1 00:00:04,400 --> 00:00:07,800 Speaker 1: Welcome to Tech Stuff, a production from I Heart Radio. 2 00:00:11,800 --> 00:00:14,760 Speaker 1: Hey there, and welcome to tech Stuff. I'm your host, 3 00:00:14,920 --> 00:00:18,200 Speaker 1: Jonathan Strickland. I'm an executive producer with I Heart Radio 4 00:00:18,440 --> 00:00:21,000 Speaker 1: and how the tech are you? All right? I'm gonna 5 00:00:21,040 --> 00:00:26,440 Speaker 1: start this episode with a rant that arguably is almost 6 00:00:26,480 --> 00:00:29,200 Speaker 1: moot at this point and is certainly tangion shoaled to 7 00:00:29,240 --> 00:00:32,159 Speaker 1: the episode, But it has to do with bookstores and 8 00:00:32,240 --> 00:00:36,279 Speaker 1: how they classify types of books. Now, if you've ever 9 00:00:36,320 --> 00:00:39,120 Speaker 1: been in a bookstore, like a brick and mortar bookstore, 10 00:00:39,240 --> 00:00:44,320 Speaker 1: and then you've looked around at the various categories like mystery, history, romance, 11 00:00:44,320 --> 00:00:47,200 Speaker 1: all that sort of stuff, chances are at some point 12 00:00:47,400 --> 00:00:50,320 Speaker 1: you encountered a section that was called something like science 13 00:00:50,320 --> 00:00:54,040 Speaker 1: fiction and fantasy, and you would have your swords all 14 00:00:54,120 --> 00:00:57,080 Speaker 1: mixed up with your lasers. In a quick shout out 15 00:00:57,080 --> 00:00:59,160 Speaker 1: to the podcast Sword and Laser, which is pretty dark 16 00:00:59,200 --> 00:01:02,520 Speaker 1: and great. Ut I've always been kind of grouchy about this. 17 00:01:02,720 --> 00:01:05,440 Speaker 1: I felt that while science fiction and fantasy both fall 18 00:01:06,000 --> 00:01:11,120 Speaker 1: into the realm of speculative fiction, they aren't the only ones. 19 00:01:11,160 --> 00:01:14,240 Speaker 1: I mean a lot of horror falls into that as well, 20 00:01:14,319 --> 00:01:16,880 Speaker 1: But horror doesn't tend to be grouped with science fiction 21 00:01:16,920 --> 00:01:20,520 Speaker 1: and fantasy. And of course psychological horror might not fit 22 00:01:20,560 --> 00:01:24,000 Speaker 1: into speculative fiction, like a person going on some sort 23 00:01:24,040 --> 00:01:26,399 Speaker 1: of rampage or something, but the kind of horror where 24 00:01:26,400 --> 00:01:29,440 Speaker 1: a fear feeding alien who looks like a clown definitely 25 00:01:29,480 --> 00:01:33,639 Speaker 1: falls into that category. But still horror gets its own section. 26 00:01:33,720 --> 00:01:36,240 Speaker 1: So why not science fiction and fantasy? And I guess 27 00:01:36,280 --> 00:01:39,319 Speaker 1: I'm touchy about this because my parents are authors. Dad 28 00:01:39,319 --> 00:01:42,200 Speaker 1: in particular has written a lot of science fiction, fantasy, 29 00:01:42,240 --> 00:01:45,679 Speaker 1: and horror novels, as well as mystery novels and also 30 00:01:45,760 --> 00:01:48,120 Speaker 1: young adult novel You know what, Dad's written a lot 31 00:01:48,160 --> 00:01:51,680 Speaker 1: of stuff, and I just thought it's weird that his 32 00:01:51,760 --> 00:01:54,320 Speaker 1: science fiction books and fantasy books would appear side by 33 00:01:54,360 --> 00:01:58,080 Speaker 1: side in the same section. In fact, his agent and 34 00:01:58,120 --> 00:02:01,639 Speaker 1: publishers were so concerned about this that at one point 35 00:02:01,840 --> 00:02:04,280 Speaker 1: he had to write under a pen name for a 36 00:02:04,360 --> 00:02:07,640 Speaker 1: science fiction book so that it wouldn't be right next 37 00:02:07,720 --> 00:02:12,040 Speaker 1: to his fantasy books. Now, none of that really matters 38 00:02:12,040 --> 00:02:15,520 Speaker 1: for this episode, except there is an element that can 39 00:02:15,600 --> 00:02:19,640 Speaker 1: be found both in fantasy books and science fiction books 40 00:02:19,880 --> 00:02:22,320 Speaker 1: as well as other media that I'm going to talk 41 00:02:22,360 --> 00:02:26,600 Speaker 1: about today, and that's stuff. What turns you invisible. Now, 42 00:02:26,639 --> 00:02:30,240 Speaker 1: in fantasy, it might be an actual cloak, so you 43 00:02:30,320 --> 00:02:34,360 Speaker 1: really have a cloaking an invisibility cloak. It might be 44 00:02:34,560 --> 00:02:36,600 Speaker 1: a ring that at some point you can't have to 45 00:02:36,680 --> 00:02:39,400 Speaker 1: chuck into a volcano. It might be a spell or 46 00:02:39,440 --> 00:02:43,440 Speaker 1: a potion, whereas in science fiction it might be some 47 00:02:43,480 --> 00:02:47,480 Speaker 1: sort of technology that's incorporated in say a spaceship, that 48 00:02:47,520 --> 00:02:50,040 Speaker 1: allows it to pass undetected as it sneaks up on 49 00:02:50,120 --> 00:02:54,840 Speaker 1: an enemy or encounters an alien world. Now, I thought 50 00:02:55,560 --> 00:02:59,560 Speaker 1: we might talk a bit about tech intended to grant 51 00:03:00,080 --> 00:03:04,400 Speaker 1: invisibility in the real world. We've got some real world 52 00:03:04,400 --> 00:03:07,120 Speaker 1: examples of stuff that does this to a certain degree, 53 00:03:07,160 --> 00:03:11,000 Speaker 1: though spoiler alert, we do not have a technology that 54 00:03:11,040 --> 00:03:14,560 Speaker 1: can cover the entire visual spectrum of light that would 55 00:03:14,560 --> 00:03:18,760 Speaker 1: work like an invisibility cloak or something. There are folks 56 00:03:18,800 --> 00:03:23,560 Speaker 1: working on it, but we're definitely not there yet. However, 57 00:03:23,600 --> 00:03:26,960 Speaker 1: we do have some really interesting examples that at least 58 00:03:27,000 --> 00:03:31,720 Speaker 1: brush up against invisibility that we'll talk about. Now, before 59 00:03:31,760 --> 00:03:34,960 Speaker 1: we dive into the various technologies, let's talk about how 60 00:03:35,400 --> 00:03:40,400 Speaker 1: vision works and chat a bit about light. So, way 61 00:03:40,440 --> 00:03:44,040 Speaker 1: back in the day, smarty pans philosopher types tried to 62 00:03:44,080 --> 00:03:48,720 Speaker 1: suss out what is light and how does vision work. 63 00:03:49,360 --> 00:03:53,280 Speaker 1: Pythagoras had the angle on some stuff, but when it 64 00:03:53,360 --> 00:03:55,360 Speaker 1: came to how vision works, he ended up being a 65 00:03:55,360 --> 00:03:58,600 Speaker 1: bit obtuse. Yes, I'm gonna throw in lots of puns 66 00:03:58,600 --> 00:04:02,960 Speaker 1: and dad jokes. Anyway, Pythagoras thought that vision worked because 67 00:04:03,000 --> 00:04:07,800 Speaker 1: we were effectively shooting out rays of vision with our eyeballs, 68 00:04:07,840 --> 00:04:11,400 Speaker 1: like vision was something that came from us, extended out 69 00:04:11,440 --> 00:04:15,840 Speaker 1: into the world and effectively lit the world around us 70 00:04:15,840 --> 00:04:19,480 Speaker 1: with vision, and so these vision rays would go out 71 00:04:19,480 --> 00:04:23,080 Speaker 1: and hit objects, which let us see them. So we 72 00:04:23,080 --> 00:04:26,839 Speaker 1: were kind of like Superman with this heat vision, except 73 00:04:27,000 --> 00:04:31,800 Speaker 1: we're just constantly shooting out this sort of light. And 74 00:04:31,880 --> 00:04:35,039 Speaker 1: you might think, silly Pathagoras, wouldn't that mean we could 75 00:04:35,080 --> 00:04:37,440 Speaker 1: all see in the dark. But maybe what he was 76 00:04:37,440 --> 00:04:39,400 Speaker 1: saying is that, you know, some of this light that 77 00:04:39,560 --> 00:04:42,320 Speaker 1: is invisible to us in the world, like we can't 78 00:04:42,400 --> 00:04:46,240 Speaker 1: see it shooting out of everybody else's eyes, but the 79 00:04:46,640 --> 00:04:49,359 Speaker 1: it's what comes out of our eyes and hit stuff 80 00:04:49,400 --> 00:04:51,760 Speaker 1: that's already lit, and that's what lets us see it. 81 00:04:52,680 --> 00:04:55,000 Speaker 1: And so he was just thinking it was an innate 82 00:04:55,200 --> 00:05:00,440 Speaker 1: ability within the human eye and presumably animal eye as well. 83 00:05:01,000 --> 00:05:04,640 Speaker 1: Epicurus had a totally different take on it. The philosopher 84 00:05:04,680 --> 00:05:07,920 Speaker 1: known for emphasizing the pursuit of a happy life through 85 00:05:08,200 --> 00:05:12,800 Speaker 1: eliminating fear and pain, which sounds nice, felt that objects 86 00:05:12,839 --> 00:05:18,160 Speaker 1: themselves were emitting this light, that they were emitting this 87 00:05:18,400 --> 00:05:22,479 Speaker 1: visible ray that our eyes could detect. So our eyes 88 00:05:22,520 --> 00:05:26,839 Speaker 1: are detectors, but the objects themselves are emitting this, and 89 00:05:26,920 --> 00:05:29,840 Speaker 1: that as a result, we could see light coming from 90 00:05:29,920 --> 00:05:32,760 Speaker 1: the objects. Again, this doesn't really hold up when you're 91 00:05:32,760 --> 00:05:34,680 Speaker 1: wandering around your house in the dark and you bark 92 00:05:34,720 --> 00:05:36,800 Speaker 1: your ship on a coffee table. But what he was 93 00:05:36,880 --> 00:05:39,720 Speaker 1: saying was that, all right, you're in a well lit area. 94 00:05:40,279 --> 00:05:44,360 Speaker 1: Every single object that has this thing in it allows 95 00:05:44,400 --> 00:05:47,520 Speaker 1: you to see it because it's emanating this energy that 96 00:05:47,560 --> 00:05:51,760 Speaker 1: your eyes can detect. So a little closer to being 97 00:05:51,760 --> 00:05:55,840 Speaker 1: correct than Pythagoras, but still missing stuff. Now you also 98 00:05:55,839 --> 00:05:58,200 Speaker 1: had philosophers who started to get a little closer to 99 00:05:58,279 --> 00:06:01,920 Speaker 1: what we know to be the truth that light can 100 00:06:01,960 --> 00:06:05,839 Speaker 1: reflect off surfaces, bouncing off of them, or that it 101 00:06:05,880 --> 00:06:10,640 Speaker 1: can pass through certain types of material like glass or water. 102 00:06:11,360 --> 00:06:14,640 Speaker 1: But when it does, when light travels from that and 103 00:06:14,880 --> 00:06:18,160 Speaker 1: hits something like the surface of glass or the surface 104 00:06:18,200 --> 00:06:23,080 Speaker 1: of water, it bends, the light changes direction. Now these 105 00:06:23,120 --> 00:06:29,479 Speaker 1: observations gradually lead to later smarty pants folks crafting lenses 106 00:06:29,880 --> 00:06:33,919 Speaker 1: intended to bend light in specific ways. Not just you 107 00:06:33,960 --> 00:06:36,280 Speaker 1: know it, not just it bends light, but I want 108 00:06:36,320 --> 00:06:39,240 Speaker 1: to bend light so that it goes to this specific point. 109 00:06:39,920 --> 00:06:44,279 Speaker 1: And an Arabic polymath in what is today known as 110 00:06:44,320 --> 00:06:49,839 Speaker 1: Iraq even al hythem I figured that the human eye 111 00:06:49,880 --> 00:06:52,200 Speaker 1: was doing the same sort of thing as a surface 112 00:06:52,240 --> 00:06:56,160 Speaker 1: of glass or water. That light when it goes into 113 00:06:56,240 --> 00:07:01,440 Speaker 1: the human eye would end up being directed. And also 114 00:07:01,839 --> 00:07:04,039 Speaker 1: that light when it's going out in the world, it's 115 00:07:04,080 --> 00:07:07,360 Speaker 1: bouncing off of objects, and it's the light bouncing off 116 00:07:07,400 --> 00:07:11,560 Speaker 1: those objects that passes through the human eye against bent 117 00:07:11,640 --> 00:07:14,720 Speaker 1: in a way where we can perceive it, and thus 118 00:07:14,760 --> 00:07:18,760 Speaker 1: that's how vision works. This was around one thousand CE, 119 00:07:19,160 --> 00:07:24,840 Speaker 1: or a d if you're using the more common nomenclature. Now. 120 00:07:24,960 --> 00:07:29,680 Speaker 1: By the early seventeen hundreds we had Isaac Newton proposing 121 00:07:29,720 --> 00:07:34,760 Speaker 1: that light was made of little corpuscles, little particles. In 122 00:07:34,760 --> 00:07:39,600 Speaker 1: other words, that light really was made up of some tiny, tiny, 123 00:07:39,680 --> 00:07:44,040 Speaker 1: tiny little piece of something. And it made some sense 124 00:07:44,720 --> 00:07:48,320 Speaker 1: because light travels in a straight line, and it bounces 125 00:07:48,400 --> 00:07:51,200 Speaker 1: off objects, just as a physical particle would do. Like 126 00:07:51,240 --> 00:07:53,560 Speaker 1: if you had a tennis ball, then you threw it 127 00:07:53,560 --> 00:07:55,520 Speaker 1: at a wall, it would bounce off the wall, and 128 00:07:55,960 --> 00:07:59,600 Speaker 1: depending on the angle you threw the ball at and 129 00:07:59,640 --> 00:08:02,080 Speaker 1: then that it hits the wall at, it's going to 130 00:08:02,200 --> 00:08:05,440 Speaker 1: bounce in a specific way. Well, what Newton was saying, 131 00:08:05,640 --> 00:08:07,360 Speaker 1: light appears to be doing the same thing. So it 132 00:08:07,440 --> 00:08:09,720 Speaker 1: must be made of lots of tiny little tennis balls, 133 00:08:10,040 --> 00:08:12,320 Speaker 1: although he didn't say tennis balls, but you know, just 134 00:08:12,400 --> 00:08:17,160 Speaker 1: to continue the analogy. Others, however, would describe light as 135 00:08:17,200 --> 00:08:21,160 Speaker 1: behaving like a wave, like a sound wave. And as 136 00:08:21,200 --> 00:08:24,640 Speaker 1: it would turn out, both explanations were kind of right. 137 00:08:24,800 --> 00:08:28,640 Speaker 1: Light behaves as a wave and a particle, but we 138 00:08:28,680 --> 00:08:31,520 Speaker 1: wouldn't be sure about that for you know, a couple 139 00:08:31,640 --> 00:08:35,120 Speaker 1: hundred years. But thinking about light as either a particle 140 00:08:35,240 --> 00:08:38,520 Speaker 1: or a wave helps us understand what it's doing when 141 00:08:38,559 --> 00:08:42,680 Speaker 1: it encounters other stuff. So let's start by thinking of 142 00:08:42,880 --> 00:08:46,320 Speaker 1: as a ray of particles, and it's a ray that 143 00:08:46,360 --> 00:08:49,920 Speaker 1: travels in a straight line until it encounters something else. 144 00:08:50,520 --> 00:08:52,680 Speaker 1: And let's talk about how light interacts with stuff. So 145 00:08:52,760 --> 00:08:56,240 Speaker 1: first up, as reflection, This is when light bounces off 146 00:08:56,280 --> 00:08:59,840 Speaker 1: of a surface like a mirror or a tree where 147 00:08:59,840 --> 00:09:03,319 Speaker 1: you our face. So light will bounce off a smooth 148 00:09:03,360 --> 00:09:05,800 Speaker 1: surface at an angle equal to the angle of the 149 00:09:05,840 --> 00:09:10,000 Speaker 1: incoming ray, making with the surface like there's a thing 150 00:09:10,080 --> 00:09:14,120 Speaker 1: called the angle of incidents, and so you can predict 151 00:09:14,160 --> 00:09:16,600 Speaker 1: what that angle is going to be if you're working 152 00:09:16,600 --> 00:09:19,839 Speaker 1: with a perfectly smooth surface. This is what we call 153 00:09:19,880 --> 00:09:24,800 Speaker 1: the law of reflection. However, we don't have perfectly smooth surfaces. 154 00:09:24,880 --> 00:09:28,000 Speaker 1: If we did, then yes, you would see light bend 155 00:09:28,000 --> 00:09:29,920 Speaker 1: in this way or reflect off in this way every 156 00:09:29,920 --> 00:09:34,120 Speaker 1: single time. But we don't have perfectly smooth surfaces. Instead, 157 00:09:34,800 --> 00:09:39,480 Speaker 1: we've got surfaces that have imperfections. And because of this, 158 00:09:39,559 --> 00:09:43,360 Speaker 1: and because the wavelengths of light are very very very small, 159 00:09:44,080 --> 00:09:47,240 Speaker 1: light will bounce off at all sorts of angles because 160 00:09:47,480 --> 00:09:51,040 Speaker 1: again not perfectly smooth. This is why something like a 161 00:09:51,120 --> 00:09:54,240 Speaker 1: tabletop won't disappear if you change your angle of view, 162 00:09:54,880 --> 00:09:57,080 Speaker 1: right like if it if the light bounced in a 163 00:09:57,200 --> 00:10:00,600 Speaker 1: very specific way because you had a perfectly smooth table, 164 00:10:01,480 --> 00:10:03,920 Speaker 1: well that would mean that if you moved out of 165 00:10:04,000 --> 00:10:06,480 Speaker 1: the angle of incidents, you would no longer see the 166 00:10:06,520 --> 00:10:09,360 Speaker 1: tabletop because there will be no light bouncing off of 167 00:10:09,400 --> 00:10:12,080 Speaker 1: it that you could see, which is kind of weird 168 00:10:12,120 --> 00:10:14,480 Speaker 1: to think about, like the idea that something exists in 169 00:10:14,640 --> 00:10:19,440 Speaker 1: one perspective, but at another it seems to not exist anymore. 170 00:10:19,440 --> 00:10:22,360 Speaker 1: It does, you just can't see it. There are other 171 00:10:22,400 --> 00:10:24,920 Speaker 1: reasons why it's gonna be don't have perfectly smooth tabletops. 172 00:10:24,920 --> 00:10:27,160 Speaker 1: The big one being that if you had a perfectly 173 00:10:27,160 --> 00:10:29,440 Speaker 1: smooth tabletop, there will be no friction. If you said 174 00:10:29,440 --> 00:10:31,760 Speaker 1: anything on the surface of the tabletopic could slide all 175 00:10:31,760 --> 00:10:35,319 Speaker 1: over the place. But we'll leave that beat. But then 176 00:10:35,360 --> 00:10:39,720 Speaker 1: you've got absorption. Okay, so stuff can absorb light. Now, 177 00:10:39,720 --> 00:10:41,600 Speaker 1: I'm sure you all know about the spectrum of light. 178 00:10:41,600 --> 00:10:43,960 Speaker 1: We're gonna be talking about a lot in this episode. 179 00:10:44,440 --> 00:10:49,000 Speaker 1: That's the old roy g biv red, orange, yellow, green, blue, indigo, 180 00:10:49,080 --> 00:10:51,440 Speaker 1: and violet. That's the order that you would see if 181 00:10:51,440 --> 00:10:53,800 Speaker 1: you were to see a rainbow. Well, that happens to 182 00:10:53,800 --> 00:10:56,120 Speaker 1: be the spectrum of visible light. It's going from the 183 00:10:56,240 --> 00:11:00,800 Speaker 1: longest wavelength red to the shortest violet. But we're gonna 184 00:11:00,840 --> 00:11:03,720 Speaker 1: talk more about wavelengths in a little bit, and a 185 00:11:03,760 --> 00:11:08,600 Speaker 1: lot of matter can absorb certain wavelengths of light. That 186 00:11:08,640 --> 00:11:11,800 Speaker 1: means those wavelengths do not get reflected back at you 187 00:11:11,960 --> 00:11:16,040 Speaker 1: when the light hits that object. For example, chromium, the 188 00:11:16,040 --> 00:11:19,600 Speaker 1: stuff and rubies that makes them red, absorbs the green 189 00:11:19,679 --> 00:11:23,439 Speaker 1: and blue wavelengths of light, so the only stuff that's 190 00:11:23,440 --> 00:11:26,360 Speaker 1: getting reflected back is in the red wavelengths of light. 191 00:11:26,760 --> 00:11:30,079 Speaker 1: So rubies appear red to us because the other wavelengths 192 00:11:30,080 --> 00:11:33,320 Speaker 1: of light have been absorbed by the gem. If you 193 00:11:33,360 --> 00:11:36,840 Speaker 1: had something that could absorb all wavelengths of light, it 194 00:11:36,920 --> 00:11:41,120 Speaker 1: would look black, like pure black, as if there were 195 00:11:41,160 --> 00:11:45,160 Speaker 1: avoid rather than you know, whatever the thing is. And 196 00:11:45,200 --> 00:11:48,360 Speaker 1: there are special paints out there that absorbed nearly all 197 00:11:48,520 --> 00:11:51,600 Speaker 1: visible light hitting them, and seeing stuff covered in that 198 00:11:51,640 --> 00:11:55,280 Speaker 1: paint is trippy because it looks like there's just a 199 00:11:55,280 --> 00:12:00,680 Speaker 1: a thing shaped void in a physical space. So one 200 00:12:00,679 --> 00:12:04,720 Speaker 1: example I've seen as an apple that's been half painted 201 00:12:05,520 --> 00:12:10,480 Speaker 1: uh with this special super uber black paint, and you 202 00:12:10,559 --> 00:12:14,520 Speaker 1: put the apple on a little rotating pedestal, and what 203 00:12:14,640 --> 00:12:17,320 Speaker 1: you'll see is that when the apple rotates so that 204 00:12:17,440 --> 00:12:19,880 Speaker 1: the red of the apple starts to give way to 205 00:12:20,040 --> 00:12:24,360 Speaker 1: the void black, it looks like half the apple is missing, 206 00:12:24,880 --> 00:12:28,280 Speaker 1: but you're not seeing the inside of the apple. It's 207 00:12:28,320 --> 00:12:30,640 Speaker 1: just the half the apple is just a black shape, 208 00:12:30,960 --> 00:12:33,080 Speaker 1: and if it turns all the way around, it's like 209 00:12:33,080 --> 00:12:35,720 Speaker 1: the apple doesn't exist anymore. You just see a black 210 00:12:36,840 --> 00:12:41,520 Speaker 1: field in the shape of an apple. It's crazy. You 211 00:12:41,520 --> 00:12:43,080 Speaker 1: could do that with a pumpkin and you would have 212 00:12:43,080 --> 00:12:45,920 Speaker 1: a pumpkin shaped hole instead of a jack ol Internet Halloween, 213 00:12:45,960 --> 00:12:48,360 Speaker 1: which would be super awesome in the daytime, wouldn't be 214 00:12:48,400 --> 00:12:51,760 Speaker 1: so effective at night. But it is really neat stuff. 215 00:12:51,880 --> 00:12:54,720 Speaker 1: By the way, there are different types of this ultra 216 00:12:54,800 --> 00:12:59,640 Speaker 1: black paint out there. There's one kind that was heavily trademarked, 217 00:12:59,640 --> 00:13:02,280 Speaker 1: and then someone else went and developed a similar kind, 218 00:13:02,800 --> 00:13:05,920 Speaker 1: specifically because they felt it was wrong for someone to 219 00:13:05,960 --> 00:13:09,880 Speaker 1: try and trademark a color. But yeah, that's that's a 220 00:13:09,920 --> 00:13:13,600 Speaker 1: topic for another episode. Then we have when light goes 221 00:13:13,640 --> 00:13:18,640 Speaker 1: from one transparent medium to another, when it passes through 222 00:13:18,679 --> 00:13:23,200 Speaker 1: a barrier, and then what happens to it. So this 223 00:13:23,240 --> 00:13:26,320 Speaker 1: would be like when light travels through air, hits the 224 00:13:26,320 --> 00:13:29,880 Speaker 1: surface of water or air, and it hits a lens. 225 00:13:30,600 --> 00:13:34,880 Speaker 1: That's when you get refraction. Now I'll explain what refraction 226 00:13:34,960 --> 00:13:38,520 Speaker 1: is because it's very important for our discussion. But first 227 00:13:38,600 --> 00:13:51,000 Speaker 1: let's take a quick break. Okay, Before the break, I 228 00:13:51,040 --> 00:13:55,959 Speaker 1: was talking about refraction. Refraction is when light does pass 229 00:13:56,040 --> 00:13:59,480 Speaker 1: from one medium to another and it changes speed. Now 230 00:13:59,520 --> 00:14:03,800 Speaker 1: that might sound weird because everyone knows light is the 231 00:14:03,840 --> 00:14:07,240 Speaker 1: fastest stuff in the universe. It is the speed limit 232 00:14:07,440 --> 00:14:10,600 Speaker 1: of the universe. There is nothing faster than light. In fact, 233 00:14:10,800 --> 00:14:13,960 Speaker 1: we use the speed of light as a constant. The 234 00:14:14,120 --> 00:14:19,760 Speaker 1: famous equation E equals mc squared is referencing the speed 235 00:14:19,760 --> 00:14:23,800 Speaker 1: of light. That's energy equals the mass of something times 236 00:14:24,360 --> 00:14:27,040 Speaker 1: the square of the speed of light. So if it 237 00:14:27,200 --> 00:14:30,359 Speaker 1: is a constant, how can the speed of light change? 238 00:14:31,400 --> 00:14:34,400 Speaker 1: Those two things don't make sense. Well, when we talk 239 00:14:34,440 --> 00:14:38,000 Speaker 1: about the speed of light as a constant, we're referring 240 00:14:38,240 --> 00:14:44,000 Speaker 1: to light traveling through a vacuum, an empty medium, outer space, 241 00:14:44,880 --> 00:14:48,240 Speaker 1: outer space where you've got a true vacuum. But when 242 00:14:48,320 --> 00:14:53,240 Speaker 1: light hits a medium like say an atmosphere or water, 243 00:14:53,800 --> 00:14:57,400 Speaker 1: or the lens of a telescope or glasses, it does 244 00:14:57,440 --> 00:15:00,240 Speaker 1: slow down a little. It changes speed. It can't get 245 00:15:00,320 --> 00:15:03,480 Speaker 1: faster than it can through the vacuum of space. That's 246 00:15:03,480 --> 00:15:06,880 Speaker 1: the as fast as anything can go. But if it 247 00:15:07,000 --> 00:15:12,000 Speaker 1: hits something like trans transparent medium, it will change speed. 248 00:15:12,600 --> 00:15:15,960 Speaker 1: It slows down. Think of it kind of like walking 249 00:15:16,240 --> 00:15:19,160 Speaker 1: in just the open air, like you're going out for 250 00:15:19,200 --> 00:15:23,600 Speaker 1: a stroll, versus trying to walk in a swimming pool. 251 00:15:24,200 --> 00:15:25,840 Speaker 1: You know, when you're in a swing pool and you're 252 00:15:25,840 --> 00:15:29,000 Speaker 1: trying to walk across the pool, you feel the resistance 253 00:15:29,000 --> 00:15:31,880 Speaker 1: of all that water that slows you down, Whereas when 254 00:15:31,880 --> 00:15:35,720 Speaker 1: you're walking through just you know, the room, then all 255 00:15:35,760 --> 00:15:37,840 Speaker 1: you're doing is walking through air. You have much less 256 00:15:37,880 --> 00:15:40,200 Speaker 1: resistance and you're able to go much more quickly. It's 257 00:15:40,360 --> 00:15:44,440 Speaker 1: very similar to that. So when light changes speed as 258 00:15:44,480 --> 00:15:48,800 Speaker 1: it passes into a new medium, it bends. The amount 259 00:15:48,840 --> 00:15:52,160 Speaker 1: of bending or angle of refraction depends upon how much 260 00:15:52,200 --> 00:15:55,960 Speaker 1: slower the light will travel as it moves through the 261 00:15:56,000 --> 00:15:59,440 Speaker 1: new medium. In fact, we call this the refraction index 262 00:15:59,520 --> 00:16:02,800 Speaker 1: when we look at the different transparent media and we 263 00:16:02,880 --> 00:16:05,800 Speaker 1: say all right, well, based upon this difference, will know 264 00:16:05,920 --> 00:16:08,400 Speaker 1: how much of a bend will see in the light. 265 00:16:08,880 --> 00:16:10,600 Speaker 1: So if you've ever seen like a shaft of light 266 00:16:11,160 --> 00:16:16,160 Speaker 1: shining down to a a surface of water, then you're 267 00:16:16,400 --> 00:16:18,680 Speaker 1: looking at like a cross section, like you can see 268 00:16:18,680 --> 00:16:22,360 Speaker 1: both above and below the water. You actually see where 269 00:16:22,600 --> 00:16:24,760 Speaker 1: the bend is there. Or if you want to do 270 00:16:24,800 --> 00:16:26,960 Speaker 1: a really easy one, you get a glass you fill 271 00:16:27,000 --> 00:16:30,080 Speaker 1: it up with water, like maybe to the halfway point. 272 00:16:30,480 --> 00:16:32,640 Speaker 1: Put a straw on that glass, and then you look 273 00:16:32,680 --> 00:16:34,680 Speaker 1: at the glass from the side, and you'll see that 274 00:16:34,800 --> 00:16:38,000 Speaker 1: the straw appears to bend at the point where it 275 00:16:38,520 --> 00:16:43,320 Speaker 1: crosses over into the water. That's because of this refraction 276 00:16:43,560 --> 00:16:46,400 Speaker 1: and this refractive index and the difference between the two, 277 00:16:46,600 --> 00:16:50,120 Speaker 1: and we get that that little bend there. So a 278 00:16:50,240 --> 00:16:53,400 Speaker 1: lens is shaped in such a way as to bend 279 00:16:53,480 --> 00:16:55,800 Speaker 1: light to a specific focal point. If we're thinking of 280 00:16:55,840 --> 00:16:58,680 Speaker 1: it in the terms of rays, right, array coming in 281 00:16:59,160 --> 00:17:02,360 Speaker 1: at the edge of the lens, where it is more narrow, 282 00:17:02,760 --> 00:17:05,880 Speaker 1: is going to be bent a certain way. Array coming 283 00:17:05,920 --> 00:17:08,359 Speaker 1: in through the center of the lens is going to 284 00:17:08,440 --> 00:17:10,720 Speaker 1: go in a certain direction. And then at the very 285 00:17:10,720 --> 00:17:13,639 Speaker 1: bottom of the lens, which is again perhaps more narrow 286 00:17:13,720 --> 00:17:18,160 Speaker 1: we're looking at our typical lens, would then be bent 287 00:17:18,359 --> 00:17:20,680 Speaker 1: in a certain way so that these these different bent 288 00:17:20,960 --> 00:17:24,760 Speaker 1: rays of light will converge at a point where we 289 00:17:24,800 --> 00:17:27,359 Speaker 1: can get, say, an image. This is how we create 290 00:17:27,440 --> 00:17:31,560 Speaker 1: things like corrective lenses for glasses, and bending light is 291 00:17:31,600 --> 00:17:38,159 Speaker 1: really the secret sauce. In most invisibility technologies or cloaking technologies. 292 00:17:38,760 --> 00:17:41,280 Speaker 1: This is pretty easy to understand. There's another way to 293 00:17:41,320 --> 00:17:43,280 Speaker 1: look at this, by the way, and in fact, I 294 00:17:43,320 --> 00:17:45,440 Speaker 1: would argue the other way to look at it makes 295 00:17:45,480 --> 00:17:48,600 Speaker 1: it even easier to understand, which is to think of 296 00:17:48,640 --> 00:17:53,080 Speaker 1: the incoming light as waves and think of the lens 297 00:17:53,080 --> 00:17:56,160 Speaker 1: like let's say that we've got our our regular convex 298 00:17:56,280 --> 00:17:59,920 Speaker 1: lens where it's narrower at the top and bottom and 299 00:18:00,080 --> 00:18:03,840 Speaker 1: thickest in the middle. Right, the wave hitting the top 300 00:18:03,920 --> 00:18:07,000 Speaker 1: and the bottom, those waves are going to be slowed 301 00:18:07,040 --> 00:18:12,120 Speaker 1: down less than the wave that's hinting hitting the center 302 00:18:12,160 --> 00:18:16,640 Speaker 1: of that lens, because the the material is thinner at 303 00:18:16,640 --> 00:18:19,800 Speaker 1: the top and bottom and thicker in the middle. So 304 00:18:20,080 --> 00:18:22,200 Speaker 1: the waves at the top and bottom slow down a 305 00:18:22,240 --> 00:18:24,399 Speaker 1: little bit, but not a lot. The wave in the 306 00:18:24,400 --> 00:18:26,720 Speaker 1: middle slows down the most. And what you get on 307 00:18:26,760 --> 00:18:30,280 Speaker 1: the other side of the lens is this converging wave, 308 00:18:30,960 --> 00:18:34,480 Speaker 1: being the wave is starting to get uh smaller and 309 00:18:34,520 --> 00:18:39,000 Speaker 1: smaller to a focused point because of the the speed 310 00:18:39,560 --> 00:18:43,080 Speaker 1: at which it has traveled through that lens, and it converges, 311 00:18:43,359 --> 00:18:47,040 Speaker 1: and that's where you get your your focal point. That's 312 00:18:47,040 --> 00:18:49,360 Speaker 1: another way to think about it. It becomes really important 313 00:18:49,359 --> 00:18:54,320 Speaker 1: when we start talking about invisibility technologies. All right, something 314 00:18:54,400 --> 00:18:56,159 Speaker 1: else we have to know about light. It's part of 315 00:18:56,160 --> 00:18:59,320 Speaker 1: the electro magnetic spectrum. As I'm sure you're all know, 316 00:18:59,600 --> 00:19:03,400 Speaker 1: the visible of lights just one tiny part of of 317 00:19:03,440 --> 00:19:05,720 Speaker 1: a band of frequencies that make up what we call 318 00:19:05,880 --> 00:19:10,040 Speaker 1: light like light that we can see. That's one tiny 319 00:19:10,080 --> 00:19:14,080 Speaker 1: slice of light. Overall. There's also infrared light, which is 320 00:19:14,119 --> 00:19:17,280 Speaker 1: on one side of the visible spectrum, an ultraviolet light, 321 00:19:17,640 --> 00:19:21,040 Speaker 1: which is on the opposite side. We cannot see infrared 322 00:19:21,080 --> 00:19:24,560 Speaker 1: and ultra violet directly. We can create technologies that let 323 00:19:24,760 --> 00:19:29,439 Speaker 1: us detect this kind of light and then see it 324 00:19:29,600 --> 00:19:32,600 Speaker 1: in the sense of converting that into light that we 325 00:19:32,640 --> 00:19:37,960 Speaker 1: can actually directly perceive. Right, So, if you have infrared goggles, 326 00:19:38,800 --> 00:19:41,520 Speaker 1: you're not actually looking at infrared light. What you're looking 327 00:19:41,520 --> 00:19:46,840 Speaker 1: at is a interpretation of infrared that's been fed into 328 00:19:47,520 --> 00:19:50,440 Speaker 1: technology that gives you light that you can actually see, 329 00:19:50,720 --> 00:19:54,000 Speaker 1: so that things that are really hot appear red, and 330 00:19:54,040 --> 00:19:56,919 Speaker 1: things that are cooler might appear blue, that sort of stuff. 331 00:19:57,320 --> 00:20:00,160 Speaker 1: But the red and blue, that's red and blue. That's 332 00:20:00,200 --> 00:20:03,840 Speaker 1: not infrared. It's just it's been interpreted through the technology. However, 333 00:20:04,040 --> 00:20:06,320 Speaker 1: you took the the goggles off entirely, you wouldn't be 334 00:20:06,359 --> 00:20:08,240 Speaker 1: able to see anything because everything would be dark. That 335 00:20:08,320 --> 00:20:10,320 Speaker 1: kind of thing. It's night vision goggles work on a 336 00:20:10,359 --> 00:20:18,160 Speaker 1: similar idea. So that's where light fits. But then beyond light, 337 00:20:18,600 --> 00:20:21,640 Speaker 1: you've got all sorts of different types of electro magnetism, 338 00:20:22,320 --> 00:20:24,639 Speaker 1: Like you have different flavors of it if you would, 339 00:20:24,680 --> 00:20:28,760 Speaker 1: like you've got radio waves that's on the the longest 340 00:20:29,160 --> 00:20:33,119 Speaker 1: wavelength side of the electromagnetic spectrum, and then on the 341 00:20:33,200 --> 00:20:37,080 Speaker 1: opposite side, on the shortest wavelength side, you have gamma radiation. 342 00:20:37,800 --> 00:20:42,280 Speaker 1: So what determines the nature of this electromagnetism, what determines 343 00:20:42,320 --> 00:20:44,360 Speaker 1: what it can do and what we can use it for, 344 00:20:45,359 --> 00:20:48,800 Speaker 1: is its wavelength or its frequency. The two are related. 345 00:20:49,320 --> 00:20:53,080 Speaker 1: The longer the wavelength, the lower the frequency. The shorter 346 00:20:53,160 --> 00:20:55,720 Speaker 1: the wavelength, the higher the frequency. But here's the thing. 347 00:20:56,400 --> 00:21:00,440 Speaker 1: All of these frequencies are traveling at the same eat. 348 00:21:00,440 --> 00:21:03,880 Speaker 1: That electromagnetic speed is the speed of light, so they're 349 00:21:03,920 --> 00:21:07,040 Speaker 1: all traveling at the same speed. It's just that they 350 00:21:07,080 --> 00:21:11,040 Speaker 1: have different lengths of of waves, right. So radio waves 351 00:21:11,040 --> 00:21:15,159 Speaker 1: are very very very long, gamma waves are very very 352 00:21:15,280 --> 00:21:18,040 Speaker 1: very short. They both travel at the speed of light. 353 00:21:18,400 --> 00:21:20,800 Speaker 1: But it means that the number of waves that pass 354 00:21:20,880 --> 00:21:24,119 Speaker 1: you in a given second are very different for radio 355 00:21:24,160 --> 00:21:28,560 Speaker 1: than it is for gamma, because more of the gamma 356 00:21:28,640 --> 00:21:32,240 Speaker 1: can pass you in the second than the radio waves 357 00:21:32,280 --> 00:21:35,080 Speaker 1: because the length is so much shorter. Well, since visible 358 00:21:35,160 --> 00:21:39,200 Speaker 1: light occupies a range of frequencies, we can encounter some 359 00:21:39,320 --> 00:21:43,120 Speaker 1: challenges when we start to think about ways to manipulate light. 360 00:21:43,920 --> 00:21:49,280 Speaker 1: So there's this effect called chromatic aberration. Sometimes it's called 361 00:21:49,359 --> 00:21:53,320 Speaker 1: chromatic distortion, which be a great name for a band. 362 00:21:54,320 --> 00:21:59,359 Speaker 1: Maybe you just cover social distortion songs. Anyway, Chromatic distortion 363 00:21:59,400 --> 00:22:02,640 Speaker 1: occurs because visible light is made up of a band 364 00:22:03,160 --> 00:22:06,159 Speaker 1: of wave wavelengths of light. You know, red has the 365 00:22:06,240 --> 00:22:12,320 Speaker 1: longest wavelengths invisible light, Violet has the shortest wavelengths, and 366 00:22:12,359 --> 00:22:16,480 Speaker 1: when light hits a refractive surface like a lens, not 367 00:22:16,840 --> 00:22:20,240 Speaker 1: all these wavelengths are going to bend at quite the 368 00:22:20,359 --> 00:22:24,240 Speaker 1: same angle. So you might notice that some parts of 369 00:22:24,240 --> 00:22:28,160 Speaker 1: an image have little borders or fringes of color around them. 370 00:22:28,160 --> 00:22:32,040 Speaker 1: And that's because that wavelength of light, let's say it's red, 371 00:22:32,600 --> 00:22:35,800 Speaker 1: bent at a slightly different angle from the other wavelengths, 372 00:22:35,920 --> 00:22:39,480 Speaker 1: and so you get this kind of halo effect. Now, 373 00:22:39,480 --> 00:22:41,600 Speaker 1: the reason I bring this up is that one of 374 00:22:41,640 --> 00:22:45,040 Speaker 1: the biggest challenges when it comes to creating invisibility technology 375 00:22:45,640 --> 00:22:49,400 Speaker 1: is that the methods we might use could work differently 376 00:22:49,720 --> 00:22:53,359 Speaker 1: with some parts of the visible light spectrum from others, 377 00:22:53,960 --> 00:22:56,240 Speaker 1: and you might end up with the technology that can 378 00:22:56,280 --> 00:23:01,600 Speaker 1: redirect certain parts of the visible spectrum in a specific way, 379 00:23:01,640 --> 00:23:05,320 Speaker 1: but not all of the visible spectrum. And that would 380 00:23:05,359 --> 00:23:07,600 Speaker 1: mean that you would still be able to see the 381 00:23:07,640 --> 00:23:10,639 Speaker 1: cloak or the cloaked object, but it would look kind 382 00:23:10,640 --> 00:23:12,720 Speaker 1: of funny because you wouldn't see all the colors you 383 00:23:12,800 --> 00:23:15,200 Speaker 1: normally would, or it would appear to be a different 384 00:23:15,200 --> 00:23:19,600 Speaker 1: color than what it quote unquote really is. If you 385 00:23:19,640 --> 00:23:22,000 Speaker 1: want to think about another way, imagine that you've got 386 00:23:22,000 --> 00:23:25,120 Speaker 1: a gap that's just wide enough to let visible light 387 00:23:25,200 --> 00:23:29,560 Speaker 1: from green to violet go through. So anything that's green 388 00:23:29,640 --> 00:23:32,280 Speaker 1: to violet and the visible spectrum can pass through this 389 00:23:32,400 --> 00:23:36,119 Speaker 1: tiny little gap. But that would mean that wavelengths that 390 00:23:36,200 --> 00:23:38,960 Speaker 1: were in red, orange, and yellow light because of roy 391 00:23:39,040 --> 00:23:43,560 Speaker 1: g BIV, those wavelengths would bounce off because the gap 392 00:23:43,680 --> 00:23:47,840 Speaker 1: is too small for these wavelengths to pass through it. 393 00:23:47,840 --> 00:23:50,400 Speaker 1: It's it's too narrow. That's kind of what I'm going 394 00:23:50,480 --> 00:23:54,239 Speaker 1: with here, all right, So when we come back, we're 395 00:23:54,280 --> 00:23:56,560 Speaker 1: going to talk about some of the technology is meant 396 00:23:56,560 --> 00:24:01,080 Speaker 1: to make something invisible, and we're gonna start with stealth 397 00:24:01,400 --> 00:24:15,320 Speaker 1: technology after we take this quick break. All right. I'm 398 00:24:15,359 --> 00:24:18,159 Speaker 1: I'm a kid of the seventies and eights, and I 399 00:24:18,240 --> 00:24:23,240 Speaker 1: remember when the stealth bomber was becoming big news. It 400 00:24:23,320 --> 00:24:27,080 Speaker 1: was such a cool science fiction technology. We had heard 401 00:24:27,080 --> 00:24:30,639 Speaker 1: about things like cloaking devices and stuff, but here was 402 00:24:30,680 --> 00:24:34,640 Speaker 1: a plane that could at least what we were told 403 00:24:34,920 --> 00:24:40,040 Speaker 1: passed invisibly for radar systems. So clearly stealth technology, like 404 00:24:40,080 --> 00:24:44,480 Speaker 1: the famous stealth bomber, you know, is not invisible to 405 00:24:44,520 --> 00:24:47,080 Speaker 1: the naked eye. We can see it. It's not like 406 00:24:47,160 --> 00:24:50,359 Speaker 1: it's Wonder Woman's invisible jet here. So we're talking about 407 00:24:50,359 --> 00:24:53,560 Speaker 1: a vehicle that won't show up on radar, but we 408 00:24:53,600 --> 00:24:57,080 Speaker 1: can still see it. That's because radar is operating in 409 00:24:57,080 --> 00:25:01,600 Speaker 1: a different band of frequencies in the electromagnetic spectrum then 410 00:25:01,800 --> 00:25:07,240 Speaker 1: visible light. Right, So if there's something in a direction, 411 00:25:07,280 --> 00:25:10,320 Speaker 1: you've got a radar emitter. The radar emitter is shooting 412 00:25:10,320 --> 00:25:14,479 Speaker 1: out electromagnetic waves, and if that something is there, some 413 00:25:14,560 --> 00:25:16,639 Speaker 1: of those waves are going to hit that something and 414 00:25:16,760 --> 00:25:20,359 Speaker 1: bounce back. So if in addition to the emitter. You 415 00:25:20,400 --> 00:25:24,680 Speaker 1: have a detector that can detect the echoes of these 416 00:25:25,440 --> 00:25:29,800 Speaker 1: electromagnetic waves you've sent out, then you know, hey, there's 417 00:25:29,840 --> 00:25:33,000 Speaker 1: something there, right, And if you actually measure the difference 418 00:25:33,000 --> 00:25:36,000 Speaker 1: in time it took for the waves to go out 419 00:25:36,240 --> 00:25:38,919 Speaker 1: and then bounce back, you know how far away it 420 00:25:39,040 --> 00:25:42,680 Speaker 1: is because you know how fast those electromagnetic waves are traveling. 421 00:25:43,280 --> 00:25:46,000 Speaker 1: So you measure the amount of time it took for 422 00:25:46,040 --> 00:25:48,560 Speaker 1: the waves to go out and bounce back, that tells 423 00:25:48,560 --> 00:25:53,320 Speaker 1: you how far away the object is. You also can 424 00:25:53,320 --> 00:25:55,560 Speaker 1: figure out whether or not the object is moving towards 425 00:25:55,640 --> 00:25:58,120 Speaker 1: you or moving away from you because of the old 426 00:25:58,160 --> 00:26:02,320 Speaker 1: Doppler effect. So if the object is moving away from you, 427 00:26:02,640 --> 00:26:06,040 Speaker 1: the returning waves will actually be longer than what you 428 00:26:06,320 --> 00:26:10,120 Speaker 1: sent out toward it. If it is moving towards you, 429 00:26:10,480 --> 00:26:13,520 Speaker 1: then the returning waves are going to be shorter than 430 00:26:13,560 --> 00:26:19,000 Speaker 1: what you sent out, and the amount of elongation or 431 00:26:19,320 --> 00:26:23,160 Speaker 1: shortening would tell you how quickly this thing is traveling. 432 00:26:23,840 --> 00:26:26,640 Speaker 1: So it's really interesting, like that's that Doppler effect also 433 00:26:26,760 --> 00:26:28,800 Speaker 1: very important to what we're going to talk about in 434 00:26:28,880 --> 00:26:31,440 Speaker 1: just a bit. So let's say that you wanted to 435 00:26:31,520 --> 00:26:35,800 Speaker 1: create an aircraft that could go undetected by radar. What 436 00:26:35,920 --> 00:26:39,480 Speaker 1: do you do well, You probably use a combination of strategies. 437 00:26:39,800 --> 00:26:43,640 Speaker 1: So you might use some materials that can absorb electromagnetic 438 00:26:43,640 --> 00:26:47,399 Speaker 1: waves in the frequencies that are being used by radar, 439 00:26:47,800 --> 00:26:50,560 Speaker 1: so that way, when the wave hits the aircraft, the 440 00:26:50,600 --> 00:26:54,600 Speaker 1: aircraft absorbs that energy and there's not enough to echo 441 00:26:54,680 --> 00:26:57,960 Speaker 1: back to the detector, so it just it just gets 442 00:26:58,160 --> 00:27:02,280 Speaker 1: swallowed up. This would be kind of that super black 443 00:27:02,400 --> 00:27:06,760 Speaker 1: paint we were talking about earlier, where it absorbs most 444 00:27:06,800 --> 00:27:08,760 Speaker 1: of the visible light. In this case, it would be 445 00:27:08,800 --> 00:27:13,440 Speaker 1: absorbing the radar electromagnetic energy. But you probably all start 446 00:27:13,560 --> 00:27:16,760 Speaker 1: going to play a bit with reflection, and you do 447 00:27:16,840 --> 00:27:21,560 Speaker 1: this by designing your aircraft's exterior with these funky angles 448 00:27:21,600 --> 00:27:24,600 Speaker 1: on them, so that if a radar beam does hit 449 00:27:24,680 --> 00:27:28,479 Speaker 1: the aircraft, it gets reflected in an odd direction because 450 00:27:28,480 --> 00:27:31,639 Speaker 1: of that angle that it hits. You know, the angle 451 00:27:31,720 --> 00:27:34,919 Speaker 1: of incidents where the wave hits the aircraft means that 452 00:27:34,960 --> 00:27:37,120 Speaker 1: it's going to get reflected off in a direction where 453 00:27:37,240 --> 00:27:40,679 Speaker 1: hopefully there's no detector, so no one can see that 454 00:27:40,720 --> 00:27:43,879 Speaker 1: there's an aircraft there. This combination of strategies makes it 455 00:27:44,000 --> 00:27:48,120 Speaker 1: very difficult for radar stations to detect stealth aircraft, though 456 00:27:48,160 --> 00:27:51,600 Speaker 1: again the aircraft itself itself is still totally visible to 457 00:27:51,800 --> 00:27:56,160 Speaker 1: us because it's not redirecting or absorbing visible light. It's 458 00:27:56,200 --> 00:28:00,760 Speaker 1: doing it in say the microwave range. Over time, as 459 00:28:00,800 --> 00:28:06,560 Speaker 1: scientists develop new approaches to manipulating, absorbing, and reflecting electromagnetic radiation, 460 00:28:07,280 --> 00:28:10,160 Speaker 1: we would find ways to make objects quote unquote invisible 461 00:28:10,200 --> 00:28:14,080 Speaker 1: to specific kinds of electromagnetic frequencies. But it's a very 462 00:28:14,119 --> 00:28:17,199 Speaker 1: different thing to make an object undetectable from say a 463 00:28:17,320 --> 00:28:21,760 Speaker 1: microwave a mitter, than it is for visible light. Now, 464 00:28:22,040 --> 00:28:26,080 Speaker 1: imagine for a moment that you could redirect light around 465 00:28:26,119 --> 00:28:30,440 Speaker 1: an object, so the light would curve around an object, 466 00:28:30,840 --> 00:28:33,120 Speaker 1: move around to the other side, and then continue on 467 00:28:33,200 --> 00:28:35,720 Speaker 1: as if there were no object for the light to 468 00:28:35,720 --> 00:28:41,000 Speaker 1: interact with at all. So it's not passing through whatever 469 00:28:41,200 --> 00:28:44,800 Speaker 1: is cloaked, it's just going around whatever is quoaked and 470 00:28:44,800 --> 00:28:48,440 Speaker 1: then getting back on track. Then an outside observer would 471 00:28:48,480 --> 00:28:51,680 Speaker 1: not see anything there, right, They just look and it 472 00:28:51,680 --> 00:28:54,560 Speaker 1: would just look like empty space. You'd be looking at 473 00:28:54,600 --> 00:28:57,360 Speaker 1: everything that's on the other side of the object from 474 00:28:57,440 --> 00:28:59,560 Speaker 1: your point of view, and that would be it. That 475 00:28:59,600 --> 00:29:02,800 Speaker 1: would be really cool. Also would be very tricky because 476 00:29:02,800 --> 00:29:05,360 Speaker 1: if you're making all the light curve around the object, 477 00:29:05,400 --> 00:29:09,040 Speaker 1: and I'm saying all the light that's coming curves around it, 478 00:29:09,560 --> 00:29:12,400 Speaker 1: that means inside you wouldn't be able to see anything. 479 00:29:12,480 --> 00:29:16,360 Speaker 1: It would be perfectly dark because all light that's coming 480 00:29:16,400 --> 00:29:20,200 Speaker 1: to you has been redirected. So let's say that it's 481 00:29:20,240 --> 00:29:22,720 Speaker 1: like a small structure and you're inside it. It would 482 00:29:22,720 --> 00:29:27,320 Speaker 1: be completely dark inside that structure because all the incoming 483 00:29:27,400 --> 00:29:31,920 Speaker 1: light has been redirected. You could potentially light something inside 484 00:29:31,920 --> 00:29:34,560 Speaker 1: the structure and thus be able to see And if 485 00:29:34,560 --> 00:29:36,840 Speaker 1: the structure is not allowing light to pass back out, 486 00:29:37,600 --> 00:29:39,640 Speaker 1: then you'd be able to see inside, but you wouldn't 487 00:29:39,640 --> 00:29:41,840 Speaker 1: be able to see the outside world. Nothing in the 488 00:29:41,880 --> 00:29:43,680 Speaker 1: outside world would be visible to you because all that 489 00:29:43,760 --> 00:29:46,600 Speaker 1: light has been redirected. You would have to have a 490 00:29:46,680 --> 00:29:49,360 Speaker 1: way to allow some of the light from the exterior 491 00:29:49,400 --> 00:29:52,840 Speaker 1: world to come through, but still pass enough of the 492 00:29:52,920 --> 00:29:56,440 Speaker 1: light around so that an outside observer would be unaware 493 00:29:56,440 --> 00:30:00,400 Speaker 1: there was something there. That's super duper tricky. It's one 494 00:30:00,440 --> 00:30:04,080 Speaker 1: of the hardest parts of the cloaking device, one of 495 00:30:04,440 --> 00:30:07,520 Speaker 1: not the only so wicked hard to do. As it 496 00:30:07,560 --> 00:30:10,280 Speaker 1: turns out, now we've seen some fun approaches this kind 497 00:30:10,760 --> 00:30:14,960 Speaker 1: of a thing that that do succeed in certain frequencies 498 00:30:15,000 --> 00:30:18,840 Speaker 1: like the microwave range. Uh. And we've also seen some 499 00:30:18,960 --> 00:30:22,760 Speaker 1: fun ways to simulate a cloaking device, but it's not 500 00:30:22,800 --> 00:30:25,800 Speaker 1: actually a cloaking device. For example, a fun one I 501 00:30:25,840 --> 00:30:29,920 Speaker 1: have seen is a screen mounted on say the side 502 00:30:29,920 --> 00:30:32,920 Speaker 1: of a truck, like like a semi truck or something 503 00:30:32,920 --> 00:30:36,320 Speaker 1: along those lines, And you've got a screen on one 504 00:30:36,360 --> 00:30:38,720 Speaker 1: side of display, and on the opposite side of the 505 00:30:38,720 --> 00:30:41,760 Speaker 1: truck you have cameras mounted to capture a live feed 506 00:30:41,840 --> 00:30:43,880 Speaker 1: of whatever is on the other side of the truck, 507 00:30:44,520 --> 00:30:47,840 Speaker 1: and then it feeds that live feed to the screen 508 00:30:47,920 --> 00:30:51,360 Speaker 1: that's mounted on the side, So the truck is totally solid. 509 00:30:51,560 --> 00:30:54,880 Speaker 1: Light is not passing through it or going around it. Instead, 510 00:30:55,760 --> 00:30:58,360 Speaker 1: you're just looking at a video feed on whatever is 511 00:30:58,400 --> 00:31:01,320 Speaker 1: the other side displayed on the truck ruck. And I've 512 00:31:01,360 --> 00:31:03,680 Speaker 1: seen this sort of thing at various events where it's 513 00:31:03,720 --> 00:31:05,920 Speaker 1: just kind of fun, like you can actually see people 514 00:31:05,960 --> 00:31:08,440 Speaker 1: walking on the opposite side of the truck, but it's 515 00:31:08,440 --> 00:31:11,520 Speaker 1: because they're being displayed on this screen. It's not that 516 00:31:11,560 --> 00:31:15,880 Speaker 1: the truck is actually transparent or has magically disappeared, and 517 00:31:15,880 --> 00:31:18,920 Speaker 1: it's a fun effect, or it can be, but it's 518 00:31:19,200 --> 00:31:22,040 Speaker 1: very limited and you know exactly what's happening, right, It's 519 00:31:22,040 --> 00:31:25,600 Speaker 1: not like it's mysterious. Now. I have seen this incorporated 520 00:31:25,600 --> 00:31:27,760 Speaker 1: into costumes in a way that was kind of fun. 521 00:31:28,760 --> 00:31:31,520 Speaker 1: I saw a guy in a zombie costume once where 522 00:31:31,640 --> 00:31:36,040 Speaker 1: he had mounted a tablet inside his costume in the front, 523 00:31:36,800 --> 00:31:39,920 Speaker 1: and he was had a camera mounted on his back 524 00:31:40,720 --> 00:31:43,560 Speaker 1: and it was feeding live video from the camera on 525 00:31:43,600 --> 00:31:46,320 Speaker 1: the back to the tablet so that it looked like 526 00:31:46,320 --> 00:31:49,040 Speaker 1: there was a hole in his torso. Like his torso 527 00:31:49,120 --> 00:31:51,960 Speaker 1: just said this fist shaped hole all the way through, 528 00:31:52,680 --> 00:31:56,040 Speaker 1: and that you can see video from the opposite side 529 00:31:56,480 --> 00:31:59,320 Speaker 1: feeding through on the tablet, which was effective if you're 530 00:31:59,320 --> 00:32:01,239 Speaker 1: looking at him at on. If you're looking at them 531 00:32:01,280 --> 00:32:03,680 Speaker 1: from an angle, it didn't work so well, but it 532 00:32:03,760 --> 00:32:08,400 Speaker 1: was a really clever use of this particular approach. Still 533 00:32:08,560 --> 00:32:11,800 Speaker 1: not really a cloaking device. Right. To get into the 534 00:32:11,800 --> 00:32:15,280 Speaker 1: possibility of actually bending light around an object, we have 535 00:32:15,320 --> 00:32:18,400 Speaker 1: to talk about some really advanced technology, and I'm talking 536 00:32:18,440 --> 00:32:23,720 Speaker 1: about stuff like meta materials and nanotechnology. So first up 537 00:32:23,880 --> 00:32:27,280 Speaker 1: is meta material. What the heck is a meta material? 538 00:32:28,720 --> 00:32:32,480 Speaker 1: I've never met a material I didn't like, No. Essentially, 539 00:32:33,000 --> 00:32:35,560 Speaker 1: a meta material is an artificial material, so you're not 540 00:32:35,600 --> 00:32:38,120 Speaker 1: going to find this in nature. It's not naturally occurring, 541 00:32:38,840 --> 00:32:42,600 Speaker 1: and it's a material that has electromagnetic properties that other 542 00:32:42,680 --> 00:32:46,560 Speaker 1: materials in nature do not have, which can include stuff 543 00:32:46,600 --> 00:32:51,000 Speaker 1: like redirecting electromagnetic waves in a way that just doesn't 544 00:32:51,000 --> 00:32:54,880 Speaker 1: occur in nature, and that can even include light. So 545 00:32:55,920 --> 00:32:59,200 Speaker 1: in the nineteen sixties there was this scientist named Victor 546 00:32:59,400 --> 00:33:04,160 Speaker 1: Veselogue who hypothesized way back in sixty eight that it 547 00:33:04,240 --> 00:33:08,479 Speaker 1: should be possible to have a material that could have 548 00:33:08,640 --> 00:33:14,520 Speaker 1: a negative refractive index. Okay, wait, what does that mean? 549 00:33:14,600 --> 00:33:17,440 Speaker 1: All right, So again, remember we talked about this earlier 550 00:33:17,480 --> 00:33:22,520 Speaker 1: with refraction. When light passes from one medium into another medium, 551 00:33:22,560 --> 00:33:26,760 Speaker 1: the path of that light will change because light traveling 552 00:33:26,800 --> 00:33:29,640 Speaker 1: through the air and then hitting the water will change 553 00:33:29,680 --> 00:33:32,320 Speaker 1: because the speed of light itself changes as it goes 554 00:33:32,320 --> 00:33:37,280 Speaker 1: from medium to medium. So that we all understand, and 555 00:33:37,400 --> 00:33:40,480 Speaker 1: again that's due to the differences in the refractive indices 556 00:33:40,520 --> 00:33:44,400 Speaker 1: of these two medium air has wa refractive index essentially one, 557 00:33:45,040 --> 00:33:48,440 Speaker 1: and clear water would have another like one point three three. 558 00:33:49,160 --> 00:33:51,880 Speaker 1: The bigger the difference between these two indices, the more 559 00:33:51,960 --> 00:33:53,600 Speaker 1: dramatic the angle is going to be. And in the 560 00:33:53,680 --> 00:33:57,080 Speaker 1: natural world, we would describe all these indices as having 561 00:33:57,240 --> 00:34:01,880 Speaker 1: a positive value. But what would happen if you created 562 00:34:02,000 --> 00:34:06,240 Speaker 1: a material that had a negative refractive index, so that 563 00:34:06,320 --> 00:34:09,200 Speaker 1: the light bent in a different way, like it bent 564 00:34:09,239 --> 00:34:11,720 Speaker 1: at a negative angle as opposed to a positive angle. 565 00:34:12,560 --> 00:34:15,520 Speaker 1: Thes A lago suggested that such a material is entirely 566 00:34:15,560 --> 00:34:18,880 Speaker 1: possible without violating the laws of physics, which is a 567 00:34:18,880 --> 00:34:21,160 Speaker 1: good thing because violating those kinds of laws will really 568 00:34:21,160 --> 00:34:24,120 Speaker 1: get into heaps of trouble. But more seriously, admit that 569 00:34:24,160 --> 00:34:27,400 Speaker 1: while such materials don't exist in nature, it should be 570 00:34:27,520 --> 00:34:30,680 Speaker 1: possible to create that kind of material, or at least 571 00:34:31,520 --> 00:34:33,719 Speaker 1: the material itself does not go against the rules of 572 00:34:33,760 --> 00:34:35,799 Speaker 1: the universe, even if we never figured out how to 573 00:34:35,920 --> 00:34:40,280 Speaker 1: make the darned stuff. As a Lagos said, such material 574 00:34:40,600 --> 00:34:44,840 Speaker 1: would behave oddly when exposed to electromagnetic waves, at least 575 00:34:45,160 --> 00:34:49,680 Speaker 1: waves at specific frequencies. Because it would probably be impossible 576 00:34:49,760 --> 00:34:53,240 Speaker 1: to make a material that could interact across the entire 577 00:34:53,320 --> 00:34:57,600 Speaker 1: electro magnetic spectrum in a specific way. You could do 578 00:34:57,719 --> 00:35:01,440 Speaker 1: it in chunks of the electro agnetic spectrum, because again 579 00:35:01,880 --> 00:35:08,200 Speaker 1: that spectrum covers a huge range of wavelengths. So the materials, 580 00:35:08,280 --> 00:35:12,680 Speaker 1: composite parts, the cells that make up this material would 581 00:35:12,719 --> 00:35:17,920 Speaker 1: determine which frequencies in the electromagnetic spectrum would behave differently 582 00:35:17,960 --> 00:35:21,760 Speaker 1: when interacting with this stuff, and specifically those materials, those cells, 583 00:35:21,760 --> 00:35:24,640 Speaker 1: those components would have to be the same size or 584 00:35:24,800 --> 00:35:30,439 Speaker 1: smaller than the wavelengths you were looking to manipulate. So 585 00:35:30,640 --> 00:35:34,840 Speaker 1: as you get further into the electromagnetic spectrum, those components 586 00:35:34,880 --> 00:35:37,200 Speaker 1: have to get tinier and tinier. You get down to 587 00:35:37,239 --> 00:35:39,880 Speaker 1: the microscopic level, and then you blow that out of 588 00:35:39,880 --> 00:35:42,400 Speaker 1: the water and you get even smaller, because if you 589 00:35:42,440 --> 00:35:45,080 Speaker 1: want to get down to the visible spectrum, you have 590 00:35:45,160 --> 00:35:49,200 Speaker 1: to be at the nanoscale. A nanometer is one billionth 591 00:35:49,200 --> 00:35:52,560 Speaker 1: of a meter and at that scale things get wacky. 592 00:35:53,160 --> 00:35:56,120 Speaker 1: As for what you would make this material out of, well, 593 00:35:56,120 --> 00:35:58,759 Speaker 1: that could be conventional stuff. It wouldn't have to be 594 00:35:58,800 --> 00:36:02,960 Speaker 1: anything true the exotic. The material itself could be made 595 00:36:03,000 --> 00:36:07,000 Speaker 1: up of metals or plastics, all sorts of stuff. The 596 00:36:07,040 --> 00:36:09,960 Speaker 1: important part would be the various cells would be the 597 00:36:09,960 --> 00:36:15,840 Speaker 1: correct size, orientation, shape, et cetera, in order to achieve 598 00:36:15,960 --> 00:36:20,960 Speaker 1: whatever goal you set out to make. So that's what 599 00:36:21,000 --> 00:36:24,279 Speaker 1: would affect the electromagnetic waves in different ways more than 600 00:36:24,320 --> 00:36:28,359 Speaker 1: the material itself. It's interesting because we often think of 601 00:36:29,400 --> 00:36:35,520 Speaker 1: creating specific effects by going with a particular chemical composition 602 00:36:35,640 --> 00:36:39,360 Speaker 1: of materials. Right, Like copper is a very good electric conductor, 603 00:36:39,520 --> 00:36:43,239 Speaker 1: for example, so we often think of copper in the 604 00:36:43,360 --> 00:36:46,799 Speaker 1: term in terms of things like wiring. There are other 605 00:36:47,080 --> 00:36:49,680 Speaker 1: materials that are actually better conductors than copper, but they 606 00:36:49,719 --> 00:36:53,640 Speaker 1: also get more rare and more expensive, so copper was 607 00:36:53,680 --> 00:36:56,960 Speaker 1: kind of what we went with. Well, what Vesi Lago 608 00:36:57,040 --> 00:37:00,000 Speaker 1: is saying is that we wouldn't so much be considered 609 00:37:00,080 --> 00:37:04,520 Speaker 1: in the atomic nature of the material as opposed to 610 00:37:05,000 --> 00:37:09,440 Speaker 1: the physical structure of that material, like how small or 611 00:37:09,440 --> 00:37:11,920 Speaker 1: how large it is, what shape it is, and how 612 00:37:12,480 --> 00:37:16,839 Speaker 1: it is arranged geometrically, and what or what's orientation is 613 00:37:16,880 --> 00:37:21,080 Speaker 1: with respect to the incoming electromagnetic radiation. That's what's important, 614 00:37:21,120 --> 00:37:26,839 Speaker 1: the physical actual arrangement of this material, which is really 615 00:37:26,880 --> 00:37:31,440 Speaker 1: interesting way of thinking about things. Now, remember the Doppler 616 00:37:31,480 --> 00:37:34,719 Speaker 1: effect that I mentioned earlier. Vezi Lago said that with 617 00:37:34,760 --> 00:37:38,080 Speaker 1: the right negative refractive index, a material could produce a 618 00:37:38,160 --> 00:37:44,279 Speaker 1: reverse Doppler shift. That's crazy, right, So let's say that 619 00:37:44,360 --> 00:37:47,120 Speaker 1: you had a stealth plane that was coded with this 620 00:37:47,239 --> 00:37:51,640 Speaker 1: kind of stuff, and instead of trying to absorb or 621 00:37:51,680 --> 00:37:57,040 Speaker 1: redirect radar uh energy like the electromagetic waves that a 622 00:37:57,080 --> 00:38:01,120 Speaker 1: is being sent out by radar. Instead, what's doing is 623 00:38:01,200 --> 00:38:05,520 Speaker 1: reversing the Doppler shift. So that way, if this plane 624 00:38:05,560 --> 00:38:09,920 Speaker 1: were approaching you, the reading you would get would indicate 625 00:38:09,920 --> 00:38:11,600 Speaker 1: to you that, oh, there is an object there, but 626 00:38:11,640 --> 00:38:14,840 Speaker 1: it's moving away, Whereas if the plane we're flying away, 627 00:38:15,280 --> 00:38:17,120 Speaker 1: you'd look at and say, oh, there's an object that's 628 00:38:17,120 --> 00:38:22,160 Speaker 1: coming toward us, because the dopplership would be reversed. This 629 00:38:22,239 --> 00:38:25,319 Speaker 1: is hard for me to wrap my head around the 630 00:38:25,440 --> 00:38:30,840 Speaker 1: idea that this material would interact with electromagnetic radiation in 631 00:38:30,880 --> 00:38:34,359 Speaker 1: such a way as to create a result that's counterintuitive. 632 00:38:35,000 --> 00:38:37,160 Speaker 1: It doesn't go the same way as what we're used 633 00:38:37,200 --> 00:38:40,319 Speaker 1: to because again, this material doesn't appear in nature. If 634 00:38:40,320 --> 00:38:43,839 Speaker 1: it did, then we wouldn't find it counterintuitive at all. 635 00:38:43,880 --> 00:38:46,800 Speaker 1: We just say like, oh, that's this material as opposed 636 00:38:46,840 --> 00:38:49,560 Speaker 1: to that material. But because it doesn't appear in nature, 637 00:38:49,560 --> 00:38:52,600 Speaker 1: we don't really think about this stuff. We don't encounter 638 00:38:52,680 --> 00:38:57,000 Speaker 1: it really interesting. However, now, when vessel Lago said all this, 639 00:38:57,080 --> 00:38:59,520 Speaker 1: it was all purely in the hypothetical realm. He said, 640 00:38:59,520 --> 00:39:03,239 Speaker 1: there's no reason why this could not exist, but we 641 00:39:03,280 --> 00:39:06,919 Speaker 1: didn't have a way of making it. Things are different now. 642 00:39:07,080 --> 00:39:11,400 Speaker 1: Starting around the early two thousand's, scientists started to experiment 643 00:39:11,840 --> 00:39:15,200 Speaker 1: in trying to create meta materials, and in fact we're 644 00:39:15,239 --> 00:39:19,080 Speaker 1: starting to be successful, specifically for things like in the 645 00:39:19,160 --> 00:39:23,839 Speaker 1: microwave range of electromagnetic radiation, so that scientists were able 646 00:39:23,880 --> 00:39:28,479 Speaker 1: to create a cloaking device for the microwave range, where 647 00:39:28,560 --> 00:39:31,760 Speaker 1: they were able to put a little cylinder in the 648 00:39:31,800 --> 00:39:35,640 Speaker 1: path of a microwave beam and use this meta material 649 00:39:35,719 --> 00:39:39,680 Speaker 1: stuff to redirect the microwaves so that the microwaves passed 650 00:39:39,760 --> 00:39:44,080 Speaker 1: around the cylinder and continued on as if nothing were there. 651 00:39:44,480 --> 00:39:49,560 Speaker 1: So to the microwave detector, there was nothing in its path. Fascinating, 652 00:39:49,640 --> 00:39:52,480 Speaker 1: but again, doesn't work for the visible light spectrum. Right 653 00:39:52,480 --> 00:39:54,719 Speaker 1: if we were to look, we'd see, okay, the cylinders 654 00:39:54,719 --> 00:39:59,319 Speaker 1: still there, because the cloaking device only effects radiation in 655 00:39:59,320 --> 00:40:04,440 Speaker 1: the microwave range of wavelengths. So to get the visible 656 00:40:04,520 --> 00:40:07,640 Speaker 1: light version of this, we have to reduce the size 657 00:40:07,680 --> 00:40:11,520 Speaker 1: of all those components within the meta materials, because microwaves 658 00:40:11,520 --> 00:40:15,319 Speaker 1: are small, but they're not in the nanoscale small like 659 00:40:15,719 --> 00:40:18,919 Speaker 1: the visible light spectrum is the other side of that. 660 00:40:19,239 --> 00:40:21,400 Speaker 1: Is kind of like when I was talking with chromatic 661 00:40:21,440 --> 00:40:26,160 Speaker 1: aberration earlier. Visible light spectrum that's made up of a 662 00:40:26,440 --> 00:40:30,680 Speaker 1: range of wavelengths. Right, the red wavelengths are longer than 663 00:40:30,719 --> 00:40:34,520 Speaker 1: the violet wavelengths are on the other side of the spectrum. 664 00:40:34,600 --> 00:40:38,680 Speaker 1: So it's hard to find materials and a size and 665 00:40:38,760 --> 00:40:42,080 Speaker 1: orientation that will work with the entire range of visible light, 666 00:40:43,200 --> 00:40:46,640 Speaker 1: which means it's hard to create a cloaking device that 667 00:40:46,680 --> 00:40:50,360 Speaker 1: can work for all light as opposed to just part 668 00:40:50,440 --> 00:40:54,040 Speaker 1: of the spectrum. So even if we get everything down 669 00:40:54,080 --> 00:40:57,239 Speaker 1: to the correct size, we might find it difficult to 670 00:40:57,360 --> 00:41:00,680 Speaker 1: cloak stuff effectively across the entire visible action, which might 671 00:41:00,680 --> 00:41:05,680 Speaker 1: mean that we just end up with very oddly colored stuff. Also, 672 00:41:05,760 --> 00:41:07,239 Speaker 1: we have to remember that when you get down to 673 00:41:07,239 --> 00:41:11,440 Speaker 1: the nano scale, things behave differently like the stuff that 674 00:41:11,480 --> 00:41:15,160 Speaker 1: we're used to at the macro scale at the classic 675 00:41:15,239 --> 00:41:18,239 Speaker 1: scale of physics start to break down when you get 676 00:41:18,320 --> 00:41:24,000 Speaker 1: down to the nano scale. For example, gold gold is gold, 677 00:41:24,160 --> 00:41:26,240 Speaker 1: right like when you look at gold, it's a gold color. 678 00:41:26,280 --> 00:41:31,040 Speaker 1: It's shiny, yellowish gold color. When you break down gold 679 00:41:31,080 --> 00:41:35,480 Speaker 1: down to nanoparticles, It actually, depending on its size, will 680 00:41:35,480 --> 00:41:39,400 Speaker 1: start to reflect light at different wavelengths. So you can 681 00:41:39,440 --> 00:41:42,520 Speaker 1: have gold particles that look red or gold particles that 682 00:41:42,560 --> 00:41:46,240 Speaker 1: look blue, which is weird to say, like, yes, it's gold, 683 00:41:46,239 --> 00:41:49,719 Speaker 1: but it's red. Now, you you're kind of confusing me 684 00:41:49,760 --> 00:41:51,880 Speaker 1: because we've used the same word to describe both the 685 00:41:51,920 --> 00:41:55,239 Speaker 1: color and the material itself. It's like an orange, right, 686 00:41:55,680 --> 00:41:59,080 Speaker 1: if an orange were purple, but we still call it 687 00:41:59,080 --> 00:42:02,480 Speaker 1: it an orange. It probably wrinkle your brain a little bit, 688 00:42:03,200 --> 00:42:06,160 Speaker 1: or at least the wrinkles my brain. I mean, I'm 689 00:42:06,160 --> 00:42:09,880 Speaker 1: a simple person, so that's why it gets to me. 690 00:42:10,000 --> 00:42:12,640 Speaker 1: But the idea of like, at the nano scale, gold 691 00:42:12,680 --> 00:42:16,279 Speaker 1: could be red or blue is weird. It also means 692 00:42:16,320 --> 00:42:18,919 Speaker 1: that when we started getting down there, it may mean, yeah, 693 00:42:18,960 --> 00:42:23,160 Speaker 1: we figured out the the right size and the right 694 00:42:23,239 --> 00:42:26,200 Speaker 1: orientation for all these particles to redirect light. However, once 695 00:42:26,239 --> 00:42:29,239 Speaker 1: we get the elements down to the nano scale, there 696 00:42:29,239 --> 00:42:32,680 Speaker 1: are other properties that emerge that we did not anticipate, 697 00:42:33,000 --> 00:42:35,279 Speaker 1: and that's going to make it even more difficult. So 698 00:42:35,680 --> 00:42:41,120 Speaker 1: there are lots of challenges here. More than that, we 699 00:42:41,200 --> 00:42:45,680 Speaker 1: may just find that we cannot create a practical cloaking 700 00:42:45,719 --> 00:42:50,080 Speaker 1: device that works across the visible spectrum um ever, at 701 00:42:50,160 --> 00:42:54,960 Speaker 1: least not anything that will work better than within specific 702 00:42:55,239 --> 00:42:59,840 Speaker 1: narrow use cases. There have been some demonstrations that in 703 00:43:00,800 --> 00:43:04,520 Speaker 1: uh conditions where there's some light scattering effects, that you 704 00:43:04,560 --> 00:43:07,960 Speaker 1: can actually have a really effective cloaking device, but that 705 00:43:08,080 --> 00:43:12,120 Speaker 1: requires other things to be in place, like fog or 706 00:43:12,239 --> 00:43:16,360 Speaker 1: missed that when you have something that's causing light to scatter, 707 00:43:17,120 --> 00:43:20,960 Speaker 1: it becomes easier to redirect certain light and make it 708 00:43:21,120 --> 00:43:24,520 Speaker 1: difficult to see something. You can effectively have an invisible 709 00:43:24,520 --> 00:43:28,240 Speaker 1: object in the space, but then you're also talking about 710 00:43:28,280 --> 00:43:31,880 Speaker 1: these other things that are impacting that You're already impacting 711 00:43:31,960 --> 00:43:39,200 Speaker 1: visibility at that point anyway, So it's got very limited utility. 712 00:43:39,920 --> 00:43:41,960 Speaker 1: Still really fascinating, and I'm not saying we're never going 713 00:43:42,040 --> 00:43:45,160 Speaker 1: to get there. I would never say that, because people 714 00:43:45,320 --> 00:43:49,000 Speaker 1: way way smarter than I am or working on these 715 00:43:49,080 --> 00:43:52,719 Speaker 1: kinds of technologies. Whether there's ever a practical use for it, 716 00:43:52,800 --> 00:43:57,000 Speaker 1: that's another question, because while you might be able to 717 00:43:57,040 --> 00:44:00,200 Speaker 1: create something that is invisible to the naked eye, you 718 00:44:00,239 --> 00:44:03,960 Speaker 1: would still end up having to factor in things like 719 00:44:04,560 --> 00:44:08,560 Speaker 1: radio waves, microwaves, all sorts of stuff, because again, not 720 00:44:08,600 --> 00:44:13,880 Speaker 1: all wavelengths are the same, and if it cannot manipulate 721 00:44:14,120 --> 00:44:19,920 Speaker 1: or warp these these incoming electromagnetic waves equally across the spectrum, 722 00:44:20,560 --> 00:44:23,879 Speaker 1: then it's going to be detectable by something. And also 723 00:44:23,920 --> 00:44:26,799 Speaker 1: you have to still fix that issue that if you 724 00:44:26,840 --> 00:44:29,719 Speaker 1: don't have a way of allowing at least some of 725 00:44:29,719 --> 00:44:34,640 Speaker 1: that light to pass into the cloaked area, it will 726 00:44:34,680 --> 00:44:39,560 Speaker 1: be pitch black inside the cloak because no light is 727 00:44:39,600 --> 00:44:43,080 Speaker 1: coming in. It's all being redirected around it. There are 728 00:44:43,080 --> 00:44:45,840 Speaker 1: other elements that you have to worry about. Two. I 729 00:44:45,840 --> 00:44:49,240 Speaker 1: didn't even get into things like phase shifting, largely because 730 00:44:49,320 --> 00:44:54,400 Speaker 1: I only have a limited understanding of it, and I 731 00:44:54,520 --> 00:44:57,960 Speaker 1: quickly get out of my element. And while I could 732 00:44:58,040 --> 00:45:01,480 Speaker 1: attempt to try and go down road, I would probably 733 00:45:01,560 --> 00:45:04,120 Speaker 1: steer us all the wrong way, and then I'd get 734 00:45:04,120 --> 00:45:07,000 Speaker 1: a lot of messages calling me out on that. And 735 00:45:07,120 --> 00:45:11,040 Speaker 1: rightfully so, even as it stands, I worry that I've 736 00:45:11,560 --> 00:45:16,440 Speaker 1: oversimplified things to a point where I'm being misleading. It 737 00:45:16,560 --> 00:45:21,239 Speaker 1: is difficult to break this down to a level that 738 00:45:21,400 --> 00:45:25,279 Speaker 1: I am comfortable communicating without feeling like, oh, I'm just 739 00:45:25,320 --> 00:45:27,920 Speaker 1: saying things, but I don't understand what I'm talking about 740 00:45:28,520 --> 00:45:30,600 Speaker 1: and that really comes down to the fact that I 741 00:45:30,640 --> 00:45:36,480 Speaker 1: haven't taken a science class in why like almost thirty years, 742 00:45:36,680 --> 00:45:42,560 Speaker 1: so I'm working on a lot of old brain cells 743 00:45:42,600 --> 00:45:44,719 Speaker 1: that are are grumpy that I've called on them for 744 00:45:44,760 --> 00:45:50,799 Speaker 1: this episode. Still fascinating stuff. And the demonstrations I have 745 00:45:51,000 --> 00:45:54,879 Speaker 1: seen even of the limited quote unquote invisibility where it's 746 00:45:54,880 --> 00:45:58,319 Speaker 1: not the visible spectrum but it's other ranges of the 747 00:45:58,320 --> 00:46:02,479 Speaker 1: electromagnic spectrum, They're amazing. And the idea that we can 748 00:46:02,480 --> 00:46:10,840 Speaker 1: create materials that have counterintuitive reactions to electromagnetic radiation is 749 00:46:10,920 --> 00:46:15,480 Speaker 1: incredibly fascinating. And there are some really cool applications beyond 750 00:46:16,120 --> 00:46:21,520 Speaker 1: the fantasy science fiction concept of invisibility, like completely transforming optics, 751 00:46:21,840 --> 00:46:25,600 Speaker 1: so that you could have, at least on one level, 752 00:46:25,920 --> 00:46:31,400 Speaker 1: a much simpler approach to optics where you have incredible effects, 753 00:46:31,400 --> 00:46:34,520 Speaker 1: but you've really reduced the complexity of the overall material, 754 00:46:34,880 --> 00:46:41,000 Speaker 1: the overall UH tool, for example, like a telescope, and 755 00:46:41,680 --> 00:46:44,360 Speaker 1: you were able to do that by using specific meta 756 00:46:44,400 --> 00:46:48,839 Speaker 1: materials like that, to me is truly amazing stuff. Being 757 00:46:48,840 --> 00:46:54,120 Speaker 1: able to reduce complexity and points of failure by engineering 758 00:46:54,160 --> 00:46:59,400 Speaker 1: material that just more effectively redirects or interacts with electromagnetic radiation. 759 00:47:00,320 --> 00:47:02,920 Speaker 1: That's mind blowing. Like to me, that is science fiction, 760 00:47:02,960 --> 00:47:05,719 Speaker 1: and yet it's stuff that's unfolding right now, and that's 761 00:47:05,719 --> 00:47:08,120 Speaker 1: why I think it is so cool. All Right, I'm 762 00:47:08,160 --> 00:47:11,920 Speaker 1: done geeking out about invisibility now, not really done, but 763 00:47:11,960 --> 00:47:15,640 Speaker 1: I'm done talking about it. So if you have suggestions 764 00:47:15,680 --> 00:47:18,960 Speaker 1: for topics I should cover. I've got a planned episode 765 00:47:18,960 --> 00:47:21,799 Speaker 1: coming up where we're gonna talk about the history of 766 00:47:21,880 --> 00:47:24,680 Speaker 1: spy balloons because obviously that's been in the news a 767 00:47:24,800 --> 00:47:27,439 Speaker 1: lot lately, so I want to talk about that because 768 00:47:27,480 --> 00:47:30,200 Speaker 1: that history stretches way back, y'all, and I want to 769 00:47:30,200 --> 00:47:34,320 Speaker 1: talk about like the early use and then the the 770 00:47:34,400 --> 00:47:38,000 Speaker 1: evolution of the technology and the use of such balloons 771 00:47:38,680 --> 00:47:41,080 Speaker 1: and look forward to that in the near future. If 772 00:47:41,120 --> 00:47:43,080 Speaker 1: you have other topics you would like me to tackle, 773 00:47:43,160 --> 00:47:45,160 Speaker 1: let me know. You can reach out on Twitter. The 774 00:47:45,200 --> 00:47:49,279 Speaker 1: handle for the show is tech Stuff hs W, or 775 00:47:49,640 --> 00:47:51,759 Speaker 1: you can download the I Heart radio app. It's breed 776 00:47:51,800 --> 00:47:54,359 Speaker 1: to download and use. You can navigate over to tech 777 00:47:54,360 --> 00:47:56,279 Speaker 1: Stuff by putting that into the little search field. It 778 00:47:56,280 --> 00:47:58,640 Speaker 1: will take your right to the page. You'll see there's 779 00:47:58,640 --> 00:48:00,839 Speaker 1: a little microphone icon there. Click on that you can 780 00:48:00,920 --> 00:48:03,160 Speaker 1: leave a voice message up to thirty seconds in length. 781 00:48:03,680 --> 00:48:05,280 Speaker 1: Let me know what you'd like to hear in the future, 782 00:48:05,719 --> 00:48:14,759 Speaker 1: and I'll talk to you again really soon. Yeah. Text 783 00:48:14,760 --> 00:48:18,239 Speaker 1: Stuff is an I Heart Radio production. For more podcasts 784 00:48:18,239 --> 00:48:21,000 Speaker 1: from my Heart Radio, visit the i Heart Radio app, 785 00:48:21,120 --> 00:48:24,280 Speaker 1: Apple Podcasts, or wherever you listen to your favorite shows.