WEBVTT - What Are Quantum Fields? 0:00:06.600 --> 0:00:08.879 Hey, Daniel, you know how in science fictions are all 0:00:09.039 --> 0:00:13.239 kinds of fields. You mean like big expansive lawns. No, 0:00:13.320 --> 0:00:17.480 I mean like force fields or energy fields. Oh my god, 0:00:17.520 --> 0:00:21.040 you know none of that is real, right? What the 0:00:21.079 --> 0:00:25.000 force from Star Wars is not real? None of it. Absolutely, 0:00:25.120 --> 0:00:27.480 none of that is real. Wait? Wait, what about like 0:00:27.760 --> 0:00:31.000 energy fields? Those are real? Right? Energy fields are not real. 0:00:31.640 --> 0:00:35.800 But there's something that's even weird or even cooler that 0:00:36.040 --> 0:00:39.280 is real. Wait, cooler than star wars. Cooler than star 0:00:39.280 --> 0:00:43.120 Wars are quantum fields. And that's a thing that is 0:00:43.159 --> 0:00:46.360 real and is everywhere in the universe. I don't believe it. 0:00:46.400 --> 0:00:48.919 I think you just made it up. We physicists did, 0:00:48.960 --> 0:00:51.560 in fact, invent quantum fields. But it turns out because 0:00:51.560 --> 0:00:54.200 it accurately predicts what happens in the universe, it might 0:00:54.280 --> 0:00:56.520 just be real. Is that like field of dream Like 0:00:56.560 --> 0:00:59.000 if you think of it, people will believe it. That's right, 0:00:59.120 --> 0:01:02.480 quantum fields of quantum dreams. That's basically what being a 0:01:02.480 --> 0:01:05.640 physicist is all about, having quantum dreams. And you're the 0:01:05.720 --> 0:01:27.039 Kevin Costner in the situation him and I'm Daniel, and 0:01:27.080 --> 0:01:30.200 welcome to our podcast. Daniel and Jorge explain the universe. 0:01:30.560 --> 0:01:33.759 This is Daniel and Jorge. This is the podcast you're 0:01:33.800 --> 0:01:39.240 looking for exactly um. Yeah. On this podcast, we try 0:01:39.280 --> 0:01:41.520 to talk to you about everything in the universe. Things 0:01:41.520 --> 0:01:43.520 that are big, things that are small, things that are 0:01:43.560 --> 0:01:48.560 invisible but fill the entire universe, things that are everywhere, 0:01:48.720 --> 0:01:52.960 things you had no idea existed, but determine everything about 0:01:52.960 --> 0:01:55.600 your existence that's right. Today on the podcast, we'll talk 0:01:55.640 --> 0:02:04.360 about quantum fields. What are they? Where are they? Who 0:02:04.360 --> 0:02:07.600 are they? What are they good for? Absolutely nothing? Say 0:02:07.600 --> 0:02:10.040 it again. Is it's just a family whose last name 0:02:10.120 --> 0:02:15.959 is field, or it's a bunch of discrete playing fields 0:02:16.000 --> 0:02:18.200 somewhere quantum fields, you're gonna have one field, you can 0:02:18.200 --> 0:02:20.280 have two fields. You can't have two and a half fields. 0:02:20.280 --> 0:02:22.640 They're quantized, but once you enter, you don't really know 0:02:22.680 --> 0:02:27.079 where you're going or where you are now. A quantum 0:02:27.120 --> 0:02:30.680 field theory is something you hear about, you might have heard. 0:02:30.760 --> 0:02:33.720 It's part of modern physics. It's a theory that people 0:02:33.880 --> 0:02:37.080 use to do calculations. It's really awesome, it's impressive. But 0:02:37.200 --> 0:02:40.079 what isn't What is a quantum field? What is the 0:02:40.080 --> 0:02:42.880 theory of quantum fields? What relationship does that have to 0:02:42.919 --> 0:02:45.240 you or the rest of your life or anything at all. Well, 0:02:45.240 --> 0:02:47.440 it's more than just a part of modern physics. It's 0:02:47.720 --> 0:02:52.280 kind of like the foundation of our theory about the universe. Right, 0:02:52.400 --> 0:02:55.000 that's right. It's kind of like the language of physics currently. 0:02:55.360 --> 0:02:58.200 You know, it's quantum field theory is to modern physics 0:02:58.200 --> 0:03:01.000 the way like English is to Shakespeare. You know. We 0:03:01.080 --> 0:03:03.200 use the tools of quantum field theory to try to 0:03:03.240 --> 0:03:05.440 talk about what's going on in the universe, and it's 0:03:05.520 --> 0:03:09.919 remarkably successful. It's incredibly successful. When you guys want to 0:03:10.000 --> 0:03:12.119 use pig latin, I thought that was the We only 0:03:12.160 --> 0:03:13.840 do that when you come by, Jorge to try to 0:03:13.840 --> 0:03:18.080 confuse you. Um. But it's like the foundation of modern physics. 0:03:18.240 --> 0:03:22.200 And it's also super duper accurate. Like you guys are 0:03:22.240 --> 0:03:27.040 pretty sure is it the right way to describe the universe? Yeah, Well, 0:03:27.040 --> 0:03:29.519 on one hand, it's super duper accurate. Like we can 0:03:29.560 --> 0:03:33.240 predict the way particles interact with fields, and we can 0:03:33.240 --> 0:03:36.080 make predictions out to lots of decimal places, and then 0:03:36.120 --> 0:03:38.480 we can go out and measure how those particles interact 0:03:38.520 --> 0:03:40.760 with the fields, and it turns out those predictions are 0:03:40.800 --> 0:03:44.720 correct to like one in millions and millions. So you know, 0:03:44.800 --> 0:03:47.360 you have, on one hand, like a theoretical calculation that 0:03:47.400 --> 0:03:50.800 you've written downs is like an idea that predicts an experiment, 0:03:50.880 --> 0:03:52.240 and then you go out and you check it with 0:03:52.320 --> 0:03:56.000 a super precise experiment and get the same answer, and uh, 0:03:56.080 --> 0:03:58.520 you know it's so accurate that you think maybe this 0:03:58.600 --> 0:04:01.000 is the true story of the universe. It's not just 0:04:01.080 --> 0:04:04.960 like human ideas. This is like revealing the source code 0:04:05.040 --> 0:04:08.640 kind of thing. So you're pretty close to saying quantum 0:04:08.640 --> 0:04:12.400 fields are true. They're they're like the truth of the universe. Yes, 0:04:12.600 --> 0:04:15.320 that's except that we also know they can't be the 0:04:15.400 --> 0:04:20.080 final answer. Oh yeah, well well we'll get into it. 0:04:20.800 --> 0:04:22.760 But I will admit I don't have a clear idea 0:04:22.800 --> 0:04:25.480 of what a quantum field is um and we were 0:04:25.520 --> 0:04:28.400 wondering how many of you out there had some ideas 0:04:28.400 --> 0:04:30.640 about what it would be. So, as usual, I walked 0:04:30.640 --> 0:04:32.320 around the u C Irvine campus and I asked a 0:04:32.360 --> 0:04:35.880 bunch of very friendly, very accommentating, very willing to answer 0:04:35.960 --> 0:04:39.480 random questions you see, Irvine undergrads, and I asked them 0:04:39.560 --> 0:04:43.479 what is quantum field theory? Here's what people had to say. 0:04:43.600 --> 0:04:45.560 I have no idea, but I have heard of before. 0:04:45.800 --> 0:04:52.719 All right, Um, it's probably really to quantum mechanics UM. 0:04:52.760 --> 0:04:56.920 I'm not sure exactly what it is, but I think 0:04:56.960 --> 0:05:00.440 it describes the different factor of fields that you use 0:05:00.480 --> 0:05:06.680 in quantum mechanics. UM. Maybe the way cell atomic particles 0:05:07.080 --> 0:05:12.560 instracted with one another cool um, similar to quantum mechanics chemistry. 0:05:12.600 --> 0:05:14.800 I don't know what it is, but I've heard of it. 0:05:14.800 --> 0:05:17.679 It's something to do with general relativity. Is it trying 0:05:17.680 --> 0:05:22.000 to marry that together with quantum theory? Are the waves 0:05:22.120 --> 0:05:29.040 involved and residents of particles? Something like that? Maybe? All right, 0:05:29.160 --> 0:05:32.440 some pretty pretty good answers. I feel like, though the 0:05:32.480 --> 0:05:36.520 word quantum just give it away, you know, asked what 0:05:36.640 --> 0:05:38.880 is the quantum Google book, you can just say, oh, 0:05:39.040 --> 0:05:41.160 I think it's related to quantum particles, right, and you 0:05:41.200 --> 0:05:43.279 would be sort of right, yeah, but that's not really 0:05:43.279 --> 0:05:47.719 an answer, right, you know. Um? And and we know 0:05:47.760 --> 0:05:49.640 one of those answers is actually not from a UC 0:05:49.680 --> 0:05:53.000 Irvine undergraduate. That's from a fellow who wrote in and 0:05:53.040 --> 0:05:56.320 said that he was disappointed with the quality of the 0:05:56.360 --> 0:05:59.719 answers that the undergrads were giving. He thought he could 0:05:59.760 --> 0:06:03.040 do better. So I said, all right, here's the next 0:06:03.120 --> 0:06:06.039 question from the next podcast. Don't do any research and 0:06:06.080 --> 0:06:09.440 record your answer. And he wrote back a very humbled 0:06:09.480 --> 0:06:11.480 email and he said, Okay, you're right. It's harder than 0:06:11.480 --> 0:06:14.159 I thought it was, but he was still willing to 0:06:14.200 --> 0:06:16.040 do it, so I thought that was totally awesome. So 0:06:16.080 --> 0:06:18.880 he sent us. He sent us his description of quantum 0:06:18.880 --> 0:06:21.640 field theory. Do you think that we think in society 0:06:21.640 --> 0:06:23.719 today we think for smarter than we are because we 0:06:23.760 --> 0:06:27.200 have Google at our fingertips. You know, I feel like 0:06:27.200 --> 0:06:29.160 you know everything because we kind of do. If we 0:06:29.360 --> 0:06:30.960 just give us a second to tap it on our phones, 0:06:31.200 --> 0:06:33.680 it's easier to access information. But sometimes that makes me 0:06:33.720 --> 0:06:36.160 feel less smart because I feel like I have less 0:06:36.200 --> 0:06:39.000 information actually in my head and I'm relying more and 0:06:39.080 --> 0:06:42.200 more on these facilities that are outside my brain. You 0:06:42.200 --> 0:06:44.919 know this, Even though the cognitive connection between me and 0:06:44.960 --> 0:06:47.440 Google keeps increasing, I don't feel like that makes me smarter. 0:06:47.560 --> 0:06:51.960 It just makes me plus Google smarter. What what about 0:06:52.000 --> 0:06:54.320 the day that you get you connect your phone through 0:06:54.320 --> 0:06:56.760 your brain or something, then you're sort of technically as 0:06:56.760 --> 0:07:02.120 smart as Google. The day that I become Google. That's 0:07:02.160 --> 0:07:05.640 the singularity, the Google's singularity. Yeah, we all connect our brains, 0:07:05.640 --> 0:07:08.520 we all become one mega consciousness. The Google were smoking 0:07:08.520 --> 0:07:10.880 over there today, Jorge, I want some pass that over. 0:07:11.800 --> 0:07:15.880 It's the googlarity, the Google larity. I look forward to that. 0:07:16.640 --> 0:07:20.000 But well, we know they're related to quantum theory, quantum 0:07:20.040 --> 0:07:23.440 field um. So let's let's let's break it down. First 0:07:23.480 --> 0:07:26.480 of all, what is a field to a physicist? Right? So, 0:07:26.800 --> 0:07:29.760 a field is just it's like a fluid that feels 0:07:29.800 --> 0:07:33.960 all of space. It's like it's something that's everywhere and 0:07:34.120 --> 0:07:36.320 everywhere in space. You have a number, right, And it 0:07:36.360 --> 0:07:39.920 comes from things like the electromagnetic field. People were puzzling 0:07:40.120 --> 0:07:42.600 a hundred years or so ago, like how do to 0:07:42.800 --> 0:07:46.040 magnets push each other apart without touching? Right? There was 0:07:46.080 --> 0:07:49.600 this action at a distance mystery like that's sort of spooky, 0:07:49.680 --> 0:07:52.920 like a yeah, right are they? How are they actually 0:07:52.920 --> 0:07:55.280 pushing each other apart? You know? And this really puzzled 0:07:55.280 --> 0:07:56.960 physicists for a while, and they came up with this 0:07:57.000 --> 0:07:59.720 idea of a field, the idea that each magnet has 0:07:59.760 --> 0:08:03.160 a magnetic field. It's this invisible thing that surrounds it, 0:08:03.480 --> 0:08:06.120 which will push on any other magnet that enters that 0:08:06.200 --> 0:08:09.840 magnetic field. Right, and the magnetic field is strongest near 0:08:09.880 --> 0:08:11.720 the source of the magnet and then it drops off 0:08:12.040 --> 0:08:14.120 just as you would expect because the magnet super far 0:08:14.120 --> 0:08:17.240 away won't feel anything. And just came because they noticed 0:08:17.320 --> 0:08:21.600 that how one magnet pulls or pushes on another sort 0:08:21.640 --> 0:08:25.160 of depends on where you put them relative to each other, right, 0:08:25.200 --> 0:08:27.400 Like where you put it around the other other one, 0:08:27.720 --> 0:08:29.840 that's right. And so they came up they said, well, wait, 0:08:29.880 --> 0:08:34.040 maybe every magnet generates in space this invisible thing. We'll 0:08:34.080 --> 0:08:36.680 call it a magnetic field, and that's the thing that 0:08:36.760 --> 0:08:40.120 does the pushing. And sort of a mystery that came 0:08:40.200 --> 0:08:43.160 up immediately was like is the field a real thing? 0:08:43.480 --> 0:08:46.160 Is it actually they're a physical thing that's that exists 0:08:46.160 --> 0:08:49.040 in the universe, Like does it have substance and can 0:08:49.080 --> 0:08:51.560 you play baseball on it? Or is it just a 0:08:51.600 --> 0:08:53.880 way that we calculate things, you know, just like a 0:08:53.960 --> 0:08:58.120 tool in our minds to help us understand things, Like 0:08:58.280 --> 0:08:59.840 is it a thing like you said, it could be 0:09:00.080 --> 0:09:02.960 like a fluid, or it could just be like a 0:09:03.000 --> 0:09:06.640 mathematical construct exactly exactly. And that's the questions people are 0:09:06.720 --> 0:09:10.760 still grappling with, right. One philosophical problem was how can 0:09:10.800 --> 0:09:12.800 things that are not touching push and pull on each other? 0:09:12.800 --> 0:09:15.200 And they answer that with okay, we just invent fields 0:09:15.400 --> 0:09:17.520 all right? Now the question is our fields a real 0:09:17.600 --> 0:09:19.920 thing or are they something else? You know, that's the 0:09:20.000 --> 0:09:22.280 joy of philosophies that every time you answer a question, 0:09:22.440 --> 0:09:25.000 it just creates another question which is just as deep. 0:09:25.880 --> 0:09:28.080 But what do you mean by a field is like 0:09:28.120 --> 0:09:30.920 a number? Because the way I learned about it in 0:09:31.280 --> 0:09:34.960 engineering is that a field is basically something that gives 0:09:34.960 --> 0:09:37.760 you a number depending on where you stand or where 0:09:37.800 --> 0:09:40.480 you are in space. That's right, Every point in space 0:09:40.720 --> 0:09:43.800 has a number associated with it with each field. So 0:09:43.840 --> 0:09:46.559 for example, the magnetic field from a magnet, there's a 0:09:46.640 --> 0:09:49.440 strength of that field. There's a field strength and every location. 0:09:49.559 --> 0:09:51.480 So as you're saying, you can ask what is the 0:09:51.520 --> 0:09:53.599 field strength here right next to the magnet and you 0:09:53.679 --> 0:09:56.480 get a number. What is the field strength way over there, 0:09:56.559 --> 0:09:58.720 far away from the magnet, and you get a smaller number. 0:09:58.960 --> 0:10:01.800 So the magnetic fiel field has a number at every 0:10:01.840 --> 0:10:03.640 point in space. And you can have different kinds of 0:10:03.679 --> 0:10:05.559 fields you can feel that just have a number. Those 0:10:05.559 --> 0:10:07.640 are called scale or fields. That's just a fancy way 0:10:07.679 --> 0:10:10.600 of saying a number, or you can have vector fields. 0:10:10.600 --> 0:10:12.360 You can have a field where at every point you 0:10:12.400 --> 0:10:15.400 have an arrow that points in a certain direction. It's 0:10:15.400 --> 0:10:17.360 like kind of like, are you saying it's a field 0:10:17.360 --> 0:10:19.600 that's kind of like a map, like it tells you 0:10:19.880 --> 0:10:22.440 what is it every position in space? Yeah? Or a 0:10:22.440 --> 0:10:27.000 map is kind of like a field actually, um, yeah, exactly. 0:10:27.000 --> 0:10:28.440 So you can think of for like a map is 0:10:28.600 --> 0:10:31.120 how much magnetic field is there here? How much magnetic 0:10:31.120 --> 0:10:34.160 field is there there? And you know everywhere in space 0:10:34.440 --> 0:10:37.400 there is magnetic field and easither you're strong or it's weak. Right, 0:10:37.440 --> 0:10:39.840 it can be if you're talking about like ordinary classical 0:10:39.880 --> 0:10:41.920 fields like from a hundred and fifty years ago, then 0:10:41.960 --> 0:10:44.720 they can be zero. Right, No magnets means there's a 0:10:44.760 --> 0:10:48.120 field there, but the field value is zero. So the 0:10:48.200 --> 0:10:51.200 question is is a field just like a map that 0:10:51.240 --> 0:10:53.440 we hold in our hands it tells these things? Or 0:10:53.480 --> 0:10:56.760 are we actually living on a map? Right? Like is 0:10:56.800 --> 0:10:59.719 a field a real thing of substance? Yeah? And the 0:10:59.760 --> 0:11:02.240 answer that question is we have no idea. And it's 0:11:02.280 --> 0:11:05.280 sort of a philosophical question more than a scientific one. Right. 0:11:05.760 --> 0:11:09.480 If you have a calculational tool a field that lets 0:11:09.520 --> 0:11:12.360 you predict the outcome of experiments and that works really 0:11:12.360 --> 0:11:16.000 really well. Doesn't matter if it's really physically true the 0:11:16.040 --> 0:11:19.440 thing that's happening, um or just or just a the 0:11:19.480 --> 0:11:23.800 way do you do these calculations? What's the difference? Right? Um? 0:11:24.160 --> 0:11:27.280 You know, if we weren't here with those fields exist, right, well, 0:11:27.280 --> 0:11:29.199 that's not really a question you can answer because if 0:11:29.200 --> 0:11:31.439 we weren't here, there'd be nobody to answer the question 0:11:31.520 --> 0:11:35.400 or do the experiment, right. So they're really tricky little 0:11:35.400 --> 0:11:39.319 philosophical puzzles. And that's a whole area of philosophical exploration 0:11:39.360 --> 0:11:42.720 that I'm totally not qualified to talk about, but I 0:11:42.760 --> 0:11:46.719 often do anyway that do. That's the basis of our 0:11:46.840 --> 0:11:49.520 entire podcast. That's the field of our podcast. Now, you know, 0:11:49.559 --> 0:11:54.800 there's a huge conflict between philosophers of science and physicists 0:11:55.000 --> 0:11:59.079 who think there's philosophers of science and spout off glibly 0:11:59.400 --> 0:12:03.520 sometimes um an uninformed way in front of mass audiences 0:12:03.760 --> 0:12:06.600 and then get taken down by actual philosophers of science. 0:12:08.600 --> 0:12:10.640 So that's a common mistake to make, which is why 0:12:10.640 --> 0:12:12.680 I wanted to put that qualifier out there. In the 0:12:12.720 --> 0:12:18.800 world economic war kind of between the pilosophers and physicists 0:12:18.800 --> 0:12:23.079 who venture into philosophy. Yes, exactly, exactly right. And there 0:12:23.080 --> 0:12:25.440 are some physicists who really have learned about philosophy and 0:12:25.440 --> 0:12:27.320 can speak knowledgeably about it. And then there are others 0:12:27.360 --> 0:12:29.520 who think they can speak knowledge of me about it 0:12:29.520 --> 0:12:31.880 but don't actually know anything. It sounds like an exciting fight, 0:12:32.720 --> 0:12:40.720 ironically speaking. All right, so, um, so that's a field. 0:12:40.720 --> 0:12:41.920 That's kind of what it is. It's kind of like 0:12:41.960 --> 0:12:46.040 a map of space that tells you something. Um, And 0:12:46.080 --> 0:12:49.320 then you can have particles in these fields, right, Like 0:12:49.480 --> 0:12:51.920 a particle is part of the field, or something can 0:12:51.920 --> 0:12:53.920 be on the field. Yes. One of the most interesting 0:12:53.960 --> 0:12:57.240 thing about field theories or theories of fields is it 0:12:57.280 --> 0:12:59.679 tells you that particles are not the most basic thing 0:12:59.679 --> 0:13:03.000 in the universe. The particles are, in fact, just vibrations 0:13:03.080 --> 0:13:05.960 of the field. Like particles are a real thing. Right, 0:13:06.280 --> 0:13:08.560 We feel them, we see them, we are them. But 0:13:08.640 --> 0:13:10.840 this tells us what they where they come from? Right 0:13:10.920 --> 0:13:12.560 the rules. It tells us that if you want to 0:13:12.600 --> 0:13:16.360 understand how particles move, you really have to understand these fields, 0:13:16.480 --> 0:13:20.560 because the particles are just vibrations in those fields, but 0:13:21.040 --> 0:13:25.360 vibrations of what of the fields? Right, Like the fields 0:13:25.400 --> 0:13:28.480 are you know, a thing and they vibrate, which means 0:13:28.520 --> 0:13:33.040 they have energy, right, and localized excitations of these fields. Right. 0:13:33.080 --> 0:13:36.120 Imagine for example, a big rubber sheet that fills the 0:13:36.200 --> 0:13:40.160 universe right, totally flat, but you could um poke it 0:13:40.320 --> 0:13:43.160 and send a wave through it, right, and that wave 0:13:43.360 --> 0:13:46.560 can travel. It's energy that's traveling by oscillating this field. 0:13:47.040 --> 0:13:50.079 And that's what particles are. There are oscillations in fields. 0:13:50.080 --> 0:13:53.080 But if I poke a sheet, it'll sort of dissipate, 0:13:53.120 --> 0:13:56.960 It'll go outwards and dissipate. A particle kind of likes 0:13:57.000 --> 0:13:58.840 to stay in one place. Well, I don't know what 0:13:58.920 --> 0:14:01.680 particles like. You've done any interviews with particles, and you 0:14:01.679 --> 0:14:07.680 can um, there's lots of waste of vibrated sheet, right, 0:14:07.720 --> 0:14:10.000 you can vibrted sheet, so you get a localized packet 0:14:10.000 --> 0:14:12.520 that's traveling. Right. It's easier to think about, for example, 0:14:12.559 --> 0:14:14.680 in one dimension, like instead of a sheet, think of 0:14:14.679 --> 0:14:16.920 a rope. Like if I'm holding a rope and you're 0:14:16.920 --> 0:14:18.960 holding a rope, I can wiggle it to send you 0:14:19.000 --> 0:14:21.240 like a little wiggle along the rope, so you can 0:14:21.280 --> 0:14:24.200 get a message. Right, And you're saying a particle is 0:14:24.240 --> 0:14:27.960 one of these wiggles. A particle is a localized excitation 0:14:28.040 --> 0:14:31.280 of the quantum field exactly. And the crazy thing is 0:14:31.320 --> 0:14:35.280 every particle has its own field. So like in the universe, 0:14:35.680 --> 0:14:39.240 everywhere there's an electron field, and everywhere there's an electron 0:14:39.400 --> 0:14:42.640 that's the electron field wiggling, wiggling, And there's also a 0:14:43.200 --> 0:14:46.240 um cork field, right, an upcork field. Everywhere there's an 0:14:46.280 --> 0:14:49.760 upcork The upcork field is wiggling. Like a particle is 0:14:49.800 --> 0:14:52.520 something that's causing the field to vibrate or it's like 0:14:52.680 --> 0:14:55.080 it is the vibration of the field. It is the 0:14:55.200 --> 0:14:59.720 vibration exactly, That's what it is. Yeah, And so that's 0:14:59.760 --> 0:15:01.800 what we're all made out of. Like you and I 0:15:01.840 --> 0:15:04.440 are made out of protons and quirks and electrons, and 0:15:04.480 --> 0:15:08.360 so we're all just like massive collections of little vibrations. 0:15:08.560 --> 0:15:11.840 That's right. It's all actually vibrations. Man, those dudes, that's 0:15:11.840 --> 0:15:17.560 not a vibrations were everything they were right in exactly. 0:15:17.560 --> 0:15:19.200 And so for if you like to think of yourself 0:15:19.240 --> 0:15:21.280 as made of particles, and you wonder like, well, what 0:15:21.320 --> 0:15:23.440 are the particles made out of? Right, I mean, they 0:15:23.480 --> 0:15:25.200 might be made out of smaller and smaller particles. But 0:15:25.200 --> 0:15:26.960 at some point you get down to the smallest particle 0:15:27.480 --> 0:15:29.480 and what's that particle made out of? And you think, oh, 0:15:29.680 --> 0:15:32.360 universe stuff. Well, it turns out the universe stuff might 0:15:32.400 --> 0:15:35.360 be quantum fields, right, that it's the quantum fields that 0:15:35.400 --> 0:15:38.120 are oscillating that make a particle. Okay, So that's a 0:15:38.160 --> 0:15:41.160 definition of a quantum field. It's it's the stuff of 0:15:41.200 --> 0:15:44.160 the universe. We're done. Yeah, So a field is just 0:15:44.240 --> 0:15:46.360 like a fluid field space. It could doesn't have to 0:15:46.360 --> 0:15:49.840 become quantum. It could be like electromagnetic or in any 0:15:49.880 --> 0:15:52.720 kind of field. But a quantum field is a field 0:15:52.760 --> 0:15:55.400 that describes the motion of a quantum object, like a particle. 0:15:55.680 --> 0:15:58.080 And so since we're dealing with particles and they move 0:15:58.080 --> 0:16:01.440 really fast and they have quantum entical properties, we deal 0:16:01.440 --> 0:16:06.280 with quantum fields. Okay, So a quantum field is what 0:16:06.440 --> 0:16:09.080 describes the things that we're made out of, right, because 0:16:09.080 --> 0:16:12.080 we're all made out of quantum particles, that's right, And 0:16:12.280 --> 0:16:14.680 every particle that makes us up is actually just a 0:16:14.760 --> 0:16:17.480 vibration of one of those fields, you know. And it's 0:16:17.480 --> 0:16:19.560 a really different way to look at the universe. Like 0:16:19.560 --> 0:16:22.440 when physicists started and they were thinking about quantum mechanics. 0:16:22.600 --> 0:16:24.960 They were thinking about, like what happens to a particle? 0:16:25.160 --> 0:16:28.720 You know what, what is this electron story? It starts 0:16:28.720 --> 0:16:30.600 off over here and then it goes off over there. 0:16:30.880 --> 0:16:32.720 And that's the way we're used to do in physics, right, 0:16:32.760 --> 0:16:35.080 Like you think about a ball, what happens to this 0:16:35.120 --> 0:16:37.440 ball as it rolls down the hill. It's very natural 0:16:37.480 --> 0:16:40.040 to sort of follow the story of the ball. So 0:16:40.080 --> 0:16:41.680 we tried to do that with us, follow the story. 0:16:41.680 --> 0:16:45.360 The electron problem is quantum particles don't behave like that, 0:16:45.400 --> 0:16:47.440 Like they don't have a path, right, It's not like 0:16:47.720 --> 0:16:50.040 you're here and then you're here and then you're here. 0:16:50.080 --> 0:16:53.240 Is all this uncertainty, But more than that, they're being 0:16:53.680 --> 0:16:56.760 destroyed and created all the time. Like an electron doesn't 0:16:56.760 --> 0:16:59.480 just fly through space. It flies through space, it turns 0:16:59.520 --> 0:17:01.520 into aton and something else, then it turns back into 0:17:01.520 --> 0:17:03.560 an electron, and then it creates this other thing which 0:17:03.760 --> 0:17:05.520 exists for a bill of second and then comes back. 0:17:05.760 --> 0:17:09.760 This is like frothing mass of stuff that's happening. And 0:17:09.800 --> 0:17:12.399 the quantum mechanics we first developed couldn't describe that at 0:17:12.400 --> 0:17:14.800 all because it was very difficult to describe the creation 0:17:14.920 --> 0:17:18.280 or destruction of particles. So you sort of like reboot 0:17:18.280 --> 0:17:21.679 your thinking completely and say, let's ignore the story of 0:17:21.720 --> 0:17:25.000 one particle and just think about like the particles in general. Right, 0:17:25.040 --> 0:17:28.040 let's think about all the particles. It's just like vibrations 0:17:28.080 --> 0:17:30.119 of this sheet that fills the universe. And then we 0:17:30.119 --> 0:17:32.080 don't have to worry about the story of particle A 0:17:32.200 --> 0:17:35.639 and the story of particle B. Because, um, you're saying 0:17:36.320 --> 0:17:38.720 an electron. If you think of it as a thing, 0:17:39.720 --> 0:17:42.200 and that thing disappears and turns into something else, then 0:17:42.240 --> 0:17:44.679 you're left wondering what happened to that thing? Yeah, Like 0:17:44.840 --> 0:17:47.680 Kevin the electron, what is his story? He disappeared and 0:17:47.680 --> 0:17:50.320 he came back. Is it's still Kevin? Right, Like in 0:17:50.400 --> 0:17:53.080 the quantum field theory version, Like all the electrons are 0:17:53.119 --> 0:17:55.440 Kevin because all the electrons are the same, right, Every 0:17:55.480 --> 0:17:58.760 electron is identical. Right, there's no difference between this electron 0:17:58.840 --> 0:18:02.040 and that electron. Where all Kevin, we're all made out 0:18:02.040 --> 0:18:04.440 of Kevin. Turns out that's the answer to the life, 0:18:04.480 --> 0:18:07.600 the universe and everything. Kevin. There's like twelve Kevin's listening 0:18:07.640 --> 0:18:10.919 to this, going, I knew it. I hope we have 0:18:11.000 --> 0:18:14.360 more than twelve Kevin's listening to this. Well, let's get 0:18:14.359 --> 0:18:16.560 a little bit deeper into it. But first let's take 0:18:16.600 --> 0:18:31.520 a quick break. Okay, so you're saying that the universe 0:18:32.200 --> 0:18:36.440 is not empty. It's like it's filled with these quantum 0:18:36.600 --> 0:18:40.040 fields that just kind of permeate everything. And they might 0:18:40.080 --> 0:18:42.680 be imaginary or they might be real things, but they 0:18:42.800 --> 0:18:47.080 premiate the entire universe. And we, like particles us matter, 0:18:47.520 --> 0:18:50.760 are just kind of like um little vibrations in these fields, 0:18:51.040 --> 0:18:53.879 that's right. And they lay on top of each other, right, 0:18:53.960 --> 0:18:57.119 Every point in space can have an electron field and 0:18:57.160 --> 0:18:59.359 an upcork field, and a down cork field, and a 0:18:59.400 --> 0:19:02.680 Higgs boson on field and electromagnetic field. We have lots 0:19:02.720 --> 0:19:05.120 of different kinds of fields, and you know, it might 0:19:05.119 --> 0:19:07.240 turn out eventually that we figure out how they're all 0:19:07.240 --> 0:19:09.280 really just part of one big field. But right now, 0:19:09.320 --> 0:19:11.400 we have lots of different kinds of fields that all 0:19:11.520 --> 0:19:13.240 sort of lay on top of each other. They're all 0:19:13.240 --> 0:19:15.120 the same size, or all the size of the universe. 0:19:15.240 --> 0:19:18.280 Every piece of space has all these fields, and some 0:19:18.359 --> 0:19:20.240 of them are zero ish, you know, they're low, and 0:19:20.280 --> 0:19:22.160 some of them have energy in them, which is why 0:19:22.200 --> 0:19:24.520 you have the electron here. So if you have like 0:19:24.560 --> 0:19:27.359 an electron on your left, that means the electron field 0:19:27.400 --> 0:19:29.199 is excited there. And if you have an upcork on 0:19:29.240 --> 0:19:31.760 your right, it means the upcork field is excited there 0:19:31.760 --> 0:19:34.399 and the electron field is not. Right. But and they 0:19:34.440 --> 0:19:36.920 can sort of talk to each other, right, Like an electron, 0:19:37.000 --> 0:19:39.359 you could have a little vibration in the electron field 0:19:39.840 --> 0:19:43.000 and then suddenly that disappears and it gets transferred to 0:19:43.600 --> 0:19:46.320 a different field and becomes a different particle exactly. And 0:19:46.359 --> 0:19:49.440 those are the forces. So quantum field theory can describe matter. 0:19:49.480 --> 0:19:51.520 That's what we've been talking about. They could also describe 0:19:51.520 --> 0:19:54.600 the forces like the electromagnetic field is a way for 0:19:54.800 --> 0:19:57.679 charge particle fields to interact with each other. Right, you 0:19:57.720 --> 0:20:00.880 have one electron over here, another electron over there. How 0:20:00.880 --> 0:20:02.639 do they talk to each other? Well, turns out the 0:20:02.640 --> 0:20:06.480 electron field and the photon field interact, and so one 0:20:06.480 --> 0:20:09.359 electron can talk to another electron by shooting a ripple 0:20:09.400 --> 0:20:12.080 through the photon field, which is like sending a photon 0:20:12.200 --> 0:20:16.359 between one electron and the other through another field. Yes, exactly, 0:20:16.400 --> 0:20:19.040 the fields coupled to each other, they interact otherwise would 0:20:19.080 --> 0:20:22.679 be pretty boring universe, and in these fields fill the 0:20:22.840 --> 0:20:25.880 entire universe. So are they related to space, like if 0:20:25.920 --> 0:20:29.680 if space grows, these fields grow as well. Yes, exactly, 0:20:29.720 --> 0:20:31.879 it's a basic part of space, right, you can't have 0:20:31.960 --> 0:20:34.480 space without these fields. As far as we know. There's 0:20:34.480 --> 0:20:37.240 no fieldless part of space, and every part of space 0:20:37.520 --> 0:20:40.680 has these fields. It's like there's a hum at every 0:20:40.680 --> 0:20:42.720 point in the universe. There's no quiet place in the 0:20:42.800 --> 0:20:44.960 universe exactly. And you might be thinking, well, what if 0:20:45.080 --> 0:20:46.720 you have an empty space, maybe all the fields are 0:20:46.800 --> 0:20:50.439 just zero. Right, Well, that's the fascinating thing about quantum fields, 0:20:50.560 --> 0:20:54.280 right because uncertainty principle, because there's a maximum amount of 0:20:54.320 --> 0:20:57.000 information you can have. You can't have quantum field to 0:20:57.000 --> 0:20:59.960 be exactly at zero. There's a minimum amount of inner 0:21:00.080 --> 0:21:02.719 g they have to have, so they can bubble and 0:21:02.760 --> 0:21:05.920 slosh in a way that gives you that uncertainty. Wait wait, wait, um, 0:21:06.000 --> 0:21:09.320