1 00:00:02,880 --> 00:00:04,880 Speaker 1: Hey everyone, it's Daniel with a quick note about my 2 00:00:04,920 --> 00:00:08,600 Speaker 1: new book, which is out now, Do Aliens Speak Physics. 3 00:00:08,600 --> 00:00:10,600 Speaker 1: It's all about how easy or hard it might be 4 00:00:10,680 --> 00:00:13,880 Speaker 1: to talk to arriving aliens about physics. I think it's 5 00:00:14,040 --> 00:00:16,040 Speaker 1: right up your alley, but you don't have to trust me. 6 00:00:16,400 --> 00:00:19,560 Speaker 1: Here's what Shamus Blackly, creator of the Xbox, said about 7 00:00:19,600 --> 00:00:22,439 Speaker 1: it quote. You should buy this book if you don't 8 00:00:22,440 --> 00:00:24,720 Speaker 1: buy it for the charming, smart Vundy prose. Buy it 9 00:00:24,760 --> 00:00:27,920 Speaker 1: for the lovely and poignant illustrations. Buy it for the wonderful, 10 00:00:27,960 --> 00:00:30,680 Speaker 1: imaginative daydreams about how we might meet aliens and what 11 00:00:30,720 --> 00:00:33,879 Speaker 1: they'd be like. Buy it because they will gently accidentally 12 00:00:34,000 --> 00:00:37,000 Speaker 1: educate you by the history of language, translation, decryption, and 13 00:00:37,040 --> 00:00:41,200 Speaker 1: the cultural impact of the writing and transmitting ideas. Not enough, 14 00:00:41,440 --> 00:00:44,600 Speaker 1: buy it for the thoughtful, clear, and genuinely entertaining grand 15 00:00:44,600 --> 00:00:47,839 Speaker 1: tour of the fundamentals of math, physics, and the universality 16 00:00:47,880 --> 00:00:51,040 Speaker 1: of consciousness. You won't go wrong, So please consider picking 17 00:00:51,080 --> 00:01:04,800 Speaker 1: up a copy of Do Aliens Speak Physics. The goal 18 00:01:04,840 --> 00:01:07,240 Speaker 1: of science is to make sense of the world, to 19 00:01:07,480 --> 00:01:11,000 Speaker 1: unravel the laws that controls it and translate them into 20 00:01:11,040 --> 00:01:14,800 Speaker 1: something that makes sense to us. But there's no guarantee 21 00:01:14,800 --> 00:01:17,759 Speaker 1: that the universe runs on rules that we can understand. 22 00:01:18,120 --> 00:01:21,240 Speaker 1: What if our intuition, built in a slow and large 23 00:01:21,360 --> 00:01:25,640 Speaker 1: environment doesn't equip us with ways of understanding that can 24 00:01:25,720 --> 00:01:28,840 Speaker 1: be mapped to the quantum world. One of the trickiest 25 00:01:28,880 --> 00:01:32,480 Speaker 1: elements of quantum mechanics is its strange randomness. We like 26 00:01:32,600 --> 00:01:36,160 Speaker 1: to think that the universe follows rules that determine what happens, 27 00:01:36,560 --> 00:01:40,039 Speaker 1: that at any moment there is a true story of reality. 28 00:01:40,640 --> 00:01:44,680 Speaker 1: But quantum mechanics says no, there are only probabilities until 29 00:01:44,720 --> 00:01:48,400 Speaker 1: you look and that a random one is selected. And 30 00:01:48,440 --> 00:01:51,760 Speaker 1: if you have two quantum objects whose fates are intertwined, 31 00:01:52,040 --> 00:01:55,120 Speaker 1: who have to coordinate their outcomes to follow some rule, 32 00:01:55,600 --> 00:01:59,960 Speaker 1: then those outcomes are somehow determined together, even across back 33 00:02:00,320 --> 00:02:05,480 Speaker 1: distances of space instantaneously. How does that make sense? Today, 34 00:02:05,520 --> 00:02:08,200 Speaker 1: we're going to do a deep dive into quantum entanglement 35 00:02:08,240 --> 00:02:12,639 Speaker 1: and try to untangle some misconceptions. Welcome to Daniel and 36 00:02:12,760 --> 00:02:15,440 Speaker 1: Kelly's Extraordinary quantum Universe. 37 00:02:28,680 --> 00:02:31,680 Speaker 2: Hello, I'm Kelly leader Smith. I study parasites and space, 38 00:02:31,720 --> 00:02:34,120 Speaker 2: and I'm excited that I'm going to have all of 39 00:02:34,160 --> 00:02:37,560 Speaker 2: my confusion about entangled particles cleared up today, I will 40 00:02:37,600 --> 00:02:38,240 Speaker 2: be an expert. 41 00:02:39,720 --> 00:02:42,920 Speaker 1: Hi. I'm Daniel. I'm a particle physicist, and often I 42 00:02:42,960 --> 00:02:45,480 Speaker 1: feel like a superposition of many Daniels. 43 00:02:46,120 --> 00:02:50,440 Speaker 2: Okay, all right, psychologist Kelly, I'm putting on my psychology hat. 44 00:02:50,720 --> 00:02:52,040 Speaker 2: What does that mean, Daniel? 45 00:02:53,320 --> 00:02:55,280 Speaker 1: Well, you know, the simplest way to think about it is, 46 00:02:55,320 --> 00:02:58,040 Speaker 1: we have so many roles in our lives, right. You know, 47 00:02:58,200 --> 00:03:01,560 Speaker 1: you're a spouse, you're a parent, you're a scientist, you're 48 00:03:01,600 --> 00:03:05,119 Speaker 1: an author, you're a citizen. Sometimes we feel like such 49 00:03:05,160 --> 00:03:08,079 Speaker 1: different roles with conflicting needs. It almost feels like you're 50 00:03:08,080 --> 00:03:11,119 Speaker 1: a different person in each context. Didn't you get that way? 51 00:03:11,240 --> 00:03:11,440 Speaker 3: Yeah? 52 00:03:11,639 --> 00:03:17,040 Speaker 2: Yeah, you forgot goat herder, but goose lord and goose lord, 53 00:03:17,639 --> 00:03:21,079 Speaker 2: Lady of the goose, the geese, lady of the geese. Yeah, 54 00:03:21,120 --> 00:03:24,519 Speaker 2: we just named our geese Jacques and Francine Gusto. We're 55 00:03:24,600 --> 00:03:25,680 Speaker 2: very excited about that. 56 00:03:27,000 --> 00:03:29,080 Speaker 1: And some of this is reflected in my CV, and 57 00:03:29,080 --> 00:03:30,720 Speaker 1: so I have to put you on the spot, Kelly, 58 00:03:30,840 --> 00:03:31,880 Speaker 1: did you do your homework? 59 00:03:32,560 --> 00:03:32,720 Speaker 4: Did? 60 00:03:32,760 --> 00:03:34,839 Speaker 2: I didn't look at your CV? No? 61 00:03:35,120 --> 00:03:37,440 Speaker 1: Oh my god, you didn't look at my CV? Well, 62 00:03:37,520 --> 00:03:40,320 Speaker 1: the blank stare I just got fakes? You would be amazed. 63 00:03:40,520 --> 00:03:41,520 Speaker 2: I can't believe you're. 64 00:03:41,400 --> 00:03:42,200 Speaker 1: Asking me minute. 65 00:03:44,520 --> 00:03:47,000 Speaker 2: I still have dreams about forgetting to do my homework. 66 00:03:47,320 --> 00:03:49,840 Speaker 1: Oh well, here you go. Yeah, and giving you a 67 00:03:49,920 --> 00:03:51,800 Speaker 1: zero on this one, but you know to turn it 68 00:03:51,800 --> 00:03:54,160 Speaker 1: in late. Maybe we can give you some some partial credit. 69 00:03:54,240 --> 00:03:56,720 Speaker 2: I didn't think you actually expected me to go find 70 00:03:56,760 --> 00:03:59,200 Speaker 2: your CV. How about you send it to me in 71 00:03:59,240 --> 00:03:59,760 Speaker 2: an email? 72 00:04:00,240 --> 00:04:02,920 Speaker 1: Okay, okay, it's not that hard. Just google me. 73 00:04:03,000 --> 00:04:05,480 Speaker 2: All right, all right, I'll hear. I'm gonna make myself 74 00:04:05,480 --> 00:04:11,840 Speaker 2: a note after I heard the goats, I'll find Daniel CV. 75 00:04:14,920 --> 00:04:18,360 Speaker 1: I'm second in importance to the goats. I feel so honored. 76 00:04:18,560 --> 00:04:21,400 Speaker 2: Well, I might also take the geese for a swim first. 77 00:04:24,240 --> 00:04:25,880 Speaker 1: All right, Well, many of you out there also have 78 00:04:26,000 --> 00:04:29,039 Speaker 1: multiple roles in your lives. You are podcast listeners. You 79 00:04:29,080 --> 00:04:31,680 Speaker 1: are curious about science, but you are also nurses and 80 00:04:31,760 --> 00:04:34,960 Speaker 1: teachers and firefighters and bankers and all sorts of stuff. 81 00:04:35,000 --> 00:04:37,400 Speaker 1: We love hearing from you, so right in, tell us 82 00:04:37,400 --> 00:04:40,280 Speaker 1: who you are, what you do, and how this podcast 83 00:04:40,400 --> 00:04:42,000 Speaker 1: superimposes on your life. 84 00:04:42,640 --> 00:04:46,159 Speaker 2: Oh man, I never get tired of physics puns. 85 00:04:46,960 --> 00:04:50,720 Speaker 1: Maybe, and today we're going to hear about something I 86 00:04:50,800 --> 00:04:53,719 Speaker 1: hear about a lot from listeners who really want to 87 00:04:53,839 --> 00:04:58,760 Speaker 1: understand one of the weirdest, most confounding, yet most revealing 88 00:04:58,839 --> 00:05:03,000 Speaker 1: things we've learned about the universe, which is quantum entanglement 89 00:05:03,080 --> 00:05:04,440 Speaker 1: and how it all works. 90 00:05:05,120 --> 00:05:08,920 Speaker 2: This is a super confusing topic, I think, and it's 91 00:05:08,960 --> 00:05:11,280 Speaker 2: one of those topics where I have to admit and 92 00:05:11,279 --> 00:05:13,520 Speaker 2: I think I've said this on the show before I 93 00:05:13,600 --> 00:05:16,400 Speaker 2: hear about it, and I think physicists are missing something. 94 00:05:17,920 --> 00:05:20,880 Speaker 2: Can't this can't be true. But I'm sure by the 95 00:05:20,960 --> 00:05:22,680 Speaker 2: end of the episode you're going to convince me this 96 00:05:22,720 --> 00:05:25,760 Speaker 2: is definitely true and we should give more money to 97 00:05:25,880 --> 00:05:27,520 Speaker 2: science to figure it out better. 98 00:05:27,880 --> 00:05:30,800 Speaker 1: Well, you're right, actually, because the story we're going to 99 00:05:30,839 --> 00:05:34,800 Speaker 1: tell the end is about physicists misinterpreting their own results 100 00:05:35,320 --> 00:05:39,360 Speaker 1: and misunderstanding it and propagating that misunderstanding for decades until 101 00:05:39,360 --> 00:05:42,760 Speaker 1: we understood really what these experiments were telling us. So 102 00:05:43,240 --> 00:05:46,040 Speaker 1: even physicists at the top level we're talking about von 103 00:05:46,120 --> 00:05:51,680 Speaker 1: Neumann and his colleagues misunderstood or misrepresented what these experiments mean. 104 00:05:52,080 --> 00:05:53,360 Speaker 1: So it's not easy. 105 00:05:53,600 --> 00:05:57,160 Speaker 2: I'm thrilled to report that that has never happened in biology. 106 00:06:00,080 --> 00:06:00,200 Speaker 5: Right. 107 00:06:00,240 --> 00:06:03,560 Speaker 1: Well, before we dig into quantum entanglement, I wanted to 108 00:06:03,600 --> 00:06:05,480 Speaker 1: know what people out there thought about it and what 109 00:06:05,520 --> 00:06:08,680 Speaker 1: they found confusing about it to make sure that all 110 00:06:08,720 --> 00:06:11,520 Speaker 1: of the quantum itches out there got scratched. So I 111 00:06:11,560 --> 00:06:13,720 Speaker 1: reached out to our group of volunteers, which you are 112 00:06:13,960 --> 00:06:16,840 Speaker 1: very welcome to join. Write to us to questions at 113 00:06:16,920 --> 00:06:20,080 Speaker 1: Danielankelly dot org and we'll add you to the Volunteer 114 00:06:20,200 --> 00:06:23,400 Speaker 1: Question Answering Corps. Here is what people had to say 115 00:06:23,400 --> 00:06:27,320 Speaker 1: when I asked them, what's the most confusing thing about quantum? 116 00:06:27,520 --> 00:06:28,800 Speaker 1: Entangled particles? 117 00:06:28,960 --> 00:06:30,839 Speaker 2: And I'm going to add my voice to the chorus. 118 00:06:31,400 --> 00:06:31,880 Speaker 2: All of it. 119 00:06:35,480 --> 00:06:38,400 Speaker 6: Particles are entangled because they're a part of a system 120 00:06:38,400 --> 00:06:40,680 Speaker 6: and that entangles them. And then they go off and 121 00:06:40,680 --> 00:06:43,440 Speaker 6: become part of another system, and so they're entangled in 122 00:06:43,480 --> 00:06:47,680 Speaker 6: another system. It's just how they would move from being 123 00:06:47,839 --> 00:06:52,480 Speaker 6: entangled to one to another. It just seems arbitrary how 124 00:06:52,480 --> 00:06:53,200 Speaker 6: they would do that. 125 00:06:53,400 --> 00:06:55,839 Speaker 7: Speed, which deemed for life from troubles. 126 00:06:55,920 --> 00:06:59,320 Speaker 3: Like, what's so special about two particles being formed at 127 00:06:59,320 --> 00:07:01,440 Speaker 3: the same place at the same time, so that like 128 00:07:02,040 --> 00:07:03,760 Speaker 3: they're entangled. 129 00:07:03,960 --> 00:07:08,120 Speaker 1: But probably the thing that is most confused is that 130 00:07:08,320 --> 00:07:11,560 Speaker 1: it is a method for faster than light communication. 131 00:07:12,240 --> 00:07:15,840 Speaker 8: I think it's confusing that if there's a collapse of 132 00:07:16,360 --> 00:07:22,160 Speaker 8: quantum state on one particle, there's an instantaneous corresponding collapse 133 00:07:22,160 --> 00:07:26,720 Speaker 8: on the other particle. But regardless of distance, this isn't 134 00:07:26,760 --> 00:07:30,559 Speaker 8: a transmission of information faster than the speed of light. 135 00:07:31,200 --> 00:07:34,440 Speaker 7: The most confusing part of quantum intangled particles is how 136 00:07:34,520 --> 00:07:37,800 Speaker 7: we keep their states from collapsing to figure out they 137 00:07:37,800 --> 00:07:39,160 Speaker 7: were entangled in the first place. 138 00:07:39,520 --> 00:07:43,960 Speaker 1: I heard something recently that said entanglement could be non 139 00:07:44,040 --> 00:07:46,280 Speaker 1: traversible wormholes between particles. 140 00:07:46,360 --> 00:07:50,200 Speaker 8: I'd say, that's that's really confusing. How does the universe 141 00:07:50,320 --> 00:07:54,480 Speaker 8: get the information to the other particle when one of 142 00:07:54,560 --> 00:07:57,320 Speaker 8: the two is measured, it's just mind boggling. 143 00:07:57,760 --> 00:08:01,000 Speaker 5: Well, for me, it's that there's no information transferred. So 144 00:08:01,080 --> 00:08:03,480 Speaker 5: if you got an up and a down particle and 145 00:08:03,600 --> 00:08:06,160 Speaker 5: you separate them, one turns out to be up, the 146 00:08:06,200 --> 00:08:08,360 Speaker 5: other one has to be down. But it's got to 147 00:08:08,400 --> 00:08:09,560 Speaker 5: be more complicated than that. 148 00:08:10,040 --> 00:08:13,000 Speaker 7: I can't think of anything about them that is not confusing. 149 00:08:13,640 --> 00:08:15,680 Speaker 1: Well, this is just about what I expect that you know, 150 00:08:15,840 --> 00:08:19,040 Speaker 1: good deep questions about how do we know the universe 151 00:08:19,120 --> 00:08:22,080 Speaker 1: really is random? How do we know it wasn't actually 152 00:08:22,080 --> 00:08:25,119 Speaker 1: determined in advance? Somehow how does this whole thing happen 153 00:08:25,160 --> 00:08:28,600 Speaker 1: across great distances? Can you use this to communicate faster 154 00:08:28,680 --> 00:08:31,240 Speaker 1: than light? It is all very confusing. 155 00:08:30,960 --> 00:08:33,360 Speaker 2: And we did chat on a previous episode about whether 156 00:08:33,400 --> 00:08:35,480 Speaker 2: or not you can use it to communicate faster than light, 157 00:08:35,760 --> 00:08:38,560 Speaker 2: and I remember that the answer is no, that's right, 158 00:08:38,640 --> 00:08:41,600 Speaker 2: that's right. But you know, let's remind every one of 159 00:08:41,640 --> 00:08:46,679 Speaker 2: all of the details, and like all truly exciting explanations, 160 00:08:46,679 --> 00:08:47,960 Speaker 2: we're going to start with definition. 161 00:08:48,960 --> 00:08:52,480 Speaker 1: So hey, if you want to be crisp and really 162 00:08:52,480 --> 00:08:55,439 Speaker 1: explain stuff, you got to use these words that mean something. 163 00:08:55,480 --> 00:08:57,600 Speaker 1: And so we have to agree on what words mean, 164 00:08:57,679 --> 00:09:01,280 Speaker 1: which is why, yes, every important philisold of conversation starts 165 00:09:01,320 --> 00:09:05,400 Speaker 1: with like, what do you mean by science anyway? Because 166 00:09:05,400 --> 00:09:07,439 Speaker 1: words are fuzzy and slippery, right. 167 00:09:07,440 --> 00:09:10,480 Speaker 2: Yeah, no, I do. I do absolutely agree it is important. 168 00:09:10,520 --> 00:09:14,280 Speaker 2: So let's start by defining random, which I know is 169 00:09:14,320 --> 00:09:17,600 Speaker 2: a term that can get many statistics people very angry. 170 00:09:17,640 --> 00:09:20,520 Speaker 2: If you say I randomly picked blah and you weren't 171 00:09:20,559 --> 00:09:24,160 Speaker 2: actually random. You can see that they're like the blood 172 00:09:24,200 --> 00:09:26,600 Speaker 2: is boiling, and they'll like steam is about to come 173 00:09:26,640 --> 00:09:29,719 Speaker 2: out of their ears, And so why are statisticians mad 174 00:09:29,760 --> 00:09:32,040 Speaker 2: at me? When I say I pick something randomly and 175 00:09:32,160 --> 00:09:33,360 Speaker 2: it wasn't really random. 176 00:09:33,480 --> 00:09:36,160 Speaker 1: Yeah, And teenagers have their own definition of random, you know, 177 00:09:36,240 --> 00:09:39,680 Speaker 1: like some random on the internet. Well, it's not really random, 178 00:09:39,760 --> 00:09:41,760 Speaker 1: is it? But the teenagers don't want to hear that. 179 00:09:42,040 --> 00:09:44,280 Speaker 2: What teenagers don't want to hear what their parents have 180 00:09:44,360 --> 00:09:45,920 Speaker 2: to say when we want to correct them and make 181 00:09:45,920 --> 00:09:47,880 Speaker 2: sure they're accurate. Impossible? 182 00:09:48,120 --> 00:09:54,400 Speaker 1: Actually answer right. So let's distinguish true randomness from our 183 00:09:54,440 --> 00:09:58,040 Speaker 1: typical experience of things we call random. So, for example, 184 00:09:58,200 --> 00:10:01,480 Speaker 1: we use like dice or coin when we need a 185 00:10:01,559 --> 00:10:03,600 Speaker 1: random number. You're playing a game, you need a number 186 00:10:03,600 --> 00:10:06,240 Speaker 1: between one and six. You don't want to chosen in advance. 187 00:10:06,320 --> 00:10:08,640 Speaker 1: You roll a die, you have to decide who gets 188 00:10:08,679 --> 00:10:11,120 Speaker 1: the last couple of ice cream. You flip a coin. Right, 189 00:10:11,760 --> 00:10:15,840 Speaker 1: But these processes are not truly random. They're actually chaotic 190 00:10:16,440 --> 00:10:20,280 Speaker 1: and they're not random because they're deterministic, which means that 191 00:10:20,320 --> 00:10:23,240 Speaker 1: the initial conditions exactly how you roll the die or 192 00:10:23,280 --> 00:10:26,920 Speaker 1: exactly how you flip the coin determines the outcome. If 193 00:10:26,960 --> 00:10:29,360 Speaker 1: you did it exactly the same way twice, you would 194 00:10:29,440 --> 00:10:33,320 Speaker 1: get exactly the same answer. Because it's following laws of physics. 195 00:10:33,360 --> 00:10:38,360 Speaker 9: Classical physics which are deterministic, but you know you're never 196 00:10:38,640 --> 00:10:41,800 Speaker 9: you really doing it the same way twice, so why 197 00:10:42,200 --> 00:10:43,520 Speaker 9: why are you being this way? 198 00:10:46,320 --> 00:10:49,199 Speaker 1: And you're right, that's almost impossible to do, maybe literally 199 00:10:49,240 --> 00:10:52,120 Speaker 1: impossible to do, which is why it's a useful stand 200 00:10:52,160 --> 00:10:56,800 Speaker 1: in for random processes. When you need something unpredictable, then 201 00:10:56,840 --> 00:10:59,520 Speaker 1: you use a chaotic process, and that's what these are 202 00:11:00,360 --> 00:11:03,040 Speaker 1: and dice. They are chaotic. They are very very difficult 203 00:11:03,080 --> 00:11:06,199 Speaker 1: to predict because they're very sensitive to the initial conditions. 204 00:11:06,520 --> 00:11:08,600 Speaker 1: We have these points and these edges and the die 205 00:11:08,760 --> 00:11:11,920 Speaker 1: so that if you toss it slightly differently, it has 206 00:11:11,960 --> 00:11:13,840 Speaker 1: a chance to go left or a chance to go right. 207 00:11:14,040 --> 00:11:16,720 Speaker 1: And the coin is very delicately balanced on its edge, 208 00:11:16,760 --> 00:11:19,560 Speaker 1: so that it's super sensitive to exactly how you flipped it, 209 00:11:19,760 --> 00:11:22,440 Speaker 1: and the wind conditions and if your partner is glaring 210 00:11:22,480 --> 00:11:25,440 Speaker 1: at you or whatever. All these tiny details which make 211 00:11:25,480 --> 00:11:29,640 Speaker 1: it effectively impossible to predict. Lets the coin and the 212 00:11:29,720 --> 00:11:33,280 Speaker 1: dice do its job, and we use chaos because we 213 00:11:33,360 --> 00:11:37,880 Speaker 1: don't have in our normal, everyday life access to true randomness, 214 00:11:38,120 --> 00:11:40,440 Speaker 1: by which I mean something which if you ran it 215 00:11:40,559 --> 00:11:43,880 Speaker 1: exactly the same way multiple times, would give you different 216 00:11:43,920 --> 00:11:48,280 Speaker 1: answers a spectrum of answers determined by some probability distribution. 217 00:11:48,760 --> 00:11:51,000 Speaker 2: But the good news is when I use the random 218 00:11:51,080 --> 00:11:54,360 Speaker 2: number generator on my computer, I do get random numbers, 219 00:11:54,400 --> 00:11:55,800 Speaker 2: and the statistician should. 220 00:11:55,640 --> 00:11:56,360 Speaker 3: Leave me alone. 221 00:11:57,240 --> 00:12:02,840 Speaker 1: This is rage base wrong, unfortunately, because how does your 222 00:12:02,840 --> 00:12:05,840 Speaker 1: computer work? Right? Your computer is not a quantum computer. 223 00:12:06,160 --> 00:12:09,600 Speaker 1: It's a classical computer. It's deterministic. That's the best thing 224 00:12:09,720 --> 00:12:12,440 Speaker 1: about the computer is that if you run the same 225 00:12:12,480 --> 00:12:15,160 Speaker 1: program twice you get the same answer. What else could 226 00:12:15,200 --> 00:12:18,600 Speaker 1: it do? Right? It's literally just following the rules of 227 00:12:18,679 --> 00:12:22,640 Speaker 1: digital logic, which are crisp and deterministic. And so you 228 00:12:22,760 --> 00:12:25,959 Speaker 1: run a random number generator on your computer, what is 229 00:12:26,000 --> 00:12:29,400 Speaker 1: it doing. It generates a string of digits and it 230 00:12:29,440 --> 00:12:32,320 Speaker 1: picks one for you. This is not a random string. 231 00:12:32,679 --> 00:12:34,520 Speaker 1: You set the seed to the same value, you get 232 00:12:34,559 --> 00:12:37,720 Speaker 1: the same series of digits. They are roughly distributed in 233 00:12:37,720 --> 00:12:40,640 Speaker 1: a uniform manner between two different numbers, and so in 234 00:12:40,679 --> 00:12:44,320 Speaker 1: that sense they're useful, but they're not actually random because again, 235 00:12:44,360 --> 00:12:47,840 Speaker 1: the same initial conditions lead to the same string of numbers. 236 00:12:48,200 --> 00:12:51,240 Speaker 2: So if you were to use a random process to 237 00:12:51,600 --> 00:12:56,360 Speaker 2: create ten numbers and a chaotic process to create ten numbers, like, 238 00:12:56,520 --> 00:13:01,280 Speaker 2: how meaningfully different would your result be? Are the statisticians 239 00:13:01,320 --> 00:13:01,920 Speaker 2: being silly? 240 00:13:03,320 --> 00:13:06,360 Speaker 1: Statisticians are very silly because they also have this concept 241 00:13:06,440 --> 00:13:09,960 Speaker 1: they call a random variable, which isn't random in the 242 00:13:10,000 --> 00:13:12,040 Speaker 1: sense that we're talking about from a physics point of view. 243 00:13:12,080 --> 00:13:15,400 Speaker 1: It's like a mapping between outcomes and numbers on the 244 00:13:15,440 --> 00:13:18,200 Speaker 1: number line, which really is not random at all, And 245 00:13:18,200 --> 00:13:21,760 Speaker 1: so it's like totally misnamed statisticians. Feel free to email 246 00:13:21,840 --> 00:13:24,240 Speaker 1: me hate messages about this, but I will stand by 247 00:13:24,280 --> 00:13:27,560 Speaker 1: this position. So your question is like does it matter? 248 00:13:28,120 --> 00:13:31,560 Speaker 1: And mostly it doesn't, which is why it takes really clever, 249 00:13:32,000 --> 00:13:36,400 Speaker 1: very subtle experiments to distinguish between a universe where things 250 00:13:36,480 --> 00:13:39,360 Speaker 1: really are random with the microscopic level, and things are 251 00:13:39,400 --> 00:13:42,720 Speaker 1: deterministic and chaotic. And we'll get into those experiments in 252 00:13:42,720 --> 00:13:46,640 Speaker 1: a minute. But philosophically it makes a big difference. Right. 253 00:13:47,040 --> 00:13:49,000 Speaker 1: It tells you that you live in a very different 254 00:13:49,120 --> 00:13:52,840 Speaker 1: universe if the laws are deterministic and if the laws 255 00:13:52,880 --> 00:13:56,920 Speaker 1: are probabilistic. Right, let's start with deterministic laws. If the 256 00:13:57,040 --> 00:14:00,320 Speaker 1: universe is fully deterministic, meaning that the currency set up 257 00:14:00,320 --> 00:14:03,600 Speaker 1: of the universe, every particle where it is its velocity 258 00:14:04,120 --> 00:14:08,240 Speaker 1: determines the future completely. That says something really powerful about 259 00:14:08,240 --> 00:14:11,400 Speaker 1: the universe. It says the future is determined right What's 260 00:14:11,440 --> 00:14:14,600 Speaker 1: going to happen tomorrow may be hard to calculate, may 261 00:14:14,720 --> 00:14:17,880 Speaker 1: require a supercomputer, and may depend on a butterfly's wings, 262 00:14:18,040 --> 00:14:22,040 Speaker 1: But in principle, there is only one possible future, and 263 00:14:22,080 --> 00:14:23,920 Speaker 1: we might not be able to extract it from our 264 00:14:23,960 --> 00:14:27,800 Speaker 1: limited knowledge of the current situation and our limited ability 265 00:14:27,800 --> 00:14:30,560 Speaker 1: to computationally apply the laws of physics. But in principle 266 00:14:30,600 --> 00:14:33,360 Speaker 1: it is determined by the current state of the universe. 267 00:14:33,800 --> 00:14:38,440 Speaker 1: So that deterministic universe, like a clockwork universe, is amazing 268 00:14:38,480 --> 00:14:41,200 Speaker 1: and fascinating, but also kind of scary because like, hmmm, 269 00:14:41,560 --> 00:14:43,600 Speaker 1: how do I fit into that? Am I just a 270 00:14:43,720 --> 00:14:46,520 Speaker 1: robot following the conditions of the universe? 271 00:14:46,760 --> 00:14:49,960 Speaker 2: Okay, So just to summarize real quick, if it's chaotic, 272 00:14:50,000 --> 00:14:52,680 Speaker 2: then if you rewind a situation and play it forward again, 273 00:14:52,720 --> 00:14:55,680 Speaker 2: you'll get the exact same results. And if it's random, 274 00:14:55,920 --> 00:14:59,280 Speaker 2: then you'll rewind the situation and even if everything about 275 00:14:59,280 --> 00:15:01,440 Speaker 2: the situation say the same, you're going to get a 276 00:15:01,480 --> 00:15:02,880 Speaker 2: different result exactly. 277 00:15:03,360 --> 00:15:05,960 Speaker 1: And there's something really subtle there, which I think is 278 00:15:06,000 --> 00:15:09,520 Speaker 1: often overlooked about what it means to be random, because 279 00:15:09,560 --> 00:15:13,440 Speaker 1: random is not arbitrary. Right, We're not saying, look, whatever 280 00:15:13,480 --> 00:15:17,080 Speaker 1: happens just happens. By happ the universe is lawless. Right, 281 00:15:17,120 --> 00:15:22,040 Speaker 1: we still have laws of physics. Quantum mechanics is actually deterministic, 282 00:15:22,120 --> 00:15:24,560 Speaker 1: and that's a very confusing thing to say, but hold 283 00:15:24,560 --> 00:15:27,160 Speaker 1: on for a moment. Is deterministic in a different way 284 00:15:27,360 --> 00:15:31,360 Speaker 1: than classical physics. Classical physics says you hit the cue 285 00:15:31,400 --> 00:15:33,000 Speaker 1: ball the same way, you're always going to get the 286 00:15:33,000 --> 00:15:35,080 Speaker 1: same outcome. You flip the coin the same way, you're 287 00:15:35,120 --> 00:15:38,080 Speaker 1: always going to get the same outcome. Quantum mechanics says 288 00:15:38,480 --> 00:15:40,440 Speaker 1: you run the same experiment twice, you don't get the 289 00:15:40,440 --> 00:15:44,320 Speaker 1: same outcome, but you get exactly the same probability of outcomes. 290 00:15:44,680 --> 00:15:47,800 Speaker 1: So physics doesn't give up, It just retreats one step. 291 00:15:47,880 --> 00:15:50,480 Speaker 1: It says, I can't tell you exactly what's going to 292 00:15:50,520 --> 00:15:55,200 Speaker 1: happen for any individual experiment, but I do absolutely determine 293 00:15:55,200 --> 00:15:59,160 Speaker 1: the probabilities of various things happening. So some thing's impossible 294 00:15:59,200 --> 00:16:02,280 Speaker 1: to happen, zero probability, they will never happen. Other things 295 00:16:02,400 --> 00:16:05,840 Speaker 1: very likely. Some thing's very improbable. So for example, when 296 00:16:05,880 --> 00:16:08,760 Speaker 1: we smash particles together at the large Hadron collider, we 297 00:16:08,800 --> 00:16:10,800 Speaker 1: don't know and we can't know what's going to happen 298 00:16:10,840 --> 00:16:14,200 Speaker 1: for any individual collision, but we can and we do 299 00:16:14,440 --> 00:16:17,880 Speaker 1: calculate the probabilities of X happening or why happening or 300 00:16:17,960 --> 00:16:20,560 Speaker 1: Z happening, and then we go off and we measure 301 00:16:20,560 --> 00:16:22,480 Speaker 1: the rates of which those things happen. We compare them 302 00:16:22,480 --> 00:16:25,960 Speaker 1: to our calculations, and they agree. So quantum mechanics is 303 00:16:26,000 --> 00:16:29,160 Speaker 1: not arbitrary. It's just deterministic in a different way. It's 304 00:16:29,200 --> 00:16:33,840 Speaker 1: like generalizing determinism, not at the individual experiment level, but 305 00:16:33,880 --> 00:16:36,000 Speaker 1: at the possibilities of the outcomes. 306 00:16:36,200 --> 00:16:39,360 Speaker 2: Okay, all right, I totally followed that. And so if 307 00:16:39,360 --> 00:16:44,280 Speaker 2: you want to get true random numbers, do you have 308 00:16:44,480 --> 00:16:47,000 Speaker 2: to be doing quantum mechanics or are there other ways 309 00:16:47,000 --> 00:16:48,400 Speaker 2: to get random numbers? 310 00:16:48,600 --> 00:16:51,080 Speaker 1: Quantum mechanics is, as far as I know, the only 311 00:16:51,200 --> 00:16:55,920 Speaker 1: source of true randomness in the universe. All classical physics 312 00:16:56,440 --> 00:17:00,400 Speaker 1: is deterministic, right, Every classical theory depends on the initial conditions, 313 00:17:00,400 --> 00:17:04,040 Speaker 1: and the outcomes are totally determined by those initial conditions. 314 00:17:04,480 --> 00:17:07,840 Speaker 1: And so classical physics, yeah, totally deterministic and philosophically, this 315 00:17:08,040 --> 00:17:11,159 Speaker 1: was like mind blowing for people once they understood it 316 00:17:11,200 --> 00:17:13,879 Speaker 1: before we had quantum mechanics, they were like, oh my gosh, wow, 317 00:17:14,119 --> 00:17:17,200 Speaker 1: seems like the universe is deterministic. We are all effectively 318 00:17:17,200 --> 00:17:22,680 Speaker 1: philosophical clocks, right, we're robots determined by the early universe. 319 00:17:22,760 --> 00:17:25,639 Speaker 1: And you know, us being on this podcast was set 320 00:17:25,680 --> 00:17:28,520 Speaker 1: in stone once we had the universe at a certain 321 00:17:28,520 --> 00:17:33,840 Speaker 1: stage billions of years ago, and then quantum mechanics says, actually, no, 322 00:17:34,000 --> 00:17:37,680 Speaker 1: there's an important layer at which the universe is not deterministic. 323 00:17:37,680 --> 00:17:40,960 Speaker 1: There's a probabilistic nature there. There's some randomness there. 324 00:17:41,040 --> 00:17:43,280 Speaker 2: So the world is lucky that we ended up doing 325 00:17:43,280 --> 00:17:44,040 Speaker 2: this podcast. 326 00:17:45,680 --> 00:17:48,520 Speaker 1: Well, it opened up a whole rabbits hole of philosophical 327 00:17:48,600 --> 00:17:51,800 Speaker 1: questions like does that actually allow for free will? And 328 00:17:51,880 --> 00:17:53,840 Speaker 1: you know my answer is, I'm not sure it does, 329 00:17:53,960 --> 00:17:56,960 Speaker 1: because the universe is not arbitrary. It doesn't open the 330 00:17:57,000 --> 00:18:00,240 Speaker 1: door for like mind body duality, where you can have 331 00:18:00,359 --> 00:18:04,040 Speaker 1: like some non physical mind now affecting the physical universe. 332 00:18:04,400 --> 00:18:06,960 Speaker 1: It just says that there's some randomness, right, and free 333 00:18:06,960 --> 00:18:09,840 Speaker 1: will is not randomness. Right. When you go to choose 334 00:18:09,840 --> 00:18:12,080 Speaker 1: ice cream at the store, you're making a choice for 335 00:18:12,200 --> 00:18:16,439 Speaker 1: chunky monkey. Right, it's not randomly decided. And so anyway, 336 00:18:16,440 --> 00:18:18,560 Speaker 1: that's a whole philosolphal rabbit hole. We're not going to 337 00:18:18,640 --> 00:18:20,560 Speaker 1: go down to this hole. 338 00:18:22,760 --> 00:18:24,439 Speaker 2: It's an important it's. 339 00:18:24,320 --> 00:18:27,960 Speaker 1: A pretty chunky rabbit hole, yes, for sure. But let's 340 00:18:27,960 --> 00:18:31,000 Speaker 1: take one more step towards entanglement. So so far we've 341 00:18:31,000 --> 00:18:34,679 Speaker 1: talked about randomness and what that means. And so let's imagine, 342 00:18:34,720 --> 00:18:38,600 Speaker 1: for example, a classical coin. Right, you flip it, it's 343 00:18:38,680 --> 00:18:42,320 Speaker 1: hard to predict, but it is determined. Imagine now you 344 00:18:42,400 --> 00:18:46,040 Speaker 1: had some quantum version, a coin which you could flip 345 00:18:46,080 --> 00:18:48,719 Speaker 1: and was really random, right, It was not determined by 346 00:18:48,760 --> 00:18:52,080 Speaker 1: the initial conditions. The other amazing thing about this quantum 347 00:18:52,080 --> 00:18:56,600 Speaker 1: coin is that it preserves both possibilities until you look. 348 00:18:57,280 --> 00:18:59,720 Speaker 1: So the classical coin, you flip it, it lands in 349 00:18:59,720 --> 00:19:02,160 Speaker 1: your hand and you cover it up. But under your 350 00:19:02,160 --> 00:19:04,719 Speaker 1: hand it is heads or it is tails, right, you 351 00:19:04,800 --> 00:19:07,639 Speaker 1: just don't know it yet. The quantum coin you flip 352 00:19:07,640 --> 00:19:10,640 Speaker 1: it is under your hand until you look, it has 353 00:19:10,640 --> 00:19:13,880 Speaker 1: the superposition of all the possibilities. Maybe it's heads, maybe 354 00:19:13,960 --> 00:19:17,880 Speaker 1: it's tails. Right, So, not only is quantum mechanics random, 355 00:19:17,920 --> 00:19:21,359 Speaker 1: but it's also undetermined until it's measured, which is going 356 00:19:21,400 --> 00:19:24,439 Speaker 1: to be an important factor in our later conversations. So 357 00:19:24,480 --> 00:19:28,199 Speaker 1: that quantum coin is undetermined, and that's weird, and you 358 00:19:28,200 --> 00:19:30,480 Speaker 1: can ask the same question you asked a minute ago, like, well, 359 00:19:30,680 --> 00:19:33,320 Speaker 1: how different is it because you look, it's got an answer. 360 00:19:33,400 --> 00:19:36,080 Speaker 1: How do you really know it's undetermined? How do you 361 00:19:36,119 --> 00:19:37,720 Speaker 1: really know it's random? And how do you really know 362 00:19:37,760 --> 00:19:39,600 Speaker 1: that it's undetermined until you look? 363 00:19:39,880 --> 00:19:40,120 Speaker 7: Yeah? 364 00:19:40,200 --> 00:19:41,960 Speaker 2: Right? And this is where I help the whole field 365 00:19:42,000 --> 00:19:44,480 Speaker 2: of physics by letting you all know you've just got 366 00:19:44,520 --> 00:19:48,359 Speaker 2: to be wrong about that. That doesn't feel like it 367 00:19:48,400 --> 00:19:50,760 Speaker 2: makes any sense to me, and so go back to 368 00:19:50,800 --> 00:19:56,240 Speaker 2: the drawing table and try again. Guys and gals. All right, 369 00:19:56,280 --> 00:19:59,320 Speaker 2: So we are about five percent of the way through 370 00:19:59,320 --> 00:20:02,200 Speaker 2: our outline and about a third of the way through 371 00:20:02,240 --> 00:20:05,720 Speaker 2: our episode. I got really excited about randomness and chaos. 372 00:20:06,040 --> 00:20:09,120 Speaker 2: Let's take a break, get ourselves back on track, and 373 00:20:09,160 --> 00:20:12,000 Speaker 2: when we come back, Daniel will convince me that I'm 374 00:20:12,040 --> 00:20:13,240 Speaker 2: wrong about all the physics. 375 00:20:17,119 --> 00:20:20,200 Speaker 1: Wait, so your homework is check Daniel CV. My homework 376 00:20:20,280 --> 00:20:23,359 Speaker 1: is convinced Kelly that all the physics is correct. Wow, 377 00:20:23,440 --> 00:20:26,000 Speaker 1: this doesn't feel like an equitable distribution of tasks. 378 00:20:26,119 --> 00:20:27,840 Speaker 2: Well, you know, if physics got things right in the 379 00:20:27,840 --> 00:20:31,480 Speaker 2: first place, you wouldn't have to worry about this. This 380 00:20:31,520 --> 00:20:33,199 Speaker 2: is why you gotta be in biology. You know, we 381 00:20:33,200 --> 00:20:35,160 Speaker 2: got it all figured out. It depends. 382 00:20:36,640 --> 00:20:38,040 Speaker 1: Nothing's right or wrong anyway. 383 00:20:38,119 --> 00:20:40,360 Speaker 4: So yeah, there you go, there you go. All right, 384 00:20:40,440 --> 00:20:56,200 Speaker 4: let's take that break. 385 00:21:01,160 --> 00:21:04,119 Speaker 2: Okay, So at the end of our last session, I 386 00:21:04,200 --> 00:21:07,960 Speaker 2: dropped the bombshell that all of physics is wrong, and 387 00:21:08,160 --> 00:21:11,760 Speaker 2: Daniel is going to let me know why he thinks 388 00:21:11,800 --> 00:21:15,360 Speaker 2: I'm wrong. So, all right, Daniel, quantum entanglement. How can 389 00:21:15,400 --> 00:21:17,680 Speaker 2: that coin that you flipped and it's in your hand 390 00:21:17,720 --> 00:21:20,240 Speaker 2: but you've covered it. How can it be both heads 391 00:21:20,240 --> 00:21:23,960 Speaker 2: and tails superimposed at the same time but doesn't actually 392 00:21:24,080 --> 00:21:26,360 Speaker 2: end up as one until you move your hand away. 393 00:21:26,640 --> 00:21:29,480 Speaker 1: Yeah, it's bizarre. And to really probe this, we're gonna 394 00:21:29,520 --> 00:21:32,760 Speaker 1: have to make this setup one step more complicated and 395 00:21:32,880 --> 00:21:36,200 Speaker 1: even more counterintuitive. And so to explain this, we're gonna 396 00:21:36,200 --> 00:21:38,720 Speaker 1: have to make this setup a little bit more complicated. 397 00:21:38,760 --> 00:21:41,360 Speaker 1: We're gonna need two objects, and we're gonna need them 398 00:21:41,640 --> 00:21:43,800 Speaker 1: to be connected in an important way. We go need 399 00:21:43,840 --> 00:21:46,840 Speaker 1: their fates to be connected. And so instead of having 400 00:21:46,840 --> 00:21:48,920 Speaker 1: a coin, let's imagine that we have two bags. One 401 00:21:48,960 --> 00:21:50,480 Speaker 1: has a red ball in it and one has a 402 00:21:50,480 --> 00:21:52,879 Speaker 1: blue ball in it. Okay, and these are just classical, 403 00:21:52,920 --> 00:21:55,320 Speaker 1: normal balls, it's no big deal. And I have one 404 00:21:55,359 --> 00:21:57,919 Speaker 1: and Kelly has the other, and we pick bags and 405 00:21:57,960 --> 00:22:00,960 Speaker 1: we go back to our homes. I'm in California, you're Virginia. 406 00:22:01,000 --> 00:22:02,760 Speaker 1: And I look in my bag and I see that 407 00:22:02,840 --> 00:22:05,080 Speaker 1: I have the blue ball in my bag. Now, I 408 00:22:05,160 --> 00:22:08,040 Speaker 1: instantly know that you have the red ball, right, because 409 00:22:08,080 --> 00:22:10,479 Speaker 1: we knew there was one blue and one red. And 410 00:22:10,520 --> 00:22:12,240 Speaker 1: I know you have the red ball because I'm applying 411 00:22:12,240 --> 00:22:15,440 Speaker 1: this constraint, this condition, this requirement that there was only 412 00:22:15,480 --> 00:22:17,800 Speaker 1: one blue and one red, and therefore, if I had 413 00:22:17,800 --> 00:22:20,199 Speaker 1: the blue, you have to have the red. No magic 414 00:22:20,240 --> 00:22:25,080 Speaker 1: at all, right, And also no instantaneous communication of information, right, 415 00:22:25,119 --> 00:22:28,000 Speaker 1: Like I know instantly that you have the red ball. 416 00:22:28,240 --> 00:22:31,159 Speaker 1: You don't know that, right. I know that I know 417 00:22:31,200 --> 00:22:33,560 Speaker 1: something about a ball that's really far away, and I 418 00:22:33,640 --> 00:22:37,440 Speaker 1: know that instantly. But again, there's been no instantaneous communication 419 00:22:37,640 --> 00:22:39,320 Speaker 1: of information, right. 420 00:22:39,800 --> 00:22:42,080 Speaker 2: I Mean, I'll be honest, Daniel, I probably peaked. 421 00:22:42,840 --> 00:22:45,120 Speaker 1: You are a cheater, aren't you. I knew that about you. 422 00:22:47,520 --> 00:22:50,960 Speaker 2: Okay, But I totally understand the scenario you've laid out. 423 00:22:50,800 --> 00:22:53,399 Speaker 1: All right, Now, let's imagine the quantum version and the 424 00:22:53,520 --> 00:22:57,480 Speaker 1: quantum version things are different. Okay, So number one, it's 425 00:22:57,560 --> 00:23:00,199 Speaker 1: not determined who has the blue and the red. Like 426 00:23:00,240 --> 00:23:02,159 Speaker 1: in the classical version, I had the blue one the 427 00:23:02,160 --> 00:23:05,200 Speaker 1: whole time, I just didn't know it, right. In the 428 00:23:05,280 --> 00:23:08,320 Speaker 1: quantum version, it's not determined I could have the blue 429 00:23:08,480 --> 00:23:10,520 Speaker 1: or the red. And so the ball is in this 430 00:23:10,720 --> 00:23:13,919 Speaker 1: undetermined state. It has a probability of being red and 431 00:23:13,960 --> 00:23:17,240 Speaker 1: a probability of being blue, and your ball is also 432 00:23:17,680 --> 00:23:19,679 Speaker 1: has a probability of being red and a probability of 433 00:23:19,680 --> 00:23:23,199 Speaker 1: being blue. But because we know there's only one blue ball, 434 00:23:23,640 --> 00:23:26,240 Speaker 1: if I look inside my bag and I see the 435 00:23:26,240 --> 00:23:29,200 Speaker 1: blue ball, now I know you have a red ball, right, 436 00:23:29,840 --> 00:23:33,040 Speaker 1: And so then something amazing happens. My ball goes from 437 00:23:33,240 --> 00:23:35,600 Speaker 1: both possibilities to being blue, and at the same time, 438 00:23:35,720 --> 00:23:39,240 Speaker 1: your ball goes from both possibilities to only one possibility 439 00:23:39,280 --> 00:23:40,200 Speaker 1: of being red. 440 00:23:40,400 --> 00:23:46,119 Speaker 2: Okay, So is the ball both blue and red or 441 00:23:46,200 --> 00:23:49,800 Speaker 2: it's just neither? Until you look, what is the right 442 00:23:49,840 --> 00:23:50,920 Speaker 2: way to be thinking about this? 443 00:23:51,240 --> 00:23:54,159 Speaker 1: Yeah, so people like to say that it's both things 444 00:23:54,160 --> 00:23:56,240 Speaker 1: at the same time. Electrons going to be in multiple 445 00:23:56,240 --> 00:23:58,840 Speaker 1: places at the same time. I think that's confusing in 446 00:23:58,840 --> 00:24:01,960 Speaker 1: a way that doesn't educate and isn't accurate, because it's 447 00:24:02,000 --> 00:24:04,840 Speaker 1: not true that it's in both locations at the same time, 448 00:24:04,960 --> 00:24:07,560 Speaker 1: or that it has both colors. It just has the 449 00:24:07,600 --> 00:24:11,160 Speaker 1: probability to have both colors, and it's not yet determined, right, 450 00:24:11,240 --> 00:24:13,040 Speaker 1: So it doesn't make any sense to say the ball 451 00:24:13,119 --> 00:24:15,280 Speaker 1: is blue and it's red, or it has both colors. 452 00:24:15,600 --> 00:24:17,920 Speaker 1: It's just that it has both possibilities and we don't 453 00:24:17,920 --> 00:24:21,480 Speaker 1: know yet, and the universe has not yet decided, right. 454 00:24:22,000 --> 00:24:23,640 Speaker 1: And the weird thing about this is like, how can 455 00:24:23,680 --> 00:24:26,200 Speaker 1: you tell? Right, all I'm doing is I'm picking a bag, 456 00:24:26,240 --> 00:24:28,399 Speaker 1: I'm going to California and opening up, I'm seeing it's blue. 457 00:24:28,640 --> 00:24:31,359 Speaker 1: How do I know that the universe didn't actually just 458 00:24:31,440 --> 00:24:34,280 Speaker 1: decide when I picked the ball which one I had 459 00:24:34,280 --> 00:24:36,520 Speaker 1: in which one you had? How can I tell that 460 00:24:36,640 --> 00:24:40,760 Speaker 1: it was really uncertain and that it really is random? 461 00:24:41,320 --> 00:24:43,040 Speaker 1: And that's the crux of the question. That's what we 462 00:24:43,080 --> 00:24:47,240 Speaker 1: want to know, like what's really going on inside these bags? 463 00:24:47,640 --> 00:24:49,720 Speaker 1: And of course when we do these experiments, there are 464 00:24:49,760 --> 00:24:52,439 Speaker 1: no quantum versions of balls and bags, and so we 465 00:24:52,480 --> 00:24:55,280 Speaker 1: do it with particles, and we do with particles that 466 00:24:55,320 --> 00:24:59,280 Speaker 1: are constrained by laws of physics to have some opposite characteristic. So, 467 00:24:59,320 --> 00:25:02,680 Speaker 1: for example, you create two electrons in such a way 468 00:25:02,800 --> 00:25:04,360 Speaker 1: that one has to be spin up and the other 469 00:25:04,359 --> 00:25:07,000 Speaker 1: one has to be spinned down to conserve angular momentum. 470 00:25:07,400 --> 00:25:09,480 Speaker 1: And so when you measure one, you learn that it's 471 00:25:09,480 --> 00:25:11,399 Speaker 1: spin up. You know, the other one has to be 472 00:25:11,440 --> 00:25:14,840 Speaker 1: spinned down. And that's just because we need a quantum property. 473 00:25:14,840 --> 00:25:17,240 Speaker 1: You have a quantum object. And we've been talking about 474 00:25:17,280 --> 00:25:20,159 Speaker 1: bags and balls, but there aren't actually quantum bags and balls, 475 00:25:20,160 --> 00:25:22,399 Speaker 1: and so in the real world we do this with 476 00:25:22,520 --> 00:25:23,840 Speaker 1: spin and with particles. 477 00:25:24,320 --> 00:25:27,360 Speaker 2: So I think when we were talking about quantum internet, 478 00:25:28,560 --> 00:25:33,040 Speaker 2: you explain some of this there. And I asked how 479 00:25:33,080 --> 00:25:37,199 Speaker 2: this differs than the Schrodinger's cat example, is like, is 480 00:25:37,200 --> 00:25:40,080 Speaker 2: the cat both alive and dead? And I think you 481 00:25:40,240 --> 00:25:43,520 Speaker 2: told me that that's not even almost about what we're 482 00:25:43,560 --> 00:25:48,200 Speaker 2: talking about, but I've forgotten because my memory is great. 483 00:25:48,280 --> 00:25:50,160 Speaker 2: So how does this is this the same thing? 484 00:25:50,560 --> 00:25:53,480 Speaker 1: This is the same concept? Yes, okay, The schirtingers Koint 485 00:25:53,520 --> 00:25:56,000 Speaker 1: experiment says you have a cat in a box and 486 00:25:56,359 --> 00:25:59,320 Speaker 1: it's going to be killed based on some quantum process 487 00:25:59,359 --> 00:26:03,080 Speaker 1: which is un predictable, right, It's truly random, and it 488 00:26:03,119 --> 00:26:05,480 Speaker 1: does this thing. We're trying to connect that quantum process 489 00:26:05,520 --> 00:26:08,960 Speaker 1: to something classical and intuitive, which is a cat. And 490 00:26:09,080 --> 00:26:11,800 Speaker 1: so you know, before you open the box, the cat 491 00:26:11,880 --> 00:26:14,760 Speaker 1: has a probability being alive and a probability of being dead. 492 00:26:14,760 --> 00:26:16,959 Speaker 1: And people like to say it's both dead and alive, 493 00:26:17,000 --> 00:26:18,960 Speaker 1: which I don't think makes any sense. I think it 494 00:26:18,960 --> 00:26:21,439 Speaker 1: has a probability of being dead and a probability of 495 00:26:21,480 --> 00:26:24,400 Speaker 1: being alive. And the quantum version of the story is 496 00:26:24,440 --> 00:26:27,320 Speaker 1: that before you open the box, it has both probabilities 497 00:26:27,320 --> 00:26:30,760 Speaker 1: and the universe has not yet decided. And the classical 498 00:26:30,880 --> 00:26:33,280 Speaker 1: view of that it says, no, no, no, it's determined. 499 00:26:33,840 --> 00:26:36,760 Speaker 1: You just don't know until you open the box. And 500 00:26:36,800 --> 00:26:40,360 Speaker 1: the question, the deep question, is can we tell the difference? 501 00:26:40,720 --> 00:26:43,520 Speaker 1: Can we really know if the universe is playing this 502 00:26:43,720 --> 00:26:48,040 Speaker 1: undetermined random game, which would be really really strange, or 503 00:26:48,119 --> 00:26:50,399 Speaker 1: is there some way in which the universe decides all 504 00:26:50,440 --> 00:26:52,960 Speaker 1: this stuff in advance and it's all predetermined. We just 505 00:26:53,160 --> 00:26:56,240 Speaker 1: don't know how it does it. It's just some hidden 506 00:26:56,320 --> 00:26:59,480 Speaker 1: detail that we're missing that tells one particle to go 507 00:26:59,560 --> 00:27:01,920 Speaker 1: up and particles go down. And so those are the 508 00:27:01,920 --> 00:27:05,080 Speaker 1: two questions. Is it actually random and quantum mechanical and 509 00:27:05,200 --> 00:27:10,120 Speaker 1: undetermined or is there some hidden variable, some detail which 510 00:27:10,200 --> 00:27:13,680 Speaker 1: is controlling this that we just are missing or not understanding. 511 00:27:13,840 --> 00:27:16,520 Speaker 2: All right, so how could you possibly tell the difference? 512 00:27:16,560 --> 00:27:17,800 Speaker 2: What experiments do we need to do? 513 00:27:18,080 --> 00:27:20,879 Speaker 1: Well, the best thing to do is the most obvious. 514 00:27:20,920 --> 00:27:23,520 Speaker 1: It's like, well, just repeat the experiment multiple times, start 515 00:27:23,520 --> 00:27:26,199 Speaker 1: it exactly the same way, set it up exactly the 516 00:27:26,240 --> 00:27:28,680 Speaker 1: same way, or the balls or the electrons or whatever, 517 00:27:28,920 --> 00:27:31,760 Speaker 1: and see do you get different outcomes? Because if you 518 00:27:31,880 --> 00:27:34,200 Speaker 1: do it the same way, starting with exactly the same 519 00:27:34,240 --> 00:27:38,080 Speaker 1: initial conditions multiple times, and you always get the same outcome, 520 00:27:38,480 --> 00:27:40,560 Speaker 1: then you know it's determined. And if you use these 521 00:27:40,640 --> 00:27:43,159 Speaker 1: same initial conditions and you get different outcomes, then you 522 00:27:43,240 --> 00:27:45,800 Speaker 1: know that it's not. That sounds great, right, what a 523 00:27:45,840 --> 00:27:49,520 Speaker 1: clean experiment, Just test it. The problem is how do 524 00:27:49,600 --> 00:27:53,320 Speaker 1: you do the same experiment exactly the same way twice? Right? 525 00:27:53,440 --> 00:27:55,560 Speaker 1: Like you know you can never step in the same 526 00:27:55,680 --> 00:27:58,800 Speaker 1: river twice. If you repeat an experiment the next day, 527 00:27:58,880 --> 00:28:00,920 Speaker 1: the Earth is in a different place around the sun 528 00:28:01,000 --> 00:28:02,879 Speaker 1: and the temperature are slightly different, and you had a 529 00:28:02,880 --> 00:28:05,680 Speaker 1: different breakfast, and there's like a zillion things that you 530 00:28:05,720 --> 00:28:09,720 Speaker 1: could never control for, and the quantum philosophy nerds are 531 00:28:09,760 --> 00:28:13,680 Speaker 1: like really nerdy about all these loopholes, and so that's 532 00:28:13,720 --> 00:28:16,639 Speaker 1: just impossible. Even at the particle accelerator, Like we smashed 533 00:28:16,640 --> 00:28:19,480 Speaker 1: protons together millions of times a second, but it's never 534 00:28:19,600 --> 00:28:22,399 Speaker 1: exactly the same collision. The angles are slightly different, the 535 00:28:22,480 --> 00:28:26,199 Speaker 1: energies are slightly different, and so that's essentially impossible. So 536 00:28:26,240 --> 00:28:28,840 Speaker 1: we need something more clever. You can't just run the 537 00:28:28,840 --> 00:28:31,439 Speaker 1: same experiment twice, which is a bummer, because man, that 538 00:28:31,440 --> 00:28:32,200 Speaker 1: would be awesome. 539 00:28:32,400 --> 00:28:35,000 Speaker 2: That would be awesome. Okay, but I'm hoping physicists haven't 540 00:28:35,040 --> 00:28:37,920 Speaker 2: just thrown in the towel. But maybe all did because 541 00:28:37,920 --> 00:28:39,720 Speaker 2: you were like, oh, shoot, we're probably wrong. 542 00:28:40,400 --> 00:28:42,880 Speaker 1: No, okay, no, we did not throw in the towel. 543 00:28:42,960 --> 00:28:45,160 Speaker 1: There was a very clever guy named John Bell who 544 00:28:45,240 --> 00:28:47,720 Speaker 1: came up with an experiment that could tell us the 545 00:28:47,760 --> 00:28:51,280 Speaker 1: difference between these two hypotheses. One that the universe has 546 00:28:51,400 --> 00:28:54,840 Speaker 1: somehow figured this out in advance and we just are 547 00:28:54,880 --> 00:28:59,040 Speaker 1: missing the information, and two that know it's actually random 548 00:28:59,120 --> 00:29:02,880 Speaker 1: and undetermined until you look that these particles, even when 549 00:29:02,880 --> 00:29:06,960 Speaker 1: they're separated by great distance, somehow decide together at the 550 00:29:07,000 --> 00:29:09,480 Speaker 1: same moment which one is up and which one is down. 551 00:29:10,040 --> 00:29:12,120 Speaker 1: And it sounds like impossible to tell the difference, but 552 00:29:12,120 --> 00:29:14,920 Speaker 1: he came up with this really clever way. And unfortunately 553 00:29:14,960 --> 00:29:18,680 Speaker 1: there's no like smoking gun individual experiment where you can 554 00:29:18,720 --> 00:29:21,600 Speaker 1: say I'm looking at the outcome and it proves a 555 00:29:21,800 --> 00:29:25,320 Speaker 1: versus b right. This is not like do unicorns exist 556 00:29:25,440 --> 00:29:28,280 Speaker 1: or I found one, therefore we know there are unicorns. 557 00:29:28,800 --> 00:29:34,560 Speaker 1: The results are a subtle statistical correlation across many experiments. 558 00:29:34,800 --> 00:29:38,640 Speaker 2: So is it a quantum result. There's a constant probability 559 00:29:38,640 --> 00:29:39,320 Speaker 2: that you're wrong. 560 00:29:40,120 --> 00:29:46,000 Speaker 1: And briefly, you take measurements of these two distant, entangled 561 00:29:46,000 --> 00:29:48,400 Speaker 1: particles and you look at how often you get the 562 00:29:48,400 --> 00:29:51,800 Speaker 1: same result, and if they are hidden variables, you can't 563 00:29:51,840 --> 00:29:54,080 Speaker 1: get the same result more than two thirds of the time. 564 00:29:54,360 --> 00:29:57,200 Speaker 1: But quantum mechanics allows you to get the same result 565 00:29:57,280 --> 00:29:59,480 Speaker 1: on these two particles more than two thirds of the time. 566 00:29:59,520 --> 00:30:03,080 Speaker 1: It breaks that restriction by not determining the result in advance. 567 00:30:03,520 --> 00:30:06,400 Speaker 1: But it's a correlation, right, It's not like any individual 568 00:30:06,440 --> 00:30:10,160 Speaker 1: experiment proves it. It's like a pattern among many, many, 569 00:30:10,200 --> 00:30:14,640 Speaker 1: many runs of the experiment. So it's a little frustratingly indirect, 570 00:30:14,840 --> 00:30:17,240 Speaker 1: but it's also mathematically very crisp, and I want to 571 00:30:17,240 --> 00:30:18,400 Speaker 1: try to walk you through as you can get an 572 00:30:18,400 --> 00:30:21,280 Speaker 1: intuition for what's going on here. Okay, So how does 573 00:30:21,280 --> 00:30:23,680 Speaker 1: this Bell's experiment work? And why is two thirds an 574 00:30:23,680 --> 00:30:26,280 Speaker 1: important threshold? So imagine I have an electron here in 575 00:30:26,280 --> 00:30:29,360 Speaker 1: California and there's an electron in Virginia, and we've entangled them, 576 00:30:29,440 --> 00:30:30,880 Speaker 1: so we know if one is up, the other one 577 00:30:30,960 --> 00:30:33,840 Speaker 1: is down. So what are the possibilities If I measure up, 578 00:30:34,000 --> 00:30:37,920 Speaker 1: then Virginia is down. If California measures down, Virginia is up. Okay, 579 00:30:38,160 --> 00:30:40,560 Speaker 1: So we get opposite spins one hundred percent of the time. 580 00:30:40,840 --> 00:30:43,040 Speaker 1: So far. This is not evidence of anything. This just 581 00:30:43,080 --> 00:30:47,480 Speaker 1: says our particles are constrained. They're entangled, right, And it's 582 00:30:47,480 --> 00:30:49,920 Speaker 1: important for people to understand really what this means, because 583 00:30:49,920 --> 00:30:52,560 Speaker 1: a lot of people don't get the simplicity of what 584 00:30:52,720 --> 00:30:57,600 Speaker 1: entanglement means. The entanglement just removes some possible outcomes, like 585 00:30:57,640 --> 00:31:00,000 Speaker 1: without entanglement, I could get up and you could get 586 00:31:00,080 --> 00:31:02,080 Speaker 1: it up. I could get down and you could get down. 587 00:31:02,280 --> 00:31:05,920 Speaker 1: Entanglement just says no, those possibilities are zero. So entanglement 588 00:31:06,040 --> 00:31:09,440 Speaker 1: just removes possibilities and only leaves the ones that satisfy 589 00:31:09,840 --> 00:31:12,640 Speaker 1: in this case, like angler momentum. All right, so we 590 00:31:12,760 --> 00:31:14,640 Speaker 1: know that they have to be opposite. So far we 591 00:31:14,680 --> 00:31:18,360 Speaker 1: haven't learned anything. But remember that also I don't have 592 00:31:18,440 --> 00:31:21,520 Speaker 1: to measure spin in the same direction as you do. 593 00:31:21,960 --> 00:31:24,920 Speaker 1: We have three dimensions of space X, y, and Z right, 594 00:31:24,960 --> 00:31:27,480 Speaker 1: and I could measure spin along like a Z axis, 595 00:31:27,480 --> 00:31:30,240 Speaker 1: and you can measure it along a Y axis that's perpendicular. 596 00:31:30,960 --> 00:31:32,880 Speaker 1: Or for example, I can measure it in one direction 597 00:31:32,920 --> 00:31:35,680 Speaker 1: and you could flip your machine upside down. What happens 598 00:31:35,720 --> 00:31:38,120 Speaker 1: if you flip your machine upside down? Then we expect 599 00:31:38,120 --> 00:31:40,920 Speaker 1: that we always get the same answer. If I read up, 600 00:31:41,160 --> 00:31:43,400 Speaker 1: then you're also going to read up. I would have 601 00:31:43,440 --> 00:31:46,160 Speaker 1: read down on your particle, but your machine is upside down. 602 00:31:46,200 --> 00:31:48,320 Speaker 1: So I get up, you get up. If I get down, 603 00:31:48,520 --> 00:31:51,200 Speaker 1: you get down. So in that scenario we get the 604 00:31:51,200 --> 00:31:53,840 Speaker 1: same results one hundred percent of the time. Right where 605 00:31:53,840 --> 00:31:57,720 Speaker 1: our machines are flipped, but also the particles are entangled, 606 00:31:57,720 --> 00:32:00,480 Speaker 1: so they have opposite spins yep R with me still 607 00:32:00,680 --> 00:32:05,280 Speaker 1: uh huh okay. Bell's experiment says, let's get even weirder folks, 608 00:32:05,840 --> 00:32:09,200 Speaker 1: Let's pick three axes in advance. So like, I'm gonna 609 00:32:09,200 --> 00:32:13,400 Speaker 1: pick three directions in space, maybe up and then left 610 00:32:13,440 --> 00:32:16,600 Speaker 1: and then also some weird angle in between. Okay, so 611 00:32:16,640 --> 00:32:19,840 Speaker 1: we pick that in advance. We have our electrons, one 612 00:32:19,880 --> 00:32:24,360 Speaker 1: in California and one in Virginia. Now I randomly choose 613 00:32:24,960 --> 00:32:28,440 Speaker 1: which of those three axes I'm gonna measure my electron on? 614 00:32:28,920 --> 00:32:30,560 Speaker 1: Is it the Z? Is it? The Y? Is it 615 00:32:30,600 --> 00:32:33,800 Speaker 1: the in between? You're also gonna do that. You're gonna 616 00:32:33,880 --> 00:32:35,280 Speaker 1: randomly choose an axis? 617 00:32:35,560 --> 00:32:37,960 Speaker 2: Okay, how do I randomly choose an axis? 618 00:32:37,960 --> 00:32:38,080 Speaker 7: If? 619 00:32:38,120 --> 00:32:41,680 Speaker 2: I if randomness is so hard to uh, I can't 620 00:32:41,760 --> 00:32:45,440 Speaker 2: use the random number generator on my computer. That's chaotic. 621 00:32:46,000 --> 00:32:48,040 Speaker 1: No, you're you're being persnickety about it, but in a 622 00:32:48,120 --> 00:32:52,600 Speaker 1: really actually fascinating way that quantum theorists get really nerdy 623 00:32:52,600 --> 00:32:54,000 Speaker 1: about it. We're going to talk about that later on. 624 00:32:54,080 --> 00:32:57,360 Speaker 1: People use like lava lamps and cosmic rays to try 625 00:32:57,360 --> 00:32:59,440 Speaker 1: to be like really truly random to make sure they're 626 00:32:59,440 --> 00:33:02,640 Speaker 1: not being like you're influenced by something, because that randomness 627 00:33:02,680 --> 00:33:05,160 Speaker 1: is absolutely essential for this whole argument. So we're going 628 00:33:05,240 --> 00:33:07,040 Speaker 1: to come back to that point. Okay, and it's going 629 00:33:07,040 --> 00:33:09,720 Speaker 1: to involve like scripts of Gilligan's Island. It's really weird. 630 00:33:10,480 --> 00:33:12,720 Speaker 2: That's great. I was hoping that's where this episode would 631 00:33:12,800 --> 00:33:13,080 Speaker 2: end up. 632 00:33:14,160 --> 00:33:16,680 Speaker 1: All Right, So we each have an electron, and we 633 00:33:16,720 --> 00:33:19,520 Speaker 1: each have three axes, and we randomly pick which axis 634 00:33:19,560 --> 00:33:22,800 Speaker 1: we're going to measure this electron on. Right, So imagine 635 00:33:22,800 --> 00:33:26,240 Speaker 1: that these things actually are determined, that some hidden variable 636 00:33:26,280 --> 00:33:29,160 Speaker 1: on this electron makes mine be up and yours be 637 00:33:29,240 --> 00:33:31,880 Speaker 1: down along some axis. Right, it's not random, it's not 638 00:33:32,000 --> 00:33:35,600 Speaker 1: quantum mechanical. Let's imagine that hidden variables are really at 639 00:33:35,600 --> 00:33:38,400 Speaker 1: work here. Well, then what would happen? Well, it's all 640 00:33:38,440 --> 00:33:41,440 Speaker 1: determined in advance, right, I have my three axes, I 641 00:33:41,440 --> 00:33:44,120 Speaker 1: have my particle, You have your particle. But my particle 642 00:33:44,160 --> 00:33:46,320 Speaker 1: is actually pointing in some direction. Your particle is pointing 643 00:33:46,400 --> 00:33:49,680 Speaker 1: in some direction. And so it's all determined in advance, 644 00:33:49,760 --> 00:33:53,040 Speaker 1: and you can actually enumerate all the possibilities. Right, And 645 00:33:53,120 --> 00:33:56,000 Speaker 1: we have three axes, and so one third of the 646 00:33:56,080 --> 00:33:58,880 Speaker 1: time we're going to be choosing the same axis, right, 647 00:33:58,960 --> 00:34:01,400 Speaker 1: Like if I choose Z, you're gonna choose Z. Because 648 00:34:01,400 --> 00:34:03,440 Speaker 1: we have three axes and we're both choosing randomly, So 649 00:34:03,680 --> 00:34:06,000 Speaker 1: a third of the time we choose the same axis, 650 00:34:06,280 --> 00:34:09,239 Speaker 1: which means they will get the opposite results, Like we'll 651 00:34:09,320 --> 00:34:11,879 Speaker 1: choose the same axis, I'll get up and you'll get down. Right, 652 00:34:12,400 --> 00:34:14,640 Speaker 1: So at least a third of the time we get 653 00:34:14,680 --> 00:34:18,400 Speaker 1: the opposite results, which means that we get the same 654 00:34:18,480 --> 00:34:22,640 Speaker 1: result less than two thirds of the time, right, Okay, 655 00:34:22,880 --> 00:34:25,960 Speaker 1: So that's what we expect for hidden variables, and that 656 00:34:26,280 --> 00:34:30,400 Speaker 1: just comes out of having three axes and choosing them randomly. Okay, 657 00:34:30,520 --> 00:34:33,080 Speaker 1: So what if there aren't hidden variables? So what if 658 00:34:33,080 --> 00:34:34,839 Speaker 1: there's quantum mechanics going on? 659 00:34:35,239 --> 00:34:35,439 Speaker 6: Gas? 660 00:34:36,560 --> 00:34:40,600 Speaker 1: Okay, So what happens if this quantum mechanics going on? 661 00:34:41,000 --> 00:34:43,560 Speaker 1: So if there's no hidden variables, if quantum mechanics is 662 00:34:43,600 --> 00:34:47,080 Speaker 1: at play, then there's something sneaky going on here, which 663 00:34:47,160 --> 00:34:50,719 Speaker 1: is that then Heisenberg uncertainty principles sneaks in the door. 664 00:34:51,360 --> 00:34:55,000 Speaker 1: Heisenberg says that there's some things you can't know simultaneously 665 00:34:55,040 --> 00:34:58,000 Speaker 1: about the universe, like you can't know the speed and 666 00:34:58,040 --> 00:35:01,239 Speaker 1: the location of a particle at the same time. Right, Well, 667 00:35:01,280 --> 00:35:05,920 Speaker 1: it also applies to spins of a particle in different directions. So, 668 00:35:06,040 --> 00:35:08,400 Speaker 1: for example, if I measure the spin of a particle 669 00:35:08,400 --> 00:35:10,840 Speaker 1: in one axis, I can't know it in the other ones, 670 00:35:11,400 --> 00:35:13,160 Speaker 1: or if I measure it in some access, I can't 671 00:35:13,160 --> 00:35:15,719 Speaker 1: know it on my first one. So there is no 672 00:35:16,160 --> 00:35:20,520 Speaker 1: true spin direction of these particles in the quantum mechanical view. Right, 673 00:35:20,840 --> 00:35:23,000 Speaker 1: It's not like there is a true spin and we're 674 00:35:23,040 --> 00:35:25,560 Speaker 1: measuring along some axis, so we get up or down. 675 00:35:26,000 --> 00:35:29,080 Speaker 1: It's like scrambled in this weird way. And in the 676 00:35:29,120 --> 00:35:32,600 Speaker 1: quantum mechanical view, you represent the probability of these particles 677 00:35:32,600 --> 00:35:36,080 Speaker 1: being spin up or spin down using these complex numbers. 678 00:35:36,120 --> 00:35:38,480 Speaker 1: It comes out of the shortening your equation, and it's 679 00:35:38,520 --> 00:35:43,080 Speaker 1: all determined by these complex amplitudes. And like in many 680 00:35:43,160 --> 00:35:46,600 Speaker 1: quantum effects, these complex amplitudes can interfere with each other, 681 00:35:47,080 --> 00:35:50,080 Speaker 1: and so quantum mechanics allows these particles to interfere with 682 00:35:50,120 --> 00:35:52,200 Speaker 1: each other. It's not like all set up in advance. 683 00:35:52,480 --> 00:35:57,200 Speaker 1: They dynamically respond to the situation, and quantum mechanics predicts 684 00:35:57,360 --> 00:36:00,799 Speaker 1: that you should get the same spin around three reforths 685 00:36:00,800 --> 00:36:03,920 Speaker 1: of the time. Now remember the hidden variables prediction says 686 00:36:04,160 --> 00:36:06,879 Speaker 1: you cannot get the same spin more than two thirds 687 00:36:06,920 --> 00:36:10,160 Speaker 1: at the time. Absolutely not totally impossible. That would break 688 00:36:10,239 --> 00:36:14,360 Speaker 1: logic quantum mechanics says no, no, no, at these weird angles, 689 00:36:14,920 --> 00:36:17,000 Speaker 1: then three fourths of the time you can get the 690 00:36:17,040 --> 00:36:19,320 Speaker 1: same spin. If you arrange things right, depending on the 691 00:36:19,360 --> 00:36:21,920 Speaker 1: angles between your axes, you can get the same spin 692 00:36:22,280 --> 00:36:24,520 Speaker 1: more than two thirds of the time, up to three 693 00:36:24,640 --> 00:36:25,560 Speaker 1: fourths of the time. 694 00:36:25,960 --> 00:36:29,680 Speaker 2: Okay, so I was totally following you, but adding the 695 00:36:29,719 --> 00:36:33,160 Speaker 2: Heisenberg uncertainty principle feels like cheating because I don't really 696 00:36:33,200 --> 00:36:35,960 Speaker 2: understand why that works. And it's like, okay, but also 697 00:36:36,040 --> 00:36:37,919 Speaker 2: now we're playing by a totally different set of rules 698 00:36:37,920 --> 00:36:40,360 Speaker 2: that you don't understand, and it makes sense. So could 699 00:36:40,360 --> 00:36:44,560 Speaker 2: we take a quick break and talk about Heisenberg uncertainty 700 00:36:44,560 --> 00:36:45,520 Speaker 2: principle just for a second? 701 00:36:45,719 --> 00:36:48,840 Speaker 1: Yeah? Sure. So you know, Heisenberg un certainty principle is 702 00:36:48,920 --> 00:36:51,240 Speaker 1: just a way of thinking about the spread of possible 703 00:36:51,280 --> 00:36:56,200 Speaker 1: outcomes and what's allowed, and the fact that measurements are connected, 704 00:36:56,200 --> 00:36:58,960 Speaker 1: that you can't measure one thing independently, put that in 705 00:36:59,000 --> 00:37:01,400 Speaker 1: the box, know it, and then move on to measure 706 00:37:01,440 --> 00:37:03,759 Speaker 1: something else. It's just a way of thinking about how 707 00:37:03,880 --> 00:37:06,839 Speaker 1: like the truth isn't totally determined, and so in that way, 708 00:37:06,840 --> 00:37:09,240 Speaker 1: it's kind of a shorthand. We can actually do without 709 00:37:09,280 --> 00:37:12,560 Speaker 1: introducing the Heisenberg un certainty principle entirely, if we can 710 00:37:12,640 --> 00:37:15,840 Speaker 1: just think about the nature of quantum measurements, and so 711 00:37:16,000 --> 00:37:18,240 Speaker 1: really all you need to know is that the quantum 712 00:37:18,239 --> 00:37:22,640 Speaker 1: mechanical prediction for whether my California particle is spin up 713 00:37:22,800 --> 00:37:26,480 Speaker 1: or spin down along some axis is probabilistic, right, that's 714 00:37:26,480 --> 00:37:28,840 Speaker 1: the quantum mechanical nature of it. It predicts some probability 715 00:37:28,840 --> 00:37:31,200 Speaker 1: of this and some probability of that, and yours it 716 00:37:31,200 --> 00:37:33,480 Speaker 1: predicts the opposite. And that's very simple. But if you 717 00:37:33,600 --> 00:37:36,279 Speaker 1: rotate your axis so you're not measuring along the same 718 00:37:36,320 --> 00:37:39,839 Speaker 1: axis as I am, there's a relationship between those probabilities. 719 00:37:40,040 --> 00:37:43,279 Speaker 1: But that relationship is different in the quantum version than 720 00:37:43,360 --> 00:37:47,040 Speaker 1: in the hidden variables version, because we have these amplitudes, 721 00:37:47,239 --> 00:37:50,360 Speaker 1: because we have these complex numbers that are interfering with 722 00:37:50,440 --> 00:37:54,560 Speaker 1: each other. And Bell realized that as that rotates, the 723 00:37:54,640 --> 00:37:57,799 Speaker 1: number changes differently for the quantum version than it does 724 00:37:57,880 --> 00:38:01,400 Speaker 1: for the true everything is determined hidden variables version. And 725 00:38:01,440 --> 00:38:04,080 Speaker 1: it's because of those complex amplitudes and the way that 726 00:38:04,120 --> 00:38:08,240 Speaker 1: calculation happens. And it's really fascinating because normally these complex 727 00:38:08,239 --> 00:38:12,600 Speaker 1: amplitudes aren't things that you can see, but when there's interference, 728 00:38:12,760 --> 00:38:14,759 Speaker 1: then those results are apparent. It's sort of like in 729 00:38:14,800 --> 00:38:18,080 Speaker 1: the double slit experiment. You can't see the probabilities, but 730 00:38:18,120 --> 00:38:20,759 Speaker 1: you can see them interfering with each other. And so 731 00:38:21,200 --> 00:38:24,120 Speaker 1: that's roughly what's happening here, is that the probability of 732 00:38:24,120 --> 00:38:26,800 Speaker 1: measuring along one axis is interfering with the probability of 733 00:38:26,800 --> 00:38:29,399 Speaker 1: measuring along a different axis in a way that gives 734 00:38:29,440 --> 00:38:32,840 Speaker 1: us a different dependence as the angle changes, and so 735 00:38:32,880 --> 00:38:36,040 Speaker 1: that comes up with a different prediction. And that's why 736 00:38:36,120 --> 00:38:38,680 Speaker 1: it's not an individual experiment. You're like, I ran it, 737 00:38:38,880 --> 00:38:41,000 Speaker 1: I got up and down, and therefore kronme mechanics is 738 00:38:41,000 --> 00:38:43,239 Speaker 1: correct and hidden variables is wrong. It's like I ran 739 00:38:43,280 --> 00:38:46,560 Speaker 1: it a thousand times and I got the same direction 740 00:38:46,680 --> 00:38:49,640 Speaker 1: for both particles seventy two percent of the time, which 741 00:38:49,680 --> 00:38:52,719 Speaker 1: is impossible in the hidden variables theory. So it's an 742 00:38:52,760 --> 00:38:54,440 Speaker 1: average over many experiments. 743 00:38:54,719 --> 00:38:56,879 Speaker 2: Okay, so at the end of this experiment we can 744 00:38:56,920 --> 00:39:01,640 Speaker 2: say that what's happening is definitely random, not chaotic. Yeah, 745 00:39:01,640 --> 00:39:04,040 Speaker 2: and so there are no hidden variables. 746 00:39:04,200 --> 00:39:07,359 Speaker 1: That's right, and it's incredibly powerful and broad result. It's 747 00:39:07,400 --> 00:39:11,040 Speaker 1: saying it cannot be a hidden variable. Right, you don't 748 00:39:11,080 --> 00:39:12,840 Speaker 1: even have to know what the hidden variable is. You 749 00:39:12,880 --> 00:39:16,160 Speaker 1: can imagine some like additional dimension of space, and these 750 00:39:16,200 --> 00:39:19,080 Speaker 1: particles have some features in that space, and that's what's 751 00:39:19,120 --> 00:39:22,280 Speaker 1: determining it. No, we don't even have to discover those dimensions. 752 00:39:22,320 --> 00:39:26,120 Speaker 1: This proves that that cannot be happening. No hidden variable 753 00:39:26,160 --> 00:39:31,760 Speaker 1: theory satisfies these experiments. It's really incredible. The consequences are huge. 754 00:39:32,160 --> 00:39:36,160 Speaker 1: But there's a very important caveat right. We've been talking 755 00:39:36,160 --> 00:39:39,760 Speaker 1: about hidden variables, and Bell's experiment actually only rules out 756 00:39:40,160 --> 00:39:44,640 Speaker 1: local hidden variables. Information that's like connected to the particle 757 00:39:44,680 --> 00:39:47,000 Speaker 1: that like a little detailed that like the electron has 758 00:39:47,040 --> 00:39:49,560 Speaker 1: tucked to do its pocket. That's determining whether it's going 759 00:39:49,640 --> 00:39:53,279 Speaker 1: to be plus or minus. Right, local hidden variables. And 760 00:39:53,320 --> 00:39:56,239 Speaker 1: this was actually misunderstood for decades. 761 00:39:56,480 --> 00:39:58,440 Speaker 2: And when we get back from the break, we'll find 762 00:39:58,440 --> 00:40:01,400 Speaker 2: out why the answer was a scured for so long. 763 00:40:22,239 --> 00:40:26,480 Speaker 2: All Right, we're back, and Bell's experiments were misunderstood for decades, 764 00:40:26,520 --> 00:40:28,200 Speaker 2: and Daniel's going to explain to us why. 765 00:40:29,520 --> 00:40:32,600 Speaker 1: So. This very smart guy, John von Neumann, he's like 766 00:40:32,880 --> 00:40:35,440 Speaker 1: widely considered one of the smartest dudes in history and 767 00:40:35,520 --> 00:40:39,400 Speaker 1: he's the guy who showed that Heisenberg's matrix quantum mechanics 768 00:40:39,480 --> 00:40:43,640 Speaker 1: was the same thing mathematically as Schrodinger's wave quantum mechanics, 769 00:40:43,920 --> 00:40:46,759 Speaker 1: even though those two guys hated each other really like 770 00:40:46,800 --> 00:40:49,919 Speaker 1: a towering figure. And he did this proof, this conceptual proof, 771 00:40:49,960 --> 00:40:53,960 Speaker 1: before Bell's experiments that showed that quantum mechanics couldn't have 772 00:40:54,000 --> 00:40:57,200 Speaker 1: any hidden variables at all. But it turns out there 773 00:40:57,280 --> 00:40:59,680 Speaker 1: was a mistake in it, and people actually argue about 774 00:40:59,719 --> 00:41:02,960 Speaker 1: like was it von Neuman's mistake or did people misinterpret 775 00:41:02,960 --> 00:41:05,200 Speaker 1: what von Neuman was saying and he really understood it. 776 00:41:05,320 --> 00:41:08,719 Speaker 1: They don't like pointing out mistakes in genius's work. But 777 00:41:09,040 --> 00:41:11,640 Speaker 1: for a long time, the lore was that quantum mechanics 778 00:41:11,719 --> 00:41:14,839 Speaker 1: was inconsistent with any kind of hidden variable. And it 779 00:41:14,880 --> 00:41:17,680 Speaker 1: was Bell who came up with these experiments that showed 780 00:41:18,000 --> 00:41:21,319 Speaker 1: actually what they do is they show no local hidden variables. 781 00:41:21,840 --> 00:41:25,120 Speaker 1: His experiments can't disprove a different kind of hidden variables, 782 00:41:25,360 --> 00:41:29,840 Speaker 1: non local right like global hidden variables. And as a result, 783 00:41:29,840 --> 00:41:33,160 Speaker 1: they're like interpretations of quantum mechanics like bomy and mechanics 784 00:41:33,480 --> 00:41:37,239 Speaker 1: that have these like global guiding functions. This pilot wave 785 00:41:37,360 --> 00:41:39,880 Speaker 1: that like tells this particle to go positive in that 786 00:41:39,960 --> 00:41:42,920 Speaker 1: particle to go negative. So they are deterministic, but they 787 00:41:42,960 --> 00:41:47,400 Speaker 1: required this like weird non local coordination between all the 788 00:41:47,400 --> 00:41:50,880 Speaker 1: particles and the universe in a strange way. That's very counterintuitive. 789 00:41:51,520 --> 00:41:54,440 Speaker 1: But the big picture result for Bell's experiment is not 790 00:41:54,520 --> 00:41:57,600 Speaker 1: that it shows no hidden variables, but no local hidden variables, 791 00:41:57,880 --> 00:42:03,440 Speaker 1: which means that quantum mechanics is weirdly non local. Right, Like, 792 00:42:03,800 --> 00:42:06,920 Speaker 1: what's happening here is my particle is collapsing and your 793 00:42:06,920 --> 00:42:10,799 Speaker 1: particle is collapsing at the same time. It's instantaneous across 794 00:42:10,920 --> 00:42:15,120 Speaker 1: time and space. Quantum mechanics is non local. 795 00:42:15,480 --> 00:42:21,320 Speaker 2: Okay, So Bell proved that there was no local hidden variable. Yeah, 796 00:42:21,360 --> 00:42:26,160 Speaker 2: but did we ever convince ourselves that there's no Bomian 797 00:42:26,560 --> 00:42:30,640 Speaker 2: global guiding function or could That's still an open question. 798 00:42:30,880 --> 00:42:33,560 Speaker 1: That's still an open question that these Bell's experiments can't 799 00:42:33,600 --> 00:42:37,319 Speaker 1: tell us whether Bomian mechanics is correct and there are 800 00:42:37,400 --> 00:42:41,000 Speaker 1: hidden variables but they're global, or there are no hidden 801 00:42:41,040 --> 00:42:45,359 Speaker 1: variables at all. Right, So people often interpret Bell's experiments 802 00:42:45,440 --> 00:42:47,839 Speaker 1: too broadly. They say, well, there's no hidden variables, but 803 00:42:47,920 --> 00:42:50,359 Speaker 1: actually they just show no local hidden variables. So if 804 00:42:50,360 --> 00:42:53,560 Speaker 1: your theory has like weird global hidden variables, yeah, that's 805 00:42:53,560 --> 00:42:56,919 Speaker 1: still cool. And that's what Bomian mechanics is. And Bell 806 00:42:57,080 --> 00:43:00,560 Speaker 1: actually was a strong proponent of hidden variable right. He 807 00:43:00,719 --> 00:43:03,800 Speaker 1: thought the global hidden variables were the way the universe worked. 808 00:43:04,000 --> 00:43:06,640 Speaker 1: So it's sort of weird because he's like famous for 809 00:43:06,719 --> 00:43:09,239 Speaker 1: devolishing hidden variables, but he actually believed in them. But 810 00:43:09,280 --> 00:43:12,120 Speaker 1: he believed in the global version of it. And people 811 00:43:12,120 --> 00:43:15,200 Speaker 1: have actually done these experiments. These are not just thought experiments. 812 00:43:15,280 --> 00:43:18,319 Speaker 1: The first ones were done in the seventies, and then 813 00:43:18,480 --> 00:43:20,920 Speaker 1: they do them in fancier and fancier ways, and they 814 00:43:21,000 --> 00:43:23,759 Speaker 1: keep the particles further and further apart to test this 815 00:43:23,840 --> 00:43:27,560 Speaker 1: question of like is this really happening instantaneously across time 816 00:43:27,680 --> 00:43:29,960 Speaker 1: and space. And the way they do this is they 817 00:43:30,280 --> 00:43:33,239 Speaker 1: entangle the particles and they really do separate them in 818 00:43:33,480 --> 00:43:36,840 Speaker 1: vast macroscopic distances and then make their measurements at the 819 00:43:36,880 --> 00:43:39,799 Speaker 1: same time. So there's not enough time for light to 820 00:43:39,840 --> 00:43:43,600 Speaker 1: go from like California to Virginia to inform my California 821 00:43:43,640 --> 00:43:46,840 Speaker 1: particle what happened to your Virginia particle, So we know 822 00:43:46,920 --> 00:43:49,760 Speaker 1: that this really does have to happen at the same time. 823 00:43:50,160 --> 00:43:53,640 Speaker 2: Well, wouldn't that have to mean that the information is 824 00:43:53,680 --> 00:43:54,799 Speaker 2: traveling faster than light? 825 00:43:55,239 --> 00:43:57,480 Speaker 1: Yeah? And so this was a question from a listener 826 00:43:57,480 --> 00:44:00,840 Speaker 1: who wrote in and asked something similar. Here's Mohammad asking 827 00:44:00,840 --> 00:44:01,719 Speaker 1: his question. 828 00:44:01,880 --> 00:44:05,080 Speaker 7: Hi, Kelly and Daniel, I would like to understand that 829 00:44:05,160 --> 00:44:08,040 Speaker 7: if information travels have the speed of light, then how 830 00:44:08,080 --> 00:44:11,520 Speaker 7: do we know that quantum entanglement is instantaneous? How do 831 00:44:11,600 --> 00:44:14,440 Speaker 7: we know that the particles and suence each the faster 832 00:44:14,520 --> 00:44:17,040 Speaker 7: than the speed of light when the measurement itself is 833 00:44:17,080 --> 00:44:19,600 Speaker 7: captive the speed of flight? How can we measure them 834 00:44:19,640 --> 00:44:23,280 Speaker 7: precisely at the same time When the particles have moved 835 00:44:23,400 --> 00:44:28,120 Speaker 7: far apart after they untangled, they are subjected to change 836 00:44:28,160 --> 00:44:31,520 Speaker 7: in gravitational field. And that seems to me like it 837 00:44:31,600 --> 00:44:34,000 Speaker 7: is enough to throw it forthing out of whack. So 838 00:44:34,360 --> 00:44:37,520 Speaker 7: what kind of witchcraft allows us to technolo gr all right? 839 00:44:37,520 --> 00:44:39,640 Speaker 1: And so yeah, Muhammad is asking, how do we know 840 00:44:39,680 --> 00:44:42,120 Speaker 1: as faster than light? And Kelly is asking, doesn't that 841 00:44:42,239 --> 00:44:47,600 Speaker 1: violate everything I thought I know about physics? And so 842 00:44:47,800 --> 00:44:50,080 Speaker 1: to answer Mohammed's question, what they do is they bring 843 00:44:50,160 --> 00:44:52,680 Speaker 1: these things really far apart and they make them measurement 844 00:44:52,960 --> 00:44:56,160 Speaker 1: as simultaneously as they can. So if they know they 845 00:44:56,200 --> 00:44:59,080 Speaker 1: make the measurement within a microsecond, then as long as 846 00:44:59,120 --> 00:45:03,160 Speaker 1: there further a part than a light microsecond, further part 847 00:45:03,200 --> 00:45:05,960 Speaker 1: than light can go in a microsecond, then they know 848 00:45:06,080 --> 00:45:08,200 Speaker 1: that the collapse is faster than light. You can't prove 849 00:45:08,239 --> 00:45:11,520 Speaker 1: it's literally instantaneous, but you can prove that it's faster 850 00:45:11,600 --> 00:45:15,400 Speaker 1: than light because the particles are separated by more distance 851 00:45:15,480 --> 00:45:18,319 Speaker 1: than light could go in the intervening time. And so 852 00:45:18,360 --> 00:45:21,080 Speaker 1: how does that not violate relativity? Well, relativity tells us 853 00:45:21,080 --> 00:45:24,720 Speaker 1: no information can be transmitted from California to Virginia faster 854 00:45:24,760 --> 00:45:28,399 Speaker 1: than light, but no information is being transmitted. Like if 855 00:45:28,440 --> 00:45:32,400 Speaker 1: I measure my particle and it goes from undetermined to up, 856 00:45:32,840 --> 00:45:35,759 Speaker 1: then Kelly's particle goes from undetermined to down. But she 857 00:45:35,800 --> 00:45:38,719 Speaker 1: doesn't know that there's no information she's gathered there. She 858 00:45:38,800 --> 00:45:41,520 Speaker 1: just has her particle she hasn't measured yet. When she 859 00:45:41,560 --> 00:45:44,000 Speaker 1: goes to measure it, she sees, oh, it's down. She 860 00:45:44,080 --> 00:45:47,480 Speaker 1: doesn't know whether it was collapsed or not. People often 861 00:45:47,480 --> 00:45:50,560 Speaker 1: write in and they're like, what if Daniel collapses his particle, 862 00:45:50,560 --> 00:45:53,120 Speaker 1: then Kelly can see that it's collapsed, and that's a 863 00:45:53,120 --> 00:45:55,680 Speaker 1: way to communicate information faster than light. But Kelly has 864 00:45:55,719 --> 00:45:58,840 Speaker 1: no way to know whether her particle is collapsed or not. 865 00:45:58,920 --> 00:46:00,880 Speaker 1: All she can do is measure and say, oh, I 866 00:46:00,920 --> 00:46:03,719 Speaker 1: got a minus. She doesn't know she's collapsing it to 867 00:46:03,760 --> 00:46:07,359 Speaker 1: get that minus, or if it was already collapsed. So, yes, 868 00:46:07,360 --> 00:46:10,520 Speaker 1: the quantum wave function is non local. It extends from 869 00:46:10,560 --> 00:46:15,520 Speaker 1: California to Virginia and collapses simultaneously across space, which is 870 00:46:15,560 --> 00:46:18,640 Speaker 1: really weird. But you can't use it to transmit any 871 00:46:18,719 --> 00:46:22,560 Speaker 1: information from California to Virginia faster than light, and so 872 00:46:22,640 --> 00:46:26,040 Speaker 1: it doesn't break special relativity, which feels like a really 873 00:46:26,120 --> 00:46:28,800 Speaker 1: loyally loophole, but it's true. 874 00:46:29,000 --> 00:46:32,840 Speaker 2: All right. Alright, let's clear up Kelly's misconception here. So 875 00:46:33,080 --> 00:46:36,480 Speaker 2: my first thought was, well, the information between those two 876 00:46:36,480 --> 00:46:41,080 Speaker 2: electrons has already been transmitted when they were entangled, and 877 00:46:41,120 --> 00:46:45,680 Speaker 2: so no information is being transmitted when one is actually 878 00:46:45,719 --> 00:46:49,600 Speaker 2: observed because they already were tied. But they don't know 879 00:46:49,600 --> 00:46:52,200 Speaker 2: if they're up or down yet until they're observed, and 880 00:46:52,239 --> 00:46:54,600 Speaker 2: so there is Okay, I get it. 881 00:46:54,800 --> 00:46:58,120 Speaker 1: That's really insightful. Yeah, So what's happening when you're entangling 882 00:46:58,120 --> 00:47:01,160 Speaker 1: them is you're removing some possibilities, right, You're removing the 883 00:47:01,280 --> 00:47:04,000 Speaker 1: up up and the down down possibilities. You're only leaving 884 00:47:04,040 --> 00:47:07,840 Speaker 1: the up down and the down up. However, we're leaving 885 00:47:07,840 --> 00:47:11,600 Speaker 1: those possibilities undetermined. And so when I make my measurement, 886 00:47:11,840 --> 00:47:14,359 Speaker 1: it crosses one more off your list, leaving you with 887 00:47:14,480 --> 00:47:18,560 Speaker 1: only one possibility. So that is happening across space and time. 888 00:47:18,600 --> 00:47:22,040 Speaker 1: But you're right, the entanglement itself is local, and it 889 00:47:22,120 --> 00:47:25,320 Speaker 1: was made when the particles were created in these initial states. 890 00:47:28,440 --> 00:47:31,440 Speaker 3: Hey, Daniel and Kelly, this is Matt. You may remember 891 00:47:31,480 --> 00:47:35,120 Speaker 3: me from editing audio on your show. I was in 892 00:47:35,160 --> 00:47:38,480 Speaker 3: the middle of editing this episode when some of this 893 00:47:38,560 --> 00:47:42,240 Speaker 3: stuff that Daniel was saying started to hurt my brain 894 00:47:42,719 --> 00:47:45,839 Speaker 3: much in the way seemingly that it hurt Kelly's brain. 895 00:47:46,600 --> 00:47:49,600 Speaker 3: And I have a question for you. One thing in 896 00:47:49,640 --> 00:47:53,560 Speaker 3: particular that I'm having an especially hard time understanding is 897 00:47:53,760 --> 00:47:58,960 Speaker 3: the observational element of quantum physics. How and why does 898 00:47:59,000 --> 00:48:01,600 Speaker 3: it matter if the state of a particle is or 899 00:48:01,680 --> 00:48:06,680 Speaker 3: isn't being observed. Do quantum particles have awareness? Are they shy? 900 00:48:06,719 --> 00:48:11,680 Speaker 3: What is it about observation that determines or sets a 901 00:48:11,760 --> 00:48:16,040 Speaker 3: quantum object in place, so to speak. Doesn't this mean 902 00:48:16,080 --> 00:48:20,520 Speaker 3: that consciousness is somehow related to the state of things, 903 00:48:20,760 --> 00:48:26,480 Speaker 3: that consciousness somehow dictates or influences reality, And if so, 904 00:48:26,760 --> 00:48:30,720 Speaker 3: doesn't this indirectly mean that before consciousness evolved in the universe, 905 00:48:31,040 --> 00:48:34,000 Speaker 3: the universe didn't fully exist. If you could shed some 906 00:48:34,120 --> 00:48:36,640 Speaker 3: light on this matter, I'd really appreciate it, But I'm 907 00:48:36,640 --> 00:48:40,000 Speaker 3: fully prepared to be confused about this for the rest 908 00:48:40,000 --> 00:48:40,560 Speaker 3: of my life. 909 00:48:41,160 --> 00:48:48,160 Speaker 1: Thanks. All right, great question, Matt. So First, remember that 910 00:48:48,280 --> 00:48:52,600 Speaker 1: observation is not passive. It's active. It requires some kind 911 00:48:52,640 --> 00:48:55,640 Speaker 1: of interaction with the thing you're studying. You want to 912 00:48:55,680 --> 00:48:58,360 Speaker 1: see a particle, you have to bounce a photon a 913 00:48:58,480 --> 00:49:01,439 Speaker 1: probe off of it in order to see where it is. 914 00:49:01,840 --> 00:49:04,000 Speaker 1: You want to measure the spin of your electron, you 915 00:49:04,040 --> 00:49:06,280 Speaker 1: have to put it through a magnetic field that acts 916 00:49:06,320 --> 00:49:11,759 Speaker 1: like a probe and interacts with it. So observation requires interaction. Now, 917 00:49:11,800 --> 00:49:16,240 Speaker 1: if that interaction yields information, that means that your probe 918 00:49:16,280 --> 00:49:19,239 Speaker 1: is now entangled with the system. That's because if the 919 00:49:19,239 --> 00:49:23,480 Speaker 1: way your probe particle behaves afterwards depends on the electron spin, 920 00:49:23,880 --> 00:49:26,719 Speaker 1: then your probe is entangled with the quantum system because 921 00:49:26,760 --> 00:49:29,960 Speaker 1: the spin of the electron determines what the probe does. 922 00:49:30,440 --> 00:49:33,920 Speaker 1: So now your probe is part of the system. But if, 923 00:49:33,960 --> 00:49:36,680 Speaker 1: for example, your probe was badly designed so it doesn't 924 00:49:36,719 --> 00:49:39,759 Speaker 1: depend on the electron spin, it doesn't extract information, then 925 00:49:39,800 --> 00:49:43,440 Speaker 1: it's decoupled and it's not entangled. So it's not about 926 00:49:43,480 --> 00:49:46,680 Speaker 1: consciousness or shyness. It's about interacting in a way that 927 00:49:46,760 --> 00:49:50,520 Speaker 1: yields information about the state of the system. Now, whether 928 00:49:50,560 --> 00:49:53,720 Speaker 1: there's like wave function collapse or not is another question 929 00:49:53,880 --> 00:49:58,720 Speaker 1: of philosophy. Copenhagen interpretation says interaction collapses the wave function 930 00:49:58,920 --> 00:50:02,239 Speaker 1: if one of the object involved is classical, like if 931 00:50:02,280 --> 00:50:05,960 Speaker 1: the probe is classical, But it also doesn't define what 932 00:50:06,080 --> 00:50:09,840 Speaker 1: classical means and why quantum objects, when they come together, 933 00:50:09,960 --> 00:50:14,640 Speaker 1: somehow become classical. The major alternative many world hypothesis says 934 00:50:14,640 --> 00:50:17,759 Speaker 1: the interaction entangles you and you become part of the system. 935 00:50:17,840 --> 00:50:20,680 Speaker 1: So now you only see one outcome. This no collapse, 936 00:50:21,000 --> 00:50:24,120 Speaker 1: You're just along one of the branches. But philosophically, the 937 00:50:24,160 --> 00:50:26,960 Speaker 1: whole thing is kind of a mess. All right, great question, 938 00:50:27,080 --> 00:50:29,880 Speaker 1: But Kelly, let's go back to your other fun loophole, 939 00:50:30,080 --> 00:50:35,000 Speaker 1: which is this experiment requires people to choose axes at 940 00:50:35,160 --> 00:50:39,080 Speaker 1: random and then measure how often something happens over a 941 00:50:39,120 --> 00:50:41,160 Speaker 1: bunch of random trials. How do we know that those 942 00:50:41,200 --> 00:50:43,880 Speaker 1: are random? Or testing randomness? It relies on randomness? Is 943 00:50:43,880 --> 00:50:47,520 Speaker 1: there some circularity? There are we on firm ground? And 944 00:50:47,600 --> 00:50:51,040 Speaker 1: there's a really fun kind of paranoid theory of quantum 945 00:50:51,080 --> 00:50:55,680 Speaker 1: mechanics called super determinism, and it says, look, the outcome 946 00:50:55,719 --> 00:50:58,239 Speaker 1: of these experiments relies on those things being random. But 947 00:50:58,280 --> 00:51:00,919 Speaker 1: what if they weren't. What if Kelly and Dana were 948 00:51:00,920 --> 00:51:06,400 Speaker 1: manipulated somehow into choosing axes that give this result, right, 949 00:51:06,440 --> 00:51:08,600 Speaker 1: Because if they're not random, then the result can't be 950 00:51:08,680 --> 00:51:11,520 Speaker 1: relied on. And you know what if it all is 951 00:51:11,560 --> 00:51:14,440 Speaker 1: actually determined by something that happened a billion years ago 952 00:51:14,560 --> 00:51:17,359 Speaker 1: and set this series in motion. And so to try 953 00:51:17,400 --> 00:51:20,120 Speaker 1: to get around this loophole, they've done really hilarious things, 954 00:51:20,160 --> 00:51:24,200 Speaker 1: like they've made the choice super duper chaotic, Like they 955 00:51:24,280 --> 00:51:28,160 Speaker 1: randomly sample scripts from television shows and you know, like 956 00:51:28,520 --> 00:51:31,200 Speaker 1: if the letter is greater than K, then they choose 957 00:51:31,280 --> 00:51:33,239 Speaker 1: this axis and if it's less than G, you know, 958 00:51:33,320 --> 00:51:35,680 Speaker 1: on the third line of page two, this kind of stuff, 959 00:51:35,960 --> 00:51:39,520 Speaker 1: and they combine it with lava lamps and cosmic rays 960 00:51:39,600 --> 00:51:42,239 Speaker 1: to try to get like as random as possible. But 961 00:51:42,280 --> 00:51:44,960 Speaker 1: in the end, superdeterminism is something you can never really 962 00:51:45,080 --> 00:51:49,480 Speaker 1: totally knock down, because there's always some crazy paranoid theory 963 00:51:49,480 --> 00:51:52,000 Speaker 1: you could have that these things are just being like 964 00:51:52,160 --> 00:51:56,840 Speaker 1: orchestrated by folks in the simulation or super intelligent aliens 965 00:51:56,960 --> 00:51:57,480 Speaker 1: or something. 966 00:52:00,120 --> 00:52:03,640 Speaker 2: All of our best efforts at getting random numbers say 967 00:52:03,680 --> 00:52:05,760 Speaker 2: the same thing that Bell's experiment works. 968 00:52:06,080 --> 00:52:09,440 Speaker 1: Yeah, okay, yeah, And so broadly the consensus in the 969 00:52:09,440 --> 00:52:13,000 Speaker 1: community is, yes, the universe really is random at the 970 00:52:13,040 --> 00:52:17,600 Speaker 1: microscopic level, really is undetermined, and these extraordinarily subtle but 971 00:52:17,760 --> 00:52:21,440 Speaker 1: very clever experiments reveal that that's how the universe works 972 00:52:21,520 --> 00:52:24,160 Speaker 1: at the lowest level. And it relies not just on 973 00:52:24,280 --> 00:52:28,279 Speaker 1: the universe being random and the results being undetermined, but 974 00:52:28,520 --> 00:52:31,040 Speaker 1: having these tests with particles that are distant from each 975 00:52:31,040 --> 00:52:34,359 Speaker 1: other yet quantum mechanically having their fates connected to each other. 976 00:52:34,800 --> 00:52:37,719 Speaker 2: Okay, and so now nobody should ever be confused again 977 00:52:37,760 --> 00:52:39,000 Speaker 2: about entangled particles. 978 00:52:40,880 --> 00:52:42,600 Speaker 1: This stuff entangles your brain for. 979 00:52:42,560 --> 00:52:45,560 Speaker 2: Sure, Yeah it does. Yeah, follow up questions welcome. 980 00:52:46,680 --> 00:52:48,879 Speaker 1: But it's a moment where you should be skeptical, where 981 00:52:48,920 --> 00:52:51,479 Speaker 1: you should ask, hmm, how do we know that's really true? 982 00:52:51,520 --> 00:52:53,319 Speaker 1: I hear this all the time. People are telling me 983 00:52:53,360 --> 00:52:57,480 Speaker 1: quantum mechanics is random? What experiment really proves it? And 984 00:52:57,600 --> 00:52:59,480 Speaker 1: you should demand an answer, and you should demand that 985 00:52:59,560 --> 00:53:03,799 Speaker 1: intuitive explanation that satisfies you, because this is something that's 986 00:53:03,800 --> 00:53:06,719 Speaker 1: true about the whole universe, and the philosophical implications are 987 00:53:06,960 --> 00:53:10,600 Speaker 1: huge and far reaching. And so before you like update 988 00:53:10,640 --> 00:53:13,000 Speaker 1: your priors and change the way you look at the universe, like, 989 00:53:13,120 --> 00:53:14,319 Speaker 1: make sure it makes sense to you. 990 00:53:14,600 --> 00:53:19,520 Speaker 2: I think my new favorite conspiracy theory is superdeterminism. 991 00:53:20,800 --> 00:53:23,280 Speaker 1: Because it includes all the other conspiracy theory. 992 00:53:23,360 --> 00:53:26,839 Speaker 2: It's right, that's right, all right. 993 00:53:26,880 --> 00:53:29,120 Speaker 1: Well, thanks very much everyone who wrote in asking for 994 00:53:29,160 --> 00:53:31,800 Speaker 1: an explanation of quanam entanglement. I hope that helped. 995 00:53:32,000 --> 00:53:41,280 Speaker 2: It Sure helped me. Have a good day everyone. Daniel 996 00:53:41,280 --> 00:53:45,000 Speaker 2: and Kelly's Extraordinary Universe is produced by iHeartRadio. 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