and so naturally astronomers were keen 421 00:15:46,959 --> 00:15:51,000 to establish exactly what was lurking in 422 00:15:49,440 --> 00:15:52,959 the dark 423 00:15:51,000 --> 00:15:55,199 [Music] 424 00:15:52,959 --> 00:15:57,040 back when it was first noted our search 425 00:15:55,199 --> 00:15:59,440 for the greater tractor was severely 426 00:15:57,040 --> 00:16:01,519 hindered by the zone of avoidance 427 00:15:59,440 --> 00:16:04,000 but times have changed and technology 428 00:16:01,519 --> 00:16:06,000 has vastly improved 429 00:16:04,000 --> 00:16:08,959 for one thing we're not simply limited 430 00:16:06,000 --> 00:16:10,560 to observing visible light anymore 431 00:16:08,959 --> 00:16:13,040 while the milky way's plane might be 432 00:16:10,560 --> 00:16:15,440 opaque to light that we can see 433 00:16:13,040 --> 00:16:17,680 radio and infrared emissions from galaxy 434 00:16:15,440 --> 00:16:19,920 superclusters outside of the milky way 435 00:16:17,680 --> 00:16:20,800 are capable of penetrating the galaxy's 436 00:16:19,920 --> 00:16:24,000 clouds 437 00:16:20,800 --> 00:16:25,600 even if only slightly this gives us some 438 00:16:24,000 --> 00:16:28,240 idea of what could lie beyond 439 00:16:25,600 --> 00:16:30,000 the avoidance zone albeit a very limited 440 00:16:28,240 --> 00:16:32,320 picture 441 00:16:30,000 --> 00:16:33,839 instead the best means we have of seeing 442 00:16:32,320 --> 00:16:37,519 behind the zone of avoidance 443 00:16:33,839 --> 00:16:39,920 is through x-rays x-rays are another 444 00:16:37,519 --> 00:16:43,279 kind of electromagnetic radiation 445 00:16:39,920 --> 00:16:45,920 like visible light radio and infrared 446 00:16:43,279 --> 00:16:48,079 like the latter x-rays can also pass 447 00:16:45,920 --> 00:16:51,680 through the opaque galactic plane 448 00:16:48,079 --> 00:16:54,079 and are emitted by galaxy superclusters 449 00:16:51,680 --> 00:16:56,320 in addition there are far fewer x-ray 450 00:16:54,079 --> 00:16:58,880 emitting sources in space than there are 451 00:16:56,320 --> 00:17:00,959 sources of infrared and radio waves 452 00:16:58,880 --> 00:17:03,839 making supercluster x-ray emitters 453 00:17:00,959 --> 00:17:07,359 easier to identify 454 00:17:03,839 --> 00:17:08,720 in 1996 using data from the rosat 455 00:17:07,359 --> 00:17:11,119 microwave mission 456 00:17:08,720 --> 00:17:13,599 a team of researchers led by south 457 00:17:11,119 --> 00:17:14,559 african astrophysicist renee krohn 458 00:17:13,599 --> 00:17:16,319 cortez 459 00:17:14,559 --> 00:17:17,919 discovered evidence for a galaxy 460 00:17:16,319 --> 00:17:20,079 supercluster within the zone of 461 00:17:17,919 --> 00:17:21,439 avoidance that had previously evaded 462 00:17:20,079 --> 00:17:23,119 detection 463 00:17:21,439 --> 00:17:25,199 now thought to be a key galactic 464 00:17:23,119 --> 00:17:27,280 concentration at the heart of the great 465 00:17:25,199 --> 00:17:29,280 attractor 466 00:17:27,280 --> 00:17:30,880 while the cluster had been undetectable 467 00:17:29,280 --> 00:17:32,720 through visible light within an 468 00:17:30,880 --> 00:17:35,600 area spanning just two degrees of the 469 00:17:32,720 --> 00:17:38,240 sky by plotting the x-ray sources 470 00:17:35,600 --> 00:17:40,720 identified by rosat onto the area 471 00:17:38,240 --> 00:17:42,160 a significant galaxy cluster is revealed 472 00:17:40,720 --> 00:17:46,240 in the backdrop 473 00:17:42,160 --> 00:17:48,640 known as arbul 3627 also known as the 474 00:17:46,240 --> 00:17:51,600 norma cluster 475 00:17:48,640 --> 00:17:53,679 the norma cluster lies around 220 476 00:17:51,600 --> 00:17:55,440 million light years away from the earth 477 00:17:53,679 --> 00:17:58,559 and is thought to be very close to the 478 00:17:55,440 --> 00:18:00,400 proposed heart of the greater tractor 479 00:17:58,559 --> 00:18:02,880 and it is thought to have a mass in the 480 00:18:00,400 --> 00:18:04,480 region of one quadrillion times that of 481 00:18:02,880 --> 00:18:06,480 our sun 482 00:18:04,480 --> 00:18:08,799 and so we realized that the great 483 00:18:06,480 --> 00:18:09,120 attractor was probably a supercluster 484 00:18:08,799 --> 00:18:11,550 with 485 00:18:09,120 --> 00:18:12,960 arbol 3627 near its core 486 00:18:11,550 --> 00:18:15,280 [Music] 487 00:18:12,960 --> 00:18:17,360 however even at the time the team knew 488 00:18:15,280 --> 00:18:19,760 that the norma cluster probably didn't 489 00:18:17,360 --> 00:18:21,840 account for the full picture 490 00:18:19,760 --> 00:18:23,360 while it is massive it didn't seem 491 00:18:21,840 --> 00:18:26,320 massive enough to account for the 492 00:18:23,360 --> 00:18:28,960 peculiar velocity of the milky way 493 00:18:26,320 --> 00:18:30,960 something else must be at work but 494 00:18:28,960 --> 00:18:32,320 unfortunately we were still limited in 495 00:18:30,960 --> 00:18:33,840 what we could observe due to the 496 00:18:32,320 --> 00:18:36,480 obscured zone 497 00:18:33,840 --> 00:18:39,919 and so the mystery remained inconclusive 498 00:18:36,480 --> 00:18:39,919 heading into the new millennium 499 00:18:41,120 --> 00:18:44,240 while many scientists agree that the 500 00:18:43,200 --> 00:18:46,000 great attractor 501 00:18:44,240 --> 00:18:47,280 is the result of a dense galaxy 502 00:18:46,000 --> 00:18:49,039 concentration 503 00:18:47,280 --> 00:18:51,280 i should take this opportunity to 504 00:18:49,039 --> 00:18:53,440 mention that it is by no means the only 505 00:18:51,280 --> 00:18:55,520 theory 506 00:18:53,440 --> 00:18:58,160 there were those who refuted the idea of 507 00:18:55,520 --> 00:19:00,160 a galaxy supercluster being responsible 508 00:18:58,160 --> 00:19:01,840 due to the incomparable scale of its 509 00:19:00,160 --> 00:19:04,320 influence when compared with other 510 00:19:01,840 --> 00:19:07,280 cosmic structures 511 00:19:04,320 --> 00:19:09,520 in fact because the universe's expansion 512 00:19:07,280 --> 00:19:12,240 is thought to be powered and accelerated 513 00:19:09,520 --> 00:19:14,160 by a phenomenon known as dark energy 514 00:19:12,240 --> 00:19:15,600 there are those who suggest that only 515 00:19:14,160 --> 00:19:18,799 something equally as 516 00:19:15,600 --> 00:19:21,280 dark would be sufficient to overcome it 517 00:19:18,799 --> 00:19:24,320 dark in the sense that it is unknown and 518 00:19:21,280 --> 00:19:26,080 beyond our realm of understanding 519 00:19:24,320 --> 00:19:28,160 this brings us onto a branch of 520 00:19:26,080 --> 00:19:29,520 alternate explanations for the great 521 00:19:28,160 --> 00:19:31,440 attractor 522 00:19:29,520 --> 00:19:33,440 the idea that instead of a galaxy 523 00:19:31,440 --> 00:19:35,760 supercluster attracting us 524 00:19:33,440 --> 00:19:37,440 a mysterious undiscovered force is 525 00:19:35,760 --> 00:19:38,720 responsible for the bulk flows of 526 00:19:37,440 --> 00:19:41,760 galaxies that we see 527 00:19:38,720 --> 00:19:45,520 in lanikia like enormous jet stream air 528 00:19:41,760 --> 00:19:48,720 currents in the vacuum of space 529 00:19:45,520 --> 00:19:51,200 this idea is called dark flow and it is 530 00:19:48,720 --> 00:19:53,120 defined as a non-random component 531 00:19:51,200 --> 00:19:55,200 of the universe's expansion which 532 00:19:53,120 --> 00:19:57,440 deviates from the hubble flow 533 00:19:55,200 --> 00:19:58,320 causing galaxies to stream towards a 534 00:19:57,440 --> 00:20:00,400 single point 535 00:19:58,320 --> 00:20:02,400 like the greater tractor rather than 536 00:20:00,400 --> 00:20:05,039 receding away from one another as one 537 00:20:02,400 --> 00:20:06,799 might expect 538 00:20:05,039 --> 00:20:08,720 if this is the case and there is 539 00:20:06,799 --> 00:20:09,679 something darker at play than we yet 540 00:20:08,720 --> 00:20:11,440 realize 541 00:20:09,679 --> 00:20:14,000 then perhaps we might be able to see 542 00:20:11,440 --> 00:20:15,200 evidence of a gigantic flow mechanism by 543 00:20:14,000 --> 00:20:16,880 searching for something 544 00:20:15,200 --> 00:20:19,440 at the opposite end of the great 545 00:20:16,880 --> 00:20:22,159 attractor a great repeller 546 00:20:19,440 --> 00:20:23,280 if you would while that might sound a 547 00:20:22,159 --> 00:20:26,799 bit outlandish 548 00:20:23,280 --> 00:20:27,919 in 2017 we did see something just like 549 00:20:26,799 --> 00:20:32,240 this 550 00:20:27,919 --> 00:20:34,080 the dipole repeller just as all galaxies 551 00:20:32,240 --> 00:20:36,240 in the lanikia supercluster 552 00:20:34,080 --> 00:20:38,480 are flowing towards the great attractor 553 00:20:36,240 --> 00:20:40,240 they all seem to be flowing away from an 554 00:20:38,480 --> 00:20:41,600 area on the opposite end of the 555 00:20:40,240 --> 00:20:43,520 supercluster 556 00:20:41,600 --> 00:20:45,679 a region which appears to be pushing its 557 00:20:43,520 --> 00:20:47,679 galaxies outwards and setting them on 558 00:20:45,679 --> 00:20:49,520 their galactic paths towards the greater 559 00:20:47,679 --> 00:20:51,360 tractor 560 00:20:49,520 --> 00:20:53,440 perhaps the greater tractor and the 561 00:20:51,360 --> 00:20:54,480 dipole repeller are part of some dark 562 00:20:53,440 --> 00:20:56,640 cosmic system 563 00:20:54,480 --> 00:20:59,600 capable of overcoming the effects of the 564 00:20:56,640 --> 00:21:02,000 universe's expansion 565 00:20:59,600 --> 00:21:04,000 however while the dipole repeller may 566 00:21:02,000 --> 00:21:05,600 seem anomalous and indicative of 567 00:21:04,000 --> 00:21:07,520 something more spooky 568 00:21:05,600 --> 00:21:10,080 dark flow certainly doesn't need to 569 00:21:07,520 --> 00:21:12,480 exist to explain it 570 00:21:10,080 --> 00:21:14,080 in fact the dipole repeller probably 571 00:21:12,480 --> 00:21:16,720 isn't even an anomaly 572 00:21:14,080 --> 00:21:19,200 but rather a natural byproduct of galaxy 573 00:21:16,720 --> 00:21:21,360 cluster formation 574 00:21:19,200 --> 00:21:23,280 as the compound process of galaxies 575 00:21:21,360 --> 00:21:25,440 gathering and attracting more galaxies 576 00:21:23,280 --> 00:21:27,440 creates denser galaxy clusters 577 00:21:25,440 --> 00:21:29,200 this process in turn empties out the 578 00:21:27,440 --> 00:21:31,200 space around the cluster 579 00:21:29,200 --> 00:21:33,280 creating voids between clumps of 580 00:21:31,200 --> 00:21:35,440 galaxies 581 00:21:33,280 --> 00:21:37,760 the more populous and massive the galaxy 582 00:21:35,440 --> 00:21:38,400 cluster the more voids will form around 583 00:21:37,760 --> 00:21:40,720 it 584 00:21:38,400 --> 00:21:43,520 as areas are raided for their galaxies 585 00:21:40,720 --> 00:21:45,760 to feed the structure 586 00:21:43,520 --> 00:21:47,600 and so while it may seem like galaxies 587 00:21:45,760 --> 00:21:48,559 are being pushed away from the dipole 588 00:21:47,600 --> 00:21:51,360 repeller 589 00:21:48,559 --> 00:21:53,760 in reality nothing is pushing them only 590 00:21:51,360 --> 00:21:55,840 the pulling force of gravity 591 00:21:53,760 --> 00:21:57,600 and the dipole repeller is merely just 592 00:21:55,840 --> 00:21:58,960 an area which has had its galaxies 593 00:21:57,600 --> 00:22:01,600 emptied out by massive 594 00:21:58,960 --> 00:22:05,280 influences which holds the appearance of 595 00:22:01,600 --> 00:22:05,280 a so-called virtual repeller 596 00:22:05,440 --> 00:22:09,360 so then if there is no dark force at 597 00:22:07,440 --> 00:22:12,000 work to produce these flows 598 00:22:09,360 --> 00:22:14,080 then what is causing us to move so fast 599 00:22:12,000 --> 00:22:16,960 if not the clusters in the region of the 600 00:22:14,080 --> 00:22:16,960 greater tractor 601 00:22:17,600 --> 00:22:22,000 in the early 2000s a study called the 602 00:22:20,159 --> 00:22:22,880 clusters in the zone of avoidance 603 00:22:22,000 --> 00:22:25,840 project 604 00:22:22,880 --> 00:22:27,919 or caesar selected x-ray signatures 605 00:22:25,840 --> 00:22:29,520 recorded by the rosat mission for 606 00:22:27,919 --> 00:22:31,600 follow-up and investigation 607 00:22:29,520 --> 00:22:34,000 with newer more effective x-ray 608 00:22:31,600 --> 00:22:36,080 technology 609 00:22:34,000 --> 00:22:37,760 the aim of the project was to map this 610 00:22:36,080 --> 00:22:39,679 final portion of the sky 611 00:22:37,760 --> 00:22:41,760 in the zone of avoidance that remained 612 00:22:39,679 --> 00:22:44,000 uncharted for so many years 613 00:22:41,760 --> 00:22:46,159 and also to focus in on what makes the 614 00:22:44,000 --> 00:22:49,760 region of the great attractor so 615 00:22:46,159 --> 00:22:52,559 great in doing so 616 00:22:49,760 --> 00:22:54,960 they identified over 200 previously 617 00:22:52,559 --> 00:22:56,320 undiscovered galaxy clusters in galactic 618 00:22:54,960 --> 00:22:58,320 no-man's land 619 00:22:56,320 --> 00:23:00,720 including in the proposed region of the 620 00:22:58,320 --> 00:23:03,360 great attractor 621 00:23:00,720 --> 00:23:05,440 however these clusters were found to be 622 00:23:03,360 --> 00:23:07,200 significantly less massive than what was 623 00:23:05,440 --> 00:23:08,960 once predicted to account for our 624 00:23:07,200 --> 00:23:11,120 peculiar velocity 625 00:23:08,960 --> 00:23:12,720 only a tenth of the proposed mass in 626 00:23:11,120 --> 00:23:15,200 fact 627 00:23:12,720 --> 00:23:18,320 in reality the great attractor is not 628 00:23:15,200 --> 00:23:20,000 nearly as great as we once thought 629 00:23:18,320 --> 00:23:22,159 while it is the focal point of the 630 00:23:20,000 --> 00:23:23,440 lanikia supercluster which is dragging 631 00:23:22,159 --> 00:23:27,280 us towards it 632 00:23:23,440 --> 00:23:29,919 it is not the only thing influencing us 633 00:23:27,280 --> 00:23:32,240 instead the caesar survey revealed a 634 00:23:29,919 --> 00:23:34,559 substantial concentration of galaxies 635 00:23:32,240 --> 00:23:38,320 much further beyond the greater tractor 636 00:23:34,559 --> 00:23:38,320 near the shapley supercluster 637 00:23:42,159 --> 00:23:46,000 the shapley supercluster is one of the 638 00:23:44,159 --> 00:23:49,120 most studied of its kind 639 00:23:46,000 --> 00:23:50,000 with its 25 constituent galaxy clusters 640 00:23:49,120 --> 00:23:55,200 marked here in 641 00:23:50,000 --> 00:23:57,200 blue it is situated around 650 million 642 00:23:55,200 --> 00:23:59,679 light years away from the milky way 643 00:23:57,200 --> 00:24:01,279 and while it was discovered in the 1930s 644 00:23:59,679 --> 00:24:03,039 by harlow shapley 645 00:24:01,279 --> 00:24:05,360 it didn't become a topic of interest 646 00:24:03,039 --> 00:24:07,600 until the late 90s and the advent of 647 00:24:05,360 --> 00:24:11,039 better technology 648 00:24:07,600 --> 00:24:13,760 but from 1997 until 2001 649 00:24:11,039 --> 00:24:15,600 no less than 40 scientific papers were 650 00:24:13,760 --> 00:24:18,640 published on the cluster 651 00:24:15,600 --> 00:24:20,799 and in 2005 caesar discovered a 652 00:24:18,640 --> 00:24:23,600 concentrated region of galaxies in the 653 00:24:20,799 --> 00:24:26,880 vicinity of the shapley supercluster 654 00:24:23,600 --> 00:24:29,200 nicknamed the shapley attractor 655 00:24:26,880 --> 00:24:32,320 an even greater a more massive galactic 656 00:24:29,200 --> 00:24:34,400 over density than the great attractor 657 00:24:32,320 --> 00:24:36,640 lying around half a billion light years 658 00:24:34,400 --> 00:24:39,279 away 659 00:24:36,640 --> 00:24:40,799 in total shapley is home to more than 8 660 00:24:39,279 --> 00:24:42,960 000 galaxies 661 00:24:40,799 --> 00:24:45,520 and has a mass equivalent to about 10 662 00:24:42,960 --> 00:24:47,200 000 times that of the milky way 663 00:24:45,520 --> 00:24:48,960 four times greater than the mass 664 00:24:47,200 --> 00:24:51,120 observed in the region of the greater 665 00:24:48,960 --> 00:24:52,720 tractor by the same project 666 00:24:51,120 --> 00:24:55,200 and so it is now believed that this 667 00:24:52,720 --> 00:24:57,279 supercluster is contributing the lion's 668 00:24:55,200 --> 00:25:00,720 share of influence responsible for the 669 00:24:57,279 --> 00:25:02,799 milky way's peculiar velocity 670 00:25:00,720 --> 00:25:05,120 while everything in our supercluster is 671 00:25:02,799 --> 00:25:07,279 flowing towards the greater tractor 672 00:25:05,120 --> 00:25:10,880 the greater tractor itself is being 673 00:25:07,279 --> 00:25:12,880 pulled towards the shapley supercluster 674 00:25:10,880 --> 00:25:14,080 yes the reason that the milky way is 675 00:25:12,880 --> 00:25:16,320 being pulled so quickly 676 00:25:14,080 --> 00:25:18,640 towards centaurus is due to the fact 677 00:25:16,320 --> 00:25:19,600 that it is not just the greater tractor 678 00:25:18,640 --> 00:25:22,799 attracting us 679 00:25:19,600 --> 00:25:24,480 in that direction our peculiar velocity 680 00:25:22,799 --> 00:25:26,320 is likely the result of a compound 681 00:25:24,480 --> 00:25:28,480 effect with the greater tractor 682 00:25:26,320 --> 00:25:31,120 responsible for about 44 683 00:25:28,480 --> 00:25:33,520 of the motion being closer to us and the 684 00:25:31,120 --> 00:25:35,600 remaining 56 percent of our velocity 685 00:25:33,520 --> 00:25:37,520 owes to the much more massive and remote 686 00:25:35,600 --> 00:25:39,520 shapley supercluster 687 00:25:37,520 --> 00:25:41,039 which is dragging the greater tractor 688 00:25:39,520 --> 00:25:42,000 and thus the galaxies in our 689 00:25:41,039 --> 00:25:45,360 supercluster 690 00:25:42,000 --> 00:25:47,200 along with it and so it was 691 00:25:45,360 --> 00:25:49,760 with this crucial piece of the puzzle 692 00:25:47,200 --> 00:25:52,000 that astronomers at hawaii university 693 00:25:49,760 --> 00:25:53,600 were able to redefine the boundaries of 694 00:25:52,000 --> 00:25:55,360 our local supercluster 695 00:25:53,600 --> 00:25:56,960 using the great attractor and the 696 00:25:55,360 --> 00:25:57,919 effects of the more remote shapley 697 00:25:56,960 --> 00:26:00,320 attractor 698 00:25:57,919 --> 00:26:04,080 to map our galactic colony and define 699 00:26:00,320 --> 00:26:04,080 the lanikia supercluster 700 00:26:05,120 --> 00:26:10,159 but there was one more piece of the 701 00:26:06,720 --> 00:26:11,679 mystery which we had yet to discover 702 00:26:10,159 --> 00:26:14,320 when the shapley attractor was 703 00:26:11,679 --> 00:26:15,520 identified astronomers speculated that 704 00:26:14,320 --> 00:26:17,919 there may be another 705 00:26:15,520 --> 00:26:19,760 even more remote galaxy supercluster 706 00:26:17,919 --> 00:26:23,039 which is also contributing to our 707 00:26:19,760 --> 00:26:26,159 perceived movement across space 708 00:26:23,039 --> 00:26:27,840 and only five years ago did renee cron 709 00:26:26,159 --> 00:26:29,600 cortez and her team 710 00:26:27,840 --> 00:26:31,840 the same team that discovered the norma 711 00:26:29,600 --> 00:26:33,679 cluster some 20 years prior 712 00:26:31,840 --> 00:26:37,039 finally solved the mystery that they had 713 00:26:33,679 --> 00:26:40,640 been studying for many decades 714 00:26:37,039 --> 00:26:42,480 in 2016 kron courtferg and her team 715 00:26:40,640 --> 00:26:44,559 announced the discovery of a new 716 00:26:42,480 --> 00:26:45,600 supercluster in the zone of avoidance 717 00:26:44,559 --> 00:26:47,520 region 718 00:26:45,600 --> 00:26:49,760 even further beyond than the shapley 719 00:26:47,520 --> 00:26:52,000 supercluster 720 00:26:49,760 --> 00:26:54,080 using data from the anglo-australian 721 00:26:52,000 --> 00:26:54,960 telescope and the southern african large 722 00:26:54,080 --> 00:26:57,760 telescope 723 00:26:54,960 --> 00:27:00,240 they identified a region of over-density 724 00:26:57,760 --> 00:27:03,679 consistent with a galactic supercluster 725 00:27:00,240 --> 00:27:06,400 around 800 million light years away 726 00:27:03,679 --> 00:27:07,600 this galaxy cluster termed the velar 727 00:27:06,400 --> 00:27:10,320 supercluster 728 00:27:07,600 --> 00:27:11,600 is the final piece of the puzzle thought 729 00:27:10,320 --> 00:27:13,919 to contribute at least 730 00:27:11,600 --> 00:27:16,000 50 kilometers a second to our peculiar 731 00:27:13,919 --> 00:27:18,240 velocity 732 00:27:16,000 --> 00:27:20,480 with the influence of the norma cluster 733 00:27:18,240 --> 00:27:22,480 the shapley attractor and a little help 734 00:27:20,480 --> 00:27:24,159 from the velar supercluster 735 00:27:22,480 --> 00:27:26,080 the observed effects of the great 736 00:27:24,159 --> 00:27:26,720 attractor that were noticed all those 737 00:27:26,080 --> 00:27:34,630 years ago 738 00:27:26,720 --> 00:27:52,069 can finally be explained 739 00:27:34,630 --> 00:27:52,069 [Music] 740 00:27:53,360 --> 00:27:58,080 so with all these things considered what 741 00:27:55,440 --> 00:28:00,080 will be the outcome for us 742 00:27:58,080 --> 00:28:01,360 will we be pulled into the center of the 743 00:28:00,080 --> 00:28:02,720 greater tractor 744 00:28:01,360 --> 00:28:04,880 will the rest of the lenny kia 745 00:28:02,720 --> 00:28:08,159 supercluster will it destroy 746 00:28:04,880 --> 00:28:11,679 our galaxy in the process 747 00:28:08,159 --> 00:28:13,279 well the answer is almost certainly no 748 00:28:11,679 --> 00:28:15,600 while we are being lugged in the 749 00:28:13,279 --> 00:28:17,440 direction of these superclusters against 750 00:28:15,600 --> 00:28:19,440 the expansion of the universe 751 00:28:17,440 --> 00:28:21,760 the force that drives the hubble flow is 752 00:28:19,440 --> 00:28:23,440 accelerating 753 00:28:21,760 --> 00:28:25,919 we will never reach the shapley 754 00:28:23,440 --> 00:28:27,360 supercluster or even the greater tractor 755 00:28:25,919 --> 00:28:29,440 for that matter 756 00:28:27,360 --> 00:28:31,679 as before long dark energy will have 757 00:28:29,440 --> 00:28:33,600 inflated the universe so aggressively 758 00:28:31,679 --> 00:28:35,440 that the influences of the great and 759 00:28:33,600 --> 00:28:38,159 shapley attractors will no longer be 760 00:28:35,440 --> 00:28:40,159 able to overcome it 761 00:28:38,159 --> 00:28:42,480 though we are moving towards centaurus 762 00:28:40,159 --> 00:28:44,480 right now the only thing we are headed 763 00:28:42,480 --> 00:28:46,080 for is a collision with andromeda 764 00:28:44,480 --> 00:28:48,399 and anything else which remains in the 765 00:28:46,080 --> 00:28:50,880 local group 766 00:28:48,399 --> 00:28:52,240 our only eventual destination is the 767 00:28:50,880 --> 00:28:54,799 void 768 00:28:52,240 --> 00:28:56,240 the great attractor like all galaxy 769 00:28:54,799 --> 00:28:58,559 clusters and groups 770 00:28:56,240 --> 00:28:59,600 will be dispersed into its constituent 771 00:28:58,559 --> 00:29:01,840 galaxies 772 00:28:59,600 --> 00:29:03,840 each being cast into its own section of 773 00:29:01,840 --> 00:29:06,799 space thanks to the force that drives 774 00:29:03,840 --> 00:29:09,200 the universe's inflation 775 00:29:06,799 --> 00:29:11,279 but hey right now the separation of 776 00:29:09,200 --> 00:29:12,960 galaxies hasn't occurred yet 777 00:29:11,279 --> 00:29:14,720 and it's going to be a pretty long time 778 00:29:12,960 --> 00:29:16,960 before it does 779 00:29:14,720 --> 00:29:18,799 and we are fortunate enough to exist at 780 00:29:16,960 --> 00:29:21,279 a time when we can observe brilliant 781 00:29:18,799 --> 00:29:24,840 cosmic structures like leniencia 782 00:29:21,279 --> 00:29:27,360 without them vanishing over the cosmic 783 00:29:24,840 --> 00:29:29,679 horizon there's just something about 784 00:29:27,360 --> 00:29:30,159 galaxies flowing like great lakes across 785 00:29:29,679 --> 00:29:33,200 space 786 00:29:30,159 --> 00:29:35,120 that seems tantalizing and beautiful and 787 00:29:33,200 --> 00:29:37,840 it is remarkable just how far 788 00:29:35,120 --> 00:29:40,000 gravity propagates and though the great 789 00:29:37,840 --> 00:29:42,480 attractor was a gravitational mystery 790 00:29:40,000 --> 00:29:43,200 for many years the biggest unsolved 791 00:29:42,480 --> 00:29:55,840 mystery 792 00:29:43,200 --> 00:29:55,840 is gravity itself 793 00:29:58,980 --> 00:30:07,960 [Music] 794 00:30:12,960 --> 00:30:15,039 you