1 00:00:08,560 --> 00:00:11,520 Speaker 1: Once upon a time, physicists seemed to have the world 2 00:00:11,600 --> 00:00:15,440 Speaker 1: figured out almost There were one or two loose threads 3 00:00:15,480 --> 00:00:18,200 Speaker 1: to be tidied up, but a solid idea about how 4 00:00:18,239 --> 00:00:21,920 Speaker 1: the universe worked had emerged, and it made sense. At 5 00:00:21,920 --> 00:00:25,759 Speaker 1: a particle level, physicist thought the universe worked basically the 6 00:00:25,840 --> 00:00:28,120 Speaker 1: same way it did at the human level and at 7 00:00:28,160 --> 00:00:32,240 Speaker 1: the planetary level little balls moving around, orbiting each other, 8 00:00:32,400 --> 00:00:36,159 Speaker 1: occasionally even careening off of each other. How wonderful and 9 00:00:36,240 --> 00:00:39,880 Speaker 1: symmetric and symbol it seemed that the same concepts worked 10 00:00:39,920 --> 00:00:43,040 Speaker 1: from the very small to the very large. What a deep, 11 00:00:43,400 --> 00:00:47,080 Speaker 1: satisfying truth about the universe we had revealed that explained 12 00:00:47,120 --> 00:00:52,159 Speaker 1: almost everything other than a few pesky experimental results, And 13 00:00:52,200 --> 00:00:56,760 Speaker 1: then those remaining loose threads unraveled the whole picture. To 14 00:00:56,880 --> 00:01:00,440 Speaker 1: explain those weird experiments, we needed to break that symmetry 15 00:01:00,440 --> 00:01:02,600 Speaker 1: and come up with a new vision for how the 16 00:01:02,720 --> 00:01:06,280 Speaker 1: microscopic world works. At the smallest level, the world wasn't 17 00:01:06,319 --> 00:01:08,960 Speaker 1: made of little spinning balls, but of something new and 18 00:01:09,040 --> 00:01:12,480 Speaker 1: quite alien, quantum objects that followed a weird set of 19 00:01:12,560 --> 00:01:15,000 Speaker 1: rules that gave headaches to even the geniuses of the 20 00:01:15,040 --> 00:01:18,960 Speaker 1: twentieth century. So then, what is real. Is the world 21 00:01:19,040 --> 00:01:22,520 Speaker 1: made of stuff that moves through space like basketballs and planets? 22 00:01:22,800 --> 00:01:25,880 Speaker 1: Or does it follow some crazy new, weird quantum rules. 23 00:01:26,040 --> 00:01:28,440 Speaker 1: And if the quantum rules are real, does that mean 24 00:01:28,480 --> 00:01:46,960 Speaker 1: that the universe doesn't make any sense deep down? Hi? 25 00:01:47,160 --> 00:01:50,480 Speaker 1: I'm Daniel. I'm a particle physicist and I'm desperate to 26 00:01:50,520 --> 00:01:54,120 Speaker 1: know what is real about the universe. And with me 27 00:01:54,160 --> 00:01:58,400 Speaker 1: today is a special guest astrophysicist Adam Becker, and an 28 00:01:58,480 --> 00:02:01,640 Speaker 1: expert on reality, given that he's written a wonderful book 29 00:02:01,640 --> 00:02:05,280 Speaker 1: about quantum mechanics titled What Is Real? Adam, Welcome to 30 00:02:05,280 --> 00:02:08,320 Speaker 1: the program. Say hello, Hi, Yeah, thanks for having me Daniel. 31 00:02:08,360 --> 00:02:10,639 Speaker 1: This is a lot of fun. Well, I'm especially pleased 32 00:02:10,680 --> 00:02:13,480 Speaker 1: to have you on today because when listeners right in 33 00:02:13,520 --> 00:02:15,600 Speaker 1: and ask me what they can read to get a 34 00:02:15,639 --> 00:02:18,840 Speaker 1: better understanding of the thorny problems of quantum mechanics, I 35 00:02:18,880 --> 00:02:21,720 Speaker 1: always recommend your book. So thanks for joining us and 36 00:02:21,760 --> 00:02:24,120 Speaker 1: for helping us unravel a little bit about what we 37 00:02:24,200 --> 00:02:27,079 Speaker 1: know and what we don't know about the universe. Well 38 00:02:27,120 --> 00:02:29,560 Speaker 1: that's great. I'm really glad to hear that you're plugging 39 00:02:29,639 --> 00:02:34,480 Speaker 1: my book And welcome everybody to the podcast. Daniel and 40 00:02:34,560 --> 00:02:36,920 Speaker 1: Jorhigg explain in the universe where we try to do 41 00:02:37,080 --> 00:02:40,400 Speaker 1: just that, embrace our knowledge and admit our ignorance. We 42 00:02:40,440 --> 00:02:42,640 Speaker 1: do a deep dive into what things really mean and 43 00:02:42,680 --> 00:02:45,120 Speaker 1: admit when words and science are being used to describe 44 00:02:45,120 --> 00:02:48,520 Speaker 1: our lack of knowledge rather than our actual understanding. We're 45 00:02:48,600 --> 00:02:50,680 Speaker 1: here to explain all of it to you, and on 46 00:02:50,720 --> 00:02:53,919 Speaker 1: today's program, we're gonna attempt to do something very hard, 47 00:02:54,160 --> 00:02:57,919 Speaker 1: to tackle one of the trickiest topics in modern physics, 48 00:02:57,960 --> 00:03:01,400 Speaker 1: the meaning of quantum mechanics. But our goal is to 49 00:03:01,480 --> 00:03:04,240 Speaker 1: find the solution today, but instead to help guide you 50 00:03:04,360 --> 00:03:08,200 Speaker 1: through the current situation, the status of our knowledge and ignorance, 51 00:03:08,360 --> 00:03:10,760 Speaker 1: to show you where the tricky bits are, why they 52 00:03:10,800 --> 00:03:14,240 Speaker 1: have been so persistently tricky, and what the various ideas 53 00:03:14,280 --> 00:03:17,000 Speaker 1: are for making progress. I mean, we know that quantum 54 00:03:17,040 --> 00:03:19,920 Speaker 1: mechanics works right, the math is correct, it can predict 55 00:03:19,919 --> 00:03:22,920 Speaker 1: the results of experiments with incredible precision. It seems like 56 00:03:22,919 --> 00:03:26,000 Speaker 1: our universe is quantum mechanical. But we want to know 57 00:03:26,160 --> 00:03:28,600 Speaker 1: what that means about the universe. We want to know 58 00:03:28,800 --> 00:03:32,200 Speaker 1: what is real to me. That's what physics is is 59 00:03:32,240 --> 00:03:35,640 Speaker 1: explaining the unknown in terms of the known. Is grappling 60 00:03:35,640 --> 00:03:37,920 Speaker 1: with it and getting our intuition around it. So my 61 00:03:38,040 --> 00:03:40,960 Speaker 1: first question to you, Adam, is do you think that's possible? 62 00:03:41,200 --> 00:03:43,760 Speaker 1: Do we even have the tools, the mental tools to 63 00:03:43,920 --> 00:03:48,040 Speaker 1: explain and understand something this alien, to understand what is real? 64 00:03:48,280 --> 00:03:53,080 Speaker 1: I mean, hopefully, because that's the short answer. The longer 65 00:03:53,080 --> 00:03:55,400 Speaker 1: answer is, you know, so far we seem to be 66 00:03:55,400 --> 00:03:58,680 Speaker 1: doing a pretty okay job. I am certainly open to 67 00:03:58,720 --> 00:04:02,760 Speaker 1: the possibility that the human mind is just not capable 68 00:04:02,760 --> 00:04:06,400 Speaker 1: of comprehending some basic features of reality. On the other hand, 69 00:04:06,600 --> 00:04:09,240 Speaker 1: you know, throughout the history of science, we've got a 70 00:04:09,240 --> 00:04:11,880 Speaker 1: pretty good track record of you know, banging our heads 71 00:04:11,880 --> 00:04:14,800 Speaker 1: against a problem and eventually coming up with a pretty 72 00:04:14,800 --> 00:04:17,400 Speaker 1: good theory of what's going on in a pretty good mathematical, 73 00:04:17,720 --> 00:04:21,880 Speaker 1: you know, description to go along with that theory. Quantum mechanics, 74 00:04:22,040 --> 00:04:26,840 Speaker 1: of course, is deeply strange, but there's no rule against 75 00:04:26,839 --> 00:04:29,279 Speaker 1: reality being strange. Right. In fact, it be kind of 76 00:04:29,279 --> 00:04:33,159 Speaker 1: weird if the world we're not weird, be disappointing, yeah, exactly. Yeah, 77 00:04:33,160 --> 00:04:35,359 Speaker 1: And also, come on, have you been here? Have you 78 00:04:35,400 --> 00:04:37,760 Speaker 1: seen this place? Of course it's weird, but you're toutings 79 00:04:37,760 --> 00:04:40,440 Speaker 1: are the history of our accomplishments, and those are wonderful, 80 00:04:40,600 --> 00:04:42,359 Speaker 1: but a lot of those are limited to sort of 81 00:04:42,360 --> 00:04:46,040 Speaker 1: the the narrow regime in which our intuition works, right, 82 00:04:46,279 --> 00:04:49,279 Speaker 1: because we grew up experiencing at things, These are familiar 83 00:04:49,360 --> 00:04:52,360 Speaker 1: questions we have. Why does the thing roll down the hill? 84 00:04:52,600 --> 00:04:55,640 Speaker 1: What are these stars moving around us? Does that necessarily 85 00:04:55,640 --> 00:04:59,719 Speaker 1: mean it's possible to like extrapolate to other weird realms 86 00:04:59,760 --> 00:05:01,640 Speaker 1: where just have not grown up with any sort of 87 00:05:01,839 --> 00:05:05,080 Speaker 1: natural experience. Yeah, I mean not necessarily. It's possible that 88 00:05:05,120 --> 00:05:07,480 Speaker 1: we'll hit some sort of limit. I'm just not convinced 89 00:05:07,560 --> 00:05:10,640 Speaker 1: that quantum mechanics represents that limit. I mean, first of all, 90 00:05:10,680 --> 00:05:15,800 Speaker 1: we have this phenomenally accurate and precise theory in quantum 91 00:05:15,800 --> 00:05:18,719 Speaker 1: mechanics and quantum physics more generally, you know, arguably the 92 00:05:18,720 --> 00:05:22,240 Speaker 1: most accurate scientific theory ever in terms of, you know, 93 00:05:22,320 --> 00:05:26,560 Speaker 1: how well it matches experiment. And it's not as if 94 00:05:27,040 --> 00:05:29,640 Speaker 1: we've looked at the theory and thrown up our hands 95 00:05:29,640 --> 00:05:32,360 Speaker 1: and said, you know, this is impossible to understand. We have, 96 00:05:32,520 --> 00:05:34,880 Speaker 1: you know, mathematical tools, but there's no way that the 97 00:05:34,960 --> 00:05:38,320 Speaker 1: human mind can comprehend the reality behind the math. If anything, 98 00:05:38,320 --> 00:05:42,279 Speaker 1: it's the opposite. We have too many ideas about how 99 00:05:42,320 --> 00:05:44,839 Speaker 1: to understand the reality behind the math. So that doesn't 100 00:05:44,920 --> 00:05:49,600 Speaker 1: sound like a failure of human intuition to me, at 101 00:05:49,680 --> 00:05:52,000 Speaker 1: least not yet. You know. Yeah, I'm totally open to 102 00:05:52,040 --> 00:05:54,000 Speaker 1: the idea that we'll get there at some point. All right, Well, 103 00:05:54,040 --> 00:05:56,360 Speaker 1: you sound like a supporter of quantum mechanics. In fact, 104 00:05:56,440 --> 00:05:59,919 Speaker 1: it sounds like you're a shill for Big Quantum. You know. 105 00:06:00,120 --> 00:06:02,560 Speaker 1: I don't think anyone has ever accused me of being 106 00:06:02,600 --> 00:06:05,760 Speaker 1: a shill for a big quantum before. But I can't 107 00:06:05,880 --> 00:06:09,200 Speaker 1: say that you're wrong. I'm just not exactly a paid shill. 108 00:06:09,400 --> 00:06:11,520 Speaker 1: There's no money in it. Oh you're not getting your checks? 109 00:06:11,520 --> 00:06:13,640 Speaker 1: Oh man? Yeah, well I not from big Quantum, just 110 00:06:13,680 --> 00:06:17,960 Speaker 1: from the publisher. Well, we can't tagle all of qualum 111 00:06:18,000 --> 00:06:20,400 Speaker 1: mechanics in a single episode, so today I want to 112 00:06:20,400 --> 00:06:23,680 Speaker 1: focus on one issue in particular, which is I think 113 00:06:23,720 --> 00:06:26,400 Speaker 1: at the heart of it all and sometimes known as 114 00:06:26,440 --> 00:06:29,800 Speaker 1: the measurement problem. So on today's program, we're asking the 115 00:06:29,920 --> 00:06:39,520 Speaker 1: question what makes the wave function collapse? What is measurement 116 00:06:39,720 --> 00:06:42,920 Speaker 1: in quantum mechanics? And Adam, before we dig into it, 117 00:06:43,080 --> 00:06:45,000 Speaker 1: we do something fun on the program, which is that 118 00:06:45,040 --> 00:06:47,719 Speaker 1: I ask our listeners to answer this question just to 119 00:06:47,720 --> 00:06:50,120 Speaker 1: get a sense for like what out there are people thinking, 120 00:06:50,320 --> 00:06:52,360 Speaker 1: How much of a grass to people have on this question. 121 00:06:52,400 --> 00:06:55,320 Speaker 1: It helps orient us to know where to aim our answer. 122 00:06:55,680 --> 00:06:59,120 Speaker 1: So I have for us some clips from listeners, and 123 00:06:59,160 --> 00:07:02,200 Speaker 1: if you they're listening, would like to participate for future 124 00:07:02,240 --> 00:07:06,240 Speaker 1: episodes to answer really hard physics questions with no preparation. 125 00:07:06,440 --> 00:07:09,080 Speaker 1: Please write to me two questions at Daniel and Jorge 126 00:07:09,120 --> 00:07:11,400 Speaker 1: dot com. It's a lot more fun than it's outs. 127 00:07:11,840 --> 00:07:15,200 Speaker 1: Here's what our listeners had to say. Okay, I have 128 00:07:16,160 --> 00:07:21,640 Speaker 1: I've been learning about wave functions and quantum physics and 129 00:07:21,680 --> 00:07:23,960 Speaker 1: I think I know that's a really important part of 130 00:07:24,000 --> 00:07:28,160 Speaker 1: measuring something, and I have heard about it collapsing, but 131 00:07:28,200 --> 00:07:29,800 Speaker 1: I'm not sure what makes the collapse. I'm going to 132 00:07:29,880 --> 00:07:33,480 Speaker 1: guess that what makes a wave function collapse is when 133 00:07:34,680 --> 00:07:38,800 Speaker 1: um something's measured. I would say, once the energy in 134 00:07:38,920 --> 00:07:42,800 Speaker 1: the wave is reduced to a certain point, the wave 135 00:07:42,880 --> 00:07:47,680 Speaker 1: can no longer support itself and it collapses. I'm just 136 00:07:47,760 --> 00:07:57,320 Speaker 1: going to guess here, probably something that intervenes from outside 137 00:07:57,400 --> 00:08:05,520 Speaker 1: so on outside interaction. Alright, So those the answers from 138 00:08:05,560 --> 00:08:08,880 Speaker 1: our awesome listeners Adam, what do you think about those speculations. 139 00:08:09,160 --> 00:08:12,160 Speaker 1: I mean, they mostly sound like the kinds of things 140 00:08:12,160 --> 00:08:15,920 Speaker 1: that you would see in a quantum mechanics textbook actually, 141 00:08:16,320 --> 00:08:19,960 Speaker 1: which is to say kind of fake. Right. There's a 142 00:08:19,960 --> 00:08:22,120 Speaker 1: lot of talking there about like, well, I'm not sure 143 00:08:22,320 --> 00:08:25,560 Speaker 1: something about measurement, but I don't really know what that means, 144 00:08:25,680 --> 00:08:28,520 Speaker 1: and like that's really the heart of the problem, right, 145 00:08:28,520 --> 00:08:31,320 Speaker 1: Like nobody really knows what we mean by measurement or 146 00:08:31,320 --> 00:08:34,319 Speaker 1: by observation. So we like have a word for it, 147 00:08:34,600 --> 00:08:36,480 Speaker 1: we have a phrase for but we don't really know 148 00:08:36,640 --> 00:08:39,839 Speaker 1: exactly what that means is happening deep down. Yeah, that's 149 00:08:39,880 --> 00:08:42,880 Speaker 1: exactly right, all right, So I think maybe we should 150 00:08:42,920 --> 00:08:45,920 Speaker 1: start just by orienting ourselves, just by getting sort of 151 00:08:45,920 --> 00:08:48,720 Speaker 1: like using the same vocabulary and making sure everybody out 152 00:08:48,720 --> 00:08:51,000 Speaker 1: there knows what we're talking about when we say the 153 00:08:51,040 --> 00:08:54,120 Speaker 1: wave function, Can you give us a short definition of 154 00:08:54,120 --> 00:08:56,120 Speaker 1: what the wave function is and why it's so important 155 00:08:56,160 --> 00:08:58,400 Speaker 1: to this question. I mean, there's a sense in which 156 00:08:58,400 --> 00:09:00,680 Speaker 1: the question of what the wave function is kind of 157 00:09:00,720 --> 00:09:02,720 Speaker 1: what's at the heart of all this too. But yeah, 158 00:09:02,840 --> 00:09:05,000 Speaker 1: I can take a stab of that's so in sort 159 00:09:05,040 --> 00:09:09,520 Speaker 1: of classical physics, the physics of Isaac Newton, the physics 160 00:09:09,600 --> 00:09:12,560 Speaker 1: of everyday life, the physics of you know, billiard balls 161 00:09:12,880 --> 00:09:17,640 Speaker 1: and car crashes. The way that we describe where things are. 162 00:09:18,000 --> 00:09:21,199 Speaker 1: We usually use three numbers to describe where something is, 163 00:09:21,280 --> 00:09:23,360 Speaker 1: or at least where the center of mass of something is. 164 00:09:23,600 --> 00:09:25,240 Speaker 1: You know, we say, okay, well, here's where it is 165 00:09:25,240 --> 00:09:27,240 Speaker 1: in the X, y and z. Here's how high off 166 00:09:27,280 --> 00:09:29,640 Speaker 1: the ground it is. Here's how far in front of 167 00:09:29,679 --> 00:09:31,440 Speaker 1: me it is, and here's how far it is off 168 00:09:31,480 --> 00:09:34,000 Speaker 1: to one side. And that's all you really need to 169 00:09:34,040 --> 00:09:36,640 Speaker 1: describe where something is, because we live in a three 170 00:09:36,640 --> 00:09:41,400 Speaker 1: dimensional world exactly right. But in quantum mechanics, if you 171 00:09:41,440 --> 00:09:43,160 Speaker 1: want to do the same thing, if you want to 172 00:09:43,200 --> 00:09:46,600 Speaker 1: take all the information we have about where something is, 173 00:09:46,800 --> 00:09:48,920 Speaker 1: like if you want to talk about where an electron is, 174 00:09:49,240 --> 00:09:52,440 Speaker 1: you need more than three numbers. You actually need on 175 00:09:52,520 --> 00:09:56,720 Speaker 1: infinity of numbers spread out across all of space. And 176 00:09:57,520 --> 00:10:00,080 Speaker 1: that's the wave function. So the numbers are higher in 177 00:10:00,160 --> 00:10:04,360 Speaker 1: some spots and lower in others. And usually what we 178 00:10:04,520 --> 00:10:07,400 Speaker 1: say the wave function represents is that it's to do 179 00:10:07,600 --> 00:10:12,280 Speaker 1: with the probability of finding the electron in a particular 180 00:10:12,440 --> 00:10:16,480 Speaker 1: spot when we look, which makes it sound like the 181 00:10:16,480 --> 00:10:20,320 Speaker 1: wave function isn't really a thing in nature, and it's 182 00:10:20,360 --> 00:10:23,440 Speaker 1: just a lot more about our information. Yeah, so hold 183 00:10:23,440 --> 00:10:25,520 Speaker 1: on it. Let me ask you about that, because you're 184 00:10:25,520 --> 00:10:28,280 Speaker 1: making an analogy to a classical particle where we're talking 185 00:10:28,320 --> 00:10:31,200 Speaker 1: about like where it actually is, and you're saying that 186 00:10:31,360 --> 00:10:34,200 Speaker 1: you need more information to talk about where an electron is. 187 00:10:34,480 --> 00:10:36,880 Speaker 1: But now you're describing the wave function in terms not 188 00:10:37,200 --> 00:10:39,600 Speaker 1: of where the object is or what it is, but 189 00:10:39,679 --> 00:10:42,520 Speaker 1: about our measurements of it already, sort of like we've 190 00:10:42,520 --> 00:10:45,400 Speaker 1: already sort of snuck into the electron. That's exactly right. 191 00:10:45,400 --> 00:10:48,880 Speaker 1: I mean, there's there are I wasn't kidding when I 192 00:10:48,880 --> 00:10:50,520 Speaker 1: said that, you know, the question of what the wave 193 00:10:50,559 --> 00:10:52,960 Speaker 1: function is it's sort of part of the controversy here 194 00:10:53,000 --> 00:10:55,000 Speaker 1: and part of what's at stake. We'll see if we 195 00:10:55,000 --> 00:10:58,040 Speaker 1: get past this one question and the whole thing exactly. Yeah. 196 00:10:58,320 --> 00:11:01,679 Speaker 1: I'm not convinced succeed, but yeah, I mean the reason 197 00:11:01,800 --> 00:11:06,360 Speaker 1: I say, oh, this is sort of the quantum analog 198 00:11:07,160 --> 00:11:10,559 Speaker 1: of you know, the three numbers describing where something is 199 00:11:10,640 --> 00:11:13,040 Speaker 1: in Newton's physics is that, you know, it sort of 200 00:11:13,080 --> 00:11:16,800 Speaker 1: plays the same role in the same sorts of physical 201 00:11:17,000 --> 00:11:21,760 Speaker 1: laws in quantum physics. So the question of whether the 202 00:11:21,800 --> 00:11:24,480 Speaker 1: wave function is a thing out in the world or 203 00:11:24,480 --> 00:11:27,680 Speaker 1: if it's just something about our information about stuff out 204 00:11:27,720 --> 00:11:32,040 Speaker 1: in the world is you know, a live question and 205 00:11:32,160 --> 00:11:35,480 Speaker 1: a subject of active debate. But it's not just as 206 00:11:35,520 --> 00:11:39,720 Speaker 1: simple as saying, oh, it's just our information about what's 207 00:11:39,720 --> 00:11:41,920 Speaker 1: out there. It's just that in the most simple way 208 00:11:41,960 --> 00:11:45,959 Speaker 1: imaginable because wave functions, I mean, like the name sort 209 00:11:46,000 --> 00:11:50,719 Speaker 1: of implies the wave functions. Wave they behave in ways 210 00:11:50,840 --> 00:11:54,800 Speaker 1: that we actually tend to associate with physical objects. They 211 00:11:54,920 --> 00:11:59,400 Speaker 1: undulate smoothly, the numbers change smoothly from one place to another, 212 00:11:59,440 --> 00:12:02,120 Speaker 1: they change over time, and they can even perform some 213 00:12:02,200 --> 00:12:05,000 Speaker 1: of the same tricks that waves perform. You can send 214 00:12:05,320 --> 00:12:09,840 Speaker 1: them through a narrow slit and they'll defract outward on 215 00:12:09,880 --> 00:12:13,120 Speaker 1: the other side. They can interfere with themselves and cause 216 00:12:13,200 --> 00:12:16,200 Speaker 1: you know, patterns of light and darkness on a photographic plate, 217 00:12:16,280 --> 00:12:18,079 Speaker 1: that sort of thing. So we call it a wave 218 00:12:18,120 --> 00:12:21,880 Speaker 1: function because mathematically it's described by similar equations to describe 219 00:12:21,880 --> 00:12:24,800 Speaker 1: other kind of classical waves were familiar with, that's right, yeah, 220 00:12:24,840 --> 00:12:27,640 Speaker 1: And it also performs some of the same tricks as 221 00:12:27,720 --> 00:12:30,840 Speaker 1: classical waves that were familiar with physically, so you know, 222 00:12:30,920 --> 00:12:34,280 Speaker 1: we don't tend to think of our information about a 223 00:12:34,400 --> 00:12:38,760 Speaker 1: thing as doing that. And it doesn't mean that it can't. 224 00:12:38,800 --> 00:12:41,120 Speaker 1: It just means that if we want an account of 225 00:12:41,160 --> 00:12:43,840 Speaker 1: wave functions in terms of our information about the world, 226 00:12:43,920 --> 00:12:46,000 Speaker 1: as opposed to saying, you know, the wave functions actually 227 00:12:46,000 --> 00:12:47,920 Speaker 1: a wave that's out there, we need to do some 228 00:12:47,960 --> 00:12:50,560 Speaker 1: extra work. So you're saying the wave function tells us 229 00:12:51,080 --> 00:12:53,840 Speaker 1: how to predict the outcomes of our experiments, like if 230 00:12:53,840 --> 00:12:55,560 Speaker 1: I'm going to find the electron over here, or if 231 00:12:55,559 --> 00:12:57,160 Speaker 1: I'm gonna find it over there, or if I'm gonna 232 00:12:57,200 --> 00:12:59,319 Speaker 1: find it's been up or going to find it's been down. 233 00:12:59,360 --> 00:13:01,840 Speaker 1: It tells me what I'm likely to observe, but we're 234 00:13:01,840 --> 00:13:05,520 Speaker 1: not sure whether it's like actually real and distinct separate 235 00:13:05,559 --> 00:13:08,040 Speaker 1: from our ability to measure it and interact with it. 236 00:13:08,080 --> 00:13:10,559 Speaker 1: We don't know sort of philosophically, whether we can take 237 00:13:10,600 --> 00:13:13,640 Speaker 1: that step. Yeah, yeah, I mean, there are theorems that 238 00:13:13,720 --> 00:13:15,920 Speaker 1: suggests that there's something like the way function out in 239 00:13:15,960 --> 00:13:18,920 Speaker 1: the world, but it's not. You know, this is an 240 00:13:18,920 --> 00:13:22,400 Speaker 1: open question and has been since the beginning of quantum 241 00:13:22,400 --> 00:13:24,600 Speaker 1: physics almost addrey years ago. And I think that's sort 242 00:13:24,600 --> 00:13:26,880 Speaker 1: of one of the most fascinating points. I mean, you 243 00:13:26,960 --> 00:13:30,839 Speaker 1: talk about classical physics, there's no distinction there between the 244 00:13:30,880 --> 00:13:34,280 Speaker 1: thing exists and we measure it to exist there. It's 245 00:13:34,280 --> 00:13:35,880 Speaker 1: just like those two things are just part of the 246 00:13:35,920 --> 00:13:39,640 Speaker 1: same idea. You see the ball there because it is there, right, 247 00:13:39,640 --> 00:13:41,440 Speaker 1: and it would be there if you weren't here to 248 00:13:41,520 --> 00:13:43,560 Speaker 1: look at it as all this kind of stuff. So 249 00:13:43,640 --> 00:13:46,240 Speaker 1: I love these discoveries and physics that make us sort 250 00:13:46,240 --> 00:13:50,520 Speaker 1: of crack open two ideas we thought were so naturally entangled, 251 00:13:50,720 --> 00:13:53,160 Speaker 1: so like deeply connected, and now we realize there's a 252 00:13:53,160 --> 00:13:55,920 Speaker 1: possibility for these two things to be actually separate and distinct. 253 00:13:56,000 --> 00:14:00,000 Speaker 1: Observing something is there doesn't mean that it is there 254 00:14:00,160 --> 00:14:03,840 Speaker 1: some deeper sense. It's like totally crazy. Yeah, no, it's 255 00:14:03,920 --> 00:14:09,000 Speaker 1: it's absolutely true. And one of the strange things about 256 00:14:09,200 --> 00:14:12,000 Speaker 1: wave functions and measurement is just the idea that, you know, 257 00:14:12,720 --> 00:14:16,079 Speaker 1: measurement and observation are coming into what's supposed to be 258 00:14:16,120 --> 00:14:18,680 Speaker 1: a fundamental theory at all, because you know, measurement is 259 00:14:18,679 --> 00:14:22,200 Speaker 1: not a well defined thing. What do we mean when 260 00:14:22,200 --> 00:14:24,800 Speaker 1: we say measurement? Right? And I think that a key 261 00:14:24,880 --> 00:14:27,520 Speaker 1: concept we need to tackle before we get into measurement 262 00:14:27,880 --> 00:14:31,680 Speaker 1: is this question of superposition, right, because quantum mechanical objects 263 00:14:31,680 --> 00:14:35,120 Speaker 1: can do something that like our baseballs can't do, which 264 00:14:35,160 --> 00:14:37,360 Speaker 1: is that they can for a long time, have two 265 00:14:37,400 --> 00:14:41,520 Speaker 1: possible outcomes and maintain those two possibilities simultaneously. Right, So 266 00:14:41,600 --> 00:14:45,960 Speaker 1: the wave function can incorporate various possible outcomes inside of itself. Yeah, 267 00:14:46,080 --> 00:14:49,840 Speaker 1: now that that's exactly right. If you send uh ping 268 00:14:49,920 --> 00:14:53,040 Speaker 1: pong ball into a maze, it's just gonna go down 269 00:14:53,080 --> 00:14:55,160 Speaker 1: one path in that maze and you can watch it 270 00:14:55,280 --> 00:14:58,040 Speaker 1: take one path. But if you send an electron or 271 00:14:58,040 --> 00:15:00,800 Speaker 1: a photon or some other you know, tinique wantum object 272 00:15:00,960 --> 00:15:03,880 Speaker 1: into you know, some sort of maze, like send a 273 00:15:03,880 --> 00:15:06,680 Speaker 1: photon into a set of mirrors and prisms on an 274 00:15:06,680 --> 00:15:08,680 Speaker 1: optical bench, you know, in the basement of a physics 275 00:15:08,680 --> 00:15:11,160 Speaker 1: department somewhere. It's not going to take just one path. 276 00:15:11,480 --> 00:15:13,720 Speaker 1: Quantum mechanics says, no, it's it's going to take a 277 00:15:13,760 --> 00:15:16,160 Speaker 1: superposition of all of those paths. It's going to go 278 00:15:16,360 --> 00:15:19,240 Speaker 1: down two or three or four different paths at the 279 00:15:19,280 --> 00:15:21,800 Speaker 1: same time, or as wave function will. But then when 280 00:15:21,840 --> 00:15:24,000 Speaker 1: we measure it at the end, right, we say, all right, 281 00:15:24,200 --> 00:15:26,120 Speaker 1: I'm going to put a device in here. I'm going 282 00:15:26,160 --> 00:15:29,520 Speaker 1: to ask the question, which one did it actually go down? 283 00:15:29,840 --> 00:15:33,240 Speaker 1: I can't measure all those paths, right, I get one answer. 284 00:15:33,440 --> 00:15:35,200 Speaker 1: That's right, you get one answer. If you put a 285 00:15:35,240 --> 00:15:37,760 Speaker 1: detector on one of the paths, then you'll get an 286 00:15:37,760 --> 00:15:40,160 Speaker 1: answer saying you know, yes it went down this path 287 00:15:40,360 --> 00:15:43,920 Speaker 1: or no it didn't. But if instead you set up 288 00:15:44,520 --> 00:15:47,400 Speaker 1: your optical bench, your maze, whatever you want to call it, 289 00:15:47,480 --> 00:15:50,520 Speaker 1: or your double slit experiment so that there's an interference 290 00:15:50,520 --> 00:15:53,680 Speaker 1: pattern on the other side, you will get interference. So 291 00:15:53,720 --> 00:15:58,960 Speaker 1: when you're not asking the question of which way the 292 00:15:58,960 --> 00:16:02,600 Speaker 1: photon went and when it went into your setup, it 293 00:16:02,960 --> 00:16:05,520 Speaker 1: sort of goes down all of those paths and then 294 00:16:05,600 --> 00:16:08,400 Speaker 1: interferes with itself. But if you ask weight which way 295 00:16:08,400 --> 00:16:10,680 Speaker 1: did you go, well, then it says, oh, no, I 296 00:16:10,720 --> 00:16:13,520 Speaker 1: went this way, and then it doesn't interfere with itself. 297 00:16:13,640 --> 00:16:16,480 Speaker 1: And so we know that the wave function does this 298 00:16:16,600 --> 00:16:20,680 Speaker 1: superposition thing having two possible outcomes at the same time 299 00:16:20,760 --> 00:16:24,560 Speaker 1: because we see the interference, that's proof of superposition. But 300 00:16:24,600 --> 00:16:27,600 Speaker 1: then when we try to measure the photon, the superposition 301 00:16:27,720 --> 00:16:30,560 Speaker 1: sneaks away. And for you, is that like the clearest 302 00:16:30,600 --> 00:16:34,200 Speaker 1: encapsulation of this question, this measurement problem, like how the 303 00:16:34,200 --> 00:16:38,240 Speaker 1: wave function goes from having like various quantum mechanical possibilities 304 00:16:38,280 --> 00:16:41,240 Speaker 1: for the paths of a photon to basically picking one. 305 00:16:41,480 --> 00:16:44,400 Speaker 1: How the universe like ends up rolling that die choosing 306 00:16:44,600 --> 00:16:46,640 Speaker 1: this path or that path or the other path. I 307 00:16:46,640 --> 00:16:48,720 Speaker 1: think it's a very clear example of that. The way 308 00:16:48,720 --> 00:16:51,120 Speaker 1: that I usually talk about it is a little different, 309 00:16:51,360 --> 00:16:53,400 Speaker 1: you know, I I say, Okay, this is one example 310 00:16:53,560 --> 00:16:57,680 Speaker 1: of the measurement problem, But in general, the measurement problem 311 00:16:57,800 --> 00:17:01,280 Speaker 1: is more about that sort of undulating property of the 312 00:17:01,320 --> 00:17:03,880 Speaker 1: wave functions that I was talking about before. Right, we 313 00:17:04,040 --> 00:17:08,280 Speaker 1: have this very nice equation, the shroding Er equation. It's 314 00:17:08,440 --> 00:17:10,399 Speaker 1: a law of physics. Right, we think of it as 315 00:17:10,400 --> 00:17:15,680 Speaker 1: a law of nature, and that describes how wave functions wave. Right, 316 00:17:15,720 --> 00:17:20,880 Speaker 1: it says that they always wave sort of smoothly and evenly, 317 00:17:21,000 --> 00:17:23,960 Speaker 1: and you know, they don't make any abrupt transitions. But 318 00:17:25,320 --> 00:17:30,399 Speaker 1: sometimes the shroding Er equation is temporarily suspended. What you 319 00:17:30,480 --> 00:17:33,200 Speaker 1: can't do that you can just pause the laws of physics. 320 00:17:33,200 --> 00:17:35,840 Speaker 1: Sometimes it says, if someone just hits pause on the 321 00:17:35,840 --> 00:17:39,639 Speaker 1: shrodding Er equation and instead you have to use this 322 00:17:39,720 --> 00:17:42,960 Speaker 1: other thing called the Born rule, which says, okay, take 323 00:17:43,000 --> 00:17:47,000 Speaker 1: the wave function and look at all the different possibilities. 324 00:17:47,040 --> 00:17:50,840 Speaker 1: It gives you for the way that your experiment is 325 00:17:50,880 --> 00:17:54,399 Speaker 1: going to turn out, and that gives you the probabilities 326 00:17:54,400 --> 00:17:56,400 Speaker 1: for the different outcomes. That's what the wave function does. 327 00:17:56,760 --> 00:17:59,359 Speaker 1: When you use the Born rule, And then whichever one 328 00:17:59,400 --> 00:18:01,960 Speaker 1: you actually serve, cut out all the other parts of 329 00:18:02,000 --> 00:18:04,640 Speaker 1: the wave function, that's the only one that's left. All 330 00:18:04,640 --> 00:18:08,000 Speaker 1: the others just instantly go to zero and then violates 331 00:18:08,000 --> 00:18:11,000 Speaker 1: the shorting your equation, and that violates the shroting your equation. 332 00:18:11,000 --> 00:18:13,160 Speaker 1: The shrodding your equation doesn't have anything in it like that. 333 00:18:13,600 --> 00:18:16,959 Speaker 1: And then when you stop looking, that's what happens when 334 00:18:17,000 --> 00:18:18,959 Speaker 1: you make a measurement. And then when you stop looking, 335 00:18:19,680 --> 00:18:22,879 Speaker 1: the shorting your equation applies again. And so then the 336 00:18:23,000 --> 00:18:25,639 Speaker 1: question is, okay, well, so if you have these two 337 00:18:25,680 --> 00:18:30,040 Speaker 1: different rules and they contradict each other, then first of all, 338 00:18:30,119 --> 00:18:36,119 Speaker 1: why And second we better be really, really really clear 339 00:18:36,320 --> 00:18:38,600 Speaker 1: about when to use one and when to use the other. 340 00:18:39,920 --> 00:18:42,240 Speaker 1: And this is the collapse of the wave function. And 341 00:18:42,280 --> 00:18:44,720 Speaker 1: so the usual answer to the question when do we 342 00:18:44,840 --> 00:18:46,400 Speaker 1: use one and when do we use the other? When 343 00:18:46,440 --> 00:18:50,400 Speaker 1: does the wave function collapse. The usual answer that is, 344 00:18:50,800 --> 00:18:53,919 Speaker 1: when we make a measurement. And so now the fact 345 00:18:53,960 --> 00:18:58,240 Speaker 1: that the word measurement is kind of vague goes from 346 00:18:59,000 --> 00:19:02,840 Speaker 1: you know, a little troublesome or annoying to a really 347 00:19:03,040 --> 00:19:07,399 Speaker 1: serious problem. Right, So that's a great encapsulation of the 348 00:19:07,520 --> 00:19:10,720 Speaker 1: question we're facing. Like, we have this beautiful equation, the 349 00:19:10,760 --> 00:19:13,920 Speaker 1: shortening your equation that tells us how this wave function 350 00:19:14,040 --> 00:19:17,199 Speaker 1: moves and changes and squishes through the world, and we 351 00:19:17,400 --> 00:19:20,920 Speaker 1: verified it to zillions of degrees of accuracy, except that, 352 00:19:21,000 --> 00:19:24,000 Speaker 1: as you say, sometimes it seems to be ignored and 353 00:19:24,080 --> 00:19:26,960 Speaker 1: sometimes it doesn't seem to apply. And so we have 354 00:19:27,040 --> 00:19:29,520 Speaker 1: this question of like how a wave function goes from 355 00:19:29,520 --> 00:19:32,480 Speaker 1: this smooth under lending property to like collapsing into just 356 00:19:32,640 --> 00:19:35,560 Speaker 1: a point when we make a measurement, what that measurement 357 00:19:35,680 --> 00:19:37,600 Speaker 1: even means. So I want to dig into that in 358 00:19:37,720 --> 00:19:40,240 Speaker 1: much more detail, but first let's take a quick break. 359 00:19:53,080 --> 00:19:55,680 Speaker 1: All right, we're back and we're talking to ask ify 360 00:19:55,680 --> 00:19:58,560 Speaker 1: is this Adam Becker, author of What is real about 361 00:19:58,640 --> 00:20:01,600 Speaker 1: the nature of the quantum a function and what happens 362 00:20:01,640 --> 00:20:03,960 Speaker 1: to it when we look at it? And I have 363 00:20:04,119 --> 00:20:07,000 Speaker 1: this quote that I love from Bell who says either 364 00:20:07,080 --> 00:20:09,600 Speaker 1: the way function as given by the Shorting your equation 365 00:20:09,880 --> 00:20:13,199 Speaker 1: is everything, or it's not right. What do you make 366 00:20:13,240 --> 00:20:15,160 Speaker 1: of that? I see what he's getting that there, and 367 00:20:15,280 --> 00:20:17,920 Speaker 1: I think he's kind of right. I mean, there's got 368 00:20:17,920 --> 00:20:22,000 Speaker 1: to be something more that tells us, Okay, when do 369 00:20:22,119 --> 00:20:24,679 Speaker 1: we apply the shorting our equation and when don't we 370 00:20:25,080 --> 00:20:28,120 Speaker 1: because otherwise, you know, uh, And I think Bell said 371 00:20:28,200 --> 00:20:30,159 Speaker 1: something along these lines as well. We're stuck in this 372 00:20:30,240 --> 00:20:33,000 Speaker 1: situation where these laws of physics that are supposed to 373 00:20:33,000 --> 00:20:36,040 Speaker 1: be fundamental or just kind of hopelessly vague. So we 374 00:20:36,080 --> 00:20:38,359 Speaker 1: have to take the Shortinger equation and the wave function, 375 00:20:38,400 --> 00:20:40,399 Speaker 1: all of which seems wonderful and perfect and beautiful, and 376 00:20:40,680 --> 00:20:42,960 Speaker 1: we love it, and we need to add something else. 377 00:20:43,040 --> 00:20:46,400 Speaker 1: We need to say. Plus, there's this other mechanism that 378 00:20:46,560 --> 00:20:49,399 Speaker 1: makes things collapse. And this, I think is where people 379 00:20:49,400 --> 00:20:54,080 Speaker 1: disagree how to describe this weird combination of ideas and 380 00:20:54,200 --> 00:20:57,440 Speaker 1: sort of a holistic concept. And so first let's talk 381 00:20:57,440 --> 00:21:00,359 Speaker 1: about maybe the most mainstream way to a hack, this 382 00:21:00,600 --> 00:21:03,720 Speaker 1: the most common, the one that people most read about 383 00:21:03,840 --> 00:21:05,879 Speaker 1: in their textbooks. And then I think a lot of 384 00:21:05,880 --> 00:21:09,280 Speaker 1: our listeners referred to which is basically the Copenhagen interpretation, 385 00:21:09,520 --> 00:21:12,200 Speaker 1: where you add something to the shorting your equation that 386 00:21:12,240 --> 00:21:14,639 Speaker 1: makes the wave function collapse when you look at it. 387 00:21:14,800 --> 00:21:16,919 Speaker 1: So how does that actually happen? Like, what do you 388 00:21:16,960 --> 00:21:20,320 Speaker 1: add to your system, you know, mathematically to make that happen. 389 00:21:20,359 --> 00:21:21,960 Speaker 1: You can't just have like a thing that says and 390 00:21:22,160 --> 00:21:24,119 Speaker 1: by the way, if there's a measurement, I mean, doesn't 391 00:21:24,160 --> 00:21:26,760 Speaker 1: everything have to be like you know, written down in 392 00:21:26,840 --> 00:21:28,960 Speaker 1: some sort of equation. The thing is it is just 393 00:21:29,080 --> 00:21:32,200 Speaker 1: kind of added on. They do basically just say, yeah, 394 00:21:32,480 --> 00:21:35,120 Speaker 1: use the shorting your equation, except when a measurement occurs, 395 00:21:35,600 --> 00:21:38,320 Speaker 1: and what a measurement occurs, use this other thing instead. 396 00:21:38,440 --> 00:21:41,160 Speaker 1: Use this collapse roule called the Born rule, named after 397 00:21:41,240 --> 00:21:44,280 Speaker 1: Backs Born, you know, one of the architects of quantum physics. 398 00:21:44,320 --> 00:21:46,480 Speaker 1: And it's just got a completely different mathematical form and 399 00:21:46,520 --> 00:21:49,479 Speaker 1: it's said, you know, it says, okay, you know, like 400 00:21:49,520 --> 00:21:51,760 Speaker 1: I said before, it lets you use the wave function 401 00:21:51,760 --> 00:21:56,400 Speaker 1: to calculate probabilities, and then says, and then the rest 402 00:21:56,440 --> 00:21:58,439 Speaker 1: of the wave function other than the part that you 403 00:21:58,560 --> 00:22:03,240 Speaker 1: saw collapse. So if you're looking for an electron somewhere 404 00:22:03,760 --> 00:22:06,199 Speaker 1: and you've got the wave function of the electron, which is, 405 00:22:06,240 --> 00:22:08,520 Speaker 1: you know, this sort of nice smooth thing that's maybe 406 00:22:08,520 --> 00:22:11,720 Speaker 1: got three or four different peaks. You look for the electron, 407 00:22:11,960 --> 00:22:15,240 Speaker 1: you find it near one of the peaks. The Born 408 00:22:15,400 --> 00:22:18,280 Speaker 1: rule says, okay, well, then what happens to the electron's 409 00:22:18,320 --> 00:22:21,080 Speaker 1: wave function is you know, now it just has one 410 00:22:21,119 --> 00:22:24,359 Speaker 1: extremely narrow peak exactly where you found it, and it 411 00:22:24,400 --> 00:22:28,399 Speaker 1: goes to zero everywhere else. And then when you stop 412 00:22:28,440 --> 00:22:32,399 Speaker 1: looking the shroudding, your equation just applies again, which is 413 00:22:32,440 --> 00:22:34,639 Speaker 1: kind of incredible. And it requires us to sort of 414 00:22:34,800 --> 00:22:37,920 Speaker 1: insert our selves into the equation, right, it needs like 415 00:22:38,240 --> 00:22:41,040 Speaker 1: the measurement part is when we are interacting with this thing. 416 00:22:41,119 --> 00:22:44,240 Speaker 1: And I think the most common question is what counts 417 00:22:44,359 --> 00:22:47,159 Speaker 1: as a measurement? If I put a particle detector in 418 00:22:47,160 --> 00:22:49,880 Speaker 1: there but don't turn it on, does it count? If 419 00:22:49,880 --> 00:22:52,200 Speaker 1: I turn it on but don't connect it to my computer? 420 00:22:52,359 --> 00:22:54,359 Speaker 1: Does it count? If I hook it all up but 421 00:22:54,400 --> 00:22:56,840 Speaker 1: then don't look at the computer screen? Does it count 422 00:22:56,880 --> 00:23:00,600 Speaker 1: as a measurement? And what's special about my part goal detector? 423 00:23:00,920 --> 00:23:04,240 Speaker 1: Isn't that particle constantly interacting with other things? Doesn't that 424 00:23:04,359 --> 00:23:06,960 Speaker 1: count as a measurement? So can we tackle it by 425 00:23:07,040 --> 00:23:10,280 Speaker 1: thinking about so the quantum particles we're using to make 426 00:23:10,280 --> 00:23:12,520 Speaker 1: the measurement, you know, because we don't just like look 427 00:23:12,560 --> 00:23:15,200 Speaker 1: at an electron, right, we like bounce a photon off 428 00:23:15,200 --> 00:23:17,320 Speaker 1: of it or something like that. Yeah, yeah, I mean 429 00:23:17,480 --> 00:23:20,399 Speaker 1: the Copenhagen interpretation sort of lives or dies on on 430 00:23:20,480 --> 00:23:22,520 Speaker 1: what you mean by measurement, right, And so it is 431 00:23:22,560 --> 00:23:24,760 Speaker 1: tempting to say, okay, well, maybe we can get around 432 00:23:24,840 --> 00:23:28,880 Speaker 1: this problem by saying that, you know, the measurement devices 433 00:23:28,920 --> 00:23:31,400 Speaker 1: itself also quantum. But the problem is that if you 434 00:23:31,560 --> 00:23:34,520 Speaker 1: use the shrouding your equation, you know, wave functions and 435 00:23:34,600 --> 00:23:38,520 Speaker 1: the mathematical machinery of quantum mechanics to describe the measurement 436 00:23:38,520 --> 00:23:40,879 Speaker 1: device as well, then all that happens when you make 437 00:23:40,880 --> 00:23:44,440 Speaker 1: a measurement is you go from your measured system in 438 00:23:44,480 --> 00:23:48,879 Speaker 1: a superposition and you're measuring device sort of ready to 439 00:23:48,920 --> 00:23:52,840 Speaker 1: make a measurement, to a state where both the measured 440 00:23:53,200 --> 00:23:57,040 Speaker 1: system and the measuring device are in a superposition. And 441 00:23:57,160 --> 00:23:59,120 Speaker 1: so you know, if you wanted to say, okay, did 442 00:23:59,119 --> 00:24:03,080 Speaker 1: the electron go left or did it go right, and 443 00:24:03,119 --> 00:24:05,640 Speaker 1: then you use your measuring device to answer that question, 444 00:24:06,800 --> 00:24:08,679 Speaker 1: then the shrodding your equation says at the end of 445 00:24:08,680 --> 00:24:11,000 Speaker 1: that measurement. What you're gonna end up with is a 446 00:24:11,160 --> 00:24:14,280 Speaker 1: superposition of the electron went left and the measuring device 447 00:24:14,280 --> 00:24:17,760 Speaker 1: says left, and the electron went right and the measuring 448 00:24:17,800 --> 00:24:20,480 Speaker 1: device says right. So the measuring device has become sort 449 00:24:20,480 --> 00:24:23,760 Speaker 1: of part of the experiment exactly. Yeah, And so that's 450 00:24:23,840 --> 00:24:27,080 Speaker 1: not gonna get you out of it. Eventually, you have to, 451 00:24:27,119 --> 00:24:30,480 Speaker 1: according to the Copenhagen interpretation, you have to say, well, 452 00:24:30,560 --> 00:24:32,840 Speaker 1: then a measurement occurs, and so the shrodding your equation 453 00:24:32,880 --> 00:24:35,680 Speaker 1: doesn't apply anymore, and we have to use the collapse rule, 454 00:24:35,720 --> 00:24:39,679 Speaker 1: the born rule, and so you really need to get 455 00:24:39,720 --> 00:24:43,439 Speaker 1: comfortable with whatever it is that a measurement means, which 456 00:24:44,560 --> 00:24:48,720 Speaker 1: the Copenhagen interpretation is kind of famously vague about. So 457 00:24:48,800 --> 00:24:50,439 Speaker 1: let's break that down a little bit more. So. We 458 00:24:50,480 --> 00:24:53,560 Speaker 1: have our electron and we probe it with the tip 459 00:24:53,640 --> 00:24:56,359 Speaker 1: of some very very narrow tool, and the tip is 460 00:24:56,440 --> 00:24:59,240 Speaker 1: just like a single particle that's interacting with the electron. 461 00:24:59,359 --> 00:25:02,119 Speaker 1: Now we might say, okay, the tools touching the electron, 462 00:25:02,280 --> 00:25:04,679 Speaker 1: so it's being measured, it should collapse. It should just 463 00:25:04,720 --> 00:25:07,560 Speaker 1: collapse right there. But somebody else coming in and looking 464 00:25:07,600 --> 00:25:09,720 Speaker 1: to the experiment. The same way could say no, no no, no, 465 00:25:10,200 --> 00:25:12,880 Speaker 1: I think the system is the electron plus the tip 466 00:25:12,880 --> 00:25:14,840 Speaker 1: of the tool, and the rest of the tool is 467 00:25:14,880 --> 00:25:17,440 Speaker 1: the measuring device. So the tip of the tool plus 468 00:25:17,440 --> 00:25:20,399 Speaker 1: the electron, that's your experiment. That's what you're probing. The 469 00:25:20,400 --> 00:25:24,119 Speaker 1: measurement happens when like the next particle over reads off 470 00:25:24,200 --> 00:25:26,480 Speaker 1: the information from the tip of the tool, And somebody 471 00:25:26,480 --> 00:25:28,640 Speaker 1: else could come along and say no, no, no, I 472 00:25:28,680 --> 00:25:31,760 Speaker 1: think the original electron plus the first two things on 473 00:25:31,800 --> 00:25:34,080 Speaker 1: the tip of the tool are part of the experiment, 474 00:25:34,119 --> 00:25:35,879 Speaker 1: and the rest of it is the measurement. And you 475 00:25:35,880 --> 00:25:38,400 Speaker 1: can just basically do this forever, right all the way 476 00:25:38,400 --> 00:25:40,760 Speaker 1: down the tool, including as many particles as you like, 477 00:25:41,080 --> 00:25:44,560 Speaker 1: or even including the experiment or him or herself. Yeah, 478 00:25:44,560 --> 00:25:47,240 Speaker 1: I mean, quantum mechanics says this weird propensity to just 479 00:25:47,280 --> 00:25:50,000 Speaker 1: sort of generate these sorts of thought experiments like the 480 00:25:50,000 --> 00:25:52,120 Speaker 1: one that you're talking about that sounds like something out 481 00:25:52,119 --> 00:25:56,680 Speaker 1: of like ancient Greek philosophical dialogue or something Zeno's quantum 482 00:25:56,680 --> 00:26:00,720 Speaker 1: experiment exactly. Yeah, I mean there even is a Zene experiment, 483 00:26:00,800 --> 00:26:03,840 Speaker 1: though not that one. But yeah, the problem here is, 484 00:26:04,000 --> 00:26:06,720 Speaker 1: you know, it'd be easy to say, when a measurement occurs. 485 00:26:07,040 --> 00:26:09,919 Speaker 1: If we could say, well, there's a quantum world, and 486 00:26:09,960 --> 00:26:12,920 Speaker 1: then there's a non quantum world, and when a non 487 00:26:13,040 --> 00:26:16,639 Speaker 1: quantum thing interacts with a quantum thing, that's a measurement thing. 488 00:26:16,720 --> 00:26:19,480 Speaker 1: Is nobody believes that anymore because all non quantum things 489 00:26:19,560 --> 00:26:22,879 Speaker 1: are made of quantum things, right exactly. Yeah, we believe 490 00:26:22,960 --> 00:26:26,119 Speaker 1: that the world is made of everything in the world 491 00:26:26,200 --> 00:26:29,640 Speaker 1: is made of molecules, which are made of atoms, which 492 00:26:29,640 --> 00:26:31,919 Speaker 1: are made of sub atomic particles, all of which are 493 00:26:31,960 --> 00:26:34,880 Speaker 1: subject to the loss of quantum mechanics. And quantum mechanics 494 00:26:34,880 --> 00:26:38,160 Speaker 1: doesn't have a real size limit. I mean, certainly there 495 00:26:38,160 --> 00:26:42,080 Speaker 1: are you know, sizes at which some of its features 496 00:26:42,119 --> 00:26:45,920 Speaker 1: are more obvious than others. But in principle, there's no 497 00:26:46,200 --> 00:26:48,400 Speaker 1: limit to the size of a system that you can 498 00:26:48,480 --> 00:26:51,280 Speaker 1: use quantum mechanics to describe. And we believe that the 499 00:26:51,320 --> 00:26:54,960 Speaker 1: whole world is made of particles subject to the laws 500 00:26:54,960 --> 00:26:59,120 Speaker 1: of quantum physics. So yeah, the question becomes if there's 501 00:26:59,119 --> 00:27:01,840 Speaker 1: no border between the quantum world in the non quantum world, 502 00:27:01,920 --> 00:27:04,960 Speaker 1: because the whole world is quantum, then when does a 503 00:27:05,000 --> 00:27:08,720 Speaker 1: measurement occur? Is it when the measurement device touches the object. Well, 504 00:27:09,440 --> 00:27:11,600 Speaker 1: in that case, does that mean that quantum mechanics doesn't 505 00:27:11,600 --> 00:27:14,560 Speaker 1: apply to the measurement device? Okay, Well, maybe it's when 506 00:27:14,680 --> 00:27:17,199 Speaker 1: somebody looks at the measurement device. Maybe it's when I 507 00:27:17,200 --> 00:27:19,160 Speaker 1: look at the measurement device. Okay, But does that mean 508 00:27:19,160 --> 00:27:21,359 Speaker 1: that quantum mechanics doesn't apply to me. I'm made of 509 00:27:21,440 --> 00:27:24,399 Speaker 1: quantum stuff, you know. I'm made of cells, which are 510 00:27:24,400 --> 00:27:26,720 Speaker 1: made of molecules, which are made of sub atomic particles 511 00:27:26,720 --> 00:27:28,560 Speaker 1: and so on. You know, there's no reason to think 512 00:27:28,640 --> 00:27:32,360 Speaker 1: that quantum mechanics doesn't apply to all of the stuff 513 00:27:32,400 --> 00:27:35,440 Speaker 1: in my body and brain. In fact, every time we've 514 00:27:35,520 --> 00:27:38,040 Speaker 1: checked on something like that, we've found that, you know, 515 00:27:38,200 --> 00:27:42,720 Speaker 1: every biochemical process is fully explained by quantum mechanics. All right, 516 00:27:42,760 --> 00:27:45,520 Speaker 1: but there is one wrinkle there, right, Like you are 517 00:27:45,640 --> 00:27:49,120 Speaker 1: different from you know, the ascilloscope or the probe using 518 00:27:49,119 --> 00:27:52,679 Speaker 1: to touch the electron. We think in that you are conscious, right, 519 00:27:52,720 --> 00:27:56,240 Speaker 1: you are a self aware, you're living, thinking, breathing person. 520 00:27:56,400 --> 00:27:58,280 Speaker 1: I don't know about the ascilloscope. I didn't invite the 521 00:27:58,280 --> 00:28:00,639 Speaker 1: acilloscope to be a guest on the podcast to speak 522 00:28:00,680 --> 00:28:02,439 Speaker 1: up for itself. But you know, I think a lot 523 00:28:02,480 --> 00:28:05,480 Speaker 1: of people. Imagine that that might be the moment when 524 00:28:05,480 --> 00:28:08,159 Speaker 1: the measurement happens, when the information like goes through the 525 00:28:08,160 --> 00:28:10,560 Speaker 1: tool and up the computer and into your brain and 526 00:28:10,600 --> 00:28:14,320 Speaker 1: it's like known by a conscious observer. What about that? 527 00:28:14,400 --> 00:28:16,199 Speaker 1: Why can't we use that as a distinction. Well, so 528 00:28:16,240 --> 00:28:19,800 Speaker 1: there's a few issues there, right. One is, you know, 529 00:28:19,880 --> 00:28:22,560 Speaker 1: consciousness is something that we don't understand. Well, what do 530 00:28:22,560 --> 00:28:25,000 Speaker 1: we mean by consciousness? You know, you were sort of 531 00:28:25,000 --> 00:28:26,919 Speaker 1: getting at that before when you were bringing in this 532 00:28:27,080 --> 00:28:29,800 Speaker 1: thought experiment of you know, okay, well, when I look, 533 00:28:29,880 --> 00:28:32,200 Speaker 1: is that the measurement? No? Well, then when you come 534 00:28:32,200 --> 00:28:33,919 Speaker 1: in the room and you look at me, is that 535 00:28:33,960 --> 00:28:37,119 Speaker 1: the measurement. This was put together by this famous physicist 536 00:28:37,280 --> 00:28:41,280 Speaker 1: Eugene Vigner, and it's called the Vigner's friend experiment. And 537 00:28:41,640 --> 00:28:45,200 Speaker 1: I'm conscious, right, my friend is conscious. So maybe the 538 00:28:45,200 --> 00:28:47,080 Speaker 1: measurement happens where I look, or is it when my 539 00:28:47,160 --> 00:28:49,680 Speaker 1: friend looks at me? Or you know, does it have 540 00:28:49,760 --> 00:28:52,000 Speaker 1: to be a human? What if we put a chimp 541 00:28:52,080 --> 00:28:55,480 Speaker 1: in there? Right? What about a dog or a crow? Right? 542 00:28:55,560 --> 00:28:57,840 Speaker 1: Crows are really smart. Hold on, let's break down the 543 00:28:57,880 --> 00:28:59,640 Speaker 1: Vigner's friend experiment, because I think this is where it 544 00:28:59,680 --> 00:29:02,920 Speaker 1: described having like essentially, the idea is, you are doing 545 00:29:02,920 --> 00:29:06,360 Speaker 1: this experiment, you are measuring this electron. You're using a tool, 546 00:29:06,600 --> 00:29:09,160 Speaker 1: and you do the evaluation and you get a number. 547 00:29:09,440 --> 00:29:11,959 Speaker 1: Now I don't know the answer yet, and so in 548 00:29:12,000 --> 00:29:14,080 Speaker 1: some sense I can look at you and say, well, 549 00:29:14,360 --> 00:29:16,520 Speaker 1: you are a part of my tool. Adam, I haven't 550 00:29:16,520 --> 00:29:19,520 Speaker 1: asked you yet what happened, So I don't know the answer. 551 00:29:19,840 --> 00:29:23,600 Speaker 1: So you are still in a quantum superposition of the 552 00:29:23,640 --> 00:29:26,160 Speaker 1: electron went left and the electron went right. So in 553 00:29:26,200 --> 00:29:28,920 Speaker 1: that sense, like a conscious person can be in a 554 00:29:29,000 --> 00:29:32,280 Speaker 1: quantum state, Right, you can have like the wave function 555 00:29:32,360 --> 00:29:36,120 Speaker 1: of Adam Becker having two different possibilities. Yeah, I mean 556 00:29:36,160 --> 00:29:38,640 Speaker 1: that's a problem, right, because that that's the sort of 557 00:29:38,640 --> 00:29:41,080 Speaker 1: thing that feels like you could lead to an infinite regress, 558 00:29:41,800 --> 00:29:44,120 Speaker 1: right you know, Okay, but then you're in a superposition 559 00:29:44,160 --> 00:29:46,240 Speaker 1: until your friend talks to you, and then we start 560 00:29:46,280 --> 00:29:49,720 Speaker 1: having problems like okay, but then, why does everybody agree 561 00:29:49,760 --> 00:29:53,280 Speaker 1: about the outcome of the experiment? And right, what was 562 00:29:53,360 --> 00:29:55,240 Speaker 1: it like to be in a superposition? What did it 563 00:29:55,280 --> 00:29:57,840 Speaker 1: feels What was it like to be in a superposition? Exactly? 564 00:29:57,880 --> 00:29:59,600 Speaker 1: What does it feel like? I don't think that I've 565 00:29:59,600 --> 00:30:01,480 Speaker 1: ever been in two places at once, so that I've 566 00:30:01,480 --> 00:30:04,120 Speaker 1: ever believed that an experiment I felt like I needed 567 00:30:04,160 --> 00:30:07,240 Speaker 1: to be into businesses but exactly and never achieved. Yeah, 568 00:30:07,600 --> 00:30:10,000 Speaker 1: And I certainly don't think that I've ever like, you know, 569 00:30:10,320 --> 00:30:13,400 Speaker 1: looked at the outcome of an experiment and thought, oh, 570 00:30:13,480 --> 00:30:16,720 Speaker 1: that went both of the two mutually contradictory ways that 571 00:30:16,760 --> 00:30:19,000 Speaker 1: it could go. You know, the electron went left and 572 00:30:19,080 --> 00:30:22,160 Speaker 1: it also went right. And I saw the measurement device 573 00:30:22,240 --> 00:30:25,080 Speaker 1: say left and also say right at the same time. 574 00:30:25,160 --> 00:30:28,200 Speaker 1: That's not an experience I remember having. And that kind 575 00:30:28,200 --> 00:30:31,800 Speaker 1: of rules out this notion of consciousness being the threshold, 576 00:30:32,120 --> 00:30:35,200 Speaker 1: because you can put a conscious observer into your experiment 577 00:30:35,440 --> 00:30:38,840 Speaker 1: and still have the wave function not collapse until after 578 00:30:38,880 --> 00:30:41,880 Speaker 1: the conscious observer reports their results. Right, Just at a 579 00:30:41,920 --> 00:30:46,480 Speaker 1: conscious observer observing something doesn't necessarily make the wave function collapse, 580 00:30:46,560 --> 00:30:50,720 Speaker 1: isn't that right? Yeah? With an asterisk tell us about 581 00:30:50,720 --> 00:30:53,040 Speaker 1: the asterisk. Yeah, So, I mean you can set up 582 00:30:53,200 --> 00:30:57,920 Speaker 1: a system where you've got a quantum wave function and superposition, 583 00:30:58,440 --> 00:31:02,000 Speaker 1: and you can sort of verify that it's in a superposition, 584 00:31:02,640 --> 00:31:06,600 Speaker 1: and that verification does not itself lead to the collapse 585 00:31:06,600 --> 00:31:08,320 Speaker 1: of the wave function. Wait, how do you do that? 586 00:31:08,320 --> 00:31:11,000 Speaker 1: How do you verify that? Is that by observing interference? Yeah, 587 00:31:11,040 --> 00:31:13,960 Speaker 1: that's by observing interference. You can see that there's interference. 588 00:31:14,200 --> 00:31:17,160 Speaker 1: But what you can't do, at least what we don't 589 00:31:17,160 --> 00:31:20,360 Speaker 1: have the ability to do right now, is put a 590 00:31:20,560 --> 00:31:24,520 Speaker 1: human in there as part of the system that is 591 00:31:24,600 --> 00:31:29,280 Speaker 1: exhibiting interference. Right, I see, I can't see the various 592 00:31:29,320 --> 00:31:32,959 Speaker 1: modes of Adam interfering with themselves exactly. Yeah, but there 593 00:31:33,000 --> 00:31:36,440 Speaker 1: are other reasons to think that consciousness is probably not 594 00:31:36,640 --> 00:31:38,400 Speaker 1: what's going on here, or if it is, you need 595 00:31:38,480 --> 00:31:41,880 Speaker 1: a really good account of how that's possible. Right, Because 596 00:31:42,280 --> 00:31:45,080 Speaker 1: one of the things that we want to be able 597 00:31:45,080 --> 00:31:47,880 Speaker 1: to use quantum physics to do, and you know, as 598 00:31:48,040 --> 00:31:50,400 Speaker 1: a cosmologists by training, this is near and dear to 599 00:31:50,440 --> 00:31:52,680 Speaker 1: my heart. We want to use quantum physics to describe 600 00:31:52,680 --> 00:31:56,280 Speaker 1: the very early universe. Who want to do quantum cosmology, 601 00:31:56,480 --> 00:31:59,080 Speaker 1: and you know that means talking about things like the 602 00:31:59,120 --> 00:32:03,120 Speaker 1: wave function of universe. And indeed, you know we talk 603 00:32:03,200 --> 00:32:06,080 Speaker 1: about that when we talk about things like, you know, 604 00:32:06,640 --> 00:32:11,760 Speaker 1: patterns in the cosmic microwave background radiation, the oldest light 605 00:32:11,760 --> 00:32:14,200 Speaker 1: in the universe, and echo of the Big Bang. We 606 00:32:14,320 --> 00:32:17,440 Speaker 1: see the imprint of quantum mechanics in the sky. And 607 00:32:17,520 --> 00:32:20,240 Speaker 1: now I am going to almost directly quote John Bell. 608 00:32:20,920 --> 00:32:24,400 Speaker 1: Was the wave function of the universe waiting for billions 609 00:32:24,440 --> 00:32:28,840 Speaker 1: and billions of years for you know, a paramesium to 610 00:32:29,120 --> 00:32:32,600 Speaker 1: arrive and collapse the wave function? Or did it need 611 00:32:32,640 --> 00:32:35,760 Speaker 1: a better qualified observer, you know, someone with a PhD. 612 00:32:36,040 --> 00:32:40,080 Speaker 1: The first PhD collapse, the universe's waiting exactly. Yeah, I 613 00:32:40,120 --> 00:32:43,040 Speaker 1: don't think that that's how that works. I don't think 614 00:32:43,240 --> 00:32:48,400 Speaker 1: that conscious beings are necessary in order for quantum mechanics 615 00:32:48,440 --> 00:32:51,880 Speaker 1: to work. So if the wave function collapses, and we've 616 00:32:51,920 --> 00:32:54,760 Speaker 1: really know the wave function is real and exists outside 617 00:32:55,080 --> 00:32:56,920 Speaker 1: the mind of humans. But if it is real and 618 00:32:57,000 --> 00:32:59,120 Speaker 1: it does collapse, it seems like it must have been 619 00:32:59,160 --> 00:33:02,440 Speaker 1: collapsing for billions of years before we showed up. That's right. 620 00:33:02,520 --> 00:33:04,480 Speaker 1: And if it doesn't collapse, we need to figure out 621 00:33:04,480 --> 00:33:07,440 Speaker 1: why it looks like it does seem important And I 622 00:33:07,480 --> 00:33:10,479 Speaker 1: think that you mentioned something really interesting about how we 623 00:33:10,640 --> 00:33:14,400 Speaker 1: know that asymmetries do exist, right, Like, this question is 624 00:33:14,440 --> 00:33:18,480 Speaker 1: important not just for philosophers, but for like quantum cosmologists. 625 00:33:18,800 --> 00:33:21,160 Speaker 1: How do you go from the beginning of a universe 626 00:33:21,400 --> 00:33:24,800 Speaker 1: where you assume I have a symmetric wave function because 627 00:33:25,000 --> 00:33:28,520 Speaker 1: anything else would be bonkers, and somehow get asymmetries, right, 628 00:33:28,560 --> 00:33:30,920 Speaker 1: how do you get a universe that's not exactly the 629 00:33:30,960 --> 00:33:33,800 Speaker 1: same in every direction? Where do those things come from? 630 00:33:33,800 --> 00:33:38,440 Speaker 1: Those come from quantum fluctuations, which are quantum collapses, right, Yeah, 631 00:33:38,480 --> 00:33:41,200 Speaker 1: that's right. Quantum fluctuations happen when you might have equal 632 00:33:41,240 --> 00:33:43,520 Speaker 1: probabilities to go left or right, but like one of 633 00:33:43,560 --> 00:33:46,280 Speaker 1: them is chosen. The universe does roll a die. And 634 00:33:46,320 --> 00:33:48,840 Speaker 1: so the fact that we exist here and not a 635 00:33:48,880 --> 00:33:51,760 Speaker 1: billion light years to the left is evidence that quantum 636 00:33:51,800 --> 00:33:54,800 Speaker 1: mechanics does fluctuate, that there are these collapses, that these 637 00:33:54,840 --> 00:33:57,600 Speaker 1: things are real somehow, Yeah, exactly, or at least that's 638 00:33:57,600 --> 00:34:00,840 Speaker 1: something like collapse or something that in tates collapse or 639 00:34:00,840 --> 00:34:03,800 Speaker 1: gives the appearance of collapse happens all right, So it 640 00:34:03,840 --> 00:34:07,600 Speaker 1: seems like this Copenhagen interpretation is pretty problematic, right, Like 641 00:34:07,800 --> 00:34:11,239 Speaker 1: there's a basic fundamental unknown in it, like what this 642 00:34:11,400 --> 00:34:13,880 Speaker 1: even means by measurement. We need measurement to get the 643 00:34:13,920 --> 00:34:15,759 Speaker 1: way function to collapse, or to get it to look 644 00:34:15,760 --> 00:34:18,160 Speaker 1: like it collapses, but we don't even really know what 645 00:34:18,200 --> 00:34:20,440 Speaker 1: that means and what triggers it. So how could this 646 00:34:20,520 --> 00:34:25,240 Speaker 1: possibly be the most mainstream, core idea in the most 647 00:34:25,239 --> 00:34:29,400 Speaker 1: fundamental concept in physics. That's a great question, and it 648 00:34:29,520 --> 00:34:32,879 Speaker 1: unfortunately has a very simple answer. The answer is when 649 00:34:32,920 --> 00:34:36,040 Speaker 1: people ask these sorts of questions, they were just sort 650 00:34:36,080 --> 00:34:39,040 Speaker 1: of waved away. It's more complex than that. I wrote 651 00:34:39,080 --> 00:34:42,799 Speaker 1: a whole book about how this happened. Before I did, 652 00:34:42,840 --> 00:34:44,399 Speaker 1: I used to say, well, I could write a book 653 00:34:44,400 --> 00:34:45,960 Speaker 1: about it, and then it turns out that I made 654 00:34:46,000 --> 00:34:49,760 Speaker 1: good onto that way. Function did collapse into a book, 655 00:34:49,920 --> 00:34:52,920 Speaker 1: Yes it did. But yeah, the answer is, you know, 656 00:34:53,160 --> 00:34:56,239 Speaker 1: people ask, well, what do we mean by measurement? We 657 00:34:56,320 --> 00:34:59,520 Speaker 1: have to get more specific about this. How could this 658 00:34:59,600 --> 00:35:05,319 Speaker 1: possly be this vague and ill defined and contradictory And 659 00:35:05,360 --> 00:35:09,000 Speaker 1: the answer that was usually given was it works, so 660 00:35:09,120 --> 00:35:11,759 Speaker 1: don't worry about it. This was sort of summed up 661 00:35:11,840 --> 00:35:16,400 Speaker 1: famously by the physicist David Merman as shut up and calculate. 662 00:35:16,680 --> 00:35:19,920 Speaker 1: That's basically like, don't worry about what it means. It works, 663 00:35:19,960 --> 00:35:23,839 Speaker 1: it predicts our experiments. Who cares. Yeah, don't pay any 664 00:35:23,840 --> 00:35:26,120 Speaker 1: attention to the man behind the curtain, just you know, 665 00:35:26,360 --> 00:35:30,080 Speaker 1: do the calculations, and you'll be able to build most 666 00:35:30,120 --> 00:35:32,520 Speaker 1: of the technology that the modern world is based on, 667 00:35:32,600 --> 00:35:35,080 Speaker 1: which is you know, absolutely true. You know you don't 668 00:35:35,160 --> 00:35:37,760 Speaker 1: need to answer this question in order to do things 669 00:35:37,920 --> 00:35:44,040 Speaker 1: like design semiconductor transistors and build computer chips and lasers 670 00:35:44,040 --> 00:35:47,440 Speaker 1: and l ed s and you know, nuclear power and 671 00:35:47,520 --> 00:35:52,160 Speaker 1: all of the other incredible and you know, awesome in 672 00:35:52,400 --> 00:35:57,600 Speaker 1: the most literal sense technologies that quantum physics has enabled 673 00:35:57,640 --> 00:36:00,400 Speaker 1: over the last century. But science and physics is not 674 00:36:00,680 --> 00:36:05,200 Speaker 1: just about delivering technological improvements for humanity, right, Like, I 675 00:36:05,239 --> 00:36:07,920 Speaker 1: love that all our listeners can hear this podcast on 676 00:36:08,080 --> 00:36:11,520 Speaker 1: various devices enabled by quantum mechanics. But I didn't go 677 00:36:11,560 --> 00:36:14,359 Speaker 1: into physics to like make a better iPhone. I went 678 00:36:14,400 --> 00:36:18,160 Speaker 1: into physics to understand the universe? Right, So doesn't that 679 00:36:18,200 --> 00:36:20,320 Speaker 1: really fly in the face of sort of the core 680 00:36:20,440 --> 00:36:25,840 Speaker 1: mission of the entire discipline to gain some understanding. I 681 00:36:25,920 --> 00:36:31,520 Speaker 1: completely agree with you, but apparently not everyone does. Alright, Well, 682 00:36:31,560 --> 00:36:33,200 Speaker 1: I'm glad we agree on that, and I want to 683 00:36:33,239 --> 00:36:36,480 Speaker 1: dig into some other possibilities, some other ways people have 684 00:36:36,560 --> 00:36:40,000 Speaker 1: attacked this problem, some crazy, totally different ways of thinking 685 00:36:40,000 --> 00:36:42,479 Speaker 1: about what might be real about the universe. But first, 686 00:36:42,520 --> 00:36:57,640 Speaker 1: let's take another break. All right, we're back and we're 687 00:36:57,640 --> 00:37:00,080 Speaker 1: talking to Adam Becker about what is real and if 688 00:37:00,120 --> 00:37:02,839 Speaker 1: anything is real and if the universe can possibly make 689 00:37:02,880 --> 00:37:05,640 Speaker 1: sense at all, and are we even here? And we've 690 00:37:05,680 --> 00:37:08,480 Speaker 1: been talking about the wave function and how the Copenhagen 691 00:37:08,520 --> 00:37:12,440 Speaker 1: the mainstream interpretation of quantum mechanics has a basic problem 692 00:37:12,480 --> 00:37:15,239 Speaker 1: in it and that it can't define what a measurement is. 693 00:37:15,360 --> 00:37:18,720 Speaker 1: But a measurement is essential to making the theory work, 694 00:37:18,920 --> 00:37:21,040 Speaker 1: so it can't be the only idea that's out there. 695 00:37:21,320 --> 00:37:24,840 Speaker 1: Surely people have thought of some other approaches. And so 696 00:37:25,040 --> 00:37:27,400 Speaker 1: if you're a listener to Sean Carroll, for example, you 697 00:37:27,520 --> 00:37:30,120 Speaker 1: probably heard him as a big proponent of this ever 698 00:37:30,120 --> 00:37:34,480 Speaker 1: already in many worlds interpretation. So how does a many 699 00:37:34,560 --> 00:37:38,560 Speaker 1: worlds interpretation, How does manufacturing billions and billions of branching 700 00:37:38,640 --> 00:37:42,279 Speaker 1: universes solve this measurement problem? Or does it? That's a 701 00:37:42,320 --> 00:37:45,160 Speaker 1: great question I want to say before I answer that 702 00:37:45,200 --> 00:37:49,400 Speaker 1: this is something that I get a lot of email 703 00:37:49,760 --> 00:37:52,279 Speaker 1: and people asking me about it. Back when you know, 704 00:37:52,360 --> 00:37:55,000 Speaker 1: in person, back when you know we could do things 705 00:37:55,000 --> 00:37:58,439 Speaker 1: in person. For whatever reason, a lot of people came 706 00:37:58,480 --> 00:38:02,040 Speaker 1: away from my book thinking that I agree with Sean Carroll, 707 00:38:02,600 --> 00:38:06,840 Speaker 1: and I like Sean Shan is a great guy. Yeah, 708 00:38:07,000 --> 00:38:10,640 Speaker 1: but I think that his position is a reasonable one. 709 00:38:11,400 --> 00:38:14,640 Speaker 1: But I don't think that it's the only reasonable one. 710 00:38:14,920 --> 00:38:18,120 Speaker 1: And I think that I am not here as a 711 00:38:18,120 --> 00:38:23,719 Speaker 1: shill of big many worlds, just a shill of big quantum. 712 00:38:23,840 --> 00:38:26,560 Speaker 1: Many world is already big. You don't say big in front. 713 00:38:26,719 --> 00:38:29,520 Speaker 1: Yeah that's true. Now, many worlds, I think is pretty 714 00:38:29,600 --> 00:38:34,640 Speaker 1: clearly the next most popular interpretation after this sort of jumble. 715 00:38:34,760 --> 00:38:37,839 Speaker 1: That is the Copenhagen interpretation. All right, to breakdown for us, 716 00:38:37,880 --> 00:38:40,280 Speaker 1: what is the many worlds interpretation? So the many world's 717 00:38:40,320 --> 00:38:43,120 Speaker 1: interpretation gets out of the measurement problem by saying, oh, yeah, 718 00:38:43,280 --> 00:38:46,359 Speaker 1: collapse doesn't happen. It just sort of looks like it does. 719 00:38:46,760 --> 00:38:51,000 Speaker 1: It takes the sort of infectious property of superposition, where 720 00:38:51,040 --> 00:38:55,080 Speaker 1: you know, if a measurement device measures something that's in superposition, 721 00:38:55,120 --> 00:38:58,400 Speaker 1: then it will go into superposition. It takes that property 722 00:38:58,560 --> 00:39:01,560 Speaker 1: and sort of embraces it wholeheartedly and turns it into 723 00:39:01,560 --> 00:39:05,759 Speaker 1: a strength. It says, okay, well, collapse never happens. The 724 00:39:05,880 --> 00:39:09,359 Speaker 1: Born rule is, you know, not a fundamental thing in 725 00:39:10,080 --> 00:39:13,839 Speaker 1: nature that describes what's actually happening in the world. It's 726 00:39:13,880 --> 00:39:17,640 Speaker 1: just something we need to make predictions. And in reality, 727 00:39:17,800 --> 00:39:21,800 Speaker 1: the Schrodinger equation or you know, the relativistic extensions thereof 728 00:39:21,960 --> 00:39:26,200 Speaker 1: always apply, and so wave functions always just evolved smoothly, 729 00:39:26,280 --> 00:39:30,000 Speaker 1: which means that when you make a measurement of an 730 00:39:30,000 --> 00:39:33,240 Speaker 1: electron or something in a superposition. You know, the classic 731 00:39:33,280 --> 00:39:36,000 Speaker 1: example here is Schrodinger's cat. You set it up with 732 00:39:36,080 --> 00:39:38,840 Speaker 1: a quantum device where you know, if it goes one way, 733 00:39:39,280 --> 00:39:41,239 Speaker 1: the cat lives, and if it goes the other way, 734 00:39:41,239 --> 00:39:45,160 Speaker 1: the cat dies. So when you open the box, you 735 00:39:45,560 --> 00:39:49,239 Speaker 1: find a cat that is both dead and alive. It's 736 00:39:49,239 --> 00:39:52,360 Speaker 1: in a superposition of dead and alive. And then you know, 737 00:39:52,440 --> 00:39:55,720 Speaker 1: in the process of opening the box, you enter into 738 00:39:55,760 --> 00:40:00,280 Speaker 1: a superposition yourself of seeing a dead cat and seeing 739 00:40:00,280 --> 00:40:02,880 Speaker 1: a living cat. And then someone else comes in the 740 00:40:02,960 --> 00:40:05,319 Speaker 1: room and they enter a superposition of you know, seeing 741 00:40:05,400 --> 00:40:08,759 Speaker 1: you crying over this dead cat and seeing you, you know, 742 00:40:09,080 --> 00:40:11,920 Speaker 1: playing with the living cat and so on, and this 743 00:40:12,080 --> 00:40:16,600 Speaker 1: just sort of spreads out into the universe. So you're saying, 744 00:40:16,600 --> 00:40:19,360 Speaker 1: the way function never actually collapses and picks one of 745 00:40:19,360 --> 00:40:23,360 Speaker 1: these branches. It just keep branching, and we are only 746 00:40:23,520 --> 00:40:25,880 Speaker 1: in one of those branches, which is why it looks 747 00:40:25,960 --> 00:40:29,200 Speaker 1: like it collapses sort of. The question of where we 748 00:40:29,280 --> 00:40:32,920 Speaker 1: are in the theory is definitely something that's contentious, But 749 00:40:33,040 --> 00:40:36,120 Speaker 1: I think that what Sean would say, Well, I don't 750 00:40:36,120 --> 00:40:38,560 Speaker 1: want to put words into Sean's mouth. If I put 751 00:40:38,560 --> 00:40:40,640 Speaker 1: on my many world's hat and say, Okay, I'm gonna 752 00:40:40,640 --> 00:40:42,840 Speaker 1: pretend to be a real advocate of many worlds, I 753 00:40:42,880 --> 00:40:47,200 Speaker 1: would say, no, we're in both branches. But once we split, 754 00:40:47,600 --> 00:40:51,480 Speaker 1: a quantum process called decoherence ensures that the two branches, 755 00:40:52,280 --> 00:40:55,600 Speaker 1: you know, once they involve large objects made of many 756 00:40:55,680 --> 00:40:59,560 Speaker 1: quantum particles, can't interfere or communicate with each other in 757 00:40:59,600 --> 00:41:03,840 Speaker 1: any way a very very quickly, and so we split. 758 00:41:04,880 --> 00:41:08,799 Speaker 1: And so you know, if you ask one of the 759 00:41:09,000 --> 00:41:13,680 Speaker 1: copies of you that is in either branch, hey, how 760 00:41:13,680 --> 00:41:16,040 Speaker 1: many cats do you see? How many outcomes do you 761 00:41:16,080 --> 00:41:18,879 Speaker 1: see for this cat? Both of them would say, oh, 762 00:41:18,920 --> 00:41:22,399 Speaker 1: I only see one outcome. They just disagree about what 763 00:41:22,480 --> 00:41:25,040 Speaker 1: that outcome is. And so this is why it's called 764 00:41:25,120 --> 00:41:29,080 Speaker 1: many worlds, because it imagines that multiple versions of the 765 00:41:29,200 --> 00:41:33,640 Speaker 1: universe are existing decoherently, that they've decohere from each other, 766 00:41:34,080 --> 00:41:36,920 Speaker 1: and they're all out there. They're real, but they're sort 767 00:41:36,960 --> 00:41:40,240 Speaker 1: of like not accessible to us anymore because we're only 768 00:41:40,239 --> 00:41:42,960 Speaker 1: in one branch of the way of function. Yeah, we're 769 00:41:43,000 --> 00:41:45,640 Speaker 1: this copy of ourselves is only in this branch, but 770 00:41:45,680 --> 00:41:48,680 Speaker 1: there are other near identical copies in all of the 771 00:41:48,680 --> 00:41:50,600 Speaker 1: other branches. And so I was trying to lead you 772 00:41:50,680 --> 00:41:52,560 Speaker 1: down the garden path there, I think to my major 773 00:41:52,600 --> 00:41:55,879 Speaker 1: objection to the many worlds interpretation, which is like, why 774 00:41:55,960 --> 00:41:59,040 Speaker 1: are we in this one? Because, as you say, like 775 00:41:59,200 --> 00:42:01,799 Speaker 1: there's a copy of me in all of those universes 776 00:42:02,000 --> 00:42:05,400 Speaker 1: that have observed every possible outcome of the Schrodinger's box experiment. 777 00:42:05,680 --> 00:42:08,120 Speaker 1: But still I'm this one, and I know that in 778 00:42:08,160 --> 00:42:10,960 Speaker 1: the other universe, the other me thinks that it's that one, 779 00:42:11,160 --> 00:42:13,840 Speaker 1: and that's fine, But why is it in that universe? 780 00:42:13,840 --> 00:42:16,400 Speaker 1: And I'm in this universe? Like there is still something 781 00:42:16,480 --> 00:42:20,600 Speaker 1: special about this universe because I'm in it, right, Well, 782 00:42:20,920 --> 00:42:23,960 Speaker 1: you know, your copy in the other universe where the 783 00:42:24,040 --> 00:42:27,080 Speaker 1: cat died would say the same thing. I know, but 784 00:42:27,160 --> 00:42:30,120 Speaker 1: it also has a reasonable objection, Right, there is still 785 00:42:30,239 --> 00:42:33,160 Speaker 1: something different about this universe because I'm in it, And 786 00:42:33,160 --> 00:42:36,040 Speaker 1: there's something different about that universe because it's in that one. 787 00:42:36,120 --> 00:42:38,719 Speaker 1: It seems to me like does not really avoid this 788 00:42:38,840 --> 00:42:42,280 Speaker 1: problem because it still takes one universe to be special 789 00:42:42,320 --> 00:42:44,239 Speaker 1: in some sense, because this is the only one that 790 00:42:44,400 --> 00:42:47,239 Speaker 1: I'm experiencing anyway. What are your concerns about the many 791 00:42:47,320 --> 00:42:51,280 Speaker 1: world interpretation. Well, the classic concern about it is that 792 00:42:51,520 --> 00:42:54,680 Speaker 1: you still actually need the Born rule, right, because quantum 793 00:42:54,719 --> 00:42:58,759 Speaker 1: mechanics doesn't issue forth certain predictions. It doesn't say this 794 00:42:58,880 --> 00:43:03,080 Speaker 1: is you know, definitely what's going to happen. It says 795 00:43:03,080 --> 00:43:05,880 Speaker 1: that sometimes, But most of the time, the predictions of 796 00:43:05,960 --> 00:43:08,400 Speaker 1: quantum mechanics come in the form of probabilities that says, well, 797 00:43:08,400 --> 00:43:10,239 Speaker 1: there's a twenty percent chance that this is going to happen, 798 00:43:10,280 --> 00:43:12,240 Speaker 1: in a thirty percent chance that's gonna happen, a fifty 799 00:43:12,280 --> 00:43:14,239 Speaker 1: percent chance that that's going to happen, and you know, 800 00:43:14,239 --> 00:43:17,680 Speaker 1: those are the possible outcomes. But in a world where 801 00:43:17,680 --> 00:43:20,880 Speaker 1: the shroting Your equation always applies, well, the shroting Your 802 00:43:20,920 --> 00:43:24,560 Speaker 1: equation has no probability in it. The Shrotinger equation is 803 00:43:24,680 --> 00:43:29,160 Speaker 1: actually like Newton's physics, and that it's completely deterministic. You know, 804 00:43:29,239 --> 00:43:32,080 Speaker 1: when you ask, uh, many worlds person, well, what's going 805 00:43:32,120 --> 00:43:35,080 Speaker 1: to happen? When you open the box. They'd say, well, 806 00:43:35,120 --> 00:43:39,440 Speaker 1: with one d percent probability, I will split into two copies, 807 00:43:39,520 --> 00:43:41,080 Speaker 1: one of which we'll see a living cat and the 808 00:43:41,120 --> 00:43:44,399 Speaker 1: other we'll see a dead cat. That's definitely what's going 809 00:43:44,440 --> 00:43:47,480 Speaker 1: to happen. And so then you know the next question, 810 00:43:47,560 --> 00:43:49,520 Speaker 1: which is, you know, what's the probability that you're going 811 00:43:49,600 --> 00:43:51,600 Speaker 1: to see a living cat because I don't want to 812 00:43:51,719 --> 00:43:55,000 Speaker 1: get a cat. The answer to that has to be, well, 813 00:43:55,040 --> 00:43:56,960 Speaker 1: you need to use the Born rule. You need to 814 00:43:57,040 --> 00:44:00,120 Speaker 1: use this collapse rule, because that collapse rule is how 815 00:44:00,200 --> 00:44:02,919 Speaker 1: we get predictions out of quantum physics. It's what makes 816 00:44:02,960 --> 00:44:07,359 Speaker 1: it so phenomenally accurate and powerful. And so you need 817 00:44:07,400 --> 00:44:11,720 Speaker 1: to figure out, Okay, how do we introduce probability into 818 00:44:11,760 --> 00:44:15,480 Speaker 1: a theory in which literally anything that can happen does happen. 819 00:44:15,880 --> 00:44:19,920 Speaker 1: That's a little thorny and one way of going about it. 820 00:44:19,960 --> 00:44:22,239 Speaker 1: And this is actually a position that I know for 821 00:44:22,320 --> 00:44:25,000 Speaker 1: sure Sean holds. So now I am gonna like do 822 00:44:25,080 --> 00:44:29,440 Speaker 1: my best Sean Carroll impression. Sean says that, well, the 823 00:44:29,480 --> 00:44:34,560 Speaker 1: probability comes from basically exactly your concern that we don't 824 00:44:34,600 --> 00:44:40,200 Speaker 1: know where in this branching multiverse of worlds we are located, 825 00:44:41,000 --> 00:44:45,160 Speaker 1: and so we have uncertainty about where we are, and 826 00:44:45,200 --> 00:44:48,040 Speaker 1: that uncertainty is where the probabilities come from. When we 827 00:44:48,080 --> 00:44:50,439 Speaker 1: do the experiment and we see an outcome, what we're 828 00:44:50,440 --> 00:44:55,279 Speaker 1: actually doing is learning where in the many worlds we are. 829 00:44:56,520 --> 00:45:02,000 Speaker 1: And then you can look at the structure of this 830 00:45:02,120 --> 00:45:06,080 Speaker 1: multiverse and sort of derive the Born rule from it. 831 00:45:06,239 --> 00:45:08,400 Speaker 1: You can say, okay, well, this is the right way 832 00:45:08,800 --> 00:45:12,520 Speaker 1: to answer questions about probabilities. So the problem with the 833 00:45:12,520 --> 00:45:15,439 Speaker 1: many worlds interpretation, then, is that it keeps the wave 834 00:45:15,480 --> 00:45:18,960 Speaker 1: functions sort of too long. The wave function itself doesn't 835 00:45:18,960 --> 00:45:21,600 Speaker 1: actually make predictions, as you say, it can be used 836 00:45:21,640 --> 00:45:24,080 Speaker 1: to make predictions, but if you just keep the wave 837 00:45:24,120 --> 00:45:27,000 Speaker 1: function going forever, then how do you actually predict the 838 00:45:27,040 --> 00:45:30,520 Speaker 1: outcome of an experiment? All right, that's fascinating. Yeah, you 839 00:45:30,560 --> 00:45:32,360 Speaker 1: need to answer that. And I want to be clear 840 00:45:33,000 --> 00:45:36,359 Speaker 1: the many advocates of many worlds generally have answers to that, 841 00:45:36,680 --> 00:45:40,960 Speaker 1: although I don't think that there's consensus around one single 842 00:45:41,080 --> 00:45:43,879 Speaker 1: answer to that among all of the many advocates of 843 00:45:44,680 --> 00:45:47,520 Speaker 1: you know, this kind of interpretation. They're aware of this 844 00:45:47,640 --> 00:45:50,080 Speaker 1: problem and they've addressed it, and they have answers to it. 845 00:45:50,160 --> 00:45:52,920 Speaker 1: So the question isn't you know how do you answer it? 846 00:45:53,040 --> 00:45:56,080 Speaker 1: The question is does one or several of the answers 847 00:45:56,120 --> 00:46:00,720 Speaker 1: that have been provided work? And that is an open question. Awesome, 848 00:46:01,080 --> 00:46:03,200 Speaker 1: And so before we wrap up, I want to touch 849 00:46:03,239 --> 00:46:06,400 Speaker 1: on a couple of other ideas. So those totally different 850 00:46:06,400 --> 00:46:10,279 Speaker 1: directions people are taking about attacking this deep question about 851 00:46:10,320 --> 00:46:13,200 Speaker 1: the meaning of the wave function and what measurement means. 852 00:46:13,560 --> 00:46:16,560 Speaker 1: And one of my favorites is this hidden variable theory 853 00:46:16,640 --> 00:46:19,640 Speaker 1: or the categories of theories called hidden variable theories, because 854 00:46:19,680 --> 00:46:23,200 Speaker 1: when I was learning about quantum mechanics, I remember thinking like, well, sure, 855 00:46:23,280 --> 00:46:25,520 Speaker 1: but how do we know it's not like just actually 856 00:46:25,560 --> 00:46:28,719 Speaker 1: determined by something we're not aware of? You know? It 857 00:46:28,840 --> 00:46:32,800 Speaker 1: feels like maybe our lack of information, this uncertainty in 858 00:46:32,800 --> 00:46:36,239 Speaker 1: the universe doesn't just come from inherent uncertainty, but it 859 00:46:36,280 --> 00:46:38,880 Speaker 1: just comes from like our not seeing the full picture. 860 00:46:38,960 --> 00:46:41,800 Speaker 1: So maybe there's like something going on behind the scenes 861 00:46:41,840 --> 00:46:44,640 Speaker 1: that's controlling everything. How do we know that's not the case? 862 00:46:44,640 --> 00:46:46,239 Speaker 1: How do we know that it's not just like more 863 00:46:46,320 --> 00:46:49,880 Speaker 1: to the universe that makes it actually deterministic. That's a 864 00:46:49,920 --> 00:46:52,319 Speaker 1: great question, and you're a really good company there as 865 00:46:52,320 --> 00:46:55,239 Speaker 1: I'm sure you know. You know, Albert Einstein basically had 866 00:46:55,400 --> 00:46:57,799 Speaker 1: exactly the same question. You know, it's a myth that 867 00:46:57,880 --> 00:47:00,400 Speaker 1: he never accepted quantum physics. He knew that it worked, 868 00:47:00,880 --> 00:47:03,759 Speaker 1: and he he fully accepted that it worked. He just 869 00:47:03,760 --> 00:47:06,480 Speaker 1: thought it couldn't be the whole story for basically the 870 00:47:06,520 --> 00:47:11,239 Speaker 1: same reason that you're giving. And in particular, he was 871 00:47:11,440 --> 00:47:16,240 Speaker 1: very unhappy about the idea that things depended on observation 872 00:47:16,320 --> 00:47:19,399 Speaker 1: and that you couldn't talk about what was happening when 873 00:47:19,440 --> 00:47:22,279 Speaker 1: you weren't looking. He thought that this was, you know, 874 00:47:22,760 --> 00:47:25,239 Speaker 1: as you were saying, just kind of avoiding the whole 875 00:47:25,239 --> 00:47:28,080 Speaker 1: point of science. Science is about figuring out what's in 876 00:47:28,080 --> 00:47:30,040 Speaker 1: the world and how it works. And he was also 877 00:47:30,200 --> 00:47:35,279 Speaker 1: really concerned about the possibility introduced in quantum physics for 878 00:47:35,320 --> 00:47:38,160 Speaker 1: what he called spooky action at a distance, these long 879 00:47:38,560 --> 00:47:45,480 Speaker 1: distance connections between objects, and that is actually directly related, 880 00:47:45,560 --> 00:47:48,520 Speaker 1: as it turns out, to the answer to your question. 881 00:47:48,640 --> 00:47:51,040 Speaker 1: You know, the question, is there's something going on that 882 00:47:51,120 --> 00:47:55,719 Speaker 1: we don't know about some you know, hidden properties what 883 00:47:55,760 --> 00:47:59,680 Speaker 1: we usually call hidden variables of these particles that you 884 00:47:59,680 --> 00:48:01,799 Speaker 1: know to termine their behavior, and we just don't know 885 00:48:01,920 --> 00:48:04,439 Speaker 1: what they are. And that's where the uncertainty comes from. 886 00:48:04,640 --> 00:48:10,480 Speaker 1: The answer to that that we know is yes, it's possible, 887 00:48:10,960 --> 00:48:14,040 Speaker 1: but you have to pay a price. The price is 888 00:48:14,120 --> 00:48:18,400 Speaker 1: spooky action at a distance, and that was proven by 889 00:48:18,600 --> 00:48:23,600 Speaker 1: experiments that were done to test a theorem by John Bell. 890 00:48:23,840 --> 00:48:27,160 Speaker 1: So we can have a super deterministic universe, but it 891 00:48:27,239 --> 00:48:30,400 Speaker 1: can't be local. We can't also have like everything we 892 00:48:30,520 --> 00:48:33,239 Speaker 1: determined about what's happening right here. So yeah, I gotta 893 00:48:33,320 --> 00:48:37,680 Speaker 1: be like really pedantic and nitpicky. There is actually a 894 00:48:37,719 --> 00:48:43,440 Speaker 1: class of interpretations called super determinism, and that's something else. 895 00:48:44,920 --> 00:48:48,960 Speaker 1: But yes, we can have a deterministic universe. We can 896 00:48:49,080 --> 00:48:52,360 Speaker 1: have hidden variables that determine everything that's going on. But 897 00:48:52,560 --> 00:48:55,359 Speaker 1: the price we have to pay is that, you know, 898 00:48:55,480 --> 00:48:59,440 Speaker 1: things that happen right here can instantaneously influenced stuff that 899 00:48:59,480 --> 00:49:04,480 Speaker 1: happens arbitrarily far away, and do so in a way 900 00:49:04,520 --> 00:49:09,759 Speaker 1: that provably can't be used to send anything information or 901 00:49:09,880 --> 00:49:12,080 Speaker 1: material faster than the speed of light. All right, So 902 00:49:12,160 --> 00:49:16,080 Speaker 1: that's super deterministic with a lower case as and two words, Yes, 903 00:49:16,160 --> 00:49:20,440 Speaker 1: what's super determinism single where where the capital as is 904 00:49:20,440 --> 00:49:23,600 Speaker 1: that superman is determining the outcome of all these quantum experiments. 905 00:49:23,600 --> 00:49:28,800 Speaker 1: Super Determinism is the idea of like a hardcore clockwork universe. 906 00:49:28,800 --> 00:49:32,440 Speaker 1: It's this idea that, oh, we can explain the outcome 907 00:49:32,520 --> 00:49:37,840 Speaker 1: of these Bell experiments without sacrificing locality and without you know, 908 00:49:37,840 --> 00:49:40,640 Speaker 1: without sacrificing the idea that you know, instantaneous action at 909 00:49:40,680 --> 00:49:43,520 Speaker 1: a distance can't happen. We can also do it without 910 00:49:43,560 --> 00:49:48,960 Speaker 1: sacrificing the idea of determinism. But to do that instead, 911 00:49:49,160 --> 00:49:53,280 Speaker 1: we have to say, oh, at the beginning of time, 912 00:49:53,640 --> 00:49:58,000 Speaker 1: in the Big Bang, a whole bunch of really fine 913 00:49:58,080 --> 00:50:03,239 Speaker 1: grained information was encoded into every particle in the universe 914 00:50:03,440 --> 00:50:07,560 Speaker 1: about the outcomes of those experiments, those Bell experiments that 915 00:50:07,560 --> 00:50:11,520 Speaker 1: would be conducted, you know, thirteen point eight billion years 916 00:50:11,600 --> 00:50:16,920 Speaker 1: later um, that would arrange for them to turn out 917 00:50:16,960 --> 00:50:19,880 Speaker 1: in a way that would trick us into thinking that, 918 00:50:20,040 --> 00:50:22,640 Speaker 1: you know, the universe was nonlocal. So we do these 919 00:50:22,680 --> 00:50:25,759 Speaker 1: experiments and they seem to suggest the universe is nonlocal, 920 00:50:26,040 --> 00:50:29,480 Speaker 1: but that's just because they've been cleverly arranged fourteen billion 921 00:50:29,560 --> 00:50:33,720 Speaker 1: years ago to look that way. Yeah, that's super determinism. Yeah, 922 00:50:33,760 --> 00:50:37,800 Speaker 1: that's super nuts. Yeah, I'm not super sympathetic to supers, 923 00:50:39,040 --> 00:50:41,040 Speaker 1: but you know, all these ideas are kind of crazy. 924 00:50:41,080 --> 00:50:43,640 Speaker 1: All of them have things you might object to. I guess. 925 00:50:43,680 --> 00:50:45,799 Speaker 1: In the end, the question I have for you is 926 00:50:46,080 --> 00:50:48,279 Speaker 1: are we going to figure this out? Or how could 927 00:50:48,400 --> 00:50:51,720 Speaker 1: we figure this out? Are there experiments we can do 928 00:50:52,080 --> 00:50:54,680 Speaker 1: to figure out which of these things are real? Or 929 00:50:54,840 --> 00:50:58,160 Speaker 1: is it just going to rely on philosophers smoking bananappeals 930 00:50:58,320 --> 00:51:01,440 Speaker 1: and organism in their minds? Yeah? I know this is 931 00:51:01,480 --> 00:51:04,960 Speaker 1: a great question. So the answer depends on what you 932 00:51:05,000 --> 00:51:07,799 Speaker 1: mean by is there an experiment that we can do? Right? So, 933 00:51:08,000 --> 00:51:12,200 Speaker 1: if you're asking, is there an experiment that we can 934 00:51:12,440 --> 00:51:17,840 Speaker 1: do to figure out which of these different interpretations of 935 00:51:17,960 --> 00:51:21,600 Speaker 1: quantum physics is the right way to think about quantum 936 00:51:21,600 --> 00:51:28,120 Speaker 1: physics right now? The answer to that is no, because 937 00:51:28,320 --> 00:51:32,920 Speaker 1: they all give the same or almost all give almost 938 00:51:32,920 --> 00:51:36,640 Speaker 1: all the same outcomes for all experiments provably. I mean, 939 00:51:36,680 --> 00:51:39,560 Speaker 1: there are some proposals for solving the measurement problem that 940 00:51:39,600 --> 00:51:43,520 Speaker 1: aren't just new interpretations but are actually completely different theories. 941 00:51:43,560 --> 00:51:46,480 Speaker 1: There's a class of theories called objective collapse theories that 942 00:51:46,600 --> 00:51:49,879 Speaker 1: modify the shrouding R equation. Those can be tested, so yes, 943 00:51:49,960 --> 00:51:52,120 Speaker 1: some of them can just be directly tested, and those 944 00:51:52,120 --> 00:51:54,560 Speaker 1: tests are sort of ongoing. But for most of these, 945 00:51:54,680 --> 00:51:58,479 Speaker 1: like many worlds, interpretation or the best known and most 946 00:51:58,520 --> 00:52:02,480 Speaker 1: developed of the hidden ables interpretations called Bonian mechanics or 947 00:52:02,560 --> 00:52:04,680 Speaker 1: depoid bone theory or pilot wave theory, has a few 948 00:52:04,680 --> 00:52:07,439 Speaker 1: different names, which is, you know, nonlocal. And they think 949 00:52:07,480 --> 00:52:09,600 Speaker 1: that that's like a good thing about the theory, and 950 00:52:09,680 --> 00:52:11,719 Speaker 1: that's a whole other story. I'm not saying that to 951 00:52:11,760 --> 00:52:14,080 Speaker 1: disparage them. I understand why they say that, and I 952 00:52:14,160 --> 00:52:16,399 Speaker 1: think that that's also a reasonable position. But the point 953 00:52:16,480 --> 00:52:19,560 Speaker 1: is those two and you know, many of the other 954 00:52:19,600 --> 00:52:22,879 Speaker 1: interpretations of quantum mechanics are just that their interpretations, they 955 00:52:23,000 --> 00:52:27,360 Speaker 1: all provably give rise to exactly the same outcomes in 956 00:52:27,480 --> 00:52:29,560 Speaker 1: all of these experiments. And so if you ask them, well, 957 00:52:29,560 --> 00:52:32,640 Speaker 1: what's the experimental evidence, they'd say, all experimental evidence for 958 00:52:32,719 --> 00:52:36,440 Speaker 1: quantum physics, you know, is experimental evidence for this interpretation 959 00:52:36,480 --> 00:52:39,600 Speaker 1: as well. So in that sense, no, there's no experimental 960 00:52:39,640 --> 00:52:42,040 Speaker 1: way to distinguish between them. Doesn't that mean we just 961 00:52:42,080 --> 00:52:44,560 Speaker 1: haven't been clever enough. I mean, if we have seven 962 00:52:44,600 --> 00:52:47,520 Speaker 1: theories that all fit the data, it just means we 963 00:52:47,560 --> 00:52:49,640 Speaker 1: need to come up with a more clever experiment that 964 00:52:49,719 --> 00:52:53,040 Speaker 1: can distinguish between those seven theories right. Otherwise you have 965 00:52:53,120 --> 00:52:56,720 Speaker 1: to accept the possibility that there could be multiple theories 966 00:52:56,760 --> 00:53:00,200 Speaker 1: of physics that work perfectly to describe our universe, in 967 00:53:00,200 --> 00:53:03,040 Speaker 1: which case, like the whole project of physics of coming 968 00:53:03,120 --> 00:53:05,840 Speaker 1: up with a unique idea to describe the universe and 969 00:53:05,840 --> 00:53:08,920 Speaker 1: then interpreting what that idea means is sort of cast 970 00:53:08,960 --> 00:53:11,400 Speaker 1: into doubt. I have some good news and some bad news. 971 00:53:14,480 --> 00:53:16,759 Speaker 1: Let's start with the bad news. The bad news is 972 00:53:17,480 --> 00:53:21,319 Speaker 1: all of these theories provably give rise to exactly the 973 00:53:21,360 --> 00:53:26,640 Speaker 1: same mathematics and provably you know, spit out the same 974 00:53:26,920 --> 00:53:32,440 Speaker 1: results for the same experiments. And in fact, you can 975 00:53:32,560 --> 00:53:37,719 Speaker 1: even prove that given the mathematical structure of any scientific 976 00:53:37,760 --> 00:53:42,400 Speaker 1: theory you could ever devise, there is an infinite number 977 00:53:42,400 --> 00:53:46,000 Speaker 1: of interpretations that you could come up with to you know, 978 00:53:46,160 --> 00:53:49,680 Speaker 1: explain what's going on in that theory. So that does 979 00:53:49,760 --> 00:53:53,319 Speaker 1: sound bad from the perspective of you know, physics and 980 00:53:53,400 --> 00:53:55,520 Speaker 1: the project of trying to understand what's going on in 981 00:53:55,560 --> 00:54:00,280 Speaker 1: the world. The good news is that's not at actually 982 00:54:00,360 --> 00:54:03,720 Speaker 1: how physics works. You know, we don't sit down and say, okay, well, 983 00:54:03,760 --> 00:54:06,680 Speaker 1: there's an infinite space of possible theories for the mathematical 984 00:54:06,719 --> 00:54:09,520 Speaker 1: structure that we devised, and so now we need to 985 00:54:09,520 --> 00:54:11,960 Speaker 1: try to narrow that infinite space. That's not how we 986 00:54:12,040 --> 00:54:14,520 Speaker 1: do physics. How we do physics and how we do 987 00:54:14,560 --> 00:54:17,000 Speaker 1: science more generally, as we say, okay, well, look, we 988 00:54:17,080 --> 00:54:19,680 Speaker 1: have these ideas about how nature works. And these ideas 989 00:54:19,680 --> 00:54:21,560 Speaker 1: come from a variety of places. They come from the 990 00:54:21,600 --> 00:54:25,480 Speaker 1: results of experiments. They come from older theories that we 991 00:54:25,560 --> 00:54:27,719 Speaker 1: have that worked and now seem to be breaking down. 992 00:54:28,120 --> 00:54:32,160 Speaker 1: They come from new theoretical ideas that we've been kicking 993 00:54:32,200 --> 00:54:36,560 Speaker 1: around because we like them. And they come from you know, 994 00:54:36,760 --> 00:54:41,840 Speaker 1: preconceived cultural and social norms, and you know, mythology and 995 00:54:41,840 --> 00:54:44,600 Speaker 1: and storytelling and whatnot. You know, just ideas that we 996 00:54:44,640 --> 00:54:47,560 Speaker 1: have about the world. And all of that goes into 997 00:54:47,600 --> 00:54:52,360 Speaker 1: the process of judgment that is made when new theories 998 00:54:52,400 --> 00:54:55,240 Speaker 1: are developed and choices are made about how to interpret 999 00:54:55,239 --> 00:54:57,760 Speaker 1: those theories. It sounds like you're talking about a neta 1000 00:54:57,920 --> 00:55:01,200 Speaker 1: level of measurement where we're like measuring the ability and 1001 00:55:01,360 --> 00:55:05,759 Speaker 1: experiment to satisfy our need to understand the universe exactly. Yeah, 1002 00:55:05,800 --> 00:55:09,840 Speaker 1: that's not wrong. But the thing is that's actually good 1003 00:55:09,840 --> 00:55:14,480 Speaker 1: news when it comes to the question of interpreting quantum 1004 00:55:14,480 --> 00:55:16,839 Speaker 1: physics and finding out which, if any of these, is 1005 00:55:16,880 --> 00:55:20,560 Speaker 1: the best way to think about quantum physics, because we 1006 00:55:20,600 --> 00:55:24,200 Speaker 1: know we're not done. You know, the one thing aside 1007 00:55:24,239 --> 00:55:26,160 Speaker 1: from the success of quantum physics that I think that 1008 00:55:26,239 --> 00:55:30,120 Speaker 1: you could get everyone in you know, the world of 1009 00:55:30,200 --> 00:55:32,600 Speaker 1: quantum foundations, in the world of physics more generally to 1010 00:55:32,680 --> 00:55:37,879 Speaker 1: agree upon, is that we are not done in our 1011 00:55:38,040 --> 00:55:41,319 Speaker 1: search for the fundamental laws of the universe. We know, 1012 00:55:41,960 --> 00:55:45,200 Speaker 1: if nothing else, that we have not found a way 1013 00:55:45,239 --> 00:55:48,600 Speaker 1: to get our best theory of gravity general relativity to 1014 00:55:48,800 --> 00:55:53,400 Speaker 1: work with our best theories of you know, quantum physics, 1015 00:55:53,719 --> 00:55:55,640 Speaker 1: you know, quantum field theory and the standard model of 1016 00:55:55,680 --> 00:55:58,760 Speaker 1: particle physics. And we also know that that standard model 1017 00:55:58,880 --> 00:56:01,720 Speaker 1: is not just missing gravity, but is also missing things 1018 00:56:01,719 --> 00:56:04,400 Speaker 1: like dark energy and dark matter. So we know that 1019 00:56:04,480 --> 00:56:07,200 Speaker 1: we're not done, and so that means we're still on 1020 00:56:07,239 --> 00:56:10,560 Speaker 1: the hunt for new theories. And one of the things 1021 00:56:11,480 --> 00:56:14,879 Speaker 1: that goes into the mix when coming up with new 1022 00:56:14,960 --> 00:56:19,480 Speaker 1: theories is the interpretations of old theories. So the way 1023 00:56:19,520 --> 00:56:24,319 Speaker 1: we think about quantum physics now can influence the hunt 1024 00:56:24,440 --> 00:56:27,640 Speaker 1: for the next theory that will go beyond our current 1025 00:56:27,719 --> 00:56:31,719 Speaker 1: understanding of physics, and it also goes backwards. If and 1026 00:56:31,800 --> 00:56:36,120 Speaker 1: when we come up with that theory, it will probably 1027 00:56:36,200 --> 00:56:40,879 Speaker 1: suggest to us an experiment that can be conducted that 1028 00:56:40,960 --> 00:56:44,760 Speaker 1: would distinguish between some or all of the existing options 1029 00:56:44,760 --> 00:56:48,120 Speaker 1: on the table for interpreting quantum mechanics. Yeah. I have 1030 00:56:48,280 --> 00:56:51,360 Speaker 1: faith in the future of experimental physics to get us 1031 00:56:51,440 --> 00:56:53,439 Speaker 1: out of this jam by coming up with a clever 1032 00:56:53,560 --> 00:56:58,080 Speaker 1: new experiment. Yeah, we should all right. Well, that's wonderful. 1033 00:56:58,120 --> 00:57:00,680 Speaker 1: Thank you very much, Adam. I think it's been a 1034 00:57:00,719 --> 00:57:04,520 Speaker 1: delightful journey through the problems and possible solutions to the 1035 00:57:04,600 --> 00:57:07,560 Speaker 1: questions at the heart of quantum mechanics. And I'm glad 1036 00:57:07,600 --> 00:57:09,400 Speaker 1: that there's still a lot of work to do because 1037 00:57:09,520 --> 00:57:13,160 Speaker 1: us quantum physicists will still have a job. So thanks 1038 00:57:13,160 --> 00:57:15,399 Speaker 1: Adam very much for joining us and for explaining these 1039 00:57:15,440 --> 00:57:17,880 Speaker 1: things so clearly. Before we go, do you want to 1040 00:57:17,880 --> 00:57:20,600 Speaker 1: tell our listeners about any upcoming projects you have or 1041 00:57:20,640 --> 00:57:22,720 Speaker 1: at places they can find you other than your excellent 1042 00:57:22,760 --> 00:57:25,480 Speaker 1: book What Is Real? First, I just want to encourage 1043 00:57:25,480 --> 00:57:29,880 Speaker 1: people go find my book if you like hearing about 1044 00:57:30,000 --> 00:57:32,960 Speaker 1: these things. I like talking about them, but I like 1045 00:57:33,040 --> 00:57:35,680 Speaker 1: writing about them even more. And there's you know, three 1046 00:57:35,720 --> 00:57:39,000 Speaker 1: hundred pages of it available wherever fine books are sold. 1047 00:57:39,040 --> 00:57:41,200 Speaker 1: If you want to find me on Twitter or really 1048 00:57:41,200 --> 00:57:45,840 Speaker 1: almost anywhere else, my Twitter name and online handle is 1049 00:57:46,000 --> 00:57:50,520 Speaker 1: freelance Astro, so i'm you know, on most social media 1050 00:57:50,600 --> 00:57:54,000 Speaker 1: under that name, and my website is freelance astro dot 1051 00:57:54,000 --> 00:57:57,280 Speaker 1: com and you can find links to my latest work there. 1052 00:57:57,520 --> 00:58:00,520 Speaker 1: And yeah, aside from that, I am working on another 1053 00:58:00,600 --> 00:58:04,000 Speaker 1: book about science and Silicon Valley, but it will not 1054 00:58:04,080 --> 00:58:07,480 Speaker 1: be out for another couple of years, still in the 1055 00:58:07,600 --> 00:58:10,560 Speaker 1: very early stages. But yeah, if this sort of thing 1056 00:58:10,640 --> 00:58:13,080 Speaker 1: is interesting to you, please have a look at my book. 1057 00:58:13,160 --> 00:58:15,000 Speaker 1: All right, Well, thanks again for coming on, and I 1058 00:58:15,040 --> 00:58:18,320 Speaker 1: hope your next book collapses into a very readable pile 1059 00:58:18,480 --> 00:58:20,680 Speaker 1: just like the first one. Thank you best of luck 1060 00:58:20,720 --> 00:58:23,200 Speaker 1: with that, and thanks again for coming on. Thanks thanks 1061 00:58:23,200 --> 00:58:24,840 Speaker 1: for having me. This was a lot of fun, and 1062 00:58:24,920 --> 00:58:27,160 Speaker 1: thanks to all your listeners for coming along on another 1063 00:58:27,440 --> 00:58:30,880 Speaker 1: ride of curiosity where we investigate what the universe actually 1064 00:58:30,960 --> 00:58:33,920 Speaker 1: means and try to explain it all to you. Tune 1065 00:58:33,960 --> 00:58:44,280 Speaker 1: in next time. Thanks for listening, and remember that Daniel 1066 00:58:44,320 --> 00:58:46,840 Speaker 1: and Jorge explained the universe. Is a production of I 1067 00:58:47,080 --> 00:58:50,480 Speaker 1: Heart Radio or more podcast for my Heart Radio, visit 1068 00:58:50,520 --> 00:58:54,040 Speaker 1: the I Heart radio, app, Apple podcasts, or wherever you 1069 00:58:54,120 --> 00:59:01,200 Speaker 1: listen to your favorite shows. No.