1 00:00:06,439 --> 00:00:09,976 ♪ ♪ 2 00:00:10,009 --> 00:00:11,677 NARRATOR: We live in a world 3 00:00:11,710 --> 00:00:14,714 where objects have permanence. 4 00:00:14,747 --> 00:00:18,684 And we see cause, then effect. 5 00:00:18,717 --> 00:00:21,754 But a startling phenomenon is revealing 6 00:00:21,787 --> 00:00:23,156 that this is not how the universe works 7 00:00:23,189 --> 00:00:26,959 at the smallest scales of atoms and tiny particles. 8 00:00:26,992 --> 00:00:28,928 ♪ ♪ 9 00:00:28,961 --> 00:00:33,099 Albert Einstein argued it couldn't possibly be real. 10 00:00:33,132 --> 00:00:35,768 DAVID KAISER: Einstein was like a jack-in-the-box; 11 00:00:35,801 --> 00:00:38,304 every day, he'd pop up with a new challenge. 12 00:00:38,337 --> 00:00:41,340 NARRATOR: But after a century of disputes and discoveries... 13 00:00:41,373 --> 00:00:43,509 ANTON ZEILINGER: The experiment is just beautiful. 14 00:00:43,542 --> 00:00:48,448 NARRATOR: ...we're using it to create revolutionary, new technologies. 15 00:00:48,481 --> 00:00:51,217 What we have here is a quantum playground. 16 00:00:51,250 --> 00:00:53,820 JIAN-WEI PAN: We want to push these technologies 17 00:00:53,853 --> 00:00:55,254 as far as possible. 18 00:00:55,287 --> 00:00:58,458 NARRATOR: It's perhaps the strangest concept in physics. 19 00:00:58,491 --> 00:01:01,394 SHOHINI GHOSE: We're left with conclusions that make no sense whatsoever. 20 00:01:01,427 --> 00:01:05,331 NARRATOR: Yet it could be what forms the very fabric of our cosmos. 21 00:01:05,364 --> 00:01:07,800 In the end, we just have this quantum mechanical world. 22 00:01:07,833 --> 00:01:09,102 There is no space anymore. 23 00:01:09,135 --> 00:01:11,537 GHOSE: It's like being in "Alice in Wonderland." 24 00:01:11,570 --> 00:01:13,206 Everything is possible. 25 00:01:13,239 --> 00:01:16,309 NARRATOR: Could it be real? 26 00:01:16,342 --> 00:01:19,645 It's "Einstein's Quantum Riddle," 27 00:01:19,678 --> 00:01:22,482 right now, on "NOVA." 28 00:01:22,515 --> 00:01:27,020 ♪ ♪ 29 00:01:34,693 --> 00:01:38,664 ♪ ♪ 30 00:01:40,598 --> 00:01:44,670 NARRATOR: Is reality an illusion? 31 00:01:44,703 --> 00:01:48,107 Could something here mysteriously affect 32 00:01:48,140 --> 00:01:50,843 something there? 33 00:01:50,876 --> 00:01:53,613 A century of discoveries in physics 34 00:01:53,646 --> 00:01:56,616 reveals a strange, counterintuitive micro-world 35 00:01:56,649 --> 00:01:58,884 of atoms and tiny particles 36 00:01:58,918 --> 00:02:01,621 that challenges our intuitive understanding 37 00:02:01,654 --> 00:02:04,457 of the world we see around us. 38 00:02:05,991 --> 00:02:10,463 It's known as quantum mechanics. 39 00:02:10,496 --> 00:02:12,064 This strange theory has enabled us to develop 40 00:02:12,097 --> 00:02:16,035 the remarkable technologies of our digital age. 41 00:02:16,068 --> 00:02:21,007 But it makes a very troubling prediction-- 42 00:02:21,040 --> 00:02:23,176 called quantum entanglement. 43 00:02:23,209 --> 00:02:27,046 ♪ ♪ 44 00:02:27,079 --> 00:02:28,814 GHOSE: Entanglement is 45 00:02:28,847 --> 00:02:31,517 this very powerful but strange connection 46 00:02:31,550 --> 00:02:34,720 that exists between pairs of particles. 47 00:02:34,753 --> 00:02:36,689 ROBBERT DIJKGRAAF: Even if they're very far apart, 48 00:02:36,722 --> 00:02:38,858 in a way, they're always coordinated. 49 00:02:38,891 --> 00:02:40,993 ♪ ♪ 50 00:02:41,026 --> 00:02:44,297 NARRATOR: Nature's fundamental building blocks could be connected 51 00:02:44,329 --> 00:02:46,966 and influence each other instantaneously, 52 00:02:46,999 --> 00:02:50,803 as if the space between them doesn't exist. 53 00:02:50,836 --> 00:02:54,173 As if two objects can mirror each other 54 00:02:54,206 --> 00:02:56,242 without any apparent connection. 55 00:02:56,275 --> 00:02:57,710 ♪ ♪ 56 00:02:57,743 --> 00:03:01,814 Einstein called it "spooky action at a distance." 57 00:03:01,847 --> 00:03:03,916 He rejected the idea 58 00:03:03,949 --> 00:03:06,285 and tried to prove it couldn't be real. 59 00:03:06,318 --> 00:03:07,653 GHOSE: You could have situations 60 00:03:07,686 --> 00:03:10,723 where the cause and the effect happen at the same time. 61 00:03:11,991 --> 00:03:15,027 NARRATOR: But if entanglement isn't real, 62 00:03:15,060 --> 00:03:17,463 cutting-edge technologies could be in jeopardy. 63 00:03:17,496 --> 00:03:20,032 KAISER: Quantum computers, quantum encryption-- 64 00:03:20,065 --> 00:03:23,269 they depend on entanglement being a fact in the world. 65 00:03:23,302 --> 00:03:24,770 ♪ ♪ 66 00:03:24,803 --> 00:03:26,038 NARRATOR: Underlying it all 67 00:03:26,071 --> 00:03:28,975 is a profound question: 68 00:03:29,008 --> 00:03:34,647 do we live in Einstein's universe of common-sense laws 69 00:03:34,680 --> 00:03:36,449 or a bizarre quantum reality 70 00:03:36,482 --> 00:03:40,418 that allows spooky connections across space and time? 71 00:03:40,452 --> 00:03:43,389 ♪ ♪ 72 00:03:52,398 --> 00:03:56,302 ♪ ♪ 73 00:04:01,240 --> 00:04:04,243 300 miles off the coast of West Africa, 74 00:04:04,276 --> 00:04:07,013 on one of the Canary Islands, 75 00:04:07,046 --> 00:04:10,483 a team of physicists is setting up a remarkable experiment 76 00:04:10,516 --> 00:04:14,687 that will use almost the entire breadth of the universe 77 00:04:14,720 --> 00:04:17,023 to settle the question, 78 00:04:17,055 --> 00:04:20,125 "Is the seemingly impossible phenomenon 79 00:04:20,159 --> 00:04:21,661 "of quantum entanglement 80 00:04:21,694 --> 00:04:23,229 "an illusion, 81 00:04:23,262 --> 00:04:26,132 or is it actually real?" 82 00:04:26,165 --> 00:04:30,303 Leading the team is Anton Zeilinger. 83 00:04:30,336 --> 00:04:36,475 ZEILINGER: So we're now going up the mountain 84 00:04:36,508 --> 00:04:39,245 towards the Roque de los Muchachos. 85 00:04:39,278 --> 00:04:42,382 So everything looks perfect today. 86 00:04:44,249 --> 00:04:45,851 NARRATOR: It's a precarious undertaking. 87 00:04:45,884 --> 00:04:48,154 They've got a short window 88 00:04:48,187 --> 00:04:51,724 on two of Europe's largest telescopes. 89 00:04:51,757 --> 00:04:56,095 Each one will simultaneously focus on a different quasar-- 90 00:04:56,128 --> 00:04:57,363 an extremely distant galaxy 91 00:04:57,396 --> 00:05:02,234 emitting huge amounts of light from its core. 92 00:05:02,267 --> 00:05:03,602 ♪ ♪ 93 00:05:03,635 --> 00:05:07,907 This light will be used to control precise equipment 94 00:05:07,940 --> 00:05:09,442 that must be perfectly aligned 95 00:05:09,475 --> 00:05:13,146 to make measurements on tiny subatomic particles. 96 00:05:13,712 --> 00:05:16,315 (speaking German): 97 00:05:16,348 --> 00:05:17,450 MAN (on radio): Okay. 98 00:05:17,483 --> 00:05:19,518 NARRATOR: And if that isn't tricky enough, 99 00:05:19,551 --> 00:05:24,090 the weather on the mountain is notoriously unpredictable. 100 00:05:24,123 --> 00:05:26,158 The team needs perfect conditions 101 00:05:26,191 --> 00:05:27,827 for the experiment to work. 102 00:05:27,860 --> 00:05:30,429 ♪ ♪ 103 00:05:30,462 --> 00:05:33,099 ZEILINGER: In the end it could be running smoothly 104 00:05:33,132 --> 00:05:37,803 or there need to be a couple of decisions made, 105 00:05:37,836 --> 00:05:41,674 you know, in an excited state in the last instant. 106 00:05:41,707 --> 00:05:45,378 ♪ ♪ 107 00:05:45,411 --> 00:05:48,814 NARRATOR: With the experiment finally set up, 108 00:05:48,847 --> 00:05:54,286 the team takes their positions. 109 00:05:54,319 --> 00:05:56,189 ♪ ♪ 110 00:05:57,689 --> 00:06:00,493 David Kaiser has worked on this experiment 111 00:06:00,526 --> 00:06:01,460 with his colleagues 112 00:06:01,493 --> 00:06:04,597 Jason Gallicchio and Andy Friedman 113 00:06:04,630 --> 00:06:06,565 for four years. 114 00:06:06,598 --> 00:06:10,536 Coordinating it all is Dominik Rauch. 115 00:06:10,569 --> 00:06:13,172 The experiment is his thesis project, 116 00:06:13,205 --> 00:06:15,007 and it's been years in the making. 117 00:06:15,040 --> 00:06:18,411 But as darkness falls, 118 00:06:18,444 --> 00:06:22,515 temperatures on the mountain begin to drop. 119 00:06:22,548 --> 00:06:27,019 MAN (speaking German, on radio): 120 00:06:27,586 --> 00:06:30,022 (speaking German) 121 00:06:30,055 --> 00:06:32,057 Okay, there's bad news. 122 00:06:32,090 --> 00:06:35,094 They have been told to leave the William Herschel 123 00:06:35,127 --> 00:06:36,595 because the road will be so dangerous, 124 00:06:36,628 --> 00:06:38,798 too dangerous, so they have to go down now. 125 00:06:38,831 --> 00:06:39,999 KAISER: Too icy? 126 00:06:40,032 --> 00:06:41,267 Yeah. 127 00:06:40,032 --> 00:06:41,267 That's okay. 128 00:06:41,300 --> 00:06:43,436 ♪ ♪ 129 00:06:46,238 --> 00:06:49,709 ♪ ♪ 130 00:06:56,915 --> 00:07:03,355 NARRATOR: The next day, the team prepares for another attempt. 131 00:07:03,388 --> 00:07:06,425 ♪ ♪ 132 00:07:06,458 --> 00:07:11,664 They verify the equipment hasn't been affected by the weather. 133 00:07:13,398 --> 00:07:19,071 But now, the air is thick with clouds. 134 00:07:24,610 --> 00:07:27,179 ZEILINGER: Here's the humidity at the various telescopes, 135 00:07:27,212 --> 00:07:30,716 and you see the humidity is 100%. 136 00:07:30,749 --> 00:07:34,987 So as long as this lasts, 137 00:07:35,020 --> 00:07:36,989 we can't do much. 138 00:07:37,022 --> 00:07:40,593 (wind whistling) 139 00:07:40,626 --> 00:07:41,961 (phone ringing) 140 00:07:41,994 --> 00:07:46,032 NARRATOR: The teams at both telescopes wait. 141 00:07:48,367 --> 00:07:51,504 But the clouds don't clear. 142 00:07:51,537 --> 00:07:56,442 All the preparation has come to nothing. 143 00:07:56,475 --> 00:08:00,312 Time on these huge telescopes is precious, 144 00:08:00,345 --> 00:08:02,281 and theirs has run out. 145 00:08:02,314 --> 00:08:05,484 This ambitious test of quantum entanglement 146 00:08:05,517 --> 00:08:08,854 must wait. 147 00:08:08,887 --> 00:08:15,361 ♪ ♪ 148 00:08:15,394 --> 00:08:17,496 Why are physicists so determined 149 00:08:17,529 --> 00:08:20,065 to put this bizarre aspect of quantum mechanics 150 00:08:20,098 --> 00:08:22,468 to the ultimate test? 151 00:08:25,337 --> 00:08:26,972 To explore the beginning of the story, 152 00:08:27,005 --> 00:08:29,308 David Kaiser has come to Brussels, 153 00:08:29,341 --> 00:08:34,246 the city that Albert Einstein traveled to in 1927 154 00:08:34,279 --> 00:08:37,515 to attend a meeting about a new theory 155 00:08:37,549 --> 00:08:41,921 that described the micro-world of atoms and tiny particles-- 156 00:08:41,953 --> 00:08:45,558 quantum mechanics. 157 00:08:45,591 --> 00:08:46,959 Quantum mechanics is one 158 00:08:46,992 --> 00:08:49,595 of the most amazing intellectual achievements in human history. 159 00:08:49,628 --> 00:08:52,131 GHOSE: For the first time, 160 00:08:52,164 --> 00:08:57,236 scientists were able to probe a world that was, until then, 161 00:08:57,269 --> 00:08:58,504 quite invisible to us. 162 00:08:58,537 --> 00:09:02,107 Looking at the world at the scale of atoms, 163 00:09:02,140 --> 00:09:06,178 a million times smaller than the width of a human hair. 164 00:09:06,211 --> 00:09:07,713 One way to think about the scales 165 00:09:07,746 --> 00:09:09,949 is that if you take an everyday object, 166 00:09:09,982 --> 00:09:14,253 like a soccer ball... 167 00:09:14,286 --> 00:09:15,821 and you enlarge that soccer ball, 168 00:09:15,854 --> 00:09:19,658 so that actually you can see the individual atoms, 169 00:09:19,691 --> 00:09:24,330 you roughly have to make it the size of the Earth. 170 00:09:24,363 --> 00:09:27,866 And then move into the planet. 171 00:09:27,899 --> 00:09:32,905 Then you are in the world of atoms and particles. 172 00:09:32,938 --> 00:09:36,241 NARRATOR: It was the nature of fundamental particles, 173 00:09:36,274 --> 00:09:39,712 which make up the world we see around us, 174 00:09:39,745 --> 00:09:42,648 that Einstein had come to Brussels to discuss. 175 00:09:42,681 --> 00:09:45,918 And it was here that Einstein entered into a heated debate 176 00:09:45,951 --> 00:09:53,258 that would lead to the discovery of quantum entanglement-- 177 00:09:53,290 --> 00:09:56,228 a concept that would trouble him for the rest of his life. 178 00:09:56,261 --> 00:09:58,564 ♪ ♪ 179 00:09:58,597 --> 00:10:02,167 David Kaiser has come to the place where it all began. 180 00:10:02,200 --> 00:10:04,837 ♪ ♪ 181 00:10:04,870 --> 00:10:08,574 KAISER: This is the original Solvay Institute building. 182 00:10:08,607 --> 00:10:10,809 Beautiful grand building. 183 00:10:10,842 --> 00:10:12,211 And this is the place, 184 00:10:12,244 --> 00:10:15,614 back in October 1927, 185 00:10:15,647 --> 00:10:17,683 where the fifth Solvay Conference was held. 186 00:10:17,716 --> 00:10:21,854 This amazing, weeklong series of discussions 187 00:10:21,887 --> 00:10:23,255 on really what the world was made of, 188 00:10:23,288 --> 00:10:26,625 on the nature of matter and the new quantum theory. 189 00:10:26,658 --> 00:10:30,963 And these steps are the very steps 190 00:10:30,996 --> 00:10:34,767 on which this famous group photograph was taken. 191 00:10:34,800 --> 00:10:36,568 It's a collection 192 00:10:36,601 --> 00:10:39,772 of the some of the most brilliant people in the world. 193 00:10:39,805 --> 00:10:42,040 Here in the front row, we see Albert Einstein, 194 00:10:42,074 --> 00:10:44,610 and the great Marie Curie and Max Planck; 195 00:10:44,643 --> 00:10:48,147 in the back row, standing, the dapper Erwin Schrödinger. 196 00:10:48,180 --> 00:10:50,282 And these sort of brash 20-year-olds, or mid-20s, 197 00:10:50,315 --> 00:10:52,751 Werner Heisenberg and Wolfgang Pauli. 198 00:10:52,784 --> 00:10:57,790 NARRATOR: These scientists were the pioneers of quantum mechanics. 199 00:10:57,823 --> 00:11:00,626 KAISER: I had a huge version of this photograph 200 00:11:00,659 --> 00:11:01,627 up on the wall, 201 00:11:01,660 --> 00:11:03,095 it was a poster in my college dorm room. 202 00:11:03,128 --> 00:11:04,897 My roommates had their favorite bands, 203 00:11:04,930 --> 00:11:07,332 and I had the 1927 Solvay Conference, 204 00:11:07,365 --> 00:11:08,767 which says a lot. 205 00:11:08,800 --> 00:11:12,171 NARRATOR: This was one of the greatest meetings of minds 206 00:11:12,204 --> 00:11:14,306 in history. 207 00:11:14,339 --> 00:11:17,042 More than half were, or would become, 208 00:11:17,075 --> 00:11:20,045 Nobel Prize winners. 209 00:11:20,078 --> 00:11:24,650 Their experiments were showing that deep inside matter, 210 00:11:24,683 --> 00:11:28,587 tiny particles-- like atoms and their orbiting electrons-- 211 00:11:28,620 --> 00:11:31,890 were not solid little spheres. 212 00:11:31,923 --> 00:11:36,862 They seemed fuzzy and undefined. 213 00:11:36,895 --> 00:11:39,498 KAISER: So this, this group here, 214 00:11:39,531 --> 00:11:40,833 these, these were the folks 215 00:11:40,866 --> 00:11:45,471 who had just been plumbing deeper and deeper and deeper 216 00:11:45,504 --> 00:11:47,873 to find what they hoped would be a bedrock 217 00:11:47,906 --> 00:11:48,907 of what the world was made of, 218 00:11:48,940 --> 00:11:50,743 and to their surprise, 219 00:11:50,776 --> 00:11:53,579 they found things less and less solid as they dug in. 220 00:11:53,612 --> 00:11:55,514 This world was not tiny little bricks 221 00:11:55,547 --> 00:11:56,749 that got smaller and smaller. 222 00:11:56,782 --> 00:12:00,285 At some point, the bricks gave way to this mush, 223 00:12:00,318 --> 00:12:02,554 and what looked like solidity, solidness, 224 00:12:02,587 --> 00:12:04,556 in fact became very confusing 225 00:12:04,589 --> 00:12:07,659 and kind of a whole new way of thinking about nature. 226 00:12:07,692 --> 00:12:10,296 ♪ ♪ 227 00:12:12,664 --> 00:12:14,900 NARRATOR: The theory of quantum mechanics presented at the meeting 228 00:12:14,933 --> 00:12:18,270 was strange. 229 00:12:18,303 --> 00:12:21,907 It said that a particle, like an electron, 230 00:12:21,940 --> 00:12:26,445 isn't physically real until it's observed-- 231 00:12:26,478 --> 00:12:30,983 measured by an instrument that can detect it. 232 00:12:31,016 --> 00:12:33,218 Before it's detected, 233 00:12:33,251 --> 00:12:35,821 instead of being a solid particle, 234 00:12:35,854 --> 00:12:39,224 an electron is just a fuzzy wave-- 235 00:12:39,257 --> 00:12:42,995 a wave of probability. 236 00:12:43,028 --> 00:12:46,298 These objects, like electrons and atoms, 237 00:12:46,331 --> 00:12:49,001 when we describe mathematically their behavior, 238 00:12:49,034 --> 00:12:50,536 the only thing we can describe 239 00:12:50,569 --> 00:12:55,507 is the probability of being at one place or another. 240 00:12:55,540 --> 00:12:56,575 CARROLL: It's like a wave 241 00:12:56,608 --> 00:12:58,477 of all those different possibilities. 242 00:12:58,510 --> 00:13:01,580 It's not that the electron is in one place or the other, 243 00:13:01,613 --> 00:13:03,282 we just don't know, 244 00:13:03,315 --> 00:13:05,617 it's that the electron really is a combination 245 00:13:05,650 --> 00:13:08,353 of every possible place it could be 246 00:13:08,386 --> 00:13:09,688 until we look at it. 247 00:13:11,156 --> 00:13:14,393 NARRATOR: Quantum mechanics only tells us the probability 248 00:13:14,426 --> 00:13:16,228 of a particle's properties, 249 00:13:16,261 --> 00:13:18,463 like location. 250 00:13:18,496 --> 00:13:21,934 The laws of nature were no longer definite statements 251 00:13:21,967 --> 00:13:24,036 about what's going to happen next. 252 00:13:24,069 --> 00:13:26,839 They were just statements about probabilities. 253 00:13:26,872 --> 00:13:29,441 And Einstein felt, "Well, that's defeat. 254 00:13:29,474 --> 00:13:33,145 "You're giving up on the heart of what physics has been, 255 00:13:33,178 --> 00:13:36,515 namely, to give a complete description of reality." 256 00:13:36,548 --> 00:13:39,518 ♪ ♪ 257 00:13:39,551 --> 00:13:41,553 NARRATOR: For Einstein, 258 00:13:41,586 --> 00:13:44,890 the idea that particles only pop into existence 259 00:13:44,923 --> 00:13:46,792 when they're observed 260 00:13:46,825 --> 00:13:50,829 is akin to magic. 261 00:13:50,862 --> 00:13:52,564 It's said he asked, 262 00:13:52,597 --> 00:13:55,267 "Do you really believe the moon is not there 263 00:13:55,300 --> 00:13:59,338 when you are not looking at it?" 264 00:13:59,371 --> 00:14:00,706 ♪ ♪ 265 00:14:00,739 --> 00:14:03,909 Outside of the formal setting of the conference... 266 00:14:03,942 --> 00:14:05,510 KAISER: Bonsoir. 267 00:14:05,543 --> 00:14:08,380 NARRATOR: ...he challenged the most vocal supporter of these ideas: 268 00:14:08,413 --> 00:14:13,619 the great Danish physicist Niels Bohr. 269 00:14:13,652 --> 00:14:16,321 KAISER: Einstein would show up to breakfast at the hotel, 270 00:14:16,354 --> 00:14:17,923 and Niels Bohr would be there, 271 00:14:17,956 --> 00:14:20,259 and Einstein would present his latest challenge. 272 00:14:20,292 --> 00:14:22,895 Niels Bohr would sort of mumble and wonder 273 00:14:22,928 --> 00:14:24,763 and confer with his younger colleagues. 274 00:14:24,796 --> 00:14:27,966 They'd head off to the formal meeting at the institute, 275 00:14:27,999 --> 00:14:31,036 and somehow, every night by suppertime, 276 00:14:31,069 --> 00:14:32,604 Bohr would have an answer. 277 00:14:32,637 --> 00:14:34,306 One of the observers said 278 00:14:34,339 --> 00:14:35,908 that Einstein was like a jack-in-the-box; 279 00:14:35,941 --> 00:14:37,809 every day, he'd pop up with a new challenge. 280 00:14:37,842 --> 00:14:40,112 And Bohr would flip this way and that, 281 00:14:40,145 --> 00:14:42,547 and in the end, by supper, have crushed that one, 282 00:14:42,580 --> 00:14:44,016 and it would start all over again. 283 00:14:46,117 --> 00:14:48,153 NARRATOR: To Bohr and his colleagues, 284 00:14:48,186 --> 00:14:52,391 quantum mechanics not only explained experimental results, 285 00:14:52,424 --> 00:14:56,461 its mathematics were elegant and beautiful. 286 00:14:56,494 --> 00:15:00,532 And since Einstein hadn't found flaws in their equations, 287 00:15:00,565 --> 00:15:04,670 they left the Solvay meeting feeling more confident than ever 288 00:15:04,703 --> 00:15:06,505 in their ideas. 289 00:15:06,538 --> 00:15:09,708 But Einstein didn't give up his conviction 290 00:15:09,741 --> 00:15:13,412 that quantum mechanics was flawed. 291 00:15:13,445 --> 00:15:15,013 And in his refusal to accept 292 00:15:15,046 --> 00:15:17,616 the weird implications of the theory, 293 00:15:17,649 --> 00:15:22,287 he would wind up uncovering something even weirder. 294 00:15:22,320 --> 00:15:23,789 ♪ ♪ 295 00:15:23,822 --> 00:15:28,860 In 1933, with the Nazi Party in power in Germany, 296 00:15:28,893 --> 00:15:31,396 Einstein chose to settle in America 297 00:15:31,429 --> 00:15:34,199 and took a position at the Institute for Advanced Study 298 00:15:34,232 --> 00:15:36,268 in Princeton, New Jersey. 299 00:15:36,301 --> 00:15:39,004 ♪ ♪ 300 00:15:39,037 --> 00:15:42,174 He recruited two physicists to help him, 301 00:15:42,207 --> 00:15:46,645 Nathan Rosen and Boris Podolsky. 302 00:15:46,678 --> 00:15:49,581 And in 1935, at afternoon tea, 303 00:15:49,614 --> 00:15:53,285 the three men spotted a possible flaw in quantum mechanics 304 00:15:53,318 --> 00:15:56,455 that would shake the very foundations of the theory. 305 00:15:58,323 --> 00:16:01,193 They noticed that the mathematics of quantum mechanics 306 00:16:01,226 --> 00:16:06,264 led to a seemingly impossible situation. 307 00:16:06,297 --> 00:16:10,869 Today, Robbert Dijkgraaf is the director of the institute. 308 00:16:10,902 --> 00:16:12,371 DIJKGRAAF: Apparently Podolsky would say, 309 00:16:12,404 --> 00:16:14,306 "Well, Professor Einstein, 310 00:16:14,339 --> 00:16:16,875 "this is very important in your arguments 311 00:16:16,908 --> 00:16:19,945 showing that quantum theory is incomplete." 312 00:16:19,978 --> 00:16:23,115 So they got this very animated discussion 313 00:16:23,148 --> 00:16:25,017 and what can happen still is, 314 00:16:25,050 --> 00:16:27,619 now you have a bunch of scientists discussing, 315 00:16:27,652 --> 00:16:31,256 and at some point, someone says, "Let's write a paper together." 316 00:16:31,289 --> 00:16:32,257 So they did. 317 00:16:32,290 --> 00:16:34,826 ♪ ♪ 318 00:16:34,859 --> 00:16:38,363 NARRATOR: Their paper, known today as EPR, 319 00:16:38,396 --> 00:16:43,235 argued that the equations of quantum mechanics 320 00:16:43,268 --> 00:16:46,738 predicted an impossible connection between particles-- 321 00:16:46,771 --> 00:16:49,108 a seemingly magical effect. 322 00:16:50,608 --> 00:16:54,212 It would be like having two particles, 323 00:16:54,245 --> 00:16:56,382 each hidden under a cup. 324 00:16:58,750 --> 00:17:01,053 Looking at one 325 00:17:01,086 --> 00:17:05,624 mysteriously causes the other to reveal itself, too, 326 00:17:05,656 --> 00:17:09,428 with matching properties. 327 00:17:10,361 --> 00:17:12,130 Quantum theory suggested 328 00:17:12,163 --> 00:17:15,934 this effect could happen in the real world, 329 00:17:15,967 --> 00:17:20,239 for example, with particles of light-- photons. 330 00:17:21,673 --> 00:17:24,776 The equations implied that a source of photons 331 00:17:24,809 --> 00:17:28,046 could create pairs in such a way 332 00:17:28,079 --> 00:17:30,315 that when we measure one, 333 00:17:30,348 --> 00:17:32,918 causing it to snap out of its fuzzy state, 334 00:17:32,951 --> 00:17:37,656 the other mysteriously snaps out of its fuzzy state 335 00:17:37,689 --> 00:17:39,491 at the same instant, 336 00:17:39,524 --> 00:17:42,027 with correlated properties. 337 00:17:47,499 --> 00:17:51,203 The 1935 paper that described this effect 338 00:17:51,236 --> 00:17:56,108 has become Einstein's most referenced work of all. 339 00:17:56,141 --> 00:18:00,212 It has captivated generations of physicists, 340 00:18:00,245 --> 00:18:03,915 including Anton Zeilinger. 341 00:18:03,948 --> 00:18:08,353 ZEILINGER: The Einstein-Podolsky-Rosen paper fascinated me. 342 00:18:08,386 --> 00:18:11,890 And I had to read it at least five or six times 343 00:18:11,923 --> 00:18:14,559 until I finally understood what goes on. 344 00:18:14,592 --> 00:18:17,562 And then it didn't let me go again. 345 00:18:17,595 --> 00:18:21,066 NARRATOR: Another way to think of the paired particles 346 00:18:21,099 --> 00:18:25,637 is to imagine a game of chance that's somehow rigged. 347 00:18:25,670 --> 00:18:30,509 Suppose I had a pair of quantum dice. 348 00:18:30,542 --> 00:18:35,947 I put these two quantum dice in my little cup, 349 00:18:35,980 --> 00:18:39,384 throw them. 350 00:18:39,417 --> 00:18:43,255 I look at them, they show the same number-- six. 351 00:18:43,288 --> 00:18:45,624 I put them again in the cup, 352 00:18:45,657 --> 00:18:48,226 throw them again. 353 00:18:48,259 --> 00:18:51,163 Now they both show three. 354 00:18:51,196 --> 00:18:55,634 I put them in again, throw again, 355 00:18:55,667 --> 00:18:58,236 now they both show one. 356 00:18:58,269 --> 00:19:01,773 Point now being, what I see here is, 357 00:19:01,806 --> 00:19:04,910 I see two random processes-- 358 00:19:04,943 --> 00:19:07,379 namely, each die showing some number-- 359 00:19:07,412 --> 00:19:13,485 but these two random processes do the same. 360 00:19:13,518 --> 00:19:15,086 It's really mind-boggling. 361 00:19:15,119 --> 00:19:16,655 ♪ ♪ 362 00:19:16,688 --> 00:19:19,891 NARRATOR: How could two particles act in unison, 363 00:19:19,924 --> 00:19:22,694 even when they're separated from each other? 364 00:19:25,129 --> 00:19:26,965 Essential to the EPR argument 365 00:19:26,998 --> 00:19:29,467 is that these particles can be, can be separated 366 00:19:29,500 --> 00:19:30,735 at an arbitrary distance. 367 00:19:30,768 --> 00:19:32,170 One could be here at Princeton, 368 00:19:32,203 --> 00:19:33,972 one could be in the Andromeda Galaxy. 369 00:19:34,005 --> 00:19:36,775 And yet, according to quantum mechanics, 370 00:19:36,808 --> 00:19:38,677 a choice to measure something here 371 00:19:38,710 --> 00:19:41,413 is somehow instantaneously affecting 372 00:19:41,446 --> 00:19:43,882 what could be said about this other particle. 373 00:19:43,915 --> 00:19:46,318 You can't go from Princeton to Andromeda instantly, 374 00:19:46,351 --> 00:19:47,819 and yet that, they argued, 375 00:19:47,852 --> 00:19:50,021 is what the equations of quantum mechanics seemed to imply, 376 00:19:50,054 --> 00:19:51,122 and that, they said, 377 00:19:51,155 --> 00:19:52,657 so much the worse for quantum mechanics. 378 00:19:52,690 --> 00:19:55,160 The world simply can't operate that way. 379 00:19:56,761 --> 00:20:00,532 NARRATOR: For Einstein, this strange effect conflicted 380 00:20:00,565 --> 00:20:04,769 with the most basic concept we use to describe reality-- 381 00:20:04,802 --> 00:20:06,471 space. 382 00:20:06,504 --> 00:20:11,643 For him, objects, particles, everything that exists 383 00:20:11,676 --> 00:20:15,747 is located in space. 384 00:20:15,780 --> 00:20:18,516 Space, together with time, 385 00:20:18,549 --> 00:20:21,753 was the key ingredient in his theory of special relativity, 386 00:20:21,786 --> 00:20:28,994 with its famous equation, E = MC squared. 387 00:20:29,027 --> 00:20:33,265 CARROLL: Einstein, of course, was the master of space-time. 388 00:20:33,298 --> 00:20:35,634 He thought that if something happened here, 389 00:20:35,667 --> 00:20:38,436 that shouldn't immediately and instantaneously 390 00:20:38,469 --> 00:20:40,338 change something that is going on over there-- 391 00:20:40,371 --> 00:20:43,242 the principle of locality, as we currently call it. 392 00:20:44,876 --> 00:20:47,812 NARRATOR: For Einstein, it's simply common sense 393 00:20:47,845 --> 00:20:51,082 that if objects are separated in space, 394 00:20:51,115 --> 00:20:53,285 for one to affect the other, 395 00:20:53,318 --> 00:20:57,355 something must travel between them. 396 00:20:57,388 --> 00:21:01,660 ♪ ♪ 397 00:21:01,693 --> 00:21:03,495 And that traveling takes time. 398 00:21:07,532 --> 00:21:11,136 Quantum particles acting in unison could be explained 399 00:21:11,169 --> 00:21:14,572 if they were communicating-- 400 00:21:14,605 --> 00:21:18,376 one particle instantly sending a signal to the other, 401 00:21:18,409 --> 00:21:22,314 telling it what properties it should have. 402 00:21:22,347 --> 00:21:24,215 But that would require a signal 403 00:21:24,248 --> 00:21:26,951 traveling faster than the speed of light, 404 00:21:26,984 --> 00:21:29,587 something Einstein's theory of special relativity 405 00:21:29,620 --> 00:21:34,125 had proven impossible. 406 00:21:34,158 --> 00:21:39,464 And it would mean the particles were fuzzy and undefined 407 00:21:39,497 --> 00:21:45,170 until the moment they were observed. 408 00:21:45,203 --> 00:21:47,138 Instead, 409 00:21:47,171 --> 00:21:50,809 Einstein thought the particles should be real all along. 410 00:21:50,842 --> 00:21:54,913 They must carry with them a hidden layer of deeper physics 411 00:21:54,946 --> 00:21:59,484 that determines their properties from the start. 412 00:21:59,517 --> 00:22:01,953 Almost the way that magic tricks, 413 00:22:01,986 --> 00:22:07,859 while appearing mysterious, have a hidden explanation. 414 00:22:07,892 --> 00:22:11,930 But this hidden physics was missing from quantum theory. 415 00:22:11,963 --> 00:22:16,401 So Einstein, Podolsky, and Rosen argued that quantum mechanics 416 00:22:16,434 --> 00:22:18,503 was incomplete. 417 00:22:18,536 --> 00:22:20,872 ♪ ♪ 418 00:22:20,905 --> 00:22:23,975 DIJKGRAAF: Podolsky was very enthusiastic about this project. 419 00:22:24,008 --> 00:22:25,744 In fact, he was so enthusiastic 420 00:22:25,777 --> 00:22:28,747 that he ran to the "New York Times" 421 00:22:28,780 --> 00:22:29,848 and told them the news. 422 00:22:29,881 --> 00:22:33,017 So Einstein was really upset with Podolsky, 423 00:22:33,050 --> 00:22:35,653 and apparently, he didn't speak to him anymore. 424 00:22:35,686 --> 00:22:37,255 ♪ ♪ 425 00:22:37,288 --> 00:22:40,158 NARRATOR: When Niels Bohr heard of Einstein's paper, 426 00:22:40,191 --> 00:22:43,528 he wrote an obscure response, 427 00:22:43,561 --> 00:22:46,631 arguing that one particle could somehow 428 00:22:46,664 --> 00:22:49,901 mysteriously influence the other. 429 00:22:49,934 --> 00:22:51,970 This seemingly impossible phenomenon 430 00:22:52,003 --> 00:22:56,708 became known as quantum entanglement. 431 00:22:58,709 --> 00:23:04,082 But Einstein dismissed it as "spooky actions at a distance." 432 00:23:05,716 --> 00:23:08,086 No one could think of an experiment to test 433 00:23:08,119 --> 00:23:13,124 whether Einstein or Bohr was correct. 434 00:23:13,157 --> 00:23:16,060 But that didn't stop physicists and engineers 435 00:23:16,093 --> 00:23:17,762 from making use of quantum mechanics 436 00:23:17,795 --> 00:23:20,899 to do new things. 437 00:23:20,932 --> 00:23:23,067 GHOSE: In the '30s and '40s, 438 00:23:23,100 --> 00:23:26,805 the debate around the EPR paper sort of dies down. 439 00:23:26,838 --> 00:23:28,706 But, quantum theory actually takes off. 440 00:23:28,739 --> 00:23:31,109 ♪ ♪ 441 00:23:31,142 --> 00:23:35,113 The mathematics leads to all kinds of amazing developments. 442 00:23:35,146 --> 00:23:37,749 NARRATOR: Entanglement aside, 443 00:23:37,782 --> 00:23:39,217 the equations of quantum mechanics 444 00:23:39,250 --> 00:23:42,554 enabled the scientists of the Manhattan Project 445 00:23:42,587 --> 00:23:45,290 to develop the atomic bomb. 446 00:23:45,323 --> 00:23:47,725 And in the years after the Second World War, 447 00:23:47,758 --> 00:23:50,462 researchers at Bell Labs in New Jersey 448 00:23:50,495 --> 00:23:53,665 used quantum theory to develop one of the first lasers... 449 00:23:53,698 --> 00:23:54,999 MAN (in film): In our laboratories, 450 00:23:55,032 --> 00:23:56,734 men experiment with a light 451 00:23:56,767 --> 00:23:59,671 once undreamed-of in the natural world. 452 00:23:59,704 --> 00:24:01,139 NARRATOR: ...and build small devices 453 00:24:01,172 --> 00:24:03,808 that could control the flow of electricity-- 454 00:24:03,841 --> 00:24:05,777 transistors. 455 00:24:05,810 --> 00:24:08,847 MAN 2 (on film): It's destined to play a vital role in your future, 456 00:24:08,880 --> 00:24:11,015 your electronic future. 457 00:24:11,048 --> 00:24:14,018 NARRATOR: Transistors became the building blocks 458 00:24:14,051 --> 00:24:16,654 of the burgeoning field of electronics. 459 00:24:16,687 --> 00:24:18,056 Computers, disc drives-- 460 00:24:18,089 --> 00:24:21,793 the entire digital revolution soon followed, 461 00:24:21,826 --> 00:24:22,794 all made possible 462 00:24:22,827 --> 00:24:26,198 by the equations of quantum theory. 463 00:24:27,198 --> 00:24:30,935 Yet Einstein's questions about entanglement 464 00:24:30,968 --> 00:24:32,070 and what it implied 465 00:24:32,103 --> 00:24:34,105 about the incompleteness of quantum mechanics 466 00:24:34,138 --> 00:24:38,776 remained unanswered until the 1960s, 467 00:24:38,809 --> 00:24:42,013 when a physicist from Northern Ireland 468 00:24:42,046 --> 00:24:44,349 made a remarkable breakthrough-- 469 00:24:44,382 --> 00:24:46,751 John Bell. 470 00:24:46,784 --> 00:24:49,454 KAISER: Bell was a very talented young physics student, 471 00:24:49,487 --> 00:24:52,190 but he quickly grew dissatisfied with what he considered almost, 472 00:24:52,223 --> 00:24:54,425 almost a kind of dishonesty among his teachers. 473 00:24:54,458 --> 00:24:55,827 (talking in background) 474 00:24:55,860 --> 00:24:57,161 NARRATOR: Bell insisted 475 00:24:57,194 --> 00:24:59,964 that Einstein's questions about quantum mechanics 476 00:24:59,997 --> 00:25:01,599 had not been addressed. 477 00:25:01,632 --> 00:25:04,369 KAISER: He got into shouting matches with his professors. 478 00:25:04,402 --> 00:25:06,671 "Don't tell us that Bohr solved all the problems. 479 00:25:06,704 --> 00:25:09,407 This really deserves further thought." 480 00:25:09,440 --> 00:25:13,144 BELL: Quantum mechanics has been fantastically successful. 481 00:25:13,177 --> 00:25:16,347 So it is a very intriguing situation 482 00:25:16,380 --> 00:25:19,083 that at the, at the foundation 483 00:25:19,116 --> 00:25:22,287 of all that impressive success, 484 00:25:22,320 --> 00:25:23,821 there are these great doubts. 485 00:25:23,854 --> 00:25:26,658 ♪ ♪ 486 00:25:26,691 --> 00:25:29,727 CARROLL: It's a very strange thing that ever since the 1930s, 487 00:25:29,760 --> 00:25:31,930 the idea of sitting and thinking hard 488 00:25:31,963 --> 00:25:33,698 about the foundations of quantum mechanics 489 00:25:33,731 --> 00:25:36,768 has been disreputable among professional physicists. 490 00:25:36,801 --> 00:25:38,436 When people tried to do that, 491 00:25:38,469 --> 00:25:40,772 they were kicked out of physics departments. 492 00:25:40,805 --> 00:25:42,607 And so, for someone like Bell, 493 00:25:42,640 --> 00:25:46,344 he needed to have a day job doing ordinary particle physics, 494 00:25:46,377 --> 00:25:48,179 but at night, you know, hidden away, 495 00:25:48,212 --> 00:25:49,247 he could do work 496 00:25:49,280 --> 00:25:50,648 on the foundations of quantum mechanics. 497 00:25:50,681 --> 00:25:54,118 NARRATOR: Bell became a leading particle physicist 498 00:25:54,151 --> 00:25:55,987 at CERN, in Geneva. 499 00:25:56,020 --> 00:25:58,222 But he continued to explore the debate 500 00:25:58,255 --> 00:26:01,426 between Einstein and Bohr. 501 00:26:01,459 --> 00:26:06,164 And in 1964, he published an astonishing paper. 502 00:26:07,865 --> 00:26:10,034 Bell proved 503 00:26:10,067 --> 00:26:14,238 that Bohr's and Einstein's ideas made different predictions. 504 00:26:14,271 --> 00:26:18,576 If you could randomly perform one of two possible measurements 505 00:26:18,609 --> 00:26:20,044 on each particle, 506 00:26:20,077 --> 00:26:24,749 and check how often the results lined up, 507 00:26:24,782 --> 00:26:27,552 the answer would reveal whether we lived in Einstein's world-- 508 00:26:27,585 --> 00:26:31,422 a world that followed common-sense laws-- 509 00:26:31,455 --> 00:26:34,892 or Bohr's-- 510 00:26:34,925 --> 00:26:37,195 a world that was deeply strange 511 00:26:37,228 --> 00:26:40,298 and allowed spooky quantum connections. 512 00:26:40,331 --> 00:26:41,566 We now know with hindsight 513 00:26:41,599 --> 00:26:43,901 this was one of the most significant articles 514 00:26:43,934 --> 00:26:45,136 in the history of physics-- 515 00:26:45,169 --> 00:26:46,938 not just the history of 20th-century physics, 516 00:26:46,971 --> 00:26:49,541 in the history of, of the field as a whole. 517 00:26:51,609 --> 00:26:54,245 But Bell's article appears in this, you know, 518 00:26:54,278 --> 00:26:55,480 sort of out-of-the-way journal-- 519 00:26:55,513 --> 00:26:57,882 in fact, the journal itself folds a few years later. 520 00:26:57,915 --> 00:27:00,385 This is not central to the physics community. 521 00:27:00,418 --> 00:27:03,254 It's sort of dutifully filed on library shelves 522 00:27:03,287 --> 00:27:04,355 and then forgotten. 523 00:27:04,388 --> 00:27:06,891 It literally collects dust on the shelf. 524 00:27:06,924 --> 00:27:11,963 NARRATOR: A few years later, completely by chance, 525 00:27:11,996 --> 00:27:13,631 a brilliant experimental physicist 526 00:27:13,664 --> 00:27:16,768 stumbled upon Bell's article. 527 00:27:16,801 --> 00:27:19,904 JOHN CLAUSER: I thought this is one of the most amazing papers 528 00:27:19,937 --> 00:27:23,041 I had ever read in my whole life. 529 00:27:23,074 --> 00:27:26,711 And I kept wondering, "Well, gee, this is wonderful, 530 00:27:26,744 --> 00:27:29,514 but where's the experimental evidence?" 531 00:27:29,547 --> 00:27:32,083 NARRATOR: John worked on Bell's theory 532 00:27:32,116 --> 00:27:33,918 with fellow physicist Abner Shimony, 533 00:27:33,951 --> 00:27:37,088 and at the University of California, Berkeley, 534 00:27:37,121 --> 00:27:40,191 started work on an experiment to test it. 535 00:27:40,224 --> 00:27:44,062 He had a talent for tinkering in the lab 536 00:27:44,095 --> 00:27:45,496 and building the parts he needed. 537 00:27:45,529 --> 00:27:46,964 CLAUSER: I used to rummage around here 538 00:27:46,997 --> 00:27:49,867 and scavenge and dumpster-dive for old equipment. 539 00:27:49,900 --> 00:27:54,172 NARRATOR: He knew where to find hidden storage rooms, like this, 540 00:27:54,205 --> 00:27:57,241 which he could raid to salvage spare parts 541 00:27:57,274 --> 00:27:59,544 for his experiments. 542 00:27:59,577 --> 00:28:02,346 (grunts) 543 00:28:02,379 --> 00:28:07,251 CLAUSER: This was a power supply for diode lasers. 544 00:28:07,284 --> 00:28:09,387 That looks like something I built. 545 00:28:09,420 --> 00:28:12,657 ♪ ♪ 546 00:28:12,690 --> 00:28:15,259 Here is a picture of the experiment I did. 547 00:28:15,292 --> 00:28:19,130 (chuckling): I had more hair in those days. 548 00:28:19,163 --> 00:28:20,665 Here's another picture. 549 00:28:20,698 --> 00:28:22,333 This is of Stu Freedman, 550 00:28:22,366 --> 00:28:24,602 who worked on it with me. 551 00:28:24,635 --> 00:28:29,540 NARRATOR: Piece by piece, John Clauser and Stuart Freedman 552 00:28:29,573 --> 00:28:32,877 constructed the world's first Bell test experiment. 553 00:28:32,910 --> 00:28:37,014 They focused a laser onto calcium atoms, 554 00:28:37,047 --> 00:28:40,051 causing them to emit pairs of photons 555 00:28:40,084 --> 00:28:42,987 that the equations of quantum theory suggested 556 00:28:43,020 --> 00:28:45,990 should be entangled. 557 00:28:46,023 --> 00:28:48,726 They recorded whether or not the photons passed 558 00:28:48,759 --> 00:28:51,662 through filters on each side 559 00:28:51,695 --> 00:28:56,200 and checked how often the answers agreed. 560 00:28:56,233 --> 00:28:58,870 After hundreds of thousands of measurements, 561 00:28:58,903 --> 00:29:00,638 if the pairs were more correlated 562 00:29:00,671 --> 00:29:03,307 than Einstein's physics predicted, 563 00:29:03,340 --> 00:29:08,579 they must be spookily entangled. 564 00:29:08,612 --> 00:29:10,481 We saw the stronger correlation 565 00:29:10,514 --> 00:29:12,150 characteristic of quantum mechanics. 566 00:29:12,183 --> 00:29:16,087 We measured it, and that is what we got. 567 00:29:16,120 --> 00:29:17,855 ♪ ♪ 568 00:29:17,888 --> 00:29:19,023 NARRATOR: The outcome was exactly 569 00:29:19,056 --> 00:29:22,560 what Bohr's quantum mechanics predicted. 570 00:29:22,593 --> 00:29:25,530 The experiment appeared to show 571 00:29:25,563 --> 00:29:28,332 that the spooky connections of quantum entanglement 572 00:29:28,365 --> 00:29:31,469 did exist in the natural world. 573 00:29:31,502 --> 00:29:38,910 Could it be that the great Albert Einstein was wrong? 574 00:29:38,943 --> 00:29:40,711 Remarkably, 575 00:29:40,744 --> 00:29:44,982 the first people to react to this extraordinary result 576 00:29:45,015 --> 00:29:48,085 were not the world's leading physicists. 577 00:29:48,118 --> 00:29:51,656 ♪ ♪ 578 00:29:51,689 --> 00:29:54,692 CLAUSER: Ronald Reagan's definition of a hippie 579 00:29:54,725 --> 00:29:58,596 was someone who dresses like Tarzan, 580 00:29:58,629 --> 00:29:59,831 has hair like Jane, 581 00:29:59,864 --> 00:30:02,099 and smells like Cheeta. 582 00:30:02,132 --> 00:30:02,767 (laughs) 583 00:30:02,800 --> 00:30:06,003 ♪ ♪ 584 00:30:06,036 --> 00:30:09,073 NARRATOR: A small group of free-thinking physicists 585 00:30:09,106 --> 00:30:12,577 at the heart of San Francisco's New Age scene 586 00:30:12,610 --> 00:30:15,379 got in touch with John. 587 00:30:15,412 --> 00:30:18,449 KAISER: They called themselves the Fundamental Fysiks Group. 588 00:30:18,482 --> 00:30:20,351 They spelled physics with an F. 589 00:30:20,384 --> 00:30:23,454 Some members would experiment with psychedelic drugs. 590 00:30:23,487 --> 00:30:25,456 I mean, they were, they were kind of in the flow 591 00:30:25,489 --> 00:30:26,791 of the kind of hippie scene. 592 00:30:26,824 --> 00:30:29,193 And that group was just mesmerized 593 00:30:29,226 --> 00:30:30,394 by the question of entanglement. 594 00:30:30,427 --> 00:30:33,264 ♪ ♪ 595 00:30:33,297 --> 00:30:36,234 CLAUSER: The idea was just to discuss fringe subjects 596 00:30:36,267 --> 00:30:37,401 with an open mind. 597 00:30:37,434 --> 00:30:38,736 And I thought, "Oh, sure! 598 00:30:38,769 --> 00:30:40,838 Uh, that's kind of what I do." 599 00:30:40,871 --> 00:30:42,874 ♪ ♪ 600 00:30:42,907 --> 00:30:47,578 They were doing their best to link Eastern mysticism 601 00:30:47,611 --> 00:30:50,147 with quantum entanglement. 602 00:30:50,180 --> 00:30:52,717 They sold a lot of popular textbooks. 603 00:30:52,750 --> 00:30:55,019 There were a lot of followers. 604 00:30:55,052 --> 00:30:57,455 NARRATOR: Their books became bestsellers, 605 00:30:57,488 --> 00:31:01,592 like "The Tao of Physics," which highlighted 606 00:31:01,625 --> 00:31:03,461 that Eastern philosophy and quantum entanglement 607 00:31:03,494 --> 00:31:06,430 both described a deep connectedness 608 00:31:06,463 --> 00:31:09,000 of things in the universe. 609 00:31:09,033 --> 00:31:11,135 It was the great cosmic oneness. 610 00:31:11,168 --> 00:31:17,074 NARRATOR: The group held meetings at the iconic Esalen Institute. 611 00:31:17,107 --> 00:31:19,944 CLAUSER: It was a marvelous, beautiful place 612 00:31:19,977 --> 00:31:21,979 where they would discuss all of these ideas. 613 00:31:22,012 --> 00:31:25,049 It was right on the Pacific Coast 614 00:31:25,082 --> 00:31:26,984 with the overflow from the hot tubs 615 00:31:27,017 --> 00:31:30,321 cascading down the cliffs into the Pacific Ocean. 616 00:31:30,354 --> 00:31:33,324 To my knowledge, 617 00:31:33,357 --> 00:31:36,961 no useful connections to Eastern mysticism 618 00:31:36,994 --> 00:31:38,729 were ever discovered by the group. 619 00:31:38,762 --> 00:31:41,332 ♪ ♪ 620 00:31:41,365 --> 00:31:43,234 (chuckles): But it was fun. 621 00:31:44,702 --> 00:31:46,437 NARRATOR: The Fundamental Fysiks Group 622 00:31:46,470 --> 00:31:50,308 may not have uncovered the secrets of "cosmic oneness," 623 00:31:50,341 --> 00:31:54,278 but in seeing entanglement as central to physics, 624 00:31:54,311 --> 00:32:00,351 they were decades ahead of their time. 625 00:32:00,384 --> 00:32:04,689 ♪ ♪ 626 00:32:04,722 --> 00:32:06,524 40 years later, 627 00:32:06,557 --> 00:32:08,893 cutting-edge labs around the world 628 00:32:08,926 --> 00:32:11,963 are now racing to harness quantum entanglement 629 00:32:11,996 --> 00:32:15,866 to create revolutionary new technologies... 630 00:32:15,899 --> 00:32:18,569 ♪ ♪ 631 00:32:18,602 --> 00:32:22,006 ...like quantum computers. 632 00:32:22,039 --> 00:32:24,308 ♪ ♪ 633 00:32:24,341 --> 00:32:25,676 GHOSE: In our everyday computers, 634 00:32:25,709 --> 00:32:29,080 the fundamental unit of computing is a bit, 635 00:32:29,113 --> 00:32:31,148 a binary digit-- zero or one. 636 00:32:31,181 --> 00:32:33,884 And inside the computer, there's all these transistors, 637 00:32:33,917 --> 00:32:35,619 which are turning on and off currents. 638 00:32:35,652 --> 00:32:37,855 On is one, off is zero, 639 00:32:37,888 --> 00:32:41,559 and these combinations lead to universal computing. 640 00:32:41,592 --> 00:32:43,094 With a quantum computer, 641 00:32:43,127 --> 00:32:44,428 you start with a fundamental unit 642 00:32:44,461 --> 00:32:47,098 that's not a bit, but a quantum bit, 643 00:32:47,131 --> 00:32:49,667 which is not really a zero or a one, 644 00:32:49,700 --> 00:32:50,701 but it can be fluid. 645 00:32:50,734 --> 00:32:52,803 ♪ ♪ 646 00:32:52,836 --> 00:32:57,808 NARRATOR: A quantum bit makes use of the fuzziness of the quantum world. 647 00:32:57,841 --> 00:32:59,343 A qubit, as it's known, 648 00:32:59,376 --> 00:33:04,648 can be zero or one, or a combination of both. 649 00:33:04,681 --> 00:33:07,284 A particle or tiny quantum system 650 00:33:07,317 --> 00:33:09,453 can be made into a qubit. 651 00:33:09,486 --> 00:33:11,689 And today, it's not just pairs of particles 652 00:33:11,722 --> 00:33:13,891 that can be entangled. 653 00:33:13,924 --> 00:33:17,228 Groups of qubits can be linked with entanglement 654 00:33:17,261 --> 00:33:19,730 to create a quantum computer. 655 00:33:19,763 --> 00:33:21,832 ♪ ♪ 656 00:33:21,865 --> 00:33:25,503 The more qubits, the greater the processing power. 657 00:33:25,536 --> 00:33:27,805 ♪ ♪ 658 00:33:27,838 --> 00:33:31,842 At Google's quantum computing laboratory in Santa Barbara, 659 00:33:31,875 --> 00:33:35,212 the team has recently succeeded in creating a tiny chip 660 00:33:35,245 --> 00:33:39,116 that holds an array of 72 qubits. 661 00:33:39,149 --> 00:33:41,685 ♪ ♪ 662 00:33:41,718 --> 00:33:43,821 The task for researcher Marissa Giustina 663 00:33:43,854 --> 00:33:45,022 and her colleagues 664 00:33:45,055 --> 00:33:49,827 is to send signals to these microscopic qubits 665 00:33:49,860 --> 00:33:54,165 to control and entangle them. 666 00:33:54,198 --> 00:33:56,901 GIUSTINA: Mounted on the underside of this plate, 667 00:33:56,934 --> 00:33:58,836 we have the quantum processing chip itself, 668 00:33:58,869 --> 00:34:01,272 in essence, a quantum playground, 669 00:34:01,305 --> 00:34:02,273 you could say. 670 00:34:02,306 --> 00:34:05,543 Each qubit is a quantum object 671 00:34:05,576 --> 00:34:09,179 that we should be able to control at will. 672 00:34:09,213 --> 00:34:11,815 Thinking about it as... 673 00:34:11,849 --> 00:34:15,085 "the faster version of that PC over there" 674 00:34:15,119 --> 00:34:18,089 would be a great slight to this. 675 00:34:18,121 --> 00:34:19,757 It can be much more than that. 676 00:34:21,692 --> 00:34:24,228 NARRATOR: By using entangled qubits, 677 00:34:24,261 --> 00:34:27,164 quantum computers could tackle real-world problems 678 00:34:27,197 --> 00:34:31,002 that traditional computers simply can't cope with. 679 00:34:32,735 --> 00:34:34,205 For example, 680 00:34:34,237 --> 00:34:36,674 a salesman has to travel to several cities 681 00:34:36,706 --> 00:34:40,143 and wants to find the shortest route. 682 00:34:40,177 --> 00:34:43,313 Sounds easy. 683 00:34:43,347 --> 00:34:45,181 But with just 30 cities, 684 00:34:45,215 --> 00:34:47,650 there are so many possible routes 685 00:34:47,684 --> 00:34:49,719 that it would take an ordinary computer, 686 00:34:49,753 --> 00:34:51,222 even a powerful one, 687 00:34:51,255 --> 00:34:54,592 hundreds of years to try each one 688 00:34:54,625 --> 00:34:57,261 and find the shortest. 689 00:34:57,294 --> 00:34:59,763 But with a handful of entangled qubits, 690 00:34:59,796 --> 00:35:03,100 a quantum computer could resolve the optimal path 691 00:35:03,133 --> 00:35:06,504 in a fraction of the number of steps. 692 00:35:08,739 --> 00:35:12,276 There's another reason teams like Marissa's are racing 693 00:35:12,309 --> 00:35:14,578 to create a powerful quantum computer-- 694 00:35:14,611 --> 00:35:18,649 cracking secret codes. 695 00:35:18,682 --> 00:35:21,085 In today's world, everything from online shopping 696 00:35:21,118 --> 00:35:24,388 to covert military communications 697 00:35:24,421 --> 00:35:28,692 is protected from hackers using secure digital codes, 698 00:35:28,725 --> 00:35:34,031 a process called encryption. 699 00:35:34,064 --> 00:35:37,735 But what if hackers could get hold 700 00:35:37,768 --> 00:35:39,837 of quantum computers? 701 00:35:39,870 --> 00:35:41,172 GHOSE: A quantum computer 702 00:35:41,205 --> 00:35:43,841 could crack our best encryption protocols 703 00:35:43,874 --> 00:35:45,075 in minutes, 704 00:35:45,108 --> 00:35:46,410 whereas a regular computer, 705 00:35:46,443 --> 00:35:48,512 or even a super-computing network today, 706 00:35:48,545 --> 00:35:50,982 couldn't do it, you know, given months of time. 707 00:35:52,382 --> 00:35:54,885 NARRATOR: But while quantum entanglement may be a threat 708 00:35:54,918 --> 00:35:56,787 to traditional encryption, 709 00:35:56,820 --> 00:36:01,425 it also offers an even more secure alternative-- 710 00:36:01,458 --> 00:36:06,030 a communication system that the very laws of physics 711 00:36:06,063 --> 00:36:08,499 protect from secret hacking. 712 00:36:08,532 --> 00:36:11,335 ♪ ♪ 713 00:36:12,803 --> 00:36:17,141 Researchers in China are leading the way. 714 00:36:17,174 --> 00:36:19,543 Here in Shanghai, 715 00:36:19,576 --> 00:36:23,347 at the University of Science and Technology, 716 00:36:23,380 --> 00:36:29,486 Jian-Wei Pan runs a leading quantum research center. 717 00:36:29,519 --> 00:36:31,055 His teams are working to harness 718 00:36:31,088 --> 00:36:35,125 the properties of the quantum world. 719 00:36:35,158 --> 00:36:39,964 They can send secret messages using a stream of photons 720 00:36:39,997 --> 00:36:42,533 in a system that instantly detects 721 00:36:42,566 --> 00:36:45,803 any attempt to eavesdrop. 722 00:36:46,903 --> 00:36:48,672 Jian-Wei's team 723 00:36:48,705 --> 00:36:51,442 has created a network of optical fibers 724 00:36:51,475 --> 00:36:53,344 more than a thousand miles long 725 00:36:53,377 --> 00:36:55,879 that can carry secure information 726 00:36:55,912 --> 00:36:58,816 from Beijing to Shanghai. 727 00:36:58,849 --> 00:37:03,120 It is used by banks and data companies. 728 00:37:03,153 --> 00:37:07,625 But there's a limit to how far quantum signals can be sent 729 00:37:07,658 --> 00:37:10,761 through optical fibers. 730 00:37:10,794 --> 00:37:12,096 To send signals further, 731 00:37:12,129 --> 00:37:14,365 Jian-Wei's team launched 732 00:37:14,398 --> 00:37:18,669 the world's first quantum communication satellite. 733 00:37:21,104 --> 00:37:25,576 Above Earth's atmosphere, there are fewer obstacles, 734 00:37:25,609 --> 00:37:29,780 and quantum particles can travel much further. 735 00:37:29,813 --> 00:37:33,183 ♪ ♪ 736 00:37:33,216 --> 00:37:37,521 Each night, teams on the ground prepare to track the satellite 737 00:37:37,554 --> 00:37:39,456 across the sky. 738 00:37:39,489 --> 00:37:43,193 ♪ ♪ 739 00:37:43,226 --> 00:37:45,796 Laser guidance equipment locks on 740 00:37:45,829 --> 00:37:49,767 and allows signals to be sent and received. 741 00:37:49,800 --> 00:37:52,836 The team aims to use this equipment 742 00:37:52,869 --> 00:37:56,140 to create a new, secure communication system 743 00:37:56,173 --> 00:37:58,976 using quantum entanglement. 744 00:38:01,712 --> 00:38:03,914 The satellite sends entangled photons 745 00:38:03,947 --> 00:38:05,616 to two users. 746 00:38:05,649 --> 00:38:09,887 An eavesdropper could intercept one of the entangled photons, 747 00:38:09,920 --> 00:38:15,125 measure it, and send on a replacement photon. 748 00:38:15,158 --> 00:38:17,961 But it wouldn't be an entangled photon-- 749 00:38:17,994 --> 00:38:20,164 its properties wouldn't match. 750 00:38:20,197 --> 00:38:24,768 It would be clear an eavesdropper was on the line. 751 00:38:24,801 --> 00:38:26,603 In theory, this technique could be used 752 00:38:26,636 --> 00:38:30,541 to create a totally secure global communication network. 753 00:38:30,574 --> 00:38:32,276 PAN: So the next step is, 754 00:38:32,309 --> 00:38:35,279 we will have ground station, for example, in Canada, 755 00:38:35,312 --> 00:38:38,349 and also in Africa and many countries. 756 00:38:38,382 --> 00:38:40,617 So, we will use our satellite 757 00:38:40,650 --> 00:38:43,020 for the global quantum communication. 758 00:38:43,053 --> 00:38:46,757 We want to push this technology as far as possible. 759 00:38:48,024 --> 00:38:49,526 NARRATOR: These are the first steps 760 00:38:49,559 --> 00:38:52,696 in creating a completely unhackable quantum internet 761 00:38:52,729 --> 00:38:54,031 of the future-- 762 00:38:54,064 --> 00:38:58,802 made possible by quantum entanglement. 763 00:38:58,835 --> 00:39:01,004 But there's a problem. 764 00:39:01,037 --> 00:39:03,874 What if quantum entanglement-- 765 00:39:03,907 --> 00:39:06,744 "spooky action at a distance"-- 766 00:39:06,777 --> 00:39:08,612 isn't real after all? 767 00:39:10,580 --> 00:39:12,950 It could mean entangled photons are not the path 768 00:39:12,983 --> 00:39:16,253 to complete security. 769 00:39:16,286 --> 00:39:17,521 The question goes back 770 00:39:17,554 --> 00:39:21,725 to Clauser and Freedman's Bell test experiment. 771 00:39:21,758 --> 00:39:23,560 ♪ ♪ 772 00:39:23,593 --> 00:39:26,196 In the years after their pioneering work, 773 00:39:26,229 --> 00:39:29,099 physicists began to test possible loopholes 774 00:39:29,132 --> 00:39:32,403 in their experiment-- 775 00:39:32,436 --> 00:39:34,838 ways in which the illusion of entanglement 776 00:39:34,871 --> 00:39:37,307 might be created, 777 00:39:37,340 --> 00:39:41,345 so the effect might not be so spooky after all. 778 00:39:41,378 --> 00:39:45,783 One loophole is especially hard to rule out. 779 00:39:47,150 --> 00:39:51,321 In modern Bell test experiments, devices at each side test 780 00:39:51,354 --> 00:39:54,792 whether the photons can pass through one of two filters 781 00:39:54,825 --> 00:39:57,161 that are randomly chosen, 782 00:39:57,194 --> 00:40:00,030 effectively asking one of two questions 783 00:40:00,063 --> 00:40:04,034 and checking how often the answers agree. 784 00:40:04,067 --> 00:40:06,203 After thousands of photons, 785 00:40:06,236 --> 00:40:08,372 if the results show more agreement 786 00:40:08,405 --> 00:40:10,808 than Einstein's physics predicts, 787 00:40:10,841 --> 00:40:16,413 the particles must be spookily entangled. 788 00:40:16,446 --> 00:40:17,548 But what if something 789 00:40:17,581 --> 00:40:20,484 had mysteriously influenced the equipment 790 00:40:20,517 --> 00:40:23,287 so that the choices of the filters 791 00:40:23,320 --> 00:40:26,490 were not truly random? 792 00:40:26,523 --> 00:40:28,625 KAISER: Is there any common cause, 793 00:40:28,658 --> 00:40:32,162 deep in the past, before you even turn on your device, 794 00:40:32,195 --> 00:40:34,531 that could have nudged the questions to be asked 795 00:40:34,564 --> 00:40:36,300 and the types of particles to be emitted? 796 00:40:36,333 --> 00:40:38,368 Maybe some strange particle, 797 00:40:38,401 --> 00:40:41,205 maybe some force that had not been taken into account, 798 00:40:41,238 --> 00:40:42,706 so that what looks like entanglement 799 00:40:42,739 --> 00:40:45,108 might indeed be an accident, an illusion. 800 00:40:45,141 --> 00:40:48,278 Maybe the world still acts like Einstein thought. 801 00:40:48,311 --> 00:40:52,216 ♪ ♪ 802 00:40:52,249 --> 00:40:53,517 NARRATOR: It is this loophole 803 00:40:53,550 --> 00:40:56,286 that the team at the high-altitude observatory 804 00:40:56,319 --> 00:40:57,421 in the Canary Islands 805 00:40:57,454 --> 00:41:00,357 is working to tackle. 806 00:41:00,390 --> 00:41:04,294 ♪ ♪ 807 00:41:04,327 --> 00:41:08,699 With quantum mechanics now more established than ever, 808 00:41:08,732 --> 00:41:11,235 they're determined to put entanglement 809 00:41:11,268 --> 00:41:12,769 to the ultimate test, 810 00:41:12,802 --> 00:41:15,372 and finally settle the Einstein-Bohr debate 811 00:41:15,405 --> 00:41:17,040 beyond all reasonable doubt. 812 00:41:17,073 --> 00:41:21,044 The team is creating a giant version 813 00:41:21,077 --> 00:41:23,146 of Clauser and Freedman's Bell test, 814 00:41:23,179 --> 00:41:26,951 with the entire universe as their lab bench. 815 00:41:29,219 --> 00:41:33,290 In this "cosmic Bell test," 816 00:41:33,323 --> 00:41:36,193 the source of the entangled particles 817 00:41:36,226 --> 00:41:40,631 is about a third of a mile from each of the detectors. 818 00:41:40,664 --> 00:41:44,134 The team must send perfectly timed pairs of photons 819 00:41:44,167 --> 00:41:46,970 through the air to each side. 820 00:41:47,003 --> 00:41:50,173 At the same time, the telescopes will collect light 821 00:41:50,206 --> 00:41:54,211 from two extremely far-off, extremely bright galaxies 822 00:41:54,244 --> 00:41:56,246 called quasars. 823 00:41:56,279 --> 00:41:59,283 These are among the brightest objects in the sky, 824 00:41:59,316 --> 00:42:02,886 emitting light in powerful jets. 825 00:42:02,919 --> 00:42:05,355 Random variations in this light 826 00:42:05,388 --> 00:42:07,224 will control which filters are used 827 00:42:07,257 --> 00:42:09,927 to measure the photon pairs. 828 00:42:09,960 --> 00:42:13,063 And since the quasars are so far away-- 829 00:42:13,096 --> 00:42:15,732 the light has been traveling for billions of years 830 00:42:15,765 --> 00:42:17,734 to reach Earth-- 831 00:42:17,767 --> 00:42:19,570 it makes it incredibly unlikely 832 00:42:19,603 --> 00:42:22,306 that anything could be influencing the random nature 833 00:42:22,339 --> 00:42:25,175 of the test. 834 00:42:26,943 --> 00:42:29,046 If the experiment is successful, 835 00:42:29,079 --> 00:42:30,647 the team will have tackled the loophole 836 00:42:30,680 --> 00:42:33,283 and shown that quantum entanglement 837 00:42:33,316 --> 00:42:36,053 is as spooky as Bohr always claimed. 838 00:42:36,086 --> 00:42:40,257 Dominik and Jason are at one telescope. 839 00:42:40,290 --> 00:42:41,558 Hello, Anton. 840 00:42:41,591 --> 00:42:45,362 NARRATOR: Anton is at the other. 841 00:42:45,395 --> 00:42:48,699 (speaking German): 842 00:42:48,732 --> 00:42:51,134 ZEILINGER (speaking German on phone): 843 00:42:51,167 --> 00:42:53,604 RAUCH (speaking German): 844 00:42:54,237 --> 00:42:57,274 (both speaking German) 845 00:42:57,307 --> 00:43:02,746 ♪ ♪ 846 00:43:02,779 --> 00:43:05,983 NARRATOR: With clear skies finally overhead, 847 00:43:06,016 --> 00:43:08,852 the huge telescopes awaken... 848 00:43:08,885 --> 00:43:11,655 ♪ ♪ 849 00:43:15,258 --> 00:43:17,995 ...poised to collect light from distant quasars. 850 00:43:18,028 --> 00:43:22,232 ♪ ♪ 851 00:43:22,265 --> 00:43:23,300 Moving. 852 00:43:23,333 --> 00:43:25,535 MAN (speaking German on radio): 853 00:43:25,568 --> 00:43:26,536 MAN 2: All right. 854 00:43:26,569 --> 00:43:27,704 Dark count level. 855 00:43:27,737 --> 00:43:29,272 MAN (on radio): Okay, this is good. 856 00:43:29,305 --> 00:43:31,274 RAUCH: So we're doing everything... 857 00:43:31,307 --> 00:43:33,310 ...everything at once now. 858 00:43:33,343 --> 00:43:34,611 So the guys for the links 859 00:43:34,644 --> 00:43:37,347 are setting the state of the entangled photon pair. 860 00:43:37,380 --> 00:43:39,182 We're trying to acquire the quasar. 861 00:43:39,215 --> 00:43:42,285 We're just centering it 862 00:43:42,318 --> 00:43:44,354 and making the field of view as small as possible, 863 00:43:44,387 --> 00:43:46,623 to be sure that we only have the quasar. 864 00:43:46,656 --> 00:43:47,658 Okay. 865 00:43:47,691 --> 00:43:48,925 It's guiding now? 866 00:43:47,691 --> 00:43:48,925 Yes. 867 00:43:48,958 --> 00:43:49,960 Let's wait for one more image. 868 00:43:49,993 --> 00:43:51,395 Okay. 869 00:43:49,993 --> 00:43:51,395 Of this one. 870 00:43:51,428 --> 00:43:52,429 MAN: All right. 871 00:43:52,462 --> 00:43:55,365 Great, great, great, great, great. 872 00:43:55,398 --> 00:43:56,767 Yeah, that's good. 873 00:43:57,300 --> 00:43:58,735 Looks like, 90, 874 00:43:58,768 --> 00:44:01,739 let's say 91 to be conservative, of purity. 875 00:44:03,440 --> 00:44:05,642 NARRATOR: With the telescopes now locked on 876 00:44:05,675 --> 00:44:08,412 to two different quasars, 877 00:44:08,445 --> 00:44:10,547 the team begins to take readings. 878 00:44:10,580 --> 00:44:13,350 MAN (on radio): The red counts, 12,000. 879 00:44:13,383 --> 00:44:15,485 Blue counts, 7,000. 880 00:44:15,518 --> 00:44:18,422 ♪ ♪ 881 00:44:23,493 --> 00:44:26,863 We did a full, the full cosmic Bell test. 882 00:44:26,896 --> 00:44:28,331 MAN: What? 883 00:44:28,364 --> 00:44:30,067 Yeah, we're doing a full cosmic Bell test. 884 00:44:31,367 --> 00:44:32,936 NARRATOR: It's working. 885 00:44:32,969 --> 00:44:37,074 Light from the quasars is selecting which filters are used 886 00:44:37,107 --> 00:44:41,745 to measure the entangled photons. 887 00:44:41,778 --> 00:44:43,413 RAUCH: It is exciting. 888 00:44:43,446 --> 00:44:44,514 It is. 889 00:44:44,547 --> 00:44:45,882 Now we do have a test, 890 00:44:45,915 --> 00:44:49,286 but it's not clear what the outcome will be. 891 00:44:49,319 --> 00:44:51,988 ♪ ♪ 892 00:44:52,021 --> 00:44:53,056 MAN: Moving. 893 00:44:53,089 --> 00:44:56,693 (man talking indistinctly on radio) 894 00:44:56,726 --> 00:44:58,128 MAN: All right. 895 00:44:58,161 --> 00:45:02,032 Everything is exactly the same, beautiful, perfect, yeah. 896 00:45:02,065 --> 00:45:04,168 ♪ ♪ 897 00:45:17,013 --> 00:45:20,317 ♪ ♪ 898 00:45:20,350 --> 00:45:22,219 NARRATOR: Two months later, back in Vienna, 899 00:45:22,252 --> 00:45:26,022 the team analyzes the experimental data. 900 00:45:26,055 --> 00:45:29,426 RAUCH: This might take a second. 901 00:45:30,927 --> 00:45:33,063 The numbers look really great. 902 00:45:33,096 --> 00:45:35,132 And it is extremely pleasing to see 903 00:45:35,165 --> 00:45:37,534 that all this worked so nice. 904 00:45:37,567 --> 00:45:39,903 We clearly see correlations 905 00:45:39,936 --> 00:45:41,304 that correspond to quantum mechanics. 906 00:45:41,337 --> 00:45:44,708 NARRATOR: The results show entanglement. 907 00:45:44,741 --> 00:45:47,711 ♪ ♪ 908 00:45:47,744 --> 00:45:49,713 And since the light from the quasars 909 00:45:49,746 --> 00:45:50,881 controlling the test 910 00:45:50,914 --> 00:45:54,384 was nearly eight billion years old, 911 00:45:54,417 --> 00:45:55,786 it's extremely unlikely 912 00:45:55,819 --> 00:45:59,756 that anything could have affected its random nature. 913 00:45:59,789 --> 00:46:04,661 This remaining loophole seems to be closed. 914 00:46:04,694 --> 00:46:08,031 ZEILINGER: The experiment we did is just fantastic. 915 00:46:08,064 --> 00:46:10,133 The big cosmos comes down 916 00:46:10,166 --> 00:46:13,303 to control a small quantum experiment. 917 00:46:13,336 --> 00:46:16,940 That, that in itself is a, is, is beautiful. 918 00:46:16,973 --> 00:46:21,611 ♪ ♪ 919 00:46:21,644 --> 00:46:24,414 You know, honestly, I still, I still get chills. 920 00:46:24,447 --> 00:46:26,216 I mean... 921 00:46:26,249 --> 00:46:27,584 ...when I realize what our team was able to do, 922 00:46:27,617 --> 00:46:30,821 in this intellectual journey that stretches back 923 00:46:30,854 --> 00:46:33,223 to the early years of the 20th century. 924 00:46:33,256 --> 00:46:36,326 There's, there's hardly any room left 925 00:46:36,359 --> 00:46:41,131 for a kind of alternative, Einstein-like explanation. 926 00:46:41,164 --> 00:46:42,465 We haven't ruled it out, 927 00:46:42,498 --> 00:46:45,635 but we've shoved it into such a tiny corner of the cosmos 928 00:46:45,668 --> 00:46:48,972 as to make it even more implausible 929 00:46:49,005 --> 00:46:51,208 for anything other than entanglement 930 00:46:51,241 --> 00:46:52,475 to explain our results. 931 00:46:52,508 --> 00:46:55,879 ♪ ♪ 932 00:46:55,912 --> 00:46:58,048 NARRATOR: Accepting that entanglement is a part 933 00:46:58,081 --> 00:47:00,684 of the natural world around us 934 00:47:00,717 --> 00:47:04,187 has profound implications. 935 00:47:04,220 --> 00:47:06,489 It means we must accept that an action in one place 936 00:47:06,522 --> 00:47:10,060 can have an instant effect anywhere in the universe, 937 00:47:10,093 --> 00:47:13,430 as if there's no space between them. 938 00:47:13,463 --> 00:47:18,401 Or that particles only take on physical properties 939 00:47:18,434 --> 00:47:22,105 when we observe them. 940 00:47:22,138 --> 00:47:25,041 Or we must accept both. 941 00:47:25,074 --> 00:47:27,377 We're left with conclusions about the universe 942 00:47:27,410 --> 00:47:29,145 that make no sense whatsoever. 943 00:47:29,178 --> 00:47:32,315 Science is stepping outside of all of our boundaries 944 00:47:32,348 --> 00:47:34,451 of common sense. 945 00:47:34,484 --> 00:47:36,720 It's almost like being in "Alice in Wonderland," right? 946 00:47:36,753 --> 00:47:39,690 Where everything is possible. 947 00:47:43,359 --> 00:47:45,128 ♪ ♪ 948 00:47:45,161 --> 00:47:46,863 NARRATOR: It was first seen 949 00:47:46,896 --> 00:47:49,766 as an unwelcome but unavoidable consequence 950 00:47:49,799 --> 00:47:52,269 of quantum mechanics. 951 00:47:52,302 --> 00:47:56,539 Now, after nearly a century of disputes and discoveries, 952 00:47:56,572 --> 00:47:58,909 "spooky action at a distance" 953 00:47:58,942 --> 00:48:03,246 is finally at the heart of modern physics. 954 00:48:03,279 --> 00:48:06,483 At the Institute for Advanced Study, 955 00:48:06,516 --> 00:48:08,685 where the concept of entanglement 956 00:48:08,718 --> 00:48:10,854 was first described, 957 00:48:10,887 --> 00:48:13,590 researchers are now using it 958 00:48:13,623 --> 00:48:17,527 in their search for a single unified theory of the universe-- 959 00:48:17,560 --> 00:48:21,698 the holy grail of physics. 960 00:48:23,266 --> 00:48:27,170 Einstein's theories of special and general relativity 961 00:48:27,203 --> 00:48:30,640 perfectly describe space, time, and gravity 962 00:48:30,673 --> 00:48:33,410 at the largest scales of the universe, 963 00:48:33,443 --> 00:48:37,414 while quantum mechanics perfectly describes 964 00:48:37,447 --> 00:48:38,782 the tiniest scales. 965 00:48:38,815 --> 00:48:44,788 Yet these two theories have never been brought together. 966 00:48:44,821 --> 00:48:48,325 So far, we have not yet had a single complete theory 967 00:48:48,358 --> 00:48:50,427 that is both quantum mechanical 968 00:48:50,460 --> 00:48:51,895 and reproduces the prediction 969 00:48:51,928 --> 00:48:56,066 of Einstein's wonderful theory of general relativity. 970 00:48:56,099 --> 00:48:59,202 Maybe the secret is entanglement. 971 00:49:01,004 --> 00:49:03,740 NARRATOR: What if space itself is actually created 972 00:49:03,773 --> 00:49:07,177 by the tiny quantum world? 973 00:49:07,210 --> 00:49:10,880 Just like temperature, warm and cold, 974 00:49:10,913 --> 00:49:15,552 consists simply of the movement of atoms inside an object, 975 00:49:15,585 --> 00:49:18,455 perhaps space as we know it 976 00:49:18,488 --> 00:49:23,526 emerges from networks of entangled quantum particles. 977 00:49:23,559 --> 00:49:27,497 It's a mind-blowing idea. 978 00:49:27,530 --> 00:49:29,699 DIJKGRAAF: What we are learning these days 979 00:49:29,732 --> 00:49:33,870 is that we might have to give up that what Einstein holds sacred, 980 00:49:33,903 --> 00:49:35,271 namely, space and time. 981 00:49:35,304 --> 00:49:37,407 So, he was always thinking, 982 00:49:37,440 --> 00:49:38,808 "Well, we have little pieces of space and time, 983 00:49:38,841 --> 00:49:42,045 and out of this, we build the whole universe." 984 00:49:42,078 --> 00:49:48,218 NARRATOR: In a radical theory-- known as the holographic universe-- 985 00:49:48,251 --> 00:49:52,155 space and time are created by entangled quantum particles 986 00:49:52,188 --> 00:49:56,259 on a sphere that's infinitely far away. 987 00:49:56,292 --> 00:49:58,995 What's happening in space 988 00:49:59,028 --> 00:50:02,365 in some sense all described 989 00:50:02,398 --> 00:50:05,668 in terms of a screen outside here. 990 00:50:05,701 --> 00:50:07,637 The ultimate description of reality 991 00:50:07,670 --> 00:50:09,806 resides on this screen. 992 00:50:09,839 --> 00:50:13,009 Think of it as kind of quantum bits living on that screen. 993 00:50:13,042 --> 00:50:16,079 And this, like a movie projector, 994 00:50:16,112 --> 00:50:19,816 creates a illusion of the three-dimensional reality 995 00:50:19,849 --> 00:50:22,219 that I'm now experiencing. 996 00:50:24,387 --> 00:50:27,757 NARRATOR: It may be impossible to intuitively understand 997 00:50:27,790 --> 00:50:30,894 this wild mathematical idea, 998 00:50:30,927 --> 00:50:32,529 but it suggests 999 00:50:32,562 --> 00:50:34,531 that entanglement could be 1000 00:50:34,564 --> 00:50:39,969 what forms the true fabric of the universe. 1001 00:50:40,002 --> 00:50:43,406 The most puzzling element of entanglement, 1002 00:50:43,439 --> 00:50:47,744 that, you know, somehow two points in space can communicate, 1003 00:50:47,777 --> 00:50:49,379 becomes less of a problem, 1004 00:50:49,412 --> 00:50:51,214 because space itself has disappeared. 1005 00:50:51,247 --> 00:50:54,918 In the end, we just have this quantum mechanical world. 1006 00:50:54,951 --> 00:50:57,654 There is no space anymore. 1007 00:50:57,687 --> 00:51:01,591 And so in some sense, the paradoxes of entanglement... 1008 00:51:01,624 --> 00:51:05,261 The EPR paradox disappears into thin air. 1009 00:51:05,294 --> 00:51:09,599 ♪ ♪ 1010 00:51:09,632 --> 00:51:12,435 CARROLL: Truly understanding quantum mechanics 1011 00:51:12,468 --> 00:51:14,571 will only happen when we put ourselves 1012 00:51:14,604 --> 00:51:16,106 on the entanglement side, 1013 00:51:16,139 --> 00:51:19,976 and we stop privileging the world that we see 1014 00:51:20,009 --> 00:51:21,644 and start thinking about the world 1015 00:51:21,677 --> 00:51:22,645 as it actually is. 1016 00:51:22,678 --> 00:51:25,448 ♪ ♪ 1017 00:51:25,481 --> 00:51:28,885 KAISER: Science has made enormous progress for centuries 1018 00:51:28,918 --> 00:51:32,422 by sort of breaking complicated systems down into parts. 1019 00:51:32,455 --> 00:51:34,591 When we come to a phenomenon like quantum entanglement, 1020 00:51:34,624 --> 00:51:36,093 that scheme breaks. 1021 00:51:37,493 --> 00:51:40,430 When it comes to the bedrock of quantum mechanics, 1022 00:51:40,463 --> 00:51:44,000 the whole is more than the sum of its parts. 1023 00:51:44,033 --> 00:51:46,035 ♪ ♪ 1024 00:51:46,068 --> 00:51:48,938 ZEILINGER: The basic motivation is 1025 00:51:48,971 --> 00:51:51,374 just to learn how nature works. 1026 00:51:51,407 --> 00:51:53,977 What's really going on? 1027 00:51:54,010 --> 00:51:55,411 Einstein said it very nicely. 1028 00:51:55,444 --> 00:51:57,780 He's not interested in this detailed question 1029 00:51:57,813 --> 00:51:59,048 or that detailed question. 1030 00:51:59,081 --> 00:52:01,684 He just wanted to know 1031 00:52:01,717 --> 00:52:06,456 what were God's thoughts when He created the world. 1032 00:52:06,489 --> 00:52:09,860 ♪ ♪ 1033 00:52:21,470 --> 00:52:26,943 ♪ ♪ 1034 00:52:34,850 --> 00:52:37,487 To order this program on DVD, 1035 00:52:37,520 --> 00:52:42,825 visit ShopPBS or call 1-800-PLAY-PBS. 1036 00:52:42,858 --> 00:52:45,495 Episodes of "NOVA" are available with Passport. 1037 00:52:45,528 --> 00:52:48,164 "NOVA" is also available on Amazon Prime Video. 1038 00:52:48,197 --> 00:52:53,637 ♪ ♪