WEBVTT - Listener Questions 9 0:00:09.039 --> 0:00:12.440 Hey, Jorney, Maybe you're not aware of you recently coined 0:00:12.440 --> 0:00:15.600 a word that I now use all the time. Oh yeah, 0:00:15.600 --> 0:00:17.599 I've been in his movies. Know. The word that you 0:00:17.720 --> 0:00:21.040 made up that I really like is the word engineeringly. 0:00:21.600 --> 0:00:24.000 That was pretty a pretty good word. But how do 0:00:24.040 --> 0:00:26.279 you use it in a sentence. Let's say you could say, 0:00:26.320 --> 0:00:32.600 for example, a warp drive is physically possible, but engineeringly impossible. 0:00:32.760 --> 0:00:34.760 That just sounds to me like you need better engineers. 0:00:35.440 --> 0:00:38.400 We definitely need better engineers, and I hope that they're 0:00:38.440 --> 0:00:41.800 out there in our audience listening today because we have 0:00:42.000 --> 0:01:02.200 some engineeringly very challenging projects on the docket. Ye hi, 0:01:02.240 --> 0:01:05.720 am orhammy cartoonists and the creator of PhD comments, Hi, 0:01:05.959 --> 0:01:08.840 I'm Daniel. I'm a particle physicist, and I'm happy to 0:01:08.840 --> 0:01:12.560 put off my problems onto engineers, even your personal problems. 0:01:12.600 --> 0:01:15.200 There does seem to be a proliferation of engineers. You know, 0:01:15.280 --> 0:01:19.080 back in the day that was mechanical electric. You make 0:01:19.120 --> 0:01:21.800 it sound like we're a pest or, but you know, 0:01:21.840 --> 0:01:25.880 now you've got the software engineers, you've got social engineers, 0:01:25.959 --> 0:01:28.320 You've got every kind of engineer. It's crazy. So yeah, 0:01:28.360 --> 0:01:32.600 maybe Daniel's personal problem engineers, I supposed to physicists who 0:01:32.640 --> 0:01:36.400 there's only one kind. There are only a few of us. Yeah, 0:01:36.400 --> 0:01:40.800 that's true. There's like solid state matter, wet matter, dark matter. 0:01:41.040 --> 0:01:42.920 It's been a while since we invented a new kind 0:01:42.920 --> 0:01:46.240 of physicist. Yah, maybe it's time. Maybe it's time. Yeah, 0:01:46.360 --> 0:01:50.080 Daniel's personal problem physicists. I don't think any of my 0:01:50.120 --> 0:01:53.800 personal problems can be solved with physics. That there's learnal 0:01:53.920 --> 0:01:57.120 laws there to be found. But welcome to our podcast. 0:01:57.200 --> 0:02:00.560 Daniel and Jorge explained the Universe State production of Hard Radio, 0:02:01.160 --> 0:02:04.160 in which we focus on the questions that can be answered, 0:02:04.240 --> 0:02:07.360 the questions that might one day in the future be answered, 0:02:07.640 --> 0:02:10.880 questions about how the world works, about what the universe 0:02:10.960 --> 0:02:12.959 is like, how it will end, and how it is 0:02:13.000 --> 0:02:17.200 put together on the smallest scale. Yeah, we love questions, 0:02:17.200 --> 0:02:19.600 and we love questions for which we know the answers 0:02:19.680 --> 0:02:21.880 and we know the question. We love the also questions 0:02:21.880 --> 0:02:24.040 for which we don't know the answers, because there are 0:02:24.040 --> 0:02:27.320 still a lot of questions out there in the universe 0:02:27.400 --> 0:02:30.440 that nobody knows the answer to, and often on this 0:02:30.560 --> 0:02:33.080 podcast we take a tour of some of those questions. 0:02:33.160 --> 0:02:36.080 We show you what's in the mind of scientists at 0:02:36.160 --> 0:02:38.960 the forefront of knowledge is they try to peel back 0:02:39.000 --> 0:02:42.320 a layer of reality and expose the universe as it 0:02:42.400 --> 0:02:45.160 really is. And sometimes we take you on a tour 0:02:45.200 --> 0:02:48.560 of the minds of our listeners, thinking about what everybody 0:02:48.560 --> 0:02:51.239 out there is wondering about. Yeah, and we love taking 0:02:51.320 --> 0:02:54.280 lists questions from listeners because they really sort of give 0:02:54.360 --> 0:02:57.200 us an insight into what people are thinking and what 0:02:57.360 --> 0:03:00.680 they're what our podcast is kind of make them think about. 0:03:00.840 --> 0:03:02.760 That's right, and not just because they give us sort 0:03:02.800 --> 0:03:06.119 of like a checkpoint so that we understand what listeners 0:03:06.120 --> 0:03:09.240 are getting and what they're confused about. But sometimes listeners 0:03:09.320 --> 0:03:12.919 questions really put their finger on something amazing about the universe. 0:03:13.240 --> 0:03:16.760 When I teach, you know, freshman physics here you see Irvine, 0:03:16.960 --> 0:03:19.080 it's when they ask a question that it makes me 0:03:19.120 --> 0:03:21.040 think about a topic in a new way, makes me 0:03:21.120 --> 0:03:24.079 explain in a new way, and then it really makes 0:03:24.120 --> 0:03:27.160 me understand it. So listener questions are really a source 0:03:27.200 --> 0:03:29.400 of insight. Yeah, And let's face it, we have I 0:03:29.440 --> 0:03:35.080 think the best listeners in the universe Daniel Podcast on Earth, 0:03:35.200 --> 0:03:37.760 and I would say in anywhere else in the universe, 0:03:37.800 --> 0:03:40.400 I think we have the best listeners. That's right, And 0:03:40.440 --> 0:03:43.200 we're talking specifically about you. You know who you are. 0:03:43.600 --> 0:03:45.920 We're talking about you right there listening to us right now. 0:03:46.320 --> 0:03:49.360 You're the best. You're our favorite listen. You're the best looking, 0:03:49.600 --> 0:03:53.040 you smell great today, and you ask awesome questions and 0:03:53.160 --> 0:03:54.960 tell my kids that all the time. I'm like, you're 0:03:55.000 --> 0:03:58.080 my favorite daughter, and she's like, I'm your only daughter 0:03:58.560 --> 0:04:05.480 that I know of. Daniel and Jorge dig Into or 0:04:05.560 --> 0:04:07.960 his sort of past. Hey, you know, if this is 0:04:07.960 --> 0:04:10.280 going to be Daniel and Jorge starting to tell a novella, 0:04:10.360 --> 0:04:12.000 then you're going to have some sort of you know, 0:04:12.040 --> 0:04:14.200 other family show up at some point in season seven. 0:04:14.240 --> 0:04:20.680 My evil twin twins genetically the same. Does that mean 0:04:20.720 --> 0:04:24.359 their kids are sort of also like your kids? Boy? Interesting, 0:04:24.400 --> 0:04:26.720 he's had a great listener question. Yeah, Or does that 0:04:26.800 --> 0:04:28.760 mean if you can have, if you can be twins 0:04:28.800 --> 0:04:30.440 and one of you is evil, does that mean that 0:04:30.480 --> 0:04:33.120 evil is not genetic? Or maybe you are evil but 0:04:33.160 --> 0:04:36.919 you do you don't know it. There are no good twins, 0:04:36.960 --> 0:04:40.040 is that what you're saying? Well, they should either both 0:04:40.040 --> 0:04:42.560 be good or both be evil. I'm sure that all 0:04:42.600 --> 0:04:45.560 the twins listening right now are both good? Well, anyways, 0:04:45.760 --> 0:04:47.520 we do have the best listeners and they do ask 0:04:47.520 --> 0:04:50.760 the best questions that they send us through Twitter or 0:04:50.880 --> 0:04:54.720 Facebook or Instagram or by email. And if you're out 0:04:54.720 --> 0:04:56.560 there listening to this podcast and you have a question 0:04:56.600 --> 0:04:58.960 about the universe, you can also write it to us 0:04:59.000 --> 0:05:02.400 and we will eventually get to it on the podcast. 0:05:02.960 --> 0:05:05.600 That's right, And we answer all of our listener emails 0:05:05.640 --> 0:05:09.360 pretty promptly. Sometimes people writing asking a good physics questions. 0:05:09.440 --> 0:05:13.719 Sometimes people writing asking sort of off the wall questions. Uh, 0:05:13.760 --> 0:05:16.960 nobody so far is asking for marriage advice. But here's 0:05:16.960 --> 0:05:19.039 a question we got last week which sort of made 0:05:19.080 --> 0:05:22.440 me chuckle. It's from Gridget saying and here's what he 0:05:22.480 --> 0:05:25.279 had to say. He wrote, if we assume the world 0:05:25.360 --> 0:05:28.760 is a simulation, do you think there's only one conscious 0:05:28.800 --> 0:05:31.880 being and the rest of the world are just biological zombies? 0:05:32.040 --> 0:05:36.960 Or everyone is conscious? I love this question. It's like 0:05:37.200 --> 0:05:39.440 am I playing a video game? Or are we all 0:05:39.440 --> 0:05:41.719 playing a video game together? It's like are you a 0:05:41.760 --> 0:05:46.960 non player? Yeah? Yeah? Or is there somebody really in there? Interesting? Well, 0:05:47.000 --> 0:05:49.160 it just gets to the bottom of consciousness, right, like 0:05:49.800 --> 0:05:54.239 kind of machine be conscious, kind of machine be conscious. Yeah, 0:05:54.320 --> 0:05:56.000 and maybe this guy spends a lot of time in 0:05:56.120 --> 0:05:59.280 video games wondering if those other players are real or not. 0:05:59.680 --> 0:06:02.080 But a fun question, but not one that I, you know, 0:06:02.240 --> 0:06:06.479 necessarily have any expertise or ability to answer. So I 0:06:06.520 --> 0:06:09.600 could pontificate as a physicist, but I think the physicists 0:06:09.640 --> 0:06:12.719 spend too much time talking about things outside their area 0:06:12.720 --> 0:06:15.280 of expertise. So I'm gonna have to point on that one. 0:06:17.200 --> 0:06:19.839 Maybe you've noticed that what if? What if you're playing 0:06:19.839 --> 0:06:22.000 a bit of games where you have to kill zombies, 0:06:22.320 --> 0:06:25.880 then technically are those zombies? But are those zombies conscious? 0:06:25.960 --> 0:06:28.560 But they can't because there's zombies? Yeah, well you could 0:06:28.560 --> 0:06:32.640 be committing digital moral crimes. But we love answering listener 0:06:32.720 --> 0:06:35.280 questions and sometimes we have episodes where we ask to them, 0:06:35.279 --> 0:06:37.719 and so today is what are those episodes? So today 0:06:37.720 --> 0:06:46.680 on the program, we'll be tackling listener questions about the universe. 0:06:46.960 --> 0:06:49.680 That's right. We'll be touching on exotic matter, will be 0:06:49.720 --> 0:06:52.640 building roads that span the Earth, and we'll take our 0:06:52.680 --> 0:06:56.200 minds to other galaxies and wondering what life is like 0:06:56.400 --> 0:07:00.720 out there aliens. Basically, we're feel I feel like we 0:07:00.760 --> 0:07:04.960 can have a listener questions episode without touching the hitting 0:07:04.960 --> 0:07:07.440 the alien button. Are you saying that's because our listeners 0:07:07.480 --> 0:07:10.160 are fascinated with aliens? Are you suspecting that I'm picking 0:07:10.200 --> 0:07:13.720 the alien questions out of the slush pile. I feel 0:07:13.800 --> 0:07:18.880 like there's a Van diagram there listener questions and things 0:07:19.000 --> 0:07:21.520 Daniel loves to talk about. If you have a question 0:07:21.520 --> 0:07:24.520 about anything, dear listeners, just put the word alien in 0:07:24.520 --> 0:07:27.480 it and it will increase your chances that we'll talk 0:07:27.520 --> 0:07:30.840 about it. That's fair, that's good advice. Yea, I have 0:07:30.880 --> 0:07:33.080 a question about dark matter. Just wonder if dark about 0:07:33.080 --> 0:07:36.160 her could be made by aliens? And well, I'm sure 0:07:36.160 --> 0:07:38.880 we'll consider it. My kids know that already. They're like, hey, Dad, 0:07:38.920 --> 0:07:41.440 can I have ten bucks? It's for aliens? Yeah, sure, 0:07:41.480 --> 0:07:43.200 here we go. All right, So today we have three 0:07:43.280 --> 0:07:46.280 questions from listeners from all around the world, and so 0:07:46.360 --> 0:07:48.840 we'll be tackling each of these questions one by one. 0:07:49.560 --> 0:07:52.560 And so the first question comes from Maria from Canada 0:07:52.840 --> 0:07:57.480 and she has a question about exotic matter. Here's your question. Hi, 0:07:57.560 --> 0:07:59.680 Daniel and Jorgey. My name is Maria and I'm a 0:07:59.720 --> 0:08:04.440 listen from Victoria, Canada and I was wondering what's exotic matter, 0:08:05.000 --> 0:08:08.000 how is it different from dark matter or antimatter? And 0:08:08.160 --> 0:08:10.600 how many different kinds of matter even are there? Anyways, 0:08:10.760 --> 0:08:13.600 thank you so much, awesome questions. I feel like she's 0:08:13.600 --> 0:08:17.440 sort of get throwing little shaded physicists. I felt that, 0:08:17.520 --> 0:08:20.240 I felt that shade, like, hey, get this under control, 0:08:20.320 --> 0:08:24.560 Like people are ridiculous, Yeah, that this matter naming is 0:08:24.600 --> 0:08:27.120 getting out of control. It's we have as many kinds 0:08:27.160 --> 0:08:29.400 of matter as there are like fields of engineering, and 0:08:29.400 --> 0:08:31.680 that's absurd. We we need a new feel for every 0:08:31.720 --> 0:08:33.600 kind of matter you guys come up with. So it's 0:08:33.600 --> 0:08:38.280 not our fault. We need exotic physics and exotic physicists. 0:08:38.360 --> 0:08:40.800 We're just trying to plug the holes of physicist are creedive. 0:08:41.480 --> 0:08:43.920 Thank you, by the way for your tireless work plugging 0:08:43.920 --> 0:08:45.520 our holes. We just need to have a lot of 0:08:45.600 --> 0:08:50.839 kinds of matter in our universe. There's, for example, baryonic matter, antimatter, 0:08:51.000 --> 0:08:55.360 dark matter, exotic matter, supersymmetric matter. Yeah. Yeah, the list 0:08:55.400 --> 0:08:58.880 goes on. And this is a totally great question, and 0:08:59.040 --> 0:09:01.880 it's a fair question also because this term is used 0:09:01.920 --> 0:09:04.760 in lots of different ways. In a very general way, 0:09:04.840 --> 0:09:07.760 people use the phrase exotic matter to me literally, just 0:09:07.840 --> 0:09:10.760 that like matter that seems kind of weird, like exotic, 0:09:11.120 --> 0:09:14.600 something different from the every day you know, the everyday 0:09:14.640 --> 0:09:18.480 matter is made of quarks and electrons, and so from 0:09:18.520 --> 0:09:22.080 that definition, exotic matter could be like dark matter, you know, 0:09:22.280 --> 0:09:25.760 or other weird stuff that's out there. Oh boy, now 0:09:25.760 --> 0:09:28.440 you're just making it worse, Daniel. Now you're like overlapping 0:09:28.480 --> 0:09:31.680 all these matter designations. We're not great at that. In 0:09:31.720 --> 0:09:34.440 particle physics, you know, matter could just be any matter 0:09:34.559 --> 0:09:36.880 that is against something. Yeah, it could be. So it's 0:09:37.040 --> 0:09:39.400 it's a different opinion. It's a very vague tournament. And 0:09:39.440 --> 0:09:43.760 it could even be weird forms of familiar matter. Like 0:09:44.120 --> 0:09:46.640 if you take atoms and you cool them down and 0:09:46.720 --> 0:09:50.480 make weird quantum states like Bose Einstein condensates, some people 0:09:50.480 --> 0:09:54.120 would call that exotic matter. Or if you make super fluids, 0:09:54.280 --> 0:09:56.880 you could call that exotic matter. Well, well, let's take 0:09:56.880 --> 0:09:59.480 it's a step back here. You're saying that the word 0:09:59.480 --> 0:10:03.640 exotic matter is not well defined in physics. Yeah, if 0:10:03.640 --> 0:10:06.720 you just google what is exotic matter? For example, you 0:10:06.760 --> 0:10:09.920 will see articles physicists discover exotic matter, but then it 0:10:09.920 --> 0:10:13.120 turns out it's actually about super fluids, or physicists use 0:10:13.200 --> 0:10:16.640 exotic matter to communicate quantum mechanically and then it turns 0:10:16.640 --> 0:10:19.880 out it's just bosion stain content. States m hmmm. So 0:10:19.960 --> 0:10:23.079 you're saying, just like in our culture, the word exotic 0:10:23.200 --> 0:10:26.800 is sort of outdated and inappropriate. Yeah, it's a little bit. 0:10:27.160 --> 0:10:30.600 It's been a bit abused. But there is also sort 0:10:30.640 --> 0:10:33.160 of a narrower version of exotic matter that has a 0:10:33.240 --> 0:10:36.800 very specific, fascinating meeting in particle physics that I think 0:10:36.800 --> 0:10:39.600 we could dig into. Oh I see, all right, So 0:10:39.679 --> 0:10:43.280 in general, it can just mean any kind of non 0:10:43.280 --> 0:10:48.040 normal matter, weird, spooky Halloween matter in the loose sort 0:10:48.080 --> 0:10:52.360 of definition of yes, spooky Halloween matter, or you know 0:10:52.480 --> 0:10:59.880 matter from the Orient, which is that racist. Yeah yeah, yeah, 0:11:00.000 --> 0:11:04.280 extern centric and but um no, you're saying, and in 0:11:04.440 --> 0:11:08.160 general sense it just means weird matter. But there's also 0:11:08.200 --> 0:11:11.200 sort of maybe a hardcore group of physicists who are like, hey, 0:11:11.280 --> 0:11:14.040 this means something very specific. Yeah, they rock out the 0:11:14.080 --> 0:11:15.959 heavy metal and they talk about this kind of matter. 0:11:16.320 --> 0:11:20.640 They are hardcore, and that's matter with negative mass. So 0:11:20.720 --> 0:11:24.560 in particle physics we talk about exotic particles or exotic 0:11:24.600 --> 0:11:28.600 matter and what we mean are particles that have negative mass, 0:11:28.600 --> 0:11:31.520 Like you know that mass is something we attached to particles, 0:11:31.520 --> 0:11:33.880 and I have mass and you have mass, And a 0:11:33.960 --> 0:11:36.760 fascinating thing about mass is that it seems to always 0:11:36.800 --> 0:11:40.360 be positive. So we've invented this idea. Maybe there are 0:11:40.360 --> 0:11:42.559 particles out there with the other kind of mass and 0:11:42.760 --> 0:11:46.120 negative kind of mass. Mm hmmm, because right, because mass 0:11:46.200 --> 0:11:48.400 is just kind of a label, right, it's not actually 0:11:48.440 --> 0:11:51.400 like stuff. It's just kind of a like an electric 0:11:51.440 --> 0:11:54.400 charge can be positive or negative. Yeah, we don't really 0:11:54.480 --> 0:11:57.079 understand it. And if you zoom down to an individual particle, 0:11:57.600 --> 0:12:01.319 particles have no volume. They're just points and base with labels, right, 0:12:01.400 --> 0:12:04.480 like electric charges, you said, And mass is another property, 0:12:04.920 --> 0:12:07.440 and mass is a property that these particles get from 0:12:07.559 --> 0:12:10.560 interaction with the Higgs field. But the fascinating thing about 0:12:10.559 --> 0:12:12.560 mass is that it always seems to be positive. Right. 0:12:12.640 --> 0:12:14.920 We measure the mass of all of these particles and 0:12:15.000 --> 0:12:17.480 we see that they have positive mass, and that has 0:12:17.480 --> 0:12:22.360 fascinating consequences because the Higgs field always gives these particles 0:12:22.360 --> 0:12:25.440 positive mass, or like the interaction is always positive, like 0:12:25.440 --> 0:12:27.679 I has anyone had a bad experience with the Higgs field? 0:12:27.720 --> 0:12:31.680 I guess it only has five star reviews on Yelp. 0:12:31.760 --> 0:12:37.720 So yeah, in the Higgs field widely loved, would recommend yes, 0:12:37.880 --> 0:12:40.440 Higgs field good. Um, But did you know what I mean? Like, 0:12:40.720 --> 0:12:42.960 if something has negative masses, that mean that when it 0:12:43.000 --> 0:12:45.440 interacts with the Higgs field it gets the negative mass 0:12:45.600 --> 0:12:47.400 or what does that mean? Well, if a particle had 0:12:47.480 --> 0:12:50.120 negative mass, we don't know how it would get that mass. 0:12:50.160 --> 0:12:52.000 One way to get mass is to interact with the 0:12:52.080 --> 0:12:54.360 Higgs field. We think there might be other ways for 0:12:54.440 --> 0:12:57.160 particles to get mass too, but we've never seen one 0:12:57.240 --> 0:13:00.360 like that, So there could be various ways for articles 0:13:00.360 --> 0:13:02.719 to get mass. It doesn't just have to be the 0:13:02.840 --> 0:13:05.000 Higgs field. The Higgs field just kind of determs how 0:13:05.000 --> 0:13:08.120 it moves in the universe. Right, But you can still 0:13:08.400 --> 0:13:11.360 have mass independent of the Higgs field. Yes, you can 0:13:11.440 --> 0:13:13.640 get mass without getting it from the Higgs field. We 0:13:13.640 --> 0:13:16.319 haven't ever done that, but like, we don't know neutrinos, 0:13:16.559 --> 0:13:18.640 do they get mass from the Higgs field or not? 0:13:18.880 --> 0:13:20.760 Do they get mass in this other weird way And 0:13:20.800 --> 0:13:22.679 we can dive into that and a whole other podcast, 0:13:23.000 --> 0:13:25.120 But I think the important concept to remember is what 0:13:25.200 --> 0:13:27.000 you just said is that it changes how you move 0:13:27.120 --> 0:13:29.720 through the universe. Often, when we talk about mass, we 0:13:29.760 --> 0:13:33.560 really mean two different things. One is inertia, like you 0:13:33.640 --> 0:13:36.559 give something a push. It takes a push to move something, 0:13:36.600 --> 0:13:39.720 to change something's momentum, to get it started, takes a push. 0:13:40.040 --> 0:13:43.160 We call that inertia. Really, that's mass, right, and that 0:13:43.200 --> 0:13:46.840 comes from the formula F equals M. A force is 0:13:46.920 --> 0:13:50.200 mass times acceleration. To accelerate something, you have to apply 0:13:50.320 --> 0:13:53.520 a force, and the mass is the relationship between those two. 0:13:53.840 --> 0:13:56.719 So that's mass. Concept Number one is inertial methods. How 0:13:56.720 --> 0:13:59.400 hard it is to push? Yeah, how hard is it 0:13:59.440 --> 0:14:01.720 to push to get it going? And also how hard 0:14:01.760 --> 0:14:04.080 is it to slow it down? Like a semi truck 0:14:04.120 --> 0:14:06.480 has a huge amount of mass, takes a huge force 0:14:06.520 --> 0:14:09.360 to slow it down. Can something have negative inertial mass? 0:14:09.480 --> 0:14:12.120 Is that possible where you like, you push it and 0:14:12.160 --> 0:14:16.160 it goes faster, or you know, like it pushed you 0:14:16.200 --> 0:14:17.800 push it and it actually pulls you or something, and 0:14:18.040 --> 0:14:19.680 you know what, that's what would happen if you gave 0:14:19.720 --> 0:14:22.480 it a push to the left and it had negative 0:14:22.480 --> 0:14:24.720 inertial mass, it would move to the right, it would 0:14:24.760 --> 0:14:27.280 push you, push you back. Yeah, so the force would 0:14:27.320 --> 0:14:30.480 be the opposite direction of the acceleration. So the weird 0:14:30.560 --> 0:14:33.000 thing about negative mass is like, it seems weird. It's 0:14:33.040 --> 0:14:37.280 totally counterintuitive, but mathematically it kind of hangs together, like 0:14:37.320 --> 0:14:40.080 we don't have a reason to believe it doesn't exist. 0:14:40.120 --> 0:14:42.640 You could fit it into all of our equations. We've 0:14:42.680 --> 0:14:45.040 just never seen an example of it. That kind of 0:14:45.040 --> 0:14:47.880 weird example could happen where you like push it one 0:14:47.880 --> 0:14:50.520 way with the with the force field or something, but 0:14:50.560 --> 0:14:53.080 it goes the other way. Yeah, you could do that 0:14:53.400 --> 0:14:56.000 in theory. It's possible. We've never seen it, but you 0:14:56.080 --> 0:14:59.240 can work out all the equations of motion and it works. 0:14:59.600 --> 0:15:02.160 So you push into the left and it moves to 0:15:02.200 --> 0:15:05.440 the right. But that's only one way of thinking about mass. 0:15:05.520 --> 0:15:09.200 Is a whole second concept of mass, which is mass 0:15:09.280 --> 0:15:13.320 in gravity. Like two objects that have mass feel gravity 0:15:13.320 --> 0:15:16.360 and attract each other. So so if something has negative mass, 0:15:16.360 --> 0:15:20.720 it could maybe repel another thing, would mass. Yeah, the 0:15:20.720 --> 0:15:24.080 fascinating thing about positive mass and gravity is that gravity 0:15:24.200 --> 0:15:26.400 is one of the only forces that so far seems 0:15:26.440 --> 0:15:29.200 to be just attractive. Right, you get pulled in by 0:15:29.240 --> 0:15:31.440 the sun, you get pulled in by the moon. There's 0:15:31.480 --> 0:15:35.440 no way, you get pushed by gravity, whereas like electromagnetism, 0:15:35.480 --> 0:15:37.840 there's a positive and negativity, and if you have the 0:15:37.920 --> 0:15:41.480 same charges you get repelled and gravity it is only 0:15:41.520 --> 0:15:45.480 positive and it seems to only be attractive. So if 0:15:45.520 --> 0:15:49.480 you add negative mass, then yeah, you could get repulsive gravity. 0:15:49.640 --> 0:15:53.440 Or I guess maybe in like the Einstein space bending picture, 0:15:53.560 --> 0:15:56.120 it would be sort of bend space the other way. Yeah, 0:15:56.280 --> 0:16:00.040 instead of having like a dent down into space, it 0:16:00.040 --> 0:16:02.560 would be like a like an explosion of space a 0:16:02.560 --> 0:16:04.880 little bit. So things like slide away from you like 0:16:04.920 --> 0:16:09.000 a z in space, like a like a bump a space. 0:16:10.760 --> 0:16:14.000 Don't pop at ZiT. That's like a gravity bomb. Yeah, 0:16:14.120 --> 0:16:17.480 you have a negative experience. Don't do it. It's weird though, 0:16:17.520 --> 0:16:20.640 because this is a little counterintuitive. You know that positive 0:16:20.680 --> 0:16:24.440 mass of course attracts other positive mass. It would also 0:16:24.480 --> 0:16:29.360 attract negative mass, and negative mass would repel negative mass 0:16:29.440 --> 0:16:32.800 and also positive masses. Wait what, it wouldn't be like 0:16:32.880 --> 0:16:36.760 electrical charges. It's not like electrical charges because you just 0:16:36.840 --> 0:16:39.680 said that. We don't think of gravity as a force. 0:16:39.720 --> 0:16:42.880 We think as a bending of space. So positive mass 0:16:42.920 --> 0:16:45.160 makes like a dent in space like a whole in 0:16:45.200 --> 0:16:48.120 space for things to fall into regardless of their mass, 0:16:48.280 --> 0:16:51.720 and negative masses make space zits. That was actually Einstein's term, 0:16:52.360 --> 0:16:59.520 and is it z it's their spation and now that's 0:16:59.520 --> 0:17:02.160 a joke. But a negative mass make these would make 0:17:02.160 --> 0:17:04.480 these like you know, or I'm gonna say zits in 0:17:04.520 --> 0:17:11.720 space because regardless of the mass of the other thing. Right, So, 0:17:11.880 --> 0:17:16.840 positive masses attract other positive or negative masses, and negative 0:17:16.840 --> 0:17:20.879 masses repel negative or positive masses. It's like the opposite 0:17:20.960 --> 0:17:24.760 of a black hole. Yeah, and it's weirdly sort of asymmetric, right. 0:17:24.800 --> 0:17:26.960 You like to think about the forces as being symmetric, 0:17:27.160 --> 0:17:29.760 so like it depends on the product of the charges 0:17:29.880 --> 0:17:32.439 or something, but it wouldn't be. And that means if 0:17:32.480 --> 0:17:34.960 you have like a positive mass and a negative mass 0:17:35.040 --> 0:17:38.760 next to each other, then the positive masses pulling on 0:17:38.800 --> 0:17:41.879 the negative mass, but the negative mass is pushing on 0:17:41.920 --> 0:17:45.520 the positive mass. Um what would happen? They would actually 0:17:45.600 --> 0:17:48.880 just like lead to this runaway motion because the positive 0:17:48.880 --> 0:17:52.239 masses pulling on the negative the negative is trying to 0:17:52.240 --> 0:17:56.439 repel the positive. Attraction of the negative actually pushes the 0:17:56.520 --> 0:17:59.840 other direction, right because of negative and inertial mass, And 0:18:00.000 --> 0:18:02.480 it would just skip out of town. Let's skip out 0:18:02.480 --> 0:18:07.720 of town for real. Well, we don't know, Like this 0:18:07.800 --> 0:18:10.680 is the idea, so we've never seen this stuff. It's 0:18:10.720 --> 0:18:12.199 just sort of an idea, and and it would be 0:18:12.200 --> 0:18:15.600 pretty helpful because if we did have exotic mass, we 0:18:15.640 --> 0:18:19.000 could use it to, for example, stabilize wormholes and travel 0:18:19.040 --> 0:18:21.240 through the galaxy and this kind of stuff. But we've 0:18:21.280 --> 0:18:24.040 never seen any of it. It's just sort of like, yeah, 0:18:24.040 --> 0:18:26.000 I guess that's in the lad. The next question, which 0:18:26.040 --> 0:18:28.719 is is this even real or is it just theoretical. 0:18:29.280 --> 0:18:32.440 It's just theoretical, but it's important to recognize these sort 0:18:32.440 --> 0:18:35.920 of theoretical opportunities. Some of these other kinds of matter 0:18:36.000 --> 0:18:39.040 we talked about, like antimatter. They started out it's theoretical, 0:18:39.080 --> 0:18:42.520 and somebody noticed, hey, the equations also work if you 0:18:42.680 --> 0:18:45.000 flip all these signs and make this other weird kind 0:18:45.040 --> 0:18:47.160 of matter. So maybe that's real, and it turns out 0:18:47.280 --> 0:18:51.400 it's true. So seeing these mathematical symmetries are often guides 0:18:51.640 --> 0:18:54.480 actually binding stuff in reality, and that will tell us 0:18:54.520 --> 0:18:58.040 more about the universe. Yeah, but the universe is asymmetric sometimes, 0:18:58.119 --> 0:19:01.280 like there's a lot of matter out there, very very 0:19:01.280 --> 0:19:04.200 little antimatter, if any. We don't know why that is. 0:19:04.680 --> 0:19:07.639 So there's a lot of positive matter out there, none 0:19:07.800 --> 0:19:11.000 or maybe very little negative matter. Why is that right? 0:19:11.359 --> 0:19:15.720 Fascinating questions? Yeah, maybe not all the matter matters. All 0:19:15.760 --> 0:19:18.520 matter matters, man, but all right, so, um, it seems 0:19:18.560 --> 0:19:22.639 like to answer Maria's question, exotic matter. Um can mean 0:19:22.680 --> 0:19:25.720 a lot of things, but it generally it's terribly used 0:19:25.760 --> 0:19:28.760 just to me, like not normal matter, meaning the matter 0:19:28.840 --> 0:19:30.919 you and I are made out of. It's kind of 0:19:30.960 --> 0:19:34.760 weird or unusual. Some physicists call that exotic matter. But 0:19:35.119 --> 0:19:38.080 there's also sort of the hardcore definition, which is that 0:19:38.200 --> 0:19:42.480 it means matter with negative mass, which is theoretically fascinating, 0:19:42.760 --> 0:19:45.639 totally possible, but never been seen. But you know, she 0:19:45.720 --> 0:19:48.200 also asked another question, which is how many different kinds 0:19:48.240 --> 0:19:52.080 of matter are there? Anyway? And that's such a good question. 0:19:52.160 --> 0:19:55.560 It's a question that I have also because we see 0:19:55.600 --> 0:19:58.000 these symmetries in nature. We see like, oh, there's matter 0:19:58.160 --> 0:20:02.240 and antimatter, there's maybe positive matter and negative mass matter, 0:20:02.520 --> 0:20:05.760 and there's other symmetries like we talked about supersymmetry on 0:20:05.760 --> 0:20:09.119 this program, like maybe every spin half particle has a 0:20:09.200 --> 0:20:12.720 spin one particle that that balances it, and vice versa, 0:20:13.240 --> 0:20:16.520 and all these symmetries tell us something deep about the universe, 0:20:16.560 --> 0:20:19.640 about the way it's put together, about what it reflects 0:20:19.640 --> 0:20:21.680 that its deepest level, And we don't know what the 0:20:21.720 --> 0:20:24.320 answers are. But every time we find a symmetry, I 0:20:24.359 --> 0:20:27.240 feel like it's revealed something about the universe that we've 0:20:27.240 --> 0:20:29.639 been desperate to find out. Every time you find a 0:20:29.640 --> 0:20:32.000 new kind of matter or think up but you kind 0:20:32.040 --> 0:20:35.399 of matter, it kind of pushes your definition of what 0:20:35.520 --> 0:20:38.760 can exist. Yeah, and these symmetries are really important. You know. 0:20:38.840 --> 0:20:41.520 We talked also on this program about how the universe 0:20:41.680 --> 0:20:45.000 is left handed. It prefers particles that spin in a 0:20:45.080 --> 0:20:47.680 certain way relative to their motion. We don't know why 0:20:47.720 --> 0:20:50.240 that is, and so people suggested and maybe there's another 0:20:50.320 --> 0:20:53.919 kind of matter called mirror matter, where it's the opposite. 0:20:54.359 --> 0:20:56.840 And every time you have these symmetries, you have to ask, 0:20:56.880 --> 0:20:58.480 why is it this way and not the other way? 0:20:58.480 --> 0:21:01.560 Why is the universe sort of by furcated into two options. 0:21:01.560 --> 0:21:04.200 What does that mean about the nature of the universe 0:21:04.560 --> 0:21:07.040 At some higher temperature earlier in the universe, was this 0:21:07.119 --> 0:21:09.880 all unified into something beautiful? And crystalline, and then it's 0:21:09.880 --> 0:21:12.479 just sort of cracked and fell apart. We don't know. 0:21:12.680 --> 0:21:15.879 I think my favorite kind of matter are the matters 0:21:15.920 --> 0:21:19.399 of the heart. Daniel. All right, well, we hope that 0:21:19.480 --> 0:21:22.439 answered your question, Maria, thanks so much for asking the question. 0:21:22.520 --> 0:21:24.800 And so let's get into our two other questions for 0:21:24.840 --> 0:21:28.080 the episode, and these are about the biggest road ever 0:21:28.119 --> 0:21:33.240 built and also about intergalactic aliens. But first let's take 0:21:33.240 --> 0:21:49.200 a quick break. Alright, we're answering listener questions today. Answer 0:21:49.240 --> 0:21:52.639 Our next question comes from Rahul from India, and so 0:21:52.680 --> 0:21:55.880 he has a question about an interesting idea for an 0:21:55.960 --> 0:22:00.040 infinite road. Here is so, imagine you start building a 0:22:00.040 --> 0:22:03.160 bridge or a highway above the surface, and it goes 0:22:03.280 --> 0:22:05.600