1 00:00:08,720 --> 00:00:12,760 Speaker 1: Hey, Daniel, can you pass through walls? No? Keep trying 2 00:00:12,840 --> 00:00:14,880 Speaker 1: and just keep getting more bumps on my head? How 3 00:00:14,880 --> 00:00:17,160 Speaker 1: about can you bean too pleased at the same time? 4 00:00:17,360 --> 00:00:19,560 Speaker 1: Sometimes it feels like I'm supposed to be but I've 5 00:00:19,600 --> 00:00:21,720 Speaker 1: never actually managed it. So I guess you're not a 6 00:00:22,000 --> 00:00:25,520 Speaker 1: quantum object. No. Actually, I'm quite classical. But you're a 7 00:00:25,560 --> 00:00:28,520 Speaker 1: particle physicists. Aren't you made of particles? And aren't those 8 00:00:28,560 --> 00:00:33,640 Speaker 1: particles quantum mechanical? I study particles and I'm made of particles, 9 00:00:33,640 --> 00:00:37,839 Speaker 1: but I follow the rules of classical physics. Classic. I 10 00:00:37,880 --> 00:00:56,880 Speaker 1: mean you're classic, Daniel. I'm not new Coke Daniel. I 11 00:00:56,920 --> 00:00:59,960 Speaker 1: am more hammad cartoonists and the creator of PhD comics. 12 00:01:00,320 --> 00:01:04,200 Speaker 1: I'm Daniel. I'm a particle physicist, but I'm quite classical 13 00:01:04,400 --> 00:01:06,640 Speaker 1: in my tastes. Are you a fan of classical music 14 00:01:06,680 --> 00:01:08,680 Speaker 1: and it's better than quantum music? Let me tell you 15 00:01:09,520 --> 00:01:12,000 Speaker 1: that's a new genre to mak a new category at 16 00:01:12,000 --> 00:01:14,039 Speaker 1: the Grammy. Oh I wish it was a new genre, 17 00:01:14,080 --> 00:01:16,399 Speaker 1: but I'm sure if we type it into Google we 18 00:01:16,480 --> 00:01:19,000 Speaker 1: will find something for quantum music. I feel like that's 19 00:01:19,000 --> 00:01:22,200 Speaker 1: all music these days. It's both good and bad. It's 20 00:01:22,280 --> 00:01:26,880 Speaker 1: kind of incoherent. It's both original and stale. Welcome to 21 00:01:26,880 --> 00:01:29,840 Speaker 1: our podcast, Daniel and Jorge Explain the Universe, a production 22 00:01:29,920 --> 00:01:32,640 Speaker 1: of My Heart Radio in which we explore everything in 23 00:01:32,680 --> 00:01:35,200 Speaker 1: the universe and try to make sense of it. We 24 00:01:35,280 --> 00:01:37,640 Speaker 1: try to understand how things move in our world and 25 00:01:37,680 --> 00:01:40,960 Speaker 1: how tiny particles move. We try to understand the rules 26 00:01:41,200 --> 00:01:44,600 Speaker 1: of the universe, whether they govern supernovas and black holes 27 00:01:44,720 --> 00:01:47,720 Speaker 1: or tiny little electrons, and we try to make sure 28 00:01:47,800 --> 00:01:50,520 Speaker 1: that you understand them. Yeah, because we try to make 29 00:01:50,560 --> 00:01:55,280 Speaker 1: this podcast a super position of both fun and real science, 30 00:01:56,240 --> 00:01:59,240 Speaker 1: physics and banana jokes. You often think those two can't 31 00:01:59,240 --> 00:02:01,800 Speaker 1: be in the same place. Said the same time, what 32 00:02:01,920 --> 00:02:04,520 Speaker 1: makes you say that you haven't met any fun physicists. 33 00:02:04,560 --> 00:02:07,040 Speaker 1: You mean the physicists is fun, or they know how 34 00:02:07,040 --> 00:02:09,840 Speaker 1: to have fun, or just doing physics is fun. Why 35 00:02:09,919 --> 00:02:12,320 Speaker 1: doesn't everybody see that? Come on, I think that's the 36 00:02:12,360 --> 00:02:15,639 Speaker 1: problems and that's the problem. But yeah, it's a weird 37 00:02:15,840 --> 00:02:18,640 Speaker 1: and strange universe out there, and so we like to 38 00:02:18,680 --> 00:02:21,160 Speaker 1: talk about all of the things and make it weird 39 00:02:21,200 --> 00:02:24,600 Speaker 1: and strange. It's pretty unintuitive the universe it is, and 40 00:02:24,680 --> 00:02:27,600 Speaker 1: physics has done a great job of building this edifice 41 00:02:27,639 --> 00:02:30,720 Speaker 1: to help us understand the way the universe really is, 42 00:02:30,840 --> 00:02:33,040 Speaker 1: not the way we think the universe should be or 43 00:02:33,160 --> 00:02:35,480 Speaker 1: might be, or the way that makes sense to us 44 00:02:35,800 --> 00:02:38,760 Speaker 1: based on our limited experience, but actually revealing to us 45 00:02:38,960 --> 00:02:42,160 Speaker 1: the true nature of reality. But sometimes what we learn 46 00:02:42,320 --> 00:02:45,760 Speaker 1: is pretty hard to swallow. Yeah, and specifically quantum mechanics. 47 00:02:45,760 --> 00:02:49,000 Speaker 1: I feel like that really trips people up. It trips 48 00:02:49,040 --> 00:02:50,640 Speaker 1: me up, for sure, And it's kind of hard to 49 00:02:50,680 --> 00:02:53,799 Speaker 1: wrap your head around all of the weird, kind of 50 00:02:54,040 --> 00:02:57,800 Speaker 1: unintuitive phenomenon that happens at the quantum level. Yeah, it 51 00:02:57,880 --> 00:03:01,079 Speaker 1: is pretty weird because quantum particles seem to be following 52 00:03:01,160 --> 00:03:03,919 Speaker 1: different rules. They seem to be able to break rules 53 00:03:03,960 --> 00:03:06,840 Speaker 1: that are hard and fast for things like baseballs and 54 00:03:06,960 --> 00:03:09,959 Speaker 1: basketballs and scoops of ice cream. And that's a hard 55 00:03:09,960 --> 00:03:12,600 Speaker 1: thing to understand because it's weird and it's new. It's 56 00:03:12,639 --> 00:03:15,519 Speaker 1: also hard to understand, like why are there different rules? 57 00:03:15,520 --> 00:03:18,240 Speaker 1: And you know, what's the difference between an electron and 58 00:03:18,320 --> 00:03:20,720 Speaker 1: a baseball? You know, where is the sort of threshold 59 00:03:20,800 --> 00:03:23,320 Speaker 1: between those two where the quantum rules take over or 60 00:03:23,320 --> 00:03:25,600 Speaker 1: the classical rules take over. Yeah, it is kind of 61 00:03:25,600 --> 00:03:28,120 Speaker 1: weird that, you know, things are so weird at that level, 62 00:03:28,400 --> 00:03:31,360 Speaker 1: at the microscopic level, but then once you scale up, 63 00:03:31,560 --> 00:03:37,600 Speaker 1: things feel more gosh normal, more solid, less uncertain, or 64 00:03:37,640 --> 00:03:40,800 Speaker 1: at least more familiar. Right. Science is all about delving 65 00:03:40,840 --> 00:03:43,760 Speaker 1: into the unknown, and typically we try to explain the 66 00:03:43,840 --> 00:03:47,400 Speaker 1: unknown in terms of the known, but that fails if 67 00:03:47,440 --> 00:03:50,839 Speaker 1: the unknown is something really new, something different, something that's 68 00:03:51,000 --> 00:03:54,600 Speaker 1: fundamentally can't be described by what we already know. We've 69 00:03:54,600 --> 00:03:57,320 Speaker 1: often talked about how physics is like exploring the universe, 70 00:03:57,440 --> 00:03:59,800 Speaker 1: but it's just been studying the tail of the elephant, 71 00:04:00,120 --> 00:04:01,600 Speaker 1: and when you look at the rest of the elephant, 72 00:04:01,600 --> 00:04:03,920 Speaker 1: it's not always true that what you learn from the 73 00:04:03,960 --> 00:04:06,280 Speaker 1: tail can help you understand the rest of the elephant. 74 00:04:06,440 --> 00:04:09,640 Speaker 1: Sometimes you really do discover something weird and different. Yeah, 75 00:04:09,720 --> 00:04:13,560 Speaker 1: but is that elephant quantum mechanical, Daniel, Is it really 76 00:04:13,600 --> 00:04:17,719 Speaker 1: there or not there? It's a theoretical thought experiment elephant. 77 00:04:17,760 --> 00:04:21,000 Speaker 1: So it's just totally not there. That's classically non existent. 78 00:04:21,560 --> 00:04:25,000 Speaker 1: Al Right. Well, that connection between the quantum world and 79 00:04:25,080 --> 00:04:28,960 Speaker 1: our regular, everyday world is what we'll be exploring today 80 00:04:29,040 --> 00:04:31,599 Speaker 1: on this episode to be on the podcast. We'll be 81 00:04:31,640 --> 00:04:41,719 Speaker 1: asking the question what is quantum decoherence? That's hopefully a 82 00:04:41,800 --> 00:04:46,440 Speaker 1: coherent question, yes, and quantum decoherence is the key concept 83 00:04:46,720 --> 00:04:50,919 Speaker 1: to understanding the answer to this question. Why do big 84 00:04:50,960 --> 00:04:54,599 Speaker 1: objects not seem to follow quantum rules? What is the 85 00:04:54,640 --> 00:04:58,640 Speaker 1: difference between quantum objects and big objects? Where is the threshold? 86 00:04:58,640 --> 00:05:01,160 Speaker 1: Why do we seem to have two sets of rules 87 00:05:01,360 --> 00:05:02,960 Speaker 1: or is it just that one set of rules sort 88 00:05:02,960 --> 00:05:06,000 Speaker 1: of morpse into the other. Right, it's an important concept, 89 00:05:06,080 --> 00:05:08,840 Speaker 1: and it seems to be sort of related to this 90 00:05:09,040 --> 00:05:13,200 Speaker 1: idea of quantum measurements. I think maybe that's something that 91 00:05:13,240 --> 00:05:15,840 Speaker 1: if you've heard of quantum mechanics or have talked about 92 00:05:15,880 --> 00:05:18,760 Speaker 1: it or seen any videos about it or read about it, 93 00:05:18,760 --> 00:05:20,880 Speaker 1: it's something that seems to be important that you know 94 00:05:21,040 --> 00:05:23,719 Speaker 1: things are quantum, but then when you poke at them 95 00:05:23,880 --> 00:05:26,719 Speaker 1: or measure them or try to look at them, things 96 00:05:26,800 --> 00:05:29,240 Speaker 1: collapse for some reason. Yeah, this is a big and 97 00:05:29,320 --> 00:05:33,920 Speaker 1: still totally unsolved problem in quantum mechanics. Quantum mechanical things 98 00:05:33,960 --> 00:05:38,120 Speaker 1: can have like multiple possibilities, but we don't observe multiple possibilities. 99 00:05:38,120 --> 00:05:40,520 Speaker 1: When you poke an electron, as you say, it picks 100 00:05:40,560 --> 00:05:43,280 Speaker 1: one of them, and we don't really understand how that happens, 101 00:05:43,320 --> 00:05:45,720 Speaker 1: how one of them gets picked, and actually when that 102 00:05:45,760 --> 00:05:48,479 Speaker 1: picking happens, you know, Does it happen when your finger 103 00:05:48,600 --> 00:05:50,600 Speaker 1: touches the electron? Does it happen when you look at 104 00:05:50,600 --> 00:05:53,839 Speaker 1: the results? That happens somewhere in between. That's a really 105 00:05:53,880 --> 00:05:57,840 Speaker 1: interesting and hard problem, and it's related to quantum decoherence, 106 00:05:57,880 --> 00:06:00,480 Speaker 1: but they're not quite the same thing. To today, we'll 107 00:06:00,480 --> 00:06:03,159 Speaker 1: try to explain what quantum decoherence is, how it helps 108 00:06:03,200 --> 00:06:06,200 Speaker 1: us understand the difference between quantum and classical objects. But 109 00:06:06,240 --> 00:06:08,520 Speaker 1: it's important to understand that it doesn't actually solve this 110 00:06:08,600 --> 00:06:11,720 Speaker 1: problem of the quantum measurement. Is that what happens when 111 00:06:11,720 --> 00:06:14,560 Speaker 1: you pull on the tail of the elephant, things get 112 00:06:14,600 --> 00:06:18,320 Speaker 1: real real quick. You get quantum stomped. It makes quantum 113 00:06:18,400 --> 00:06:20,240 Speaker 1: music out of you. All right, Well, this is an 114 00:06:20,240 --> 00:06:23,200 Speaker 1: interesting question what is quantum decoherence? And so as usual 115 00:06:23,240 --> 00:06:25,440 Speaker 1: we were wondering how many people out there in the 116 00:06:25,600 --> 00:06:28,599 Speaker 1: real world know what it means. So as usual, Daniel 117 00:06:28,640 --> 00:06:30,799 Speaker 1: went other into the wilds of the internet to ask 118 00:06:31,520 --> 00:06:34,680 Speaker 1: what is quantum decoherence? So thank you very much to 119 00:06:34,760 --> 00:06:38,320 Speaker 1: everybody who will volunteered your speculation for the podcast. If 120 00:06:38,400 --> 00:06:40,960 Speaker 1: you would like to volunteer for a future podcast, please 121 00:06:41,040 --> 00:06:44,000 Speaker 1: write to us. Two questions at Daniel and Jorge dot com. 122 00:06:44,160 --> 00:06:46,039 Speaker 1: Think about it for a second, soone ask you what 123 00:06:46,279 --> 00:06:50,400 Speaker 1: quantum decoherence is. What would you say it is, or 124 00:06:50,440 --> 00:06:53,680 Speaker 1: at least guess it is. Here's what people had to say. 125 00:06:53,880 --> 00:06:57,000 Speaker 1: I'm not sure if I recognized this right, but I 126 00:06:57,040 --> 00:07:00,760 Speaker 1: think decoherence is about how the quantum and the normal 127 00:07:00,839 --> 00:07:05,799 Speaker 1: little few collide, so how we can map quantum effects 128 00:07:05,839 --> 00:07:10,520 Speaker 1: into all reality. Since coherent means to make sense, I'm 129 00:07:10,560 --> 00:07:16,280 Speaker 1: thinking quantum decoherence is when quantum particles can't logically follow 130 00:07:16,840 --> 00:07:19,160 Speaker 1: the rules of the universe, of the constants of the universe, 131 00:07:19,320 --> 00:07:22,280 Speaker 1: or something of the nature. I'm not sure what quantum 132 00:07:22,320 --> 00:07:27,240 Speaker 1: decoherence is, but I think it might be wave function collapse, 133 00:07:27,360 --> 00:07:32,080 Speaker 1: which is how the wave function of a quantity and 134 00:07:32,120 --> 00:07:36,120 Speaker 1: a quantum system collapses when you measure that quantity. I 135 00:07:36,160 --> 00:07:40,720 Speaker 1: don't know what quantum decoherence is, but my guess would 136 00:07:40,800 --> 00:07:45,679 Speaker 1: be that it is the occurrence of something totally inconsistent 137 00:07:46,600 --> 00:07:50,400 Speaker 1: that disrupts the quantum realm. It's got me thinking of 138 00:07:50,600 --> 00:07:53,160 Speaker 1: something to do with quantum entanglement. All right, Some pre 139 00:07:53,760 --> 00:07:57,000 Speaker 1: coherent answers for the most part, or at least coherent 140 00:07:57,040 --> 00:08:01,200 Speaker 1: in there not knowing what it is. Nobody actually quite 141 00:08:01,280 --> 00:08:03,240 Speaker 1: nailed it. But you know, people are in the vicinity, 142 00:08:03,360 --> 00:08:06,680 Speaker 1: and they seem to understand that there's a concept of coherence, 143 00:08:06,720 --> 00:08:09,480 Speaker 1: at least in quantum mechanics. Somebody said that it is 144 00:08:09,520 --> 00:08:13,400 Speaker 1: sort of where the real world and the normal world collide. 145 00:08:14,240 --> 00:08:16,360 Speaker 1: I guess they do, maybe think it has something to 146 00:08:16,400 --> 00:08:19,560 Speaker 1: do with the connection between the quantum world and our 147 00:08:19,600 --> 00:08:21,920 Speaker 1: everyday experience. Yeah, and that one is the closest I 148 00:08:21,960 --> 00:08:23,880 Speaker 1: think to the right answer, to the right way of 149 00:08:23,880 --> 00:08:27,000 Speaker 1: thinking about it. Quantum to coherence, in brief is the 150 00:08:27,080 --> 00:08:31,000 Speaker 1: idea that explains how quantum objects look like classical objects 151 00:08:31,000 --> 00:08:33,040 Speaker 1: when they get really big and messy. All right, well, 152 00:08:33,120 --> 00:08:35,839 Speaker 1: let's jump into a Daniel and I guess let's start 153 00:08:35,960 --> 00:08:39,360 Speaker 1: with just a quick recap of quantum of a small 154 00:08:39,400 --> 00:08:43,160 Speaker 1: subject called quantum physics. You know, what is it that 155 00:08:43,320 --> 00:08:46,600 Speaker 1: we actually call quantum and how can we kind of 156 00:08:46,640 --> 00:08:49,720 Speaker 1: describe those effects? So the thing to understand is that 157 00:08:49,760 --> 00:08:53,439 Speaker 1: when you look at really small objects, things like electrons 158 00:08:53,600 --> 00:08:57,240 Speaker 1: or photons or individuals tiny particles, they seem to be 159 00:08:57,280 --> 00:09:01,839 Speaker 1: following rules that don't apply to bigger objects like baseballs 160 00:09:01,880 --> 00:09:06,640 Speaker 1: and Basketball's right, and the key concept to understand when 161 00:09:06,640 --> 00:09:10,160 Speaker 1: thinking about these tiny particles is that they're not just particles. 162 00:09:10,160 --> 00:09:13,240 Speaker 1: They're not like tiny versions of a baseball. They're not 163 00:09:13,320 --> 00:09:17,120 Speaker 1: just like miniaturize little blobs of stuff flying through space. 164 00:09:17,400 --> 00:09:20,120 Speaker 1: Right when people were first thinking about the atom, for example, 165 00:09:20,160 --> 00:09:22,920 Speaker 1: they were thinking about the electron like orbiting the nucleus 166 00:09:23,000 --> 00:09:25,720 Speaker 1: like a tiny planet around the star. But we pretty 167 00:09:25,800 --> 00:09:29,160 Speaker 1: quickly figured out that was impossible because if an electron 168 00:09:29,280 --> 00:09:32,079 Speaker 1: orbits and nucleus, then it's going to give off radiation 169 00:09:32,160 --> 00:09:35,400 Speaker 1: because it's accelerating, it's giving off radiation. And they did 170 00:09:35,400 --> 00:09:37,960 Speaker 1: the calculation and discovered, well, that would collapse in like 171 00:09:38,120 --> 00:09:40,480 Speaker 1: a hundred billions of a second because they would lose 172 00:09:40,520 --> 00:09:42,960 Speaker 1: all of his energy. And so instead they had to 173 00:09:42,960 --> 00:09:46,320 Speaker 1: have a new idea for what controls and electron, what 174 00:09:46,440 --> 00:09:49,840 Speaker 1: defines what an electron does and how it interacts, and 175 00:09:49,840 --> 00:09:52,680 Speaker 1: so instead they try to use like wave like properties 176 00:09:52,679 --> 00:09:55,319 Speaker 1: to describe it. So you've probably heard this phrase called 177 00:09:55,480 --> 00:09:58,840 Speaker 1: the wave function. The wave function is just a mathematical 178 00:09:58,880 --> 00:10:01,719 Speaker 1: tool that helps us under and what an electron is 179 00:10:01,800 --> 00:10:04,520 Speaker 1: likely to do. And the key concept is that the 180 00:10:04,559 --> 00:10:07,720 Speaker 1: wave function tells you where a particle is likely to 181 00:10:07,760 --> 00:10:10,560 Speaker 1: be and where it's not likely to be. Sean Carroll 182 00:10:10,600 --> 00:10:13,439 Speaker 1: says that the wave function is the dope ist name 183 00:10:13,480 --> 00:10:15,880 Speaker 1: in the world for one of the most profound things 184 00:10:15,960 --> 00:10:18,720 Speaker 1: in the universe, which really made me laugh. Well, dope 185 00:10:18,840 --> 00:10:21,680 Speaker 1: and profound go hand in hand. I think like physics 186 00:10:21,679 --> 00:10:24,280 Speaker 1: and fun, right, Yeah, well, yeah, I think that is 187 00:10:24,320 --> 00:10:28,360 Speaker 1: maybe the hardest thing to grasp about quantum mechanics and physics. 188 00:10:28,400 --> 00:10:31,040 Speaker 1: You know, I think everyone sort of grows up at 189 00:10:31,120 --> 00:10:34,480 Speaker 1: Leaston's early in school and definitely in popular culture. You know, 190 00:10:34,559 --> 00:10:37,320 Speaker 1: the depiction, like pictures of an atom always look like 191 00:10:37,520 --> 00:10:39,800 Speaker 1: little planetary systems, you know, like a bunch of little 192 00:10:39,800 --> 00:10:43,679 Speaker 1: balls in the middle cluster together, and then other little 193 00:10:43,679 --> 00:10:47,360 Speaker 1: balls kind of swinging around in large orbits and rings 194 00:10:47,400 --> 00:10:50,080 Speaker 1: around that. And that's the picture that we have about 195 00:10:50,120 --> 00:10:52,720 Speaker 1: the atom. But you're saying, at some point we figured 196 00:10:52,760 --> 00:10:57,800 Speaker 1: out that's not possible, like that that doesn't make sense. Yeah, exactly. 197 00:10:57,840 --> 00:11:01,240 Speaker 1: It's not like the electron has a trajectory, has a 198 00:11:01,280 --> 00:11:04,320 Speaker 1: path and we just don't know it. It doesn't actually 199 00:11:04,440 --> 00:11:07,319 Speaker 1: have a path that doesn't have like a position at 200 00:11:07,360 --> 00:11:10,560 Speaker 1: every moment in time. Instead, what it has is this 201 00:11:10,640 --> 00:11:13,600 Speaker 1: quantum wave that the quantum wave behaves all sorts of 202 00:11:13,840 --> 00:11:16,719 Speaker 1: normal wave like rules. But what it does is tell 203 00:11:16,800 --> 00:11:19,600 Speaker 1: us where the electron is likely to be, and so 204 00:11:19,640 --> 00:11:22,000 Speaker 1: the electron is likely to be here and it's likely 205 00:11:22,040 --> 00:11:24,400 Speaker 1: to be there now. Sometimes people say that means that 206 00:11:24,440 --> 00:11:27,719 Speaker 1: the electron is in two places at once, but that's 207 00:11:27,760 --> 00:11:30,360 Speaker 1: not actually correct. It means it has the probability to 208 00:11:30,400 --> 00:11:34,319 Speaker 1: be here or there, and those in both probabilities can 209 00:11:34,440 --> 00:11:36,840 Speaker 1: exist at the same time. It doesn't mean it's actually 210 00:11:36,960 --> 00:11:39,920 Speaker 1: in both places at once. If you ask the electron 211 00:11:40,000 --> 00:11:43,000 Speaker 1: where are you, then it collapses as we talked about earlier, 212 00:11:43,080 --> 00:11:45,600 Speaker 1: It picks one place or the other. But the wave 213 00:11:45,679 --> 00:11:48,719 Speaker 1: function describes what's likely to happen. Well, I guess you 214 00:11:48,960 --> 00:11:51,760 Speaker 1: mentioned before that it has a dopey name. Why do 215 00:11:51,800 --> 00:11:53,760 Speaker 1: you think it's a bad name, And what would you 216 00:11:53,760 --> 00:11:56,400 Speaker 1: have called it if not the wave function? And why 217 00:11:56,480 --> 00:11:59,480 Speaker 1: is it called the wave fund? Well, wave, I suppose 218 00:11:59,600 --> 00:12:03,199 Speaker 1: because it follows a wave equation. Shorting's equation is very 219 00:12:03,280 --> 00:12:06,360 Speaker 1: much like equations for other waves that we've seen before, 220 00:12:06,400 --> 00:12:10,200 Speaker 1: that electromagnetism, and it just waves in water. Right, there's 221 00:12:10,200 --> 00:12:13,320 Speaker 1: a certain differential equation which just looks like a wave equation, 222 00:12:13,400 --> 00:12:16,160 Speaker 1: like a wiggle like a like a like a rippling wiggle. Yeah, 223 00:12:16,160 --> 00:12:18,240 Speaker 1: it's like a rippling wiggle, but you know, it's not 224 00:12:18,320 --> 00:12:22,120 Speaker 1: a rippling wiggle in anything physical, right, Like sound waves 225 00:12:22,160 --> 00:12:25,079 Speaker 1: are a wiggle in air, like air pressure. Right yeah, 226 00:12:25,280 --> 00:12:28,480 Speaker 1: light waves are a wiggle in the electromagnetic field, which, 227 00:12:28,760 --> 00:12:30,920 Speaker 1: even if it's hard to imagine, is a physical thing. 228 00:12:31,280 --> 00:12:35,240 Speaker 1: The wave function is complex. It's imaginary values. It's like 229 00:12:35,240 --> 00:12:38,160 Speaker 1: you know, one plus three I and so it's not 230 00:12:38,280 --> 00:12:42,000 Speaker 1: a wiggle in a physical thing itself. So it's it's 231 00:12:42,000 --> 00:12:45,000 Speaker 1: hard to understand because it's like this sort of abstract 232 00:12:45,400 --> 00:12:48,439 Speaker 1: literally complex things in the sense that it exists in 233 00:12:48,480 --> 00:12:51,719 Speaker 1: the imaginary plane, but it controls something real. So I 234 00:12:51,760 --> 00:12:54,240 Speaker 1: wouldn't have called it the wave function, you know, I 235 00:12:54,320 --> 00:12:56,600 Speaker 1: like the word wave, but function to me is sort 236 00:12:56,640 --> 00:13:00,839 Speaker 1: of confusing. Which you have called it the imaginary function? Well, 237 00:13:00,880 --> 00:13:04,680 Speaker 1: I feel like alluding to the imaginary complex plane that 238 00:13:04,720 --> 00:13:07,480 Speaker 1: is not helping me here, I guess, And you just 239 00:13:07,520 --> 00:13:09,720 Speaker 1: brought up maybe a source of confusion, which is that 240 00:13:09,840 --> 00:13:12,160 Speaker 1: you know, you just said the light or a photon 241 00:13:12,400 --> 00:13:16,360 Speaker 1: is like a ripple in the electromagnetic field, right, It's 242 00:13:16,360 --> 00:13:19,320 Speaker 1: a ripple like kind of like a sound waving that 243 00:13:19,400 --> 00:13:22,240 Speaker 1: it's like, it's more intense here in this intense here 244 00:13:22,640 --> 00:13:25,679 Speaker 1: are you saying that? There's also like a photon would 245 00:13:25,720 --> 00:13:30,920 Speaker 1: also have another kind of waving, nous, which is imaginary. Absolutely, 246 00:13:31,200 --> 00:13:34,360 Speaker 1: the photon also has a wave function, right, and that 247 00:13:34,400 --> 00:13:37,640 Speaker 1: wave function determines where the photon is likely to go, 248 00:13:37,920 --> 00:13:41,440 Speaker 1: like which parts of the electromagnetic field are likely to ripple, 249 00:13:41,880 --> 00:13:44,400 Speaker 1: you know, for example, you know, the classical situation is, 250 00:13:44,440 --> 00:13:47,640 Speaker 1: imagine you shoot a photon at two slits in a screen. 251 00:13:48,080 --> 00:13:49,600 Speaker 1: You know which one is it going to go through. 252 00:13:49,679 --> 00:13:51,320 Speaker 1: It has a probability to go through one and a 253 00:13:51,320 --> 00:13:54,239 Speaker 1: probability to go through the other. The wave function controls 254 00:13:54,440 --> 00:13:57,800 Speaker 1: what those probabilities are, right, And if it collapses and 255 00:13:57,800 --> 00:13:59,480 Speaker 1: picks the one on the left, then you get an 256 00:13:59,480 --> 00:14:03,120 Speaker 1: electro magnetic wave through the one on the left. So 257 00:14:03,200 --> 00:14:05,720 Speaker 1: the probability wave and the electromagnetic wave are sort of 258 00:14:05,720 --> 00:14:08,160 Speaker 1: two different things to keep in your mind, and they 259 00:14:08,280 --> 00:14:11,800 Speaker 1: both spread differently. Like why did they call them waves 260 00:14:11,800 --> 00:14:14,880 Speaker 1: in the first place, Like do these like probabilities ripple 261 00:14:14,960 --> 00:14:18,480 Speaker 1: out into space also, or or do they just look 262 00:14:18,520 --> 00:14:21,080 Speaker 1: like a ripple that moves around. They do ripple, and 263 00:14:21,080 --> 00:14:23,440 Speaker 1: they do follow wave mechanics, and that's why they call 264 00:14:23,480 --> 00:14:25,560 Speaker 1: it a wave, and that's why they can do really 265 00:14:25,600 --> 00:14:29,880 Speaker 1: amazing and fascinating things. Because the location of electron is 266 00:14:30,000 --> 00:14:32,960 Speaker 1: controlled by something which is fundamentally a wave, it can 267 00:14:33,000 --> 00:14:36,640 Speaker 1: do things that waves can do. Like it can interfere, Right, 268 00:14:36,680 --> 00:14:40,720 Speaker 1: you can have probabilities interfering with themselves, probably being here 269 00:14:40,840 --> 00:14:44,120 Speaker 1: and there, can interfere with each other and create probabilities 270 00:14:44,160 --> 00:14:47,560 Speaker 1: in other places, just like actual waves can. Right, you 271 00:14:47,640 --> 00:14:49,640 Speaker 1: put two hands in a lake or in a bathtub 272 00:14:49,840 --> 00:14:52,240 Speaker 1: and you make two sources of waves. Those waves can 273 00:14:52,280 --> 00:14:54,640 Speaker 1: interfere with each other, meaning just that they can add 274 00:14:54,720 --> 00:14:56,960 Speaker 1: up or cancel out. So, for example, if I have 275 00:14:57,120 --> 00:15:00,560 Speaker 1: like an electron here, it has like a ripple of 276 00:15:00,680 --> 00:15:04,520 Speaker 1: probability kind of emanating from it, or is that kind 277 00:15:04,520 --> 00:15:07,280 Speaker 1: of static if the electron is static. Well, electrons can't 278 00:15:07,360 --> 00:15:10,520 Speaker 1: actually be totally static, right, because their quantum objects. So 279 00:15:10,560 --> 00:15:13,000 Speaker 1: you can't just like say, electron is here and it's 280 00:15:13,000 --> 00:15:15,760 Speaker 1: not moving. That would violate the Heisenberger in certainty principle, 281 00:15:15,840 --> 00:15:19,080 Speaker 1: would effectively be an electron at absolute zero. But if 282 00:15:19,080 --> 00:15:20,560 Speaker 1: you have an electron, you shoot it out of like 283 00:15:20,600 --> 00:15:23,640 Speaker 1: an electron gun or something, and you want to describe 284 00:15:23,880 --> 00:15:26,240 Speaker 1: what's it likely to do, where is it likely to go? 285 00:15:26,800 --> 00:15:30,160 Speaker 1: Then you have a probability for all those various outcomes, right, 286 00:15:30,160 --> 00:15:32,160 Speaker 1: And the key thing to understand is like, there's not 287 00:15:32,400 --> 00:15:35,480 Speaker 1: a real history that's happening between when you shoot the 288 00:15:35,520 --> 00:15:38,080 Speaker 1: electron and when it hits the wall, and you're just 289 00:15:38,200 --> 00:15:42,840 Speaker 1: learning about it. It's uncertain, right. It has both possibilities 290 00:15:42,960 --> 00:15:47,320 Speaker 1: existing simultaneously until you measure it. And that's the key 291 00:15:47,320 --> 00:15:49,440 Speaker 1: thing that's hard to understand about quantum mechanics is like 292 00:15:49,640 --> 00:15:53,440 Speaker 1: how this measurement changes it from like having two possibilities 293 00:15:53,600 --> 00:15:57,280 Speaker 1: to actually existing in one place, but doesn't exist between 294 00:15:57,320 --> 00:16:00,240 Speaker 1: the places you measure. It only exists where you measure 295 00:16:00,360 --> 00:16:03,160 Speaker 1: in between. They're just probabilities, all right. So you're saying 296 00:16:03,200 --> 00:16:06,320 Speaker 1: that maybe, like an electron is like a little tiny baseball, 297 00:16:06,920 --> 00:16:09,280 Speaker 1: but we just don't know where it is, and where 298 00:16:09,280 --> 00:16:13,080 Speaker 1: it is is determined by this ripple in probability. Yeah, 299 00:16:13,120 --> 00:16:15,240 Speaker 1: I'm saying an electron is like a little tiny baseball, 300 00:16:15,280 --> 00:16:17,560 Speaker 1: but it doesn't have a place where it is. It's 301 00:16:17,600 --> 00:16:20,680 Speaker 1: not like it is someplace and we don't know its 302 00:16:20,720 --> 00:16:23,320 Speaker 1: place is not determined the probability of it being in 303 00:16:23,360 --> 00:16:26,240 Speaker 1: one place or another is determined by the way functions 304 00:16:26,320 --> 00:16:30,440 Speaker 1: like probably to be there seventy one probability be here 305 00:16:30,760 --> 00:16:32,760 Speaker 1: or whatever, so they add up to one. But the 306 00:16:32,760 --> 00:16:35,840 Speaker 1: probabilities are determined by the way function but doesn't actually 307 00:16:35,920 --> 00:16:39,400 Speaker 1: have a location. It just has those probabilities again until 308 00:16:39,440 --> 00:16:41,560 Speaker 1: you measure it, which is the weird bit, and then 309 00:16:41,560 --> 00:16:43,440 Speaker 1: when you measure it then it then it feels like 310 00:16:43,480 --> 00:16:46,240 Speaker 1: you're hit by a baseball. It certainly does. And that's 311 00:16:46,240 --> 00:16:48,720 Speaker 1: why we see these weird quantum effects because these particles 312 00:16:48,960 --> 00:16:51,960 Speaker 1: like electrons can do things that waves can do, like 313 00:16:52,000 --> 00:16:54,080 Speaker 1: if you have two sources of them, you get these 314 00:16:54,120 --> 00:16:57,880 Speaker 1: interference effects, or they can like tunnel through walls. These 315 00:16:57,880 --> 00:17:00,360 Speaker 1: are things that waves can do. Probability waves can do, 316 00:17:00,720 --> 00:17:03,440 Speaker 1: and you get effects because you have these wave like 317 00:17:03,600 --> 00:17:07,639 Speaker 1: properties of the electrons wave function. These probabilities can go 318 00:17:07,760 --> 00:17:10,320 Speaker 1: through walls like the wall doesn't affect it, like it 319 00:17:10,400 --> 00:17:12,199 Speaker 1: just goes through them. The wall does affect that. We 320 00:17:12,200 --> 00:17:16,000 Speaker 1: have a whole fun podcast on quantum tunneling. And it's 321 00:17:16,040 --> 00:17:18,919 Speaker 1: possible to go through walls right because you can have 322 00:17:18,960 --> 00:17:20,720 Speaker 1: a probability to be on one side of the wall 323 00:17:20,880 --> 00:17:22,680 Speaker 1: and then a probability to be on the other side 324 00:17:22,680 --> 00:17:24,720 Speaker 1: of the wall, and you can do that without going 325 00:17:24,880 --> 00:17:28,280 Speaker 1: through the wall. The probability can leak through the wall, 326 00:17:28,560 --> 00:17:30,600 Speaker 1: giving you a chance to be on the other side 327 00:17:30,600 --> 00:17:33,119 Speaker 1: of the wall, even if you're never actually in the wall, 328 00:17:34,160 --> 00:17:36,639 Speaker 1: all right, And so that means that the baseball would 329 00:17:36,640 --> 00:17:38,760 Speaker 1: just appear on the other side, or that that it's 330 00:17:38,760 --> 00:17:40,920 Speaker 1: found a way through the wall. It just appears on 331 00:17:40,960 --> 00:17:44,119 Speaker 1: the other side. Remember that quantum particles don't have to 332 00:17:44,160 --> 00:17:47,000 Speaker 1: have paths between where you've seen them. You see it 333 00:17:47,040 --> 00:17:49,200 Speaker 1: at A and you see it at B doesn't mean 334 00:17:49,200 --> 00:17:52,120 Speaker 1: it went from A to B. Doesn't have like a 335 00:17:52,160 --> 00:17:55,159 Speaker 1: secret history how it got from A to B. It 336 00:17:55,240 --> 00:17:57,520 Speaker 1: was a A and then it was at B. Remember 337 00:17:57,520 --> 00:18:00,560 Speaker 1: they follow fundamentally different rules. It was A, then it 338 00:18:00,640 --> 00:18:03,000 Speaker 1: had lots of probabilities from maybe how it got to 339 00:18:03,040 --> 00:18:05,159 Speaker 1: be not like one of them is true and we 340 00:18:05,240 --> 00:18:08,760 Speaker 1: just don't know it. There are those probabilities. It's undetermined. 341 00:18:08,920 --> 00:18:12,280 Speaker 1: It's not unknown, it's undetermined, and then later it's aid B. 342 00:18:12,680 --> 00:18:14,800 Speaker 1: So it doesn't have to go from A to B 343 00:18:15,040 --> 00:18:16,960 Speaker 1: in order to be at A and then be at B. 344 00:18:17,240 --> 00:18:19,800 Speaker 1: And this is highlighted by the quantum tunneling experiment because 345 00:18:19,840 --> 00:18:22,040 Speaker 1: you can't go from A to B. There's a barrier there. 346 00:18:22,320 --> 00:18:26,360 Speaker 1: All right, Well, let's get into quantum coherence and how 347 00:18:26,400 --> 00:18:29,479 Speaker 1: that relates or how that ties this uncertainty and this 348 00:18:29,520 --> 00:18:33,760 Speaker 1: way function to real things like baseball. But first let's 349 00:18:33,760 --> 00:18:49,240 Speaker 1: take a quick break. All right, we're talking about quantum decoherence, 350 00:18:49,359 --> 00:18:53,400 Speaker 1: and hopefully Daniel will we're not. We're not breaking down 351 00:18:53,400 --> 00:18:57,200 Speaker 1: into de coherence, talking about is. But okay, So particles 352 00:18:57,200 --> 00:19:00,320 Speaker 1: have a way function which tells you it's like a 353 00:19:00,400 --> 00:19:05,160 Speaker 1: ripple in the imaginary space, that tells you the probability 354 00:19:05,320 --> 00:19:08,879 Speaker 1: where that little tiny baseball where you will find it. 355 00:19:09,040 --> 00:19:11,080 Speaker 1: Maybe you weren't to poke in, Yes, exactly right. So 356 00:19:11,119 --> 00:19:14,560 Speaker 1: then what does coherence and decoherence means? So quantum coherence 357 00:19:14,880 --> 00:19:17,919 Speaker 1: is when you have two possible outcomes for what's going 358 00:19:17,960 --> 00:19:21,000 Speaker 1: to happen to your particle, and those possibilities sort of 359 00:19:21,040 --> 00:19:24,600 Speaker 1: line up like the wave functions for those two possibilities 360 00:19:24,880 --> 00:19:28,280 Speaker 1: line up. Now, any solution to the wave equation, any 361 00:19:28,480 --> 00:19:31,080 Speaker 1: like quantum state, you can take it and added to 362 00:19:31,119 --> 00:19:33,480 Speaker 1: another quantum state to get a third quantum state, which 363 00:19:33,520 --> 00:19:35,840 Speaker 1: is a mixture of the two. So you can mix 364 00:19:36,080 --> 00:19:38,520 Speaker 1: two possible wave functions like if you have when it 365 00:19:38,520 --> 00:19:40,879 Speaker 1: says the electron is gonna arrive at point A, and 366 00:19:40,880 --> 00:19:42,760 Speaker 1: you have another one that says the electron's gonna arrive 367 00:19:42,760 --> 00:19:44,919 Speaker 1: at point B. You can have a mixture that like 368 00:19:45,040 --> 00:19:48,400 Speaker 1: mixes A and B with fifty fifty odds. So that's 369 00:19:48,400 --> 00:19:51,720 Speaker 1: a coherent combination. It just says you have two possibilities 370 00:19:51,840 --> 00:19:55,320 Speaker 1: and you've added them together, and they're coherent because their 371 00:19:55,359 --> 00:19:57,600 Speaker 1: wave functions are sort of syncd up. They start in 372 00:19:57,640 --> 00:19:59,920 Speaker 1: the same place and they sort of wiggle in time 373 00:20:00,000 --> 00:20:02,199 Speaker 1: aim together, right, but they don't end up in the 374 00:20:02,240 --> 00:20:05,199 Speaker 1: same place. Isn't there some kind of cancelation or some 375 00:20:05,320 --> 00:20:07,920 Speaker 1: kind of or are you saying coherence is when they 376 00:20:07,920 --> 00:20:10,280 Speaker 1: don't cancel. They can cancel, right. The fact that they 377 00:20:10,280 --> 00:20:13,320 Speaker 1: can cancel is because they are coherent. You only get 378 00:20:13,400 --> 00:20:17,240 Speaker 1: interference effects from coherence sources of waves. Like go back 379 00:20:17,240 --> 00:20:20,320 Speaker 1: to the example of like bathtubs. Right, so you put 380 00:20:20,400 --> 00:20:22,199 Speaker 1: your hand in the water and you slap it, You 381 00:20:22,240 --> 00:20:24,320 Speaker 1: make a rhythm, and you get waves in the water. 382 00:20:24,640 --> 00:20:27,080 Speaker 1: You do the same thing with your other hand if 383 00:20:27,080 --> 00:20:29,280 Speaker 1: you're doing it in the same way, right, if you're 384 00:20:29,320 --> 00:20:32,040 Speaker 1: like slapping the water in time, then you get these 385 00:20:32,040 --> 00:20:35,760 Speaker 1: waves which either add up or cancel out coherently. If 386 00:20:35,800 --> 00:20:37,720 Speaker 1: your second hand instead it's just like a random just 387 00:20:37,760 --> 00:20:39,960 Speaker 1: like randomly slapping it, then they're not going to add 388 00:20:40,040 --> 00:20:41,880 Speaker 1: up nicely. It's just going to be a big emotion. 389 00:20:41,880 --> 00:20:44,560 Speaker 1: It's going to spread out to nothing. So you only 390 00:20:44,600 --> 00:20:48,439 Speaker 1: get these interference effects when the quantum waves are in sync. 391 00:20:48,720 --> 00:20:52,199 Speaker 1: That's quantum coherence, and that's what allows quantum things to 392 00:20:52,200 --> 00:20:56,119 Speaker 1: be sort of quantumy, meaning that they're in sync in time. 393 00:20:56,440 --> 00:20:58,600 Speaker 1: So what you're saying or in time and space, Yeah, 394 00:20:58,640 --> 00:21:01,760 Speaker 1: they're in sync in time, and so at every point 395 00:21:01,880 --> 00:21:05,399 Speaker 1: in space they can interfere. At one point in space, 396 00:21:05,400 --> 00:21:09,080 Speaker 1: you might get cancelation because they're waving in opposite directions, 397 00:21:09,560 --> 00:21:12,400 Speaker 1: and at another point in space they might support each 398 00:21:12,400 --> 00:21:15,280 Speaker 1: other because they're waving in the same direction. But they 399 00:21:15,320 --> 00:21:18,919 Speaker 1: can only do that consistently if they're in sync in time. 400 00:21:19,080 --> 00:21:22,080 Speaker 1: So it sounds like, you know, particles have these wave 401 00:21:22,119 --> 00:21:25,280 Speaker 1: functions and they someone have to sync up in order 402 00:21:25,320 --> 00:21:27,399 Speaker 1: for them to interact with each other, because if they 403 00:21:27,400 --> 00:21:30,199 Speaker 1: don't sink up, then then what happens They just cancel 404 00:21:30,280 --> 00:21:33,159 Speaker 1: each other out or they can interact, or what happens 405 00:21:33,160 --> 00:21:35,080 Speaker 1: if they don't sink up. If they don't sink up, 406 00:21:35,280 --> 00:21:37,920 Speaker 1: then you don't get any of these interference effects. It's 407 00:21:37,960 --> 00:21:41,720 Speaker 1: like if your noise cancelation headphones, right, if those were 408 00:21:41,760 --> 00:21:44,560 Speaker 1: sort of just like randomly putting out sounds instead of 409 00:21:44,760 --> 00:21:47,200 Speaker 1: like sinking up to the sounds that are coming at 410 00:21:47,240 --> 00:21:50,800 Speaker 1: your ear and producing exactly the opposite sound to cancel 411 00:21:50,840 --> 00:21:54,320 Speaker 1: them out. Right, your noise canceling headphones only work because 412 00:21:54,320 --> 00:21:58,960 Speaker 1: they produce a coherent noise which cancels out the ambient noise. Otherwise, 413 00:21:59,280 --> 00:22:01,800 Speaker 1: if they put out just random, arbitrary noise, they wouldn't 414 00:22:01,800 --> 00:22:03,679 Speaker 1: cancel each other out, and you just get sort of 415 00:22:03,720 --> 00:22:06,159 Speaker 1: normal stuff you can have like A and B. You 416 00:22:06,160 --> 00:22:09,679 Speaker 1: wouldn't have like weird interference effects between the incoming noise 417 00:22:09,680 --> 00:22:12,199 Speaker 1: and the noise produced by the headphones, and all the 418 00:22:12,280 --> 00:22:16,240 Speaker 1: weird quantumness comes from those like interference effects, these effects 419 00:22:16,240 --> 00:22:19,760 Speaker 1: of the probability wave. And if you don't have coherence, 420 00:22:19,920 --> 00:22:22,719 Speaker 1: then you don't get those effects. Okay, so you need 421 00:22:22,800 --> 00:22:27,160 Speaker 1: coherence in order to have interference, just a little maybe 422 00:22:27,200 --> 00:22:29,960 Speaker 1: counter in Twitter. But it's not a frequency thing, right, 423 00:22:30,080 --> 00:22:31,919 Speaker 1: It's not like they have to be the same frequency 424 00:22:32,160 --> 00:22:35,399 Speaker 1: or fit the same number of wavelengths within the same space. 425 00:22:35,520 --> 00:22:37,399 Speaker 1: It's something a little bit more than that. It's more 426 00:22:37,400 --> 00:22:39,119 Speaker 1: than that they have to be linked up. They have 427 00:22:39,160 --> 00:22:41,879 Speaker 1: to like sync up in time. Otherwise you could have 428 00:22:42,000 --> 00:22:44,840 Speaker 1: like coherence just for a moment, right, but to sink 429 00:22:44,920 --> 00:22:47,400 Speaker 1: up in time to be like consistently giving up these 430 00:22:47,400 --> 00:22:50,040 Speaker 1: probability waves that interfere, then they have to be sort 431 00:22:50,040 --> 00:22:52,199 Speaker 1: of syncd up, which is linked in time that to 432 00:22:52,240 --> 00:22:54,399 Speaker 1: like start at the same place and go down the 433 00:22:54,440 --> 00:22:56,679 Speaker 1: same time or up at the same time. Either way, 434 00:22:56,720 --> 00:22:59,440 Speaker 1: they have to like match each other in phase, right, 435 00:22:59,480 --> 00:23:02,480 Speaker 1: But they can so cancel each other out and be coherent, right, 436 00:23:02,680 --> 00:23:06,240 Speaker 1: Like you can be coherent and destructive at the same time. 437 00:23:06,560 --> 00:23:09,520 Speaker 1: It's different than decoherent, just like noise canceling headphones. Right. 438 00:23:09,720 --> 00:23:11,840 Speaker 1: The cool thing about the quantum wave function is that 439 00:23:11,880 --> 00:23:15,479 Speaker 1: we actually have a lot of intuition for how waves work. Right, 440 00:23:15,560 --> 00:23:19,240 Speaker 1: All these effects, interference and cancelation, these are normal things. 441 00:23:19,280 --> 00:23:22,400 Speaker 1: It's just weird when you apply it to the probability 442 00:23:22,520 --> 00:23:25,680 Speaker 1: for something to happen. So we're very familiar and happy 443 00:23:25,720 --> 00:23:27,840 Speaker 1: to talk about waves and that none of that is weird, 444 00:23:27,920 --> 00:23:30,720 Speaker 1: Like noise canceling headphones are not quantum magic. It's just 445 00:23:30,800 --> 00:23:33,800 Speaker 1: weird when you apply to the probability for an experiment 446 00:23:33,840 --> 00:23:37,800 Speaker 1: to have a certain outcome. Right, And lasers are also coherent, right, Like, 447 00:23:37,920 --> 00:23:40,040 Speaker 1: that's kind of what a laser is, Yes, exactly, a 448 00:23:40,119 --> 00:23:42,400 Speaker 1: laser is a coherent source of light. All the photons 449 00:23:42,400 --> 00:23:44,840 Speaker 1: are like in phase and have the same frequency, so 450 00:23:44,880 --> 00:23:47,720 Speaker 1: they add up together. Right, So it's a very intense 451 00:23:47,840 --> 00:23:51,240 Speaker 1: source of coherent lights. Okay, So that's at the microscopic level, 452 00:23:51,480 --> 00:23:55,600 Speaker 1: like electrons and photons and quirks. They can have this coherence. 453 00:23:55,800 --> 00:23:58,720 Speaker 1: But then something happens when you go up to the 454 00:23:58,840 --> 00:24:01,280 Speaker 1: bigger things, like when we have to worry about coherence 455 00:24:01,280 --> 00:24:02,920 Speaker 1: at the baseball level. Right, Well, we don't have to 456 00:24:02,920 --> 00:24:07,680 Speaker 1: worry about interference of baseballs because they're not coherent quantum objects, 457 00:24:07,720 --> 00:24:10,879 Speaker 1: like all of their particles are not wiggling in phase. 458 00:24:10,960 --> 00:24:14,359 Speaker 1: They're all scrambled and random. It's like a huge choir 459 00:24:14,359 --> 00:24:16,919 Speaker 1: of children all singing different songs at different volumes and 460 00:24:16,920 --> 00:24:19,240 Speaker 1: different speeds. And so what we see is like a 461 00:24:19,359 --> 00:24:22,080 Speaker 1: big average gamush. We don't see any sort of like 462 00:24:22,119 --> 00:24:25,480 Speaker 1: interference effects when two baseballs bounce off each other because 463 00:24:25,520 --> 00:24:29,080 Speaker 1: they don't have coherent quantum waves, their faces are all scrambled. 464 00:24:29,119 --> 00:24:31,439 Speaker 1: All right, Well, let's talk about that scrambling, because I 465 00:24:31,440 --> 00:24:35,280 Speaker 1: think maybe that's the key of what makes things quantumy 466 00:24:35,400 --> 00:24:37,760 Speaker 1: or not, Like maybe step us through, Like, okay, we 467 00:24:37,800 --> 00:24:42,240 Speaker 1: start with one atom, and the particles inside the atom 468 00:24:42,680 --> 00:24:45,840 Speaker 1: do have this wave function, and presimably they're coherent. Like 469 00:24:45,920 --> 00:24:48,600 Speaker 1: are the protons and neutrons and quarks inside of an 470 00:24:48,600 --> 00:24:51,760 Speaker 1: atom coherent together? Or is there already some kind of 471 00:24:51,880 --> 00:24:55,200 Speaker 1: smushing at that level? They can be coherent. Absolutely. There's 472 00:24:55,200 --> 00:24:57,800 Speaker 1: no limit to how large a coherent system can be. 473 00:24:57,840 --> 00:25:00,520 Speaker 1: It just gets harder and harder to do because it 474 00:25:00,560 --> 00:25:03,399 Speaker 1: has to be isolated. The key is that anytime you 475 00:25:03,440 --> 00:25:06,159 Speaker 1: interact with something, then it becomes part of your system, 476 00:25:06,400 --> 00:25:09,000 Speaker 1: and so the system sort of grows and grows and grows, 477 00:25:09,040 --> 00:25:11,240 Speaker 1: so it's easier to start from like like a single particle. 478 00:25:11,320 --> 00:25:14,600 Speaker 1: Take a single electron or a single photon, right, it 479 00:25:14,760 --> 00:25:17,199 Speaker 1: has a certain way of function, and that way function 480 00:25:17,280 --> 00:25:20,080 Speaker 1: is coherent, has like two possibilities for what it can do, 481 00:25:20,320 --> 00:25:22,840 Speaker 1: and those possibilities are coherent, and so you get like 482 00:25:23,000 --> 00:25:26,880 Speaker 1: interesting interference effects. That's why, for example, a single photon 483 00:25:27,280 --> 00:25:31,400 Speaker 1: going through the famous double slid experiment can interfere with itself. Right, 484 00:25:31,720 --> 00:25:35,600 Speaker 1: It's two possibilities are interfering. So single photon with two 485 00:25:35,600 --> 00:25:39,800 Speaker 1: coherent possibilities can interfere with itself. Now things get messy 486 00:25:40,119 --> 00:25:43,160 Speaker 1: once that photon starts to interact with other stuff because 487 00:25:43,200 --> 00:25:46,399 Speaker 1: now the two possibilities for the photon interact differently with 488 00:25:46,440 --> 00:25:48,960 Speaker 1: the environment. You know this interact with the wall or 489 00:25:49,000 --> 00:25:51,760 Speaker 1: interact with the tool whatever you're using to measure it, 490 00:25:52,040 --> 00:25:55,160 Speaker 1: and they change the phases of those two different outcomes, 491 00:25:55,240 --> 00:25:58,520 Speaker 1: and now it's decoherent. So a particle can be coherent. 492 00:25:58,520 --> 00:26:00,800 Speaker 1: You can even have two particles coher but once you 493 00:26:00,840 --> 00:26:03,160 Speaker 1: touch it, once you interact with it, then you can 494 00:26:03,200 --> 00:26:05,720 Speaker 1: break that coherence. Right. But you know we're trying to 495 00:26:05,760 --> 00:26:08,719 Speaker 1: build up from like particles up to a baseball. And 496 00:26:08,800 --> 00:26:12,639 Speaker 1: so like if I assemble you know, three quarts together 497 00:26:12,680 --> 00:26:16,080 Speaker 1: into a proton, are they still coherent together or do 498 00:26:16,160 --> 00:26:18,600 Speaker 1: they start to kind of get out of sink? Once 499 00:26:18,600 --> 00:26:20,840 Speaker 1: I put them together into a proton, they can be 500 00:26:20,920 --> 00:26:23,439 Speaker 1: coherent together. And you can have a single wave function 501 00:26:23,480 --> 00:26:25,960 Speaker 1: that describes just those particles. And if you want to 502 00:26:26,000 --> 00:26:28,480 Speaker 1: have a wave function that describes just those particles, it 503 00:26:28,600 --> 00:26:31,320 Speaker 1: can't be interacting with anything else, because then you'd have 504 00:26:31,400 --> 00:26:33,600 Speaker 1: to include that in the wave function. If you want 505 00:26:33,600 --> 00:26:35,399 Speaker 1: to have a wave function for just your atom, you 506 00:26:35,400 --> 00:26:38,399 Speaker 1: have to keep it isolated, right, And that gets harder 507 00:26:38,440 --> 00:26:41,080 Speaker 1: and harder to do as things get bigger. Like it's 508 00:26:41,119 --> 00:26:44,800 Speaker 1: possible to imagine a photon in an experiment that doesn't 509 00:26:44,840 --> 00:26:47,679 Speaker 1: interact with anything you've built a special trap or whatever. 510 00:26:48,200 --> 00:26:51,719 Speaker 1: It's harder to imagine a baseball that doesn't interact with anything. 511 00:26:51,840 --> 00:26:55,200 Speaker 1: No air, molecules, no photons, know nothing. There's so many 512 00:26:55,280 --> 00:26:57,960 Speaker 1: particles in there, it becomes harder and harder to keep 513 00:26:58,000 --> 00:27:02,120 Speaker 1: it isolated. That's why decoherence appears as soon as things 514 00:27:02,160 --> 00:27:05,119 Speaker 1: get big, because it's really hard to keep larger, realistic 515 00:27:05,160 --> 00:27:09,200 Speaker 1: size things isolated and coherent. Right, I guess I'm trying 516 00:27:09,240 --> 00:27:12,159 Speaker 1: to understand when that comes in. So, like, if I 517 00:27:12,280 --> 00:27:15,359 Speaker 1: build a nucleus side of protons that are all in 518 00:27:15,440 --> 00:27:19,159 Speaker 1: sync inside, then are they all also together in sync? 519 00:27:19,240 --> 00:27:21,440 Speaker 1: Like you know, like carbon has twelve of them in 520 00:27:21,480 --> 00:27:24,280 Speaker 1: the nucleus and they're all content there together, held by 521 00:27:24,280 --> 00:27:27,440 Speaker 1: the strong nuclear force. Are they still coherent or are 522 00:27:27,440 --> 00:27:29,520 Speaker 1: they starting to kind of fuzz out? If you keep 523 00:27:29,520 --> 00:27:32,440 Speaker 1: it isolated, it can stay coherent absolutely. Okay, So then 524 00:27:32,640 --> 00:27:34,919 Speaker 1: I build an atom, I throw in some electrons, and 525 00:27:34,960 --> 00:27:37,960 Speaker 1: that also gets syncd up. And at what point do 526 00:27:38,080 --> 00:27:40,760 Speaker 1: things start to kind of go awry? At the point 527 00:27:40,800 --> 00:27:43,719 Speaker 1: where it becomes impossible to keep it isolated from the 528 00:27:43,720 --> 00:27:45,760 Speaker 1: rest of the universe. But then couldn't I be in 529 00:27:45,760 --> 00:27:49,080 Speaker 1: sync with the rest of the universe Daniel, Yes, exactly. 530 00:27:49,200 --> 00:27:51,760 Speaker 1: Some people think that there is a wave function for 531 00:27:51,800 --> 00:27:54,840 Speaker 1: the whole universe, right. The problem is that now we're 532 00:27:54,880 --> 00:27:57,640 Speaker 1: inside the wave function. Now the way function includes us, 533 00:27:58,200 --> 00:28:00,600 Speaker 1: and so it's hard to see these quantum effects now 534 00:28:00,640 --> 00:28:03,199 Speaker 1: because we are part of the experiment. All right, So 535 00:28:03,240 --> 00:28:06,240 Speaker 1: I got an atom and it's coherent and it's syncd up, 536 00:28:06,400 --> 00:28:08,960 Speaker 1: and now I add another atom. Is that a problem 537 00:28:09,119 --> 00:28:11,760 Speaker 1: or does it just get bigger. It's not a problem. 538 00:28:11,840 --> 00:28:14,240 Speaker 1: It gets bigger. It's just harder to keep a coherent 539 00:28:14,280 --> 00:28:16,640 Speaker 1: because you have to keep it isolated from the system. 540 00:28:16,800 --> 00:28:20,720 Speaker 1: Remember one time we talked about building macroscopic like big 541 00:28:20,760 --> 00:28:24,240 Speaker 1: stize stuff that behaves in a quantum mechanical way. This 542 00:28:24,280 --> 00:28:27,840 Speaker 1: has done in a special way using Bose. Einstein condensates 543 00:28:28,119 --> 00:28:31,000 Speaker 1: special form of matter that can be coherent that can 544 00:28:31,040 --> 00:28:33,720 Speaker 1: stay together and you can stay isolated from the rest 545 00:28:33,720 --> 00:28:36,199 Speaker 1: of the system. These things don't last very long. They 546 00:28:36,280 --> 00:28:38,720 Speaker 1: last like, you know, seconds or minutes because it's hard 547 00:28:38,760 --> 00:28:42,440 Speaker 1: to keep them isolated. So it's like real experimental bravado 548 00:28:42,480 --> 00:28:44,959 Speaker 1: if you can put more than a few atoms together 549 00:28:45,440 --> 00:28:49,040 Speaker 1: in a quantum coherent system and keep them coherent, keep 550 00:28:49,080 --> 00:28:51,760 Speaker 1: them from interacting with the rest of the universe and 551 00:28:51,760 --> 00:28:54,160 Speaker 1: getting their way functions sort of muddled up with the 552 00:28:54,200 --> 00:28:56,280 Speaker 1: rest of the universe. Yeah, well, I guess maybe a 553 00:28:56,280 --> 00:28:58,600 Speaker 1: big part of it seems to be this idea of 554 00:28:58,600 --> 00:29:01,560 Speaker 1: an experiment and like who's in on the know and 555 00:29:01,600 --> 00:29:04,120 Speaker 1: who's outside of the experiment, and what does it mean 556 00:29:04,160 --> 00:29:07,320 Speaker 1: for something to be kind of pristine or not pristine? 557 00:29:07,520 --> 00:29:09,480 Speaker 1: So maybe let's get a little bit into that, which 558 00:29:09,520 --> 00:29:12,560 Speaker 1: is I think basically the idea of decoherence. Right, all right, 559 00:29:12,600 --> 00:29:15,240 Speaker 1: let's get into that, but first let's take another quick break. 560 00:29:27,160 --> 00:29:30,320 Speaker 1: All right, we're talking about quantum decoherence, which is kind 561 00:29:30,320 --> 00:29:33,000 Speaker 1: of at the heart of this kind of headache that 562 00:29:33,040 --> 00:29:37,440 Speaker 1: people have about quantum mechanics and trying to understand it 563 00:29:37,480 --> 00:29:41,400 Speaker 1: at an intuitive level. So, you know, small particles can 564 00:29:41,480 --> 00:29:46,880 Speaker 1: have quantum effects and wave functions and weird probability existences. 565 00:29:47,320 --> 00:29:50,640 Speaker 1: But once you start piling them on together, it gets 566 00:29:50,680 --> 00:29:55,760 Speaker 1: harder to kind of keep pristine I guess, right, untouched 567 00:29:55,800 --> 00:29:59,000 Speaker 1: from to an observer from the outside or just to 568 00:29:59,080 --> 00:30:02,320 Speaker 1: the universe into the same because the universe, i imagine, 569 00:30:02,360 --> 00:30:05,000 Speaker 1: doesn't care, right, like the universe if there is a 570 00:30:05,040 --> 00:30:08,400 Speaker 1: quantum way function for the entire universe, like, it doesn't care, 571 00:30:08,880 --> 00:30:11,840 Speaker 1: Like it doesn't know the difference between something that you 572 00:30:11,840 --> 00:30:14,720 Speaker 1: you would think is inquirent or not. Yeah, that's right. 573 00:30:14,800 --> 00:30:16,920 Speaker 1: And the tricky thing here is that we want to 574 00:30:16,960 --> 00:30:19,480 Speaker 1: have a wave function just for our experiment because we 575 00:30:19,560 --> 00:30:22,880 Speaker 1: want to see quantum effects. If we become part of 576 00:30:22,920 --> 00:30:25,880 Speaker 1: the experiment, then we no longer see the quantum effects 577 00:30:25,880 --> 00:30:28,480 Speaker 1: because we only are like on one branch of that history. 578 00:30:28,600 --> 00:30:30,200 Speaker 1: What do you mean we don't see the effects like 579 00:30:30,240 --> 00:30:32,600 Speaker 1: we are also existing in multiple plays at the same 580 00:30:32,640 --> 00:30:36,240 Speaker 1: time to somebody outside of our universe. Somebody outside of 581 00:30:36,240 --> 00:30:38,960 Speaker 1: our universe sees a wave function for the whole universe, 582 00:30:38,960 --> 00:30:42,040 Speaker 1: and they see lots of different possible outcomes, right, and 583 00:30:42,080 --> 00:30:45,080 Speaker 1: those things can exist simultaneously until like if they observe 584 00:30:45,160 --> 00:30:48,040 Speaker 1: the universe. But we're on just sort of one branch 585 00:30:48,160 --> 00:30:50,800 Speaker 1: of that history the way we are existing, and so 586 00:30:50,880 --> 00:30:54,040 Speaker 1: we don't see those other branches necessarily. And so if 587 00:30:54,040 --> 00:30:55,720 Speaker 1: you want to see a quantum effect, you have to 588 00:30:55,760 --> 00:30:59,800 Speaker 1: be like outside of that quantum system and take some 589 00:31:00,000 --> 00:31:02,440 Speaker 1: measurements of it. Right now, as soon as you take 590 00:31:02,440 --> 00:31:05,200 Speaker 1: those measurements of it, you've sort of inserted yourself in 591 00:31:05,280 --> 00:31:08,720 Speaker 1: that quantum system and it becomes much muddier. I think 592 00:31:08,720 --> 00:31:11,040 Speaker 1: you just blew my mind here, because like, if we 593 00:31:11,160 --> 00:31:14,320 Speaker 1: are all part of the quantum function of the universe, 594 00:31:14,640 --> 00:31:18,400 Speaker 1: that means that there are like multiples of me out 595 00:31:18,440 --> 00:31:22,520 Speaker 1: there to some alien observer outside of the universe. Like 596 00:31:22,560 --> 00:31:25,320 Speaker 1: I I only think that I exist as one person 597 00:31:26,160 --> 00:31:31,840 Speaker 1: because what because I am observing myself? I guess. Yeah, 598 00:31:31,880 --> 00:31:34,200 Speaker 1: it's complicated. And this whole question of like who is 599 00:31:34,200 --> 00:31:37,120 Speaker 1: an observer? Who can collapse the wave function? When does 600 00:31:37,160 --> 00:31:39,880 Speaker 1: the wave function get collapsed? It's very complicated. It's a 601 00:31:39,880 --> 00:31:43,280 Speaker 1: whole other philosophical question that it hasn't been resolved. We 602 00:31:43,320 --> 00:31:45,360 Speaker 1: don't know the answer to it. It's like the biggest 603 00:31:45,360 --> 00:31:48,120 Speaker 1: problem in the foundations of quantum mechanics. We're not going 604 00:31:48,160 --> 00:31:50,600 Speaker 1: to figure it out today on the podcast, but it 605 00:31:50,800 --> 00:31:54,040 Speaker 1: is connected to this question of quantum decoherence and quantum 606 00:31:54,080 --> 00:31:58,120 Speaker 1: coherence because we're interested in observing quantum effects, like when 607 00:31:58,120 --> 00:32:01,560 Speaker 1: do things look quantumy and when do the not look quantity, 608 00:32:02,160 --> 00:32:06,000 Speaker 1: and if you are inside the experiment, things don't look quantity. 609 00:32:06,080 --> 00:32:08,000 Speaker 1: Like I've never talked to a photon. I don't know 610 00:32:08,040 --> 00:32:10,040 Speaker 1: what it's like to be a photon in a double 611 00:32:10,040 --> 00:32:13,320 Speaker 1: slit experiment that has experienced one path does it experienced 612 00:32:13,400 --> 00:32:15,840 Speaker 1: some weird combination of multiple paths? But I know what 613 00:32:15,880 --> 00:32:18,680 Speaker 1: it's like to be me, and I don't experience superpositions, right, 614 00:32:18,920 --> 00:32:21,480 Speaker 1: I don't live two lives at the same time. Sometimes 615 00:32:21,480 --> 00:32:23,440 Speaker 1: it feels like it. Yeah, okay, so it kind of 616 00:32:23,480 --> 00:32:26,480 Speaker 1: depends on who you're who you ask whether something feels 617 00:32:26,520 --> 00:32:29,200 Speaker 1: quantity or not. Like, you know, we can have a 618 00:32:29,240 --> 00:32:32,280 Speaker 1: little experiment here in front of us and looks and 619 00:32:32,440 --> 00:32:36,200 Speaker 1: feels quantity, but to the particles inside it doesn't feel quantity, 620 00:32:36,360 --> 00:32:38,920 Speaker 1: or to an observer outside of our universe, we feel 621 00:32:39,000 --> 00:32:41,440 Speaker 1: quantumy to them, oh absolutely, Like there's a very simple 622 00:32:41,440 --> 00:32:44,120 Speaker 1: thought experiment to think about that. Say I set up 623 00:32:44,160 --> 00:32:46,800 Speaker 1: a quantum experiment that can have you know, two outcomes 624 00:32:46,800 --> 00:32:49,680 Speaker 1: A or B, and I run the experiment. Now before 625 00:32:49,720 --> 00:32:51,560 Speaker 1: I read the outcome of the experiment, you could say, 626 00:32:51,640 --> 00:32:54,760 Speaker 1: there's two possibilities A or B. Cool. What if you're 627 00:32:54,840 --> 00:32:58,480 Speaker 1: running experiment and your experiment is me running that experiment. 628 00:32:58,640 --> 00:33:01,200 Speaker 1: So you put me in a box and I do 629 00:33:01,320 --> 00:33:03,640 Speaker 1: the experiment, and I know the outcome, but you don't 630 00:33:03,720 --> 00:33:07,720 Speaker 1: yet know the outcome, right, So I am your experiment. 631 00:33:08,040 --> 00:33:10,560 Speaker 1: Well you know, am I living in the outcomes of 632 00:33:10,600 --> 00:33:13,640 Speaker 1: both experiments until you ask me what's the outcome of 633 00:33:13,680 --> 00:33:17,680 Speaker 1: my experiment? Right? So absolutely, Like the quantumminess depends on 634 00:33:17,840 --> 00:33:20,760 Speaker 1: who's doing the asking and who's doing the observing and 635 00:33:21,000 --> 00:33:23,320 Speaker 1: who has collapsed the wave function. And that's like that 636 00:33:23,440 --> 00:33:26,000 Speaker 1: deep question of quantum mechanics that we don't know the 637 00:33:26,000 --> 00:33:28,880 Speaker 1: answer to, is like when do wave functions get collapsed 638 00:33:28,880 --> 00:33:30,920 Speaker 1: and how did they get collapsed? Right? Like if the 639 00:33:30,960 --> 00:33:35,040 Speaker 1: cat ensured the Inger's box was a physicist, like, the 640 00:33:35,080 --> 00:33:38,480 Speaker 1: cat knows whether or not it's dead or alive, or 641 00:33:38,560 --> 00:33:41,920 Speaker 1: you know, the radioactive particle click or not. But to 642 00:33:42,080 --> 00:33:44,320 Speaker 1: us the cat is dead analyzed, but to the cat 643 00:33:44,360 --> 00:33:46,480 Speaker 1: it's not. That's right. And so that's why I say 644 00:33:46,640 --> 00:33:50,080 Speaker 1: you can observe quantum effects if you're outside the experiment, 645 00:33:50,120 --> 00:33:52,240 Speaker 1: Like you observe a quantum effect on me because I'm 646 00:33:52,280 --> 00:33:55,000 Speaker 1: part of your experiment. I observe a quantum effect on 647 00:33:55,120 --> 00:33:58,040 Speaker 1: the little experiment that I'm running with the cat or whatever, Right, 648 00:33:58,200 --> 00:34:02,240 Speaker 1: I don't experience the quantum effect that you observe in me. Right, 649 00:34:02,280 --> 00:34:04,400 Speaker 1: So then how does that apply to our baseball? Like 650 00:34:04,560 --> 00:34:06,520 Speaker 1: is it? I think kind of like as you pile 651 00:34:06,640 --> 00:34:11,279 Speaker 1: on more particles that are interacting with more things, you're 652 00:34:11,320 --> 00:34:14,680 Speaker 1: sort of opening up those throwed a group boxes. Yeah, exactly. 653 00:34:14,680 --> 00:34:16,440 Speaker 1: There's two ways to think about it, sort of one 654 00:34:16,520 --> 00:34:19,520 Speaker 1: is intuitive and the other is mathematical. The intuitive way 655 00:34:19,680 --> 00:34:22,440 Speaker 1: is that as the baseball starts to interact with more stuff, 656 00:34:22,640 --> 00:34:26,439 Speaker 1: that stuff becomes part of the baseball's quantum wave function, right, 657 00:34:26,480 --> 00:34:28,479 Speaker 1: Like now you have a wave function for the bat 658 00:34:28,600 --> 00:34:31,400 Speaker 1: and the baseball together, and so the bat can no 659 00:34:31,480 --> 00:34:34,640 Speaker 1: longer do like quantum experiments on the baseball because it's 660 00:34:34,640 --> 00:34:37,520 Speaker 1: like entangled with the baseball the same way that like 661 00:34:37,560 --> 00:34:40,960 Speaker 1: I'm inside your experiment, And so the intuitive ways, like, 662 00:34:41,280 --> 00:34:44,319 Speaker 1: as a particle starts to interact with the system around it, 663 00:34:44,520 --> 00:34:47,000 Speaker 1: it gets sort of enmeshed quantum mechanically with the wave 664 00:34:47,040 --> 00:34:49,680 Speaker 1: function of the larger system. So that system is now 665 00:34:50,200 --> 00:34:54,600 Speaker 1: part of that you know, particle or baseball's quantum wave function, 666 00:34:54,800 --> 00:34:57,000 Speaker 1: and it can no longer see the quantum effects of 667 00:34:57,040 --> 00:35:01,040 Speaker 1: those things. That's decoherence. And so the mathematical way to 668 00:35:01,040 --> 00:35:04,280 Speaker 1: think about it is that when a particle interacts with something, 669 00:35:04,280 --> 00:35:07,160 Speaker 1: what happens is that its phase gets shifted a little bit, 670 00:35:07,480 --> 00:35:11,080 Speaker 1: and the phases of the different possibilities get shifted differently 671 00:35:11,120 --> 00:35:14,200 Speaker 1: based on how you're interacting. And so what happens is 672 00:35:14,239 --> 00:35:17,000 Speaker 1: that all the phases of the baseball when it hits 673 00:35:17,000 --> 00:35:19,359 Speaker 1: the bat gets shifted a tiny little bit and they 674 00:35:19,360 --> 00:35:21,880 Speaker 1: all get scrambled. And so now the phases are like 675 00:35:21,960 --> 00:35:24,760 Speaker 1: out of sync and they can't do quantum stuff together 676 00:35:25,000 --> 00:35:28,680 Speaker 1: because they have deco here because they're all like random phases. Wait, 677 00:35:28,719 --> 00:35:31,360 Speaker 1: so you know I was building this baseball from atoms, 678 00:35:31,920 --> 00:35:35,480 Speaker 1: and so it isn't impossible to build a baseball that 679 00:35:35,640 --> 00:35:39,160 Speaker 1: is still coherent, like all of the wave functions inside 680 00:35:39,160 --> 00:35:43,200 Speaker 1: are in sync and happy and quantumy, in which case 681 00:35:43,360 --> 00:35:47,040 Speaker 1: the whole baseball is quantumy. Theoretically possible, practically very very 682 00:35:47,080 --> 00:35:49,520 Speaker 1: difficult because you have to isolate it from the entire 683 00:35:49,600 --> 00:35:53,120 Speaker 1: university nobody could interact with or observe that baseball. Right, 684 00:35:53,160 --> 00:35:55,400 Speaker 1: Let's say I put it inside of a short finger's box. 685 00:35:55,680 --> 00:35:59,640 Speaker 1: It's there, it's not interacting. That baseball is quantumy. That 686 00:35:59,680 --> 00:36:02,520 Speaker 1: baseball is quantumy. Now, like, practically shortening this box is 687 00:36:02,520 --> 00:36:05,760 Speaker 1: impossible because you know, no box is impervious to heat 688 00:36:05,840 --> 00:36:08,880 Speaker 1: and all sorts of other interactions. But let's say theoretically 689 00:36:08,920 --> 00:36:12,000 Speaker 1: you've built some way to isolate the baseball completely. Then yes, 690 00:36:12,080 --> 00:36:15,600 Speaker 1: it is still quantumy. It has not interacted with anything else. Right, 691 00:36:15,600 --> 00:36:18,040 Speaker 1: But I think maybe a key limitation here is that 692 00:36:18,200 --> 00:36:20,520 Speaker 1: it's not that the baseball can be here or in mars. 693 00:36:21,400 --> 00:36:25,080 Speaker 1: The probability of where it is isn't that big, because 694 00:36:25,600 --> 00:36:29,359 Speaker 1: you know, you're just adding tiny little probabilities, right, Like 695 00:36:29,560 --> 00:36:32,600 Speaker 1: it can't be here or a meter away. That quantum 696 00:36:32,600 --> 00:36:35,680 Speaker 1: meanness of the isolated baseball is like it's here or 697 00:36:35,760 --> 00:36:37,960 Speaker 1: it's a few angst from to the right. It could 698 00:36:38,000 --> 00:36:41,640 Speaker 1: actually have quite different possible locations. It depends on how 699 00:36:41,680 --> 00:36:43,520 Speaker 1: you set it up inside the box. It could be 700 00:36:43,560 --> 00:36:46,400 Speaker 1: sensitive to one quantum fluctuation which sends it in one 701 00:36:46,440 --> 00:36:49,240 Speaker 1: direction or the other direction. I think what you're referring 702 00:36:49,280 --> 00:36:51,440 Speaker 1: to though, is more like the classical sense of the 703 00:36:51,480 --> 00:36:55,000 Speaker 1: decohered baseball. Baseball that's like that you're familiar with is 704 00:36:55,000 --> 00:36:57,239 Speaker 1: flying through the air in a normal baseball game. We 705 00:36:57,280 --> 00:37:00,560 Speaker 1: don't see those quantum effects because they all are bridge out, 706 00:37:00,920 --> 00:37:03,799 Speaker 1: because all the quantum effects of all those particles in 707 00:37:03,840 --> 00:37:06,120 Speaker 1: the baseball are not pulling like in the same directions. 708 00:37:06,160 --> 00:37:10,040 Speaker 1: You never see like weird interference effects or weird probability 709 00:37:10,040 --> 00:37:13,520 Speaker 1: distributions because they've all averaged out. They're all decoherent. If 710 00:37:13,560 --> 00:37:16,440 Speaker 1: they were coherent, then yes, the baseball could do quantum 711 00:37:16,480 --> 00:37:19,600 Speaker 1: things the way like Schruninger's cat can do quantum things 712 00:37:19,680 --> 00:37:22,920 Speaker 1: like be dead or alive. Have those possibilities at the 713 00:37:22,960 --> 00:37:25,640 Speaker 1: same time. Okay, so now you're saying that, like, if 714 00:37:25,760 --> 00:37:28,759 Speaker 1: I has this baseball on the box and I open it, 715 00:37:29,120 --> 00:37:31,480 Speaker 1: that's the same thing as hitting it with a bat, Yes, 716 00:37:32,080 --> 00:37:34,359 Speaker 1: because now photons are hitting it and you are seeing 717 00:37:34,400 --> 00:37:36,920 Speaker 1: those photons, and like the bat is connected to a batter, 718 00:37:37,040 --> 00:37:38,600 Speaker 1: and the batter is connected to the ground, and the 719 00:37:38,640 --> 00:37:41,720 Speaker 1: ground is connected to me, and there's air in between, 720 00:37:41,800 --> 00:37:45,160 Speaker 1: and there are photons flying back and forth, meaning like 721 00:37:45,160 --> 00:37:49,040 Speaker 1: like I am kind of inextricably tied to this baseball, 722 00:37:49,080 --> 00:37:51,520 Speaker 1: which means that I am now inside of a larger 723 00:37:51,560 --> 00:37:54,080 Speaker 1: box with the baseball exactly. Then that's why you don't 724 00:37:54,080 --> 00:37:56,359 Speaker 1: see quantum effects on big things, because big things are 725 00:37:56,400 --> 00:38:00,200 Speaker 1: always interacting, you know. Einstein famously asked somebody like, do 726 00:38:00,200 --> 00:38:02,880 Speaker 1: you believe the moon isn't there when you're not looking, 727 00:38:03,160 --> 00:38:05,360 Speaker 1: because he was thinking, like, it's silly to imagine that 728 00:38:05,400 --> 00:38:08,440 Speaker 1: the universe like is uncertain when you're not existing. And 729 00:38:08,480 --> 00:38:10,279 Speaker 1: the answer is like, of course the moon is there 730 00:38:10,360 --> 00:38:12,799 Speaker 1: because photons are hitting it and bouncing off of it, 731 00:38:13,160 --> 00:38:16,120 Speaker 1: and so the universe is always looking because the universe 732 00:38:16,200 --> 00:38:18,800 Speaker 1: is filled with particles and they're always sort of bouncing 733 00:38:18,840 --> 00:38:22,040 Speaker 1: off of things and gravity to right, it's interacting through 734 00:38:22,040 --> 00:38:24,440 Speaker 1: gravity with us. Oh, that's tricky because we don't know 735 00:38:24,480 --> 00:38:27,239 Speaker 1: if gravity is quantum mechanical and if there are gravitons 736 00:38:27,280 --> 00:38:30,400 Speaker 1: bouncing around through space. But in principle yes, and so 737 00:38:30,600 --> 00:38:33,359 Speaker 1: quantum de coherence is just like when an object no 738 00:38:33,440 --> 00:38:36,080 Speaker 1: longer becomes isolated and its wave function is now like 739 00:38:36,239 --> 00:38:39,560 Speaker 1: complicated lee mixed up with the rest of the environment 740 00:38:39,800 --> 00:38:42,239 Speaker 1: so that they don't like add up coherently anymore. Like 741 00:38:42,440 --> 00:38:44,160 Speaker 1: this little bit of the wave function is mixed up 742 00:38:44,200 --> 00:38:45,799 Speaker 1: with that part of the wave function from the bat, 743 00:38:46,000 --> 00:38:47,640 Speaker 1: and that part of the wave function from the ball 744 00:38:47,719 --> 00:38:49,080 Speaker 1: is mixed up with this other bit of the wave 745 00:38:49,120 --> 00:38:51,080 Speaker 1: function from the bat. And if you were outside the 746 00:38:51,120 --> 00:38:54,000 Speaker 1: baseball game, you could view the whole baseball games wave function. 747 00:38:54,200 --> 00:38:56,560 Speaker 1: Then you can say, oh, I still see quantum effects, right, 748 00:38:56,560 --> 00:38:58,479 Speaker 1: because I'm looking at the wave function of the whole 749 00:38:58,480 --> 00:39:02,279 Speaker 1: baseball game. But if you're inside, you are the batter, right, 750 00:39:02,360 --> 00:39:05,319 Speaker 1: then now you're only seeing one slice of it. All right. 751 00:39:05,360 --> 00:39:07,920 Speaker 1: Well it's weird because you know, I feel like the 752 00:39:07,960 --> 00:39:12,120 Speaker 1: word decoherence means that things get out of sink, but 753 00:39:12,280 --> 00:39:16,760 Speaker 1: really it means I got sucked into the box. Yeah, 754 00:39:16,800 --> 00:39:20,600 Speaker 1: you are entangled right and decoherent, right, Yeah, exactly. I 755 00:39:20,640 --> 00:39:23,280 Speaker 1: see how that's confusing. Yeah, it's more like I got 756 00:39:23,320 --> 00:39:26,399 Speaker 1: sucked into the box. But the word decoherence kind of, 757 00:39:26,600 --> 00:39:29,160 Speaker 1: you know, implies like some kind of like noise or 758 00:39:29,239 --> 00:39:31,319 Speaker 1: some kind of like breakdown of things. And I think 759 00:39:31,320 --> 00:39:33,479 Speaker 1: the key there is that, you know, just the ball 760 00:39:33,560 --> 00:39:36,319 Speaker 1: itself has not become decoherent. Are you no longer have 761 00:39:36,480 --> 00:39:38,560 Speaker 1: just a wave function that describes the ball. You have 762 00:39:38,640 --> 00:39:41,440 Speaker 1: to describe the ball and the bat or Jorge and 763 00:39:41,680 --> 00:39:44,319 Speaker 1: the cat. There's no way function by itself that now 764 00:39:44,400 --> 00:39:47,640 Speaker 1: describes the ball because the ball is entangled with the bat, 765 00:39:48,280 --> 00:39:51,759 Speaker 1: and so the balls isolated individual wave function is no 766 00:39:51,880 --> 00:39:55,400 Speaker 1: longer coherent. It's like a part of a larger wave function. 767 00:39:55,440 --> 00:39:57,640 Speaker 1: It can't be isolated. And so that's why you can't 768 00:39:57,680 --> 00:40:01,000 Speaker 1: get quantum effects on the ball anymore, because it's complicatedly 769 00:40:01,040 --> 00:40:02,680 Speaker 1: tied up with the things you want to use to 770 00:40:02,719 --> 00:40:05,520 Speaker 1: measure those quantum effects. Because we are the ball now, Daniel, 771 00:40:06,120 --> 00:40:09,279 Speaker 1: the ball on us are one. That's what decoherence means, right, 772 00:40:09,360 --> 00:40:12,239 Speaker 1: kind of like it. It gets so complicated. I guess 773 00:40:12,280 --> 00:40:14,400 Speaker 1: that's why we use the word decoherence, just because it 774 00:40:14,960 --> 00:40:19,520 Speaker 1: gets complicated beyond our ability to be outside the box. 775 00:40:19,560 --> 00:40:22,479 Speaker 1: It's like we're in the box now and we can't 776 00:40:22,560 --> 00:40:27,279 Speaker 1: make out what these quantumness effects are. Yeah, exactly, it's 777 00:40:27,320 --> 00:40:29,319 Speaker 1: too much for us to calculate, too much for us 778 00:40:29,320 --> 00:40:32,880 Speaker 1: to understand. And so what happens is that quantum mechanics 779 00:40:32,920 --> 00:40:35,920 Speaker 1: doesn't fail, doesn't go away. This is just what quantum 780 00:40:35,960 --> 00:40:39,759 Speaker 1: mechanics looks like at a big scale. Quantum mechanics over 781 00:40:39,840 --> 00:40:43,120 Speaker 1: zillions and zillions of objects. Looks different because you don't 782 00:40:43,120 --> 00:40:45,799 Speaker 1: see those coherent effects anymore. They only exist when you 783 00:40:45,840 --> 00:40:48,040 Speaker 1: have like one or two or three little things that 784 00:40:48,160 --> 00:40:50,080 Speaker 1: you can keep separated, so you can have a wave 785 00:40:50,120 --> 00:40:53,640 Speaker 1: function just for that. When you're part of the wave function, 786 00:40:53,880 --> 00:40:56,480 Speaker 1: quantum mechanics says that things look different. They look more 787 00:40:56,600 --> 00:40:59,520 Speaker 1: smeared and averaged out. So it's not like classical physics 788 00:40:59,640 --> 00:41:02,600 Speaker 1: is in agreement with quantum mechanics. It's what quantum mechanics 789 00:41:02,640 --> 00:41:05,120 Speaker 1: looks like, sort of from a high altitude, right, like, 790 00:41:05,200 --> 00:41:08,440 Speaker 1: to an alien observer outside of our universe, we are 791 00:41:08,480 --> 00:41:11,360 Speaker 1: still all coherent. We are you and I and this 792 00:41:11,440 --> 00:41:15,080 Speaker 1: podcast and that baseball. It still looks like a pristine 793 00:41:15,640 --> 00:41:18,920 Speaker 1: quantum universe. Yeah, and I hope that alien that has 794 00:41:18,960 --> 00:41:21,920 Speaker 1: that deep understanding quantum mechanics has a coherent understanding of 795 00:41:21,960 --> 00:41:24,240 Speaker 1: what we've been talking about today, because it's gotten pretty 796 00:41:24,239 --> 00:41:29,840 Speaker 1: tricky al right. Well, I think hopefully that gives people 797 00:41:29,880 --> 00:41:32,319 Speaker 1: a sense of kind of the issues involved. You know, 798 00:41:32,400 --> 00:41:35,719 Speaker 1: it's kind of about what you consider the box to be, 799 00:41:36,120 --> 00:41:40,279 Speaker 1: what's interacting with what, and how these kind of probabilities 800 00:41:40,440 --> 00:41:42,880 Speaker 1: add up or don't add up, And it's not just 801 00:41:42,960 --> 00:41:45,600 Speaker 1: like an academic question or a philosophical question. It's actually 802 00:41:45,680 --> 00:41:49,200 Speaker 1: really important for quantum computing. If you want to build 803 00:41:49,200 --> 00:41:52,400 Speaker 1: a quantum computer, you need cubits. You need weird particles 804 00:41:52,400 --> 00:41:54,840 Speaker 1: that follow quantum rules so you can have them do 805 00:41:55,000 --> 00:41:58,000 Speaker 1: quantum computations. And to do that, you need to keep 806 00:41:58,040 --> 00:42:01,240 Speaker 1: them isolated. And that's okay to do for one cubit, 807 00:42:01,239 --> 00:42:04,520 Speaker 1: two cubits, three cubits, But imagine having a really big 808 00:42:04,600 --> 00:42:08,080 Speaker 1: quantum computer with thousands and thousands of cubans or millions 809 00:42:08,160 --> 00:42:11,239 Speaker 1: or trillions, right, you gotta keep them all isolated and 810 00:42:11,320 --> 00:42:15,120 Speaker 1: all individually coherent. It becomes really difficult. So this is 811 00:42:15,120 --> 00:42:18,640 Speaker 1: something people are literally working on, is building larger coherent 812 00:42:18,719 --> 00:42:23,080 Speaker 1: quantum systems. Yeah. I can't wait for that quantum phone 813 00:42:23,880 --> 00:42:26,920 Speaker 1: so I can take quantum pictures of my kids playing 814 00:42:27,080 --> 00:42:29,799 Speaker 1: quantum So you can ignore that email and answer it 815 00:42:29,840 --> 00:42:33,200 Speaker 1: at the same time. Yeah, that's right, So I can 816 00:42:33,400 --> 00:42:36,680 Speaker 1: do everything at the same time, exactly. And this is 817 00:42:36,719 --> 00:42:39,800 Speaker 1: really closely connected to deep issues and the philosophy of 818 00:42:39,880 --> 00:42:43,040 Speaker 1: quantum mechanics. You know who's doing the observing, why does 819 00:42:43,080 --> 00:42:45,400 Speaker 1: it matter? When does the wave function collapse? And I 820 00:42:45,480 --> 00:42:47,359 Speaker 1: want to have another episode where we talk about wave 821 00:42:47,360 --> 00:42:49,879 Speaker 1: functional collapse in the measurement problem. But this is sort 822 00:42:49,920 --> 00:42:51,479 Speaker 1: of like a warm up to that because it helps 823 00:42:51,480 --> 00:42:55,440 Speaker 1: you understand, you know why sometimes the probabilities are more 824 00:42:55,480 --> 00:42:59,399 Speaker 1: classical instead of quantum mechanical. Quantum coherence tells you, like, 825 00:42:59,560 --> 00:43:02,480 Speaker 1: you know, it's likely to happen. It doesn't explain why 826 00:43:02,760 --> 00:43:06,080 Speaker 1: it collapses from two possibilities down to one actual thing. 827 00:43:07,680 --> 00:43:10,160 Speaker 1: That's the tricky part. That's one of the tricky parts. 828 00:43:10,160 --> 00:43:12,160 Speaker 1: That's the trickiest part. It's all tricky. But you just 829 00:43:12,239 --> 00:43:15,800 Speaker 1: have to get inside the box and then it's not tricky. Yeah, exactly, 830 00:43:15,920 --> 00:43:18,560 Speaker 1: Then you understand it. You don't understand just like the cat, 831 00:43:18,719 --> 00:43:20,680 Speaker 1: Yeah exactly. If you want quantum mechanics to go away, 832 00:43:20,760 --> 00:43:23,640 Speaker 1: just you know, only work on big, complicated systems where 833 00:43:23,719 --> 00:43:27,160 Speaker 1: those effects don't appear because they're all decoherent. All right, Well, 834 00:43:27,320 --> 00:43:30,400 Speaker 1: we hope you enjoyed dad and got a better sense 835 00:43:30,520 --> 00:43:34,919 Speaker 1: of quantum mechanics. Thanks for joining us, See you next time. 836 00:43:42,840 --> 00:43:45,640 Speaker 1: Thanks for listening, and remember that Daniel and Jorge Explain 837 00:43:45,680 --> 00:43:48,600 Speaker 1: the Universe is a production of I Heart Radio or 838 00:43:48,719 --> 00:43:51,600 Speaker 1: more podcast from my heart Radio. Visit the I heart 839 00:43:51,719 --> 00:43:55,319 Speaker 1: Radio app Apple podcasts or wherever you listen to your 840 00:43:55,360 --> 00:44:01,680 Speaker 1: favorite shows. No.