WEBVTT 1 00:00:00.160 --> 00:00:03.640 Imagine, if you will, that you are holding a secret, just. 2 00:00:03.680 --> 00:00:05.839 A tiny, perfectly delicate secret. 3 00:00:05.960 --> 00:00:10.880 Yeah, exactly, a secret so fragile, so impossibly delicate, that 4 00:00:11.080 --> 00:00:14.160 the mere act of looking at it, it destroys it. 5 00:00:14.320 --> 00:00:16.399 The moment you try to read it, or measure it, 6 00:00:16.559 --> 00:00:19.519 or force it into the light, it just vanishes. 7 00:00:19.719 --> 00:00:22.600 It leaves behind nothing that a shadow. And now I 8 00:00:22.640 --> 00:00:24.839 just want you to ask yourself, how do you send 9 00:00:24.839 --> 00:00:26.640 a secret like that across the world? 10 00:00:26.839 --> 00:00:27.800 Is a beautiful question. 11 00:00:28.000 --> 00:00:30.760 It really is. Welcome to our quiet time together here 12 00:00:30.760 --> 00:00:34.719 on the deep dive. Come on in and just let 13 00:00:34.759 --> 00:00:38.520 out a long, slow breath, just let it go. If 14 00:00:38.560 --> 00:00:40.640 you are listening to this right now, the day is 15 00:00:40.679 --> 00:00:43.679 finally done. The sun has slipped away, and it's taken 16 00:00:43.719 --> 00:00:46.439 with it all those endless demands, you know, all. 17 00:00:46.280 --> 00:00:48.640 The bright, harsh glare of the afternoon. 18 00:00:48.280 --> 00:00:50.840 Right the sharp edges of the waking world. It is 19 00:00:50.920 --> 00:00:54.560 just us now, stepping entirely away from the noise. I 20 00:00:54.600 --> 00:00:56.200 want you to picture where we are right. 21 00:00:56.079 --> 00:00:58.000 Now, Just kind of build the space around you. 22 00:00:58.439 --> 00:01:02.359 Yeah, maybe we are sitting on a flat tarpaper rooftop 23 00:01:02.479 --> 00:01:04.599 in a sleeping city. It's two in the morning, the 24 00:01:04.640 --> 00:01:07.480 air is cool, and it's carrying just this tiny hint 25 00:01:07.519 --> 00:01:12.560 of night blooming jasmine and maybe the distant, muffled hum 26 00:01:12.640 --> 00:01:13.599 of empty streets. 27 00:01:14.000 --> 00:01:16.040 Or perhaps we're just resting right there with you in 28 00:01:16.040 --> 00:01:19.159 a comfortable, heavy bed, just looking up through a skylight 29 00:01:19.200 --> 00:01:21.560 at this vast, endless canopy of stars. 30 00:01:22.239 --> 00:01:24.560 The heavy machinery of the world has been switched off 31 00:01:24.560 --> 00:01:27.439 for the night, and in this slowing down you are 32 00:01:27.439 --> 00:01:31.079 invited to completely let go, just release it all. Let 33 00:01:31.120 --> 00:01:32.879 go of the racing thoughts, let go of the to 34 00:01:33.000 --> 00:01:36.000 do lists. They really do not belong here here under 35 00:01:36.040 --> 00:01:39.280 the quiet stars. There is absolutely nothing you need to accomplish. 36 00:01:39.359 --> 00:01:41.560 That is exactly right. I mean, just let the weight 37 00:01:41.599 --> 00:01:44.760 of your own body sink deeply into whatever is supporting 38 00:01:44.840 --> 00:01:45.680 you right now. 39 00:01:46.000 --> 00:01:47.680 Just feel that gravity, yeah, feel. 40 00:01:47.519 --> 00:01:50.120 The gravity holding you gently safely down to the Earth. 41 00:01:50.480 --> 00:01:53.239 There's little nowhere else you need to be, nowhere else, 42 00:01:53.640 --> 00:01:57.959 because in this beautiful stillness, the universe actually speaks in 43 00:01:58.000 --> 00:02:01.719 an entirely different voice. Doesn't shout over the traffic. You 44 00:02:01.760 --> 00:02:05.879 know it whispers, And tonight we are going to listen 45 00:02:05.920 --> 00:02:07.079 to one of those whispers. 46 00:02:07.079 --> 00:02:09.800 We really are tonight. We have a little journey planned. 47 00:02:10.319 --> 00:02:13.879 We are unwinding with a stack of research paper, specifically 48 00:02:14.240 --> 00:02:18.439 some truly groundbreaking work from scientists at Northwestern University, along 49 00:02:18.479 --> 00:02:22.520 with some of our own late night notes on quantum mechanics. 50 00:02:22.639 --> 00:02:24.960 But please do not let those words intimidate you. 51 00:02:25.080 --> 00:02:27.520 Oh, absolutely not. This is not a mission of effort 52 00:02:27.680 --> 00:02:30.960 or like striving to understand some complex math. It is 53 00:02:31.000 --> 00:02:33.280 simply a bedtime. 54 00:02:32.879 --> 00:02:34.360 Story, a very gentle one. 55 00:02:34.439 --> 00:02:36.840 We are going to explore one of the most beautiful 56 00:02:36.879 --> 00:02:39.800 mysteries hidden in the very fabric of reality. We're going 57 00:02:39.879 --> 00:02:42.240 to talk about quantum teleportation. 58 00:02:41.800 --> 00:02:45.080 Which sounds so intense, but it's really not right. 59 00:02:45.120 --> 00:02:46.800 I want to be clear right from the start. We 60 00:02:46.879 --> 00:02:51.400 are not talking about the loud, flashing, violent teleportation of science. 61 00:02:51.080 --> 00:02:52.599 Fiction movie no beaming people up. 62 00:02:52.800 --> 00:02:55.599 No, definitely not. We are going to explore how the 63 00:02:55.680 --> 00:02:59.560 universe allows us to transfer the essence, the precise, unique 64 00:02:59.639 --> 00:03:03.639 identity of a tiny particle across the dark, vast distances 65 00:03:03.639 --> 00:03:07.000 of space, without ever moving the physical particle itself. 66 00:03:07.240 --> 00:03:09.159 It is the perfect story for a night like this. 67 00:03:09.759 --> 00:03:12.159 I mean, people so often think of the quantum world, 68 00:03:12.439 --> 00:03:17.199 that absolute, smallest foundational layer of reality, as something cold 69 00:03:17.759 --> 00:03:19.080 or purely mechanical. 70 00:03:19.159 --> 00:03:23.520 They picture rigid mathematics, sterile white laboratories, that kind of thing. 71 00:03:23.439 --> 00:03:26.879 Exactly impenetrable jargon. But the truth is, when you peel 72 00:03:26.919 --> 00:03:28.759 back the layers and get down to the very bottom 73 00:03:28.759 --> 00:03:31.599 of things, the universe is incredibly poetic. 74 00:03:31.840 --> 00:03:32.520 It really is. 75 00:03:32.840 --> 00:03:35.639 The rules that govern these tiny building blocks of life 76 00:03:35.879 --> 00:03:38.400 are beautiful. They're almost shy in their nature. 77 00:03:38.520 --> 00:03:40.000 Shi is such a good word for it. 78 00:03:39.840 --> 00:03:42.800 It fits so well. Tonight, we will follow an invisible 79 00:03:42.840 --> 00:03:45.319 link that connects two distant points. We'll listen for a 80 00:03:45.360 --> 00:03:48.400 fragile whisper hidden beneath the roaring streets of a city 81 00:03:48.680 --> 00:03:49.960 in the year twenty twenty. 82 00:03:49.800 --> 00:03:52.680 Four, underneath all the concrete right, and. 83 00:03:52.599 --> 00:03:56.360 We will discover a beautiful, unbending rule of nature that 84 00:03:56.560 --> 00:04:01.360 proves mathematically and physically that some things are so precious 85 00:04:01.360 --> 00:04:03.039 they can only ever be lived once. 86 00:04:03.280 --> 00:04:05.599 I love that. I want to start by just gently 87 00:04:05.680 --> 00:04:08.840 unpacking that word, you know, teleportation, because I have to admit, 88 00:04:08.919 --> 00:04:11.439 when I first started looking at these papers, my mind 89 00:04:11.479 --> 00:04:13.199 immediately went straight to science fiction. 90 00:04:13.319 --> 00:04:15.520 Oh of course, everyone does you know the. 91 00:04:15.479 --> 00:04:18.720 Scene a person steps into a glass tube, a heavy 92 00:04:18.759 --> 00:04:22.480 machine hums to life, some bright laser beams down, and 93 00:04:22.519 --> 00:04:26.560 their physical body is basically zapped across space to materialize 94 00:04:26.560 --> 00:04:27.319 on a space shift. 95 00:04:27.360 --> 00:04:28.639 This is very aggressive image. 96 00:04:28.720 --> 00:04:31.000 It always felt a bit harsh to me, a bit violent, 97 00:04:31.079 --> 00:04:34.399 tearing matter apart and rebuilding it. But from what we 98 00:04:34.439 --> 00:04:37.519 are looking at in these Northwestern papers, that is not 99 00:04:37.560 --> 00:04:39.560 what the universe is doing at all, is it. We 100 00:04:39.639 --> 00:04:42.560 are not beaming a physical body anywhere. We are not 101 00:04:42.759 --> 00:04:43.439 moving matter. 102 00:04:43.639 --> 00:04:46.160 No, we are absolutely not, And you are so right 103 00:04:46.199 --> 00:04:48.920 to just let go of that loud science fiction image. 104 00:04:49.120 --> 00:04:52.199 The reality is far gentler, and frankly, it's far more mysterious. 105 00:04:52.319 --> 00:04:52.759 Gentler. 106 00:04:52.879 --> 00:04:57.040 How well, in quantum teleportation, we are never moving a 107 00:04:57.040 --> 00:04:59.480 piece of matter from point A to point B. The 108 00:04:59.560 --> 00:05:03.680 physical stuff, the particle itself, the tiny speck of matter, 109 00:05:03.959 --> 00:05:06.560 It stays exactly where it is. It never travels, It 110 00:05:06.639 --> 00:05:10.439 just sits there. Right What we are moving is its essence. 111 00:05:10.720 --> 00:05:13.759 You could think of it as the specific mood or 112 00:05:13.800 --> 00:05:15.079 the soul of the particle. 113 00:05:15.279 --> 00:05:15.759 The soul. 114 00:05:16.040 --> 00:05:18.360 Yeah. In the language of physics, we call this a 115 00:05:18.439 --> 00:05:24.399 quantum state. It is the exact, precise, unimaginably complex way 116 00:05:24.439 --> 00:05:26.959 the particle exists in a single fleeting moment. 117 00:05:27.199 --> 00:05:30.160 So we are moving the state, not the thing itself. 118 00:05:29.879 --> 00:05:33.439 Exactly teleportation is about taking that delicate state of being, 119 00:05:33.759 --> 00:05:37.439 dissolving it in one place, and letting it bloom perfectly 120 00:05:37.519 --> 00:05:41.000 and miraculously inside an entirely different particle far away. 121 00:05:41.240 --> 00:05:44.600 So the body stays behind, but the essence travels. I'm 122 00:05:44.600 --> 00:05:46.399 just trying to wrap my mind around what that actually 123 00:05:46.399 --> 00:05:48.199 feels like. Let me try this. Is it sort of 124 00:05:48.240 --> 00:05:49.240 like a beautiful melody? 125 00:05:49.279 --> 00:05:50.560 Okay, yeah, let's explore that. 126 00:05:50.720 --> 00:05:54.279 Imagine you have a guitar, just an old, worn acoustic guitar. 127 00:05:54.680 --> 00:05:56.240 You were sitting in your living room in the dark, 128 00:05:56.319 --> 00:05:59.560 and you pluck the strings to create this incredibly complex. 129 00:05:59.120 --> 00:06:02.079 Moving cord, just letting the sound ring out right. 130 00:06:02.279 --> 00:06:05.600 The wood vibrates, the sound fills the room. That chord 131 00:06:05.680 --> 00:06:08.480 has a very specific feeling. Now, if you want your 132 00:06:08.519 --> 00:06:11.680 friend across the world to experience that exact same chord, 133 00:06:12.160 --> 00:06:14.480 you don't need to pack up your physical guitar, put 134 00:06:14.519 --> 00:06:16.600 it in a wooden box and mail it to them. 135 00:06:16.879 --> 00:06:19.800 No, the instrument doesn't matter as much as the music exactly. 136 00:06:19.839 --> 00:06:21.959 The guitar itself does not need to move. You just 137 00:06:21.959 --> 00:06:24.839 need to send the notes, the vibration, the actual feeling 138 00:06:25.000 --> 00:06:28.279 of the music, and when that feeling arrives, they can 139 00:06:28.319 --> 00:06:29.439 play it on their own guitar. 140 00:06:30.120 --> 00:06:33.519 The music simply leaves your room and begins playing in theirs. 141 00:06:33.720 --> 00:06:35.680 Right, is that kind of what we're talking about. 142 00:06:35.800 --> 00:06:36.279 I love that. 143 00:06:36.399 --> 00:06:36.560 Yeah. 144 00:06:36.639 --> 00:06:39.240 Yes, that is a beautiful way to hold the concept 145 00:06:39.240 --> 00:06:42.680 in your mind without getting lost in the math that 146 00:06:42.879 --> 00:06:46.519 complex cored you just described. That's what physicists call a superposition. 147 00:06:46.720 --> 00:06:48.720 Superposition okay, yeah. 148 00:06:48.319 --> 00:06:51.560 Because in the everyday world things are simple. A light 149 00:06:51.600 --> 00:06:54.319 switch is either on or off. A coin on the 150 00:06:54.319 --> 00:06:57.399 table is either heads or tails, right, very binary. But 151 00:06:57.560 --> 00:07:00.319 in the quantum world, before we look closely at it, 152 00:07:00.759 --> 00:07:04.079 a particle can be spinning up and spinning down at 153 00:07:04.120 --> 00:07:07.279 the exact same time. It's like a coin that is 154 00:07:07.399 --> 00:07:10.399 endlessly spinning in the air, just a blur of possibilities. 155 00:07:10.439 --> 00:07:11.959 So it's not just a single note. 156 00:07:12.160 --> 00:07:14.199 No, it is not just one note. It is a 157 00:07:14.279 --> 00:07:18.279 rich tapestry of potential ringing out all at once. That 158 00:07:18.480 --> 00:07:19.680 is the quantum state. 159 00:07:19.639 --> 00:07:21.720 The spinning coin, the complex chord. 160 00:07:21.959 --> 00:07:26.720 Right. So to teleport, it means the music that the 161 00:07:26.759 --> 00:07:30.839 blur of possibilities simply fades into silence in one room 162 00:07:31.079 --> 00:07:33.920 and then across the city or across the ocean. It 163 00:07:34.000 --> 00:07:37.120 seamlessly begins playing in another room, and the original guitar, 164 00:07:37.199 --> 00:07:40.399 the original guitar, is left totally silent. The physical instrument 165 00:07:40.639 --> 00:07:42.720 never moved, only the music. 166 00:07:42.560 --> 00:07:44.759 Moved, just breathing in that idea for a moment. The 167 00:07:44.839 --> 00:07:47.360 universe allows the music to travel without the instrument. It 168 00:07:47.360 --> 00:07:48.319 feels so light, you. 169 00:07:48.279 --> 00:07:49.399 Know, so unburdened. 170 00:07:49.480 --> 00:07:53.120 Yeah, completely unburdened by heavy physical things. But I do 171 00:07:53.160 --> 00:07:54.839 need to pause you there for a second, because if 172 00:07:54.879 --> 00:07:56.480 the music is going to travel like that, if this 173 00:07:56.639 --> 00:07:59.800 incredibly complex essence is going to cross the dark space 174 00:08:00.000 --> 00:08:02.120 between those two rooms, there has to be. 175 00:08:02.040 --> 00:08:04.199 A connection, right, you would think so, Yes. 176 00:08:04.160 --> 00:08:07.000 There has to be some kind of bridge that allows 177 00:08:07.120 --> 00:08:10.600 the feeling to pass from my room to yours. Otherwise 178 00:08:10.639 --> 00:08:13.600 they are just isolated islands. How does the music nowhere 179 00:08:13.680 --> 00:08:13.959 to go? 180 00:08:14.439 --> 00:08:17.560 You have hit on the exact heart of the mystery. Yes, 181 00:08:17.879 --> 00:08:20.879 there must be a bridge, and that bridge is perhaps 182 00:08:20.959 --> 00:08:24.040 the most magical, mind bending part of this entire story. 183 00:08:24.120 --> 00:08:25.639 Okay, I'm ready to. 184 00:08:25.519 --> 00:08:27.720 Make this transfer of the essence work. We have to 185 00:08:27.759 --> 00:08:32.480 rely on a phenomenon called quantum entanglement. Entanglement, but let's 186 00:08:32.519 --> 00:08:35.159 just set aside this sterile laboratory definition for a moment. 187 00:08:35.639 --> 00:08:39.679 Let's picture it as an invisible, unbreakable. 188 00:08:39.039 --> 00:08:41.080 Thread, an invisible thread. 189 00:08:41.200 --> 00:08:43.679 When two particles interact in just the right way, say 190 00:08:44.240 --> 00:08:46.399 they are born from the exact same flash of light, 191 00:08:46.559 --> 00:08:48.679 they become linked by this thread. They become part of 192 00:08:48.720 --> 00:08:50.080 the exact same story. 193 00:08:50.200 --> 00:08:50.759 Oh wow. 194 00:08:51.159 --> 00:08:55.039 From that moment on, their destinies are completely shared. What 195 00:08:55.159 --> 00:08:59.039 happens to one in a very real, deep, instantaneous way 196 00:08:59.279 --> 00:09:00.240 is felt by the other. 197 00:09:00.440 --> 00:09:03.440 So once these two particles meet and share this deep connection, 198 00:09:03.639 --> 00:09:05.480 they are entangled. I could take one of them and 199 00:09:05.559 --> 00:09:08.360 just like walk it across the rooftop here you could, 200 00:09:08.480 --> 00:09:11.480 or I could take it across the city, or theoretically, 201 00:09:11.559 --> 00:09:13.600 I could put it on a silent rocket and send 202 00:09:13.639 --> 00:09:16.519 it to the very edge of the Solar System, leaving 203 00:09:16.559 --> 00:09:20.000 it to rest on the cold, quiet surface of Pluto 204 00:09:20.360 --> 00:09:22.039 all the way to Pluto, and they would still be 205 00:09:22.080 --> 00:09:23.720 connected exactly. 206 00:09:23.559 --> 00:09:25.919 Space in the way you and I normally think about 207 00:09:25.960 --> 00:09:29.440 it as a vast empty distance that takes time to 208 00:09:29.480 --> 00:09:32.720 cross it. It just becomes an absolute illusion for these 209 00:09:32.720 --> 00:09:36.759 two particles, an illusion. Yeah, the physical distance between them 210 00:09:37.000 --> 00:09:40.159 no longer matters. Whether they are resting inches apart on 211 00:09:40.159 --> 00:09:43.960 a velvet table, or separated by billions of miles of 212 00:09:44.360 --> 00:09:48.080 empty starlit void. They are holding opposite ends of that 213 00:09:48.200 --> 00:09:49.320 exact same connection. 214 00:09:49.639 --> 00:09:52.080 That is just incredible to think about. 215 00:09:52.200 --> 00:09:54.159 If you gently pluck one end of the link here 216 00:09:54.200 --> 00:09:56.480 on Earth, a shiver instantly travels down the line, and 217 00:09:56.519 --> 00:10:00.519 the particle on Pluto feels it instantly, faster than light. 218 00:10:00.480 --> 00:10:03.720 Faster than a light. It makes me think of twin siblings. 219 00:10:03.720 --> 00:10:05.000 You shar those stories sometimes, right? 220 00:10:05.080 --> 00:10:05.200 Oh? 221 00:10:05.279 --> 00:10:09.240 Yeah, the intuition twins share exactly twins who are separated 222 00:10:09.240 --> 00:10:12.440 by oceans, living completely different lives. One of them is 223 00:10:12.480 --> 00:10:15.799 sitting at a small, quiet cafe in Paris, sipping coffee, 224 00:10:15.879 --> 00:10:18.759 and suddenly they just know with absolute certainty that their 225 00:10:18.799 --> 00:10:20.039 twin in New York is sad. 226 00:10:20.240 --> 00:10:21.759 A sudden heaviness in the chest. 227 00:10:21.960 --> 00:10:26.000 Yeah. Or think of two distant lovers separated by a 228 00:10:26.039 --> 00:10:28.320 long journey, who agree to look up at the moon 229 00:10:28.440 --> 00:10:32.480 at the exact same hour. They are standing on different soils, 230 00:10:32.559 --> 00:10:35.039 breathing different air, but their gaze meets on that same 231 00:10:35.080 --> 00:10:38.000 pale light, and in that moment, the distance between them 232 00:10:38.039 --> 00:10:38.679 just vanishes. 233 00:10:39.080 --> 00:10:40.720 The miles don't exist anymore, right. 234 00:10:40.759 --> 00:10:42.799 They are connected by a shared state of being that 235 00:10:42.879 --> 00:10:46.720 completely ignores the physical miles. But this brings up a 236 00:10:46.720 --> 00:10:49.200 paradox for me. What's that If this threat is so 237 00:10:49.240 --> 00:10:53.759 perfectly connected, if it ignores space entirely and travels instantly, 238 00:10:54.440 --> 00:10:57.480 is it strong or is it delicate? Because the everyday 239 00:10:57.480 --> 00:10:59.960 world we live in is not a gentle place. It's loud, 240 00:11:00.159 --> 00:11:00.679 it's messy. 241 00:11:00.879 --> 00:11:03.919 That is a very perceptive question, and honestly, it is 242 00:11:03.960 --> 00:11:06.600 the fundamental hurdle that physicists have been trying to overcome 243 00:11:06.639 --> 00:11:11.440 for decades. The connection is incredibly heartbreakingly. 244 00:11:10.720 --> 00:11:12.480 Delicate, heartbreakingly delicate. 245 00:11:12.840 --> 00:11:16.200 Yes, we use words like thread or link, but it's 246 00:11:16.240 --> 00:11:18.360 not made of steel or stone. It's made of the 247 00:11:18.440 --> 00:11:22.960 quietest whispers of nature. In physics, we struggle with something 248 00:11:23.000 --> 00:11:28.159 called decoherence. Decoherence, you see the quantum state, that spinning coin, 249 00:11:28.240 --> 00:11:31.399 that beautiful cord of music. It can only exist if 250 00:11:31.399 --> 00:11:34.559 it is completely isolated. The very moment it interacts with 251 00:11:34.639 --> 00:11:37.159 the messy, everyday world, it collapses. 252 00:11:37.279 --> 00:11:39.120 So any interference at all. 253 00:11:38.960 --> 00:11:41.759 Anything heat in the room, a tiny fluctuation in a 254 00:11:41.799 --> 00:11:44.759 magnetic field, a stray particle of light just bumping into it, 255 00:11:45.120 --> 00:11:47.120 even simple act of a scientist trying to look too 256 00:11:47.120 --> 00:11:50.840 closely at it. All these things act like a rough, violent. 257 00:11:50.519 --> 00:11:52.559 Wind, and the wind snaps the thread. 258 00:11:52.440 --> 00:11:55.679 Exactly, the wind snaps the invisible thread. The music stops, 259 00:11:55.879 --> 00:11:57.879 the spinning coin hits a grain of sand and falls 260 00:11:57.879 --> 00:12:00.759 flat onto the table, becoming just a regular boring heads 261 00:12:00.840 --> 00:12:01.240 or tails. 262 00:12:01.360 --> 00:12:04.080 It snaps the thread, the connection just dissolves. 263 00:12:04.279 --> 00:12:07.720 Yes, the moment, the outside world intruthes, the magic fades. 264 00:12:08.240 --> 00:12:11.639 That is why keeping this entanglement alive is a quiet, beautiful, 265 00:12:12.000 --> 00:12:14.639 agonizing challenge for anyone trying to study it. I can 266 00:12:14.679 --> 00:12:17.440 imagine you have to cradle these particles. You have to 267 00:12:17.480 --> 00:12:20.799 shield them in freezing vacuums, protecting them from the loud 268 00:12:20.840 --> 00:12:24.000 noise of the day. Which is why this quiet night, 269 00:12:24.559 --> 00:12:28.039 where everything is still and cool, is just a perfect 270 00:12:28.080 --> 00:12:29.080 backdrop for this. 271 00:12:29.159 --> 00:12:30.759 Concept, because it means the quiet. 272 00:12:30.799 --> 00:12:35.320 It demands the quiet, because this fragile, invisible bridge is 273 00:12:35.399 --> 00:12:38.840 the absolute only way the essence of our particle can travel. 274 00:12:38.960 --> 00:12:41.559 So we have our delicate music, our essence, and we 275 00:12:41.639 --> 00:12:46.360 have this incredibly fragile invisible bridge spanning the distance. Let's 276 00:12:46.360 --> 00:12:48.200 give this a story, let's ground. 277 00:12:47.879 --> 00:12:50.240 It a little bit. I think that's a great idea. 278 00:12:49.799 --> 00:12:51.879 In the world of physics, Whenever scientists talk about this, 279 00:12:51.960 --> 00:12:54.240 they always use the same two names, Alice and Bob. 280 00:12:54.679 --> 00:12:57.519 But tonight, let's not picture them as scientists and white 281 00:12:57.519 --> 00:13:02.159 coats standing under harsh fluorescent light. It's surrounded by humming computers. 282 00:13:02.240 --> 00:13:03.440 Yeah, let's bring him outside. 283 00:13:03.559 --> 00:13:06.919 Yeah, let's picture Alice and Bob as two dear friends. 284 00:13:07.159 --> 00:13:08.960 It's late at night, just like it is for us. 285 00:13:09.519 --> 00:13:12.559 Alice is standing on her rooftop in one city, looking 286 00:13:12.559 --> 00:13:15.480 out over the sleeping foces, her breath just catching in 287 00:13:15.519 --> 00:13:16.240 the cool air. 288 00:13:16.399 --> 00:13:17.080 I can picture that. 289 00:13:17.320 --> 00:13:19.879 And Bob is standing on a balcony in a completely 290 00:13:19.879 --> 00:13:22.799 different city, miles and miles away, looking up at the 291 00:13:22.879 --> 00:13:27.000 exact same stars, and stretching between them across the dark, 292 00:13:27.320 --> 00:13:31.679 quiet earth is our entangled link. Alice is holding one end, 293 00:13:31.879 --> 00:13:32.919 Bob is holding the other. 294 00:13:33.360 --> 00:13:36.080 I can see them perfectly. They're wrapped in warm coats 295 00:13:36.159 --> 00:13:39.799 against the night air, holding this profound, silent connection in 296 00:13:39.840 --> 00:13:40.279 their hands. 297 00:13:40.320 --> 00:13:42.879 It is feeling that subtle link right now. 298 00:13:42.919 --> 00:13:45.240 Alice has something she wants to share with Bob. In 299 00:13:45.279 --> 00:13:48.480 her other hand, she holds a third part. This is 300 00:13:48.519 --> 00:13:52.039 the message, the secret. It is a tiny, fragile secret. 301 00:13:52.360 --> 00:13:55.240 It is that beautiful complex cord of music we talked 302 00:13:55.240 --> 00:13:59.240 about earlier, a totally unique superposition. She wants Bob to 303 00:13:59.279 --> 00:14:01.679 have this secret, to feel this exact core. 304 00:14:01.799 --> 00:14:03.240 But she can't just toss it to him. 305 00:14:03.360 --> 00:14:05.679 No, she knows she cannot just throw it across the miles. 306 00:14:06.000 --> 00:14:08.120 The secret is way too delicate. It would be destroyed 307 00:14:08.120 --> 00:14:10.440 by the wind and the noise. She has to use 308 00:14:10.440 --> 00:14:11.360 the invisible bridge. 309 00:14:11.360 --> 00:14:13.399 Wait, I need to pause you there, because I am 310 00:14:13.440 --> 00:14:16.399 picturing Alice holding the secret in one hand and her 311 00:14:16.519 --> 00:14:19.279 end of the entangled bridge in the other. How does 312 00:14:19.320 --> 00:14:21.519 she actually give the secret to the bridge? 313 00:14:21.720 --> 00:14:23.240 That is the tricky part. 314 00:14:23.200 --> 00:14:25.519 Because you just said that if anything interacts with a 315 00:14:25.600 --> 00:14:29.440 quantum state, it collapses. If she touches it, doesn't she 316 00:14:29.519 --> 00:14:34.320 destroy it. Let's take this very very slowly, a glacial pace. 317 00:14:35.240 --> 00:14:36.080 How does she do it? 318 00:14:36.639 --> 00:14:39.320 You're absolutely right to spot that danger. If she just 319 00:14:39.440 --> 00:14:42.480 looks at the secret to try and read it, it's gone. 320 00:14:43.000 --> 00:14:47.159 So she does something deeply counterintuitive. She performs what scientists 321 00:14:47.200 --> 00:14:48.840 call a Bell state measurement. 322 00:14:48.960 --> 00:14:50.559 A Bell state measurement. 323 00:14:50.320 --> 00:14:53.919 Right, But for us sitting here in the quiet, let's 324 00:14:53.919 --> 00:14:57.279 just picture it as a soft, gentle squeeze. She brings 325 00:14:57.279 --> 00:14:59.919 a delicate secret and her end of the invisible brid 326 00:15:00.360 --> 00:15:01.200 close together in. 327 00:15:01.159 --> 00:15:02.679 Her hands, okay, bringing them together. 328 00:15:02.879 --> 00:15:05.000 Instead of trying to look at the secret itself, she 329 00:15:05.159 --> 00:15:08.399 forces the secret and the bridge to interact with each other. 330 00:15:08.799 --> 00:15:10.600 She measures how they relate to one another. 331 00:15:10.720 --> 00:15:11.399 Oh, I see. 332 00:15:11.559 --> 00:15:13.519 But in the quantum world, the act of measuring them 333 00:15:13.519 --> 00:15:17.240 together locks them together. The very moment she squeezes her hands, 334 00:15:17.279 --> 00:15:20.159 the original secret is overwritten. It dissolves from her hands. 335 00:15:20.240 --> 00:15:21.159 It just fades away. 336 00:15:21.360 --> 00:15:25.120 The beautiful music fades into silence on her rooftop. The specific, 337 00:15:25.320 --> 00:15:29.519 unique soul of that particle entirely vanishes from Alice's side. 338 00:15:29.720 --> 00:15:32.240 She let it go. It dissolved just by forcing them 339 00:15:32.240 --> 00:15:34.720 to interact. She destroyed the very thing she was trying 340 00:15:34.759 --> 00:15:37.679 to save. But it didn't just vanish into nothing, did it. 341 00:15:37.679 --> 00:15:39.039 It must have left something behind. 342 00:15:39.399 --> 00:15:43.000 It did. When the secret dissolved in that gentle squeeze, 343 00:15:43.440 --> 00:15:47.600 it left behind a faint ripple, a tiny, simple sequence 344 00:15:47.600 --> 00:15:50.279 of two classical numbers. Numbers. Think of it like a 345 00:15:50.320 --> 00:15:54.240 brief quiet sigh that translates into a simple code. A 346 00:15:54.399 --> 00:15:58.399 zero and a one or two ones, just two tiny 347 00:15:58.840 --> 00:16:00.279 ordinary bits of information. 348 00:16:00.399 --> 00:16:00.799 Okay. 349 00:16:01.200 --> 00:16:03.759 But and this is where the universe reveals its magic 350 00:16:04.200 --> 00:16:07.799 the absolute instant, Alice squeezed her hand. Because of that 351 00:16:07.879 --> 00:16:10.679 invisible bridge, a shiver traveled all the way across the 352 00:16:10.720 --> 00:16:15.000 miles to Bob instantly. Instantly, Bob's end of the thread vibrated, 353 00:16:15.240 --> 00:16:18.559 the essence of Alice's secret. The music left Alice's rooftop 354 00:16:18.600 --> 00:16:21.840 and is now hovering right there around Bob's hands, waiting 355 00:16:21.840 --> 00:16:22.360 in the dark. 356 00:16:22.559 --> 00:16:26.200 So the music jumped the distance, but Bob cannot hear 357 00:16:26.200 --> 00:16:29.679 it yet, can he His thread just looks slightly altered. 358 00:16:29.720 --> 00:16:32.080 He feels the vibration, but he's standing in the dark. 359 00:16:32.200 --> 00:16:33.960 He knows something happened, but he doesn't know what. 360 00:16:34.559 --> 00:16:36.960 Right, what does Alice do next? Because if the secret 361 00:16:37.000 --> 00:16:39.559 is hovering around Bob but he can't access it, it's 362 00:16:39.639 --> 00:16:41.000 completely useless. 363 00:16:41.159 --> 00:16:43.240 This is actually my favorite part of the whole protocol 364 00:16:43.480 --> 00:16:47.960 because it is wonderfully almost comically ordinary. Right, Alice has 365 00:16:48.000 --> 00:16:50.799 those two numbers left in her hand, the ripple. Right, 366 00:16:51.360 --> 00:16:55.200 Bob feels the shiver, but his particle is tumbling slightly 367 00:16:55.279 --> 00:16:58.759 out of alignment. So Alice pulls out her phone. She 368 00:16:58.840 --> 00:17:02.000 makes a regular class phone call to her friend Bob, 369 00:17:02.200 --> 00:17:04.559 a phone call. The phone rings in the quiet night. 370 00:17:04.880 --> 00:17:09.599 Bob answers, and Alice softly whispers those two numbers to him, 371 00:17:09.640 --> 00:17:13.039 just a simple human conversation over copper wires and cell towers. 372 00:17:13.319 --> 00:17:16.319 Wait, really a phone call. With all this instant, faster 373 00:17:16.440 --> 00:17:19.119 than light quantum magic going on, it relies on a 374 00:17:19.200 --> 00:17:19.720 phone call. 375 00:17:19.880 --> 00:17:22.039 It does in physics, we call it a Polly correction. 376 00:17:22.599 --> 00:17:25.519 Bob listens to the phone call, he hears the two numbers. 377 00:17:25.559 --> 00:17:27.240 Alice whispers. Those numbers are the. 378 00:17:27.200 --> 00:17:30.200 Key, the key to unlock the music exactly. 379 00:17:30.440 --> 00:17:32.960 They tell Bob exactly how his particle is tumbling out 380 00:17:32.960 --> 00:17:37.279 of alignment. Based on what Alice whispered, he knows exactly 381 00:17:37.279 --> 00:17:39.559 how to hold his end of the thread. He turns 382 00:17:39.599 --> 00:17:43.039 it gently, adjusting it just the way she instructed, maybe 383 00:17:43.160 --> 00:17:45.920 a tiny rotation to the left or a soft flip. 384 00:17:46.480 --> 00:17:49.559 And the moment he makes that tiny, precise adjustment based 385 00:17:49.559 --> 00:17:53.599 on her whispered numbers, the secret materializes perfectly in his hands. 386 00:17:54.279 --> 00:17:56.759 The chord of music begins to play on his balcony, 387 00:17:57.119 --> 00:17:58.839 exactly as it was on her rooftop. 388 00:17:59.160 --> 00:18:01.440 I just want to wrap with that image for a moment, 389 00:18:01.519 --> 00:18:04.440 the music blooming in Bob's hands. It's so beautiful, What 390 00:18:04.519 --> 00:18:07.400 I love so deeply about this story is the absurdity 391 00:18:07.440 --> 00:18:07.759 of it. 392 00:18:07.759 --> 00:18:09.079 It is a bit absurd, isn't it. 393 00:18:09.079 --> 00:18:13.119 It is even with a magic, instantaneous thread connecting their souls, 394 00:18:13.599 --> 00:18:15.880 Alice still has to make a normal phone call. It 395 00:18:15.960 --> 00:18:20.119 keeps all of this grand cosmic magic so beautifully grounded. 396 00:18:20.319 --> 00:18:22.200 It anchors it to our human reality. 397 00:18:22.319 --> 00:18:26.000 Yeah, the universe has given us this profound instant connection, 398 00:18:26.440 --> 00:18:28.559 but it still demands that we take the time to talk. 399 00:18:28.599 --> 00:18:30.039 It demands that we pick up the phone, that we 400 00:18:30.160 --> 00:18:33.039 listen to each other's voices, and the phone call travels at. 401 00:18:32.880 --> 00:18:34.920