1 00:00:08,000 --> 00:00:09,879 Speaker 1: Hey, Daniel, do you think going to space will make 2 00:00:09,920 --> 00:00:11,360 Speaker 1: you older or younger? 3 00:00:12,240 --> 00:00:14,040 Speaker 2: I think it's going to be a rough trip, so 4 00:00:14,080 --> 00:00:16,720 Speaker 2: you'll probably come back feeling pretty worn down and older. 5 00:00:16,800 --> 00:00:19,160 Speaker 1: Yeah, but it's probably pretty exhilerating. So when don't you 6 00:00:19,200 --> 00:00:20,439 Speaker 1: come back younger in spirit? 7 00:00:23,280 --> 00:00:25,360 Speaker 2: I mean you might feel wiser, which is just going 8 00:00:25,440 --> 00:00:26,440 Speaker 2: to make you feel older. 9 00:00:26,560 --> 00:00:29,840 Speaker 1: Wiser is good. But what does physics say? What does 10 00:00:29,880 --> 00:00:31,680 Speaker 1: relativity say? If you go to space, are you going 11 00:00:31,720 --> 00:00:32,960 Speaker 1: to get older or younger? 12 00:00:33,080 --> 00:00:35,080 Speaker 2: Physics says you're going to be a tiny bit younger, 13 00:00:35,159 --> 00:00:37,960 Speaker 2: probably not enough to compensate for the decades of wear 14 00:00:38,000 --> 00:00:38,360 Speaker 2: and tear. 15 00:00:38,440 --> 00:00:40,920 Speaker 1: But you're in space and you're floating. What wears you 16 00:00:41,000 --> 00:00:46,080 Speaker 1: down the danger of dying at any moment. Perhaps that's 17 00:00:46,120 --> 00:00:47,560 Speaker 1: the same here on Earth. 18 00:00:48,200 --> 00:00:51,440 Speaker 2: The lack of gravity, the intense radiation, and yes, the 19 00:00:51,560 --> 00:00:54,360 Speaker 2: danger of dying, which is much higher up in space. 20 00:00:55,480 --> 00:00:58,040 Speaker 1: But if you can gain a second, I mean, isn't 21 00:00:58,160 --> 00:00:59,880 Speaker 1: time priceless? It's all we have. 22 00:01:00,040 --> 00:01:01,960 Speaker 2: You gain one second and you lose ten years. 23 00:01:02,080 --> 00:01:19,640 Speaker 1: But what of you? Hi? I'm Jorge, I'm a cartoonist 24 00:01:19,640 --> 00:01:21,640 Speaker 1: and the author of Oliver's Great Big Universe. 25 00:01:21,800 --> 00:01:24,320 Speaker 2: Hi, I'm Daniel I'm a particle physicist and a professor 26 00:01:24,400 --> 00:01:27,480 Speaker 2: at UC Irvine, and I'm gonna enjoy every second of 27 00:01:27,480 --> 00:01:28,360 Speaker 2: life here on Earth. 28 00:01:28,720 --> 00:01:32,680 Speaker 1: Yeah, presumably hopefully even these seconds where we are recording 29 00:01:32,680 --> 00:01:33,320 Speaker 1: this podcast. 30 00:01:33,440 --> 00:01:35,680 Speaker 2: Oh these are some of my favorite seconds. Absolutely. 31 00:01:35,840 --> 00:01:38,520 Speaker 1: Would you rather be like floating off an island in 32 00:01:38,520 --> 00:01:43,360 Speaker 1: the Pacific drinking some drinks? I mean, this is really cool, 33 00:01:43,760 --> 00:01:47,199 Speaker 1: But how does that compare sitting on a private island. 34 00:01:47,240 --> 00:01:49,240 Speaker 2: That would be so selfish, you know, just thinking about 35 00:01:49,240 --> 00:01:51,680 Speaker 2: my needs. We're here to talk about physics with everybody 36 00:01:51,680 --> 00:01:55,160 Speaker 2: and help everybody understand the universe better. That's so much 37 00:01:55,200 --> 00:01:55,800 Speaker 2: more valuable. 38 00:01:56,440 --> 00:01:59,360 Speaker 1: Well, actually, I am sitting in a pool in my 39 00:01:59,400 --> 00:02:02,240 Speaker 1: private island right now recording this, So I think I 40 00:02:02,240 --> 00:02:03,840 Speaker 1: think that means I win, is. 41 00:02:03,840 --> 00:02:05,680 Speaker 2: Your garage a private island or is it just like 42 00:02:05,680 --> 00:02:06,520 Speaker 2: a mental island. 43 00:02:06,840 --> 00:02:13,280 Speaker 1: I'm not a I am floating around somehow. 44 00:02:14,200 --> 00:02:15,760 Speaker 2: You're floating in cyberspace. 45 00:02:16,240 --> 00:02:18,720 Speaker 1: But anyways, welcome to our podcast, Daniel and Jorge Explain 46 00:02:18,800 --> 00:02:21,600 Speaker 1: the Universe, a production of iHeartRadio. 47 00:02:21,080 --> 00:02:22,960 Speaker 2: In which we float your brain through an ocean of 48 00:02:23,160 --> 00:02:26,600 Speaker 2: crazy physics ideas. We try to take you through the 49 00:02:26,639 --> 00:02:30,320 Speaker 2: private island of understanding, hoping to marinate your brain in 50 00:02:30,360 --> 00:02:34,200 Speaker 2: these ideas and percolate some of them down into your consciousness. 51 00:02:34,560 --> 00:02:37,399 Speaker 2: We think that the deepest questions in the universe, how 52 00:02:37,400 --> 00:02:40,080 Speaker 2: it started, how big is it, how it all works, 53 00:02:40,120 --> 00:02:43,000 Speaker 2: are things that can be understood and deserved to be understood, 54 00:02:43,200 --> 00:02:44,960 Speaker 2: or at the very least, we can explain to you 55 00:02:45,320 --> 00:02:47,600 Speaker 2: what we do and do not yet understand. 56 00:02:47,880 --> 00:02:49,840 Speaker 1: That's right, because it is an amazing universe, and we 57 00:02:49,960 --> 00:02:52,320 Speaker 1: like to take your sense of wonder on a vacation 58 00:02:52,600 --> 00:02:55,320 Speaker 1: siteeing through the universe and the cosmos, looking at things 59 00:02:55,360 --> 00:02:58,639 Speaker 1: that are already understood by humankind and things that are 60 00:02:58,680 --> 00:03:01,320 Speaker 1: still a huge. 61 00:03:00,600 --> 00:03:03,720 Speaker 2: Because science is a never ending list of questions, We're 62 00:03:03,760 --> 00:03:05,640 Speaker 2: always going to be curious about the way the world 63 00:03:05,680 --> 00:03:08,160 Speaker 2: works and why it is the way that it is. 64 00:03:08,200 --> 00:03:11,799 Speaker 2: And it's those questions that power science. Questions asked by 65 00:03:11,840 --> 00:03:14,200 Speaker 2: people working in the very forefront of human knowledge, and 66 00:03:14,400 --> 00:03:17,400 Speaker 2: questions asked by everybody looking up at the night sky 67 00:03:17,760 --> 00:03:20,760 Speaker 2: or looking down between their toes wanting to understand how 68 00:03:20,800 --> 00:03:21,640 Speaker 2: everything works. 69 00:03:21,960 --> 00:03:23,839 Speaker 1: Don't you ever want to take a vacation, Daniel from 70 00:03:23,840 --> 00:03:26,280 Speaker 1: asking questions? Well, I guess this podcast is sort of 71 00:03:26,280 --> 00:03:28,600 Speaker 1: your vacation, because you're answering questions. 72 00:03:29,560 --> 00:03:31,800 Speaker 2: Vacations are just more questions. Where should we go, how 73 00:03:31,880 --> 00:03:33,960 Speaker 2: should we organize it, how should we get there? What 74 00:03:34,000 --> 00:03:36,400 Speaker 2: should we eat tonight? There's no end of questions. 75 00:03:37,160 --> 00:03:40,360 Speaker 1: What should we not do? That's my favorite question on 76 00:03:40,400 --> 00:03:43,560 Speaker 1: a vacation. But yeah, the universe is full of questions. 77 00:03:43,640 --> 00:03:45,440 Speaker 1: Things we can ask about it, things we can wonder 78 00:03:45,480 --> 00:03:47,440 Speaker 1: about it, things we can try to find the answers to, 79 00:03:47,560 --> 00:03:50,240 Speaker 1: and sometimes on the podcast we like to answer these questions. 80 00:03:50,480 --> 00:03:52,720 Speaker 2: If you have questions about the nature of the universe, 81 00:03:52,800 --> 00:03:55,640 Speaker 2: how things work, or if ideas aren't just not clicking 82 00:03:55,680 --> 00:03:57,920 Speaker 2: in your mind right to us, we would love to 83 00:03:58,080 --> 00:04:01,320 Speaker 2: help you understand it. Answer all of our emails to 84 00:04:01,520 --> 00:04:05,840 Speaker 2: questions at Danielandjorge dot com. And sometimes I get a question, 85 00:04:05,960 --> 00:04:07,960 Speaker 2: I think, ooh, I bet other people want to hear 86 00:04:08,000 --> 00:04:09,960 Speaker 2: the answer to this, or I want to hear what 87 00:04:10,120 --> 00:04:13,160 Speaker 2: Jorge has to think or joke about this topic. So 88 00:04:13,200 --> 00:04:15,840 Speaker 2: then we answer them here on the podcast, so do. 89 00:04:15,760 --> 00:04:23,799 Speaker 1: They on the program we'll be tackling listener questions number 90 00:04:23,839 --> 00:04:26,880 Speaker 1: fifty five. Fifty five doesn't seem like a very big number, 91 00:04:26,920 --> 00:04:30,520 Speaker 1: but we are pretty deep into our production run. 92 00:04:31,800 --> 00:04:34,000 Speaker 2: Fifty five is a pretty big number. There are lots 93 00:04:34,000 --> 00:04:36,520 Speaker 2: of podcasts out there that don't even have fifty five episodes. 94 00:04:37,360 --> 00:04:38,960 Speaker 1: Fifty five seventy five. 95 00:04:40,960 --> 00:04:41,960 Speaker 2: Time to take a vacation. 96 00:04:43,320 --> 00:04:45,440 Speaker 1: But yeah, we'd like to ask our listener questions, and 97 00:04:45,480 --> 00:04:48,599 Speaker 1: so we have three great questions here about space travel, 98 00:04:48,920 --> 00:04:53,560 Speaker 1: but the nature of light, and about quasi particles, not 99 00:04:53,680 --> 00:04:58,920 Speaker 1: queasy particles, those are particularly uneasy. 100 00:05:00,040 --> 00:05:03,320 Speaker 2: We will not be talking about Burbon's today. 101 00:05:02,480 --> 00:05:07,200 Speaker 1: Yeah, or bar Fonds. But yeah, we have three awesome questions, 102 00:05:07,240 --> 00:05:09,080 Speaker 1: and so let's dive into our first one. This one 103 00:05:09,080 --> 00:05:09,920 Speaker 1: comes from Dan. 104 00:05:10,760 --> 00:05:13,240 Speaker 3: I'm Dan, and I have a question about space travel 105 00:05:13,279 --> 00:05:16,120 Speaker 3: and time. If we're able to send a spaceship to 106 00:05:16,120 --> 00:05:18,840 Speaker 3: Mars and back, wouldn't the astronauts be a different age 107 00:05:18,880 --> 00:05:21,520 Speaker 3: than the rest of us when they returned, And would 108 00:05:21,520 --> 00:05:24,039 Speaker 3: the difference be caused by how fast they traveled or 109 00:05:24,040 --> 00:05:25,119 Speaker 3: how long they were gone? 110 00:05:26,120 --> 00:05:29,159 Speaker 1: Interesting question from Dan. I guess the main thing is 111 00:05:29,160 --> 00:05:31,520 Speaker 1: is that a lot of people maybe associate space travel 112 00:05:32,160 --> 00:05:35,560 Speaker 1: with differences in time, like the famous twin Paradix. 113 00:05:36,360 --> 00:05:38,480 Speaker 2: Yeah, it sounds like Dan is planning a vacation in 114 00:05:38,560 --> 00:05:41,839 Speaker 2: Mars and he's wondering how many shirts he's got a pack, 115 00:05:41,960 --> 00:05:43,800 Speaker 2: how long will that trip be for him? 116 00:05:44,120 --> 00:05:46,600 Speaker 1: Yeah, I guess if he's not aging, he won't need 117 00:05:46,600 --> 00:05:49,680 Speaker 1: as many shirts, or he doesn't need to go to 118 00:05:49,720 --> 00:05:51,480 Speaker 1: that rejuvenating spot on Mars. 119 00:05:51,600 --> 00:05:53,880 Speaker 2: Or maybe he's wondering about renting his place out while 120 00:05:53,920 --> 00:05:56,200 Speaker 2: he's gone. If he's gone for one year, does he 121 00:05:56,240 --> 00:05:58,719 Speaker 2: need to AIRBNBA for two years? Or how does that 122 00:05:58,760 --> 00:05:59,120 Speaker 2: all work? 123 00:05:59,160 --> 00:06:01,760 Speaker 1: It's confusing here on Earth if you're changing time zones. 124 00:06:01,880 --> 00:06:05,000 Speaker 2: That's right, exactly. But then it is right to worry 125 00:06:05,000 --> 00:06:08,720 Speaker 2: about this because clocks do run differently out in space 126 00:06:08,760 --> 00:06:11,880 Speaker 2: and on space travel, but for two reasons, both of 127 00:06:11,880 --> 00:06:13,000 Speaker 2: which will affect the answer. 128 00:06:13,760 --> 00:06:16,520 Speaker 1: Interesting. There are multiple factors here that the universe throws 129 00:06:16,560 --> 00:06:16,960 Speaker 1: at you. 130 00:06:17,080 --> 00:06:20,560 Speaker 2: Yeah, there's two different ways that time can flow differently. 131 00:06:21,080 --> 00:06:25,080 Speaker 2: One is based on relative velocity moving clocks run slow, 132 00:06:25,560 --> 00:06:27,880 Speaker 2: and the other is an absolute one. It's just based 133 00:06:27,920 --> 00:06:31,800 Speaker 2: on space curvature. When space is bent, time is also bent, 134 00:06:32,040 --> 00:06:35,880 Speaker 2: so clocks tend to run more slowly when space is 135 00:06:36,000 --> 00:06:39,880 Speaker 2: more curved. These are two separate effects with different causes 136 00:06:40,200 --> 00:06:43,320 Speaker 2: and importantly different behaviors, but both of them will cause 137 00:06:43,360 --> 00:06:44,800 Speaker 2: clocks to run more slowly. 138 00:06:44,920 --> 00:06:46,920 Speaker 1: I meaning that time depends not just on how fast 139 00:06:46,960 --> 00:06:48,880 Speaker 1: you're moving, which is maybe the one people are more 140 00:06:48,920 --> 00:06:51,440 Speaker 1: familiar with, but also just how close you are to 141 00:06:51,600 --> 00:06:55,400 Speaker 1: heavy things, things that bend space and time, including. 142 00:06:54,960 --> 00:06:58,039 Speaker 2: The Earth, including the Earth, and including the Sun. This 143 00:06:58,160 --> 00:07:00,880 Speaker 2: is why, for example, if somebody is you're a black hole, 144 00:07:01,320 --> 00:07:04,600 Speaker 2: distant observers will see their time running super duper slowly, 145 00:07:04,920 --> 00:07:07,200 Speaker 2: not because they're moving at some high speed, but just 146 00:07:07,240 --> 00:07:10,160 Speaker 2: because they are in place of high curvature. They are 147 00:07:10,280 --> 00:07:14,400 Speaker 2: near a big, massive object, and time will run more slowly. 148 00:07:14,440 --> 00:07:18,680 Speaker 2: That's called gravitational time dilation. So there's velocity based time 149 00:07:18,720 --> 00:07:21,200 Speaker 2: dilation and gravitational time dilation. 150 00:07:22,320 --> 00:07:26,400 Speaker 1: Well, so then when you're leaving Earth, you're basically experiencing 151 00:07:26,480 --> 00:07:29,440 Speaker 1: both at different degrees and at different times, right, because 152 00:07:29,480 --> 00:07:32,040 Speaker 1: you're leaving the Earth, which is has a gravitational field, 153 00:07:32,360 --> 00:07:35,360 Speaker 1: but you're also going potentially really fast out there in space. 154 00:07:35,760 --> 00:07:38,000 Speaker 2: Yeah, exactly, And so it depends a little bit on 155 00:07:38,040 --> 00:07:41,120 Speaker 2: the details, but we can do some approximate calculations to 156 00:07:41,120 --> 00:07:42,200 Speaker 2: give Dan a rough answer. 157 00:07:42,360 --> 00:07:44,800 Speaker 1: All right, well, let's start with I guess the first 158 00:07:44,840 --> 00:07:47,640 Speaker 1: factor velocity. How fast do you think Dan is going 159 00:07:47,720 --> 00:07:48,160 Speaker 1: to Mars? 160 00:07:49,600 --> 00:07:51,440 Speaker 2: This is a good question. It depends a lot on 161 00:07:51,520 --> 00:07:54,080 Speaker 2: what you assume, but I thought, let's crank it to 162 00:07:54,160 --> 00:07:57,680 Speaker 2: the extreme. Let's think about like the fastest possible trip 163 00:07:57,760 --> 00:07:59,960 Speaker 2: you could make to Mars to have the most dramatic 164 00:08:00,120 --> 00:08:00,880 Speaker 2: impact on time. 165 00:08:01,080 --> 00:08:02,920 Speaker 1: You mean, like to calculate the speed, We're just going 166 00:08:02,960 --> 00:08:04,520 Speaker 1: to draw a straight line from here to Mars. 167 00:08:04,600 --> 00:08:06,320 Speaker 2: Yeah, and we're also going to assume that we have 168 00:08:06,560 --> 00:08:09,760 Speaker 2: super heavy duty engines and excellent power, because you could 169 00:08:09,800 --> 00:08:11,680 Speaker 2: get to Mars really slowly, Like you could go to 170 00:08:11,680 --> 00:08:13,840 Speaker 2: Mars at like walking speed, it would take you a 171 00:08:13,960 --> 00:08:17,240 Speaker 2: zillion years and you'd have no time dilation effects. Or 172 00:08:17,280 --> 00:08:19,160 Speaker 2: you could get to Mars super duper fast if you 173 00:08:19,160 --> 00:08:22,040 Speaker 2: have really powerful engines that push you up above a 174 00:08:22,080 --> 00:08:24,160 Speaker 2: tiny fraction of the speed of light, then you'd have 175 00:08:24,200 --> 00:08:27,480 Speaker 2: more time dilation effects. So the time dilation effects depend 176 00:08:27,600 --> 00:08:30,240 Speaker 2: on your top speed in the journey, which depends a 177 00:08:30,240 --> 00:08:32,240 Speaker 2: little bit on the technology you have to get to 178 00:08:32,280 --> 00:08:33,080 Speaker 2: that top speed. 179 00:08:34,040 --> 00:08:36,439 Speaker 1: But in reality, I guess when we send things to Mars, 180 00:08:36,679 --> 00:08:38,920 Speaker 1: they usually take this roundabout way, right, Like you try 181 00:08:38,960 --> 00:08:41,520 Speaker 1: to use orbital dynamics and you try to use maybe 182 00:08:41,559 --> 00:08:43,640 Speaker 1: the gravity of other planets to assist you and push 183 00:08:43,720 --> 00:08:45,680 Speaker 1: you along, and so it takes a while but even 184 00:08:45,679 --> 00:08:47,080 Speaker 1: though you're going pretty fast, Yeah, it. 185 00:08:47,080 --> 00:08:49,160 Speaker 2: Takes a while. It can take like six months to 186 00:08:49,200 --> 00:08:52,200 Speaker 2: get to Mars. And you are going pretty fast relative 187 00:08:52,240 --> 00:08:55,360 Speaker 2: to like the speed of a Lamborghini on Earth, but 188 00:08:55,400 --> 00:08:57,840 Speaker 2: you're not going very fast relative to the speed of light. 189 00:08:58,160 --> 00:09:00,520 Speaker 2: And that's the issue. And the speed of light is easy, 190 00:09:00,600 --> 00:09:03,600 Speaker 2: super duper fast, and to see real time dilation effects, 191 00:09:03,640 --> 00:09:05,280 Speaker 2: you got to get somewhere near the speed of light, 192 00:09:05,320 --> 00:09:07,880 Speaker 2: and that's pretty challenging. So I thought, how fast can 193 00:09:07,920 --> 00:09:10,080 Speaker 2: we get to Mars to maximize this effect? 194 00:09:10,160 --> 00:09:12,080 Speaker 1: I see you thought that it was not an interesting answer, 195 00:09:12,160 --> 00:09:13,440 Speaker 1: So let's crank it up. 196 00:09:13,559 --> 00:09:14,520 Speaker 2: Yeah, let's crak it up. 197 00:09:14,800 --> 00:09:16,040 Speaker 1: Crack it up and make it more fun. 198 00:09:16,240 --> 00:09:19,360 Speaker 2: Yeah, let's assume Elon Musk or somebody else develops like 199 00:09:19,480 --> 00:09:24,239 Speaker 2: a really powerful engine, one that uses like antimatter fuel, 200 00:09:24,559 --> 00:09:28,160 Speaker 2: that uses like antiprotons or anti electrons that totally annihilate 201 00:09:28,440 --> 00:09:32,839 Speaker 2: perfectly efficiently into energy and can pour that directly into 202 00:09:32,880 --> 00:09:34,960 Speaker 2: the acceleration of your spacecraft. 203 00:09:35,040 --> 00:09:36,880 Speaker 1: It doesn't have to be an antimatter engine. It just 204 00:09:36,920 --> 00:09:38,320 Speaker 1: has to be a powerful engine, right. 205 00:09:38,320 --> 00:09:40,320 Speaker 2: Just has to be a powerful engine. But you want 206 00:09:40,360 --> 00:09:43,280 Speaker 2: an efficient fuel source so that you minimize the amount 207 00:09:43,280 --> 00:09:45,560 Speaker 2: of fuel you have to bring along, so the fuel 208 00:09:45,640 --> 00:09:47,760 Speaker 2: is mostly pushing the spaceship and not the other fuel. 209 00:09:48,280 --> 00:09:50,840 Speaker 1: I feel like you're worrying about a real life consequences 210 00:09:50,840 --> 00:09:55,920 Speaker 1: in an imaginary scenario. Like I guess maybe you calculated 211 00:09:55,960 --> 00:09:57,280 Speaker 1: to the distance to Mars. 212 00:09:57,280 --> 00:09:59,680 Speaker 2: What's that distance at the closest approach the Earth to 213 00:09:59,679 --> 00:10:02,760 Speaker 2: Mars distance is about half of the Earth the Sun distance, 214 00:10:03,360 --> 00:10:05,400 Speaker 2: So it's like forty five million miles. 215 00:10:06,520 --> 00:10:08,480 Speaker 1: So we have a distance, and so how did you 216 00:10:08,559 --> 00:10:10,800 Speaker 1: calculate how fast we need to go to get there 217 00:10:11,440 --> 00:10:13,000 Speaker 1: in a reasonable scenario. 218 00:10:13,120 --> 00:10:15,040 Speaker 2: Well, I imagine that we could build an engine out 219 00:10:15,040 --> 00:10:17,000 Speaker 2: of anti matter, And I thought, what are the practical 220 00:10:17,040 --> 00:10:19,719 Speaker 2: limitations for launching that kind of ship? But how much 221 00:10:19,800 --> 00:10:22,640 Speaker 2: engine power could it produce? And you know, if you 222 00:10:22,760 --> 00:10:26,880 Speaker 2: spent like a few years generating antimatter, you'd have enough 223 00:10:26,880 --> 00:10:30,040 Speaker 2: engine power at launch that's like more than a thousand 224 00:10:30,080 --> 00:10:33,440 Speaker 2: times the electrical power output of the United States, which 225 00:10:33,440 --> 00:10:37,120 Speaker 2: would require like five tons or so of antimatter, which 226 00:10:37,160 --> 00:10:41,079 Speaker 2: is totally unrealistic. But if you did that, then you 227 00:10:41,120 --> 00:10:42,760 Speaker 2: would be able to get to Mars in just a 228 00:10:42,760 --> 00:10:46,040 Speaker 2: couple of days. Like that kind of super powerful engine 229 00:10:46,080 --> 00:10:47,920 Speaker 2: would get you up to like a third of one 230 00:10:48,000 --> 00:10:50,680 Speaker 2: percent of the speed of light for a pretty zippy 231 00:10:50,720 --> 00:10:51,440 Speaker 2: trip to Mars. 232 00:10:51,600 --> 00:10:54,320 Speaker 1: Would that run into like acceleration limits, Like our bodies 233 00:10:54,320 --> 00:10:56,200 Speaker 1: can only tolerate so many g's. 234 00:10:56,520 --> 00:10:59,520 Speaker 2: That's right, humans can only tolerate like eight to ten 235 00:10:59,640 --> 00:11:03,120 Speaker 2: g and even that's pretty extreme. So I was assuming 236 00:11:03,160 --> 00:11:05,600 Speaker 2: we have like super robust astronauts that can tolerate about 237 00:11:05,640 --> 00:11:06,480 Speaker 2: eight to ten gs. 238 00:11:06,800 --> 00:11:09,040 Speaker 1: Okay, so then you calculated the trip for Dan and 239 00:11:09,320 --> 00:11:13,520 Speaker 1: you get up to about point to eight c's. 240 00:11:13,800 --> 00:11:16,200 Speaker 2: Yeah exactly. Then that's at the halfway point because you've 241 00:11:16,200 --> 00:11:17,600 Speaker 2: got to speed up and then you're going to turn 242 00:11:17,600 --> 00:11:19,400 Speaker 2: around and slow down so that when you get to 243 00:11:19,400 --> 00:11:22,280 Speaker 2: Mars you're not just zipping by it at half a 244 00:11:22,280 --> 00:11:24,480 Speaker 2: percent of the speed of light, because that's kind of 245 00:11:24,480 --> 00:11:27,040 Speaker 2: beside the point. So this top speed is at the 246 00:11:27,080 --> 00:11:27,959 Speaker 2: halfway point. 247 00:11:28,160 --> 00:11:30,240 Speaker 1: Now, this is a very small percentage of the speed 248 00:11:30,280 --> 00:11:32,439 Speaker 1: of light, less than a third of a percent. So 249 00:11:32,440 --> 00:11:35,440 Speaker 1: I'm guessing maybe time didn't move that much slower for 250 00:11:36,080 --> 00:11:37,920 Speaker 1: Dan because of the speed. 251 00:11:37,720 --> 00:11:41,160 Speaker 2: Yeah exactly. And relativity is very nonlinear, so if you're 252 00:11:41,160 --> 00:11:44,280 Speaker 2: still at very low velocities, there's basically no effect. The 253 00:11:44,280 --> 00:11:46,800 Speaker 2: effect gets stronger as you get closer to the speed 254 00:11:46,800 --> 00:11:48,560 Speaker 2: of light. As you get very close to the speed 255 00:11:48,600 --> 00:11:51,240 Speaker 2: of light, it gets much more dramatic. So when you're 256 00:11:51,240 --> 00:11:54,920 Speaker 2: going at this pretty respectable speed compared to Lamborghinians on Earth, 257 00:11:54,920 --> 00:11:57,800 Speaker 2: but still very very slow compared to photons. 258 00:11:57,360 --> 00:11:59,400 Speaker 1: How fast are we going relative to a Lamborghini. 259 00:12:00,800 --> 00:12:04,440 Speaker 2: Yeah, so that's about eight hundred and forty thousand meters 260 00:12:04,480 --> 00:12:09,080 Speaker 2: per second, which is something like one point eight million 261 00:12:09,360 --> 00:12:12,480 Speaker 2: miles per hour, so a lot faster than a Lamborghini. 262 00:12:12,960 --> 00:12:15,560 Speaker 1: Yeah, by a large amount. But even though you're going 263 00:12:15,600 --> 00:12:18,400 Speaker 1: over a million miles per hour, the time dilation is 264 00:12:18,440 --> 00:12:19,400 Speaker 1: not dead much. 265 00:12:19,559 --> 00:12:24,160 Speaker 2: The time dollation factor is one point zero zero zero 266 00:12:24,280 --> 00:12:29,360 Speaker 2: zero zero four, meaning like every million seconds somebody traveling 267 00:12:29,400 --> 00:12:32,920 Speaker 2: at that speed experiences four seconds fewer at the peak speed. 268 00:12:33,120 --> 00:12:34,040 Speaker 2: At the peak speed. 269 00:12:34,120 --> 00:12:36,040 Speaker 1: Yeah, but Dan is not going at the peak speed 270 00:12:36,040 --> 00:12:37,960 Speaker 1: the whole time. So like if he goes around back, 271 00:12:38,000 --> 00:12:41,080 Speaker 1: how much time is a younger relative to his twin 272 00:12:41,120 --> 00:12:42,880 Speaker 1: who was born at the same time here on Earth 273 00:12:43,000 --> 00:12:43,719 Speaker 1: and that didn't go. 274 00:12:43,760 --> 00:12:45,480 Speaker 2: If he goes there in forty eight hours and back 275 00:12:45,520 --> 00:12:48,520 Speaker 2: in forty eight hours, that's like roughly one hundred hours, 276 00:12:48,520 --> 00:12:51,480 Speaker 2: which is not even a million seconds, so the difference 277 00:12:51,600 --> 00:12:53,640 Speaker 2: is going to be less than a second overall. 278 00:12:53,679 --> 00:12:56,000 Speaker 1: But he's also had to accelerate up to the speed 279 00:12:56,040 --> 00:12:59,120 Speaker 1: and accelerate down to zero, so it's probably even less 280 00:12:59,120 --> 00:13:01,360 Speaker 1: than that, maybe maybe like a tenth of that. 281 00:13:01,640 --> 00:13:03,520 Speaker 2: Yeah, it's going to be less than a second for sure. 282 00:13:03,640 --> 00:13:06,880 Speaker 1: So Dan's gonna go to Mars come back. He's going 283 00:13:06,960 --> 00:13:09,280 Speaker 1: to be at eight to ten g's the whole time, 284 00:13:10,480 --> 00:13:13,079 Speaker 1: and he'll only be younger by about less than a second. 285 00:13:13,160 --> 00:13:16,400 Speaker 2: Yeah, less than a second, exactly. That's only considering the 286 00:13:16,440 --> 00:13:17,920 Speaker 2: velocity effects. 287 00:13:17,600 --> 00:13:19,839 Speaker 1: Right right, like starting from orbit or something. 288 00:13:19,920 --> 00:13:23,679 Speaker 2: Mm hmm, exactly, that's not considering the gravitational time dilation. 289 00:13:24,120 --> 00:13:25,800 Speaker 1: All right, Well let's get into that. What are the 290 00:13:25,800 --> 00:13:29,000 Speaker 1: gravitational effects of a time due to gravity? 291 00:13:29,200 --> 00:13:31,720 Speaker 2: So there's two effects here to think about. One is 292 00:13:31,760 --> 00:13:35,160 Speaker 2: that you're leaving Earth's gravity and time passes more slowly 293 00:13:35,200 --> 00:13:38,080 Speaker 2: when you're close to earth gravity. We know this because 294 00:13:38,120 --> 00:13:41,800 Speaker 2: like satellites in orbit that keep our GPS systems in sync, 295 00:13:42,320 --> 00:13:45,160 Speaker 2: their clocks run faster than clocks on Earth. This is 296 00:13:45,160 --> 00:13:47,720 Speaker 2: something we've measured, so we know this very very well. 297 00:13:47,880 --> 00:13:50,120 Speaker 1: They've measured this in with mountains too, right, like you 298 00:13:50,160 --> 00:13:52,079 Speaker 1: can tell the difference between someone at the bottom of 299 00:13:52,120 --> 00:13:54,240 Speaker 1: a mountain and a clock running at the top of 300 00:13:54,240 --> 00:13:54,680 Speaker 1: the mountain. 301 00:13:54,800 --> 00:13:56,920 Speaker 2: Yeah, exactly. They have atomic clocks that are like two 302 00:13:56,960 --> 00:13:59,480 Speaker 2: meters apart in altitude, and they can tell the difference 303 00:13:59,520 --> 00:14:02,200 Speaker 2: in how they run. It's very very precise. It's super awesome. 304 00:14:02,360 --> 00:14:04,680 Speaker 1: Yeah, which means like your feet are moving through time 305 00:14:04,800 --> 00:14:07,040 Speaker 1: slower than your head if you're standing up. 306 00:14:07,520 --> 00:14:10,920 Speaker 2: Yes, but the size of this effect is tiny. Like 307 00:14:11,080 --> 00:14:13,960 Speaker 2: time passes on Earth more slowly than out in deep 308 00:14:13,960 --> 00:14:18,680 Speaker 2: space by like point seven parts per billion. That means 309 00:14:18,720 --> 00:14:20,920 Speaker 2: in a billion seconds, time on Earth will have ticked 310 00:14:20,920 --> 00:14:23,080 Speaker 2: by point seven seconds more slowly. 311 00:14:23,240 --> 00:14:25,840 Speaker 1: So if Dan just went up to orbit Earth's orbit, 312 00:14:26,120 --> 00:14:28,320 Speaker 1: we would be a little bit younger, but not by much, 313 00:14:28,480 --> 00:14:30,040 Speaker 1: Like I have a part per billion. 314 00:14:30,040 --> 00:14:33,720 Speaker 2: Yeah exactly. A billion seconds is like thirty two years, 315 00:14:34,280 --> 00:14:36,360 Speaker 2: So if you've been thirty two years, like in deep 316 00:14:36,400 --> 00:14:38,760 Speaker 2: deep orbit, then your clock will have run faster by 317 00:14:38,800 --> 00:14:39,400 Speaker 2: one second. 318 00:14:39,720 --> 00:14:41,480 Speaker 1: So it's a very negligible effect. 319 00:14:41,640 --> 00:14:43,320 Speaker 2: It's not I don't know if it's negligible, and you 320 00:14:43,360 --> 00:14:45,920 Speaker 2: can measure it with very precise devices, but it's real. 321 00:14:46,360 --> 00:14:49,720 Speaker 2: And the interesting thing is that Mars has lower gravity 322 00:14:49,840 --> 00:14:51,960 Speaker 2: than Earth. Right, it's a smaller planet, so on the 323 00:14:51,960 --> 00:14:55,080 Speaker 2: surface the gravity is not as intense, and so this 324 00:14:55,200 --> 00:14:58,120 Speaker 2: same effect on Earth that's like point seven parts per 325 00:14:58,160 --> 00:15:02,120 Speaker 2: billion is only point one four parts per billion on Mars. 326 00:15:02,960 --> 00:15:04,760 Speaker 2: So if you go to Mars and spend a lot 327 00:15:04,800 --> 00:15:08,480 Speaker 2: of time there, your clock will run faster than clocks 328 00:15:08,560 --> 00:15:10,800 Speaker 2: on Earth because you're not as deep in a gravity. 329 00:15:10,840 --> 00:15:13,480 Speaker 1: Well, well you're aging faster in Mars. 330 00:15:13,720 --> 00:15:16,600 Speaker 2: You're aging faster on Mars exactly. But that's actually not 331 00:15:16,600 --> 00:15:20,640 Speaker 2: even the biggest gravitational effect. Mars is further away from 332 00:15:20,640 --> 00:15:23,400 Speaker 2: the Sun, so the Sun's gravity is weaker at Mars 333 00:15:23,440 --> 00:15:26,160 Speaker 2: than it is on Earth. This is actually a bigger 334 00:15:26,200 --> 00:15:30,360 Speaker 2: effect than the difference between Earth and Mars. Sun's gravity 335 00:15:30,400 --> 00:15:33,200 Speaker 2: causes a seven parts per billion effect on Mars and 336 00:15:33,240 --> 00:15:35,600 Speaker 2: a ten parts per billion effect on. 337 00:15:35,560 --> 00:15:38,920 Speaker 1: Earth, meaning from the suns to gravity, you're aging faster 338 00:15:39,040 --> 00:15:39,520 Speaker 1: in Mars. 339 00:15:39,560 --> 00:15:42,760 Speaker 2: Also, yeah, that's right, you're aging faster on Mars because 340 00:15:42,840 --> 00:15:45,680 Speaker 2: its gravity is weaker and because you're further from the 341 00:15:45,720 --> 00:15:48,920 Speaker 2: Sun's gravity. Overall, this effect is like six parts per 342 00:15:48,960 --> 00:15:50,200 Speaker 2: billion on Mars. 343 00:15:50,920 --> 00:15:53,720 Speaker 1: Okay, so then what's the grand total for that? It 344 00:15:53,720 --> 00:15:56,080 Speaker 1: seems like he's gonna gain a little bit of time 345 00:15:56,160 --> 00:15:58,240 Speaker 1: due to velocity going to Mars and back, but he's 346 00:15:58,240 --> 00:16:01,320 Speaker 1: gonna lose a little bit of time by being further 347 00:16:01,320 --> 00:16:04,160 Speaker 1: away from the Sun and by being around a planet 348 00:16:04,200 --> 00:16:06,119 Speaker 1: that's smaller. What's the grand total. 349 00:16:05,880 --> 00:16:08,280 Speaker 2: Well, it depends on how much time he spends there. Right, 350 00:16:08,320 --> 00:16:10,640 Speaker 2: If he just goes there and back, there's basically no 351 00:16:10,720 --> 00:16:13,720 Speaker 2: effect from gravitational curvature. But if he goes there and 352 00:16:13,760 --> 00:16:16,160 Speaker 2: lives there for like a thousand years, then he's going 353 00:16:16,160 --> 00:16:19,280 Speaker 2: to accumulate some effect from the curvature. So it depends 354 00:16:19,320 --> 00:16:20,720 Speaker 2: on how much time he spends there. 355 00:16:20,600 --> 00:16:24,359 Speaker 1: On Mars, depends on how long he books that Airbnb exactly. 356 00:16:24,920 --> 00:16:28,480 Speaker 2: But the overall story is that these are tiny, tiny effects. 357 00:16:28,720 --> 00:16:30,920 Speaker 2: You'd be a challenge to measure these things. You'd need 358 00:16:31,040 --> 00:16:33,920 Speaker 2: very precise devices. But in the assumption that we could 359 00:16:33,920 --> 00:16:36,240 Speaker 2: build crazy powerful engines that get us to Mars in 360 00:16:36,240 --> 00:16:39,600 Speaker 2: two days, then the time dilation effects are going to 361 00:16:39,600 --> 00:16:42,520 Speaker 2: be the most dramatic. But even those are parts per million. 362 00:16:44,000 --> 00:16:47,520 Speaker 1: Yeah, they're super tiny, but what's interesting is that they're there, right, 363 00:16:47,520 --> 00:16:50,200 Speaker 1: They're measurable. Like if we synchronize our clocks and you 364 00:16:50,400 --> 00:16:52,640 Speaker 1: went out there and came back like our clocks would 365 00:16:52,680 --> 00:16:53,080 Speaker 1: be off. 366 00:16:53,200 --> 00:16:54,800 Speaker 2: Yeah, and it really reveals that we live in an 367 00:16:54,840 --> 00:16:58,360 Speaker 2: unusual set of circumstances. You know, we're not living near 368 00:16:58,560 --> 00:17:02,440 Speaker 2: very strong gravity, not traveling at very high speeds, and 369 00:17:02,480 --> 00:17:06,080 Speaker 2: so our clocks are mostly just synchronized. But there are 370 00:17:06,119 --> 00:17:08,960 Speaker 2: places in our universe with extreme gravity where things are 371 00:17:09,000 --> 00:17:11,840 Speaker 2: traveling at very high speeds relative to each other, and 372 00:17:11,880 --> 00:17:13,320 Speaker 2: their clocks are much creasier. 373 00:17:13,920 --> 00:17:15,760 Speaker 1: All right, Well, I guess then the answer for Dan 374 00:17:15,960 --> 00:17:18,879 Speaker 1: is that he's much better off vacationing here with me, 375 00:17:19,000 --> 00:17:21,880 Speaker 1: my private island floating at the pool, than by going 376 00:17:21,880 --> 00:17:24,680 Speaker 1: to Mars. I think my mojito will probably take more 377 00:17:24,720 --> 00:17:27,760 Speaker 1: time off with his overall age than then going to 378 00:17:27,800 --> 00:17:29,800 Speaker 1: space and then with an antimatter engine. 379 00:17:30,080 --> 00:17:33,520 Speaker 2: Yeah, that's right, His mojito will melt one second slower 380 00:17:33,880 --> 00:17:35,160 Speaker 2: after a million mohidos. 381 00:17:35,920 --> 00:17:38,080 Speaker 1: Well, it'd be hard to drink it going at eight 382 00:17:38,119 --> 00:17:43,119 Speaker 1: to ten g's. So again, come join me, Dan, This 383 00:17:43,200 --> 00:17:45,000 Speaker 1: is much more comfortable here. 384 00:17:45,080 --> 00:17:47,119 Speaker 2: Dan, you just scored an invitation. Wow. 385 00:17:47,359 --> 00:17:49,480 Speaker 1: Yeah, of course I don't know your last name, Dan, 386 00:17:49,520 --> 00:17:56,280 Speaker 1: so I'm just gonna ignore all emails from Dan's I 387 00:17:56,280 --> 00:17:59,959 Speaker 1: don't I know which one asked the question, where's this Dan, Dan? 388 00:18:00,840 --> 00:18:02,240 Speaker 1: Did I just invite you to my island? 389 00:18:04,680 --> 00:18:06,560 Speaker 2: Yes? This is my alter ego, Dan. 390 00:18:07,400 --> 00:18:09,520 Speaker 1: This is your twin, the twin that I wanted to 391 00:18:09,560 --> 00:18:10,320 Speaker 1: go to space. 392 00:18:10,080 --> 00:18:11,880 Speaker 2: When I take off my glasses, I'm Dan. 393 00:18:13,880 --> 00:18:17,360 Speaker 1: It's the twin parad doctor. All right, Well, let's get 394 00:18:17,359 --> 00:18:19,400 Speaker 1: to our two other questions. We have an awesome question 395 00:18:19,440 --> 00:18:23,040 Speaker 1: here about the nature of light and one about quasi 396 00:18:23,080 --> 00:18:27,159 Speaker 1: particles and crossword puzzles. So we'll get to that clue. 397 00:18:27,160 --> 00:18:41,960 Speaker 1: But first, let's take a quick break. All right, we're 398 00:18:41,960 --> 00:18:45,280 Speaker 1: asking listener questions here today and inviting people to our 399 00:18:45,280 --> 00:18:48,000 Speaker 1: private island. Apparently. All right, we have a great question 400 00:18:48,080 --> 00:18:52,280 Speaker 1: here from John Lopez about the reality and nature of light. 401 00:18:53,119 --> 00:18:54,359 Speaker 2: Hi, Daniel len Jorge. 402 00:18:55,040 --> 00:18:57,720 Speaker 4: My question is what is the physical reality of a 403 00:18:57,800 --> 00:19:00,600 Speaker 4: wavelength of light? Like, what is it like to have 404 00:19:00,640 --> 00:19:04,840 Speaker 4: a wavelength of nanometers versus a wavelength of tens of 405 00:19:04,920 --> 00:19:05,520 Speaker 4: meters long? 406 00:19:06,680 --> 00:19:07,240 Speaker 2: On the graph? 407 00:19:07,280 --> 00:19:10,080 Speaker 4: I know we represent it as the pigs and valleys 408 00:19:10,119 --> 00:19:13,960 Speaker 4: all stretched out, but what does this mean in real life? 409 00:19:14,240 --> 00:19:18,800 Speaker 4: For example, in microwaves, mesh holes block microwaves because their 410 00:19:18,840 --> 00:19:22,240 Speaker 4: wavelength is longer than the size of the holes. The 411 00:19:22,359 --> 00:19:26,200 Speaker 4: visible light passes through because the wavelength is so much smaller. 412 00:19:26,720 --> 00:19:30,640 Speaker 4: So in reality, in wavelength must be something different than 413 00:19:31,000 --> 00:19:35,000 Speaker 4: stretched out pigs and valleys, because otherwise it seems like 414 00:19:35,040 --> 00:19:37,280 Speaker 4: both could pass through the holes. 415 00:19:37,400 --> 00:19:42,440 Speaker 1: Just fine, All right, great question. Basically, what exactly is light? 416 00:19:42,680 --> 00:19:46,240 Speaker 1: Is the question? Can you shed some light on this topic. 417 00:19:46,640 --> 00:19:48,720 Speaker 2: I love this question because it's clear to me that 418 00:19:48,800 --> 00:19:50,960 Speaker 2: John is trying to like build a mental picture in 419 00:19:51,040 --> 00:19:53,520 Speaker 2: his Mind's trying to think about what happens in the 420 00:19:53,600 --> 00:19:56,840 Speaker 2: universe and trying to describe it mentally, thinking about like 421 00:19:57,160 --> 00:20:00,679 Speaker 2: are the photon zigging and zagging is like really wiggling sideways? 422 00:20:00,720 --> 00:20:03,399 Speaker 2: What is actually going on? How to think about this stuff? 423 00:20:03,640 --> 00:20:06,119 Speaker 2: It's really important that you build this mental model in 424 00:20:06,160 --> 00:20:08,760 Speaker 2: your head. That's what physics is. So I love hearing 425 00:20:08,840 --> 00:20:11,520 Speaker 2: him doing physics in his mind, trying to link it 426 00:20:11,560 --> 00:20:13,520 Speaker 2: all together to get a coherent picture. It's perfect. 427 00:20:13,680 --> 00:20:15,080 Speaker 1: Yeah, I guess he's trying to get it like an 428 00:20:15,119 --> 00:20:17,879 Speaker 1: intuitive sense of what light is like, Like if you 429 00:20:17,920 --> 00:20:20,760 Speaker 1: were shrunk down to the small level of quantum level, 430 00:20:20,760 --> 00:20:22,440 Speaker 1: what would it be like to experience light? 431 00:20:22,640 --> 00:20:24,800 Speaker 2: Yeah, that's a great question, and you know, fundamentally we 432 00:20:24,880 --> 00:20:28,200 Speaker 2: don't know what light is. Quantum mechanical things are very 433 00:20:28,200 --> 00:20:31,359 Speaker 2: hard to visualize and to think about. But John's question 434 00:20:31,520 --> 00:20:35,400 Speaker 2: actually is more about like classical physics, like thinking about 435 00:20:35,480 --> 00:20:39,320 Speaker 2: light in terms of electromagnetic waves, you know, the peaks 436 00:20:39,359 --> 00:20:41,800 Speaker 2: and the valley and the wiggles, and why that means 437 00:20:41,840 --> 00:20:44,040 Speaker 2: your microwave is not frying your brain even if you 438 00:20:44,080 --> 00:20:46,200 Speaker 2: stick your nose against it while you're cooking your popcorn 439 00:20:46,359 --> 00:20:50,960 Speaker 2: that you know of, Maybe that's why my brain is fried. 440 00:20:51,000 --> 00:20:52,240 Speaker 2: Oh my gosh. 441 00:20:52,320 --> 00:20:55,800 Speaker 1: Yeah, you're too impatient from the popcorn there to go 442 00:20:55,920 --> 00:20:59,359 Speaker 1: to Mars, take a vacation, come back. It'll be ready 443 00:20:59,359 --> 00:20:59,560 Speaker 1: for you. 444 00:20:59,640 --> 00:21:01,440 Speaker 2: And I think is a lot to learn in terms 445 00:21:01,440 --> 00:21:04,119 Speaker 2: of how to think about light as wiggles in the 446 00:21:04,160 --> 00:21:07,520 Speaker 2: electromagnetic field, because I hear a lot of misconceptions out 447 00:21:07,560 --> 00:21:10,639 Speaker 2: there and actually a lot of mistakes in popular descriptions 448 00:21:10,680 --> 00:21:12,680 Speaker 2: of how light works. So I think we can clear 449 00:21:12,720 --> 00:21:15,159 Speaker 2: up a lot of those misunderstandings, even just in the 450 00:21:15,200 --> 00:21:19,040 Speaker 2: classical picture, ignoring quantum effects, not thinking about photons, just 451 00:21:19,080 --> 00:21:22,399 Speaker 2: thinking about light as an oscillation in the electromagnetic field. 452 00:21:22,640 --> 00:21:25,160 Speaker 1: WHOA, Okay, So this is confusing me a little bit 453 00:21:25,600 --> 00:21:27,840 Speaker 1: because I think maybe what I know what a lot 454 00:21:27,840 --> 00:21:29,840 Speaker 1: of people know is that light is both a particle 455 00:21:29,960 --> 00:21:32,240 Speaker 1: and a wave, right Like, that's kind of one of 456 00:21:32,240 --> 00:21:34,840 Speaker 1: the dualities that physics found out at some point. So 457 00:21:34,880 --> 00:21:36,879 Speaker 1: you're saying, let's ignore the fact that it's a particle, 458 00:21:36,960 --> 00:21:39,680 Speaker 1: or are we just going back in time and forgetting 459 00:21:39,760 --> 00:21:40,480 Speaker 1: quantum physics. 460 00:21:40,560 --> 00:21:42,760 Speaker 2: We're going back in time and forgetting quantum physics because 461 00:21:42,760 --> 00:21:45,639 Speaker 2: we don't need quantum physics to explain this effect. The 462 00:21:45,720 --> 00:21:48,120 Speaker 2: reason your microwave works and the reason that doesn't fry 463 00:21:48,119 --> 00:21:51,400 Speaker 2: your brain can be explained using purely classical physics. 464 00:21:51,400 --> 00:21:53,600 Speaker 1: So when you're talking about the wavelength of light as 465 00:21:53,600 --> 00:21:56,359 Speaker 1: a wave in classical physics, is that the same wave 466 00:21:56,520 --> 00:21:59,960 Speaker 1: as when you're talking about quantum physics and things having 467 00:22:00,080 --> 00:22:01,400 Speaker 1: a wave function for example? 468 00:22:01,560 --> 00:22:04,760 Speaker 2: There's an evolution there from one idea to the other idea. Absolutely, 469 00:22:05,480 --> 00:22:07,399 Speaker 2: But we don't need to go into quantum physics for 470 00:22:07,480 --> 00:22:10,560 Speaker 2: this answer. And that's all digression. And you might think, 471 00:22:10,560 --> 00:22:12,320 Speaker 2: hold on a second, but you know the world is quantum, 472 00:22:12,400 --> 00:22:14,760 Speaker 2: how can you do that? But you know, physics is 473 00:22:14,800 --> 00:22:17,320 Speaker 2: all about making approximations. None of our theories of the 474 00:22:17,400 --> 00:22:20,359 Speaker 2: universe are exact and perfect. They ignore quantum gravity, because 475 00:22:20,359 --> 00:22:22,680 Speaker 2: we don't understand it. But you only need to apply 476 00:22:22,760 --> 00:22:25,000 Speaker 2: the physics. You need to answer the question like if 477 00:22:25,000 --> 00:22:27,000 Speaker 2: somebody asks, is this canniball going to make it over 478 00:22:27,040 --> 00:22:29,960 Speaker 2: that castle wall? You don't need to do quantum calculations. 479 00:22:29,960 --> 00:22:32,679 Speaker 2: You just need F equals MA. So part of doing 480 00:22:32,720 --> 00:22:35,720 Speaker 2: physics is applying physics judiciously. And in this case we 481 00:22:35,760 --> 00:22:39,159 Speaker 2: can just think about like Maxwell's understanding of photons and 482 00:22:39,240 --> 00:22:41,639 Speaker 2: light as waves in the electromagnetic field. 483 00:22:41,920 --> 00:22:44,240 Speaker 1: Well, I imagine John is curious and it seems like from 484 00:22:44,240 --> 00:22:47,159 Speaker 1: his question he is about the nature of light. Yeah, so, 485 00:22:47,359 --> 00:22:49,879 Speaker 1: like is light a wave? Is light a not a wave? 486 00:22:50,280 --> 00:22:51,960 Speaker 1: We can think of it as not a wave or 487 00:22:52,080 --> 00:22:54,040 Speaker 1: as a wave or only a wave. What is the 488 00:22:54,080 --> 00:22:55,680 Speaker 1: classical picture of light? 489 00:22:55,920 --> 00:22:58,520 Speaker 2: Yeah? So the classical picture of light. Maxwell's idea from 490 00:22:58,520 --> 00:23:01,080 Speaker 2: like one hundred and fifty years ago before quantum mechanics 491 00:23:01,640 --> 00:23:05,000 Speaker 2: is that light just wiggles in the electromagnetic field, like 492 00:23:05,040 --> 00:23:07,520 Speaker 2: an electron has an electric field, right, and if you 493 00:23:07,600 --> 00:23:11,399 Speaker 2: wiggle an electron, the field wiggles with it. That's why 494 00:23:11,480 --> 00:23:15,800 Speaker 2: wiggling electrons in an antenna will generate waves like radio waves, 495 00:23:15,800 --> 00:23:20,680 Speaker 2: which are electromagnetic waves and other charge particles wiggling more 496 00:23:20,760 --> 00:23:25,200 Speaker 2: quickly with higher frequency will generate waves in the electromagnetic 497 00:23:25,240 --> 00:23:28,119 Speaker 2: field that have higher frequency. Some of those are visible 498 00:23:28,200 --> 00:23:32,000 Speaker 2: light or even ultraviolet light. So all kinds of light 499 00:23:32,119 --> 00:23:36,040 Speaker 2: and radio waves, all the electromagnetic radiation are just wiggles 500 00:23:36,080 --> 00:23:38,800 Speaker 2: in the electromagnetic field. That's the classical picture. 501 00:23:39,560 --> 00:23:41,760 Speaker 1: And the electromagnetic field in this case is not the 502 00:23:41,800 --> 00:23:45,679 Speaker 1: same as the electromagnetic quantum field that we've talked about before. 503 00:23:45,880 --> 00:23:47,960 Speaker 2: Well, you can quantize this whole theory, right, You can 504 00:23:47,960 --> 00:23:50,919 Speaker 2: say the electromagnetic field follows rules of quantum mechanics and 505 00:23:50,960 --> 00:23:54,760 Speaker 2: so only some solutions are valid and there's minimum oscillations. 506 00:23:55,160 --> 00:23:58,000 Speaker 2: But in classical physics, it just follows standard wave equations 507 00:23:58,320 --> 00:24:01,200 Speaker 2: and it's just the electromagnetic fields. It's the same field. 508 00:24:01,520 --> 00:24:04,040 Speaker 2: It's just like which equations are using to describe it, 509 00:24:04,080 --> 00:24:06,639 Speaker 2: and are those quant mechanical or not. And here we 510 00:24:06,680 --> 00:24:08,760 Speaker 2: don't need to get into the quant mechanics. But it 511 00:24:08,800 --> 00:24:12,480 Speaker 2: is important to understand what that field is. Right. Sometimes 512 00:24:12,480 --> 00:24:14,800 Speaker 2: we imagine a field is this like weird physical thing 513 00:24:14,840 --> 00:24:17,399 Speaker 2: that fills space, But really what it is is a 514 00:24:17,440 --> 00:24:20,280 Speaker 2: set of numbers at every point in space. Like if 515 00:24:20,280 --> 00:24:22,280 Speaker 2: you think about an electric field. You think, well, it's 516 00:24:22,280 --> 00:24:25,520 Speaker 2: strongest near the electron, it's weaker further from the electron. Right, 517 00:24:25,520 --> 00:24:29,440 Speaker 2: there's values to the field, and those values vary across space. 518 00:24:29,920 --> 00:24:32,360 Speaker 2: That's how you can have a wave propagating through it. 519 00:24:32,359 --> 00:24:34,960 Speaker 2: It's like stronger here and weaker there, and stronger here, 520 00:24:35,200 --> 00:24:37,520 Speaker 2: and those values are moving through the field. 521 00:24:37,440 --> 00:24:39,679 Speaker 1: Sort of, I guess, like a sound wave kind of, 522 00:24:39,720 --> 00:24:42,719 Speaker 1: but instead of there being like a physical air particles, 523 00:24:42,920 --> 00:24:45,200 Speaker 1: imagine they're just being nothing there, just mad. 524 00:24:45,280 --> 00:24:49,240 Speaker 2: Yeah, exactly, just numbers. Imagine those numbers then moving through space, 525 00:24:49,560 --> 00:24:51,679 Speaker 2: Like this location is a zero and the next location 526 00:24:51,800 --> 00:24:54,040 Speaker 2: is a two, and then that two is moving through space, 527 00:24:54,040 --> 00:24:56,440 Speaker 2: and now a different location has that too. That's like 528 00:24:56,480 --> 00:24:58,240 Speaker 2: a pulse moving through a field. 529 00:24:58,440 --> 00:25:00,760 Speaker 1: But is it too moving through space or is it 530 00:25:00,840 --> 00:25:04,640 Speaker 1: too somehow like exciting the number besides it making it 531 00:25:04,640 --> 00:25:06,800 Speaker 1: sort of like the wave in a stadium when you're 532 00:25:06,920 --> 00:25:08,000 Speaker 1: watching a game or something. 533 00:25:08,160 --> 00:25:10,160 Speaker 2: Yeah, it's more like the wave in a stadium. Right. 534 00:25:10,480 --> 00:25:13,040 Speaker 2: The energy is moving from one spot in space to 535 00:25:13,080 --> 00:25:15,600 Speaker 2: another spot in space. It's a different place in the 536 00:25:15,600 --> 00:25:17,560 Speaker 2: field that now has that energy. 537 00:25:17,880 --> 00:25:21,120 Speaker 1: Okay, so then before quantum physics, we thought all light 538 00:25:21,240 --> 00:25:24,240 Speaker 1: is just like the wave in a stadium. It propagates 539 00:25:24,280 --> 00:25:27,000 Speaker 1: that way. And I guess that makes sense for like 540 00:25:27,440 --> 00:25:30,480 Speaker 1: a light bulb, which is emanating light in all directions. 541 00:25:30,600 --> 00:25:32,320 Speaker 1: But then how do you think about it as a 542 00:25:32,400 --> 00:25:34,800 Speaker 1: for a laser. Is it just like one row of 543 00:25:34,840 --> 00:25:36,840 Speaker 1: the stadium is carrying the wave? 544 00:25:37,280 --> 00:25:40,000 Speaker 2: Yeah, just like one row of the stadium exactly. And 545 00:25:40,040 --> 00:25:43,440 Speaker 2: there's an important point here. When you're visualizing that laser beam, 546 00:25:43,480 --> 00:25:46,080 Speaker 2: that photon flying through space, you probably have in your 547 00:25:46,119 --> 00:25:48,400 Speaker 2: mind some sort of like sine wave, like it's wiggling 548 00:25:48,480 --> 00:25:51,720 Speaker 2: sideways as it moves through space, right, So what is 549 00:25:51,760 --> 00:25:54,679 Speaker 2: actually wiggling sideways there? Does the laser actually have like 550 00:25:54,720 --> 00:25:57,760 Speaker 2: a sideways extent? The answer is no. The light moves 551 00:25:57,800 --> 00:26:01,359 Speaker 2: in a straight, perfect line. Make a laser beam that 552 00:26:01,400 --> 00:26:04,520 Speaker 2: has like zero width and is perfectly parallel, then the 553 00:26:04,600 --> 00:26:07,520 Speaker 2: light moves in a narrow line. It doesn't wiggle sideways. 554 00:26:08,119 --> 00:26:11,680 Speaker 2: What's wiggling are the values of the field, right, Because 555 00:26:11,720 --> 00:26:15,480 Speaker 2: electromagnetic fields are slightly more complicated than just numbers in space. 556 00:26:15,880 --> 00:26:19,399 Speaker 2: There are vectors in space. So now at every point 557 00:26:19,440 --> 00:26:21,159 Speaker 2: in the field, you don't just have a number like 558 00:26:21,160 --> 00:26:24,399 Speaker 2: a two. You have a number and a direction and 559 00:26:24,440 --> 00:26:28,119 Speaker 2: so that's what's oscillating. As the light beam moves through space, 560 00:26:28,400 --> 00:26:31,320 Speaker 2: you have like an arrow a vector from that point, 561 00:26:31,359 --> 00:26:34,480 Speaker 2: and that vector can change directions and magnitude. So when 562 00:26:34,480 --> 00:26:38,080 Speaker 2: they depict the photon like wiggling sideways, it's not physically 563 00:26:38,119 --> 00:26:40,560 Speaker 2: moving to other points of space. It's just that the 564 00:26:40,720 --> 00:26:43,560 Speaker 2: arrow of the electro or magnetic field is now pointing 565 00:26:43,600 --> 00:26:44,800 Speaker 2: in a different direction. 566 00:26:44,880 --> 00:26:47,879 Speaker 1: Like its value as a direction sort of perpendicular to 567 00:26:47,960 --> 00:26:51,600 Speaker 1: the direction of the travel. Yeah, exactly is that direction changing? 568 00:26:51,680 --> 00:26:54,160 Speaker 1: Like for a regular pulse of light, That direction doesn't 569 00:26:54,200 --> 00:26:55,040 Speaker 1: really change, does it? 570 00:26:55,119 --> 00:26:57,720 Speaker 2: Absolutely? It does, And that's what the wavelength is, right. 571 00:26:57,920 --> 00:27:01,240 Speaker 2: The wavelength is how far the life light travels before 572 00:27:01,240 --> 00:27:03,320 Speaker 2: the arrow comes back to where it was before. 573 00:27:03,600 --> 00:27:05,920 Speaker 1: Wait, as it's going, as the pulse is going, it's 574 00:27:06,000 --> 00:27:08,560 Speaker 1: changing in both the value and it's rotating. 575 00:27:08,920 --> 00:27:12,760 Speaker 2: That's right, because it's shifting between its electrical and magnetic components. 576 00:27:13,160 --> 00:27:16,119 Speaker 2: At one point, it's purely electrical in one direction, and 577 00:27:16,160 --> 00:27:19,200 Speaker 2: then that electrical component is shrinking as the magnetic component 578 00:27:19,320 --> 00:27:22,720 Speaker 2: is growing in a perpendicular direction. Those two fields are 579 00:27:22,720 --> 00:27:25,520 Speaker 2: always perpendicular to each other. Which direction does it rotate? 580 00:27:25,640 --> 00:27:28,479 Speaker 2: That depends on the polarization of the light. Light can 581 00:27:28,520 --> 00:27:30,480 Speaker 2: be polarized in lots of different directions, so it could 582 00:27:30,520 --> 00:27:32,760 Speaker 2: not rotate, or it could rotate left, or it could 583 00:27:32,800 --> 00:27:35,360 Speaker 2: rotate right. That's a whole other issue. We talked about 584 00:27:35,400 --> 00:27:38,120 Speaker 2: that in another podcast, the polarization of light. But here 585 00:27:38,160 --> 00:27:41,520 Speaker 2: we can just imagine the simplest scenario. Imagine it's not polarized. 586 00:27:41,720 --> 00:27:44,280 Speaker 2: The electric field is pointing in one direction, then it 587 00:27:44,359 --> 00:27:46,800 Speaker 2: shrinks to zero as the magnetic field is created. Then 588 00:27:46,840 --> 00:27:49,000 Speaker 2: it goes negative, so it points in the opposite direction, 589 00:27:49,280 --> 00:27:51,480 Speaker 2: and then it comes back. The wavelength of the light 590 00:27:51,520 --> 00:27:54,280 Speaker 2: is how far it's traveled between those peaks of the 591 00:27:54,359 --> 00:27:55,440 Speaker 2: electric field. 592 00:27:55,280 --> 00:27:58,400 Speaker 1: All right. So then John's question was like, what does 593 00:27:58,440 --> 00:28:02,280 Speaker 1: it mean to have a nanometer wavelength and wavelength that's 594 00:28:02,320 --> 00:28:05,639 Speaker 1: maybe tens of meters long. Does that mean like the 595 00:28:05,680 --> 00:28:06,639 Speaker 1: wiggles are just shorter. 596 00:28:06,840 --> 00:28:08,919 Speaker 2: Yeah, it just means the wiggles are shorter. So if 597 00:28:09,000 --> 00:28:13,080 Speaker 2: you generate microwave radiation, you know, with microwave wavelength, that 598 00:28:13,160 --> 00:28:16,040 Speaker 2: means like the light travels a very short distance between 599 00:28:16,040 --> 00:28:18,600 Speaker 2: those peaks and the electric field. If it's like radio 600 00:28:18,680 --> 00:28:22,080 Speaker 2: waves with tens of meters of wavelength, then it means 601 00:28:22,080 --> 00:28:24,200 Speaker 2: that You can start off with like your electric field 602 00:28:24,240 --> 00:28:26,479 Speaker 2: peaking at one place, and then it's literally tens of 603 00:28:26,520 --> 00:28:29,720 Speaker 2: meters before it osclates down and then back so that 604 00:28:29,760 --> 00:28:32,280 Speaker 2: it has the electric field pointing in the same direction. Again, 605 00:28:32,800 --> 00:28:34,160 Speaker 2: that really is something physical. 606 00:28:35,000 --> 00:28:37,120 Speaker 1: But in both cases it's going at the speed of light. 607 00:28:37,240 --> 00:28:39,360 Speaker 1: It's going at the same speed. Is just that's right, 608 00:28:39,960 --> 00:28:44,640 Speaker 1: Spiraling or wiggling or changing at a different scale. 609 00:28:44,160 --> 00:28:46,880 Speaker 2: That's right. The frequency is different, but the overall speed 610 00:28:46,920 --> 00:28:48,920 Speaker 2: of the wave is the same. It's still moving at 611 00:28:48,960 --> 00:28:51,520 Speaker 2: the speed of light. Just how many wavelengths happen when 612 00:28:51,560 --> 00:28:52,680 Speaker 2: you go one hundred meters. 613 00:28:54,440 --> 00:28:56,480 Speaker 1: But again, I feel like this is kind of the 614 00:28:56,560 --> 00:28:59,719 Speaker 1: classical view. You preface this as being the classical view. 615 00:28:59,840 --> 00:29:02,400 Speaker 1: Is this actually what's going on? And does this actually 616 00:29:02,440 --> 00:29:04,719 Speaker 1: tell us what light is? Or is this just some 617 00:29:04,840 --> 00:29:08,600 Speaker 1: mathematics that we came up with that helps explain what's 618 00:29:08,640 --> 00:29:09,680 Speaker 1: going on with life? 619 00:29:10,160 --> 00:29:12,440 Speaker 2: You know, some mathematics that we came up with that 620 00:29:12,480 --> 00:29:15,400 Speaker 2: helps explain what we see, could describe all the physics. 621 00:29:15,640 --> 00:29:17,959 Speaker 2: You know, we don't know what's really going on at 622 00:29:18,000 --> 00:29:21,480 Speaker 2: any level philosophically. All of our theories are just some 623 00:29:21,640 --> 00:29:23,960 Speaker 2: mathematics that help us explain what's going on. We don't 624 00:29:24,000 --> 00:29:26,120 Speaker 2: know what's true. We think that none of our theories 625 00:29:26,160 --> 00:29:26,480 Speaker 2: are true. 626 00:29:26,560 --> 00:29:28,240 Speaker 1: Well, there's a little bit of a difference, right, Like 627 00:29:28,240 --> 00:29:31,000 Speaker 1: for example, like if you're dealing with waves in the ocean, 628 00:29:31,040 --> 00:29:33,720 Speaker 1: you can use wave equations describe those ways, but really 629 00:29:33,720 --> 00:29:36,440 Speaker 1: you know that underneath there's you know, little particles of 630 00:29:36,520 --> 00:29:41,320 Speaker 1: water bumping against each other and propagating energy and pulling 631 00:29:41,320 --> 00:29:44,000 Speaker 1: on each other. Right, So it's like the wave equations 632 00:29:44,040 --> 00:29:46,240 Speaker 1: work and they start tell you what's going on, but 633 00:29:46,360 --> 00:29:48,440 Speaker 1: they maybe don't tell you about the nature of what's 634 00:29:48,520 --> 00:29:49,480 Speaker 1: going on underneath. 635 00:29:49,520 --> 00:29:52,360 Speaker 2: That's right, but sometimes they're actually better at answering questions. 636 00:29:52,640 --> 00:29:55,560 Speaker 2: Depends on the question you're asking. If you're asking questions 637 00:29:55,560 --> 00:29:58,160 Speaker 2: about waves and why they reflect or why they break, 638 00:29:58,320 --> 00:30:00,600 Speaker 2: then the answer is better described in terms of the 639 00:30:00,640 --> 00:30:03,680 Speaker 2: macroscopic why the waves break. It's because as they approach 640 00:30:03,760 --> 00:30:06,080 Speaker 2: the shore, part of them get dragged. You can't really 641 00:30:06,120 --> 00:30:09,280 Speaker 2: answer that question using the microscopic picture of waves as 642 00:30:09,320 --> 00:30:12,000 Speaker 2: tiny particles. You get lost in the details. So the 643 00:30:12,040 --> 00:30:14,360 Speaker 2: answer depends on the question you're asking. Which theory of 644 00:30:14,360 --> 00:30:17,600 Speaker 2: physics you want to use, which approximation, which details you 645 00:30:17,600 --> 00:30:19,520 Speaker 2: want to sweep under the rug depends on the question 646 00:30:19,640 --> 00:30:23,320 Speaker 2: you're asking, because fundamentally we don't know the deepest theory 647 00:30:23,360 --> 00:30:25,400 Speaker 2: of the universe, So in that sense, we can't answer 648 00:30:25,480 --> 00:30:27,400 Speaker 2: any questions. We always got to zoom out to some 649 00:30:27,600 --> 00:30:30,440 Speaker 2: level and give the appropriate answer based on the question. 650 00:30:30,600 --> 00:30:32,800 Speaker 1: Right right. But I feel like John's question here is 651 00:30:32,840 --> 00:30:34,800 Speaker 1: trying to get us to like, what is the nature 652 00:30:34,800 --> 00:30:37,560 Speaker 1: of things? Right? Like, I feel like we've just repeated 653 00:30:37,560 --> 00:30:40,240 Speaker 1: his question thus far, which is like, yeah, life has 654 00:30:40,240 --> 00:30:42,440 Speaker 1: different wavelengths, and some of them are shorter, some of 655 00:30:42,480 --> 00:30:45,040 Speaker 1: them are longer. Like, then what would you say then, 656 00:30:45,560 --> 00:30:51,360 Speaker 1: is the relationship between these oscillating electromagnetic fields and arrows 657 00:30:51,560 --> 00:30:55,720 Speaker 1: and maybe what we know now about the quantum particle 658 00:30:55,800 --> 00:30:56,440 Speaker 1: nature of things? 659 00:30:56,520 --> 00:30:58,240 Speaker 2: I mean, I think maybe you're more curious about the 660 00:30:58,280 --> 00:31:01,040 Speaker 2: quantum nature John wanted to know about micro wave But 661 00:31:01,160 --> 00:31:03,720 Speaker 2: you know, in terms of the quantum nature, quantum theory 662 00:31:03,760 --> 00:31:08,360 Speaker 2: of electrodynamics is a natural successor of classical electrodynamics. Like 663 00:31:08,400 --> 00:31:12,000 Speaker 2: you take Maxiwell's equations for electromagnetic fields and you quantize them. 664 00:31:12,000 --> 00:31:14,160 Speaker 2: You say, well, they can't just have any value, they 665 00:31:14,200 --> 00:31:16,840 Speaker 2: have to have limited values, And you end up with 666 00:31:16,880 --> 00:31:20,600 Speaker 2: photons packets minimum bundles of energy in the field instead 667 00:31:20,600 --> 00:31:23,959 Speaker 2: of arbitrary size energies. In classical theory, you can have 668 00:31:24,320 --> 00:31:27,840 Speaker 2: as dim light as you want, but in quantum theory 669 00:31:27,880 --> 00:31:31,120 Speaker 2: you can't. There's a minimum there. It's because there's additional mathematics. 670 00:31:31,400 --> 00:31:34,360 Speaker 2: So there's definitely a relationship between like the wave function 671 00:31:34,560 --> 00:31:38,040 Speaker 2: of a photon and the classical wave length of a 672 00:31:38,040 --> 00:31:40,080 Speaker 2: beam of light. And we're actually going to talk about 673 00:31:40,080 --> 00:31:42,160 Speaker 2: that in an episode coming up soon where we talk 674 00:31:42,160 --> 00:31:45,320 Speaker 2: about like how long is a photon? But I think 675 00:31:45,360 --> 00:31:48,240 Speaker 2: to answer John's question here about like why can mesh 676 00:31:48,240 --> 00:31:52,720 Speaker 2: holes block microwaves, we only need to use classical physics. 677 00:31:52,320 --> 00:31:54,560 Speaker 1: All right, Well, let's answer that question then, because he 678 00:31:54,560 --> 00:31:57,240 Speaker 1: asked that directly, like why is it that some waves 679 00:31:57,240 --> 00:31:58,600 Speaker 1: can pass through holes and others not? 680 00:31:58,960 --> 00:32:01,080 Speaker 2: This is a really cool ques question, and actually a 681 00:32:01,160 --> 00:32:03,840 Speaker 2: very difficult one. A simpler version of the question is 682 00:32:03,920 --> 00:32:07,000 Speaker 2: much more simple, like why does a metal box at 683 00:32:07,040 --> 00:32:10,400 Speaker 2: all block radiation? The microwave is encased in a metal 684 00:32:10,400 --> 00:32:12,720 Speaker 2: box to protect you from the radiation, but you might wonder, 685 00:32:12,760 --> 00:32:15,760 Speaker 2: like how do the metal box block radiation? Like when 686 00:32:15,760 --> 00:32:18,160 Speaker 2: you get into an elevator, why you have no cell 687 00:32:18,200 --> 00:32:20,960 Speaker 2: phone signal. It's the same question. And this is a 688 00:32:20,960 --> 00:32:24,640 Speaker 2: simple process called a Faraday cage. Anything that's a conductor 689 00:32:24,920 --> 00:32:27,440 Speaker 2: that has electrons roaming around in it. If you try 690 00:32:27,480 --> 00:32:31,120 Speaker 2: to pass an electrical signal through that conductor, the electrons 691 00:32:31,240 --> 00:32:34,880 Speaker 2: inside the conductor are going to rearrange themselves to basically 692 00:32:34,920 --> 00:32:39,000 Speaker 2: cancel out that electromagnetic radiation. Because there are electrons free 693 00:32:39,040 --> 00:32:42,880 Speaker 2: to move. The radiation creates electric fields that pushes the 694 00:32:42,920 --> 00:32:47,400 Speaker 2: electrons to counteract that electric field. So you basically can't 695 00:32:47,400 --> 00:32:50,640 Speaker 2: have an electric field inside a conductor. And so you 696 00:32:50,640 --> 00:32:52,440 Speaker 2: build a metal box. You can put your phone inside, 697 00:32:52,440 --> 00:32:55,200 Speaker 2: for example, it'll get no signal and also nobody can 698 00:32:55,200 --> 00:32:58,040 Speaker 2: spy on you. So that's how a Faraday cage works 699 00:32:58,120 --> 00:33:00,640 Speaker 2: if it has no holes in it. 700 00:33:00,120 --> 00:33:03,160 Speaker 1: Because the box, i guess, is made out of stuff, 701 00:33:03,200 --> 00:33:05,320 Speaker 1: and that stuff blocks the light trying to get in. 702 00:33:05,600 --> 00:33:08,360 Speaker 2: Yeah, exactly. And it's not just that it blocks light, right, 703 00:33:08,400 --> 00:33:11,000 Speaker 2: you know, materials can block light, but metal can also 704 00:33:11,040 --> 00:33:14,719 Speaker 2: block invisible radio waves that could pass through walls, they 705 00:33:14,800 --> 00:33:16,120 Speaker 2: just can't pass through metal. 706 00:33:16,240 --> 00:33:20,320 Speaker 1: So for a given metal box, there's no wave of 707 00:33:20,440 --> 00:33:21,640 Speaker 1: light that can penetrate it. 708 00:33:21,640 --> 00:33:24,400 Speaker 2: It depends on the wavelength and the thickness of the box, 709 00:33:24,480 --> 00:33:28,280 Speaker 2: Like there is a depth that electromagnetic radiation can penetrate 710 00:33:28,560 --> 00:33:32,080 Speaker 2: into various conductors. So like a super high intensity beam 711 00:33:32,200 --> 00:33:35,040 Speaker 2: or the right wavelength might be able to penetrate some 712 00:33:35,240 --> 00:33:39,480 Speaker 2: metal boxes depending on their thickness. But for a perfect conductor, 713 00:33:39,560 --> 00:33:42,520 Speaker 2: then yes, you have to have zero electromagnetic field inside 714 00:33:42,520 --> 00:33:42,720 Speaker 2: of it. 715 00:33:43,240 --> 00:33:45,840 Speaker 1: Okay, So then what happens in like in my microwave 716 00:33:45,840 --> 00:33:47,960 Speaker 1: that if you punch holes in this box? 717 00:33:48,040 --> 00:33:50,120 Speaker 2: Yeah, so you might wonder, Okay, there's holes in the box. 718 00:33:50,440 --> 00:33:52,719 Speaker 2: Why can't like go through the holes and be blocked 719 00:33:52,760 --> 00:33:53,400 Speaker 2: by the mesh? 720 00:33:53,840 --> 00:33:53,920 Speaker 3: Right? 721 00:33:54,000 --> 00:33:57,800 Speaker 2: Am I just getting like patchy radiation through the holes? Amazingly, 722 00:33:57,880 --> 00:34:00,840 Speaker 2: You're not. Even though there are holes in that none 723 00:34:00,880 --> 00:34:01,960 Speaker 2: of the light gets through. 724 00:34:02,200 --> 00:34:04,080 Speaker 1: Well, some light gets through, because I can see inside 725 00:34:04,080 --> 00:34:05,160 Speaker 1: my microwave. 726 00:34:04,760 --> 00:34:06,800 Speaker 2: That's right. None of the microwaves get through. The light 727 00:34:06,840 --> 00:34:09,120 Speaker 2: actually does get through. And so now it depends on 728 00:34:09,239 --> 00:34:12,640 Speaker 2: the frequency of the light. And I think in John's question, 729 00:34:12,719 --> 00:34:15,480 Speaker 2: he's wondering, like, is that because the light is like 730 00:34:15,560 --> 00:34:18,960 Speaker 2: oscillating sideways and so it can't fit through the mesh. 731 00:34:19,040 --> 00:34:21,080 Speaker 2: And the answer to that is no, that's misleading, right, 732 00:34:21,160 --> 00:34:24,800 Speaker 2: light is not oscillating sideways. Microwaves or visible light in 733 00:34:25,120 --> 00:34:27,359 Speaker 2: right through the center of one of those holes. They 734 00:34:27,360 --> 00:34:30,000 Speaker 2: can both fit through the hole. It's not a physical issue. 735 00:34:30,040 --> 00:34:32,600 Speaker 2: They're not like bumping up against the size of the hole. 736 00:34:32,960 --> 00:34:36,200 Speaker 2: It's a different effect. That's filtering out the microwaves and 737 00:34:36,280 --> 00:34:37,160 Speaker 2: not the visible light. 738 00:34:37,280 --> 00:34:38,360 Speaker 1: So then what is that effect? 739 00:34:38,440 --> 00:34:39,880 Speaker 2: Yeah, so what's going on there is a little bit 740 00:34:39,880 --> 00:34:42,160 Speaker 2: more subtle. What has to happen is you have to 741 00:34:42,200 --> 00:34:45,319 Speaker 2: have zero electric field inside the mesh. Like everywhere you 742 00:34:45,360 --> 00:34:48,120 Speaker 2: have metal, you have conductor, you have electrons. That's going 743 00:34:48,160 --> 00:34:50,440 Speaker 2: to zero out the field. Now you need to think 744 00:34:50,480 --> 00:34:52,359 Speaker 2: of the light not as a particle, not like as 745 00:34:52,400 --> 00:34:54,839 Speaker 2: one little thing that's like a tennis ball flying through 746 00:34:54,840 --> 00:34:57,479 Speaker 2: the hole, but like a wave. And when a wave 747 00:34:57,560 --> 00:35:00,120 Speaker 2: meets a new kind of material, like when light it 748 00:35:00,200 --> 00:35:02,960 Speaker 2: hits glass or when light hits water, right, then you 749 00:35:03,040 --> 00:35:05,319 Speaker 2: have to find a solution that satisfies all the wave 750 00:35:05,320 --> 00:35:08,799 Speaker 2: equations at the boundaries. What that really means is that 751 00:35:08,840 --> 00:35:11,759 Speaker 2: the waves have to line up. Remember we talked about 752 00:35:11,800 --> 00:35:14,520 Speaker 2: the waves as wiggles in the field. Well, you can't 753 00:35:14,560 --> 00:35:17,840 Speaker 2: have weird discontinuities in the field. They have to match 754 00:35:17,920 --> 00:35:20,879 Speaker 2: up at that boundary. This is why, for example, light 755 00:35:21,040 --> 00:35:23,760 Speaker 2: bends when it goes from air to glass or water, 756 00:35:23,880 --> 00:35:27,520 Speaker 2: because the different medium means a different index of refraction, 757 00:35:27,640 --> 00:35:30,799 Speaker 2: which means a different wavelength. So for two fields to 758 00:35:30,880 --> 00:35:33,880 Speaker 2: match at the boundary when they have a different wavelength, 759 00:35:34,239 --> 00:35:36,440 Speaker 2: one of them has to be bent relative to the 760 00:35:36,480 --> 00:35:39,840 Speaker 2: other at a different angle. The same principle applies here 761 00:35:40,080 --> 00:35:42,800 Speaker 2: with the case of the mesh, but it's much harder 762 00:35:42,840 --> 00:35:46,040 Speaker 2: to find solutions on both sides of the mesh because 763 00:35:46,080 --> 00:35:48,880 Speaker 2: the mesh requires the field to be zero at so 764 00:35:49,120 --> 00:35:52,120 Speaker 2: many places on it, and in this case, requiring that 765 00:35:52,160 --> 00:35:56,200 Speaker 2: the electromagnetic field is zero inside the mesh creates these 766 00:35:56,239 --> 00:36:00,680 Speaker 2: interference effects that can slowt any electromagnetic fields below a 767 00:36:00,719 --> 00:36:02,840 Speaker 2: certain wavelength on the other side of the mesh. 768 00:36:03,120 --> 00:36:05,279 Speaker 1: Okay, you lost me a little bit there. I wonder 769 00:36:05,280 --> 00:36:08,359 Speaker 1: if we've lost our listeners. So maybe maybe a more 770 00:36:08,400 --> 00:36:11,040 Speaker 1: simple scenario. Let's say I'm a markwave and I'm flying 771 00:36:11,080 --> 00:36:14,120 Speaker 1: through space and I see a big metal sheet in 772 00:36:14,160 --> 00:36:15,719 Speaker 1: front of me with a little tiny hole in it. 773 00:36:16,120 --> 00:36:18,040 Speaker 1: Now earlier saying that I should be able to go 774 00:36:18,120 --> 00:36:20,279 Speaker 1: through it because I don't really have any width to 775 00:36:20,400 --> 00:36:23,640 Speaker 1: me right like, the wavelength of my light is not 776 00:36:24,719 --> 00:36:29,840 Speaker 1: sideways to me. It's more like how often I'm pulsing? 777 00:36:30,040 --> 00:36:32,439 Speaker 1: Right A, Technically I could still go through that hole. 778 00:36:33,040 --> 00:36:34,359 Speaker 2: You have no width to you. 779 00:36:34,480 --> 00:36:37,760 Speaker 1: Yes, yeah, I'm a beam of light. If I'm a microwave, 780 00:36:37,800 --> 00:36:39,480 Speaker 1: why can't I go through that little hole? 781 00:36:39,600 --> 00:36:41,560 Speaker 2: Yeah, it sounds like you should be able to. But 782 00:36:41,640 --> 00:36:43,960 Speaker 2: you're actually using a particle picture, right. You're thinking of 783 00:36:44,000 --> 00:36:48,040 Speaker 2: yourself as having one location and flying through space, But 784 00:36:48,080 --> 00:36:51,080 Speaker 2: we're talking about waves, and waves have to have solutions 785 00:36:51,160 --> 00:36:54,040 Speaker 2: everywhere in space. So you have to find a solution 786 00:36:54,160 --> 00:36:57,160 Speaker 2: that satisfies all the equations everywhere in space. It's not 787 00:36:57,160 --> 00:36:59,880 Speaker 2: about an individual particle flying through space. It's like a 788 00:37:00,000 --> 00:37:02,759 Speaker 2: steady state. You have like waves in this box and 789 00:37:02,800 --> 00:37:04,880 Speaker 2: they're bouncing around. Can any of them escape? 790 00:37:05,400 --> 00:37:08,040 Speaker 1: Didn't we talk about like a single beam of light 791 00:37:08,120 --> 00:37:11,799 Speaker 1: being like one row in a stadium that's doing the 792 00:37:11,840 --> 00:37:15,000 Speaker 1: wave like it's super thin. Couldn't that wave go through 793 00:37:15,040 --> 00:37:15,600 Speaker 1: a little hole? 794 00:37:15,800 --> 00:37:17,319 Speaker 2: Yeah, it's one row, But you have to think about 795 00:37:17,360 --> 00:37:19,239 Speaker 2: the whole row, right, You have to think about the 796 00:37:19,239 --> 00:37:21,520 Speaker 2: equations of the whole row and the wather. The equations 797 00:37:21,520 --> 00:37:23,239 Speaker 2: work on one side of the mesh and the other 798 00:37:23,320 --> 00:37:26,400 Speaker 2: side of the mesh. It's a little bit unsatisfactory because 799 00:37:26,400 --> 00:37:30,000 Speaker 2: it's all about these interference terms, satisfying the equations. It's 800 00:37:30,000 --> 00:37:32,600 Speaker 2: hard to get a physical intuition on it. The best 801 00:37:32,600 --> 00:37:34,759 Speaker 2: I can do is to remind you that when you 802 00:37:34,840 --> 00:37:38,560 Speaker 2: approach that mesh, you're not just flying through it, right, 803 00:37:38,600 --> 00:37:41,319 Speaker 2: You're inducing electromagnetic fields in nearby and so you need 804 00:37:41,320 --> 00:37:44,200 Speaker 2: a solution on both sides, and that effectively induces light 805 00:37:44,239 --> 00:37:48,440 Speaker 2: in lots of different directions. And there's the requirement that 806 00:37:48,480 --> 00:37:51,200 Speaker 2: the electric field be zero inside the mesh, means that 807 00:37:51,239 --> 00:37:54,680 Speaker 2: you can't have wavelengths that are longer than that because 808 00:37:54,680 --> 00:37:57,680 Speaker 2: it will hit that zero requirement and get canceled out. 809 00:37:58,000 --> 00:38:00,439 Speaker 2: This is the same issue with like thinking about how 810 00:38:00,600 --> 00:38:02,680 Speaker 2: like it's bent at an interface, Like, how does that 811 00:38:02,719 --> 00:38:05,480 Speaker 2: actually happen? How does an individual photon get bent? How 812 00:38:05,520 --> 00:38:08,520 Speaker 2: all the photons bent the same way? It's the photon 813 00:38:08,560 --> 00:38:11,480 Speaker 2: picture that's the problem. Is really there's a wave description here, 814 00:38:11,920 --> 00:38:14,480 Speaker 2: and it's the solutions to the wave equations that dictate 815 00:38:14,520 --> 00:38:17,360 Speaker 2: what happens. So the problem is thinking about it in 816 00:38:17,440 --> 00:38:19,880 Speaker 2: terms of like a little particle flying through. 817 00:38:19,960 --> 00:38:22,719 Speaker 1: You're right, that is a very unsatisfied. It's hard to 818 00:38:22,760 --> 00:38:25,120 Speaker 1: tackle in a podcast, but I think what you're saying 819 00:38:25,239 --> 00:38:28,400 Speaker 1: is that instead of thinking about this in a time 820 00:38:28,840 --> 00:38:31,480 Speaker 1: sequential way, like I'm in one side of the wall 821 00:38:31,480 --> 00:38:33,840 Speaker 1: with a hole in it, and then later I'm on 822 00:38:33,880 --> 00:38:35,560 Speaker 1: the other side of the wall with the hole in it. 823 00:38:36,239 --> 00:38:38,000 Speaker 1: You because you're talking about waves, you kind of have 824 00:38:38,000 --> 00:38:39,960 Speaker 1: to think about it all at the same time, Like 825 00:38:40,000 --> 00:38:42,319 Speaker 1: the before and the after all had to be part 826 00:38:42,360 --> 00:38:47,520 Speaker 1: of the same physical consistency. And somehow if my wavelength 827 00:38:47,560 --> 00:38:50,200 Speaker 1: is too big, I just can't go through that hole, 828 00:38:50,239 --> 00:38:52,840 Speaker 1: Like there's no solution that puts me in both sides 829 00:38:52,840 --> 00:38:55,040 Speaker 1: of the hole in the timeline of the universe. 830 00:38:55,120 --> 00:38:57,719 Speaker 2: Yeah, exactly. And you can actually escape this requirement a 831 00:38:57,719 --> 00:39:00,360 Speaker 2: tiny bit if you send little pulses, Like if you 832 00:39:00,400 --> 00:39:03,920 Speaker 2: said individual tiny little pulses are microwaves, some of them 833 00:39:03,960 --> 00:39:06,400 Speaker 2: will get through, but it's when you have a consistent 834 00:39:06,520 --> 00:39:08,960 Speaker 2: source of the microwaves. It's like the previous ones are 835 00:39:09,000 --> 00:39:11,480 Speaker 2: canceling out the future ones, and they're all interfering with 836 00:39:11,560 --> 00:39:14,480 Speaker 2: each other in just the right way to cancel any 837 00:39:14,520 --> 00:39:18,200 Speaker 2: waves that make it through. Individual pulses actually can get 838 00:39:18,200 --> 00:39:20,560 Speaker 2: through a little bit, so you're exactly right. You have 839 00:39:20,600 --> 00:39:22,719 Speaker 2: to think about, like the steady state solution, all the 840 00:39:22,800 --> 00:39:25,799 Speaker 2: waves working together, can any of them make it through? 841 00:39:26,120 --> 00:39:27,840 Speaker 2: So it's really it's an interference. 842 00:39:27,400 --> 00:39:29,880 Speaker 1: Effect, like the before and the after at the same time. 843 00:39:30,360 --> 00:39:32,360 Speaker 1: So I think to answer John's question, I mean he 844 00:39:32,440 --> 00:39:34,920 Speaker 1: is asking, I think about the physical reality of wavelength 845 00:39:35,000 --> 00:39:37,759 Speaker 1: and what's really the nature of these things. Maybe the 846 00:39:37,800 --> 00:39:40,760 Speaker 1: answer is that the you know, light has this wave nature, 847 00:39:40,760 --> 00:39:43,880 Speaker 1: and this wave nature is not just in space, it's 848 00:39:43,920 --> 00:39:47,120 Speaker 1: also in time. And so for whatever reason, the nature 849 00:39:47,120 --> 00:39:49,160 Speaker 1: of light means that you have to take into account 850 00:39:49,160 --> 00:39:51,200 Speaker 1: the path and the future all at the same time, 851 00:39:51,400 --> 00:39:53,520 Speaker 1: and it all has to work together with the effects 852 00:39:53,560 --> 00:39:57,120 Speaker 1: of the electromagnetic interactions with the wall exactly. 853 00:39:57,440 --> 00:40:00,239 Speaker 2: And this wave picture of light really can't explain all 854 00:40:00,280 --> 00:40:03,439 Speaker 2: these kinds of effects. Light bouncing off of water, light 855 00:40:03,480 --> 00:40:07,160 Speaker 2: refracting in water, and also light being trapped by Faraday cages. 856 00:40:08,360 --> 00:40:10,239 Speaker 1: Well, I feel like it's a bit of an unsatisfied 857 00:40:10,239 --> 00:40:10,839 Speaker 1: answer for John. 858 00:40:10,840 --> 00:40:10,960 Speaker 2: Here. 859 00:40:11,000 --> 00:40:12,719 Speaker 1: Basically the answer is because you can't. 860 00:40:14,520 --> 00:40:16,960 Speaker 2: The answer is that, like the mental picture of light 861 00:40:17,160 --> 00:40:19,799 Speaker 2: moving as a little particle isn't really the right way 862 00:40:19,800 --> 00:40:23,520 Speaker 2: to think about this problem. And unfortunately you need different 863 00:40:23,560 --> 00:40:26,880 Speaker 2: mental models to solve different problems. There's no single unifying 864 00:40:26,960 --> 00:40:29,400 Speaker 2: understanding of physics that we can use in every situation. 865 00:40:29,800 --> 00:40:32,400 Speaker 1: All right, well, thank you John for that question. Now 866 00:40:32,480 --> 00:40:34,759 Speaker 1: let's get to our last question of the day, and 867 00:40:34,800 --> 00:40:38,719 Speaker 1: this one is about quasi particles and crossword puzzles. So 868 00:40:38,800 --> 00:40:41,480 Speaker 1: let's dig into that, but first let's take another quick break. 869 00:40:53,880 --> 00:40:56,120 Speaker 1: All right, we're answering questions here today, and our last 870 00:40:56,160 --> 00:40:57,920 Speaker 1: question comes from Peter. 871 00:40:58,480 --> 00:41:02,839 Speaker 5: Hi, Daniel and Jorge from Winchester, Massachusetts. My question comes 872 00:41:02,840 --> 00:41:06,760 Speaker 5: from a crossword puzzle. The clue was type of quasi 873 00:41:06,800 --> 00:41:10,120 Speaker 5: particle and had to be seven letters. The answer turned 874 00:41:10,120 --> 00:41:13,120 Speaker 5: out to be plasmon p L A S M O N. 875 00:41:13,560 --> 00:41:14,759 Speaker 5: Could you explain what that is? 876 00:41:15,040 --> 00:41:15,360 Speaker 2: Thank you? 877 00:41:16,200 --> 00:41:20,400 Speaker 1: All right, interesting questions here. Peter was doing a crossword 878 00:41:20,440 --> 00:41:24,640 Speaker 1: puzzle and he came across an interesting solution, which is 879 00:41:24,840 --> 00:41:33,000 Speaker 1: a plasmon, and so he's wondering what is that? Or 880 00:41:33,040 --> 00:41:35,680 Speaker 1: maybe Peter just made a mistake on his crossword puzzle. 881 00:41:36,080 --> 00:41:37,960 Speaker 2: No, I think he's exactly right. A plasmon is a 882 00:41:38,040 --> 00:41:41,400 Speaker 2: quaniti particle and it has seven letters. So boom boom boom. 883 00:41:41,480 --> 00:41:43,880 Speaker 1: Oh all right, well, I would have to look at 884 00:41:43,880 --> 00:41:47,760 Speaker 1: the whole crossword puzzle to double check that answer. Sometimes 885 00:41:47,760 --> 00:41:49,680 Speaker 1: crossword puzzles have multiple answers. 886 00:41:49,760 --> 00:41:52,600 Speaker 2: Hmm, that's true. Yeah, there might be many quasi particles 887 00:41:52,600 --> 00:41:53,319 Speaker 2: that satisfy this. 888 00:41:53,960 --> 00:41:56,640 Speaker 1: Yeah. No, they actually designed I think they even call 889 00:41:56,719 --> 00:42:01,040 Speaker 1: them like quantum crossword puzzles where there's like multiple solutions 890 00:42:01,040 --> 00:42:01,879 Speaker 1: that can fit. 891 00:42:02,080 --> 00:42:06,040 Speaker 2: Oh my gosh, like crosswands interfering crosswands. Yeah. 892 00:42:06,160 --> 00:42:09,359 Speaker 1: Yeah, and they have wavelengths and time moves slower. That's 893 00:42:09,400 --> 00:42:14,160 Speaker 1: the whole thing. All right, Well, it sounds like plasmon 894 00:42:14,320 --> 00:42:16,440 Speaker 1: is a real thing. What is it, Daniel, And just 895 00:42:16,480 --> 00:42:21,400 Speaker 1: to spell it out, Peter spells it out, plasmmm. 896 00:42:22,280 --> 00:42:26,719 Speaker 2: A plasmon is a quasi particle. It's like an oscillation 897 00:42:27,160 --> 00:42:32,040 Speaker 2: in plasmas that we can describe using the mathematics of particles. 898 00:42:32,400 --> 00:42:36,319 Speaker 2: Usually when we talk about particles, we're talking about oscillations 899 00:42:36,360 --> 00:42:40,319 Speaker 2: in fields like the electromagnetic field or an electron is 900 00:42:40,320 --> 00:42:44,000 Speaker 2: the oscillation in the electron field, and we have wave 901 00:42:44,040 --> 00:42:47,719 Speaker 2: equations to describe how those fields oscillate and how they vibrate, 902 00:42:48,239 --> 00:42:50,799 Speaker 2: and how the Higgs boson affects them to give them 903 00:42:50,840 --> 00:42:52,640 Speaker 2: mass and all that kind of stuff. You can imagine 904 00:42:52,680 --> 00:42:56,120 Speaker 2: like a little standing wave in the electron field. That's 905 00:42:56,160 --> 00:42:59,080 Speaker 2: what an electron is. So when we talk about particles, 906 00:42:59,120 --> 00:43:03,760 Speaker 2: we have math. It describes the oscillation of these fundamental fields. 907 00:43:03,800 --> 00:43:06,040 Speaker 2: We don't know what these fields are, what really is 908 00:43:06,080 --> 00:43:09,080 Speaker 2: doing the oscillating. That's the math we have. We can 909 00:43:09,120 --> 00:43:11,719 Speaker 2: take that same mathematics and we can apply it to 910 00:43:11,800 --> 00:43:14,760 Speaker 2: things that are not fundamental fields, like you can apply 911 00:43:14,800 --> 00:43:17,920 Speaker 2: it to sound waves in air, or you can apply 912 00:43:18,000 --> 00:43:21,400 Speaker 2: it to electrons moving through materials. You can apply in 913 00:43:21,480 --> 00:43:25,960 Speaker 2: lots of situations, and those are quasi particles. So particles 914 00:43:26,040 --> 00:43:30,040 Speaker 2: are these particular kinds of oscillations in fundamental fields. Quasi 915 00:43:30,040 --> 00:43:32,680 Speaker 2: particles are the same kind of mathematics, the same kind 916 00:43:32,680 --> 00:43:36,040 Speaker 2: of oscillations, but in something that isn't a fundamental field. 917 00:43:36,640 --> 00:43:39,279 Speaker 1: But then you can apply that to real things that 918 00:43:39,320 --> 00:43:42,759 Speaker 1: are made out of things like water and air. Right, 919 00:43:42,920 --> 00:43:46,640 Speaker 1: you can sort of apply those wave functions to media. 920 00:43:46,760 --> 00:43:49,880 Speaker 2: Yeah, exactly. And the cool thing about a particle is 921 00:43:49,920 --> 00:43:52,680 Speaker 2: that it's persistent, right, It's that quantized. You can count it. 922 00:43:52,680 --> 00:43:56,200 Speaker 2: It's discrete, and it like moves through the universe. An 923 00:43:56,200 --> 00:43:58,719 Speaker 2: electron as it moves to the universe, doesn't like dissipate 924 00:43:58,800 --> 00:44:02,840 Speaker 2: down into little many electron ripples. Right. It's persistent in 925 00:44:02,880 --> 00:44:05,359 Speaker 2: this way, and so sometimes you can see the same 926 00:44:05,360 --> 00:44:08,359 Speaker 2: thing happening in other media, right, Like if you can 927 00:44:08,400 --> 00:44:10,840 Speaker 2: make a smoke ring that's really persistent, right, it like 928 00:44:10,880 --> 00:44:13,719 Speaker 2: flows to the universe and holds itself together somehow. I mean, 929 00:44:14,040 --> 00:44:16,160 Speaker 2: I'm not an expert in how smoke rings work, but 930 00:44:16,280 --> 00:44:18,759 Speaker 2: imagine that. Then you could maybe describe that using the 931 00:44:18,760 --> 00:44:22,279 Speaker 2: same kind of mathematics you could use to describe electrons. 932 00:44:22,480 --> 00:44:24,760 Speaker 2: So you might call that a smoke on or whatever. 933 00:44:25,480 --> 00:44:29,000 Speaker 1: But it maybe just even more typical like a wave 934 00:44:29,000 --> 00:44:32,399 Speaker 1: in the ocean. You can use wave equations to describe them, 935 00:44:32,520 --> 00:44:35,200 Speaker 1: mm hmmm, and they're just ripples in the body of water. 936 00:44:35,360 --> 00:44:37,799 Speaker 1: So in a way, they're sort of just like water ons. Right. 937 00:44:38,080 --> 00:44:41,480 Speaker 2: Yes, not every wave phenomenon can describe a particle like 938 00:44:41,480 --> 00:44:45,799 Speaker 2: a particle's a special kind of persistent, discrete wave phenomenon. 939 00:44:46,320 --> 00:44:48,800 Speaker 2: But yeah, in the end, it's all rooted in wave 940 00:44:48,920 --> 00:44:52,560 Speaker 2: descriptions of how a medium is moving. And we talk 941 00:44:52,640 --> 00:44:55,960 Speaker 2: about sound waves as like phonons. It's like a basic 942 00:44:56,160 --> 00:44:58,880 Speaker 2: unit of the sound wave. Can you describe all sound 943 00:44:58,920 --> 00:45:02,560 Speaker 2: in terms of these like sound quasi particles. That's what 944 00:45:02,600 --> 00:45:03,799 Speaker 2: a phonon is. 945 00:45:05,440 --> 00:45:07,520 Speaker 1: Where I guess if we're following the same convention here, 946 00:45:07,560 --> 00:45:13,040 Speaker 1: it would be aerons perhaps depending on what the or gasons. 947 00:45:13,160 --> 00:45:15,200 Speaker 2: Yeah, if you want to reinvent stuff that already has 948 00:45:15,280 --> 00:45:18,560 Speaker 2: names for it so that everybody gets totally confused, then perfect. 949 00:45:18,280 --> 00:45:21,680 Speaker 1: Yes, Yeah, to make it clearer. Perhaps there is. 950 00:45:21,600 --> 00:45:25,240 Speaker 2: A thing called phonons, and there's lots of these quasi particles. 951 00:45:25,239 --> 00:45:27,840 Speaker 2: People are discovering new ones all the time. You know. 952 00:45:27,880 --> 00:45:32,640 Speaker 2: There's things called anions, and plasmons are an example of 953 00:45:32,719 --> 00:45:37,160 Speaker 2: a quasi particle. There are particular kinds of oscillations. But 954 00:45:37,360 --> 00:45:41,920 Speaker 2: in plasma, so plasma is just gas that's really really hot, 955 00:45:42,480 --> 00:45:45,440 Speaker 2: Like take hydrogen. It's got a proton and an electron. 956 00:45:45,719 --> 00:45:47,920 Speaker 2: The electron is bound to the proton because it doesn't 957 00:45:47,920 --> 00:45:50,319 Speaker 2: have the energy to fly away. Well, if you give 958 00:45:50,320 --> 00:45:53,520 Speaker 2: that electron more energy so that it's moving like too 959 00:45:53,680 --> 00:45:56,760 Speaker 2: fast to be bound by the proton, then it's free 960 00:45:56,960 --> 00:45:59,320 Speaker 2: and now you have a gas of protons and electrons 961 00:45:59,320 --> 00:46:01,880 Speaker 2: instead of a gas of hydrogen. That's a plasma. 962 00:46:02,520 --> 00:46:07,080 Speaker 1: Now it is a plasma. Then basically a phonon in plasma. 963 00:46:06,840 --> 00:46:09,480 Speaker 2: Well, the phonon is like a density wave, and that's 964 00:46:09,520 --> 00:46:13,040 Speaker 2: ignoring the charge distribution. Plasma is a little bit more 965 00:46:13,080 --> 00:46:14,719 Speaker 2: than that because it also has to do with the 966 00:46:14,840 --> 00:46:18,440 Speaker 2: charge distribution, because once you have a gas that has 967 00:46:18,560 --> 00:46:21,200 Speaker 2: charges in it, there's more kinds of forces that it 968 00:46:21,200 --> 00:46:24,799 Speaker 2: can feel like hydrogen pressure passes through it because the 969 00:46:24,840 --> 00:46:27,920 Speaker 2: particles are bumping up against each other. But in a plasma, 970 00:46:28,280 --> 00:46:31,600 Speaker 2: pressure can move through it because the charges are repelling 971 00:46:31,600 --> 00:46:33,960 Speaker 2: and attracting each other. So you have it's sort of 972 00:46:34,000 --> 00:46:35,799 Speaker 2: like two gases on top of each other. You have 973 00:46:35,840 --> 00:46:38,719 Speaker 2: a positive and a negative gas on top of each other, 974 00:46:38,960 --> 00:46:41,920 Speaker 2: and they're pushing and pulling on each other. If everything 975 00:46:41,960 --> 00:46:46,040 Speaker 2: has infinite time to sit around, it'll equilibrate, but that's 976 00:46:46,080 --> 00:46:48,279 Speaker 2: not usually what happens. You form these things in high 977 00:46:48,280 --> 00:46:51,360 Speaker 2: intensity situations. You have pulses in them, et cetera. And 978 00:46:51,400 --> 00:46:54,920 Speaker 2: so plasma is a description of the oscillation of mostly 979 00:46:54,920 --> 00:46:57,799 Speaker 2: the electrons, but also a little bit of protons due 980 00:46:57,800 --> 00:46:59,640 Speaker 2: to the charges of these things. 981 00:47:00,040 --> 00:47:00,239 Speaker 4: HM. 982 00:47:00,640 --> 00:47:04,000 Speaker 1: So you have this plasma of electrons and protons floating around, 983 00:47:04,040 --> 00:47:06,880 Speaker 1: flying around, and sometimes because of the dynamics between the 984 00:47:06,920 --> 00:47:11,200 Speaker 1: different particles, you get these weird little effects that move 985 00:47:11,280 --> 00:47:14,239 Speaker 1: around like they were particles inside of the plasma, and 986 00:47:14,239 --> 00:47:16,280 Speaker 1: that's what you call a plasma exactly. 987 00:47:16,520 --> 00:47:19,560 Speaker 2: And that's actually related to the previous question because the 988 00:47:19,680 --> 00:47:23,040 Speaker 2: reason these electrons are moving is because there's an electric field. 989 00:47:23,440 --> 00:47:26,360 Speaker 2: Often the electric field is because the electrons are separated 990 00:47:26,400 --> 00:47:29,360 Speaker 2: from the protons, so they've created an electric field between them. 991 00:47:29,560 --> 00:47:32,239 Speaker 2: So now the electrons move to try to balance out 992 00:47:32,239 --> 00:47:35,000 Speaker 2: that electric field that they had a part in making. 993 00:47:35,360 --> 00:47:38,319 Speaker 2: But sometimes they overshoot and so they oscillate back and 994 00:47:38,360 --> 00:47:40,560 Speaker 2: forth and back and forth. So you get all these 995 00:47:40,560 --> 00:47:44,239 Speaker 2: sort of like oscillations of the electrons because of their 996 00:47:44,320 --> 00:47:49,319 Speaker 2: charge differential, and those oscillations we can call plasmads. This 997 00:47:49,400 --> 00:47:51,720 Speaker 2: is like people trying to make connections between different fields 998 00:47:51,760 --> 00:47:53,839 Speaker 2: of physics. They're like, oh, people have all these cool 999 00:47:53,880 --> 00:47:57,279 Speaker 2: mathematical tools they can use to describe waves as particles. 1000 00:47:57,719 --> 00:47:59,879 Speaker 2: Maybe if we apply that to our situation, we'll try 1001 00:47:59,920 --> 00:48:03,440 Speaker 2: to gain some understanding. This is all about like emergent physics, 1002 00:48:03,520 --> 00:48:06,040 Speaker 2: Like should we take a step up from the microphysics 1003 00:48:06,080 --> 00:48:09,560 Speaker 2: and try to understand the bigger picture immersion phenomenon. Should 1004 00:48:09,560 --> 00:48:11,560 Speaker 2: you think about the water particles or should you think 1005 00:48:11,560 --> 00:48:14,560 Speaker 2: about the waves? Right? It depends again on the questions 1006 00:48:14,600 --> 00:48:16,799 Speaker 2: you're asking and which tools you want to bring to bear. 1007 00:48:17,480 --> 00:48:19,520 Speaker 2: We don't have a fundamental theory of physics that can 1008 00:48:19,600 --> 00:48:21,480 Speaker 2: answer every question we can ask, so we have to 1009 00:48:21,520 --> 00:48:23,480 Speaker 2: sort of choose, like how to zoom in, how to 1010 00:48:23,560 --> 00:48:26,600 Speaker 2: zoom out, what approximations to make, what things to focus on, 1011 00:48:26,640 --> 00:48:29,680 Speaker 2: what things to ignore. So plasmas can be useful for 1012 00:48:29,760 --> 00:48:32,480 Speaker 2: some kinds of questions in plasma physics. 1013 00:48:32,280 --> 00:48:34,880 Speaker 1: Like what kinds of questions? Like what are these useful for? 1014 00:48:35,120 --> 00:48:37,960 Speaker 2: Like how do keep plasma stable? You know, in magnetic 1015 00:48:38,000 --> 00:48:40,799 Speaker 2: confinement fusion, when you get plasmas really really hot and 1016 00:48:40,840 --> 00:48:43,879 Speaker 2: you hope that the protons will fuse sometimes and then 1017 00:48:43,920 --> 00:48:47,640 Speaker 2: create more fusion, you're really interested in these kinds of oscillations. 1018 00:48:47,920 --> 00:48:51,400 Speaker 2: The thing that makes magnetic confinement and fusion difficult is 1019 00:48:51,400 --> 00:48:54,279 Speaker 2: that plasmas are really hard to keep stable. They're very 1020 00:48:54,320 --> 00:48:58,760 Speaker 2: turbulent and very chaotic. So understanding the oscillations and a plasma, 1021 00:48:58,880 --> 00:49:00,680 Speaker 2: how to keep those stable high, to keep those from 1022 00:49:00,719 --> 00:49:03,719 Speaker 2: spiraling out of control and creating chaos that breaks up 1023 00:49:03,719 --> 00:49:07,080 Speaker 2: the plasma and ruins the fusion conditions can really help 1024 00:49:07,120 --> 00:49:10,120 Speaker 2: you build like a long lasting fusion reaction, which is 1025 00:49:10,440 --> 00:49:12,760 Speaker 2: the whole idea of magnetic confinement fusion. 1026 00:49:13,600 --> 00:49:15,799 Speaker 1: That's kind of the holy grail of fusion, right, it 1027 00:49:15,840 --> 00:49:19,120 Speaker 1: was super clean energy that will last us forever. Like 1028 00:49:19,280 --> 00:49:22,080 Speaker 1: we can control plasma and then we can basically replicate 1029 00:49:22,120 --> 00:49:23,319 Speaker 1: what's going on inside the sun. 1030 00:49:23,480 --> 00:49:26,279 Speaker 2: Yeah, that's exactly right. We need to understand plasma oscillations 1031 00:49:26,320 --> 00:49:29,279 Speaker 2: if we have any hope of keeping plasma stable and 1032 00:49:29,320 --> 00:49:32,440 Speaker 2: getting fusion, which is the energy source of the universe 1033 00:49:32,480 --> 00:49:35,600 Speaker 2: in the end. So plasmas can be really helpful for 1034 00:49:35,640 --> 00:49:38,120 Speaker 2: answering some questions about plasmas. 1035 00:49:39,000 --> 00:49:42,839 Speaker 1: And crossword puzzles. Apparently, I wonder which one is more 1036 00:49:42,920 --> 00:49:43,880 Speaker 1: useful to humanity. 1037 00:49:44,000 --> 00:49:46,080 Speaker 2: I don't know, but maybe you and Peter can answer 1038 00:49:46,120 --> 00:49:49,560 Speaker 2: these crossword puzzles as you drink mohtos on your private island. 1039 00:49:50,480 --> 00:49:52,840 Speaker 1: That sounds wonderful. It's going to be me, Dan, John 1040 00:49:52,960 --> 00:49:57,040 Speaker 1: and Peter drinking mojitos solving crossword puzzles in my private 1041 00:49:57,080 --> 00:49:59,960 Speaker 1: island while we get wiser and older. 1042 00:50:01,280 --> 00:50:02,200 Speaker 2: That sounds good to me. 1043 00:50:02,520 --> 00:50:05,640 Speaker 1: Wait, wait, are you Dan or not? Were you just 1044 00:50:05,640 --> 00:50:06,680 Speaker 1: happy for us? 1045 00:50:07,520 --> 00:50:09,640 Speaker 2: I'm the quantum interference between Dan and Daniel. 1046 00:50:10,760 --> 00:50:13,120 Speaker 1: Yeah, I need to know which one we're getting here. 1047 00:50:13,239 --> 00:50:16,120 Speaker 1: All right. Well, those are three awesome questions we've answered today. 1048 00:50:16,200 --> 00:50:18,640 Speaker 1: Thank you to all of our question askers. 1049 00:50:18,480 --> 00:50:20,959 Speaker 2: And thanks to everybody who writes in with questions about 1050 00:50:20,960 --> 00:50:24,240 Speaker 2: the universe. Keep thinking deeply, keep asking questions, and don't 1051 00:50:24,239 --> 00:50:26,240 Speaker 2: give up until it makes sense to you. 1052 00:50:26,360 --> 00:50:29,080 Speaker 1: And or you get an answer from Daniel or us 1053 00:50:29,120 --> 00:50:32,640 Speaker 1: on the podcast that's right, or maybe shows up in 1054 00:50:32,640 --> 00:50:34,560 Speaker 1: a crossword puzzle. Either way to thrill. 1055 00:50:34,680 --> 00:50:36,200 Speaker 2: And if you don't hear from me, feel free to 1056 00:50:36,200 --> 00:50:38,000 Speaker 2: look up poor his address and take him up on 1057 00:50:38,040 --> 00:50:39,560 Speaker 2: his invitation to the private island. 1058 00:50:40,160 --> 00:50:42,719 Speaker 1: Yeah there you go. All right, Well, we hope you 1059 00:50:42,840 --> 00:50:45,600 Speaker 1: enjoyed that. Thanks for joining us, See you next time. 1060 00:50:50,280 --> 00:50:53,080 Speaker 2: For more science and curiosity, come find us on social 1061 00:50:53,160 --> 00:50:58,120 Speaker 2: media where we answer questions and post videos. We're on Twitter, Discord, Instant, 1062 00:50:58,200 --> 00:51:01,880 Speaker 2: and now TikTok. Thanks for listening, and remember that Daniel 1063 00:51:01,920 --> 00:51:05,400 Speaker 2: and Jorge Explain the Universe is a production of iHeartRadio. 1064 00:51:05,640 --> 00:51:10,799 Speaker 2: For more podcasts from iHeartRadio, visit the iHeartRadio app, Apple Podcasts, 1065 00:51:10,920 --> 00:51:13,280 Speaker 2: or wherever you listen to your favorite shows.