1 00:00:08,440 --> 00:00:12,320 Speaker 1: Hey, or hey, I have a really practical question for you. Well, 2 00:00:12,360 --> 00:00:14,920 Speaker 1: you know I'm an engineer, so practical is my middle name. 3 00:00:15,280 --> 00:00:18,520 Speaker 1: All right, Well, here's the question. Who would you trust 4 00:00:18,600 --> 00:00:21,480 Speaker 1: more to build a spare room off of your house? 5 00:00:21,720 --> 00:00:24,960 Speaker 1: A physicist, board engineer. I think you know the answer 6 00:00:25,000 --> 00:00:28,319 Speaker 1: to that, Daniel, Not to physicists. All right, but tell 7 00:00:28,360 --> 00:00:31,080 Speaker 1: me why. You know. Physicists are awesome, but I wouldn't 8 00:00:31,120 --> 00:00:34,159 Speaker 1: say they're very precise. You know, they approximate everything. You know, 9 00:00:34,120 --> 00:00:38,040 Speaker 1: everything's like plus or minus a galactic idea. So you 10 00:00:38,080 --> 00:00:39,839 Speaker 1: want to know how big this bedroom is going to 11 00:00:39,920 --> 00:00:42,559 Speaker 1: be in advance, for example. I just don't want like 12 00:00:42,560 --> 00:00:45,160 Speaker 1: a spherical room or like a quantum on certain room. 13 00:00:45,280 --> 00:00:47,120 Speaker 1: You know, I want to know where I'm sluting. Well, 14 00:00:47,200 --> 00:00:49,720 Speaker 1: you might appreciate a surprise, but I think that's fair, 15 00:00:49,760 --> 00:00:53,520 Speaker 1: that's reasonable. But you know that sometimes physicists can actually 16 00:00:53,560 --> 00:00:57,160 Speaker 1: get really hardcore about the detail. You're still not building 17 00:00:57,160 --> 00:01:15,000 Speaker 1: my spare room. I am more hammy cartoonists and the 18 00:01:15,040 --> 00:01:18,320 Speaker 1: creator of PhD comics. Hi, I'm Daniel. I'm a particle 19 00:01:18,319 --> 00:01:21,440 Speaker 1: of physicist and you definitely don't want me building your 20 00:01:21,480 --> 00:01:23,560 Speaker 1: spare room. Is that because of you or because you're 21 00:01:23,560 --> 00:01:26,399 Speaker 1: a physicist, or is it all packaged together. You know, 22 00:01:26,440 --> 00:01:29,240 Speaker 1: there's a whole spectrum of physicists. There's the kind that 23 00:01:29,319 --> 00:01:32,280 Speaker 1: really likes to build stuff, crawl around on the detector 24 00:01:32,360 --> 00:01:34,560 Speaker 1: with a hammer and a wrench and and get dirty. 25 00:01:34,560 --> 00:01:35,840 Speaker 1: And then there's the kind of like to sit in 26 00:01:35,920 --> 00:01:39,040 Speaker 1: front of a laptop and analyze data and think about statistics. 27 00:01:39,280 --> 00:01:42,640 Speaker 1: And I'm definitely more of that second kind. Well, you 28 00:01:42,680 --> 00:01:45,000 Speaker 1: can check out my house in your laptop and think 29 00:01:45,000 --> 00:01:47,080 Speaker 1: about it for a long time. I'll build you a 30 00:01:47,200 --> 00:01:51,240 Speaker 1: virtual spare room. There you go. I'll program another spare 31 00:01:51,320 --> 00:01:54,480 Speaker 1: room in the simulation of your universe. It sometimes exists 32 00:01:54,480 --> 00:01:58,640 Speaker 1: in this universe and sometimes it doesn't. It's theoretical. That's right. 33 00:01:58,800 --> 00:02:01,360 Speaker 1: Just step through this black hole into your new spare 34 00:02:01,440 --> 00:02:03,800 Speaker 1: rooms and cozy but welcome to our podcast Daniel and 35 00:02:03,840 --> 00:02:06,640 Speaker 1: Jorge Explain the Universe, a production of our Heart Radio 36 00:02:06,720 --> 00:02:09,000 Speaker 1: in which we talk about all the amazing things that 37 00:02:09,000 --> 00:02:11,360 Speaker 1: are happening in this universe, all the things we'd like 38 00:02:11,480 --> 00:02:14,400 Speaker 1: to understand from the very very large, very very dense, 39 00:02:14,480 --> 00:02:16,600 Speaker 1: all the way down to the very very small and 40 00:02:16,639 --> 00:02:19,800 Speaker 1: the very very weird. Yeah, because the universe has a 41 00:02:19,840 --> 00:02:22,800 Speaker 1: lot of amazing things and all kinds of skills, you know, 42 00:02:22,919 --> 00:02:27,799 Speaker 1: galactic cosmological skills, But there are also amazing things happening 43 00:02:27,960 --> 00:02:31,960 Speaker 1: at the smallest scales of reality and nature. That's right, 44 00:02:31,960 --> 00:02:35,359 Speaker 1: and these really tiny things they give us an amazing opportunity. 45 00:02:35,440 --> 00:02:38,400 Speaker 1: They let us test our understanding and not just do 46 00:02:38,480 --> 00:02:41,400 Speaker 1: we mostly get things right, They let us really push 47 00:02:41,440 --> 00:02:44,760 Speaker 1: our limit to understand exactly how these things are working. 48 00:02:44,919 --> 00:02:47,720 Speaker 1: Do our models predict what's happening or is there something 49 00:02:47,760 --> 00:02:49,840 Speaker 1: a little bit wrong? And that kind of raises a 50 00:02:49,960 --> 00:02:52,919 Speaker 1: question of how well do we know what's happening at 51 00:02:52,960 --> 00:02:57,040 Speaker 1: these really tiny scales, Like we can measure distances from 52 00:02:57,120 --> 00:02:59,440 Speaker 1: here to the moon, for example, or here to maybe 53 00:02:59,480 --> 00:03:01,800 Speaker 1: the next star, But how do you measure things that 54 00:03:01,840 --> 00:03:03,799 Speaker 1: are that small? And how do you know if you're right? 55 00:03:03,960 --> 00:03:05,880 Speaker 1: It definitely takes a certain skill. You have to come 56 00:03:05,960 --> 00:03:11,240 Speaker 1: up experimentally with really clever devices, things that isolate individual particles, 57 00:03:11,360 --> 00:03:13,560 Speaker 1: or get a bunch of particles and get them all 58 00:03:13,600 --> 00:03:16,720 Speaker 1: aligned and then separate them from any other effect. It's 59 00:03:16,760 --> 00:03:20,359 Speaker 1: a really particular skill in science to devise an experiment 60 00:03:20,639 --> 00:03:24,400 Speaker 1: that forces nature to reveal something for you that pushes 61 00:03:24,440 --> 00:03:27,399 Speaker 1: everything else away. Like we learned about the Lego experiment 62 00:03:27,440 --> 00:03:30,839 Speaker 1: that measures gravitational waves. There's a huge amount of cleverness 63 00:03:30,880 --> 00:03:33,760 Speaker 1: involved in isolating those things so you can see tiny 64 00:03:33,840 --> 00:03:37,520 Speaker 1: little wiggles in space. Well, this is sort of experimental cleverness, 65 00:03:37,560 --> 00:03:39,560 Speaker 1: and when you deal with particles, you need this sort 66 00:03:39,560 --> 00:03:41,800 Speaker 1: of the same kind of skill. You need to set 67 00:03:41,840 --> 00:03:43,840 Speaker 1: the universe up in a way that it has to 68 00:03:43,880 --> 00:03:47,280 Speaker 1: reveal to you very precisely the answer to your question. Right, 69 00:03:47,360 --> 00:03:50,920 Speaker 1: But sometimes a problem, right, Daniel, is that you measure 70 00:03:51,000 --> 00:03:54,640 Speaker 1: something and you don't get what you expect. You measure something, 71 00:03:54,960 --> 00:03:56,440 Speaker 1: you think it's going to be this big or this 72 00:03:56,520 --> 00:03:59,000 Speaker 1: long or this heavy, and then when you measure in reality, 73 00:03:59,440 --> 00:04:02,600 Speaker 1: it's different. Yeah, well that's not a problem. That's fantastic, 74 00:04:02,760 --> 00:04:07,600 Speaker 1: that's exciting. That's an opportunity, you know, Like, yeah, because 75 00:04:07,600 --> 00:04:09,720 Speaker 1: we have two branches of our work. We have the 76 00:04:09,760 --> 00:04:12,920 Speaker 1: experimental side that's going out and doing stuff and measuring 77 00:04:12,960 --> 00:04:16,360 Speaker 1: things and answering questions, you know, sort of asking the universe, 78 00:04:16,360 --> 00:04:18,520 Speaker 1: what do we conclude from that? How do we interpret 79 00:04:18,640 --> 00:04:21,080 Speaker 1: that and build a model of the universe in our heads, 80 00:04:21,360 --> 00:04:24,880 Speaker 1: and then turn around and predict future measurements and when 81 00:04:24,880 --> 00:04:28,279 Speaker 1: those predictions disagree with the things we observe. That gives 82 00:04:28,320 --> 00:04:30,960 Speaker 1: us an opportunity to update that model, to say, oh, 83 00:04:31,080 --> 00:04:33,680 Speaker 1: something was wrong. There's a new particle, or this particle 84 00:04:33,720 --> 00:04:36,800 Speaker 1: works differently, or black holes are actually bigger than we thought. 85 00:04:37,040 --> 00:04:39,480 Speaker 1: Those are the moments when we learn. So when theory 86 00:04:39,480 --> 00:04:43,400 Speaker 1: and experiment disagree, I smell opportunity. But how do you 87 00:04:43,440 --> 00:04:47,360 Speaker 1: know who's right. You never do, And usually they're both wrong, 88 00:04:47,720 --> 00:04:50,520 Speaker 1: and they're both wrong in different ways because there are 89 00:04:50,680 --> 00:04:54,520 Speaker 1: very very different challenges, you know, split the difference. Calculating 90 00:04:54,560 --> 00:04:58,440 Speaker 1: something theoretically has challenges of computing time and getting minus 91 00:04:58,440 --> 00:05:01,120 Speaker 1: signs right and sort of organized in your mind, and 92 00:05:01,120 --> 00:05:04,320 Speaker 1: and getting answers experimentally has all sorts of different challenges, 93 00:05:04,360 --> 00:05:07,920 Speaker 1: making things clean, making them distinct, getting a big sample 94 00:05:07,960 --> 00:05:10,960 Speaker 1: of something, getting enough material, you know, we're sometimes just 95 00:05:11,040 --> 00:05:13,680 Speaker 1: getting enough money to build the device that you need. 96 00:05:14,120 --> 00:05:16,479 Speaker 1: That's the hard part. But there is one of these 97 00:05:16,480 --> 00:05:19,760 Speaker 1: big mysteries in nature that it has to do with 98 00:05:19,839 --> 00:05:23,360 Speaker 1: a weird kind of discrepancy between what the theory predicts 99 00:05:23,440 --> 00:05:27,279 Speaker 1: and what we actually measure. So today on the podcast, 100 00:05:27,400 --> 00:05:36,520 Speaker 1: we'll be talking about mystery of the muance magnetic moment. 101 00:05:37,600 --> 00:05:41,240 Speaker 1: That sounds marvelous and magnificent. It is one of the 102 00:05:41,279 --> 00:05:45,320 Speaker 1: most amazing and marvelous moments in magnetic field history. You know, 103 00:05:45,360 --> 00:05:48,600 Speaker 1: it's an opportunity for physics to learn something because it's 104 00:05:48,640 --> 00:05:52,720 Speaker 1: something that we know how to calculate very very very precisely. 105 00:05:53,120 --> 00:05:55,280 Speaker 1: You know, if you want to find out what's wrong 106 00:05:55,320 --> 00:05:57,359 Speaker 1: with your theory, you need to find something that you 107 00:05:57,400 --> 00:06:01,400 Speaker 1: can predict very accurately and then measure you're very very accurately, 108 00:06:01,520 --> 00:06:03,920 Speaker 1: so you can compare the two and that tells you 109 00:06:03,920 --> 00:06:06,560 Speaker 1: if your theory is right or and or if you're 110 00:06:06,680 --> 00:06:10,360 Speaker 1: measuring device is working right and not just giving you 111 00:06:10,520 --> 00:06:12,960 Speaker 1: weird things. Yeah, and if you hope that your experiment 112 00:06:13,000 --> 00:06:15,520 Speaker 1: is correct, then you know, if you see a discrepancy, 113 00:06:15,640 --> 00:06:18,279 Speaker 1: tells you that your theory is wrong. And sometimes we 114 00:06:18,360 --> 00:06:20,359 Speaker 1: do this as a way to detect the presence of 115 00:06:20,400 --> 00:06:23,040 Speaker 1: new particles or you know, just to see if anything 116 00:06:23,120 --> 00:06:26,120 Speaker 1: is right, because some of these calculations are very very sensitive, 117 00:06:26,200 --> 00:06:28,039 Speaker 1: so it's a very good way to tell whether there's 118 00:06:28,040 --> 00:06:30,880 Speaker 1: anything missing in your ideas. You know, it's sort of 119 00:06:30,920 --> 00:06:33,360 Speaker 1: like if you walk around your house and you could 120 00:06:33,360 --> 00:06:36,919 Speaker 1: take a really precise measurement, you could see where everything was, 121 00:06:37,080 --> 00:06:39,280 Speaker 1: and you compared that to the drawings you have of 122 00:06:39,360 --> 00:06:41,760 Speaker 1: your house. Right, that would tell you, like, you know, 123 00:06:41,800 --> 00:06:45,120 Speaker 1: whether your house is well described by your idea of it, 124 00:06:45,800 --> 00:06:47,320 Speaker 1: or whether it was a mistake to hire you to 125 00:06:48,240 --> 00:06:50,440 Speaker 1: clearly actually probably not. How are you to measure it 126 00:06:50,520 --> 00:06:54,480 Speaker 1: also build it? I would say, Wow, this is perfect work. 127 00:06:54,520 --> 00:06:57,640 Speaker 1: You should pay your contract or double. I guess that's 128 00:06:57,640 --> 00:06:59,640 Speaker 1: a big question. And the question is how good or 129 00:06:59,680 --> 00:07:03,040 Speaker 1: physics isn't measuring things? And so we were wondering, we 130 00:07:03,040 --> 00:07:05,520 Speaker 1: were curious about how many people out there. So if 131 00:07:05,520 --> 00:07:08,839 Speaker 1: I've thought about how good our measurements of the universe are, 132 00:07:08,920 --> 00:07:13,680 Speaker 1: and in particular, what's the most precisely measured quantity in physics? So, 133 00:07:13,720 --> 00:07:15,720 Speaker 1: as usual Daniel went out there into the wilds of 134 00:07:15,760 --> 00:07:19,320 Speaker 1: the Internet to ask people what's the most precisely measured 135 00:07:19,400 --> 00:07:22,760 Speaker 1: quantity in physics? That's right, And if you're interested in 136 00:07:22,800 --> 00:07:27,320 Speaker 1: answering random internet questions without any preparation, please right to 137 00:07:27,360 --> 00:07:30,840 Speaker 1: me at feedback at Daniel and Jorge dot com and 138 00:07:30,880 --> 00:07:33,240 Speaker 1: I'll send you some questions to answer. So think about 139 00:07:33,280 --> 00:07:34,880 Speaker 1: it for a second. If you were asked, what's the 140 00:07:34,920 --> 00:07:39,160 Speaker 1: most precisely measured thing in physics. What would you answer? 141 00:07:39,760 --> 00:07:42,080 Speaker 1: Here's what people had to say. My best guess is 142 00:07:42,200 --> 00:07:46,800 Speaker 1: increments of time, accusing an atomic clock. I don't know. 143 00:07:47,440 --> 00:07:50,240 Speaker 1: I don't know, Sorry that I don't know. Is this 144 00:07:50,360 --> 00:07:53,600 Speaker 1: something to do with the plank Clint? Maybe aliens? I'm 145 00:07:53,640 --> 00:07:56,000 Speaker 1: not sure what you mean about quantity, whether that be 146 00:07:57,000 --> 00:08:00,920 Speaker 1: amount of things, how many bananas it takes to create 147 00:08:00,960 --> 00:08:05,320 Speaker 1: a black hole. I'm going to guess it's mass. Maybe 148 00:08:05,720 --> 00:08:08,560 Speaker 1: I like this question. Well, I think first we have 149 00:08:08,640 --> 00:08:13,440 Speaker 1: to define what do we mean by precisely? Maybe temperature 150 00:08:13,720 --> 00:08:16,360 Speaker 1: mass would be the most precisely measured quantity in physics 151 00:08:16,960 --> 00:08:19,800 Speaker 1: because it holds a tangible value. I reckon they can 152 00:08:19,880 --> 00:08:23,560 Speaker 1: measure pretty small, like maybe an adam. All ride a 153 00:08:23,600 --> 00:08:27,240 Speaker 1: broad range of answers, from aliens to bananas to the 154 00:08:27,280 --> 00:08:31,000 Speaker 1: plank scale. I feel like our audience is very much 155 00:08:31,000 --> 00:08:33,120 Speaker 1: in tune with what we cover here in the podcast. Yeah, 156 00:08:33,160 --> 00:08:35,600 Speaker 1: these are great answers, and I have to confess I 157 00:08:35,640 --> 00:08:38,640 Speaker 1: think that some of these answers make me rethink how 158 00:08:38,679 --> 00:08:42,080 Speaker 1: I should have asked this question, because I asked, what's 159 00:08:42,080 --> 00:08:45,880 Speaker 1: the most precisely measured quantity in physics? Like you go out, 160 00:08:46,000 --> 00:08:48,880 Speaker 1: you do an experiment, you measure something. But I think 161 00:08:49,200 --> 00:08:51,080 Speaker 1: really the question we should have asked is what's the 162 00:08:51,080 --> 00:08:54,840 Speaker 1: most precisely calculated quantity in physics? And there's a difference. 163 00:08:54,960 --> 00:08:58,120 Speaker 1: For example, the atomic clock answer is a really good one. 164 00:08:58,520 --> 00:09:00,960 Speaker 1: You know, atomic clocks are precise us too, like one 165 00:09:01,080 --> 00:09:03,680 Speaker 1: part and tend to the sixteen. You know, it takes 166 00:09:03,720 --> 00:09:06,760 Speaker 1: like ten to the sixteen seconds before they're off by 167 00:09:06,800 --> 00:09:08,839 Speaker 1: one second. So you would agree with a lot of 168 00:09:08,920 --> 00:09:12,480 Speaker 1: these alien, Yeah, some of these are really very accurate. 169 00:09:12,480 --> 00:09:15,960 Speaker 1: And for example, Lego, like we mentioned before, gravitational waves. 170 00:09:16,200 --> 00:09:18,960 Speaker 1: To detect gravitational waves, they have to measure, you know, 171 00:09:19,000 --> 00:09:21,240 Speaker 1: the change in length of something by one part in 172 00:09:21,320 --> 00:09:23,760 Speaker 1: tend to the twenty or tend to the twenty one, 173 00:09:24,240 --> 00:09:28,280 Speaker 1: which is really incredibly precise experimentally. But what I was 174 00:09:28,320 --> 00:09:30,640 Speaker 1: going for was a question of, like, what's the most 175 00:09:30,640 --> 00:09:34,080 Speaker 1: precise test we have of our theories, which requires not 176 00:09:34,200 --> 00:09:38,840 Speaker 1: just a really precise experiment, but also a really precise prediction. Oh, 177 00:09:38,880 --> 00:09:42,440 Speaker 1: I see, like what's the most precise that physicists have 178 00:09:42,559 --> 00:09:44,960 Speaker 1: been right about stuff? Is that kind of what you mean? Yeah, 179 00:09:44,960 --> 00:09:47,920 Speaker 1: because for gravitational waves, for example, that's a very precise 180 00:09:47,920 --> 00:09:50,960 Speaker 1: experimental measurement but we didn't know in advance how big 181 00:09:51,000 --> 00:09:53,920 Speaker 1: it would be, and we don't know necessarily how big 182 00:09:53,920 --> 00:09:55,599 Speaker 1: those should be. It depends on the size of the 183 00:09:55,640 --> 00:09:58,880 Speaker 1: black holes that are the same with the tomic clocks. 184 00:09:58,920 --> 00:10:01,080 Speaker 1: We can't calculate the those things as well as we 185 00:10:01,120 --> 00:10:04,160 Speaker 1: can measure them. In order to get some insight into 186 00:10:04,160 --> 00:10:06,440 Speaker 1: the universe, you need something where you can calculate it 187 00:10:06,440 --> 00:10:09,840 Speaker 1: really well and you can predict it really precisely. Interesting, 188 00:10:09,960 --> 00:10:12,360 Speaker 1: so you're kind of talking about like, according to the 189 00:10:12,400 --> 00:10:15,440 Speaker 1: laws of physics, we think that dis quantity should be this, 190 00:10:15,920 --> 00:10:18,520 Speaker 1: and then how well does it match with what we 191 00:10:18,600 --> 00:10:22,480 Speaker 1: actually measure of it exactly? Because it's those discrepancies we 192 00:10:22,520 --> 00:10:24,960 Speaker 1: need to learn something. It doesn't matter if you measure 193 00:10:24,960 --> 00:10:28,000 Speaker 1: the length of your house to one picometer, because we 194 00:10:28,040 --> 00:10:29,680 Speaker 1: don't know how big your house should be and doesn't 195 00:10:29,679 --> 00:10:32,520 Speaker 1: really tell us anything about the universe. But if you 196 00:10:32,600 --> 00:10:35,560 Speaker 1: measure something really precisely that we can also predict that 197 00:10:35,559 --> 00:10:37,880 Speaker 1: we can calculate that has to be a certain value 198 00:10:37,920 --> 00:10:40,840 Speaker 1: because of our understanding of physics. Then measuring it and 199 00:10:40,880 --> 00:10:43,400 Speaker 1: finding out it's something else gives you a clue that 200 00:10:43,520 --> 00:10:47,079 Speaker 1: something is wrong about our model. Right, Well, it seems 201 00:10:47,120 --> 00:10:50,440 Speaker 1: like there's one such thing that we're trying to predict 202 00:10:50,559 --> 00:10:52,800 Speaker 1: and measure at the same time, and that there's a 203 00:10:52,800 --> 00:10:56,040 Speaker 1: big mystery about why those two things don't match. And 204 00:10:56,080 --> 00:11:01,000 Speaker 1: that's the magnetic moment of muance, which is a great 205 00:11:01,040 --> 00:11:05,800 Speaker 1: alliteration there. I'm so pleased to have some positive feedback 206 00:11:05,840 --> 00:11:09,240 Speaker 1: for a name in particle physics from you. That's a high, 207 00:11:09,440 --> 00:11:12,880 Speaker 1: high standard for your poetic writing. Here, the mystery of 208 00:11:12,960 --> 00:11:16,320 Speaker 1: the muon magnetic moment. Yes, it's really marvelous, all right. 209 00:11:16,320 --> 00:11:18,920 Speaker 1: So this is a quantity that we have predicted using 210 00:11:19,000 --> 00:11:21,840 Speaker 1: theory and that we've measured using big machines. But those 211 00:11:21,840 --> 00:11:24,440 Speaker 1: two things don't match. That's right, all right, So let's 212 00:11:24,440 --> 00:11:26,320 Speaker 1: get into it, Daniel. Let's start with the first m 213 00:11:26,360 --> 00:11:30,040 Speaker 1: What is the magnetic moment. So when you think about particles, 214 00:11:30,080 --> 00:11:32,880 Speaker 1: remember we like to think of them as little dots 215 00:11:32,880 --> 00:11:35,800 Speaker 1: in space that have labels, and those labels can be 216 00:11:35,840 --> 00:11:38,200 Speaker 1: like what's the spin or what's the charge or how 217 00:11:38,280 --> 00:11:40,760 Speaker 1: much mass do they have. We don't think of particles 218 00:11:40,840 --> 00:11:43,360 Speaker 1: is like little physical balls that actually do these things. 219 00:11:43,400 --> 00:11:46,920 Speaker 1: They're weird quantum objects and they have these labels. And 220 00:11:47,000 --> 00:11:49,320 Speaker 1: so this is one of the labels of a particle. 221 00:11:49,520 --> 00:11:52,280 Speaker 1: But it's a little weird because it's not like a 222 00:11:52,360 --> 00:11:54,640 Speaker 1: direct label. It's not like something you can put right 223 00:11:54,760 --> 00:11:59,400 Speaker 1: on the particle. Because particles they don't have a magnetic charge. 224 00:11:59,600 --> 00:12:03,640 Speaker 1: They have electric charge. That's how they feel electric fields. 225 00:12:03,679 --> 00:12:05,640 Speaker 1: But as we talked about on the podcast before, there 226 00:12:05,640 --> 00:12:08,320 Speaker 1: are no particles that just have like a north or 227 00:12:08,360 --> 00:12:11,400 Speaker 1: a south magnetic charge on their own. See, they have 228 00:12:11,440 --> 00:12:13,600 Speaker 1: an electric charge, but they don't have like a pole 229 00:12:13,679 --> 00:12:15,680 Speaker 1: like you say, like a magnet, like a north and south. 230 00:12:15,720 --> 00:12:17,360 Speaker 1: That's right, they don't have just a north and just 231 00:12:17,440 --> 00:12:20,920 Speaker 1: a south. What they have is this weird magnetic field. 232 00:12:20,920 --> 00:12:22,959 Speaker 1: It's a dipole to have a north and a south, 233 00:12:23,080 --> 00:12:25,920 Speaker 1: just like every magnet we've ever discovered has a north 234 00:12:26,000 --> 00:12:28,320 Speaker 1: and a south. And that comes from the combination of 235 00:12:28,360 --> 00:12:32,280 Speaker 1: having charge and having spin because charge and spin together 236 00:12:32,640 --> 00:12:36,760 Speaker 1: gives you some sort of magnetic interaction. Okay, so particles 237 00:12:36,880 --> 00:12:39,800 Speaker 1: have spin and charge and together they have a like 238 00:12:39,880 --> 00:12:42,640 Speaker 1: a pole, like a magnet, little magnet inside of it. Yeah, 239 00:12:42,640 --> 00:12:44,920 Speaker 1: and that's what we call the magnetic moment. It's the 240 00:12:45,040 --> 00:12:48,160 Speaker 1: part of the muan that is affected by a magnetic field. 241 00:12:48,600 --> 00:12:51,320 Speaker 1: And you know, fundamentally it comes from having charge and 242 00:12:51,360 --> 00:12:54,160 Speaker 1: from spinning. And that's because it has a magnetic moment. 243 00:12:54,200 --> 00:12:55,920 Speaker 1: It doesn't have a magnetic charge. It's not a north 244 00:12:56,000 --> 00:12:58,840 Speaker 1: or a south, but it is affected by the magnetic field. 245 00:12:59,160 --> 00:13:01,160 Speaker 1: And that's what we mean when we say the magnetic 246 00:13:01,280 --> 00:13:03,800 Speaker 1: moment of the muan. How a muan is affected by 247 00:13:03,840 --> 00:13:06,120 Speaker 1: a magnet. It's not the moment for like an electron 248 00:13:06,200 --> 00:13:10,400 Speaker 1: looks at a positron and they feel that attraction towards. No, 249 00:13:10,480 --> 00:13:12,760 Speaker 1: it's not. It's not a dramatic moment. It's not something 250 00:13:12,880 --> 00:13:15,400 Speaker 1: exists in like theory of screenplays or anything like that, 251 00:13:16,480 --> 00:13:18,920 Speaker 1: unless you're writing a movie about particles, in which case 252 00:13:18,920 --> 00:13:22,120 Speaker 1: there probably is an electrifying moment for the muan. Wow, 253 00:13:22,480 --> 00:13:26,640 Speaker 1: you would totally watch that movie. Um, I totally have 254 00:13:26,760 --> 00:13:29,520 Speaker 1: that movie script already in a drawer in my house. 255 00:13:30,520 --> 00:13:33,559 Speaker 1: It's been sent to several Hollywood agents, but nobody seems 256 00:13:33,600 --> 00:13:37,959 Speaker 1: to be writing. Consider this podcast my pitch for this project. 257 00:13:38,400 --> 00:13:40,120 Speaker 1: I would definitely watch that movie, but I have not 258 00:13:40,240 --> 00:13:43,240 Speaker 1: yet written the script anyway. So we're interested in you know, 259 00:13:43,320 --> 00:13:45,839 Speaker 1: what happens when you put a magnetic field on a muan. 260 00:13:46,280 --> 00:13:48,040 Speaker 1: And this is something we can measure because we can 261 00:13:48,080 --> 00:13:51,160 Speaker 1: do that experiment, and it's also something we can calculate, 262 00:13:51,240 --> 00:13:54,600 Speaker 1: and it turns out to be really sensitive to exactly 263 00:13:54,600 --> 00:13:59,000 Speaker 1: what's happening into some other big questions about how particles 264 00:13:59,040 --> 00:14:01,520 Speaker 1: work well, And maybe let's go back a step and 265 00:14:01,559 --> 00:14:03,920 Speaker 1: cover the other m which is the muon. So muan 266 00:14:04,240 --> 00:14:06,800 Speaker 1: is like an electron, Is it like a quirk? Yeah, 267 00:14:06,840 --> 00:14:10,400 Speaker 1: So we are made out of quirks and electrons. Right, 268 00:14:10,520 --> 00:14:12,840 Speaker 1: We have quirks that make up the protons and neutrons 269 00:14:12,840 --> 00:14:15,480 Speaker 1: inside our atom, and then we have electrons whizzing around them. 270 00:14:15,520 --> 00:14:17,880 Speaker 1: But each of those particles have other copies. There are 271 00:14:17,880 --> 00:14:20,360 Speaker 1: other kinds of quirks, and there are also other kinds 272 00:14:20,360 --> 00:14:23,840 Speaker 1: of electrons. So there's a heavier version of the electron. 273 00:14:23,880 --> 00:14:27,240 Speaker 1: We call that a muan, exactly the same as the electron, 274 00:14:27,280 --> 00:14:30,600 Speaker 1: except has a lot more mass. And there's another one 275 00:14:30,640 --> 00:14:34,080 Speaker 1: even called the towel. So the electron has these two cousins, 276 00:14:34,280 --> 00:14:36,640 Speaker 1: the muon and the towel that have all the same 277 00:14:36,680 --> 00:14:39,520 Speaker 1: interactions and all the same properties, like the same charge, 278 00:14:39,800 --> 00:14:43,840 Speaker 1: the same spin, but just heavier match, just heavier mass. Yeah, 279 00:14:44,000 --> 00:14:46,200 Speaker 1: and it's weird. We don't know why they exist, Like 280 00:14:46,240 --> 00:14:47,920 Speaker 1: why do we have the muan. Why do we have 281 00:14:48,000 --> 00:14:50,320 Speaker 1: the tow Why does the electron have two cousins and 282 00:14:50,400 --> 00:14:53,520 Speaker 1: not nine cousins or seventeen cousins or any cousins like 283 00:14:53,560 --> 00:14:58,160 Speaker 1: my cousin? Are they good for anything? I'm not going 284 00:14:58,240 --> 00:15:00,520 Speaker 1: to get in the middle of that family dispute. We 285 00:15:00,680 --> 00:15:04,120 Speaker 1: have cousins, so we want specified which one I'm talking about. 286 00:15:04,600 --> 00:15:06,080 Speaker 1: But what I guess what I mean is like, is 287 00:15:06,080 --> 00:15:08,640 Speaker 1: it good for anything? Like does it form part of 288 00:15:09,240 --> 00:15:10,680 Speaker 1: you know, can you make an atom out of them? 289 00:15:10,760 --> 00:15:13,000 Speaker 1: Or do we just know them kind of theoretically, or 290 00:15:13,240 --> 00:15:15,720 Speaker 1: we know that they formed, but then they disappear quickly. 291 00:15:15,920 --> 00:15:18,720 Speaker 1: That's right. They're not stable, so you can form atoms 292 00:15:18,720 --> 00:15:21,040 Speaker 1: out of them. You can take a proton and put 293 00:15:21,040 --> 00:15:23,480 Speaker 1: a mu on around it and form a bound state. 294 00:15:23,920 --> 00:15:26,760 Speaker 1: But the muan lasts for you know, a few microseconds. 295 00:15:27,080 --> 00:15:30,720 Speaker 1: Remember that heavy particles don't survive very long in the universe. Actually, 296 00:15:31,000 --> 00:15:32,960 Speaker 1: in its reference frame, if you were riding on the 297 00:15:33,000 --> 00:15:35,080 Speaker 1: back of a muan, you'd see that it lasts a 298 00:15:35,080 --> 00:15:38,720 Speaker 1: few microseconds. But because they move so fast, their clocks 299 00:15:38,720 --> 00:15:41,720 Speaker 1: are slowed down. So as we watch the muan, we 300 00:15:41,760 --> 00:15:45,640 Speaker 1: see them live their three microsecond lifetime. Over a longer 301 00:15:45,680 --> 00:15:49,160 Speaker 1: period because of time dilation, so they don't last terribly long. 302 00:15:49,200 --> 00:15:51,880 Speaker 1: It's still you know, seconds or minutes. But muans don't 303 00:15:51,920 --> 00:15:54,680 Speaker 1: last in our universe because they're heavy. They effectively turn 304 00:15:54,760 --> 00:15:58,119 Speaker 1: into electrons. All right, So there's a big mystery regarding 305 00:15:58,240 --> 00:16:01,200 Speaker 1: the magnetic moment of the eu on. So let's get 306 00:16:01,200 --> 00:16:03,760 Speaker 1: into the theory and the experiment and talk about what 307 00:16:03,800 --> 00:16:19,000 Speaker 1: it means. But first let's take a quick break a right, Daniel, 308 00:16:19,040 --> 00:16:22,920 Speaker 1: we're talking about the magnificent mystery of the marvelous muon 309 00:16:23,080 --> 00:16:31,080 Speaker 1: magnetic moment. Momentarily, hi rolls in your mouth. It's delicious. Um, 310 00:16:31,120 --> 00:16:33,880 Speaker 1: So yeah, so tell me about this mystery. So we 311 00:16:33,960 --> 00:16:36,480 Speaker 1: know about the muan and you're saying that we can 312 00:16:36,640 --> 00:16:40,320 Speaker 1: the theory predicts its magnetic moment. How can the theory 313 00:16:40,360 --> 00:16:42,240 Speaker 1: predict something like that, Well, we think about it in 314 00:16:42,320 --> 00:16:45,640 Speaker 1: terms of particles, right, We're talking about how the muon 315 00:16:45,760 --> 00:16:48,600 Speaker 1: is affected by a magnetic field. But a magnetic field 316 00:16:48,600 --> 00:16:51,680 Speaker 1: we know is really carried by photons. Like when things 317 00:16:51,800 --> 00:16:55,480 Speaker 1: interact electromagnetically, we can imagine that as being done by 318 00:16:55,560 --> 00:16:59,680 Speaker 1: photons moving through space carrying information. Remember, every force that 319 00:16:59,720 --> 00:17:03,400 Speaker 1: we think about electromagnetism, the strong force the weak force 320 00:17:03,560 --> 00:17:06,520 Speaker 1: has these particles to sort of do its job, and 321 00:17:06,520 --> 00:17:09,760 Speaker 1: in the case of the electromagnetic interaction, it's the photon. 322 00:17:10,200 --> 00:17:12,960 Speaker 1: So when you think about how a muon is affected 323 00:17:12,960 --> 00:17:16,520 Speaker 1: by a magnetic field, really on the sort of particle level, 324 00:17:16,560 --> 00:17:19,240 Speaker 1: what you're thinking about is what happens when a photon 325 00:17:19,400 --> 00:17:22,240 Speaker 1: hits a muon, or how does a photon interact with 326 00:17:22,280 --> 00:17:24,960 Speaker 1: a muon. That's sort of like the basic tinker toy 327 00:17:25,040 --> 00:17:28,919 Speaker 1: element of particle physics that lets muans be affected by 328 00:17:29,000 --> 00:17:34,080 Speaker 1: magnetic fields, right, because magnetic fields are transmitted by photons. Yeah, 329 00:17:34,119 --> 00:17:37,639 Speaker 1: magnetic fields are basically photons. We can think about like 330 00:17:37,680 --> 00:17:41,320 Speaker 1: our fields particles or particles fields, but they're very tightly connected. 331 00:17:42,040 --> 00:17:44,359 Speaker 1: So like if I throw a muon at a bunch 332 00:17:44,359 --> 00:17:47,720 Speaker 1: of magnets and it curves one way, it's not because 333 00:17:47,760 --> 00:17:50,080 Speaker 1: it's something in it. It's because it's like hitting and 334 00:17:50,160 --> 00:17:53,520 Speaker 1: interacting with photons. Yeah, exactly, it's getting bent by the 335 00:17:53,560 --> 00:17:56,639 Speaker 1: magnetic field. And very natural way to think about that 336 00:17:56,760 --> 00:17:59,679 Speaker 1: is in terms of photons being generated by you know 337 00:17:59,720 --> 00:18:02,120 Speaker 1: whatever where the source of your magnetic field is and 338 00:18:02,160 --> 00:18:05,960 Speaker 1: pushing the muan. All right, So then we think of 339 00:18:06,080 --> 00:18:09,320 Speaker 1: its interactions is hitting photons, and so how does that 340 00:18:09,480 --> 00:18:12,640 Speaker 1: help us predict its magnetic moment. Well, it's fascinating because 341 00:18:13,080 --> 00:18:15,600 Speaker 1: there's a whole bunch of different ways that a photon 342 00:18:15,800 --> 00:18:17,960 Speaker 1: can hit that mu on. Like the simplest thing is 343 00:18:18,240 --> 00:18:21,040 Speaker 1: photon hits the muon and bounces off, right, So you 344 00:18:21,080 --> 00:18:24,800 Speaker 1: have photon muan interaction very simple, Like in your mind, 345 00:18:24,840 --> 00:18:27,200 Speaker 1: you have a couple just little lines of particles that 346 00:18:27,280 --> 00:18:30,000 Speaker 1: intersect and then they go their separate ways. That's the 347 00:18:30,040 --> 00:18:33,240 Speaker 1: simplest thing, and you can use that to calculate, all right, 348 00:18:33,480 --> 00:18:35,680 Speaker 1: what's the strength of the magnetic moment of the muan? 349 00:18:36,119 --> 00:18:38,560 Speaker 1: And if you did that calculation, you get a pretty 350 00:18:38,600 --> 00:18:41,080 Speaker 1: simple answer. This was done first by a guy named 351 00:18:41,160 --> 00:18:44,359 Speaker 1: Julian Schwinger, and he was so proud of this calculation 352 00:18:44,520 --> 00:18:47,040 Speaker 1: that he actually had this number. It's alpha and the 353 00:18:47,080 --> 00:18:50,000 Speaker 1: fine structure constant over to pie. He put this number 354 00:18:50,080 --> 00:18:54,040 Speaker 1: on his tombstone. He's like, don't forget I came up 355 00:18:54,080 --> 00:18:57,199 Speaker 1: with this. Seriously, it's like it's a beautiful calculation. He 356 00:18:57,280 --> 00:18:59,359 Speaker 1: was so proud. This guy did a huge amount of 357 00:18:59,359 --> 00:19:02,360 Speaker 1: physics in his lifetime. He's basically the person who proved 358 00:19:02,560 --> 00:19:06,320 Speaker 1: that Fynman's theory of quantum electro dynamics actually work. Finding 359 00:19:06,400 --> 00:19:08,920 Speaker 1: like sketched a bunch of doodles and had a few ideas, 360 00:19:09,080 --> 00:19:11,960 Speaker 1: but never like actually made it work. And Julian Schwinger 361 00:19:12,000 --> 00:19:14,320 Speaker 1: was like, all right, let's do all the calculations and 362 00:19:14,359 --> 00:19:16,520 Speaker 1: see if this is right. But that benefit in his 363 00:19:16,560 --> 00:19:20,320 Speaker 1: tool stone, I guess this is a really succinct way 364 00:19:20,320 --> 00:19:22,960 Speaker 1: to just sort of like sum up the guy's life. Anyway, 365 00:19:23,080 --> 00:19:25,440 Speaker 1: the point is that there are other things the photon 366 00:19:25,520 --> 00:19:28,200 Speaker 1: can do also. It doesn't just have to bounce off 367 00:19:28,200 --> 00:19:31,240 Speaker 1: the muan on its way there. It could like split 368 00:19:31,320 --> 00:19:34,480 Speaker 1: into an electron and positron and then convert back into 369 00:19:34,520 --> 00:19:38,679 Speaker 1: a photon and then go off. Or it can emit 370 00:19:38,720 --> 00:19:42,040 Speaker 1: a particle and then reabsorb that first particle. So if 371 00:19:42,040 --> 00:19:44,920 Speaker 1: you'd like drawing these Fineman diagrams these ideas for how 372 00:19:44,960 --> 00:19:46,760 Speaker 1: this happens, all you have to do is add a 373 00:19:46,760 --> 00:19:50,480 Speaker 1: couple more lines, and all these things describe totally valid 374 00:19:50,520 --> 00:19:53,800 Speaker 1: things the photon could do as it interacts with the muon, 375 00:19:54,160 --> 00:20:00,400 Speaker 1: and those change effectively the muan's magnetic moment. See, so 376 00:20:00,560 --> 00:20:03,280 Speaker 1: it's kind of like the muon doesn't really have a 377 00:20:03,359 --> 00:20:06,520 Speaker 1: magnetic moment. How does it interact with a photon? Its 378 00:20:06,520 --> 00:20:09,560 Speaker 1: interaction with the photon is essentially what determines how it 379 00:20:09,680 --> 00:20:13,600 Speaker 1: reacts to magnetic fields, which is its magnetic moment. And 380 00:20:13,640 --> 00:20:16,479 Speaker 1: photons are crazy, they're like always turning into other stuff 381 00:20:16,480 --> 00:20:19,440 Speaker 1: and spewing off particles and reabsorbing them. And the real 382 00:20:19,720 --> 00:20:22,159 Speaker 1: actual thing that happens between a mean and a photon 383 00:20:22,520 --> 00:20:25,440 Speaker 1: is some some of all those things, all those things 384 00:20:25,480 --> 00:20:28,200 Speaker 1: mixed together, which you can and that you can predict 385 00:20:28,240 --> 00:20:30,520 Speaker 1: with the theory. Like your theory, you can like write 386 00:20:30,560 --> 00:20:32,399 Speaker 1: this down in a piece of paper, like what happens 387 00:20:32,400 --> 00:20:35,240 Speaker 1: if a photon hits the muan, and you can in 388 00:20:35,320 --> 00:20:37,560 Speaker 1: a piece of paper you can work out how that 389 00:20:38,359 --> 00:20:41,760 Speaker 1: muan should bend its path or how we should get deflected. 390 00:20:42,760 --> 00:20:44,399 Speaker 1: And then you can say, well, what if it was 391 00:20:44,400 --> 00:20:46,720 Speaker 1: a little bit more complicated, what if it also emitted 392 00:20:46,760 --> 00:20:50,040 Speaker 1: another particle at the same time, Then it would change 393 00:20:50,080 --> 00:20:53,359 Speaker 1: your calculation. And you know, as you make these things 394 00:20:53,359 --> 00:20:56,040 Speaker 1: more complex, there are more and more possibilities, so it 395 00:20:56,040 --> 00:21:00,560 Speaker 1: becomes very challenging theoretically to account for all the different things. 396 00:21:00,560 --> 00:21:04,800 Speaker 1: But that's also gives you an opportunity because if there 397 00:21:04,800 --> 00:21:07,520 Speaker 1: are crazy particles out there that you would never considered, 398 00:21:07,880 --> 00:21:10,119 Speaker 1: then the photon could be turning into them, could be 399 00:21:10,160 --> 00:21:13,080 Speaker 1: like interacting with them, could be like popping into existence 400 00:21:13,320 --> 00:21:16,600 Speaker 1: some weird new particle you never imagined. And that would 401 00:21:16,680 --> 00:21:21,359 Speaker 1: change how it interacts with the muan because it would 402 00:21:21,359 --> 00:21:24,520 Speaker 1: lose some energy. It would just it would change its angle, 403 00:21:24,520 --> 00:21:27,040 Speaker 1: it would change its direction, it would change the probability 404 00:21:27,040 --> 00:21:30,520 Speaker 1: of this thing happening at all. And so in this way, 405 00:21:30,760 --> 00:21:33,000 Speaker 1: the photon interacting with the muan is sort of like 406 00:21:33,040 --> 00:21:35,960 Speaker 1: a probe of the whole universe because along the way, 407 00:21:35,960 --> 00:21:38,280 Speaker 1: the photon can do all sorts of crazy stuff. You 408 00:21:38,320 --> 00:21:41,240 Speaker 1: can do anything that quantum mechanics lets it do, and 409 00:21:41,280 --> 00:21:44,679 Speaker 1: what happened affects how it interacts with the muon. And 410 00:21:44,720 --> 00:21:47,720 Speaker 1: so by calculating this quantity and then measuring it, you 411 00:21:47,760 --> 00:21:50,640 Speaker 1: can ask, like, is there anything else that the photon 412 00:21:50,720 --> 00:21:53,400 Speaker 1: is doing along the way that's changing how it interacts 413 00:21:53,440 --> 00:21:55,000 Speaker 1: with the mu want to see, like how good are 414 00:21:55,000 --> 00:21:58,639 Speaker 1: we predicting what photons actually do. Yeah, it's like you 415 00:21:58,680 --> 00:22:01,320 Speaker 1: said to photons, hey, go crazy, do anything you want 416 00:22:01,320 --> 00:22:03,800 Speaker 1: to do, and then we're going to try to calculate 417 00:22:03,840 --> 00:22:05,800 Speaker 1: all the things we think you can do, and then 418 00:22:05,880 --> 00:22:08,840 Speaker 1: let's compare. And you know, if it turns out you're 419 00:22:08,920 --> 00:22:10,520 Speaker 1: dancing with a new kind of particle we've never heard 420 00:22:10,560 --> 00:22:14,440 Speaker 1: about before, we're gonna know you're like stalker fans. Yeah, 421 00:22:14,440 --> 00:22:16,359 Speaker 1: and you know, people like me, I like to discover 422 00:22:16,400 --> 00:22:20,120 Speaker 1: new particles by sort of making them concretely, like pouring 423 00:22:20,240 --> 00:22:23,000 Speaker 1: enough energy into a collider so that we have enough 424 00:22:23,080 --> 00:22:25,360 Speaker 1: energy to make this new particle. And see it's sort 425 00:22:25,359 --> 00:22:28,040 Speaker 1: of directly, but this is another way to do it, 426 00:22:28,080 --> 00:22:30,359 Speaker 1: is to like look for these particles just sort of 427 00:22:30,400 --> 00:22:34,040 Speaker 1: like briefly popping into existence as photons do their crazy 428 00:22:34,119 --> 00:22:37,000 Speaker 1: dance with muans. And I guess my question is why 429 00:22:37,080 --> 00:22:39,600 Speaker 1: the mean like couldn't I mean, all these questions and 430 00:22:39,600 --> 00:22:43,000 Speaker 1: all these magnetic moment ideas we should work for any 431 00:22:43,040 --> 00:22:46,280 Speaker 1: other particle, right, So why are we focusing on the 432 00:22:46,359 --> 00:22:49,159 Speaker 1: muon specifically? And you can do these calculations also for 433 00:22:49,200 --> 00:22:52,119 Speaker 1: the electron and also for the town, right, but the 434 00:22:52,200 --> 00:22:54,479 Speaker 1: muon is sort of in a sweet spot because it's 435 00:22:54,480 --> 00:22:57,040 Speaker 1: a little bit heavier, it's sort of easier to handle. 436 00:22:57,400 --> 00:22:59,960 Speaker 1: The new physics should happen to all of these particles. Right, 437 00:23:00,240 --> 00:23:03,560 Speaker 1: but it has essentially a proportionately larger effect on the 438 00:23:03,680 --> 00:23:06,879 Speaker 1: muan because it has a larger mass. I see, So 439 00:23:06,960 --> 00:23:09,480 Speaker 1: lemon is like the guinea pig. Yeah, the muan is 440 00:23:09,520 --> 00:23:11,920 Speaker 1: like the best place to get the universe to reveal 441 00:23:12,040 --> 00:23:15,440 Speaker 1: all these little details, all right, And so you can 442 00:23:15,520 --> 00:23:17,359 Speaker 1: run the math and it should tell you how the 443 00:23:17,440 --> 00:23:19,879 Speaker 1: muon should bend in a magnetic field. And you can 444 00:23:19,920 --> 00:23:22,959 Speaker 1: also measure how, like you can throw me on at 445 00:23:22,960 --> 00:23:25,399 Speaker 1: a magnetic field and see how it bends. That's the 446 00:23:25,440 --> 00:23:27,600 Speaker 1: experimental side. Yeah, But before we move on to the 447 00:23:27,600 --> 00:23:29,800 Speaker 1: experimental side, I gotta sort of shout out to the 448 00:23:29,800 --> 00:23:32,720 Speaker 1: theory here, because this is what I meant earlier about 449 00:23:32,720 --> 00:23:36,679 Speaker 1: being really precise. On the theoretical side, this quantity, the 450 00:23:36,760 --> 00:23:40,719 Speaker 1: magnetic moment of the muan, is the number that theorists 451 00:23:40,840 --> 00:23:45,560 Speaker 1: know best. It's the most precisely calculated quantity basically in 452 00:23:45,600 --> 00:23:47,760 Speaker 1: the universe as far as we know, unless there are 453 00:23:47,800 --> 00:23:51,720 Speaker 1: alien physicists doing it out there. What how can something 454 00:23:51,760 --> 00:23:55,720 Speaker 1: theoretical be precise? Doesn't precision mean like how right you are. 455 00:23:55,920 --> 00:23:57,600 Speaker 1: It doesn't mean how right you are. And when we 456 00:23:57,640 --> 00:24:00,160 Speaker 1: do these calculations, we start with the simplest idea as 457 00:24:00,160 --> 00:24:02,520 Speaker 1: we say, well, what's the simplest thing of photon can do? 458 00:24:02,680 --> 00:24:04,800 Speaker 1: And that gets you mostly right, and they think, well, 459 00:24:05,000 --> 00:24:07,000 Speaker 1: what if it does one weird thing along the way, 460 00:24:07,280 --> 00:24:09,240 Speaker 1: And there's like nineteen ways for that to happen, So 461 00:24:09,280 --> 00:24:12,120 Speaker 1: you add nineteen calculations. Well what if it did two 462 00:24:12,160 --> 00:24:14,800 Speaker 1: weird things along the way. Okay, now there's nineteen squared 463 00:24:14,880 --> 00:24:17,399 Speaker 1: ways to do that, and each of these gives us 464 00:24:17,440 --> 00:24:20,040 Speaker 1: smaller and smaller effect. And so as you add up 465 00:24:20,119 --> 00:24:22,840 Speaker 1: more and more of these ideas you're considering, you get 466 00:24:22,880 --> 00:24:26,080 Speaker 1: closer to the true answer, but also becomes harder. And 467 00:24:26,160 --> 00:24:28,199 Speaker 1: so now they're at the point where they're calculating like 468 00:24:28,480 --> 00:24:31,480 Speaker 1: millions and millions of possibilities. Maybe first to turn to 469 00:24:31,600 --> 00:24:33,560 Speaker 1: ano electron, and that electron did some weird thing, which 470 00:24:33,560 --> 00:24:35,960 Speaker 1: turn to into a photon, which then did some weird thing. 471 00:24:36,600 --> 00:24:40,600 Speaker 1: And so they've estimated sort of theoretically how precise this is, 472 00:24:40,680 --> 00:24:43,600 Speaker 1: Like it's impossible to get it exactly right because you 473 00:24:43,680 --> 00:24:46,920 Speaker 1: need to do an infinite number of calculations, so they 474 00:24:46,920 --> 00:24:49,680 Speaker 1: can estimate how close they get based on how much 475 00:24:49,720 --> 00:24:52,879 Speaker 1: is the answer changing as they add more ideas, So 476 00:24:52,920 --> 00:24:57,000 Speaker 1: they're asthm topically approaching the deep truth. I guess there's 477 00:24:57,040 --> 00:24:59,640 Speaker 1: a you know, an engineering, there's always this issue about 478 00:24:59,640 --> 00:25:04,160 Speaker 1: the different between accuracy and precision, like accuracies how right 479 00:25:04,240 --> 00:25:07,480 Speaker 1: you are, and precision is like how sure you are? 480 00:25:08,000 --> 00:25:10,000 Speaker 1: So is the thing that's happening here? Is it that 481 00:25:10,280 --> 00:25:14,879 Speaker 1: theories are pretty sure they know what the moment of 482 00:25:14,920 --> 00:25:17,439 Speaker 1: the muan is, like they think they've covered all the angles, 483 00:25:17,440 --> 00:25:20,080 Speaker 1: so they're pretty sure, but maybe they don't know if 484 00:25:20,080 --> 00:25:22,480 Speaker 1: it's the actual value. Yeah, you know, I have equivalent 485 00:25:22,520 --> 00:25:25,840 Speaker 1: with theoretical physics here because experimentalists trying to be really 486 00:25:25,880 --> 00:25:29,439 Speaker 1: formal about the statistical statements we make. If we say, okay, 487 00:25:29,440 --> 00:25:32,840 Speaker 1: there's an uncertainty here, that means something very specific. Statistically, 488 00:25:32,880 --> 00:25:36,000 Speaker 1: it means if you did the same experiment a hundred times, 489 00:25:36,280 --> 00:25:39,719 Speaker 1: you would get the answer within your uncertainty bounds sixty 490 00:25:39,920 --> 00:25:42,000 Speaker 1: percent of the time or something like that, or a 491 00:25:42,040 --> 00:25:45,080 Speaker 1: different answer if your Bayesian. That's precision. There is are 492 00:25:45,080 --> 00:25:47,240 Speaker 1: a lot more hand wavy, you know, they're like, well, 493 00:25:47,600 --> 00:25:50,040 Speaker 1: we tweaked a couple knobs and got different answers, and 494 00:25:50,080 --> 00:25:53,600 Speaker 1: so you know that's the uncertainty. We multiplied some things 495 00:25:53,600 --> 00:25:56,200 Speaker 1: by two just to see how things would change. So 496 00:25:56,480 --> 00:25:59,800 Speaker 1: that's what we're calling the uncertainty. And you know, it's harder, 497 00:25:59,800 --> 00:26:02,520 Speaker 1: it's different. They're not measuring things about the universe. They're 498 00:26:02,520 --> 00:26:04,520 Speaker 1: just trying to like guess how closely they are the 499 00:26:04,600 --> 00:26:07,600 Speaker 1: right answers. So I guess maybe the title should really 500 00:26:07,640 --> 00:26:12,600 Speaker 1: be the most precisely guessed that theory quantity ever, you 501 00:26:12,600 --> 00:26:14,320 Speaker 1: know what I mean. Like they put a lot of 502 00:26:14,359 --> 00:26:16,960 Speaker 1: attention into the They've covered every angle on so they're 503 00:26:17,080 --> 00:26:20,040 Speaker 1: they're pretty sure that this is what the plan is. Yeah, 504 00:26:20,119 --> 00:26:22,840 Speaker 1: I suppose so, although you know, there have been moments 505 00:26:22,920 --> 00:26:25,600 Speaker 1: in this history and this is a decades long project 506 00:26:25,640 --> 00:26:28,240 Speaker 1: to make the theory more precise and make the experiment 507 00:26:28,240 --> 00:26:30,199 Speaker 1: more precise. It's a bit of an arms race to 508 00:26:30,240 --> 00:26:32,520 Speaker 1: see like who's getting more and more precise. There was 509 00:26:32,560 --> 00:26:35,399 Speaker 1: a moment in the nineties when the theorists discovered that 510 00:26:35,440 --> 00:26:37,600 Speaker 1: they had gotten the sign wrong, like that a minus 511 00:26:37,600 --> 00:26:40,119 Speaker 1: sign where there should be a positive sign, and it 512 00:26:40,240 --> 00:26:43,080 Speaker 1: changed the answer kind of a lot. So they're they're 513 00:26:43,119 --> 00:26:47,160 Speaker 1: definitely mistakes in there. Oh my gosh, who made the mistake? 514 00:26:47,359 --> 00:26:49,360 Speaker 1: Are they going to put that in their tombstone as well? 515 00:26:49,720 --> 00:26:53,320 Speaker 1: One more minus sign? Know, there are different groups, and 516 00:26:53,320 --> 00:26:56,160 Speaker 1: they're cross checking each other, and so you know, that's 517 00:26:56,160 --> 00:26:58,320 Speaker 1: another way they try to estimate how correct these things. 518 00:26:58,320 --> 00:27:01,120 Speaker 1: All right, well, let's get in to now the experiment 519 00:27:01,240 --> 00:27:04,040 Speaker 1: part of it and how well these two things match up. 520 00:27:04,240 --> 00:27:09,119 Speaker 1: Who's more precise or less accurate or more marvelous. But 521 00:27:09,240 --> 00:27:23,840 Speaker 1: first let's take a quick break. All right, we're talking 522 00:27:23,880 --> 00:27:27,040 Speaker 1: about the magnetic moment of the muan as the most 523 00:27:27,160 --> 00:27:31,800 Speaker 1: precisely guest at quantity ever, and now we're going to 524 00:27:31,920 --> 00:27:35,680 Speaker 1: measure it with an experiment, and that just involves throwing 525 00:27:35,720 --> 00:27:37,560 Speaker 1: a muan at a magnetic field and seeing where it 526 00:27:37,600 --> 00:27:39,679 Speaker 1: goes or is there is there something special going on? 527 00:27:39,880 --> 00:27:41,639 Speaker 1: You know, that would work, But what you want is 528 00:27:41,640 --> 00:27:44,280 Speaker 1: a really precise measurement. You want a measurement which is 529 00:27:44,320 --> 00:27:47,280 Speaker 1: accurate to like one part in ten to the twelve 530 00:27:47,440 --> 00:27:49,879 Speaker 1: or ten to the thirteen, and so to do that 531 00:27:49,920 --> 00:27:52,720 Speaker 1: you need a really clean setup. And so what you 532 00:27:52,800 --> 00:27:55,000 Speaker 1: described would work, but it's sort of hard to measure 533 00:27:55,000 --> 00:27:57,280 Speaker 1: it's a single particle. And so what you want is 534 00:27:57,320 --> 00:28:00,359 Speaker 1: a lot of muans. You want them all basically doing 535 00:28:00,400 --> 00:28:02,399 Speaker 1: the same thing. So you can get a bunch of 536 00:28:02,400 --> 00:28:05,000 Speaker 1: measurements and divide by a big number and it sort 537 00:28:05,000 --> 00:28:07,159 Speaker 1: of averages out some of the mistakes. And so what 538 00:28:07,200 --> 00:28:09,200 Speaker 1: they do is they get a huge pile of muans, 539 00:28:09,200 --> 00:28:12,119 Speaker 1: a big blob of muans, and they point the spin 540 00:28:12,200 --> 00:28:14,639 Speaker 1: of the muan, which is the thing that determines again 541 00:28:15,080 --> 00:28:18,199 Speaker 1: where this magnetic field is going, and they get them 542 00:28:18,240 --> 00:28:20,880 Speaker 1: to spin in the direction they're moving, and they move 543 00:28:20,920 --> 00:28:22,520 Speaker 1: them in a circle. So they have this ring in 544 00:28:22,600 --> 00:28:25,480 Speaker 1: Chicago where they have a bunch of muans and they 545 00:28:25,480 --> 00:28:29,439 Speaker 1: move them in a circle. And when muans move around 546 00:28:29,480 --> 00:28:32,680 Speaker 1: in a circle in a magnetic field, their spin will precess, 547 00:28:32,760 --> 00:28:36,239 Speaker 1: it will rotate around the access of motion. Because that's 548 00:28:36,280 --> 00:28:37,800 Speaker 1: how the physics work out. Like if you try to 549 00:28:37,800 --> 00:28:39,840 Speaker 1: ban the muon, it will also sort of change in 550 00:28:39,840 --> 00:28:41,960 Speaker 1: other ways. Yeah, Like one thing that happens to a 551 00:28:41,960 --> 00:28:43,840 Speaker 1: particle and you put it through a magnetic field is 552 00:28:43,840 --> 00:28:46,479 Speaker 1: that it bends. But a particles moving in a circle 553 00:28:46,560 --> 00:28:49,000 Speaker 1: through a magnetic field will process, It will will change 554 00:28:49,000 --> 00:28:51,760 Speaker 1: the direction in which they're pointing. So that's what they 555 00:28:51,760 --> 00:28:54,400 Speaker 1: can do, is they can measure the difference between the 556 00:28:54,400 --> 00:28:56,840 Speaker 1: direction of the magnetic field that they're putting on these 557 00:28:56,880 --> 00:29:00,320 Speaker 1: particles and the direction of the spin of the ones 558 00:29:00,360 --> 00:29:03,840 Speaker 1: which affects their magnetic moment, And so they have come 559 00:29:03,920 --> 00:29:06,160 Speaker 1: up with really clever ways to measure these things and 560 00:29:06,160 --> 00:29:08,959 Speaker 1: to reduce all sorts of uncertainties. And you know, if 561 00:29:08,960 --> 00:29:12,880 Speaker 1: you're a visual person, it's really very similar in spirit 562 00:29:12,960 --> 00:29:16,080 Speaker 1: to the experiment that looks for gravitational waves. What you're 563 00:29:16,080 --> 00:29:18,880 Speaker 1: trying to do is isolate this experiment from any other effect. 564 00:29:18,920 --> 00:29:21,120 Speaker 1: You know, like, is that the microwave oven in the 565 00:29:21,160 --> 00:29:24,320 Speaker 1: break room that's changing the answer? You do we understand 566 00:29:24,320 --> 00:29:28,760 Speaker 1: all the electromagnetic fields nearby. Is the radiation from the 567 00:29:28,800 --> 00:29:31,560 Speaker 1: ground affecting our result? It's this kind of experiment you're 568 00:29:31,600 --> 00:29:36,040 Speaker 1: like really isolating any source of noise or uncertainty. All right, 569 00:29:36,120 --> 00:29:39,080 Speaker 1: So they're spinning these muans in a circle in Chicago, 570 00:29:39,440 --> 00:29:43,840 Speaker 1: and again not in Minnesota or Milwaukee or Montana. No, 571 00:29:43,960 --> 00:29:47,240 Speaker 1: it's being done at Fermulab, the accelerator complex just outside 572 00:29:47,280 --> 00:29:50,520 Speaker 1: Chicago between Batavia and Naperville, where I did my pH 573 00:29:50,640 --> 00:29:54,160 Speaker 1: d thesis hometown plug. All right. So they're spinning these 574 00:29:54,200 --> 00:29:56,200 Speaker 1: in a in a circle, and they're measuring how they're 575 00:29:56,400 --> 00:29:59,600 Speaker 1: processing or changing in the direction of their moment, and 576 00:30:00,200 --> 00:30:04,240 Speaker 1: that tells you the magnetic moment of the muan experimentally, 577 00:30:04,720 --> 00:30:06,680 Speaker 1: and now the problem is how well does it match 578 00:30:06,720 --> 00:30:09,040 Speaker 1: with what the theorists. Yeah, that's right, that's the questions. 579 00:30:09,040 --> 00:30:10,720 Speaker 1: That we have the number from the theory and the 580 00:30:10,840 --> 00:30:13,080 Speaker 1: number from the experiment, and if you write these two 581 00:30:13,120 --> 00:30:15,640 Speaker 1: numbers down on a piece of paper, they agree to 582 00:30:15,720 --> 00:30:18,720 Speaker 1: the first what is it, like eight or nine digits 583 00:30:18,800 --> 00:30:22,440 Speaker 1: before they disagree. So it's like it's really a testament 584 00:30:22,480 --> 00:30:24,520 Speaker 1: to an incredible amount of work. I mean, you call 585 00:30:24,600 --> 00:30:26,840 Speaker 1: it guessing, but like these theorists have done a huge 586 00:30:26,840 --> 00:30:29,040 Speaker 1: amount of work to really nail this down, and the 587 00:30:29,080 --> 00:30:32,800 Speaker 1: experimentalists have done a different, difficult pile of work, and 588 00:30:32,840 --> 00:30:35,280 Speaker 1: now they have these two numbers. It's incredible to me 589 00:30:35,400 --> 00:30:38,280 Speaker 1: that they agree this closely at all. All right, so 590 00:30:38,360 --> 00:30:41,560 Speaker 1: let's maybe sign out the number for the audience here. 591 00:30:41,960 --> 00:30:45,120 Speaker 1: So the experimentalists say that the magnetic moment of the 592 00:30:45,160 --> 00:30:49,040 Speaker 1: muan is two point zero zero two three three one 593 00:30:49,160 --> 00:30:54,320 Speaker 1: eight four one eight close our mind is some small quantity, 594 00:30:54,440 --> 00:30:57,560 Speaker 1: and what are the units of these These are dimensionless units. Yeah, 595 00:30:57,600 --> 00:31:00,880 Speaker 1: so okay, that was from the experimentalist. Theorists say it 596 00:31:00,880 --> 00:31:03,840 Speaker 1: should be two point zero zero two three, three, one 597 00:31:04,040 --> 00:31:08,440 Speaker 1: eight three six to not fo, that's right. So they 598 00:31:08,480 --> 00:31:11,600 Speaker 1: agree on you know, after the decimal place, they agree 599 00:31:11,640 --> 00:31:14,680 Speaker 1: to seven digits, and then they disagree. One of them 600 00:31:14,680 --> 00:31:17,040 Speaker 1: says four one, eight and the other one says three 601 00:31:17,120 --> 00:31:20,280 Speaker 1: six two, which is not a huge difference. It's like 602 00:31:21,160 --> 00:31:24,120 Speaker 1: twelve zeros and then like, yeah, it's a bunch of 603 00:31:24,200 --> 00:31:27,000 Speaker 1: zeros and fifty six. But the fascinating thing is that 604 00:31:27,240 --> 00:31:29,640 Speaker 1: both of them are pretty confident in their results. So 605 00:31:29,680 --> 00:31:33,000 Speaker 1: there's a gap between them, very tiny gap between them, 606 00:31:33,040 --> 00:31:37,320 Speaker 1: but the uncertainty is smaller than the gap. Right, the 607 00:31:37,360 --> 00:31:40,120 Speaker 1: difference between them is fifty six, and the uncertainty is 608 00:31:40,160 --> 00:31:43,520 Speaker 1: like fifteen, So the difference is like three or three 609 00:31:43,560 --> 00:31:46,720 Speaker 1: and a half times the uncertainty. It seems really it's 610 00:31:46,760 --> 00:31:49,239 Speaker 1: so weird to me that they're so confident, you know 611 00:31:49,520 --> 00:31:52,760 Speaker 1: about these numbers, Like you know, I've done experiments, and 612 00:31:52,960 --> 00:31:55,160 Speaker 1: you know, to get that kind of position is really hard, 613 00:31:55,280 --> 00:31:57,680 Speaker 1: Like if they ran this experiment next year and the 614 00:31:57,760 --> 00:32:00,720 Speaker 1: year after that, but they still get the same exact. Yeah. 615 00:32:00,760 --> 00:32:04,640 Speaker 1: These uncertainties reflect statistical limitations, so like you haven't runned 616 00:32:04,720 --> 00:32:08,440 Speaker 1: for an infinitely long time, and also systematic uncertainties like 617 00:32:08,800 --> 00:32:12,040 Speaker 1: things you think will contribute to mismeasurement or or bias 618 00:32:12,160 --> 00:32:14,360 Speaker 1: on your result, and you know these are estimates. It 619 00:32:14,360 --> 00:32:16,560 Speaker 1: could be that they're wrong. It could be just a 620 00:32:16,600 --> 00:32:19,520 Speaker 1: basic mistake somewhere. But this is what we're trying to learn. 621 00:32:19,640 --> 00:32:22,040 Speaker 1: Like we're trying to learn, like do we understand how 622 00:32:22,040 --> 00:32:24,560 Speaker 1: to do these precision measurements or do we understand how 623 00:32:24,600 --> 00:32:27,480 Speaker 1: to do these calculations, or is there a new particle 624 00:32:27,560 --> 00:32:31,040 Speaker 1: out there that we're not factoring into our calculations that's 625 00:32:31,240 --> 00:32:33,800 Speaker 1: playing with a magnetic moment of the muant finding a 626 00:32:33,840 --> 00:32:37,000 Speaker 1: little bit? Is this the hint of the discovery of 627 00:32:37,040 --> 00:32:40,080 Speaker 1: some new particles, some new supersymmetric particle which is too 628 00:32:40,080 --> 00:32:44,040 Speaker 1: heavy to make a particle colliders and only appears very 629 00:32:44,080 --> 00:32:47,280 Speaker 1: briefly and gives these little hints to the mule, like 630 00:32:47,400 --> 00:32:52,000 Speaker 1: is there something hiding in that zero point zero zero 631 00:32:52,160 --> 00:32:55,880 Speaker 1: five six difference between the experiment and the theory, or 632 00:32:56,240 --> 00:32:58,920 Speaker 1: because they're both pretty sure of their numbers, there's now 633 00:32:58,960 --> 00:33:01,000 Speaker 1: like they're both pretty sure of their numbers. Yeah, it 634 00:33:01,040 --> 00:33:04,480 Speaker 1: couldn't be like a wire missing here or a plus 635 00:33:04,520 --> 00:33:08,440 Speaker 1: sign missing over there. They certainly could be and their 636 00:33:08,480 --> 00:33:11,600 Speaker 1: independent checks, their independent experiments, and we'll talk about that 637 00:33:11,640 --> 00:33:14,200 Speaker 1: in a moment, but they're both pretty confident. And I 638 00:33:14,240 --> 00:33:16,680 Speaker 1: remember learning about this in college and I was still 639 00:33:16,760 --> 00:33:19,240 Speaker 1: learning about quantum mechanics and how it all worked. And 640 00:33:19,280 --> 00:33:21,600 Speaker 1: at the time, I thought of physics as sort of 641 00:33:21,640 --> 00:33:24,520 Speaker 1: like a description of what we see about the universe, 642 00:33:24,600 --> 00:33:27,320 Speaker 1: just like sort of a human internal to our minds 643 00:33:27,720 --> 00:33:31,080 Speaker 1: approximation of what's happening in the universe. And I read 644 00:33:31,080 --> 00:33:33,719 Speaker 1: about this calculation, like, wow, it agrees to you know, 645 00:33:33,840 --> 00:33:36,960 Speaker 1: nine or ten decimal places. That's amazing. And I at 646 00:33:37,000 --> 00:33:40,040 Speaker 1: this moment where I thought, wait a second, maybe physics 647 00:33:40,080 --> 00:33:44,320 Speaker 1: isn't just describing approximately what's happening. Maybe we've discovered like 648 00:33:44,440 --> 00:33:47,200 Speaker 1: the source code, Like maybe this is what the universe 649 00:33:47,280 --> 00:33:50,640 Speaker 1: itself is doing. Because to get that accurate, to get 650 00:33:50,680 --> 00:33:54,160 Speaker 1: that precise, it's sort of shocking, you know, to imagine 651 00:33:54,200 --> 00:33:57,040 Speaker 1: there could be another theory that could also be that precise. 652 00:33:57,160 --> 00:33:59,920 Speaker 1: So I see, it's like, what if we actually uncover 653 00:34:00,080 --> 00:34:02,440 Speaker 1: at the code of the simulation of the universe, because 654 00:34:02,440 --> 00:34:06,320 Speaker 1: it's so we're so right, and we're so right. Yeah, 655 00:34:06,440 --> 00:34:09,240 Speaker 1: maybe the universe does run on a computer using these equations? 656 00:34:09,440 --> 00:34:11,759 Speaker 1: Is that kind of what you mean? Sort of you know, 657 00:34:12,000 --> 00:34:14,680 Speaker 1: but in a more universal way, like maybe the universe 658 00:34:14,760 --> 00:34:17,680 Speaker 1: does follow laws and it does calculations, and it follows 659 00:34:17,719 --> 00:34:20,160 Speaker 1: these rules when it does those calculations, you don't have 660 00:34:20,239 --> 00:34:23,480 Speaker 1: to be embedded in some meta universe and simulated on 661 00:34:23,520 --> 00:34:27,480 Speaker 1: a computer. Maybe the universe is doing calculations though. Anyway, 662 00:34:27,560 --> 00:34:30,920 Speaker 1: it's an incredible testament in my mind to the work 663 00:34:30,960 --> 00:34:33,400 Speaker 1: involved here, and it's amazing that it works at all. 664 00:34:33,440 --> 00:34:35,439 Speaker 1: I agree, right, But there is sort of an interesting mystery, 665 00:34:35,480 --> 00:34:37,640 Speaker 1: And I guess the weird thing is that you're telling 666 00:34:37,640 --> 00:34:41,200 Speaker 1: me that for the electron there's no difference between the 667 00:34:41,239 --> 00:34:44,120 Speaker 1: experiment and the theory. That's right, Like this difference only 668 00:34:44,120 --> 00:34:45,680 Speaker 1: shows up in the melee. We can do the same 669 00:34:45,680 --> 00:34:48,560 Speaker 1: measurement for the electron. We actually a similar number, but 670 00:34:48,640 --> 00:34:51,239 Speaker 1: there's no discrepancy. Like the electron. When they do the 671 00:34:51,239 --> 00:34:54,759 Speaker 1: theoretical calculation and they do the experimental measurement, they get 672 00:34:54,800 --> 00:34:58,200 Speaker 1: those two things to agree to within uncertainty. Now we 673 00:34:58,320 --> 00:35:01,719 Speaker 1: expect that new is it, new particles whatever, would have 674 00:35:01,760 --> 00:35:04,520 Speaker 1: a bigger effect on the muan, so it's not a 675 00:35:04,520 --> 00:35:07,520 Speaker 1: surprise that it doesn't appear there for the electrons. And 676 00:35:07,600 --> 00:35:12,799 Speaker 1: that's quite fascinating. So maybe there's something going on with 677 00:35:12,880 --> 00:35:15,680 Speaker 1: the muan that you wouldn't see in the electron. So 678 00:35:15,719 --> 00:35:17,760 Speaker 1: the electron you check that box or like the theory, 679 00:35:17,840 --> 00:35:20,480 Speaker 1: and both groups have gone at the electron with the 680 00:35:20,520 --> 00:35:23,560 Speaker 1: same kind of intensity and precision, and you can do 681 00:35:23,600 --> 00:35:26,560 Speaker 1: all the same kinds of theoretical calculations for the electron 682 00:35:26,800 --> 00:35:28,759 Speaker 1: and get a really precise number. And then you can 683 00:35:28,800 --> 00:35:32,400 Speaker 1: go measure the magnetic moment of the electron, because electrons 684 00:35:32,480 --> 00:35:35,400 Speaker 1: also bend in magnetic fields, and you can make that 685 00:35:35,440 --> 00:35:39,000 Speaker 1: measurement really, really precise, and those two numbers agree. Electrons, 686 00:35:39,239 --> 00:35:42,160 Speaker 1: we understand them like. There are no mysteries hiding under 687 00:35:42,200 --> 00:35:44,759 Speaker 1: the rug for the magnetic moment of the electron, but 688 00:35:44,960 --> 00:35:47,840 Speaker 1: for the muan, which is exactly where we would expect 689 00:35:47,920 --> 00:35:51,200 Speaker 1: to see something weird. First we start to see something weird, 690 00:35:51,239 --> 00:35:53,719 Speaker 1: all right, But it's different for the muan, which means 691 00:35:53,719 --> 00:35:55,719 Speaker 1: that it might be hiding a secret. So what does 692 00:35:55,719 --> 00:35:59,280 Speaker 1: that mean, Daniel, What could be hiding underneath the marvelousness 693 00:35:59,280 --> 00:36:01,759 Speaker 1: of the muant? Well, you know, we suspect that there 694 00:36:01,800 --> 00:36:04,719 Speaker 1: are other particles out there that we have not yet discovered. 695 00:36:05,160 --> 00:36:09,040 Speaker 1: We found six particles that are corks, six particles that 696 00:36:09,080 --> 00:36:11,520 Speaker 1: are leftons, and then a few of the particles that 697 00:36:11,640 --> 00:36:14,279 Speaker 1: mediate the interactions between them, and so we have this 698 00:36:14,440 --> 00:36:16,840 Speaker 1: pile of particles, but we don't know if those the 699 00:36:16,880 --> 00:36:19,560 Speaker 1: only particles out there. And actually it would make a 700 00:36:19,640 --> 00:36:22,279 Speaker 1: lot more sense if there were more particles, because there 701 00:36:22,280 --> 00:36:25,680 Speaker 1: are these weird patterns we found that are unexplained, and 702 00:36:25,960 --> 00:36:28,879 Speaker 1: some of them would click together really nicely if there 703 00:36:28,880 --> 00:36:31,959 Speaker 1: were new particles. Like some of the particles we've seen 704 00:36:32,040 --> 00:36:34,520 Speaker 1: are called fermions. They have spin one half, and the 705 00:36:34,560 --> 00:36:37,320 Speaker 1: other ones are called bosons because they have spin one. 706 00:36:37,440 --> 00:36:41,520 Speaker 1: There's one idea that maybe every fermion has a boson version, 707 00:36:41,840 --> 00:36:44,719 Speaker 1: like the muan has another version of it called the 708 00:36:44,800 --> 00:36:47,600 Speaker 1: smeu on, and the photon is another version of it 709 00:36:47,640 --> 00:36:51,840 Speaker 1: called the photino. And these are like just one idea 710 00:36:51,880 --> 00:36:54,160 Speaker 1: of how there could be new particles out there that 711 00:36:54,239 --> 00:36:57,880 Speaker 1: sort of solve deep problems in theoretical physics, but we 712 00:36:57,920 --> 00:37:01,040 Speaker 1: haven't seen them yet, so they could just be too big, 713 00:37:01,160 --> 00:37:04,520 Speaker 1: too heavy for us to discover them. In particle colliders, 714 00:37:04,800 --> 00:37:06,600 Speaker 1: remember to see something in the collider, you have to 715 00:37:06,640 --> 00:37:08,879 Speaker 1: put in enough energy, which means you have to make 716 00:37:08,920 --> 00:37:10,960 Speaker 1: the collider big enough, which means you have to get 717 00:37:11,080 --> 00:37:14,000 Speaker 1: enough money from the government to build a really big tunnel, 718 00:37:14,200 --> 00:37:17,720 Speaker 1: So there's a limitation there. This might be another way 719 00:37:17,800 --> 00:37:20,839 Speaker 1: to like sneak around that limitation and see these new 720 00:37:20,840 --> 00:37:23,600 Speaker 1: particles for the first time, at least hint that they're there. 721 00:37:24,120 --> 00:37:26,400 Speaker 1: And if you do the calculations and what do you 722 00:37:26,440 --> 00:37:29,200 Speaker 1: expect to see if there are these new particles, this 723 00:37:29,239 --> 00:37:32,000 Speaker 1: is kind of exactly what you expect to see. So 724 00:37:32,520 --> 00:37:34,600 Speaker 1: is the idea then that maybe there's a new part 725 00:37:34,680 --> 00:37:37,120 Speaker 1: that we don't know about that the photon is turning 726 00:37:37,200 --> 00:37:41,239 Speaker 1: into or like transforming into before it interacts with me. 727 00:37:41,719 --> 00:37:44,960 Speaker 1: Because the photon can interact with anything that has electric charge. 728 00:37:44,960 --> 00:37:47,560 Speaker 1: And so if there's some new heavy particle out there 729 00:37:47,600 --> 00:37:51,000 Speaker 1: that does have electric charge but it's never really exists 730 00:37:51,040 --> 00:37:54,120 Speaker 1: in the universe because it's too massive, well, occasionally the 731 00:37:54,120 --> 00:37:56,560 Speaker 1: photon can turn into it or pairs of it, like 732 00:37:56,760 --> 00:38:00,239 Speaker 1: it's particle and it's antiparticle, and that would change how 733 00:38:00,239 --> 00:38:02,720 Speaker 1: it interacts with the muan because you have to include 734 00:38:02,719 --> 00:38:05,440 Speaker 1: it in all of these calculations. Like maybe it admits 735 00:38:05,719 --> 00:38:08,040 Speaker 1: this new heavy particle and then it interacts with the 736 00:38:08,120 --> 00:38:11,239 Speaker 1: muan and then it reabsorbs that particle, and that would 737 00:38:11,320 --> 00:38:13,359 Speaker 1: change the way it interacts with the muan. And so 738 00:38:13,560 --> 00:38:17,760 Speaker 1: the presence of weird heavy particles changes the basic interaction 739 00:38:17,800 --> 00:38:20,920 Speaker 1: between two very simple particles, which I think is fascinating. 740 00:38:21,160 --> 00:38:23,719 Speaker 1: It's like a it's a clever way to leverage you 741 00:38:23,760 --> 00:38:26,080 Speaker 1: know something about the universe, to force the universe to 742 00:38:26,120 --> 00:38:28,600 Speaker 1: tell you about what's going on, even if you don't 743 00:38:28,600 --> 00:38:31,040 Speaker 1: have the energy to build that com eider. I think Danny, 744 00:38:31,080 --> 00:38:33,719 Speaker 1: what you're saying is that the experimentalist are right and 745 00:38:33,760 --> 00:38:36,840 Speaker 1: the theories are wrong. Well, you know, the experimentalists are 746 00:38:36,880 --> 00:38:41,320 Speaker 1: probably wrong in different ways from the theorists. Experimentalists definitely 747 00:38:41,360 --> 00:38:44,160 Speaker 1: make mistakes. It's really hard to do these things and 748 00:38:44,200 --> 00:38:46,359 Speaker 1: to get them right and to remove all sources of air. 749 00:38:46,880 --> 00:38:49,120 Speaker 1: And that's why it's fascinating as a cross check, because 750 00:38:49,200 --> 00:38:52,440 Speaker 1: if they're wrong, they're probably wrong in different directions or 751 00:38:52,560 --> 00:38:55,839 Speaker 1: different amounts. And so it's a great way to cross check, 752 00:38:55,880 --> 00:38:59,240 Speaker 1: and you know, to improve experimental physics and to improve 753 00:38:59,280 --> 00:39:02,640 Speaker 1: our theoretical understanding of the universe and maybe find new 754 00:39:02,680 --> 00:39:05,560 Speaker 1: particles in between. And yeah, and maybe make us stop 755 00:39:05,600 --> 00:39:08,799 Speaker 1: off in Stockholm to collect your Noobile prize. And that's 756 00:39:08,840 --> 00:39:11,439 Speaker 1: why you know this isn't over. It's not just like, oh, hey, 757 00:39:11,680 --> 00:39:15,040 Speaker 1: we saw this discripancy were done, because it's kind of indirect, right, 758 00:39:15,080 --> 00:39:17,160 Speaker 1: This is not like we make these particles, we see them, 759 00:39:17,200 --> 00:39:19,360 Speaker 1: we understand them. It's just sort of like a clue 760 00:39:19,400 --> 00:39:21,960 Speaker 1: that the particles are there. And so what they want 761 00:39:22,000 --> 00:39:24,000 Speaker 1: to do is make these things more precise. They want 762 00:39:24,000 --> 00:39:26,680 Speaker 1: to get better experimental measurements. They want to push the 763 00:39:26,680 --> 00:39:29,600 Speaker 1: theoretical measurements to see are these things wrong? Do these 764 00:39:29,640 --> 00:39:32,600 Speaker 1: stack up? Can we improve this uncertainty? Can we make 765 00:39:32,600 --> 00:39:35,120 Speaker 1: these things ten times as precise? And does it stick 766 00:39:35,160 --> 00:39:38,239 Speaker 1: around or disappear? All? Right? Well, I think it all 767 00:39:38,280 --> 00:39:41,280 Speaker 1: speaks to just again this idea that there may still 768 00:39:41,360 --> 00:39:44,480 Speaker 1: be amazing things hiding even in tiny little gaps of 769 00:39:44,520 --> 00:39:48,000 Speaker 1: point zero zero zero zero zero five six. That's right, 770 00:39:48,640 --> 00:39:50,560 Speaker 1: some of the biggest clues in the universe turn out 771 00:39:50,600 --> 00:39:53,360 Speaker 1: to be on the smallest numbers. And there is news 772 00:39:53,400 --> 00:39:56,360 Speaker 1: to come because there's an experiment happening right now again 773 00:39:56,400 --> 00:39:59,000 Speaker 1: in Chicago that's going to give a measurement of the 774 00:39:59,080 --> 00:40:02,080 Speaker 1: muan magnetic moment that's going to be four times as 775 00:40:02,120 --> 00:40:04,640 Speaker 1: precise as the one that we have now. They took 776 00:40:04,680 --> 00:40:06,879 Speaker 1: this big magnet and they shipped it from Long Island 777 00:40:06,920 --> 00:40:09,560 Speaker 1: where they did the experiment first, and moved into Chicago 778 00:40:10,000 --> 00:40:12,319 Speaker 1: and that a cleaner beam with more muans and they're 779 00:40:12,360 --> 00:40:15,640 Speaker 1: running those results right now. And in eighteen they said 780 00:40:15,640 --> 00:40:19,840 Speaker 1: that they would have results quote sometime in t and 781 00:40:19,920 --> 00:40:23,000 Speaker 1: so here we are in no results yet, but we 782 00:40:23,040 --> 00:40:26,200 Speaker 1: expect any day, any day. These things are hard. We 783 00:40:26,239 --> 00:40:28,920 Speaker 1: expect any day they'll come out with the new measurement. 784 00:40:29,000 --> 00:40:31,560 Speaker 1: And the whole physics community is waiting, like, what's going 785 00:40:31,640 --> 00:40:34,120 Speaker 1: to happen. How's the number going to change? So it's 786 00:40:34,120 --> 00:40:36,120 Speaker 1: a big deal. They're like, hey, we said we'd be 787 00:40:36,160 --> 00:40:39,359 Speaker 1: accurate about the muan, not about when we would tell 788 00:40:39,400 --> 00:40:44,840 Speaker 1: you about the plus or minus five years, plus the 789 00:40:44,880 --> 00:40:47,960 Speaker 1: minus fifty six years. Oh man, I'm sure that there 790 00:40:47,960 --> 00:40:50,520 Speaker 1: are some graduate students out there on this experiment it's 791 00:40:50,560 --> 00:40:53,279 Speaker 1: called muan G minus two, that they are sweating and 792 00:40:53,320 --> 00:40:55,920 Speaker 1: working hard to get this number out. Well, hopefully we 793 00:40:55,960 --> 00:40:58,640 Speaker 1: added a little bit more pressure because now I'm curious 794 00:40:58,680 --> 00:41:01,680 Speaker 1: about what's gonna happen. We're all curious because this is 795 00:41:01,719 --> 00:41:03,719 Speaker 1: how we learned about the universe. We corner it and 796 00:41:03,760 --> 00:41:05,759 Speaker 1: force it to tell us what is the answer to 797 00:41:05,800 --> 00:41:07,799 Speaker 1: this number? We think we know what it should be. 798 00:41:08,160 --> 00:41:11,040 Speaker 1: Tell us what the real truth is, tells the universe, 799 00:41:11,320 --> 00:41:14,480 Speaker 1: don't keep it to yourself. Experimental physics is basically a 800 00:41:14,520 --> 00:41:17,680 Speaker 1: modern day oracle, right, We actually do get to ask questions, 801 00:41:17,800 --> 00:41:19,960 Speaker 1: will be horrible, and it gives us answer and then 802 00:41:20,000 --> 00:41:22,920 Speaker 1: it chops off your head or something something Greek and 803 00:41:23,000 --> 00:41:27,480 Speaker 1: classical like that. It kills your mom. Probably all right, Well, 804 00:41:27,480 --> 00:41:29,880 Speaker 1: we hope you enjoyed that, and think about all the 805 00:41:29,960 --> 00:41:33,440 Speaker 1: amazing secrets that could be hiding in the smallest of quantities. 806 00:41:33,560 --> 00:41:35,200 Speaker 1: That's right. In one of these days, one of these 807 00:41:35,200 --> 00:41:38,240 Speaker 1: secrets will reveal something deep and true about the universe. 808 00:41:38,239 --> 00:41:48,480 Speaker 1: See you next time. Thanks for listening, and remember that 809 00:41:48,560 --> 00:41:51,320 Speaker 1: Daniel and Jorge Explain the Universe is a production of 810 00:41:51,440 --> 00:41:54,800 Speaker 1: I Heart Radio. Or more podcast from my Heart Radio 811 00:41:54,960 --> 00:41:58,520 Speaker 1: visit the i heart Radio app, Apple Podcasts, or wherever 812 00:41:58,640 --> 00:41:59,920 Speaker 1: you listen to your favorite