1 00:00:07,224 --> 00:00:10,053 TYSON: We inhabit a cosmos of undiscovered dimensions 2 00:00:10,227 --> 00:00:13,230 and paradoxical realities. 3 00:00:13,535 --> 00:00:16,799 We live on one level of perception, 4 00:00:23,023 --> 00:00:26,113 but there are others. 5 00:00:36,471 --> 00:00:39,169 Every once in a while, a searcher happens upon 6 00:00:39,343 --> 00:00:41,911 the doorway to one of these other levels. 7 00:00:45,262 --> 00:00:48,439 One of them discovered a paradox about reality that 8 00:00:48,613 --> 00:00:52,400 proved to be so profound, we have yet to understand 9 00:00:52,574 --> 00:00:55,881 how it could be possible. 10 00:01:03,498 --> 00:01:08,329 The universe, or perhaps we should say, 11 00:01:08,677 --> 00:01:12,724 universes have never been the same. 12 00:01:28,000 --> 00:01:32,483 ♪ ♪ 13 00:01:37,184 --> 00:01:40,187 [theme music plays] 14 00:01:59,554 --> 00:02:04,385 ♪ ♪ 15 00:02:25,319 --> 00:02:30,541 ♪ ♪ 16 00:02:41,639 --> 00:02:44,860 Nature writes her most intimate secrets in light. 17 00:02:46,209 --> 00:02:49,038 The light from our star that powers all life on this world. 18 00:02:50,735 --> 00:02:53,477 The light that plants eat to make sugar. 19 00:02:53,999 --> 00:02:56,088 The light that is the yardstick of the universe, 20 00:02:57,089 --> 00:03:00,136 stitching diamonds into the fabric of space and time. 21 00:03:00,963 --> 00:03:04,227 The imprisoned light that defines black holes. 22 00:03:04,401 --> 00:03:06,577 The absence of light that prevents us from knowing 23 00:03:06,751 --> 00:03:10,451 what dark matter and dark energy are. 24 00:03:10,625 --> 00:03:14,629 "Seeing the light" usually refers to a religious epiphany, 25 00:03:14,803 --> 00:03:17,153 but no one is more light-obsessed than astronomers. 26 00:03:18,154 --> 00:03:20,330 And as soon as they began studying light, 27 00:03:20,504 --> 00:03:23,115 it challenged even the very best of them. 28 00:03:42,004 --> 00:03:43,614 Take Isaac Newton, for example. 29 00:03:51,883 --> 00:03:55,191 He was so desperate to understand the nature of light and colors, 30 00:03:56,105 --> 00:03:58,238 he was willing to stick needles in his eyes. 31 00:03:59,587 --> 00:04:01,589 No, I mean literally. 32 00:04:04,461 --> 00:04:07,029 Newton was only in his mid-20s, 33 00:04:07,203 --> 00:04:11,860 but he had already laid the foundations of a new branch of mathematics called "calculus," 34 00:04:12,600 --> 00:04:14,863 and he was conducting a series 35 00:04:15,037 --> 00:04:18,997 of experiments that led him to conclude that color was an aspect of light. 36 00:04:20,303 --> 00:04:23,088 Newton wanted to find out which of the things we see 37 00:04:23,263 --> 00:04:25,917 are properties of light and which are caused by our nerves. 38 00:04:27,179 --> 00:04:30,270 Was color hiding inside the light? 39 00:04:30,444 --> 00:04:33,142 Or was it in our eyes? 40 00:04:33,490 --> 00:04:35,362 With a burning desire to know, 41 00:04:35,536 --> 00:04:38,365 he took a needle called a bodkin and 42 00:04:55,033 --> 00:04:57,340 Newton carefully noted that if he conducted 43 00:04:57,514 --> 00:05:00,604 the experiment in a room filled with light, 44 00:05:00,778 --> 00:05:03,738 even with his eyes shut, some light would pass through 45 00:05:03,912 --> 00:05:07,481 his eyelids and he would see a great, broad blue-ish circle. 46 00:05:09,309 --> 00:05:12,007 It may not sound like much of a result considering the pain, 47 00:05:12,181 --> 00:05:14,488 but it was with simple homemade experiments such 48 00:05:14,662 --> 00:05:18,361 as this one that Isaac Newton became the first person to explain rainbows, 49 00:05:19,536 --> 00:05:21,364 and how white light hides a whole 50 00:05:21,538 --> 00:05:24,193 palette of colors inside itself. 51 00:05:25,629 --> 00:05:27,675 Most people thought of the events Newton studied as 52 00:05:27,849 --> 00:05:31,026 being just the way things were. 53 00:05:31,418 --> 00:05:32,767 The way an apple falls. 54 00:05:32,941 --> 00:05:36,118 The way a ray of light shines through a window. 55 00:05:36,510 --> 00:05:38,773 Newton's greatness stemmed from his questioning of the 56 00:05:38,947 --> 00:05:41,079 "why" and "how" of ordinary things. 57 00:05:44,431 --> 00:05:47,477 Newton asked, what was light made of? 58 00:05:47,651 --> 00:05:50,524 If you could break light apart into its tiniest components, 59 00:05:50,698 --> 00:05:52,395 what would you see? 60 00:05:52,569 --> 00:05:55,703 Newton noticed that light moved in straight lines. 61 00:05:55,877 --> 00:05:58,793 How else to explain the edges of shadows? 62 00:06:00,142 --> 00:06:02,971 Or the straightness of the inspiring rays of sunlight 63 00:06:03,145 --> 00:06:05,234 that poke through a cloud? 64 00:06:05,408 --> 00:06:09,064 Or the darkness that resulted from a total solar eclipse? 65 00:06:16,158 --> 00:06:19,335 From these observations, Newton reasoned that light 66 00:06:19,509 --> 00:06:22,730 must consist of a stream of particles, 67 00:06:22,904 --> 00:06:25,210 or corpuscles as he called them, 68 00:06:25,385 --> 00:06:27,909 that a ray of light was like a stream of bullets striking 69 00:06:28,083 --> 00:06:30,825 the retina of the eye. 70 00:06:36,134 --> 00:06:39,399 But there was one man over in Holland, 71 00:06:39,964 --> 00:06:43,359 who vigorously disagreed with Newton's particle theory of light. 72 00:06:43,533 --> 00:06:48,016 Christiaan Huygens shared Isaac Newton's insatiable curiosity, 73 00:06:48,190 --> 00:06:50,453 and when it came to changing the world, 74 00:06:50,627 --> 00:06:53,195 he was no slouch himself. 75 00:06:53,369 --> 00:06:56,154 Despite a lifelong struggle with depression, 76 00:06:56,328 --> 00:06:58,592 he managed to get a lot done. 77 00:07:01,551 --> 00:07:04,989 While looking through a telescope that he designed and built himself, 78 00:07:05,163 --> 00:07:08,079 he discovered Saturn's moon, Titan. 79 00:07:25,880 --> 00:07:28,752 Huygens invented the pendulum clock. 80 00:07:28,926 --> 00:07:31,581 He worked out the mathematical formulas necessary to create 81 00:07:31,755 --> 00:07:34,976 a pendulum with an arc that would accurately and 82 00:07:35,150 --> 00:07:38,849 consistently measure out uniform increments of time. 83 00:07:40,590 --> 00:07:43,375 Huygens sketched a prototype for a new machine 84 00:07:43,550 --> 00:07:45,900 that he thought might have some promise. 85 00:07:46,074 --> 00:07:49,251 It was what he called a "magic lantern." 86 00:07:49,686 --> 00:07:51,775 A few hundred years would pass before it evolved into 87 00:07:51,949 --> 00:07:54,125 a working motion picture projector. 88 00:07:54,561 --> 00:07:56,258 But back in the 17th century, 89 00:07:56,432 --> 00:07:59,435 Christiaan Huygens already had an idea for a movie, 90 00:07:59,609 --> 00:08:03,091 possibly influenced by his gloomy disposition. 91 00:08:25,417 --> 00:08:27,115 Huygens, like Newton, 92 00:08:27,289 --> 00:08:30,466 also invented his own new branch of mathematics, 93 00:08:30,640 --> 00:08:34,122 a predictive theory of the outcomes of games of chance, 94 00:08:34,905 --> 00:08:36,690 probability theory. 95 00:08:36,864 --> 00:08:40,520 A way to call heads or tails. 96 00:08:47,352 --> 00:08:51,182 And like Newton, Christiaan Huygens had his own theory of light, 97 00:08:51,618 --> 00:08:53,315 but it was very different. 98 00:08:53,489 --> 00:08:55,447 He didn't think light consisted of particles like 99 00:08:55,622 --> 00:08:58,712 bullets firing along a single path. 100 00:08:58,886 --> 00:09:00,801 Huygens saw light as a wave, 101 00:09:00,975 --> 00:09:03,804 spreading out in all directions. 102 00:09:04,631 --> 00:09:06,894 [speaking in native language]. 103 00:09:07,068 --> 00:09:10,637 TYSON: It was already known in that time that sound must travel as a wave. 104 00:09:10,811 --> 00:09:12,987 How? 105 00:09:13,161 --> 00:09:15,729 Because a voice could be heard around a door when it was slightly ajar, 106 00:09:15,903 --> 00:09:19,471 so sound must travel around the door as water would, 107 00:09:19,646 --> 00:09:21,778 like a wave. 108 00:09:23,084 --> 00:09:27,436 [speaking in native language]. 109 00:09:33,050 --> 00:09:36,140 TYSON: Huygens thought that light moved the same way sound did, 110 00:09:36,314 --> 00:09:38,490 spreading out as waves. 111 00:09:58,598 --> 00:10:01,513 ♪ ♪ 112 00:10:05,779 --> 00:10:09,086 So, which genius was right? 113 00:10:09,260 --> 00:10:11,698 The answer to that question of whether light was a particle 114 00:10:11,872 --> 00:10:15,745 or a wave would prove to be complicated. 115 00:10:16,006 --> 00:10:18,661 Now enter Thomas Young. 116 00:10:20,837 --> 00:10:24,101 The man who exposed the enigma at the heart of light 117 00:10:24,275 --> 00:10:28,758 and unraveled the fabric of the cosmos that we thought we knew. 118 00:10:31,674 --> 00:10:35,678 Come with me to one of the greatest mysteries in the history of science. 119 00:10:38,028 --> 00:10:41,336 It's a story about a man who could do just about anything, 120 00:10:41,510 --> 00:10:44,992 and Thomas Young did. 121 00:10:45,166 --> 00:10:49,431 For 1500 years, no one had been able to decipher Egyptian hieroglyphics. 122 00:10:51,955 --> 00:10:55,089 By identifying six major sounds that the hieroglyphics represented, 123 00:10:56,220 --> 00:10:59,833 he was able to decrypt six of the symbols, 124 00:11:00,747 --> 00:11:02,705 which led to the complete translation of the ancient 125 00:11:02,879 --> 00:11:06,143 Egyptian language by others. 126 00:11:07,318 --> 00:11:10,365 He was the first to chart the family tree of the Indo-European languages. 127 00:11:13,411 --> 00:11:16,545 As a physician, he identified a deformity in the shape of the eye, 128 00:11:17,633 --> 00:11:20,462 the defective vision he named astigmatism. 129 00:11:27,338 --> 00:11:29,950 But it was Young's design of an experiment that sent 130 00:11:30,124 --> 00:11:33,867 physics down the rabbit hole we still live in. 131 00:11:34,041 --> 00:11:36,739 It looks simple, right? 132 00:11:36,913 --> 00:11:41,439 How could three sheets of cardboard set such a catastrophe in motion? 133 00:11:42,266 --> 00:11:46,793 A green glass shade like this one will only allow the green light through, 134 00:11:46,967 --> 00:11:48,708 so that only a single color, 135 00:11:48,882 --> 00:11:51,623 or frequency of light will pass through the slits. 136 00:11:51,798 --> 00:11:53,538 Why was that important? 137 00:11:53,713 --> 00:11:56,411 Because he assumed that the many overlapping colors would 138 00:11:56,585 --> 00:11:59,893 result in the same light wave that Huygens imagined, 139 00:12:00,067 --> 00:12:03,113 called an interference pattern. 140 00:12:03,635 --> 00:12:06,203 He forced that single color of light to travel through 141 00:12:06,377 --> 00:12:09,293 two separate slits to see what kind of pattern the light 142 00:12:09,467 --> 00:12:12,688 would make on that last piece of cardboard. 143 00:12:13,471 --> 00:12:16,344 If light was a particle, you'd expect to see two distinct 144 00:12:16,518 --> 00:12:18,738 clumps of light on the opposite wall, 145 00:12:18,912 --> 00:12:21,131 where the individual particles of light ended up 146 00:12:21,305 --> 00:12:24,134 after they passed through the slits. 147 00:12:24,308 --> 00:12:26,963 But that's not what happened. 148 00:12:30,880 --> 00:12:35,232 Instead, a completely unexpected pattern. 149 00:12:36,843 --> 00:12:39,367 The one that two waves would make when they overlapped, 150 00:12:39,671 --> 00:12:42,544 or interfered with each other. 151 00:12:44,459 --> 00:12:47,854 That's why they're called an interference pattern. 152 00:12:48,419 --> 00:12:52,859 Young had demonstrated that light was actually a wave. 153 00:12:54,121 --> 00:12:58,516 That Newton, the greatest genius in the history of science was half wrong. 154 00:12:58,690 --> 00:13:02,694 That light was not a particle as he confidently proclaimed. 155 00:13:07,134 --> 00:13:09,484 There's a reason that arguments from authority 156 00:13:09,658 --> 00:13:11,878 hold little weight in science. 157 00:13:12,052 --> 00:13:15,185 Nature and nature only settles the argument. 158 00:13:15,359 --> 00:13:18,101 And she has so many tricks up her sleeve, 159 00:13:18,275 --> 00:13:21,801 only a fool would ever consider our understanding of nature complete. 160 00:13:23,585 --> 00:13:26,283 Newton had missed something fundamental. 161 00:13:27,632 --> 00:13:32,812 Surprising, but we haven't gotten to the really disturbing part yet. 162 00:13:44,258 --> 00:13:47,957 TYSON: Thomas Young left a time bomb with a long fuse. 163 00:13:48,131 --> 00:13:51,439 One that took 100 years to burn down before it exploded. 164 00:13:53,093 --> 00:13:56,139 It wasn't until the end of the 19th century that science 165 00:13:56,313 --> 00:14:00,535 developed the necessary tools to find an opening to a hidden universe, 166 00:14:01,449 --> 00:14:04,321 a realm of deeper mystery. 167 00:14:04,887 --> 00:14:08,282 You can hear the discoverer's astonishment in his own account. 168 00:14:09,674 --> 00:14:11,372 THOMSON: Could anything, at first sight, 169 00:14:11,546 --> 00:14:18,205 seem more impractical than a body which is so small that 170 00:14:18,379 --> 00:14:23,427 its mass is an insignificant fraction of the mass of an atom of hydrogen? 171 00:14:25,081 --> 00:14:29,390 Which itself is so small that 172 00:14:29,564 --> 00:14:34,003 the crowd of these atoms equal 173 00:14:34,177 --> 00:14:39,574 in number to the population of the whole world would be too small 174 00:14:40,662 --> 00:14:44,927 to have been detected by any means then known to science. 175 00:14:46,363 --> 00:14:49,236 TYSON: That voice, that particular organization of 176 00:14:49,410 --> 00:14:53,066 sound waves frozen in time nearly 100 years ago, 177 00:14:53,240 --> 00:14:56,199 belongs to J.J. Thomson. 178 00:14:56,373 --> 00:14:59,986 He's remembering his discovery of the electron in his cathode ray experiment. 179 00:15:03,119 --> 00:15:07,036 He had heated up a metal electrode until it spit out an electron. 180 00:15:09,604 --> 00:15:12,389 And another, and another. 181 00:15:16,306 --> 00:15:18,352 For the first time, an elementary particle of 182 00:15:18,526 --> 00:15:21,355 the atom was made visible. 183 00:15:21,529 --> 00:15:24,358 Science was breaking into nature's vault where she had 184 00:15:24,532 --> 00:15:27,230 kept her most closely held secrets, 185 00:15:27,404 --> 00:15:30,233 and that's when things got really crazy. 186 00:15:30,407 --> 00:15:33,236 If even the smallest units of matter, atoms say, 187 00:15:33,410 --> 00:15:36,979 had even smaller components, such as an electron, 188 00:15:37,153 --> 00:15:40,026 then could the same thing be true of light? 189 00:15:40,722 --> 00:15:43,246 Scientists, in their never-ending fascination with light, 190 00:15:43,420 --> 00:15:45,988 set out to devise ways of isolating smaller 191 00:15:46,162 --> 00:15:48,599 and smaller units of it. 192 00:15:48,773 --> 00:15:52,299 It proved to be the passage way through the looking glass. 193 00:15:53,430 --> 00:15:55,911 It was the crossing of a threshold into a wonderland 194 00:15:56,085 --> 00:15:59,393 where the known rules of physics do not apply. 195 00:16:01,047 --> 00:16:04,528 For the first time, they were able to isolate the tiniest unit of light, 196 00:16:05,225 --> 00:16:08,010 a single photon. 197 00:16:11,100 --> 00:16:15,017 And to perform Young's double slit experiment on a whole new level, 198 00:16:15,191 --> 00:16:19,674 tracing its precise path either through the right slit or the left slit. 199 00:16:22,329 --> 00:16:26,507 We'll pull over to the side of the road for the best possible view of which slit, 200 00:16:26,681 --> 00:16:28,248 the right or the left, 201 00:16:28,422 --> 00:16:31,120 the photon passes through to get to the far wall. 202 00:16:32,904 --> 00:16:35,472 Left slit, right slit. 203 00:16:35,646 --> 00:16:36,256 Another right slit. 204 00:16:36,430 --> 00:16:37,605 Left slit. 205 00:16:37,779 --> 00:16:38,910 If we watched them all day long, 206 00:16:39,085 --> 00:16:40,434 the pattern would be random. 207 00:16:40,608 --> 00:16:43,089 About half would go through either slit. 208 00:16:48,833 --> 00:16:51,097 Wait a second. 209 00:16:51,271 --> 00:16:53,273 Where are the waves? 210 00:16:53,447 --> 00:16:56,667 Where is Young's interference pattern? 211 00:16:59,061 --> 00:17:02,325 This is where the weird begins. 212 00:17:02,499 --> 00:17:05,241 I cannot explain to you what you're about to see. 213 00:17:05,415 --> 00:17:09,202 That's because no one on earth understands it yet. 214 00:17:09,724 --> 00:17:11,595 If you can't live with that, 215 00:17:11,769 --> 00:17:15,251 then you're not gonna be happy with what lies up ahead. 216 00:17:15,425 --> 00:17:18,515 On the smallest possible scale that we've ever discovered, 217 00:17:18,689 --> 00:17:23,607 the quantum universe, the mere act of observation changes reality. 218 00:17:25,957 --> 00:17:30,962 Okay, photons, keep on coming, and this time we promise not to look. 219 00:17:33,139 --> 00:17:36,011 You're not gonna believe this, but we can change the pattern 220 00:17:36,185 --> 00:17:39,406 on the far wall simply by not watching which slit the 221 00:17:39,580 --> 00:17:41,930 photons pass through. 222 00:17:42,104 --> 00:17:45,716 I know it sounds crazy, but in every trial ever conducted, 223 00:17:45,890 --> 00:17:49,677 the outcome depends on whether or not the experiment was observed. 224 00:18:08,739 --> 00:18:11,002 So, the reason we didn't get the interference pattern 225 00:18:11,177 --> 00:18:15,572 earlier wasn't because we chopped up the light into single photons, 226 00:18:15,746 --> 00:18:18,053 it was because we were observing which slit 227 00:18:18,227 --> 00:18:21,230 the photons passed through, 228 00:18:21,404 --> 00:18:25,669 but how can a photon know if someone is watching? 229 00:18:25,843 --> 00:18:27,628 A photon doesn't have eyes. 230 00:18:27,802 --> 00:18:30,109 A photon doesn't have a brain. 231 00:18:30,283 --> 00:18:33,677 How could it know it was being watched? 232 00:18:33,851 --> 00:18:36,593 You might reasonably conclude that a single photon is such 233 00:18:36,767 --> 00:18:40,771 a tiny thing that it's very hard to see without using complex technology. 234 00:18:42,425 --> 00:18:45,298 This machinery does violence to the delicate photon. 235 00:18:46,864 --> 00:18:50,041 It changes it, but that doesn't explain why photons 236 00:18:50,216 --> 00:18:53,306 behave like particles when we're watching but waves when we're not. 237 00:18:54,872 --> 00:18:56,874 If light is fundamentally a particle, 238 00:18:57,048 --> 00:18:59,268 then it should never create a wave pattern, 239 00:18:59,442 --> 00:19:02,228 whether we're observing it or not. 240 00:19:02,402 --> 00:19:06,101 And how can individual photons know where to take their places, 241 00:19:06,275 --> 00:19:09,496 so that as a group they create the interference patterns of waves? 242 00:19:11,411 --> 00:19:16,067 This is a maddening conundrum at the heart of quantum physics. 243 00:19:17,765 --> 00:19:20,289 Isaac Newton and Christiaan Huygens were both 244 00:19:20,463 --> 00:19:24,685 equally right and equally wrong. 245 00:19:25,947 --> 00:19:29,516 Light is both a wave and a particle, and neither. 246 00:19:31,257 --> 00:19:33,084 Until we make an observation, 247 00:19:33,259 --> 00:19:36,958 the photon exists in a state of uncertainty, 248 00:19:37,132 --> 00:19:39,569 governed by laws of probability. 249 00:19:39,743 --> 00:19:41,397 And when we do observe it, 250 00:19:41,571 --> 00:19:44,835 it becomes something completely different. 251 00:19:46,837 --> 00:19:50,841 We would be lost in the quantum universe without Christiaan Huygens. 252 00:19:51,015 --> 00:19:53,931 His probability theory provides, even now, 253 00:19:54,105 --> 00:19:58,936 the only key we have to grasping the laws of quantum reality. 254 00:19:59,372 --> 00:20:01,765 Every particle is at the mercy of random chance 255 00:20:01,939 --> 00:20:04,464 and shifting probabilities. 256 00:20:04,638 --> 00:20:08,294 Thinking about it is like looking at an optical illusion, 257 00:20:08,468 --> 00:20:10,209 you can only grab hold of it for moments at 258 00:20:10,383 --> 00:20:13,821 a time before it pops back into something else. 259 00:20:19,566 --> 00:20:21,611 In the quantum universe, there's an undiscovered 260 00:20:21,785 --> 00:20:25,398 frontier where the laws of our world give way to the ones 261 00:20:25,572 --> 00:20:28,270 that apply on the tiniest scale we know. 262 00:20:29,532 --> 00:20:32,492 They're divorced from our everyday experience. 263 00:20:33,406 --> 00:20:37,236 How can you think about a world that has different rules than ours? 264 00:20:37,410 --> 00:20:39,455 It's not easy. 265 00:20:39,629 --> 00:20:42,110 That's why I want to take you to this place where it's not 266 00:20:42,284 --> 00:20:46,157 only possible to make such a leap, it's mandatory. 267 00:20:47,115 --> 00:20:50,074 It's a world very much like our own, 268 00:20:50,249 --> 00:20:52,686 except in one respect. 269 00:21:02,957 --> 00:21:07,266 It just happens to be missing a spatial dimension, 270 00:21:07,440 --> 00:21:08,963 the third one. 271 00:21:13,359 --> 00:21:15,970 TYSON: In order to venture into the quantum cosmos, 272 00:21:16,144 --> 00:21:18,451 we have to be able to imagine another dimension. 273 00:21:19,234 --> 00:21:21,584 That's very hard to do. 274 00:21:21,758 --> 00:21:24,326 It's much easier to wrap your mind around a world that's 275 00:21:24,500 --> 00:21:28,069 missing one of the three dimensions that we take for granted. 276 00:21:28,243 --> 00:21:32,291 The beings of the world we're about to enter have only two. 277 00:21:32,465 --> 00:21:36,904 This world was first imagined by a man named Edwin Abbott. 278 00:21:37,078 --> 00:21:40,168 Everyone and everything here and everyone they know 279 00:21:40,342 --> 00:21:43,040 and love is flat. 280 00:21:43,214 --> 00:21:45,347 Their houses are flat. 281 00:21:45,521 --> 00:21:49,220 Some are squares, others are triangles. 282 00:21:49,395 --> 00:21:53,181 Some have more complex shapes, say octagons. 283 00:21:53,355 --> 00:21:56,576 But all are completely flat. 284 00:21:56,750 --> 00:21:59,883 They scurry about on foot or in little vehicles, 285 00:22:00,057 --> 00:22:02,103 in and out of their flat buildings, 286 00:22:02,277 --> 00:22:04,410 busy with their flat lives. 287 00:22:04,584 --> 00:22:08,196 Everyone on this world has width and length, 288 00:22:08,370 --> 00:22:11,460 but no height whatsoever. 289 00:22:11,634 --> 00:22:14,811 These Flatworlders know about left-right and forward-back, 290 00:22:16,073 --> 00:22:19,860 but have no hint, not an inkling, about up-down, 291 00:22:20,034 --> 00:22:22,645 except for one tiny group, 292 00:22:22,819 --> 00:22:26,345 the mathematicians, who imagine something more. 293 00:22:28,695 --> 00:22:32,786 The mathematicians dream of a world in three dimensions, 294 00:22:32,960 --> 00:22:36,746 but it's too hard for most of the Flatworlders to think about. 295 00:22:36,920 --> 00:22:38,792 The mathematician says, 296 00:22:38,966 --> 00:22:41,403 "Listen, it's really very easy. 297 00:22:41,577 --> 00:22:43,013 We all know left-right. 298 00:22:43,187 --> 00:22:45,451 We all know forward-back. 299 00:22:45,625 --> 00:22:49,237 So let's just imagine another dimension at right-angles to the other two." 300 00:22:50,151 --> 00:22:51,805 But the Flatworlders say, 301 00:22:51,979 --> 00:22:53,415 "What are you talking about? 302 00:22:53,589 --> 00:22:55,591 At right angles to the other two? 303 00:22:55,765 --> 00:22:59,073 Everybody knows that there can only be two dimensions. 304 00:22:59,247 --> 00:23:02,555 Go ahead, wise guy, show us that third dimension. 305 00:23:02,729 --> 00:23:05,035 Where is it?" 306 00:23:05,471 --> 00:23:07,777 So the mathematician draws a picture. 307 00:23:15,132 --> 00:23:16,482 Poor teacher. 308 00:23:16,656 --> 00:23:19,920 Nobody listens to mathematicians. 309 00:23:24,272 --> 00:23:28,668 Every creature on flatworld sees its fellows as merely short lines, 310 00:23:29,843 --> 00:23:33,368 which are the nearest sides of their oblong bodies. 311 00:23:33,890 --> 00:23:37,459 But the insides of a Flatworlder are forever mysterious, 312 00:23:37,633 --> 00:23:41,420 unless exposed by some terrible accident or autopsy. 313 00:23:43,073 --> 00:23:46,120 And then one day, we came along. 314 00:23:50,211 --> 00:23:54,302 Hello? How are you? 315 00:23:55,085 --> 00:23:58,785 Hi, I'm a visitor from the third dimension. 316 00:23:59,176 --> 00:24:03,180 Hello? I feel sorry for the little guy. 317 00:24:03,354 --> 00:24:07,315 To him, it appears that my greeting is emanating from his own flat body, 318 00:24:08,621 --> 00:24:11,232 an alien voice from within. 319 00:24:11,406 --> 00:24:13,277 That's because nothing can come from above. 320 00:24:13,452 --> 00:24:16,019 There is no above in this world. 321 00:24:16,193 --> 00:24:19,196 A three-dimensional creature like me can only exist 322 00:24:19,370 --> 00:24:23,679 on Flatworld where my feet touch the surface of the plane. 323 00:24:27,727 --> 00:24:29,598 Sorry, little guy. 324 00:24:29,772 --> 00:24:32,514 I know how weird this must be for you. 325 00:24:32,688 --> 00:24:34,385 Don't worry. 326 00:24:34,560 --> 00:24:38,215 You'll have a perfectly safe trip to the third dimension. 327 00:24:38,738 --> 00:24:40,696 Nothing's gonna harm you. 328 00:24:40,870 --> 00:24:43,743 But this is your chance to see a whole new perspective 329 00:24:43,917 --> 00:24:46,876 on where you live. 330 00:24:47,050 --> 00:24:50,358 At first, our Flatworlder can make no sense of what is happening. 331 00:24:50,532 --> 00:24:53,753 It's utterly outside the realm of Flatworld experience. 332 00:24:54,623 --> 00:24:57,191 But eventually he realizes that he's viewing Flatworld 333 00:24:57,365 --> 00:25:00,977 from a totally new vantage point above. 334 00:25:01,282 --> 00:25:03,937 Now, he can see into closed rooms. 335 00:25:04,111 --> 00:25:06,592 He can see into his flat fellows. 336 00:25:06,766 --> 00:25:09,159 This unprecedented three-dimensional view of 337 00:25:09,333 --> 00:25:13,033 his two-dimensional universe is devastating. 338 00:25:13,773 --> 00:25:16,471 Traveling to another dimension provides as an incidental benefit, 339 00:25:16,645 --> 00:25:18,952 a kind of X-ray vision. 340 00:25:19,126 --> 00:25:21,998 Just as the Flatworld houses can have no roofs, 341 00:25:22,172 --> 00:25:24,523 their inhabitants can have no sky, 342 00:25:24,697 --> 00:25:28,309 because that sky could only exist in a third-dimension. 343 00:25:29,310 --> 00:25:31,442 Little guy's suffered enough. 344 00:25:31,617 --> 00:25:35,534 Better put him down. 345 00:25:35,838 --> 00:25:37,579 From the point of view of its spouse, 346 00:25:37,753 --> 00:25:40,321 this Flatworlder has distressingly disappeared, 347 00:25:40,495 --> 00:25:44,064 then unaccountably materialized from out of nowhere. 348 00:26:09,306 --> 00:26:11,831 It's easier to imagine the universe in fewer dimensions 349 00:26:12,005 --> 00:26:14,007 than our comfort zone of three. 350 00:26:14,181 --> 00:26:17,706 A zero-dimensional universe is just a point. 351 00:26:17,880 --> 00:26:20,840 A dot with no dimension at all. 352 00:26:22,668 --> 00:26:26,628 Or a one-dimensional universe where everyone is a line segment. 353 00:26:27,586 --> 00:26:32,416 Or the two-dimensional Flatworld. 354 00:26:33,809 --> 00:26:36,595 Or 3D, where we all live. 355 00:26:40,860 --> 00:26:42,209 We can laugh at the cluelessness of 356 00:26:42,383 --> 00:26:44,080 two-dimensional creatures. 357 00:26:44,777 --> 00:26:47,127 Unable to imagine a three-dimensional world. 358 00:26:47,301 --> 00:26:51,479 But, when it comes to quantum reality, that inability, 359 00:26:51,653 --> 00:26:55,004 resembles the problems we have. 360 00:26:55,178 --> 00:26:57,746 The best we can do for now is to imagine this 361 00:26:57,920 --> 00:27:01,750 three-dimensional cube as a four-dimensional hypercube. 362 00:27:04,318 --> 00:27:06,842 We're living in our own Flatworld, 363 00:27:07,016 --> 00:27:09,323 just like the 19th Century writer, Edwin Abbott, 364 00:27:09,497 --> 00:27:11,760 in his book Flatland, was trying. 365 00:27:20,769 --> 00:27:22,858 TYSON: It's the rarest of events, 366 00:27:23,032 --> 00:27:25,731 when a searcher happens on a hole in the curtain 367 00:27:25,905 --> 00:27:29,082 that hides the matrix. 368 00:27:30,953 --> 00:27:34,000 It was not until Isaac Newton that we began to understand 369 00:27:34,174 --> 00:27:37,133 the motions of the worlds. 370 00:27:37,307 --> 00:27:40,441 The variety of living things always astonished us, 371 00:27:42,312 --> 00:27:45,620 but Charles Darwin discovered how time and the environment 372 00:27:45,794 --> 00:27:48,667 sculpted these forms, including us, 373 00:27:48,928 --> 00:27:53,280 from life's first living cell. 374 00:27:53,454 --> 00:27:56,239 We had no idea that the quantum universe even existed 375 00:27:56,413 --> 00:27:59,460 until Albert Einstein revealed it. 376 00:27:59,982 --> 00:28:04,900 The mysterious laws of this paradoxical cosmos deeply disturbed him. 377 00:28:05,074 --> 00:28:08,774 And we have yet to understand them ourselves. 378 00:28:10,079 --> 00:28:12,125 At its heart, was a relationship that seemed 379 00:28:12,299 --> 00:28:15,432 to violate the speed of light. 380 00:28:15,606 --> 00:28:19,219 The backbone of modern physics and reality itself. 381 00:28:22,788 --> 00:28:25,616 That blue photon, a quantum packet of light, 382 00:28:25,791 --> 00:28:28,707 will divide into two. 383 00:28:28,881 --> 00:28:32,754 Splitting its energy and emerging as a pair of red photons. 384 00:28:34,713 --> 00:28:38,673 These new red photons are married in the most profound physical sense or, 385 00:28:39,674 --> 00:28:42,982 as quantum physicists say, entangled. 386 00:28:44,679 --> 00:28:47,029 And no matter how far they wander from each other, 387 00:28:47,203 --> 00:28:50,946 in space and in time, the bond between them will endure. 388 00:28:53,427 --> 00:28:56,735 It's a little like Plato's Ancient Greek explanation of love. 389 00:28:57,300 --> 00:29:00,739 A single being splits into two and separates. 390 00:29:02,044 --> 00:29:03,698 For the rest of their existence, 391 00:29:03,872 --> 00:29:07,049 each remains the one and only soul mate of the other. 392 00:29:07,484 --> 00:29:10,531 Exquisitely attuned to the inner life of its partner. 393 00:29:11,314 --> 00:29:15,144 Even if they are separated from each other by a whole universe. 394 00:29:16,580 --> 00:29:19,627 Observe the spin of one photon and you will instantly know 395 00:29:19,801 --> 00:29:22,282 the spin of its entangled partner. 396 00:29:22,456 --> 00:29:25,589 It's not something special about these particular photons. 397 00:29:25,764 --> 00:29:28,767 As far as we know, it's the rule. 398 00:29:30,072 --> 00:29:32,248 This kind of long distance relationship has been going 399 00:29:32,422 --> 00:29:35,556 on for the whole history of the universe. 400 00:29:40,082 --> 00:29:44,086 Two photons born in the early universe nearly 14 billion years ago, 401 00:29:45,435 --> 00:29:48,221 separate and head in opposite directions. 402 00:29:49,962 --> 00:29:53,095 They could end up tens of billions of light-years apart and yet, 403 00:29:53,269 --> 00:29:57,099 over all that time and across all that space, 404 00:29:57,273 --> 00:30:00,407 the bond between them endures. 405 00:30:01,364 --> 00:30:03,758 What is it about a photon or an electron or any other 406 00:30:03,932 --> 00:30:06,543 elementary particle, once entangled, 407 00:30:06,717 --> 00:30:09,851 that makes them capable of such lasting fidelity? 408 00:30:10,547 --> 00:30:12,593 And to me, an even stranger fact, 409 00:30:12,767 --> 00:30:15,857 is that all it takes to sever that awesome commitment, 410 00:30:16,031 --> 00:30:18,468 is the simple act of measurement. 411 00:30:18,642 --> 00:30:22,124 All I have to do is measure the spin of one of them. 412 00:30:23,691 --> 00:30:27,129 How can it be that only one seemingly innocuous act 413 00:30:27,303 --> 00:30:31,786 by a third party can forever sever such a deep and enduring bond? 414 00:30:42,579 --> 00:30:43,667 There she is. 415 00:30:43,842 --> 00:30:46,235 Half of our cosmic couple. 416 00:30:46,757 --> 00:30:49,325 Somewhere, at this very moment, 417 00:30:49,499 --> 00:30:52,154 many billions of light-years away from us, 418 00:30:52,328 --> 00:30:55,854 her soul mate is suddenly feeling something different. 419 00:30:56,637 --> 00:30:58,900 The thrill is gone. 420 00:30:59,379 --> 00:31:02,164 The bond has been broken. 421 00:31:02,730 --> 00:31:05,472 They are no long entangled with each other. 422 00:31:07,169 --> 00:31:10,738 Our simple act of observing one of them has ruined 423 00:31:10,912 --> 00:31:14,394 a marriage that has lasted since the beginning of time. 424 00:31:15,482 --> 00:31:17,397 But, how could that be? 425 00:31:17,571 --> 00:31:20,313 And that's not the only crazy thing about this. 426 00:31:20,487 --> 00:31:24,186 How could one photon, a cosmos away from its partner, 427 00:31:24,360 --> 00:31:28,016 send a break-up message across the universe and have 428 00:31:28,190 --> 00:31:31,672 the other photon receive it instantaneously? 429 00:31:32,586 --> 00:31:35,284 Faster than the speed of light could possibly carry 430 00:31:35,458 --> 00:31:38,244 such a message between them. 431 00:31:42,683 --> 00:31:47,079 These are two of the greatest unanswered questions in science. 432 00:31:47,253 --> 00:31:50,386 So, don't worry if they bother you. 433 00:31:50,560 --> 00:31:54,086 These questions haunted a mind as great as Einstein's for the rest of his life. 434 00:31:56,697 --> 00:32:00,570 There's nothing more intriguing to a scientist than a paradox. 435 00:32:01,267 --> 00:32:03,617 If light, the fastest thing there can be, 436 00:32:03,791 --> 00:32:06,881 has a cosmic speed limit, then it would be impossible 437 00:32:07,055 --> 00:32:11,712 for one photon to communicate with another instantly across such vastness. 438 00:32:13,366 --> 00:32:16,847 Einstein found it almost unbearable to live in this kind of universe. 439 00:32:17,413 --> 00:32:20,808 Where what he called, "spooky" action at a distance was possible. 440 00:32:32,211 --> 00:32:35,127 Remember those particles in the double slit experiment? 441 00:32:35,301 --> 00:32:38,173 Taking either the left or the right slit? 442 00:32:38,347 --> 00:32:42,221 Those choices amounted to nothing more than random chance, 443 00:32:42,395 --> 00:32:45,920 but even random chance must follow certain rules. 444 00:32:46,094 --> 00:32:48,836 That's the basis for Huygens's probability theory and 445 00:32:49,010 --> 00:32:52,622 for calculating the odds in flipping a coin or throwing dice. 446 00:32:54,276 --> 00:32:56,583 When Einstein applied probability theory to the 447 00:32:56,757 --> 00:33:00,456 problem of entangled protons, he was deeply disturbed. 448 00:33:01,631 --> 00:33:05,287 If these photons could brazenly violate the speed of light, 449 00:33:05,461 --> 00:33:08,464 then the universe and all of creation was nothing 450 00:33:08,638 --> 00:33:12,425 more than a casino where the laws of nature can be broken. 451 00:33:14,035 --> 00:33:17,082 Einstein dealt with his discomfort by clinging to the 452 00:33:17,256 --> 00:33:20,999 idea that the dice was somehow loaded in a way we didn't yet understand. 453 00:33:22,870 --> 00:33:25,612 We had passed this way before. 454 00:33:25,786 --> 00:33:30,095 More than 100,000 years ago, our ancestors domesticated fire. 455 00:33:31,705 --> 00:33:33,620 They didn't know what fire was, 456 00:33:33,794 --> 00:33:37,406 but they used it anyway to build a civilization. 457 00:33:37,580 --> 00:33:40,670 And so it was with quantum physics. 458 00:33:40,844 --> 00:33:43,325 We didn't need to understand it to exploit its countless 459 00:33:43,499 --> 00:33:46,676 practical applications, scientific and technological. 460 00:33:48,417 --> 00:33:52,552 Much as our ancestors used fire without understanding how it worked, 461 00:33:52,726 --> 00:33:55,294 we lived with this mystery for decades. 462 00:33:57,209 --> 00:34:00,951 We have entered a territory beyond the reach of classical physics. 463 00:34:01,126 --> 00:34:03,911 Where the elementary particles that make up everything, 464 00:34:04,085 --> 00:34:07,871 including us, respond to events they can't possibly know about. 465 00:34:10,309 --> 00:34:13,747 In the outlaw casino of the quantum universe, 466 00:34:13,921 --> 00:34:17,533 there is no objective reality. 467 00:34:21,624 --> 00:34:24,627 And that's where we're headed next. 468 00:34:32,983 --> 00:34:35,769 TYSON: We are made of atoms. 469 00:34:35,943 --> 00:34:39,425 The bizarre quantum universe is inside us, 470 00:34:39,599 --> 00:34:42,080 tugged on by undiscovered moons. 471 00:34:42,254 --> 00:34:46,084 Performing its impossible magic on every level of life and experience. 472 00:34:47,955 --> 00:34:50,044 What is this? 473 00:34:50,218 --> 00:34:53,700 A smattering of stars or something else? 474 00:34:54,004 --> 00:34:57,573 We are sending an image made of light to your eyes. 475 00:34:57,747 --> 00:35:00,707 It's arriving at your retina at this very moment. 476 00:35:00,881 --> 00:35:03,927 The cells in your retina are changing chemically right 477 00:35:04,102 --> 00:35:07,888 now because we are stimulating some of them with photons. 478 00:35:08,062 --> 00:35:11,935 Your retina stores these changes for a fraction of a second. 479 00:35:12,110 --> 00:35:15,635 Now, it's erasing them in readiness for the next barrage of photons. 480 00:35:17,071 --> 00:35:19,943 Your retina doesn't detect all of them, it can't. 481 00:35:20,944 --> 00:35:24,296 It picks up on only a small percentage of photons that come your way. 482 00:35:25,427 --> 00:35:28,387 It's impossible to predict which particular cell in your 483 00:35:28,561 --> 00:35:31,520 retina will catch a photon. 484 00:35:31,694 --> 00:35:34,262 Even when it comes to something as vital as our vision, 485 00:35:34,436 --> 00:35:38,353 all we have is our probabilities. 486 00:35:40,268 --> 00:35:43,228 Now, we're shooting many more photons at you. 487 00:35:43,402 --> 00:35:45,230 More like, half a million. 488 00:35:45,404 --> 00:35:47,101 What are you looking at? 489 00:35:47,275 --> 00:35:50,365 The surface of some planet orbiting another star? 490 00:35:50,539 --> 00:35:53,890 We need still more of those photons to know for sure. 491 00:35:54,064 --> 00:35:56,632 Say, a couple of million or more. 492 00:35:56,806 --> 00:35:59,722 Only when we send all of those photons your way, 493 00:35:59,896 --> 00:36:01,811 tens of millions of them, 494 00:36:01,985 --> 00:36:05,032 does reality begin to take shape. 495 00:36:05,206 --> 00:36:09,906 Over time, probabilities become likelihoods and eventually, 496 00:36:10,080 --> 00:36:13,736 likelihoods become certainties. 497 00:36:13,910 --> 00:36:17,262 But is there really any such thing as certainty. 498 00:36:17,436 --> 00:36:19,916 If everything, even our own vision, 499 00:36:20,090 --> 00:36:22,310 is governed by probabilities, 500 00:36:22,484 --> 00:36:25,661 can there be any absolute reality? 501 00:36:28,011 --> 00:36:31,406 Is there any hope of rescuing our classical idea 502 00:36:31,580 --> 00:36:35,062 of reality in the quantum universe? 503 00:36:35,845 --> 00:36:37,673 Scientists have come up with one way to preserve our 504 00:36:37,847 --> 00:36:40,459 traditional understanding of cause and effect called 505 00:36:40,633 --> 00:36:43,113 "The Many Worlds Hypothesis." 506 00:36:44,071 --> 00:36:47,422 That's a misnomer because it can't be tested scientifically, 507 00:36:47,596 --> 00:36:49,729 but it goes like this. 508 00:36:49,903 --> 00:36:53,646 Every probability that can happen does happen in 509 00:36:53,820 --> 00:36:58,085 some parallel cosmos that is foreclosed to us. 510 00:36:58,259 --> 00:37:01,001 An infinite number of ever branching realities. 511 00:37:01,175 --> 00:37:05,223 Unfolding at every possible juncture. 512 00:37:05,962 --> 00:37:09,531 Every probability that can happen does happen 513 00:37:09,705 --> 00:37:12,708 in some parallel cosmos... 514 00:37:14,623 --> 00:37:16,408 ♪ MAN: Oh, we need the funk ♪ 515 00:37:16,582 --> 00:37:18,192 ♪ Gotta have that funk ♪ 516 00:37:18,366 --> 00:37:20,499 ♪ Oh, we want the funk ♪♪♪ 517 00:37:20,673 --> 00:37:24,372 TYSON: Or is probability just an illusion itself? 518 00:37:24,546 --> 00:37:27,288 A phantom of our ignorance? 519 00:37:27,462 --> 00:37:30,900 It is, if we live in a universe where every single 520 00:37:31,074 --> 00:37:36,123 event was already foreordained at the beginning of time. 521 00:37:36,297 --> 00:37:39,474 What is called, superdeterminism. 522 00:37:54,881 --> 00:37:57,275 In a superdeterministic universe, 523 00:37:57,449 --> 00:38:01,540 the catastrophic failure of treaties, a sneeze. 524 00:38:01,714 --> 00:38:04,499 The asteroid that wiped out the dinosaurs, 525 00:38:04,673 --> 00:38:08,677 one particular bee pollinating one particular flower. 526 00:38:08,851 --> 00:38:12,855 You listening to me right now, all of these events were set 527 00:38:13,029 --> 00:38:16,903 in lockstep motion at the moment the universe began. 528 00:38:17,251 --> 00:38:21,081 When it was all no larger than a marble. 529 00:38:26,391 --> 00:38:29,437 Superdeterminism has an additional virtue. 530 00:38:29,611 --> 00:38:33,093 It can explain mystery of entanglement. 531 00:38:33,267 --> 00:38:37,750 The ability of entangled particles to communicate across the vastness, 532 00:38:37,924 --> 00:38:41,667 apparently violating the speed limit of light. 533 00:38:41,841 --> 00:38:44,191 In a superdeterministic cosmos, 534 00:38:44,365 --> 00:38:48,108 entangled partners separated by whole galaxies, 535 00:38:48,282 --> 00:38:51,677 don't need to hear from each other to change their spin. 536 00:38:51,851 --> 00:38:56,464 They were always destined to do so at that precise moment. 537 00:38:57,422 --> 00:38:59,511 And so were their partners. 538 00:38:59,685 --> 00:39:01,208 And so was the intruder, 539 00:39:01,382 --> 00:39:04,516 who severed their bond by observing one of them. 540 00:39:09,434 --> 00:39:10,739 Think of it. 541 00:39:10,913 --> 00:39:15,265 All these events and trillions of others, 542 00:39:17,137 --> 00:39:21,881 inscribed in the potential of the first moment of the universe. 543 00:39:22,055 --> 00:39:24,492 Since everything in the universe is made of those 544 00:39:24,666 --> 00:39:27,408 same elementary particles, including us, 545 00:39:27,582 --> 00:39:31,543 we are subject to the same laws as those that rule 546 00:39:31,717 --> 00:39:33,371 the quantum universe. 547 00:39:33,545 --> 00:39:37,984 And so it is, for what will happen next. 548 00:39:38,376 --> 00:39:41,901 And what will happen after that. 549 00:39:47,472 --> 00:39:50,126 The good news is superdeterminism gives us 550 00:39:50,300 --> 00:39:53,129 a solution to the mystery of entanglement, 551 00:39:53,303 --> 00:39:54,653 the bad news is, 552 00:39:54,827 --> 00:39:57,482 it seems to rob us of all agency. 553 00:39:57,656 --> 00:39:59,571 Are we just going through the motions, 554 00:39:59,745 --> 00:40:01,703 acting out a script that was written for us nearly 555 00:40:01,877 --> 00:40:04,140 14 billion years ago? 556 00:40:04,314 --> 00:40:05,838 All the while, 557 00:40:06,012 --> 00:40:08,275 telling ourselves how clever we were in that argument. 558 00:40:08,449 --> 00:40:11,452 How selfish, how brave. 559 00:40:11,974 --> 00:40:14,847 If you could only change that one little thing about yourself. 560 00:40:16,718 --> 00:40:19,721 In a universe devoid of free will, 561 00:40:19,895 --> 00:40:23,421 are we nothing more than deterministic robots? 562 00:40:24,596 --> 00:40:28,948 [church bells ringing] 563 00:40:43,441 --> 00:40:47,575 We have found a way to hitch a ride on the uncertainties. 564 00:40:47,749 --> 00:40:51,884 To forge technologies that would otherwise be unattainable. 565 00:40:52,188 --> 00:40:54,408 We have built a quantum clock. 566 00:40:54,582 --> 00:40:56,671 One that you never have to wind. 567 00:40:56,845 --> 00:41:02,329 It will only lose a single second in the next 15 billion years. 568 00:41:10,555 --> 00:41:14,167 A three-dimensional lattice of laser light keeps isolated 569 00:41:14,341 --> 00:41:16,169 atoms of the element strontium, 570 00:41:16,343 --> 00:41:19,433 suspended in space. 571 00:41:19,868 --> 00:41:22,480 For all we know, we may be near collections 572 00:41:22,654 --> 00:41:26,092 of preprogrammed particles in a deterministic universe. 573 00:41:27,833 --> 00:41:31,706 But I say, let's not live like we are. 574 00:41:31,880 --> 00:41:35,057 Besides, we have no way of knowing if that's true. 575 00:41:36,929 --> 00:41:39,105 And to think that, in some sense, 576 00:41:39,279 --> 00:41:42,238 our freedom to explore the quantum realm begins 577 00:41:42,412 --> 00:41:45,372 with Thomas Young. 578 00:41:46,025 --> 00:41:48,593 Remember, it was Young who also found the key to 579 00:41:48,767 --> 00:41:51,987 decrypting the lost language of the ancient Egyptians. 580 00:41:58,211 --> 00:42:01,823 With quantum encryption, we are creating codes that 581 00:42:01,997 --> 00:42:05,479 vanish the moment someone tries to hack into them. 582 00:42:05,653 --> 00:42:08,961 The key to the code, can be sent via entangled photons. 583 00:42:10,266 --> 00:42:13,226 The observer effect is our insurance policy that no 584 00:42:13,400 --> 00:42:16,446 spy can decipher the message without causing the 585 00:42:16,621 --> 00:42:19,319 entanglement to break apart. 586 00:42:19,754 --> 00:42:22,191 Rendering the message unintelligible. 587 00:42:25,455 --> 00:42:28,154 We still don't know how a photon can be both a particle 588 00:42:28,328 --> 00:42:31,374 and a wave at the same time. 589 00:42:32,288 --> 00:42:34,595 What I love about science, is that it demands of us, 590 00:42:34,769 --> 00:42:37,642 a tolerance for ambiguity. 591 00:42:37,816 --> 00:42:41,733 It requires us to live with humility regarding our ignorance, 592 00:42:41,907 --> 00:42:44,692 withholding judgement until the evidence comes in. 593 00:42:46,259 --> 00:42:49,349 That needn't prevent us from using the little we do know 594 00:42:49,523 --> 00:42:53,135 to search for and decrypt new languages of reality. 595 00:42:57,183 --> 00:43:00,795 In this vast cosmos, we are all Flatworlders. 596 00:43:04,277 --> 00:43:09,369 Science is the struggle to imagine and find above. 597 00:43:52,934 --> 00:43:53,631 Captioned by Cotter Captioning Services.