WEBVTT 1 00:00:01.480 --> 00:00:05.599 Welcome to the quark Side. Quantum Physics podcast, an exploration 2 00:00:05.679 --> 00:00:10.919 of the fundamental structure of reality, where quantum laws govern matter, energy, 3 00:00:11.199 --> 00:00:16.239 and information. Here, uncertainty is a feature, not a flaw, 4 00:00:16.719 --> 00:00:19.239 and understanding begins at the smallest scales. 5 00:00:27.519 --> 00:00:29.320 I want you to try something with me. It's a 6 00:00:30.719 --> 00:00:33.039 mental exercise I do sometimes when I can't sleep. 7 00:00:33.119 --> 00:00:34.439 Oh boy, okay, I'm listening. 8 00:00:34.719 --> 00:00:37.679 Imagine you are standing in the middle of the Great 9 00:00:37.799 --> 00:00:42.320 Basin desert, just you, the silence, and the ground beneath 10 00:00:42.359 --> 00:00:45.640 your feet. It's midnight, no moon. You look up. 11 00:00:46.119 --> 00:00:48.039 I know this view. It's one of the most humbling 12 00:00:48.119 --> 00:00:48.600 views on. 13 00:00:48.560 --> 00:00:51.359 Earth, it really is. You see the Milky Way arching 14 00:00:51.399 --> 00:00:53.880 over you. You know that dense river of stars. You 15 00:00:53.920 --> 00:00:57.679 see Jupiter, maybe Mars, but mostly, if you're being honest 16 00:00:57.679 --> 00:01:02.320 about what your eyes are actually registering, you see black darkness. Yeah, 17 00:01:02.399 --> 00:01:07.719 sheer darkness, right, vast crushing darkness. And our brain has 18 00:01:07.760 --> 00:01:11.480 a very specific default setting for interpreting that darkness. We 19 00:01:11.480 --> 00:01:13.359 look at the space between the stars and we think 20 00:01:13.760 --> 00:01:14.680 that is empty. 21 00:01:14.760 --> 00:01:17.760 It's the ultimate intuitive assumption. I mean, it makes perfect sense. 22 00:01:18.040 --> 00:01:19.640 If I take a box and I pump out all 23 00:01:19.680 --> 00:01:22.200 the air, sweep of the dust block the light and 24 00:01:22.359 --> 00:01:24.480 I don't know shield it from magnetic fields. I have 25 00:01:24.480 --> 00:01:25.760 an empty box. I have nothing. 26 00:01:26.000 --> 00:01:28.359 And for most of human history that was it. That 27 00:01:28.480 --> 00:01:30.760 was the assumption. The void is just well, it's the 28 00:01:30.760 --> 00:01:34.879 absence of stuff. But today we're going to take a 29 00:01:34.959 --> 00:01:39.480 sledgehammer to that intuition, because it turns out that empty 30 00:01:39.480 --> 00:01:41.439 box doesn't exist. 31 00:01:41.120 --> 00:01:42.280 It really really doesn't. 32 00:01:42.319 --> 00:01:45.680 We're going to explore the quantum vacuum, and the headline, 33 00:01:45.719 --> 00:01:50.120 which sounds completely contradictory, is that nothing is actually something. 34 00:01:50.200 --> 00:01:53.439 In fact, empty space might be the most active, chaotic, 35 00:01:53.480 --> 00:01:55.719 and energetic thing in the entire universe. 36 00:01:55.840 --> 00:01:59.079 It's a foundation of reality. That's not an exaggeration. It's 37 00:01:59.120 --> 00:02:02.400 not just a backdrop the action. It's a seating ocean 38 00:02:02.400 --> 00:02:06.480 of activity that shapes atoms, that evaporates black holes, and 39 00:02:06.680 --> 00:02:09.080 might even be responsible for the Big Bang itself. 40 00:02:09.319 --> 00:02:11.439 So if you could actually see what's happening in those 41 00:02:11.520 --> 00:02:14.719 dark patches of the night sky, you wouldn't see emptiness 42 00:02:14.719 --> 00:02:15.039 at all. 43 00:02:15.199 --> 00:02:16.919 No, you'd see a riot. 44 00:02:16.759 --> 00:02:18.800 All right in the void. I love that image. But 45 00:02:18.840 --> 00:02:20.520 before we get to the kaas, we have to, you know, 46 00:02:20.560 --> 00:02:22.719 respect the history here, because for a long time, the 47 00:02:22.719 --> 00:02:25.639 smartest people on Earth. We're talking Newton, gal Leo. They 48 00:02:25.639 --> 00:02:26.960 were firmly on team empty. 49 00:02:27.199 --> 00:02:29.759 Oh. Absolutely, And it makes sense, doesn't it. This is 50 00:02:29.759 --> 00:02:31.960 what we call the classical view. Think about Isaac Newton. 51 00:02:32.400 --> 00:02:37.319 For him, space was a stage, a stage, a passive, 52 00:02:37.319 --> 00:02:41.159 wooden stage. The actors were the planets, the stars, you know, 53 00:02:41.199 --> 00:02:43.840 the apples falling from trees. They moved around on the stage. 54 00:02:43.840 --> 00:02:45.840 They bumped into each other, gravity pulled them this way 55 00:02:45.879 --> 00:02:49.560 and that. But the stage itself, it did nothing. It 56 00:02:49.599 --> 00:02:52.680 was just the container, an inert, passive background. 57 00:02:52.759 --> 00:02:56.280 So it was just there. If you kicked all the 58 00:02:56.280 --> 00:02:58.639 actors off the stage, if you somehow removed all the 59 00:02:58.680 --> 00:03:01.080 matter and energy from the universe, the stage would just 60 00:03:01.120 --> 00:03:03.719 sit there, existing but completely dead. 61 00:03:03.879 --> 00:03:07.520 Exactly in classical physics, and this includes Maxwell's incredible work 62 00:03:07.560 --> 00:03:13.759 on electromagnetism later on, the definition of empty was basically 63 00:03:13.800 --> 00:03:15.240 a mathematical zero. 64 00:03:15.159 --> 00:03:17.759 No particles, no particles, tell us no radiation, well us 65 00:03:17.800 --> 00:03:18.800 no radiation. 66 00:03:18.520 --> 00:03:21.479 And that equals a zero field value. That equals truly 67 00:03:21.599 --> 00:03:22.599 fundamentally empty. 68 00:03:22.800 --> 00:03:25.599 And to be fair, this view worked. It worked beautifully 69 00:03:25.599 --> 00:03:26.360 for centuries. 70 00:03:26.639 --> 00:03:30.680 It did. It predicted planetary orbits with stunning accuracy. It 71 00:03:30.759 --> 00:03:34.240 let us build bridges, design machines. There was absolutely no 72 00:03:34.360 --> 00:03:35.199 reason to doubt. 73 00:03:35.039 --> 00:03:37.360 It until the twentieth century showed up and decided to 74 00:03:37.439 --> 00:03:42.159 ruin everyone's simple, organized life or make it infinitely more fascinating, 75 00:03:42.479 --> 00:03:45.000 depending on how much you like linear algebra. I guess, 76 00:03:45.439 --> 00:03:48.520 so the quantum revolution happens. What was the specific thing, 77 00:03:48.759 --> 00:03:53.199 the smoking gun that killed the idea of the empty container? 78 00:03:53.520 --> 00:03:56.840 It wasn't one single discovery, but it all hinges on 79 00:03:56.840 --> 00:04:00.280 one fundamental rule, a pillar of the whole theory. Yeah, 80 00:04:00.319 --> 00:04:02.080 the Heisenberg uncertainty principle. 81 00:04:02.080 --> 00:04:04.080 Okay, I know this one, or I think I do. 82 00:04:04.520 --> 00:04:06.680 This is you can't know where a particle is and 83 00:04:06.759 --> 00:04:08.439 how fast it's going at the same time. 84 00:04:08.599 --> 00:04:11.719 Rule. Right, that's the version most people learn in school, 85 00:04:11.719 --> 00:04:15.319 and it's absolutely correct position and momentum. But the uncertainty 86 00:04:15.319 --> 00:04:19.120 principle is actually a much deeper, much broader statement about 87 00:04:19.160 --> 00:04:20.720 the nature of reality itself. 88 00:04:20.800 --> 00:04:23.560 So it's not just about position and speed, not at all. 89 00:04:23.920 --> 00:04:26.279 It applies to other pairs of properties too, You can 90 00:04:26.319 --> 00:04:29.240 think of them as complementary variables. And the one that 91 00:04:29.360 --> 00:04:32.920 completely breaks the concept of nothing is the relationship between 92 00:04:33.120 --> 00:04:34.000 energy and time. 93 00:04:34.600 --> 00:04:37.240 Energy and time, So you can't know the energy and 94 00:04:37.319 --> 00:04:40.879 the time simultaneously. That sounds a little more abstract. 95 00:04:40.680 --> 00:04:43.040 It is, but think of it like photography. You know, 96 00:04:43.160 --> 00:04:44.680 if you're trying to take a picture of a fast 97 00:04:44.680 --> 00:04:48.079 moving car, you need a really really fast shutter speed 98 00:04:48.240 --> 00:04:49.839 to freeze the action right. 99 00:04:50.240 --> 00:04:52.360 If the shutter is open too long, the car is 100 00:04:52.399 --> 00:04:54.879 just a blur. If it's open for a millisecond, the 101 00:04:54.959 --> 00:04:56.839 image is crisp, exactly. 102 00:04:57.680 --> 00:04:59.839 But there's a trade off, isn't there. To get that 103 00:05:00.079 --> 00:05:04.240 crisp frozen moment that is a super precise measurement of time, 104 00:05:04.879 --> 00:05:07.079 you have to let in very little light. You lose 105 00:05:07.160 --> 00:05:10.160 information about the scene, about the energy of the photons 106 00:05:10.199 --> 00:05:11.639 because your window is so short. 107 00:05:11.800 --> 00:05:12.839 Okay, I'm following. 108 00:05:13.079 --> 00:05:16.680 The uncertainty principle is like the ultimate unbreakable shutter speed 109 00:05:16.759 --> 00:05:17.639 limit for the universe. 110 00:05:17.879 --> 00:05:19.399 So how does that apply to energy. 111 00:05:19.600 --> 00:05:22.079 Well, the formula states that the uncertainty and energy we 112 00:05:22.160 --> 00:05:25.319 call it delta e multiplied by the uncertainty in time 113 00:05:25.480 --> 00:05:29.319 delta T must be greater than or equal to a 114 00:05:29.360 --> 00:05:32.199 specific tiny number half of planks. 115 00:05:31.800 --> 00:05:34.199 Constant, which is a famously tiny number. 116 00:05:34.279 --> 00:05:36.959 It is incredibly tiny, But the crucial part is that 117 00:05:37.000 --> 00:05:40.519 it is not zero, and that distinction, that tiny non 118 00:05:40.600 --> 00:05:42.800 zero value changes everything. 119 00:05:42.879 --> 00:05:44.040 Okay, so what does that tell us? 120 00:05:44.279 --> 00:05:47.160 It tells us that nature forbids you from knowing the 121 00:05:47.199 --> 00:05:50.199 exact energy state of a system if you look at 122 00:05:50.279 --> 00:05:51.800 it for a brief enough window of time. 123 00:05:52.160 --> 00:05:54.560 So if I try to take an incredibly fast snapshot 124 00:05:54.600 --> 00:05:56.720 of empty space, the image. 125 00:05:56.399 --> 00:05:59.639 Of the energy becomes blurry. It has to. The uncertainty 126 00:05:59.639 --> 00:06:02.279 in the energy explodes to compensate for the certainty in 127 00:06:02.319 --> 00:06:05.639 the time. It means that on very very short time scales, 128 00:06:05.920 --> 00:06:09.360 the energy of any specific point in space must fluctuate. 129 00:06:09.480 --> 00:06:11.920 Hang on, must fluctuate. You don't mean it can fluctuate? 130 00:06:12.000 --> 00:06:14.959 No, I mean must. It's a requirement. Nature literally does 131 00:06:15.000 --> 00:06:16.839 not have a zero setting that it can hold for 132 00:06:16.879 --> 00:06:19.720 a fixed short period of time. A precise energy of 133 00:06:19.800 --> 00:06:23.439 zero for a precise time interval violates the uncertainty principle. 134 00:06:23.680 --> 00:06:26.759 So empty space isn't sitting at zero energy. It can't. 135 00:06:26.920 --> 00:06:31.360 It can't. It's jittering, it's vibrating around zero, frothing, seething, 136 00:06:32.120 --> 00:06:32.720 pick your verb. 137 00:06:32.839 --> 00:06:35.800 And this isn't a measurement problem, right, It's not that 138 00:06:35.879 --> 00:06:38.480 our tools are bad and we just can't detect the stillness. 139 00:06:38.560 --> 00:06:40.720 No, absolutely not. This is one of the hardest things 140 00:06:40.759 --> 00:06:45.000 to grasp about quantum mechanics. The fuzziness is a fundamental 141 00:06:45.000 --> 00:06:49.639 property of reality itself. The universe is inherently uncertain at 142 00:06:49.639 --> 00:06:50.160 this level. 143 00:06:50.639 --> 00:06:52.560 So even if you clear out all the matter, all 144 00:06:52.560 --> 00:06:55.439 the radiation, there's still something there. 145 00:06:55.839 --> 00:06:59.160 The quantum fields are still there, the electromagnetic field, the 146 00:06:59.240 --> 00:07:01.600 Higgs field, all of them. You can't comgri to the fields. 147 00:07:01.600 --> 00:07:04.560 They are the fabric of space, and because of this uncertainty, 148 00:07:04.600 --> 00:07:06.279 those fields are constantly vibrating. 149 00:07:06.319 --> 00:07:09.040 Okay, so we have energy fluctuating in empty space. 150 00:07:09.120 --> 00:07:09.759 It's buzzing. 151 00:07:10.199 --> 00:07:13.839 But Einstein taught us something pretty important about energy, right, 152 00:07:14.120 --> 00:07:16.800 the famous one e mc two two, the. 153 00:07:16.720 --> 00:07:20.279 Most famous equation in history. Energy equals mass times the 154 00:07:20.279 --> 00:07:21.680 speed of light squared. 155 00:07:21.319 --> 00:07:23.560 Which means energy and mass are two sides of the 156 00:07:23.600 --> 00:07:27.879 same coin. They are, for all intents and purposes, interchangeable. 157 00:07:27.319 --> 00:07:30.600 Precisely, And this is where the pop up universe comes 158 00:07:30.600 --> 00:07:34.199 into play. If you have energy fluctuations in the vacuum, 159 00:07:34.560 --> 00:07:35.879 and energy can become. 160 00:07:35.759 --> 00:07:39.639 Mass, then the vacuum isn't just fluctuating with abstract energy. 161 00:07:39.639 --> 00:07:42.839 It's fluctuating with mass with particles. This is the part 162 00:07:42.879 --> 00:07:45.199 that always sounds like science fiction to me. I mean, 163 00:07:45.240 --> 00:07:48.199 it just sounds impossible. You're talking about virtual particles. 164 00:07:47.800 --> 00:07:53.120 Yes, virtual particles, ephemeral, fleeting, but very real. 165 00:07:53.439 --> 00:07:55.959 So let's be very very specific here. I'm looking at 166 00:07:56.000 --> 00:07:57.879 that empty box we talked about, the one we pumped 167 00:07:57.879 --> 00:08:00.959 all the air out of. What is actually happened inside it? 168 00:08:01.199 --> 00:08:01.600 Right now? 169 00:08:01.680 --> 00:08:05.199 Okay, picture a particle and its antiparticle. The classic example 170 00:08:05.240 --> 00:08:08.360 is an electron and a positron, which is an anti electron. Okay, 171 00:08:08.560 --> 00:08:14.120 out of absolutely nowhere. The vacuum spontaneously borrows a tiny 172 00:08:14.120 --> 00:08:16.519 bit of energy from itself to create this pair. They 173 00:08:16.560 --> 00:08:18.399 pop into existence out of nowhere. 174 00:08:18.439 --> 00:08:19.240 There's no source. 175 00:08:19.399 --> 00:08:22.360 The source is the uncertainty of the quantum field itself. 176 00:08:22.519 --> 00:08:26.120 It's a loan from the universe's energy bank. So they appear, 177 00:08:26.319 --> 00:08:28.920 they exist for an incredibly brief moment, and then snap, 178 00:08:29.560 --> 00:08:31.720 they find each other. They could pull back together. 179 00:08:31.439 --> 00:08:33.519 And annihilate, and they give the energy back. 180 00:08:33.559 --> 00:08:36.000 They return the energy they borrowed back to the vacuum. 181 00:08:36.120 --> 00:08:38.200 The books are balanced, so it's like a bank loan, 182 00:08:38.679 --> 00:08:39.799 a cosmic. 183 00:08:39.360 --> 00:08:42.679 Overdraft, a very very high frequency, high risk bank. 184 00:08:42.720 --> 00:08:46.000 Loan, yes, and the uncertainty principle is the bank manager 185 00:08:46.120 --> 00:08:47.639 setting the terms of that loan. 186 00:08:48.360 --> 00:08:51.879 That is a perfect analogy. The rule is the more 187 00:08:52.000 --> 00:08:55.360 energy you borrow, which means the heavier the particles you create, 188 00:08:55.919 --> 00:08:57.320 the faster you have to pay it back. 189 00:08:57.519 --> 00:08:59.639 So you can make a big heavy particle. 190 00:08:59.799 --> 00:09:02.960 Can borrow enough energy to make say a top quark 191 00:09:03.000 --> 00:09:06.039 in an anti top quark, which are incredibly massive, but 192 00:09:06.120 --> 00:09:08.360 you might only have a trillionth of a trillionth of 193 00:09:08.399 --> 00:09:10.639 a second to exist before you have to annihilate and 194 00:09:10.679 --> 00:09:11.240 pay the debt. 195 00:09:11.320 --> 00:09:16.120 That seems incredibly convenient. I have to be honest, Hey, 196 00:09:16.240 --> 00:09:18.679 these particles exist, but they disappear so fast you can't 197 00:09:18.720 --> 00:09:22.159 possibly see them. It feels like a mathematical trick, like 198 00:09:22.240 --> 00:09:25.519 some physicists had a bookkeeping error in their equations and 199 00:09:25.559 --> 00:09:27.519 just gave it a cool name to cover their tracks. 200 00:09:27.679 --> 00:09:31.480 Well those were yeah, virtual particles. Don't worry about them exactly, 201 00:09:31.519 --> 00:09:34.720 and that is the healthy skepticism everyone should have. It 202 00:09:34.759 --> 00:09:37.960 sounds like a cheat code for physics, a fudge factor. 203 00:09:38.399 --> 00:09:42.200 But here's the thing. They are absolutely real. They are 204 00:09:42.240 --> 00:09:46.799 not just math. We have physical, experimental proof that they 205 00:09:46.799 --> 00:09:48.679 are there and that they have consequences. 206 00:09:48.639 --> 00:09:51.080 Way, give me the smoking gun, because if they disappear 207 00:09:51.120 --> 00:09:53.519 in ten twenty one seconds or less, how in the 208 00:09:53.559 --> 00:09:54.559 world are we seeing them. 209 00:09:54.919 --> 00:09:57.080 We don't see them directly, You're right about that. We 210 00:09:57.159 --> 00:09:59.759 see their footprints. We see the effects they have on 211 00:09:59.799 --> 00:10:03.039 the real particles we can see. And the clearest footprint 212 00:10:03.039 --> 00:10:06.000 of all is found in the simplest atom. There is 213 00:10:06.840 --> 00:10:07.840 the hydrogen atom. 214 00:10:08.000 --> 00:10:11.080 The classic one proton, one electron orbiting it right now. 215 00:10:11.120 --> 00:10:14.360 Think about that electron orbiting the nucleus. In the old 216 00:10:14.440 --> 00:10:18.480 classical view, that electron is just a simple negative point charge. 217 00:10:18.519 --> 00:10:20.559 It's a lonely dot moving through a true void. 218 00:10:20.679 --> 00:10:21.480 Sure simple. 219 00:10:21.639 --> 00:10:24.639 But in the quantum world, that electron is moving through 220 00:10:24.639 --> 00:10:27.559 this mosh pit of virtual particles we just described the 221 00:10:27.759 --> 00:10:28.600 seeding foam. 222 00:10:28.720 --> 00:10:30.679 The vacuum is buzzing all around. 223 00:10:30.360 --> 00:10:35.159 It exactly now. The electron is negatively charged. The vacuum, meanwhile, 224 00:10:35.279 --> 00:10:39.679 is constantly popping with these virtual electron positron pairs. The 225 00:10:39.720 --> 00:10:43.960 positive virtual positrons in that foam get attracted to our real. 226 00:10:43.799 --> 00:10:45.519 Electron opposites at fract and. 227 00:10:45.480 --> 00:10:48.600 The negative virtual electrons get repelled. They're pushed away. 228 00:10:48.600 --> 00:10:50.840 So the vacuum is reacting to the guest in the room. 229 00:10:50.960 --> 00:10:53.759 It creates a crowd around it. It forms a polarized 230 00:10:53.799 --> 00:10:58.080 cloud of virtual particles that swarms around the real electron, 231 00:10:58.360 --> 00:11:02.720 and this cloud actually shields the electrons charge, It screens it. 232 00:11:02.840 --> 00:11:04.799 Wait. Wait, so the charge of an electron that we 233 00:11:04.879 --> 00:11:08.039 measure isn't its real fundamental charge. 234 00:11:08.080 --> 00:11:10.240 Correct. When we measure the charge of an electron from 235 00:11:10.240 --> 00:11:14.440 a distance, what we are actually seeing isn't the bear electron. 236 00:11:14.799 --> 00:11:19.120 We are seeing the electron plus this fuzzy polarized cloud 237 00:11:19.279 --> 00:11:21.960 of virtual particles that is dampening its effect. 238 00:11:22.039 --> 00:11:24.759 So the naked electron is actually stronger, much stronger. 239 00:11:24.919 --> 00:11:26.679 But we can never see it naked. We always see 240 00:11:26.720 --> 00:11:27.919 it clothed in the vacuum. 241 00:11:28.000 --> 00:11:30.519 That is wild. It's like a celebrity trying to walk 242 00:11:30.559 --> 00:11:33.360 through a crowd of paparazzi. You can't see the person clearly. 243 00:11:33.399 --> 00:11:35.879 You just see this chaotic entourage moving with them. 244 00:11:36.000 --> 00:11:39.120 That's a perfect analogy, and we can measure this encourage effect. 245 00:11:39.720 --> 00:11:43.120 It subtly changes the energy levels of the electron in 246 00:11:43.159 --> 00:11:46.600 the hydrogen atom. It's an effect called lambshift. 247 00:11:46.039 --> 00:11:47.240 And we can measure that shift. 248 00:11:47.320 --> 00:11:49.559 We can or we can look at something called the 249 00:11:49.600 --> 00:11:52.639 magnetic moment of the electron, basically a measure of how 250 00:11:52.720 --> 00:11:53.559 magnetic it is. 251 00:11:53.639 --> 00:11:55.559 And how precise is this This is where the proof 252 00:11:55.600 --> 00:11:55.919 comes in. 253 00:11:56.039 --> 00:11:59.159 This is it. When we calculate what the magnetic strength 254 00:11:59.200 --> 00:12:03.679 of an electron should be using just simple quantum mechanics, 255 00:12:04.080 --> 00:12:06.519 you know, without the virtual particles, we get a number, 256 00:12:06.679 --> 00:12:08.919 a very precise number, okay, But when we go into 257 00:12:08.919 --> 00:12:11.919 the lab and we measure it, the experimental value is 258 00:12:11.919 --> 00:12:14.440 slightly different. It's a tiny bit stronger, and. 259 00:12:14.360 --> 00:12:17.399 The difference matches the effects of the cloud to. 260 00:12:17.360 --> 00:12:21.840 An astonishing, almost unbelievable degree. When we use the full 261 00:12:21.879 --> 00:12:25.879 theory of quantum electrodynamics QED to calculate the influence of 262 00:12:25.879 --> 00:12:30.600 that virtual cloud, the theoretical prediction matches the experimental measurement to. 263 00:12:30.639 --> 00:12:32.399 Parts per billion parts per billion. 264 00:12:32.559 --> 00:12:35.320 It is often cited as the most precise and successful 265 00:12:35.360 --> 00:12:38.039 prediction in the entire history of science. 266 00:12:38.480 --> 00:12:41.480 Wow. So, if virtual particles were just a math trick, 267 00:12:42.080 --> 00:12:44.000 that calculation would be completely wrong. 268 00:12:44.080 --> 00:12:46.159 It would be completely off. It wouldn't even be close. Yeah, 269 00:12:46.240 --> 00:12:48.480 the fact that it matches so perfectly tells us that 270 00:12:48.519 --> 00:12:51.960 the vacuum is alive, that cloud is real. You me 271 00:12:52.200 --> 00:12:54.879 the chair you're sitting on. Every single electron in our 272 00:12:54.879 --> 00:12:57.480 bodies is walking around with its own little ghost entourage 273 00:12:57.519 --> 00:12:58.799 from the vacuum. 274 00:12:58.840 --> 00:13:01.919 Okay, I'm sold on the app But that's all microscopic, 275 00:13:01.960 --> 00:13:04.440 it's tiny. Is there any way to see the force 276 00:13:04.519 --> 00:13:08.600 of nothing on a scale we can actually, you know, visualize. 277 00:13:08.639 --> 00:13:11.000 Can nothing actually push a physical object? 278 00:13:11.519 --> 00:13:14.039 It can? And this brings us to one of my 279 00:13:14.159 --> 00:13:18.080 absolute favorite phenomena in all of physics, the Casimir effect. 280 00:13:18.279 --> 00:13:20.879 This was discovered theoretically back in nineteen forty eight by 281 00:13:20.919 --> 00:13:22.759 Hendrick Casimir ra Yes, and. 282 00:13:22.759 --> 00:13:24.159 At the time people thought it was just a bit 283 00:13:24.200 --> 00:13:28.480 of a mathematical curiosity. The setup itself is deceptively simple. 284 00:13:28.840 --> 00:13:32.879 Imagine you take two metal plates, perfectly flat, perfectly reflective, 285 00:13:32.919 --> 00:13:34.720 and completely uncharged. 286 00:13:34.320 --> 00:13:37.320 So no electricity, no magnetism, none at all. 287 00:13:37.399 --> 00:13:39.360 You put them in a perfect vacuum, and you place 288 00:13:39.399 --> 00:13:42.000 them incredibly close together. We're talking micrometers apart. 289 00:13:42.279 --> 00:13:47.519 Okay, so two neutral plates floating in the dark. Logic 290 00:13:47.600 --> 00:13:49.879 says they should just sit there, they have no reason 291 00:13:49.919 --> 00:13:51.120 to move, nothing should happen. 292 00:13:51.279 --> 00:13:54.799 Classical logic says nothing should happen. But Casimir did the math. 293 00:13:55.000 --> 00:13:57.840 He included the quantum vacuum, and he calculated that they 294 00:13:57.840 --> 00:14:01.000 would actually be pushed together and invisible force would slam 295 00:14:01.039 --> 00:14:01.559 them shut. 296 00:14:01.759 --> 00:14:05.080 Why if they aren't magnetic, what's pushing them? Where does 297 00:14:05.120 --> 00:14:05.960 the force come from. 298 00:14:06.200 --> 00:14:09.480 It's the vacuum itself. Yeah, the pressure of the void. 299 00:14:10.200 --> 00:14:13.200 To understand why, we have to stop thinking of these 300 00:14:13.279 --> 00:14:15.840 virtual particles as little balls for a second and start 301 00:14:15.840 --> 00:14:18.879 thinking of them as waves. Quantum mechanics says, every particle 302 00:14:18.960 --> 00:14:20.360 is also a wave, right. 303 00:14:20.279 --> 00:14:22.519 The old wave particle duality. I'm with you. 304 00:14:23.039 --> 00:14:26.600 So in the open space outside the plates, virtual waves 305 00:14:26.639 --> 00:14:30.320 of any size, any wavelength can exist. You can have big, long, 306 00:14:30.480 --> 00:14:35.240 rolling waves, tiny short, choppy waves. Everything fits. The ocean's 307 00:14:35.279 --> 00:14:36.080 wide open. 308 00:14:36.039 --> 00:14:37.840 Right, unlimited possibilities. 309 00:14:37.960 --> 00:14:40.200 But between the plates it's a tight squeeze. You've created 310 00:14:40.200 --> 00:14:42.679 a boundary. It's like a guitar string. You can only 311 00:14:42.679 --> 00:14:45.480 place certain notes, certain wavelengths that fit perfectly between the 312 00:14:45.519 --> 00:14:46.120 two ends. 313 00:14:46.360 --> 00:14:49.120 Ah, I see, you can't fit a wave that's bigger 314 00:14:49.120 --> 00:14:51.080 than the gap between the plates exactly. 315 00:14:51.159 --> 00:14:54.679 You have physically excluded all the big long wavelength of 316 00:14:54.720 --> 00:14:58.000 virtual particles from the space between the plates. You filtered 317 00:14:58.000 --> 00:14:58.320 the mouth. 318 00:14:58.399 --> 00:15:00.679 So now you have an imbalance huge imbalance. 319 00:15:00.960 --> 00:15:03.559 You have a full vacuum pushing on the place from 320 00:15:03.600 --> 00:15:06.000 the outside. All the possible waves are banging against them, 321 00:15:06.279 --> 00:15:09.480 and you have a restricted vacuum pushing from the inside 322 00:15:09.759 --> 00:15:11.080 only the small waves that can fit. 323 00:15:11.240 --> 00:15:12.559 So there's more pressure from the outside. 324 00:15:12.600 --> 00:15:16.440 It's a radiation pressure difference exerted by nothing. There is 325 00:15:16.480 --> 00:15:19.399 literally more stuff popping in and out of existence and 326 00:15:19.480 --> 00:15:22.559 banging against the plates from the outside than from the inside. 327 00:15:23.000 --> 00:15:26.200 So the net effect is a force pushing the plates together. 328 00:15:26.320 --> 00:15:30.919 That is actually somewhat terrifying. That empty space exerts real 329 00:15:31.200 --> 00:15:34.360 physical pressure. If you can exclude enough of it, it 330 00:15:34.360 --> 00:15:35.080 will crush you. 331 00:15:35.679 --> 00:15:37.879 And we've measured it. Took a long time. The force 332 00:15:37.960 --> 00:15:40.360 is incredibly tiny and hard to detect, but in the 333 00:15:40.440 --> 00:15:44.559 nineteen nineties it was confirmed definitively. It's a real force. 334 00:15:44.879 --> 00:15:47.000 And you know from modern engineers this isn't just a 335 00:15:47.000 --> 00:15:51.360 fun theory. Oh how so think about nanotechnology or memes, 336 00:15:51.440 --> 00:15:56.799 microelectro mechanical systems. These are tiny little machines, gears and 337 00:15:56.879 --> 00:15:58.159 switches the size of dust. 338 00:15:58.200 --> 00:16:00.919 Motes like the accelerometer in my phone that detects when 339 00:16:00.960 --> 00:16:01.440 I turn. 340 00:16:01.279 --> 00:16:04.600 It exactly that when you build machines that small, the 341 00:16:04.639 --> 00:16:08.559 parts are incredibly close together, and for years engineers found 342 00:16:08.559 --> 00:16:12.519 that sometimes these tiny parts would just stick. They would 343 00:16:12.519 --> 00:16:15.679 clamp together for no apparent reason and get stuck. They 344 00:16:15.720 --> 00:16:18.480 called it stiction stiiction, and a big component of that 345 00:16:18.559 --> 00:16:22.799 stiction is the Casimir force. The vacuum is literally trying 346 00:16:22.840 --> 00:16:25.200 to weld your machine together, So you have to design 347 00:16:25.240 --> 00:16:28.360 your phone to actively fight against the pressure of the void. 348 00:16:28.720 --> 00:16:31.840 So nothing is now an engineering constraint on our technology. 349 00:16:31.960 --> 00:16:32.840 It absolutely is. 350 00:16:33.000 --> 00:16:35.960 Okay, so we've established the vacuum is energetic, it's buzzing, 351 00:16:36.039 --> 00:16:39.240 it's real. It pushes plates around. But this leads to 352 00:16:39.320 --> 00:16:42.559 a massive, massive problem, doesn't it. I've heard this referred 353 00:16:42.600 --> 00:16:44.200 to as the vacuum catastrophe. 354 00:16:44.240 --> 00:16:48.480 Oh yes, the cosmological constant problem. This is where this beautiful, 355 00:16:48.519 --> 00:16:52.600 elegant theory crashes headfirst into reality and explodes in a 356 00:16:52.600 --> 00:16:53.240 ball of fire. 357 00:16:53.559 --> 00:16:56.159 Let's get into this. We know there's energy in the vacuum. 358 00:16:56.200 --> 00:16:58.000 You called it zero point energy, right. 359 00:16:57.919 --> 00:17:01.679 Zero point just means the lowest possible energy state, As 360 00:17:01.759 --> 00:17:05.640 we said, thanks to Heisenberg, it's not zero. Now, if 361 00:17:05.680 --> 00:17:08.920 take queum field theory seriously, you should be able to 362 00:17:08.920 --> 00:17:13.039 calculate how much energy is in say a coffee cup's 363 00:17:13.079 --> 00:17:14.039 worth of empty space. 364 00:17:14.160 --> 00:17:15.759 You just sum up all those fluctuations. 365 00:17:15.839 --> 00:17:18.240 You add up all the virtual particles, all the waves, 366 00:17:18.319 --> 00:17:21.960 all the jitters from all the different fields. And when 367 00:17:22.000 --> 00:17:25.480 physicists do this, they get a number, a truly mind 368 00:17:25.519 --> 00:17:27.920 bogglingly astronomically huge number. 369 00:17:28.039 --> 00:17:29.880 How huge are we talking, Well, let's put. 370 00:17:29.759 --> 00:17:33.200 It in context. Einstein told us energy has mass, and 371 00:17:33.240 --> 00:17:36.599 gravity pulls on mass. So if the vacuum is full 372 00:17:36.640 --> 00:17:39.240 of this enormous amount of energy, it should have an 373 00:17:39.319 --> 00:17:42.519 enormous gravitational pull, right, it should weigh something a lot, 374 00:17:42.599 --> 00:17:46.200 an incredible amount. If the vacuum really contained the amount 375 00:17:46.240 --> 00:17:49.240 of energy, the theory predicts, space itself would have so 376 00:17:49.319 --> 00:17:52.119 much mass energy that it would have instantly crushed the 377 00:17:52.279 --> 00:17:55.119 entire universe into a black hole fractions of a second 378 00:17:55.160 --> 00:17:56.000 after the Big Bang. 379 00:17:56.200 --> 00:18:00.400 Okay, well, looking around, I can confirm that did not happen. 380 00:18:00.559 --> 00:18:03.480 I'm not currently spaghettified. The universe is still here. 381 00:18:03.440 --> 00:18:06.319 And not only is it here, it's expanding. In fact, 382 00:18:06.440 --> 00:18:10.400 observations of distant supernovae tell us it's accelerating. The expansion 383 00:18:10.440 --> 00:18:11.240 is speeding up. 384 00:18:11.119 --> 00:18:13.599 And that's driven by dark energy, which is, for. 385 00:18:13.599 --> 00:18:16.799 All intents and purposes, the measured weight of the vacuum. 386 00:18:16.880 --> 00:18:19.599 It's the observed energy density of space that is pushing 387 00:18:19.599 --> 00:18:20.440 the universe apart. 388 00:18:20.599 --> 00:18:23.960 So we have the theoretical weight what the math says 389 00:18:24.000 --> 00:18:26.599 the vacuum should weigh, and we have the measured weight 390 00:18:26.920 --> 00:18:29.599 what the telescope say it actually weighs. What's the difference. 391 00:18:30.000 --> 00:18:33.759 The discrepancy between the theoretical prediction and the observed value 392 00:18:34.079 --> 00:18:36.200 is about one hundred and twenty orders of magnitude. 393 00:18:36.400 --> 00:18:38.279 I'm sorry, did you say one hundred and twenty as 394 00:18:38.279 --> 00:18:40.759 in a one with one hundred and twenty zeros after it? 395 00:18:40.799 --> 00:18:43.640 I did a one followed by one hundred and twenty zeros. 396 00:18:43.799 --> 00:18:46.240 That is, I don't even have an analogy for that. 397 00:18:46.480 --> 00:18:48.880 If I was an architect and I calculated the load 398 00:18:48.920 --> 00:18:51.160 bearing capacity of a bridge and I was wrong by 399 00:18:51.200 --> 00:18:53.920 one hundred and twenty orders of magnitude, I wouldn't just 400 00:18:53.920 --> 00:18:56.559 be fired. I'd be arrested. The bridge wouldn't just collapse, 401 00:18:56.559 --> 00:18:59.160