WEBVTT - What is Mirror Matter? 0:00:08.280 --> 0:00:11.600 Hey, Daniel, I have a question. The particles have families. 0:00:12.119 --> 0:00:17.080 Oh yeah, actually each particle has a whole set of relatives. Really, 0:00:17.160 --> 0:00:21.360 so who is the electrons closest cousin? Well, the positron 0:00:21.520 --> 0:00:25.200 is kind of like the electrons evil twin. Does you 0:00:25.280 --> 0:00:29.880 have like a twurly mustache? Or whereas where is the 0:00:29.880 --> 0:00:34.200 opposite color clothes? Yeah, and then it's got the muan, 0:00:34.400 --> 0:00:37.440 which is like it's heavier cousin, it's more massive cousin, 0:00:38.640 --> 0:00:41.239 Like it's more fit, like it's bulky or does it 0:00:41.280 --> 0:00:44.840 just sit around and eat bananas? Nobody knows? Nobody knows. 0:00:45.200 --> 0:00:50.160 And then the electron even has like hypothetical relatives. What 0:00:50.440 --> 0:00:53.760 you mean, like long lost relatives. Yeah. Like there might 0:00:53.800 --> 0:00:57.279 be a super symmetric version of the electron. We call 0:00:57.360 --> 0:01:00.440 it the selectron. That sounds like a great suit for power. 0:01:00.440 --> 0:01:20.040 I'd love to select my own relatives. I'm or Hand, 0:01:20.120 --> 0:01:24.120 a cartoonists and the creator of PhD comics. I'm Daniel. 0:01:24.319 --> 0:01:27.720 I'm a particle physicist, and there is no super symmetric 0:01:27.840 --> 0:01:30.600 version of me. Is there an asymmetrical version of you? 0:01:30.720 --> 0:01:33.320 I don't know, but if there was a super symmetric version, 0:01:33.360 --> 0:01:38.280 it would be the Daniel or the Daniel Leno, the 0:01:38.400 --> 0:01:41.679 Daniel Tron. I'm sure you would come up with an 0:01:41.720 --> 0:01:44.800 awesome name for that version of Daniel. Welcome to our 0:01:44.800 --> 0:01:47.960 podcast Daniel and Jorge Explain the Universe, a production of 0:01:48.000 --> 0:01:50.280 I Heart Radio in which we take you on a 0:01:50.400 --> 0:01:54.040 mental tour of everything that's amazing, that's wonderful, that inspires 0:01:54.080 --> 0:01:57.400 your curiosity, everything that makes you wonder how does that work? 0:01:57.480 --> 0:02:00.360 Why is it like that? Why isn't it some other way? 0:02:00.640 --> 0:02:02.720 We take the whole universe and try to break it 0:02:02.760 --> 0:02:05.440 down into time little pieces and explain them to you, 0:02:05.960 --> 0:02:07.680 and we try to take you in a tour of 0:02:07.720 --> 0:02:09.799 all the things that are out there, all the amazing 0:02:09.800 --> 0:02:15.560 and incredible types of objects like black holes and neutron stars, 0:02:15.639 --> 0:02:19.520 and all of the incredible and mysterious particles that are 0:02:19.520 --> 0:02:22.840 out there and then might be out there. That's right, 0:02:22.880 --> 0:02:25.640 because part of the journey of understanding the universe is 0:02:25.680 --> 0:02:28.640 thinking about what's there and what might be there. What 0:02:28.720 --> 0:02:31.480 would make more sense if the universe had it in it. 0:02:31.720 --> 0:02:34.200 What do we need to add to our vision of 0:02:34.240 --> 0:02:36.760 the universe to make it make more sense? What puzzle 0:02:36.840 --> 0:02:40.920 pieces are we missing? Because that's how scientists explore, right, 0:02:40.960 --> 0:02:43.480 I know. That's how we kind of probe the unknown. 0:02:43.600 --> 0:02:45.600 We as we sit around and we think, well, well, 0:02:45.600 --> 0:02:47.680 I guess you guys sit around on and I went 0:02:47.760 --> 0:02:50.000 some coffee, and you try to think of what would 0:02:50.040 --> 0:02:52.120 be what could be out there, what would make sense 0:02:52.160 --> 0:02:54.960 in terms of the what the equations predict and what 0:02:55.800 --> 0:02:58.799 the data suggests, and and try to think about what 0:02:58.840 --> 0:03:01.359 we can discover out there and universe. Yeah, there's sort 0:03:01.400 --> 0:03:04.119 of two ways to make big discoveries in physics. One 0:03:04.240 --> 0:03:07.120 is like try to anticipate them, to look at the 0:03:07.160 --> 0:03:10.079 pattern of what we know and say, what's missing? Would 0:03:10.120 --> 0:03:13.000 this make more sense if we had another piece? Like 0:03:13.040 --> 0:03:14.679 if you were doing a puzzle and you fill the 0:03:14.720 --> 0:03:17.040 whole thing in, is one piece missing? You're going to 0:03:17.120 --> 0:03:18.640 go out and look for that one piece and you 0:03:18.720 --> 0:03:21.000 know sort of what to look for, you have expected it. 0:03:21.480 --> 0:03:23.800 The other way to make discoveries just to like go 0:03:23.919 --> 0:03:26.000 out there is an explore and see what you're find 0:03:26.040 --> 0:03:28.640 and maybe you're run into something amazing you didn't expect. 0:03:28.960 --> 0:03:31.440 That's also fun, But there's a lot of times that 0:03:31.480 --> 0:03:33.919 we can't just do that. We don't have necessarily the 0:03:33.960 --> 0:03:35.680 way to explore. We have to think about it in 0:03:35.720 --> 0:03:38.160 advance and try to figure out in advance what is 0:03:38.200 --> 0:03:40.760 it we should be looking for. I usually find my 0:03:40.760 --> 0:03:45.760 puzzle pieces in between my couch cushions, or or under 0:03:45.800 --> 0:03:48.800 the or on the table. I borrowed a bunch of 0:03:48.840 --> 0:03:51.200 puzzles from some friends and I put the first one 0:03:51.240 --> 0:03:54.760 together and it was missing a piece, and it had 0:03:54.760 --> 0:03:57.800 an extra piece from another one of the puzzles. What 0:03:58.360 --> 0:04:00.280 I think your friends are trying to drive you crazy 0:04:00.280 --> 0:04:02.520 to think so, because then the next puzzle was the same. 0:04:02.960 --> 0:04:05.360 So by the time the next puzzle, I had this 0:04:05.520 --> 0:04:08.640 like two extra random pieces and two puzzles each missing 0:04:08.680 --> 0:04:12.680 a piece. And it wasn't symmetric LIKEE was missing from 0:04:12.720 --> 0:04:14.480 the other one. No, it was like a cycle. It 0:04:14.560 --> 0:04:16.640 was like you have to finish all six to finish 0:04:16.680 --> 0:04:19.120 any of them. It was torture. Um, I think they're 0:04:19.120 --> 0:04:21.640 trying to gas light you in the puzzle version of 0:04:21.720 --> 0:04:24.960 gas lighting, trying to puzzle light you down exactly. But 0:04:25.040 --> 0:04:26.320 you know, I have to take issue with what you 0:04:26.360 --> 0:04:28.800 said earlier that physicists, when we try to have ideas, 0:04:28.839 --> 0:04:31.680 we sit around and think about stuff. Why is that 0:04:31.760 --> 0:04:34.000 you think about It's just like sitting around these days 0:04:34.240 --> 0:04:36.200 trying to do my thinking. Well, I'm active, I'm going 0:04:36.240 --> 0:04:38.520 for a walk to think about stuff. I'm doing jumping 0:04:38.600 --> 0:04:41.320 jack to think up new theories. I thought you were 0:04:41.320 --> 0:04:43.320 going to complain that you actually lie down when you 0:04:43.360 --> 0:04:46.839 think physics. Is that how you get your creative ideas? 0:04:47.080 --> 0:04:51.279 Curl up under the desk or something. My best ideas 0:04:51.320 --> 0:04:54.799 come when I have my feed up. For sure. Post 0:04:54.960 --> 0:04:57.600 definitely leads to creativity. Yeah. So we know a lot 0:04:57.640 --> 0:04:59.440 about the universe, and we know all a lot of 0:04:59.480 --> 0:05:02.000 the particles that are out there that make up matter, 0:05:02.200 --> 0:05:05.560 that might make up matter, and that um make up 0:05:05.600 --> 0:05:08.520 other things that maybe are not as useful to the universe. 0:05:09.000 --> 0:05:11.560 But there are also a lot of missing pieces in 0:05:11.920 --> 0:05:15.800 the universe. There's a lot of empty places in our 0:05:15.839 --> 0:05:18.960 ideas of particles and matter that could be filled by 0:05:19.200 --> 0:05:22.520 new particles. That's right, because when we look at the particles, 0:05:22.560 --> 0:05:24.960 we don't just want to make a list and say here, 0:05:25.040 --> 0:05:27.640 all the particles in the universe were done. We want 0:05:27.640 --> 0:05:29.800 to understand that. We want to fit them together into 0:05:29.800 --> 0:05:33.280 patterns because those patterns are clues, clues that will lead 0:05:33.360 --> 0:05:35.599 us to be able to pull back a layer of 0:05:35.600 --> 0:05:39.279 reality and see what's underneath those particles, what are the tiny, 0:05:39.320 --> 0:05:42.600 even smaller particles that make them up all the way 0:05:42.640 --> 0:05:45.320 down to the smallest bits of the universe. So the 0:05:45.320 --> 0:05:47.360 way to do that is to organize our knowledge and 0:05:47.480 --> 0:05:50.720 look for holes. For example, before we discover the top cork, 0:05:51.080 --> 0:05:53.920 we had five corks and they fit together in two 0:05:53.960 --> 0:05:57.240 pairs plus one lonely bottom cork, And we thought, where's 0:05:57.279 --> 0:05:59.960 the partner for the bottom cork? It must be out there, 0:06:00.200 --> 0:06:02.280 and we went and looked for it and found it. 0:06:02.600 --> 0:06:04.960 So this strategy of organizing our knowledge and looking for 0:06:05.040 --> 0:06:08.320 holes and gaps and symmetries is a really productive way 0:06:08.400 --> 0:06:10.960 to find new things. And so today on the program, 0:06:11.000 --> 0:06:15.440 we'll be talking about one such set of wholly particles 0:06:15.440 --> 0:06:17.760 that might exist and that might answer a lot of 0:06:17.839 --> 0:06:21.680 questions about our understanding of the universe. So we'll be 0:06:21.720 --> 0:06:31.160 asking the question, what is mirror matter and why is 0:06:31.200 --> 0:06:33.680 it so hard to say? It is a little hard 0:06:33.720 --> 0:06:35.640 to say. I feel a little punk tight just saying 0:06:35.720 --> 0:06:38.960 mirror matter mirror Well, you know, there's an a whole 0:06:38.960 --> 0:06:42.440 sociological question we'll dig into later about why mirror matter 0:06:42.640 --> 0:06:46.040 is not so popular among theoretical physicists. But One answer 0:06:46.120 --> 0:06:47.960 might be that it's just kind of hard to say. 0:06:49.400 --> 0:06:52.039 Do you think that matters? It's more fun to say 0:06:52.160 --> 0:06:56.880 dark matter antimatter than mirror matter. Don't, don't, don't use 0:06:56.960 --> 0:06:59.960 alliteration when you when you discover something new and amaze 0:07:00.000 --> 0:07:02.279 in physics, you know what you're saying and ours ours 0:07:02.279 --> 0:07:05.920 are just horror to say their horror, horror. There there 0:07:05.920 --> 0:07:12.760 are harder horror choice exactly? Is that why particle physics 0:07:12.800 --> 0:07:16.040 has some problems there? Yeah? I think so? All right? So, 0:07:16.120 --> 0:07:19.240 as usual, Daniel went out there into the wiles of 0:07:19.280 --> 0:07:21.880 the Internet to ask if people were familiar with this 0:07:22.000 --> 0:07:25.280 idea of mirror matter. So thanks to everybody who sent 0:07:25.400 --> 0:07:28.640 in their speculations about what mirror matter might be. If 0:07:28.680 --> 0:07:31.640 you'd like to speculate on a future topic of one 0:07:31.640 --> 0:07:34.920 of our podcast episodes, please write to us two questions 0:07:35.000 --> 0:07:37.960 at Daniel and Jorge dot com. We'd love to have 0:07:38.120 --> 0:07:40.360 you participate. So think about it for a second before 0:07:40.360 --> 0:07:43.560 you listen to these answers. If someone ask you what 0:07:43.800 --> 0:07:46.320 is mirror matter, or ask you how to pronounce it? 0:07:46.560 --> 0:07:50.240 For that matter, what would you say? There is what 0:07:50.280 --> 0:07:54.120 people had to say something that reflected um like a 0:07:54.200 --> 0:07:56.560 positive trium versus uh. You know, it's kind of the 0:07:56.600 --> 0:07:59.160 opposite of each of the particles that we have. I 0:07:59.240 --> 0:08:02.960 can only guess, and the name probably it's the matter 0:08:03.080 --> 0:08:08.880 that imitates the matter that comes close to or get 0:08:09.320 --> 0:08:13.800 gets in contact with. I have no idea. So there 0:08:13.840 --> 0:08:16.680 are two things that come to my mind immediately. The 0:08:16.720 --> 0:08:20.720 first one is antimater, but I think that this answer 0:08:20.800 --> 0:08:22.720 is to straightforward, so I don't think this is the 0:08:22.800 --> 0:08:25.920 right concept to your question. So the second thing that 0:08:26.000 --> 0:08:31.240 comes to my mind, that's supersymmetry. I assume that mirror 0:08:31.280 --> 0:08:34.280 matter talks about particle physics, and I don't know a 0:08:34.280 --> 0:08:38.199 whole lot about it, but from what I know, I 0:08:38.240 --> 0:08:45.280 think mirror matter wants to kind of explain why the 0:08:45.320 --> 0:08:47.880 weak force is the only one that does not respect 0:08:48.240 --> 0:08:52.680 the mirror reflection symmetry That sounds made up, sounds like 0:08:52.760 --> 0:08:55.120 something i'd hear on Star Trek, but I'm gonna go 0:08:55.280 --> 0:09:00.000 with it relates to supersymmetry. Those are words I've heard before, 0:09:00.080 --> 0:09:04.120 or I wouggest that mirror matter is matter with the 0:09:04.160 --> 0:09:09.880 opposite handedness. Mirror matter is maybe matter with particles of 0:09:10.320 --> 0:09:15.439 opposite spin in charge. I'm immediately thinking of anti matter, 0:09:15.520 --> 0:09:19.720 but I'm presuming it's something different, all right. I like 0:09:19.800 --> 0:09:24.800 the star Trek reference. We should be writing for star Trek, Daniel. 0:09:25.600 --> 0:09:28.480 Star Trek is just stealing from reality. You know, reality 0:09:28.520 --> 0:09:32.040 is so weird that inspires hilarious fiction. But people seem 0:09:32.080 --> 0:09:34.200 to have sort of the idea that it's like a matter, 0:09:34.320 --> 0:09:36.880 but it's somehow their mirror image. So I guess it 0:09:36.960 --> 0:09:39.040 is a pretty good name. Kind of like there's some 0:09:39.120 --> 0:09:44.560 kind of idea about symmetry and handedness and spin, and 0:09:44.640 --> 0:09:47.360 there seems to be a general understanding that there are 0:09:47.400 --> 0:09:50.440 these symmetries that everything we know could be reflected. There 0:09:50.440 --> 0:09:53.040 could be a whole other set of stuff, and exactly 0:09:53.040 --> 0:09:55.040 the way that there are is anti matter. Now we're 0:09:55.040 --> 0:09:57.040 talking a moment about what mirror matter is. It's not 0:09:57.120 --> 0:09:59.480 the same thing as anti matter, but it does share 0:09:59.520 --> 0:10:02.000 that thing in common that it's a reflection of the 0:10:02.040 --> 0:10:05.400 particles we know. It tells us something about the symmetries 0:10:05.440 --> 0:10:07.680 that are built into the universe and the ideas that 0:10:07.720 --> 0:10:10.839 there's potentially more than one of these reflections, you know, 0:10:10.920 --> 0:10:14.000 the reflection of all the matter particles into antimatter particles. 0:10:14.240 --> 0:10:17.160 And you can also have the reflection potentially of matter 0:10:17.200 --> 0:10:20.120 particles into these mirror matter particles. So it's in the 0:10:20.200 --> 0:10:22.880 same sort of family of ideas, but it's just a 0:10:22.880 --> 0:10:26.319 different kind of reflection. Man, I feel like we were 0:10:26.360 --> 0:10:29.400 living in a house of mirrors or a universe of mirrors. 0:10:29.440 --> 0:10:32.400 It's crazy and it's amazing, and it blows my mind 0:10:32.440 --> 0:10:35.040 how many of these reflections there are. Because you know, 0:10:35.040 --> 0:10:37.440 we talked about antimatter, and we will talk about mirror matter, 0:10:37.679 --> 0:10:39.680 but then there are also these particle families, Like the 0:10:39.720 --> 0:10:43.199 electron is not just reflected into the muon, it's reflected 0:10:43.240 --> 0:10:46.280 into the muan and the tao. And so the whole 0:10:46.320 --> 0:10:49.559 structure that we understand of the universe of particle physics 0:10:49.840 --> 0:10:52.560 is really built around all these symmetries and reflections. I mean, 0:10:52.679 --> 0:10:55.400 that's what we're trying to do, is like organize these 0:10:55.400 --> 0:10:57.840 things into patterns, and the look at the patterns and say, 0:10:57.960 --> 0:11:01.800 what does that pattern mean about the universe? Means that 0:11:01.920 --> 0:11:04.880 maybe you shouldn't have decorated your whole universe with mirrors. 0:11:05.160 --> 0:11:09.040 Perhaps you know who did, right? Who put up all 0:11:09.080 --> 0:11:12.160 these mirrors? Right? This place is like a crazy fun house. 0:11:12.160 --> 0:11:15.319 Why is it so hard to understand? No, it's it's fascinating, 0:11:15.360 --> 0:11:17.280 you know, just like you can ask the question, you know, 0:11:17.600 --> 0:11:19.680 why is there no antimatter left in the universe. You 0:11:19.679 --> 0:11:21.520 can ask the question like, well, why do we have 0:11:21.559 --> 0:11:24.840 antimatter at all? Right? Why is there this symmetry? What 0:11:24.880 --> 0:11:27.120 does it mean about the universe that there seems to 0:11:27.120 --> 0:11:30.080 be this balance in the list of particles, but not 0:11:30.160 --> 0:11:33.760 in their actual existence, right and so so and some 0:11:33.800 --> 0:11:36.960 people also mentioned the idea of supersymmetry, But mirror matter 0:11:37.080 --> 0:11:40.360 is not related to supersymmetry, right, that's right. Supersymmetry is 0:11:40.400 --> 0:11:44.240 yet another hypothetical reflection and that looks to try to 0:11:44.280 --> 0:11:47.000 build a symmetry into the universe. It says, we have 0:11:47.120 --> 0:11:50.320 some particles called fermions and make up matter particles, and 0:11:50.400 --> 0:11:53.800 other particles called bosons that make up forces like photons 0:11:53.840 --> 0:11:56.400 and z bosons. What if each of those has a 0:11:56.440 --> 0:12:00.079 corresponding particle on the other side, Every fermion has some 0:12:00.240 --> 0:12:03.920 boson that corresponds to it, So the electron has a selectron, 0:12:04.000 --> 0:12:06.840 and the mulan has a smew on, And then every 0:12:06.880 --> 0:12:10.000 boson like the photon, has a fermion partner. So the 0:12:10.440 --> 0:12:13.640 photon would have a photino and the w particle would 0:12:13.640 --> 0:12:16.800 have a we know, for example, and so that again 0:12:16.920 --> 0:12:20.440 just reflects the whole set of standard model particles over 0:12:20.480 --> 0:12:22.840 into a new set of hypothetical particles that we have 0:12:22.960 --> 0:12:25.679 not yet discovered and are not the same as antimatter 0:12:25.880 --> 0:12:28.560 and not the same as mirror matter. It's just another 0:12:29.120 --> 0:12:31.760 kind of reflection that tells you about how we're always 0:12:31.760 --> 0:12:35.080 looking for symmetries in the universe. But this one seems 0:12:35.080 --> 0:12:38.200 to claim the mantle of mirror matter, Like it just 0:12:38.240 --> 0:12:40.559 grabs that word and says, I'm the I'm the mirror 0:12:41.000 --> 0:12:44.959 type of matter. Yeah, exactly, and it's mostly championed by 0:12:45.040 --> 0:12:50.840 like one guy in Australia. Wait. Wait, this is a 0:12:50.880 --> 0:12:56.040 major physics theory that has a support of exactly one physicists, 0:12:56.080 --> 0:12:59.240 not exactly one physicist. But you know, um, not that 0:12:59.280 --> 0:13:02.800 many physicist believe in mirror matter. Although other people have 0:13:02.920 --> 0:13:05.240 ideas that are very similar to mirror matter, they just 0:13:05.280 --> 0:13:07.880 don't call it that. So maybe it's just the naming issue. 0:13:07.920 --> 0:13:09.880 People like, we hate that name. We're gonna come up 0:13:09.880 --> 0:13:13.480 with a similar idea and call it something else. Yeah, 0:13:13.480 --> 0:13:16.240 you're telling me that this idea also has other names, 0:13:16.360 --> 0:13:19.800 like alice matters, or shadow matter. Yeah, that's that's all 0:13:19.800 --> 0:13:22.880 the same one idea with several different potential names. So 0:13:22.920 --> 0:13:25.520 I guess, you know, the community around mirror matter was 0:13:25.520 --> 0:13:27.480 trying out a few things to see what would stick, 0:13:27.800 --> 0:13:29.760 and I guess mirror matter is the most popular. I 0:13:29.800 --> 0:13:31.640 kind of like alice matter because it has the like 0:13:31.880 --> 0:13:35.800 literary reference to it. I like shadow matter. It sounds 0:13:35.800 --> 0:13:39.520 like something out of Dungeons and Dragons. You're gonna roll 0:13:39.559 --> 0:13:42.360 a die and try to use your shadow matter sword. Yeah, 0:13:42.920 --> 0:13:46.760 the shadow mage uses a shadow matter sword. Of course. 0:13:46.880 --> 0:13:48.720 I think it's too similar to dark matter, you know, 0:13:48.720 --> 0:13:50.880 because then people are like, well, if you put matter 0:13:51.000 --> 0:13:53.640 in the shadows, does it become dark matter? You know, 0:13:53.640 --> 0:13:56.320 it's very confusing. All right, well let's jump right into 0:13:56.440 --> 0:14:00.200 Daniel what let's answer the question what is mirror better. 0:14:00.280 --> 0:14:02.240 I'm guessing it has to do it's sort of like 0:14:02.280 --> 0:14:05.080 supersymmetric matter. But maybe you're saying it's a different kind 0:14:05.080 --> 0:14:08.160 of mirror. Yeah, it's a different kind of mirror. So 0:14:08.200 --> 0:14:11.280 whenever we create a new set of hypothetical particles to 0:14:11.400 --> 0:14:14.760 balance the particles we have, it's because we see an imbalance, 0:14:15.040 --> 0:14:17.640 we see something asymmetric, and we wonder why do we 0:14:17.679 --> 0:14:20.560 have positive charge particles and not negative for example, Or 0:14:20.760 --> 0:14:23.000 you know, why do we have fermion matter and boson 0:14:23.080 --> 0:14:26.680 forces not the opposite. So in this case, we've created 0:14:26.680 --> 0:14:29.280 a whole new set of particles, the mirror particles, to 0:14:29.320 --> 0:14:32.440 try to balance the parity asymmetry of the universe, the 0:14:32.520 --> 0:14:35.560 symmetry about being reflected in the mirror? Does the universe 0:14:35.560 --> 0:14:38.360 look the same when you reflected in the mirror? And 0:14:38.400 --> 0:14:40.880 we've talked on the podcast several times about how our 0:14:41.000 --> 0:14:44.760 universe seems to be weirdly left handed, like some parts 0:14:45.040 --> 0:14:48.000 of the standard model, the forces that are involved like 0:14:48.160 --> 0:14:50.280 to only talk to particles that are left handed and 0:14:50.360 --> 0:14:52.600 not right handed, and that's weird. I guess it all 0:14:52.640 --> 0:14:55.800 sort of goes back to the concept of particles and 0:14:55.880 --> 0:15:00.800 matter having um like properties or values of things charge 0:15:01.000 --> 0:15:05.800 or color or what's the other one, spin spin, favor, 0:15:06.640 --> 0:15:09.920 spin flavorite. They have all these properties and so, and 0:15:10.040 --> 0:15:12.760 really in the math you can just flip them and 0:15:13.480 --> 0:15:16.760 such a particle could still exist. Like mathematically you can 0:15:16.800 --> 0:15:19.960 flip these things, even though you may not necessarily see 0:15:20.000 --> 0:15:22.680 them in nature. Right, That's kind of the idea, is 0:15:22.720 --> 0:15:25.320 that particles has these properties, and you can flip some 0:15:25.400 --> 0:15:27.960 of them, and sometimes you see particles that have them, 0:15:28.000 --> 0:15:30.800 and sometimes you don't see particles that have them. Yeah, 0:15:30.880 --> 0:15:33.960 that's exactly right. We look at the structure of our 0:15:34.160 --> 0:15:36.760 theory and we wonder if it's symmetric. We're like, well, 0:15:36.800 --> 0:15:38.800 what happens if you flip all these things? You know, 0:15:38.800 --> 0:15:41.680 if you flip the charges from positive negative, or you 0:15:42.120 --> 0:15:44.840 flip everything for the minus z access to the positive 0:15:44.880 --> 0:15:47.880 z axis, or you run time backwards, and all these things. 0:15:47.880 --> 0:15:50.520 We wonder, like, is our theory symmetric? And so as 0:15:50.560 --> 0:15:52.360 you say, you can take this this set of particles 0:15:52.360 --> 0:15:54.200 and you can say, well, do we have the opposite 0:15:54.240 --> 0:15:56.640 set in this sense or in this other sense, or 0:15:56.680 --> 0:15:58.880 in this third sense? Do we have the opposite set? 0:15:59.240 --> 0:16:02.240 You know, do exist? And if not, then why not? 0:16:02.400 --> 0:16:04.640 Because that tells you something about the universe, right, like 0:16:04.880 --> 0:16:07.960 why do we only have negatively charged electrons and not 0:16:08.080 --> 0:16:12.280 positively charged electrons, you know, positrons? And so it's it's 0:16:12.320 --> 0:16:14.800 interesting because you feel like there must be a reason. 0:16:14.840 --> 0:16:17.440 We like to think that that the universe should be symmetric, 0:16:17.560 --> 0:16:21.040 because that makes sense because if it's asymmetric, then like 0:16:21.120 --> 0:16:24.440 who made that choice? Right, why matter or not antimatter? 0:16:24.640 --> 0:16:27.080 Did somebody flip a coin? Is it totally random? And 0:16:27.120 --> 0:16:28.880 we don't like that. In physics, we don't like things 0:16:28.920 --> 0:16:31.520 that don't have explanations, So we like things to be 0:16:31.520 --> 0:16:34.720 symmetric because then then they don't need explanations. So we 0:16:34.760 --> 0:16:36.840 take our theory, we look for all the things that 0:16:36.880 --> 0:16:38.920 are asymmetric, and then we try to fill in those holes. 0:16:39.200 --> 0:16:40.680 But I guess when when you know, why do physics 0:16:40.800 --> 0:16:44.160 have a preference for symmetry, like um, when you couldn't 0:16:44.160 --> 0:16:47.040 you ask the same question like who made the universe symmetric? 0:16:47.200 --> 0:16:50.160 Like if the universe was symmetric, wouldn't you ask the 0:16:50.200 --> 0:16:53.320 same question? That's a great question, and that really goes 0:16:53.360 --> 0:16:56.680 to philosophy. Um, And it's a question of what's simple. 0:16:57.000 --> 0:16:58.840 You know, when we look at a physics theory, we 0:16:58.960 --> 0:17:01.760 have questions about it. And when we compare two different 0:17:01.760 --> 0:17:04.399 physics theories, we want the one that's simpler, that needs 0:17:04.640 --> 0:17:08.399 like less explanation and fewer ideas. And that's sort of um. 0:17:08.600 --> 0:17:11.040 You know, we don't know why the universe is that way, 0:17:11.080 --> 0:17:13.000 but it does seem to work that way. That's simpler 0:17:13.040 --> 0:17:16.800 ideas seem to work best, and so I would just 0:17:16.880 --> 0:17:20.119 ask fewer questions about a theory that was symmetric than 0:17:20.160 --> 0:17:23.600 the theory that was asymmetric, because a theory that's symmetric, 0:17:23.640 --> 0:17:26.159 you're right, there's no reason why the universe has to 0:17:26.200 --> 0:17:29.280 be symmetric. But it just seems to make more sense 0:17:29.320 --> 0:17:32.439 intuitively or or aesthetically. But you know, that's not a 0:17:32.440 --> 0:17:34.879 scientific feeling at all. That's sort of like a philosophical 0:17:35.440 --> 0:17:39.800 um um or personal aesthetic feeling. Yeah, that's what I mean. 0:17:39.840 --> 0:17:41.680 It's like if one of your kids was really well 0:17:41.720 --> 0:17:43.879 behaved on the other one was a lot of trouble, 0:17:43.880 --> 0:17:45.679 and you'd be like, yeah, that that makes sense in 0:17:45.720 --> 0:17:53.160 the universal cosmic balanced sense. I think there is something there, though, 0:17:53.200 --> 0:17:55.679 because if the universe is asymmetric, there are lots of 0:17:55.680 --> 0:17:58.120 ways it could be asymmetric, but there's only really one 0:17:58.160 --> 0:18:01.399 way to be symmetric. And so if you're asymmetric, and 0:18:01.400 --> 0:18:03.440 you're asymmetric in one particular way, then you have to 0:18:03.440 --> 0:18:06.280 wonder why are we living in a multiverse where every 0:18:06.359 --> 0:18:09.680 choice for that asymmetry is made. Are there other universes 0:18:09.720 --> 0:18:12.320 out there that are antimatter instead of matter, for example, 0:18:12.760 --> 0:18:14.919 or are we living in a simulation where this was 0:18:14.960 --> 0:18:17.520 decided by the people who ran the simulation. It's just 0:18:17.520 --> 0:18:20.280 sort of unsatisfying to not have an explanation if there 0:18:20.280 --> 0:18:22.719 are lots of options, whereas if there's only one option, 0:18:22.920 --> 0:18:24.679 then you know that's just the option. You can ask like, 0:18:24.760 --> 0:18:27.879 why is there only that option? And that's a deeper question, 0:18:28.200 --> 0:18:30.639 like if both your kids are well behaved, you'd be suspicious. 0:18:31.880 --> 0:18:34.680 I'd give my wife credit if that was the case. Unfortunately, 0:18:34.720 --> 0:18:39.960 we don't live in that universe. Al right. Well, okay, 0:18:39.960 --> 0:18:43.119 so mirror matter, then, is a matter that also breaks 0:18:43.160 --> 0:18:45.920 one of these symmetries in nature that you have, and 0:18:46.080 --> 0:18:49.159 it's sort of related to the weak force, right. I 0:18:49.280 --> 0:18:52.200 find it a little confusing to think about parody because 0:18:52.520 --> 0:18:55.600 it's hard to think about whether it matters if you're 0:18:55.600 --> 0:18:59.200 reflected in the mirror, whether the universe prefers right handed 0:18:59.280 --> 0:19:02.240 or left handed. Now it's the same basic concept, but 0:19:02.440 --> 0:19:05.240 I think it's easier to think about whether it matters 0:19:05.280 --> 0:19:08.560 if you rotate your experiment, whether the universe has a 0:19:08.600 --> 0:19:12.919 preferred direction, which seems obviously crazy. Imagine you throw a 0:19:12.920 --> 0:19:15.880 ball and it follows some law of physics, right, parabolo 0:19:15.960 --> 0:19:17.879 goes up and it comes down. Now you watch that 0:19:17.960 --> 0:19:19.920 same ball toss, but now you're standing on your head. 0:19:20.400 --> 0:19:23.760 It looks a little different, right because you're you've rotated yourself, 0:19:24.320 --> 0:19:26.800 But the same laws apply, and like you can still 0:19:26.800 --> 0:19:29.320 apply the laws of physics to the ball. Moving shouldn't 0:19:29.320 --> 0:19:32.399 matter if you're standing on your head, right, except that 0:19:32.480 --> 0:19:35.400 now down means up and up means down. Yeah, exactly, 0:19:35.600 --> 0:19:37.199 you have to put some minus signs in there, but 0:19:37.240 --> 0:19:40.040 the same laws do apply. Now you don't see exactly 0:19:40.080 --> 0:19:42.600 the same thing, Like it looks different if you're standing 0:19:42.600 --> 0:19:45.639 on your head, but the same rules apply. And so 0:19:45.760 --> 0:19:48.359 parody is sort of like that, like if you reflect 0:19:48.440 --> 0:19:51.760 something into the mirror, do the same rules apply or not? 0:19:52.280 --> 0:19:54.240 And people for a long time thought, well, of course, 0:19:54.480 --> 0:19:56.360 like just because you're doing in the mirror, the same 0:19:56.440 --> 0:19:59.719 rules should apply. Like it would be nonsense if our 0:19:59.800 --> 0:20:02.879 you niverse was somehow left handed and it looked different 0:20:02.920 --> 0:20:04.879 in the mirror, and like the mirror was right handed, 0:20:05.200 --> 0:20:07.600 it would be weird. They would be weird. And people 0:20:07.960 --> 0:20:10.400 just assumed for like, you know, as long as people 0:20:10.440 --> 0:20:13.080 had this idea, until about fifty years ago, people assumed 0:20:13.320 --> 0:20:15.520 the universe was symmetric in the mirror that if you 0:20:15.520 --> 0:20:18.000 didn't experiment, it would look the same in the mirror 0:20:18.240 --> 0:20:20.199 that you know that the mirrors that in the in 0:20:20.240 --> 0:20:22.840 the mirror world, the same laws of physics would apply. 0:20:23.119 --> 0:20:25.359 Now we can't actually go to the mirror world. We 0:20:25.359 --> 0:20:28.439 can't do the mirror experiment. Right, the ideas we do 0:20:28.800 --> 0:20:31.560 experiments in our universe and we think about what they 0:20:31.560 --> 0:20:33.359 would look like in the mirror world. We try to 0:20:33.640 --> 0:20:36.080 we imagine that all the experiments we do in our 0:20:36.200 --> 0:20:40.359 universe would look the same in the mirror world. But 0:20:40.359 --> 0:20:43.840 but he neverse is a little bit weirder than that. 0:20:43.880 --> 0:20:47.000 The universe is super duper weird in fact, and it 0:20:47.040 --> 0:20:49.240 was about fifty years ago the people realized, you know, 0:20:49.280 --> 0:20:52.240 we never actually checked to see if this is true 0:20:52.520 --> 0:20:54.920 for all the different kinds of interactions. They had checked 0:20:54.920 --> 0:20:58.000 for the strong force, they had checked for electromagnetism, and 0:20:58.280 --> 0:21:01.480 parody was preserved like everything a perfect sense, but nobody 0:21:01.480 --> 0:21:05.000 had actually checked for the week interaction. And then one 0:21:05.080 --> 0:21:08.240