1 00:00:08,480 --> 00:00:11,840 Speaker 1: Hey, Kelly, is there a superpower you see inviction that 2 00:00:11,960 --> 00:00:15,600 Speaker 1: you'd like to have like in real life? You know, 3 00:00:15,640 --> 00:00:17,720 Speaker 1: I think I'd like to be like the Flash, but 4 00:00:17,800 --> 00:00:19,920 Speaker 1: instead of running anywhere, because I'm not a big fan 5 00:00:19,960 --> 00:00:21,599 Speaker 1: of running, I want to get through my to do 6 00:00:21,800 --> 00:00:27,080 Speaker 1: list super fast. Well, the world is on pause. I 7 00:00:27,160 --> 00:00:30,280 Speaker 1: love it the Flash, but for paperwriting and parenting and 8 00:00:30,400 --> 00:00:35,160 Speaker 1: household errands. Yeah exactly. But you know, I don't think 9 00:00:35,200 --> 00:00:37,400 Speaker 1: a comic book about that would sell very well. To 10 00:00:37,440 --> 00:00:40,480 Speaker 1: be honest, I also don't think that technology is likely 11 00:00:40,520 --> 00:00:43,640 Speaker 1: to actually, you know, come to fruition. Really, you should 12 00:00:43,680 --> 00:00:45,760 Speaker 1: have more faith in scientists, Daniel, Well, I think the 13 00:00:45,800 --> 00:00:48,760 Speaker 1: problem is scientists already have too much to do, so 14 00:00:48,800 --> 00:00:51,520 Speaker 1: they don't have time to create the Flash technology. Yeah, 15 00:00:51,520 --> 00:00:53,440 Speaker 1: but once we have it, it'll be a snap to 16 00:00:53,520 --> 00:01:12,440 Speaker 1: reinvent it. Hi. I'm Daniel. I'm a particle physicist and 17 00:01:12,480 --> 00:01:16,600 Speaker 1: I have an infinitely long to do list. Hi. I'm Kelly. 18 00:01:16,640 --> 00:01:19,840 Speaker 1: I'm a parasitologist and I haven't infinitely long to do list. 19 00:01:19,880 --> 00:01:25,680 Speaker 1: Plus one and Welcome to the podcast. Daniel and Jorge 20 00:01:25,760 --> 00:01:28,920 Speaker 1: Explain the Universe, a production of I Heart Radio in 21 00:01:28,959 --> 00:01:32,360 Speaker 1: which we explore the infinity plus one things we'd all 22 00:01:32,520 --> 00:01:35,520 Speaker 1: like to understand about the universe. We take a tour 23 00:01:35,600 --> 00:01:38,399 Speaker 1: of everything that's amazing and crazy, from the inside of 24 00:01:38,440 --> 00:01:41,800 Speaker 1: neutron stars to the tiniest particles out there, and we 25 00:01:41,920 --> 00:01:44,840 Speaker 1: try to make sure you understand all of it. And 26 00:01:44,880 --> 00:01:46,920 Speaker 1: as you might have, guest Jorge is not joining us 27 00:01:46,920 --> 00:01:50,400 Speaker 1: to down the podcast, but we have a wonderful guest host, Kelly. 28 00:01:50,440 --> 00:01:53,680 Speaker 1: Would you introduce yourself? Sure? So, I'm Dr Kelly Weener Smith. 29 00:01:53,880 --> 00:01:57,400 Speaker 1: I am running a small ecology research site in central 30 00:01:57,480 --> 00:02:01,080 Speaker 1: Virginia and I'm adjunct with Race University and only study parasites. 31 00:02:01,120 --> 00:02:03,400 Speaker 1: But as my side job, I co author books with 32 00:02:03,400 --> 00:02:05,720 Speaker 1: my husband, Zach Weener Smith. We've recently wrote a book 33 00:02:05,720 --> 00:02:08,840 Speaker 1: called soon Ish Ten Emerging Technologies that will improve and 34 00:02:09,040 --> 00:02:11,840 Speaker 1: or ruin everything. It isn't you're stuck inside because it's 35 00:02:11,840 --> 00:02:14,640 Speaker 1: a pandemic. You should go read it. You should totally 36 00:02:14,639 --> 00:02:17,200 Speaker 1: read it. It's a wonderful book. It's super fun to read. 37 00:02:17,320 --> 00:02:20,440 Speaker 1: The comics are hilarious, and the science is super interesting 38 00:02:21,560 --> 00:02:24,960 Speaker 1: and it's very relevant. Actually. For today's episode of the podcast. 39 00:02:25,160 --> 00:02:27,400 Speaker 1: On this podcast, we'd like to talk about the physics 40 00:02:27,400 --> 00:02:29,800 Speaker 1: of the universe and what's the inside black holes and 41 00:02:29,960 --> 00:02:32,960 Speaker 1: how tiny particles work. But we also like to break 42 00:02:33,000 --> 00:02:37,720 Speaker 1: down the physics of everyday objects and future technology. Previously 43 00:02:37,760 --> 00:02:40,399 Speaker 1: on the podcast, we've talked about how solar panels work, 44 00:02:40,520 --> 00:02:44,640 Speaker 1: can fusion reactors be real? Wood space elevators actually work? 45 00:02:45,480 --> 00:02:47,440 Speaker 1: And the thing I think is super fun about that 46 00:02:47,720 --> 00:02:50,920 Speaker 1: is understanding sort of like what's on the forefront of science? 47 00:02:50,960 --> 00:02:54,160 Speaker 1: How are people actually solving these problems? You know, there's 48 00:02:54,160 --> 00:02:58,040 Speaker 1: a wonderful interplay between science fiction where like crazy ideas 49 00:02:58,080 --> 00:03:00,919 Speaker 1: about how the world might work are written into fiction 50 00:03:01,000 --> 00:03:04,240 Speaker 1: and then actual scientists making it happen. Does that happen 51 00:03:04,240 --> 00:03:09,639 Speaker 1: a lot in parasitology, Kelly, Oh jeez, we hope not 52 00:03:09,639 --> 00:03:11,840 Speaker 1: not yet. You know, if the what is the name 53 00:03:11,840 --> 00:03:15,040 Speaker 1: of the parasite in the expanse that takes over people's behavior? 54 00:03:15,320 --> 00:03:19,919 Speaker 1: The proto molecule, the proto molecule. Yeah, so hopefully James S. A. 55 00:03:20,040 --> 00:03:22,600 Speaker 1: Corey was totally wrong about that. I bet somebody out 56 00:03:22,600 --> 00:03:24,760 Speaker 1: there in their lab is thinking, I wonder if I 57 00:03:24,760 --> 00:03:27,760 Speaker 1: could actually build the protomolecule, and they're starting to write 58 00:03:27,760 --> 00:03:29,960 Speaker 1: grant proposals for that. I hope not. I hope that's 59 00:03:30,000 --> 00:03:34,840 Speaker 1: not fundable by the NSF. Well, today we are not 60 00:03:34,960 --> 00:03:37,920 Speaker 1: talking about the protomolecule or anything that we think will 61 00:03:38,040 --> 00:03:42,160 Speaker 1: lead to a more rapid demise of all of humanity. Instead, 62 00:03:42,320 --> 00:03:44,840 Speaker 1: we're going to tackle a really fun concept that comes 63 00:03:44,920 --> 00:03:47,600 Speaker 1: up a lot in fiction. We're asking the question today 64 00:03:47,640 --> 00:03:57,840 Speaker 1: on the podcast, could we build a cloak of invisibility? So? 65 00:03:57,920 --> 00:03:59,760 Speaker 1: Are you a fan of Lord of the Rings and 66 00:04:00,040 --> 00:04:02,800 Speaker 1: Ry Potter Kelly? Yes, I can't say I watched them regularly, 67 00:04:02,880 --> 00:04:04,760 Speaker 1: but yeah, I'm a fan. Yeah. So this kind of 68 00:04:04,760 --> 00:04:08,520 Speaker 1: stuff pops up all the time in fiction, this idea 69 00:04:08,680 --> 00:04:12,200 Speaker 1: of being invisible, of like sneaking around and having nobody 70 00:04:12,320 --> 00:04:15,320 Speaker 1: see you, being able to listen to people's conversations or 71 00:04:15,440 --> 00:04:18,919 Speaker 1: Rob Banks. Why do you think it's so fascinating? I mean, 72 00:04:18,960 --> 00:04:21,240 Speaker 1: I think we all love the idea of of knowing 73 00:04:21,279 --> 00:04:23,480 Speaker 1: what's going on when we're not in the room, and like, 74 00:04:23,520 --> 00:04:25,320 Speaker 1: as a naturalist, I would love to be able to 75 00:04:25,360 --> 00:04:28,359 Speaker 1: just sit in nature and watch stuff happening, because you know, 76 00:04:28,440 --> 00:04:30,680 Speaker 1: when you're there, you're you know, impacting what happens when 77 00:04:30,760 --> 00:04:32,280 Speaker 1: you know the deer are going to act differently if 78 00:04:32,279 --> 00:04:34,200 Speaker 1: you're there, and just being able to observe the world 79 00:04:34,240 --> 00:04:36,400 Speaker 1: as though you're not there. I think that's appealing in 80 00:04:36,440 --> 00:04:38,800 Speaker 1: a lot of ways. Well, that's actually like a real 81 00:04:38,880 --> 00:04:42,720 Speaker 1: science application for invisibility. I never even thought about that. 82 00:04:42,880 --> 00:04:45,400 Speaker 1: Ecologist would love it, college just would love it. I 83 00:04:45,400 --> 00:04:47,800 Speaker 1: would be terrified, though, to like sneak into a room 84 00:04:47,839 --> 00:04:50,200 Speaker 1: and hear people talking about me. I'm pretty sure I 85 00:04:50,240 --> 00:04:53,080 Speaker 1: don't want to hear what they have to say. I 86 00:04:53,120 --> 00:04:54,680 Speaker 1: don't think i'd want to hear it either. No, that's 87 00:04:54,720 --> 00:04:56,880 Speaker 1: why it appeals to me from a nature perspective. But 88 00:04:56,880 --> 00:04:59,600 Speaker 1: I'll leave the humans alone, I think. So. This kind 89 00:04:59,640 --> 00:05:02,320 Speaker 1: of stuff appears in Harry Potter and in Lord of 90 00:05:02,360 --> 00:05:05,600 Speaker 1: the Rings and in much much older writing. And it's 91 00:05:05,640 --> 00:05:08,080 Speaker 1: interesting to me how it first starts in sort of 92 00:05:08,120 --> 00:05:11,400 Speaker 1: like magic and fantasy based worlds, and then in like 93 00:05:11,440 --> 00:05:13,479 Speaker 1: the last hundred and fifty years, it appeared in like 94 00:05:13,600 --> 00:05:17,040 Speaker 1: science fiction stories as authors have tried to figure out, like, 95 00:05:17,120 --> 00:05:20,040 Speaker 1: what is the mechanism for this? How could this actually happen? 96 00:05:20,160 --> 00:05:23,479 Speaker 1: And it appeared first in an eighteen fifty story by 97 00:05:23,600 --> 00:05:26,200 Speaker 1: Fitz James O'Brien where there was a monster in a 98 00:05:26,279 --> 00:05:29,080 Speaker 1: house that was alive and you know, not a ghost 99 00:05:29,360 --> 00:05:32,760 Speaker 1: but invisible, so you couldn't see it. Was it cloaked? 100 00:05:32,760 --> 00:05:34,720 Speaker 1: It was it just straight up invisible? It was just 101 00:05:34,800 --> 00:05:37,839 Speaker 1: straight up invisible. Yeah, the whole monster itself was invisible. 102 00:05:37,880 --> 00:05:40,440 Speaker 1: And then maybe the most famous early appearance was of course, 103 00:05:40,680 --> 00:05:43,760 Speaker 1: in The Invisible Man by H. G. Wells, And this 104 00:05:43,880 --> 00:05:46,159 Speaker 1: was right around the turn of last century, and it 105 00:05:46,200 --> 00:05:48,840 Speaker 1: was just after X rays were discovered, and so people 106 00:05:48,839 --> 00:05:51,400 Speaker 1: were sort of like getting their minds around the concept 107 00:05:51,400 --> 00:05:53,560 Speaker 1: that there was different kinds of light and different kinds 108 00:05:53,560 --> 00:05:57,480 Speaker 1: of visibility, right, that our bodies are opaque to normal light, 109 00:05:57,520 --> 00:06:00,400 Speaker 1: but they could be transparent to other kinds of light. 110 00:06:00,480 --> 00:06:03,760 Speaker 1: That was like a mind blowing idea. That is pretty awesome. Yeah, 111 00:06:04,000 --> 00:06:06,679 Speaker 1: and so I think this god science fiction writers thinking 112 00:06:06,720 --> 00:06:09,800 Speaker 1: about what is visibility and what is invisibility? Then a 113 00:06:09,920 --> 00:06:13,080 Speaker 1: transition to science fictions. And now today maybe we'll talk 114 00:06:13,120 --> 00:06:17,520 Speaker 1: about how it could actually be science. And so today 115 00:06:17,520 --> 00:06:19,520 Speaker 1: on the podcast we will be answering that question and 116 00:06:19,560 --> 00:06:23,400 Speaker 1: digging into all the various ways that you could have invisibility. 117 00:06:23,520 --> 00:06:27,279 Speaker 1: The technology is underdeveloped, it's not actually there yet, but 118 00:06:27,360 --> 00:06:30,160 Speaker 1: you might be impressed by how far people have gotten. So, 119 00:06:30,279 --> 00:06:33,320 Speaker 1: as usual, I looked for volunteers for people who were 120 00:06:33,320 --> 00:06:36,719 Speaker 1: willing to speculate baselessly on how something worked or answer 121 00:06:36,800 --> 00:06:39,840 Speaker 1: a difficult physics question. So thank you to everyone who 122 00:06:39,920 --> 00:06:42,279 Speaker 1: was brave and lent your voice, And if you would 123 00:06:42,279 --> 00:06:45,440 Speaker 1: like to volunteer for future episodes, please write to us 124 00:06:45,440 --> 00:06:48,600 Speaker 1: two questions at Daniel and Jorge dot com. Here's what 125 00:06:48,640 --> 00:06:53,240 Speaker 1: people had to say. People have made really micro scale 126 00:06:53,520 --> 00:06:59,200 Speaker 1: invisibility cloaks. I think invisibility cliques can be built, and 127 00:06:59,279 --> 00:07:03,080 Speaker 1: I think at least one already does exist. I think 128 00:07:03,080 --> 00:07:06,960 Speaker 1: it works by making light bend around it. I'm not 129 00:07:07,000 --> 00:07:09,120 Speaker 1: sure if we can build a cloak per se, but 130 00:07:09,160 --> 00:07:13,280 Speaker 1: I know we can make invisibility happen by using fiber 131 00:07:13,360 --> 00:07:17,440 Speaker 1: optic cables. I think that's got to be a definite yes. 132 00:07:17,920 --> 00:07:19,760 Speaker 1: And I think it really depends on what you mean 133 00:07:19,840 --> 00:07:23,480 Speaker 1: by invisibility. But I think if if you consider a 134 00:07:23,720 --> 00:07:29,200 Speaker 1: chameleon to be invisible, then yeah, I've seen cases where 135 00:07:29,800 --> 00:07:37,800 Speaker 1: using cameras and displays and creatively arranged we can come close. Um. 136 00:07:37,840 --> 00:07:40,160 Speaker 1: I think it's an engineering problem more than a physics 137 00:07:40,240 --> 00:07:43,840 Speaker 1: problem at this point. Camouflage is something that has been 138 00:07:43,880 --> 00:07:46,600 Speaker 1: figured out in the animal kingdom. I mean, if you 139 00:07:46,640 --> 00:07:49,080 Speaker 1: look at an octopus then and a cuttle fish the 140 00:07:49,080 --> 00:07:53,360 Speaker 1: way that they can completely blend into their background. So 141 00:07:53,880 --> 00:07:59,200 Speaker 1: it seems like it's possible. Probably at some level. I 142 00:07:59,280 --> 00:08:03,080 Speaker 1: really don't think we can. The problem with the invisibility 143 00:08:03,080 --> 00:08:06,440 Speaker 1: clock is that if the wearer of the cloak is 144 00:08:06,520 --> 00:08:10,800 Speaker 1: invisible to anyone on the outside, then the wearer also 145 00:08:10,880 --> 00:08:15,480 Speaker 1: cannot see anything outside of the cloak. Probably not, i'd say, 146 00:08:17,240 --> 00:08:20,480 Speaker 1: mainly because I'm guessing anything that can bend light around 147 00:08:20,520 --> 00:08:24,400 Speaker 1: something with that force will probably have quite a horrendous 148 00:08:24,400 --> 00:08:28,360 Speaker 1: effect on anyone or anything that it is put around. No, 149 00:08:28,720 --> 00:08:31,640 Speaker 1: I don't think it's possible to build an invisibility cloak. 150 00:08:32,559 --> 00:08:37,920 Speaker 1: I would say not likely, just because you can build 151 00:08:37,960 --> 00:08:43,160 Speaker 1: it maybe invisible from one direction, but from multiple directions. UM, 152 00:08:43,400 --> 00:08:47,679 Speaker 1: I can't imagine it. I have heard of some invisibility 153 00:08:47,800 --> 00:08:53,720 Speaker 1: technology where it basically bends the light around something so 154 00:08:53,760 --> 00:08:57,840 Speaker 1: that it looks like you're seeing through it. UM. I 155 00:08:57,880 --> 00:09:02,120 Speaker 1: thought that it depended on the perspective of the viewer. 156 00:09:02,640 --> 00:09:05,080 Speaker 1: So what do you think of those answers, Kelly? I 157 00:09:05,120 --> 00:09:07,400 Speaker 1: thought they were really interesting answers. As a biologist, I 158 00:09:07,440 --> 00:09:09,840 Speaker 1: thought it was interesting that chameleons and cuttle fish came 159 00:09:09,880 --> 00:09:11,600 Speaker 1: up pretty often. And to be honest, when you told 160 00:09:11,600 --> 00:09:14,199 Speaker 1: me the topic of this, my first thought was, woh, well, 161 00:09:14,360 --> 00:09:17,080 Speaker 1: chameleons and octopuses can do it. I guess I sort 162 00:09:17,080 --> 00:09:19,280 Speaker 1: of matched up with some of these responses. What did 163 00:09:19,280 --> 00:09:22,319 Speaker 1: you think? Yeah? I was impressed. There's a huge variety 164 00:09:22,360 --> 00:09:24,920 Speaker 1: of possible ideas in here, and I love in these 165 00:09:24,920 --> 00:09:28,200 Speaker 1: responses hearing people sort of think on their feet. They 166 00:09:28,200 --> 00:09:30,800 Speaker 1: don't know the answer, they're thinking about it, they're wondering, 167 00:09:30,840 --> 00:09:33,760 Speaker 1: and that's like people doing physics right there, like taking 168 00:09:33,760 --> 00:09:35,880 Speaker 1: their understanding of the universe and trying to use it 169 00:09:35,920 --> 00:09:38,559 Speaker 1: to solve problems. Though. I love hearing people figure it 170 00:09:38,600 --> 00:09:41,360 Speaker 1: out and actually making some progress on the fly. I'm 171 00:09:41,400 --> 00:09:45,559 Speaker 1: impressed we have smart listeners totally alright. So let's dig 172 00:09:45,600 --> 00:09:47,640 Speaker 1: into it. And first, maybe the thing we should talk 173 00:09:47,679 --> 00:09:50,679 Speaker 1: about is what do we actually want to accomplish? If 174 00:09:50,720 --> 00:09:53,760 Speaker 1: we're like talking to DARPA about building an invisibility cloak, 175 00:09:53,840 --> 00:09:56,800 Speaker 1: what do we really mean buying visibility? What are the 176 00:09:56,880 --> 00:09:59,920 Speaker 1: specs that we want to achieve? So you talked about 177 00:10:00,120 --> 00:10:03,080 Speaker 1: invisibility in biology, and I'm super interested in that but 178 00:10:03,120 --> 00:10:04,600 Speaker 1: don't know a whole lot about it. Could you tell 179 00:10:04,679 --> 00:10:07,120 Speaker 1: us a little bit about how do octopy or chameleon 180 00:10:07,240 --> 00:10:11,320 Speaker 1: or cuddlefish achieve some sort of biological camouflage. Sure, so 181 00:10:11,360 --> 00:10:13,360 Speaker 1: I can't say that I'm an expert on this topic, 182 00:10:13,360 --> 00:10:16,680 Speaker 1: but my understanding is that they have these chromatophors, which 183 00:10:16,720 --> 00:10:19,839 Speaker 1: are cells that can expand and contract, and the cells 184 00:10:19,840 --> 00:10:23,520 Speaker 1: are always filled with pigments, and whether they're expanding or 185 00:10:23,600 --> 00:10:26,640 Speaker 1: contracted determines how much of the pigment you get to see. 186 00:10:27,200 --> 00:10:30,320 Speaker 1: And so by making more of this pigment visible, for example, 187 00:10:30,400 --> 00:10:33,880 Speaker 1: an octopus can become more brown by allowing more of 188 00:10:33,920 --> 00:10:37,520 Speaker 1: the brown pigment up to the surface. And really complicated 189 00:10:37,760 --> 00:10:42,280 Speaker 1: animals like chameleons might have different layers of these pigmented cells, 190 00:10:42,880 --> 00:10:45,360 Speaker 1: and by sort of turning on some layers and turning 191 00:10:45,360 --> 00:10:48,000 Speaker 1: off other layers, they can come up with really complicated 192 00:10:48,040 --> 00:10:51,960 Speaker 1: and complex color patterns. But usually what happens when they're 193 00:10:52,000 --> 00:10:55,520 Speaker 1: doing these things is they're staying like dead still. They're 194 00:10:55,520 --> 00:10:59,720 Speaker 1: not moving at all. And so I'm guessing that invisibility cloaks, 195 00:10:59,720 --> 00:11:02,120 Speaker 1: people who are wearing them expect to be able to 196 00:11:02,120 --> 00:11:04,080 Speaker 1: to move while they're wearing them. Is that true? What 197 00:11:04,120 --> 00:11:07,240 Speaker 1: do you think? I definitely think you want to be 198 00:11:07,280 --> 00:11:09,559 Speaker 1: able to sneak around. Yeah, I don't think you want 199 00:11:09,600 --> 00:11:12,160 Speaker 1: to just have to like squat somewhere and stay fixed. 200 00:11:12,200 --> 00:11:15,760 Speaker 1: But also does that really count as invisibility? In my mind, 201 00:11:15,800 --> 00:11:18,080 Speaker 1: what's happening is like an octopus is like sitting on 202 00:11:18,120 --> 00:11:20,880 Speaker 1: a coral, and then it makes itself look like a coral, 203 00:11:20,920 --> 00:11:23,880 Speaker 1: which is super amazing and impressive and not something I 204 00:11:23,920 --> 00:11:27,000 Speaker 1: could ever do. But it doesn't look like it's not there. 205 00:11:27,080 --> 00:11:30,600 Speaker 1: It just looks like it's more coral, right, yeah, fair enough, 206 00:11:30,600 --> 00:11:32,200 Speaker 1: which I think would be a cool trick for people 207 00:11:32,200 --> 00:11:34,280 Speaker 1: who want to sneak around, But I agree that it's 208 00:11:34,280 --> 00:11:36,760 Speaker 1: probably not the same thing as being invisible. Yeah, Like, 209 00:11:36,880 --> 00:11:38,600 Speaker 1: you know, you can make yourself look like a bush 210 00:11:38,679 --> 00:11:40,240 Speaker 1: or whatever, but if you want to walk into a 211 00:11:40,320 --> 00:11:42,640 Speaker 1: room and have nobody see that you're there, you can't 212 00:11:42,640 --> 00:11:45,520 Speaker 1: just like, oh, I'm gonna look like more chairs or something. 213 00:11:45,559 --> 00:11:47,760 Speaker 1: You need to blend in some way. So I think 214 00:11:47,800 --> 00:11:51,600 Speaker 1: that's awesome and impressive, but not technically invisibility, right yeah, 215 00:11:51,640 --> 00:11:53,920 Speaker 1: fair enough? All right, And then maybe we should disentangle 216 00:11:53,960 --> 00:11:58,200 Speaker 1: invisibility from another similar concept, which is stealth technology. A 217 00:11:58,280 --> 00:12:00,640 Speaker 1: lot of airplanes out there, you know, we have like 218 00:12:00,720 --> 00:12:03,760 Speaker 1: stealth airplanes that can't be seen by radar. That's a 219 00:12:03,840 --> 00:12:07,000 Speaker 1: really cool technology, but it's not also the same thing 220 00:12:07,200 --> 00:12:11,440 Speaker 1: as invisibility. It's more like being totally black or like 221 00:12:11,600 --> 00:12:15,400 Speaker 1: not reflecting anything. The way like a stealth airplane works 222 00:12:15,559 --> 00:12:17,679 Speaker 1: is that when you shoot radar at it, and radar 223 00:12:17,800 --> 00:12:20,440 Speaker 1: is just like another form of light, it doesn't bounce 224 00:12:20,480 --> 00:12:23,080 Speaker 1: anything back. Like a normal airplane, you can think of 225 00:12:23,120 --> 00:12:25,520 Speaker 1: like as a sphere, and if you bounce radar at it, 226 00:12:25,520 --> 00:12:28,079 Speaker 1: it's going to bounce some back at you. Has a reflection, 227 00:12:28,240 --> 00:12:30,800 Speaker 1: but a stealth airplane is like all these weird angles 228 00:12:30,840 --> 00:12:32,560 Speaker 1: and so it has the profile so that if you 229 00:12:32,600 --> 00:12:35,080 Speaker 1: shoot radar at it, the radar always bounces off in 230 00:12:35,120 --> 00:12:37,960 Speaker 1: another direction. It's all these like sharp edges. There's no 231 00:12:38,320 --> 00:12:41,200 Speaker 1: smooth curves that would always reflects something back at you. 232 00:12:41,360 --> 00:12:44,960 Speaker 1: And so that's also not invisibility, right, It doesn't reflect 233 00:12:45,000 --> 00:12:47,320 Speaker 1: any light. But it's sort of like equivalent to you know, 234 00:12:47,360 --> 00:12:51,800 Speaker 1: painting yourself black. That doesn't make people invisible, right, I mean, 235 00:12:51,800 --> 00:12:53,520 Speaker 1: it's it's pretty amazing that we figured out how to 236 00:12:53,520 --> 00:12:56,880 Speaker 1: do that, but yeah, I agree. Also not invisibility, Yeah, 237 00:12:56,960 --> 00:13:00,120 Speaker 1: not invisibility, like if you ordered an invisibility cloak that 238 00:13:00,200 --> 00:13:03,559 Speaker 1: just gave you like a black sheet, you'd be pretty disappointed. Yeah, yeah, 239 00:13:03,559 --> 00:13:07,520 Speaker 1: I want my money back for sure. All Right, So 240 00:13:07,760 --> 00:13:10,920 Speaker 1: we want something that's actually invisible, which means it looks 241 00:13:11,080 --> 00:13:13,320 Speaker 1: like you're not there, right. I want to be able 242 00:13:13,360 --> 00:13:16,240 Speaker 1: to see basically what's behind you. I want to get 243 00:13:16,280 --> 00:13:18,560 Speaker 1: an image in my eyes that would be the same 244 00:13:18,600 --> 00:13:22,040 Speaker 1: image as if you were not there. And this includes 245 00:13:22,080 --> 00:13:24,480 Speaker 1: being able to move or is it just not look 246 00:13:24,520 --> 00:13:26,719 Speaker 1: like you're there and you're just standing still? Like I 247 00:13:26,720 --> 00:13:29,360 Speaker 1: guess I'm wondering if moving is part of the definition here. Now, 248 00:13:29,400 --> 00:13:31,400 Speaker 1: I think moving is definitely part of the definition. I mean, 249 00:13:31,480 --> 00:13:34,240 Speaker 1: let's be aspirational, right, we're setting the bar high. We 250 00:13:34,240 --> 00:13:37,680 Speaker 1: want like, actual, real, useful invisibility, and so I think 251 00:13:37,840 --> 00:13:40,280 Speaker 1: we want to be able to move. And also I 252 00:13:40,320 --> 00:13:44,000 Speaker 1: think it's important that it works for different wavelengths of light. Right, 253 00:13:44,040 --> 00:13:46,280 Speaker 1: it can't just be like, oh, you're invisible in red 254 00:13:46,360 --> 00:13:49,360 Speaker 1: light or in green light, or in radio waves or 255 00:13:49,400 --> 00:13:52,840 Speaker 1: in microwaves. Has to work broadband across the whole spectrum, 256 00:13:53,040 --> 00:13:55,880 Speaker 1: otherwise you'd be pretty easy to detect. So more than 257 00:13:55,920 --> 00:13:58,200 Speaker 1: just what humans and their machines can view, is what 258 00:13:58,200 --> 00:14:01,400 Speaker 1: we're going for. Yeah, because other wrinkle, right, and that 259 00:14:01,480 --> 00:14:04,120 Speaker 1: maybe people don't really appreciate or think about, is that 260 00:14:04,240 --> 00:14:07,440 Speaker 1: humans are more than just visible. We actually glow like 261 00:14:07,520 --> 00:14:11,240 Speaker 1: we give off light. Because every object in the universe 262 00:14:11,280 --> 00:14:14,240 Speaker 1: that has a temperature is giving off infrared light. You're 263 00:14:14,440 --> 00:14:17,640 Speaker 1: radiating heat, which is why, for example, night vision goggles, 264 00:14:17,679 --> 00:14:20,000 Speaker 1: what they do is they see in the infrared, and 265 00:14:20,080 --> 00:14:22,440 Speaker 1: like every object in the universe that has a temperature, 266 00:14:22,480 --> 00:14:25,160 Speaker 1: you glow as some color. So the sun is super 267 00:14:25,240 --> 00:14:27,640 Speaker 1: duper hot, which is why it glows. In the visible light. 268 00:14:27,680 --> 00:14:29,600 Speaker 1: Where we take a piece of metal and heat it up, 269 00:14:29,640 --> 00:14:32,280 Speaker 1: it glows red or blue or white or whatever. Your 270 00:14:32,360 --> 00:14:35,760 Speaker 1: body is also glowing. So I think invisibility should mean 271 00:14:35,840 --> 00:14:37,720 Speaker 1: not just that you look like the thing behind you, 272 00:14:38,000 --> 00:14:40,160 Speaker 1: but that you don't give off any light also, so 273 00:14:40,200 --> 00:14:43,200 Speaker 1: it has to somehow block your heat. I had not 274 00:14:43,240 --> 00:14:46,840 Speaker 1: thought of that extra complication beforehand. That's really interesting. Yeah, 275 00:14:46,920 --> 00:14:49,920 Speaker 1: it's complicated. And in addition, I think if we're gonna 276 00:14:49,920 --> 00:14:52,080 Speaker 1: set the bar really high, it should be that you 277 00:14:52,120 --> 00:14:54,800 Speaker 1: can't tell any difference in the light that comes to you, 278 00:14:55,000 --> 00:14:57,760 Speaker 1: even like a time delay. Right, you can imagine, and 279 00:14:57,760 --> 00:15:00,000 Speaker 1: we're gonna dig into this and talk about various solutions 280 00:15:00,000 --> 00:15:02,520 Speaker 1: to invisibility. You don't want that the light that's coming 281 00:15:02,560 --> 00:15:06,040 Speaker 1: from behind you is slowed down as it passes through 282 00:15:06,120 --> 00:15:09,520 Speaker 1: you by your invisibility cloak, because then again, somebody could 283 00:15:09,560 --> 00:15:12,080 Speaker 1: detect that right and then if you started moving around 284 00:15:12,120 --> 00:15:14,560 Speaker 1: really fast, the image would be sort of flawed, sort 285 00:15:14,560 --> 00:15:18,400 Speaker 1: of like the Predators camouflage and fix seen those movies totally, 286 00:15:18,560 --> 00:15:20,640 Speaker 1: But I mean you can imagine if you're an early adopter, 287 00:15:20,760 --> 00:15:22,320 Speaker 1: you can like get away with some of these things 288 00:15:22,320 --> 00:15:26,880 Speaker 1: because people aren't expecting invisibility cloaks. But yes, as you 289 00:15:26,920 --> 00:15:28,680 Speaker 1: go further on, I think you've got to fix all 290 00:15:28,720 --> 00:15:32,720 Speaker 1: these problems first gen invisibility cloaks of lower standards. You know, 291 00:15:32,760 --> 00:15:34,560 Speaker 1: I was thinking about this last night. I was talking 292 00:15:34,600 --> 00:15:36,680 Speaker 1: to my thirteen year old about this, and he was thinking, 293 00:15:36,760 --> 00:15:40,440 Speaker 1: invisibility would that even really be a good idea, you know, 294 00:15:40,480 --> 00:15:42,920 Speaker 1: because could you even use it? He made this really 295 00:15:42,960 --> 00:15:45,800 Speaker 1: interesting point I hadn't thought of, which is, if you're invisible, 296 00:15:46,320 --> 00:15:49,160 Speaker 1: can you see the rest of the world. Because if 297 00:15:49,280 --> 00:15:51,880 Speaker 1: light is like passing through you and not interacting with you, 298 00:15:52,080 --> 00:15:54,640 Speaker 1: doesn't that mean that you're not seeing the rest of 299 00:15:54,680 --> 00:15:59,040 Speaker 1: the world. So if you're invisible, are you also then blind? Oh? Well, 300 00:15:59,040 --> 00:16:00,840 Speaker 1: that's an extra complicate ation. I mean, could there be 301 00:16:00,880 --> 00:16:02,960 Speaker 1: like a little screen inside of your cloak that's showing 302 00:16:03,000 --> 00:16:05,960 Speaker 1: you what's going on outside? Yeah, you need something like that, right, 303 00:16:05,960 --> 00:16:08,480 Speaker 1: otherwise you'd be totally blind. And then I thought, hold 304 00:16:08,480 --> 00:16:10,800 Speaker 1: on a second, even if you aren't blind, even if 305 00:16:11,080 --> 00:16:14,120 Speaker 1: the world can't see you, but you can still see outside, 306 00:16:14,360 --> 00:16:17,200 Speaker 1: you're probably not seeing yourself, right. You can't see your 307 00:16:17,360 --> 00:16:20,600 Speaker 1: arms or your hands or anything. And I started thinking about, like, 308 00:16:20,640 --> 00:16:23,000 Speaker 1: what is it like to walk up a flight of 309 00:16:23,080 --> 00:16:26,200 Speaker 1: stairs if you can't see your own body? I mean, 310 00:16:26,400 --> 00:16:29,000 Speaker 1: you're the biologists tell me, like, doesn't our brain rely 311 00:16:29,160 --> 00:16:31,360 Speaker 1: on seeing where your feet are to be able to 312 00:16:31,400 --> 00:16:33,320 Speaker 1: go upstairs? Like I can't walk up a flight of 313 00:16:33,360 --> 00:16:36,000 Speaker 1: stairs with my eyes closed? Very well? Totally? Yeah, No, 314 00:16:36,040 --> 00:16:38,080 Speaker 1: that's that's a great point. You. I guess you definitely 315 00:16:38,080 --> 00:16:39,840 Speaker 1: need to do a lot of practice. So you know, 316 00:16:39,960 --> 00:16:41,840 Speaker 1: like I think astronauts when they go into space, they 317 00:16:41,880 --> 00:16:43,880 Speaker 1: sort of learned to live without some of the cues 318 00:16:43,920 --> 00:16:46,200 Speaker 1: that they're used to on Earth. So I guess with 319 00:16:46,320 --> 00:16:49,400 Speaker 1: enough practice, you could learn to stop relying on being 320 00:16:49,440 --> 00:16:51,760 Speaker 1: able to see what your body is doing to accomplish 321 00:16:51,760 --> 00:16:54,280 Speaker 1: that task. But I definitely think you'd be clumsy initially. 322 00:16:54,360 --> 00:16:57,840 Speaker 1: You'd need some training in this cloak. You definitely would. 323 00:16:57,880 --> 00:17:00,720 Speaker 1: So the first end click probably not super sophisticated, and 324 00:17:00,760 --> 00:17:04,240 Speaker 1: the first and gen user probably pretty clumsy. I mean 325 00:17:04,240 --> 00:17:06,959 Speaker 1: you'd be like banging around into stuff. And also like 326 00:17:07,040 --> 00:17:09,280 Speaker 1: how would you walk through a crowd of people? Right, 327 00:17:09,320 --> 00:17:11,960 Speaker 1: Nobody would see you, so they wouldn't know to avoid you, 328 00:17:12,080 --> 00:17:14,399 Speaker 1: so they'd be like bumping into you all the time. 329 00:17:14,920 --> 00:17:17,119 Speaker 1: The more I think about it, the more like complicated 330 00:17:17,200 --> 00:17:20,359 Speaker 1: it would be to be invisible. Yeah, there might just 331 00:17:20,400 --> 00:17:22,639 Speaker 1: be very specific situations where you can use it, and 332 00:17:22,720 --> 00:17:24,960 Speaker 1: otherwise you're likely to get found out. Yeah, Like you 333 00:17:25,000 --> 00:17:27,159 Speaker 1: can't stand in the rain if you're invisible. Right, we 334 00:17:27,160 --> 00:17:31,879 Speaker 1: don't have invisibility cloth. That's gonna be like rain permeable. Also, anyway, 335 00:17:31,920 --> 00:17:33,960 Speaker 1: it sounds really complicated. You need to carry a huge 336 00:17:33,960 --> 00:17:39,480 Speaker 1: battery pack or a really long extension cord also invisible, 337 00:17:40,320 --> 00:17:42,159 Speaker 1: which no one can trip over, so you need to 338 00:17:42,160 --> 00:17:45,840 Speaker 1: make sure your path doesn't cross anyone else's all right, 339 00:17:45,880 --> 00:17:48,080 Speaker 1: So I want to learn more about the technologies that 340 00:17:48,119 --> 00:17:50,920 Speaker 1: have been developed so far. But first let's take a break, 341 00:18:04,200 --> 00:18:06,679 Speaker 1: and we're back and we're talking about whether or not 342 00:18:06,760 --> 00:18:10,840 Speaker 1: you could actually make an invisibility cloak Daniel, What do 343 00:18:10,880 --> 00:18:13,000 Speaker 1: we know about how you can make invisibility cloaks? Has 344 00:18:13,040 --> 00:18:15,760 Speaker 1: anyone done research on this? People have been doing this 345 00:18:15,840 --> 00:18:18,360 Speaker 1: for a while, actually, and this is a really fascinating 346 00:18:18,440 --> 00:18:22,000 Speaker 1: field where people had ideas like fifty years ago and 347 00:18:22,040 --> 00:18:24,280 Speaker 1: then it's sort of lay dormant for a long time, 348 00:18:24,320 --> 00:18:26,640 Speaker 1: nobody was doing anything. I think people sort of shrugged 349 00:18:26,640 --> 00:18:29,879 Speaker 1: it off as basically impossible, like the flash technology. And 350 00:18:29,920 --> 00:18:32,400 Speaker 1: then about fifteen years ago there was like a little 351 00:18:32,400 --> 00:18:35,760 Speaker 1: renaissance where people had sort of like starting ideas for 352 00:18:35,840 --> 00:18:37,960 Speaker 1: how you could actually tackle this and tried it and 353 00:18:38,000 --> 00:18:41,200 Speaker 1: made some progress and now it's like a flourishing field again. 354 00:18:41,359 --> 00:18:44,760 Speaker 1: So it's an exciting time actually to talk about invisibility. 355 00:18:44,800 --> 00:18:46,960 Speaker 1: Was there anything fifteen years ago that kicked it off, 356 00:18:46,960 --> 00:18:49,159 Speaker 1: like some technology that made people think it might be 357 00:18:49,200 --> 00:18:52,160 Speaker 1: feasible or was it just sort of random, probably some 358 00:18:52,240 --> 00:18:55,480 Speaker 1: scientists staying up late reading some science fiction novel and 359 00:18:55,520 --> 00:18:58,280 Speaker 1: then just having an idea. You know, it's cool the 360 00:18:58,280 --> 00:19:00,760 Speaker 1: way these things happen, that there's like progress and then 361 00:19:00,800 --> 00:19:03,000 Speaker 1: it's abandoned for thirty years, and then somebody has an 362 00:19:03,040 --> 00:19:05,159 Speaker 1: idea and then it moves forward anyway. That's sort of 363 00:19:05,200 --> 00:19:08,919 Speaker 1: like three different ways you might achieve invisibility. There's like 364 00:19:09,200 --> 00:19:13,040 Speaker 1: projecting your image on something, there's like recreating your image 365 00:19:13,040 --> 00:19:15,239 Speaker 1: like adaptive camouflage, and then when I think is the 366 00:19:15,280 --> 00:19:18,879 Speaker 1: most promising of like bending an image around you. But 367 00:19:19,119 --> 00:19:21,160 Speaker 1: let's talk about them in turn. So the first idea 368 00:19:21,200 --> 00:19:24,159 Speaker 1: of this idea of image projection is pretty hokey, but 369 00:19:24,160 --> 00:19:26,399 Speaker 1: I got a lot of attention In like two thousand 370 00:19:26,400 --> 00:19:28,160 Speaker 1: and three, you win a lab in Tokyo put out 371 00:19:28,160 --> 00:19:30,240 Speaker 1: a video showing how it would work, and the idea 372 00:19:30,320 --> 00:19:33,880 Speaker 1: here it's basically, you have a camera behind you that's 373 00:19:33,920 --> 00:19:36,040 Speaker 1: taking an image of what's going on behind you, and 374 00:19:36,040 --> 00:19:38,720 Speaker 1: then you have a projector in front of you that's 375 00:19:38,760 --> 00:19:42,760 Speaker 1: like shining that image onto your invisibility cloak. So then 376 00:19:42,880 --> 00:19:47,000 Speaker 1: somebody standing basically next to the projector is technically seeing 377 00:19:47,160 --> 00:19:49,760 Speaker 1: through you because they're seeing an image of what's behind 378 00:19:49,800 --> 00:19:53,800 Speaker 1: you projected onto this cloak you're wearing. How smooth is 379 00:19:53,840 --> 00:19:55,919 Speaker 1: the image, Like if there's any wrinkle in the cloak? 380 00:19:56,080 --> 00:19:57,600 Speaker 1: Is there a wrinkle in the image, do you need 381 00:19:57,680 --> 00:20:00,560 Speaker 1: to like stand there like a scarecrow. Yeah, you basically 382 00:20:00,560 --> 00:20:03,080 Speaker 1: need to stand there like a scarecrow because you're right, 383 00:20:03,119 --> 00:20:05,920 Speaker 1: like you're projecting this and so the image doesn't lie 384 00:20:06,040 --> 00:20:09,440 Speaker 1: smoothly on the cloak, right, but it sort of works. 385 00:20:09,480 --> 00:20:12,480 Speaker 1: If you stand there and hold your cloak pretty flat, 386 00:20:12,520 --> 00:20:15,080 Speaker 1: then you basically look like a movie screen and it's 387 00:20:15,119 --> 00:20:17,840 Speaker 1: sort of cool. It gives this sense of invisibility. You 388 00:20:17,840 --> 00:20:20,280 Speaker 1: could definitely tell like, oh, where's the edge of the cloak, 389 00:20:20,440 --> 00:20:22,400 Speaker 1: and you can see the guy's face because your face 390 00:20:22,440 --> 00:20:24,360 Speaker 1: doesn't make a very good screen. But if you look 391 00:20:24,400 --> 00:20:28,320 Speaker 1: at this video from this Tokyo experiment, it's invisibility ish, 392 00:20:28,560 --> 00:20:30,600 Speaker 1: you know. It gives you that like the flavor of it. 393 00:20:30,800 --> 00:20:32,680 Speaker 1: So you might be able to like stand still as 394 00:20:32,680 --> 00:20:35,439 Speaker 1: somebody passes by and maybe they won't see you if 395 00:20:35,440 --> 00:20:38,320 Speaker 1: they're not looking too hard. Yeah. Maybe. And also they 396 00:20:38,359 --> 00:20:40,480 Speaker 1: have to like not pay attention to the fact that 397 00:20:40,520 --> 00:20:44,000 Speaker 1: there's a projector they're showing this image onto you, and 398 00:20:44,040 --> 00:20:45,719 Speaker 1: they have to be an exactly the right angle for 399 00:20:45,760 --> 00:20:47,800 Speaker 1: this to work. So it's sort of like a cool 400 00:20:47,960 --> 00:20:50,800 Speaker 1: demonstration that like maybe you could use to film a 401 00:20:50,880 --> 00:20:53,840 Speaker 1: movie about invisibility to make that special effect, But it's 402 00:20:53,840 --> 00:20:56,080 Speaker 1: never going to be like what we talked about, an 403 00:20:56,119 --> 00:20:58,760 Speaker 1: actual invisibility cloak. You could us to walk around and 404 00:20:58,800 --> 00:21:00,520 Speaker 1: do stuff. Yeah, right, if fails a lot of the 405 00:21:00,560 --> 00:21:02,879 Speaker 1: criteria we were talking about. Yeah, but it's sort of 406 00:21:02,880 --> 00:21:05,200 Speaker 1: like got people excited, and you know, there are some 407 00:21:05,320 --> 00:21:08,200 Speaker 1: actual applications of it, Like it could be useful in 408 00:21:08,240 --> 00:21:10,119 Speaker 1: some ways now when you want to sneak around in 409 00:21:10,119 --> 00:21:12,399 Speaker 1: the faculty meeting and here where people really think about 410 00:21:12,400 --> 00:21:14,919 Speaker 1: your work. But you know, you could imagine using in 411 00:21:14,960 --> 00:21:18,159 Speaker 1: some scenarios, Like people have talked about using it for airplanes, 412 00:21:18,200 --> 00:21:21,240 Speaker 1: Like if you can make the floor of the cockpit 413 00:21:21,520 --> 00:21:24,560 Speaker 1: basically invisible, then a pilot would have like a better 414 00:21:24,600 --> 00:21:26,359 Speaker 1: sense for where they are. It might be easier to 415 00:21:26,440 --> 00:21:29,280 Speaker 1: fly if you like projected an image of the ground 416 00:21:29,760 --> 00:21:32,679 Speaker 1: onto the floor of the cockpit, sort of a similar application. 417 00:21:32,920 --> 00:21:36,480 Speaker 1: Do pilots have a lot of problems with that? I 418 00:21:36,520 --> 00:21:38,680 Speaker 1: don't think pilots too much to the landing anymore. I 419 00:21:38,680 --> 00:21:41,200 Speaker 1: think it's mostly AI these days, and AI doesn't care 420 00:21:41,240 --> 00:21:44,520 Speaker 1: at all these images. But maybe it'd be cool, like 421 00:21:44,640 --> 00:21:47,800 Speaker 1: for passengers, you know, if like the floor the airplane 422 00:21:48,040 --> 00:21:50,159 Speaker 1: looked like it wasn't there, but they think i'd be 423 00:21:50,160 --> 00:21:52,879 Speaker 1: cool with that would be like terrifying. I think it 424 00:21:52,960 --> 00:21:56,359 Speaker 1: might be terrifying. It might depend on the person or 425 00:21:56,440 --> 00:21:58,080 Speaker 1: the person you're sitting next to you. I think i'd 426 00:21:58,119 --> 00:21:59,560 Speaker 1: be cool with it, but if the person next to 427 00:21:59,560 --> 00:22:02,600 Speaker 1: me started to get nervous, that would make me nervous. Well. 428 00:22:02,640 --> 00:22:05,199 Speaker 1: I remember Odd airplanes when they first had this feature 429 00:22:05,400 --> 00:22:07,040 Speaker 1: that they had a bunch of cameras and you could 430 00:22:07,040 --> 00:22:09,639 Speaker 1: do yourself like cycle through them and like look down 431 00:22:09,800 --> 00:22:12,360 Speaker 1: or back or outside. I thought that was super cool, 432 00:22:12,600 --> 00:22:15,119 Speaker 1: like connect to you with what's going on outside the airplane, 433 00:22:15,160 --> 00:22:17,520 Speaker 1: because otherwise you feel like you're in this bubble. You 434 00:22:17,560 --> 00:22:19,159 Speaker 1: get on it in l A, you get off it 435 00:22:19,200 --> 00:22:22,880 Speaker 1: in New York. You don't really see experience the transition much. 436 00:22:22,920 --> 00:22:24,960 Speaker 1: So I think it's cool to be connected to what's 437 00:22:24,960 --> 00:22:27,680 Speaker 1: going on outside. But I think that would be pretty terrifying. 438 00:22:27,840 --> 00:22:29,920 Speaker 1: When was that a thing that does sound awesome? Yeah, 439 00:22:30,040 --> 00:22:31,920 Speaker 1: I think it's you know, in the last ten or 440 00:22:32,000 --> 00:22:33,959 Speaker 1: fifteen years or so, when they you had like your 441 00:22:34,000 --> 00:22:36,719 Speaker 1: own little screen that you could control yourself rather than 442 00:22:36,760 --> 00:22:39,280 Speaker 1: like everybody watching the same movie, and so you could 443 00:22:39,359 --> 00:22:41,040 Speaker 1: look at these cameras. It's like a camera in the 444 00:22:41,080 --> 00:22:43,119 Speaker 1: nose and a camera in the tail. I thought that 445 00:22:43,160 --> 00:22:45,440 Speaker 1: was pretty cool. I guess I've been flying the cheap airlines. 446 00:22:45,480 --> 00:22:48,280 Speaker 1: I gotta I gotta upgrade. That does sound fun. You 447 00:22:48,280 --> 00:22:51,400 Speaker 1: gotta get some of that government funding. There are other applications, 448 00:22:51,400 --> 00:22:54,240 Speaker 1: like you could imagine painting the inside of your car 449 00:22:54,760 --> 00:22:56,880 Speaker 1: with a view of what's going on outside, like, hey, 450 00:22:56,920 --> 00:22:59,520 Speaker 1: maybe no more blind spots, right, Or you could look 451 00:22:59,520 --> 00:23:01,840 Speaker 1: out of your car and actually see what's behind you. 452 00:23:01,920 --> 00:23:03,920 Speaker 1: We have sort of a version of this already where 453 00:23:03,920 --> 00:23:06,919 Speaker 1: people have like cameras on their license plates and you 454 00:23:06,920 --> 00:23:08,320 Speaker 1: can just look at a screen in front of you 455 00:23:08,359 --> 00:23:10,240 Speaker 1: and see what's behind you. But it would be sort 456 00:23:10,240 --> 00:23:13,399 Speaker 1: of cool if the car didn't block your view at all. Yeah, 457 00:23:13,480 --> 00:23:15,840 Speaker 1: that would be awesome. I bet that would save some lives. Yeah, 458 00:23:15,960 --> 00:23:20,160 Speaker 1: And I read about some applications where in surgery, for example, 459 00:23:20,320 --> 00:23:22,960 Speaker 1: you could paint an image of what's behind the surgeon's 460 00:23:23,040 --> 00:23:25,280 Speaker 1: hand on his hand so he can hear she could 461 00:23:25,359 --> 00:23:28,040 Speaker 1: see what they were doing better, like make their own 462 00:23:28,080 --> 00:23:30,520 Speaker 1: hands invisible. So that would be I mean, if you 463 00:23:30,640 --> 00:23:32,359 Speaker 1: got your hand inside a body, there's gotta be a 464 00:23:32,400 --> 00:23:34,320 Speaker 1: lot of things getting in the way of the projection 465 00:23:34,400 --> 00:23:36,679 Speaker 1: getting to the hands. So would it be like the 466 00:23:36,720 --> 00:23:40,600 Speaker 1: gloves projecting, like would you have fancy gloves? Yeah, I 467 00:23:40,640 --> 00:23:43,080 Speaker 1: guess if the body is opened, then you'd want, just 468 00:23:43,119 --> 00:23:46,040 Speaker 1: like the gloves to have a projection on them. But 469 00:23:46,160 --> 00:23:49,040 Speaker 1: if it's closed and you're doing it like laparoscopically, maybe 470 00:23:49,040 --> 00:23:51,199 Speaker 1: you could like project an image of what's going on 471 00:23:51,280 --> 00:23:53,800 Speaker 1: inside the body, like on the torso that would be 472 00:23:53,840 --> 00:23:55,400 Speaker 1: kind of cool. So it would like look like you're 473 00:23:55,440 --> 00:23:57,840 Speaker 1: opened up, even if you're not. That would be super cool. 474 00:23:58,280 --> 00:24:01,439 Speaker 1: That does sound super cool, you know, that's fun. That's interesting, 475 00:24:01,440 --> 00:24:04,280 Speaker 1: But it's definitely not real invisibility, right, and it's not 476 00:24:04,320 --> 00:24:06,720 Speaker 1: a cloak, and it's not a cloak, right. And so 477 00:24:07,040 --> 00:24:09,280 Speaker 1: moving on from that is a second category, which I 478 00:24:09,280 --> 00:24:11,879 Speaker 1: think is closer to what we're trying to do, and 479 00:24:11,920 --> 00:24:15,399 Speaker 1: this is like image recreation. So it's the same idea 480 00:24:15,440 --> 00:24:17,720 Speaker 1: where you're like gathering the image on one side and 481 00:24:17,760 --> 00:24:19,960 Speaker 1: creating it on the other side, but instead of using 482 00:24:19,960 --> 00:24:22,479 Speaker 1: like a projector has to be like far away from 483 00:24:22,560 --> 00:24:24,439 Speaker 1: you and then the image only works at one angle, 484 00:24:24,840 --> 00:24:28,560 Speaker 1: you have basically like adaptive camouflage. Imagine like the cloak 485 00:24:28,640 --> 00:24:31,480 Speaker 1: being made out of pixels. And it has cameras all 486 00:24:31,520 --> 00:24:34,840 Speaker 1: over the place and pixels, and so it's taking pictures 487 00:24:34,880 --> 00:24:38,399 Speaker 1: of what's behind you and creating that image on the 488 00:24:38,400 --> 00:24:41,280 Speaker 1: pixels on the outside of the cloak. Well, and so 489 00:24:41,320 --> 00:24:43,280 Speaker 1: you still have the problem with needing to make sure 490 00:24:43,280 --> 00:24:46,720 Speaker 1: you're not bending or folding anywhere, right, Yeah, maybe, I 491 00:24:46,760 --> 00:24:50,520 Speaker 1: mean it's potentially with like fancy computation and AI, you 492 00:24:50,520 --> 00:24:53,520 Speaker 1: could imagine that the cloak would sort of know how 493 00:24:53,560 --> 00:24:56,679 Speaker 1: it's arranged, and so it could know like where the 494 00:24:56,720 --> 00:25:00,199 Speaker 1: cameras are pointed and how the cloak is folded to 495 00:25:00,280 --> 00:25:03,000 Speaker 1: create the image in just the right way. A simpler version, 496 00:25:03,000 --> 00:25:05,879 Speaker 1: which is like painting image on the cloak, assuming it's flat, 497 00:25:05,960 --> 00:25:08,160 Speaker 1: but that might not always work. But if you knew 498 00:25:08,200 --> 00:25:10,160 Speaker 1: how it was curved, you might be able to adjust 499 00:25:10,200 --> 00:25:12,400 Speaker 1: how you're painting the image to still make it work. 500 00:25:12,600 --> 00:25:15,119 Speaker 1: So that is totally epic, and it sounds like it 501 00:25:15,119 --> 00:25:18,639 Speaker 1: would require a lot of computing ability, So like to 502 00:25:18,920 --> 00:25:21,200 Speaker 1: do this, do you need to have like a big 503 00:25:21,240 --> 00:25:24,119 Speaker 1: battery or carrying a computer inside the cloak with you. 504 00:25:25,359 --> 00:25:27,600 Speaker 1: I'm gonna imagine you're carrying like one of those old 505 00:25:27,640 --> 00:25:30,480 Speaker 1: tower computers from like the year two thousand inside and 506 00:25:30,480 --> 00:25:33,240 Speaker 1: people are like, I hear the fan worrying on your computer, man, 507 00:25:33,400 --> 00:25:38,640 Speaker 1: Like that would give you away. Yeah, you need sound 508 00:25:38,680 --> 00:25:41,000 Speaker 1: canceling something. Yeah. But you know, in terms of like 509 00:25:41,040 --> 00:25:45,040 Speaker 1: the general possibility, you could imagine maybe solar power and 510 00:25:45,240 --> 00:25:49,680 Speaker 1: super micro computers of the future could potentially pull this off. 511 00:25:49,760 --> 00:25:52,280 Speaker 1: And I think this is the basis of the Predators 512 00:25:52,320 --> 00:25:56,080 Speaker 1: invisibility in this sort of like adaptive camouflage that projected 513 00:25:56,119 --> 00:25:59,119 Speaker 1: the image behind him. It created the image on his 514 00:25:59,200 --> 00:26:01,160 Speaker 1: surface so that you could see it. And I think 515 00:26:01,200 --> 00:26:02,919 Speaker 1: one cool thing about that is that I think it 516 00:26:03,119 --> 00:26:06,960 Speaker 1: should work from any angle. Right. It shouldn't matter necessarily 517 00:26:07,200 --> 00:26:10,399 Speaker 1: what direction you're looking at the cloak from. It should 518 00:26:10,400 --> 00:26:12,520 Speaker 1: still be able to work as long as you create 519 00:26:12,560 --> 00:26:15,000 Speaker 1: the right image. You've got from all sides you need 520 00:26:15,080 --> 00:26:17,840 Speaker 1: cameras looking out, and then from all sides you need 521 00:26:17,880 --> 00:26:21,320 Speaker 1: pixels so that if somebody walks behind you, you're still invisible. 522 00:26:21,359 --> 00:26:24,280 Speaker 1: So is that the idea. That's the idea. Yeah, And 523 00:26:24,440 --> 00:26:26,960 Speaker 1: people are actually working on this, and there's a lab 524 00:26:27,280 --> 00:26:29,680 Speaker 1: I've seen one of their papers where they have these 525 00:26:29,880 --> 00:26:34,359 Speaker 1: thermo chromic liquid crystals. Liquid crystals are these things that 526 00:26:34,400 --> 00:26:36,000 Speaker 1: are very cool. A lot of people have l c 527 00:26:36,160 --> 00:26:39,200 Speaker 1: D displays on their computers or on their calculators or whatever. 528 00:26:39,240 --> 00:26:40,840 Speaker 1: But these can be flexible, so they can be like 529 00:26:40,960 --> 00:26:44,119 Speaker 1: woven into fabric and they can respond, of course, you know, 530 00:26:44,200 --> 00:26:47,159 Speaker 1: to computation, and so you can create basically any image. 531 00:26:47,280 --> 00:26:50,080 Speaker 1: And these are thermo chromic, which means that they change 532 00:26:50,119 --> 00:26:53,280 Speaker 1: their color based on the temperature. Remember those mugs that 533 00:26:53,320 --> 00:26:55,920 Speaker 1: if you poured hot water into them, an image appeared 534 00:26:56,000 --> 00:26:58,400 Speaker 1: or disappeared or something. I have one that says best 535 00:26:58,440 --> 00:27:01,320 Speaker 1: daughter in law. Wait, and what happens when you pour 536 00:27:01,320 --> 00:27:03,560 Speaker 1: water into it changes to worse daughter in law or something. 537 00:27:04,560 --> 00:27:06,760 Speaker 1: You know it's black, and then it says best daughter 538 00:27:06,760 --> 00:27:08,920 Speaker 1: in law. But yeah, maybe there's a secret message in there. 539 00:27:09,920 --> 00:27:12,200 Speaker 1: If you pour hot enough water in there, you see 540 00:27:12,240 --> 00:27:17,800 Speaker 1: the secret message. I know how they really feel. Then yeah, no, 541 00:27:17,880 --> 00:27:19,520 Speaker 1: I don't want to get you in trouble with your family. 542 00:27:20,040 --> 00:27:21,840 Speaker 1: So I've seen an example of this. They have a 543 00:27:21,920 --> 00:27:24,919 Speaker 1: small patch like a few inches by a few inches 544 00:27:25,200 --> 00:27:29,200 Speaker 1: that can effectively create an image of what's behind the user. 545 00:27:29,280 --> 00:27:31,600 Speaker 1: But you're already takes a lot of computation, and if 546 00:27:31,600 --> 00:27:33,080 Speaker 1: you want it to be very effective, it has to 547 00:27:33,119 --> 00:27:36,159 Speaker 1: work quickly, right, has to like really quickly update the image, 548 00:27:36,160 --> 00:27:38,560 Speaker 1: otherwise it will be obvious if you move or somebody 549 00:27:38,800 --> 00:27:41,600 Speaker 1: changes their perspective. So if this depends on temperature, if 550 00:27:41,600 --> 00:27:45,199 Speaker 1: somebody had like a temperature sensing device, would they be 551 00:27:45,280 --> 00:27:48,200 Speaker 1: able to detect your cloak? No, because the cool thing 552 00:27:48,280 --> 00:27:51,640 Speaker 1: is that this thing can also cloak your temperature. These 553 00:27:51,640 --> 00:27:54,480 Speaker 1: pixels can create an arbitrary color, but they can also 554 00:27:54,840 --> 00:27:58,280 Speaker 1: heat up or cool down to cloak your temperature. For example, 555 00:27:58,440 --> 00:28:00,840 Speaker 1: if you're in a warm environment, you want to give 556 00:28:00,880 --> 00:28:03,200 Speaker 1: off a lot of heat. If you're in a cold environment, 557 00:28:03,240 --> 00:28:04,760 Speaker 1: you want to not give off a lot of heat. 558 00:28:04,880 --> 00:28:07,200 Speaker 1: So that's actually a really cool application of this sort 559 00:28:07,240 --> 00:28:10,400 Speaker 1: of like adaptive camouflage that it can cloak you not 560 00:28:10,600 --> 00:28:13,240 Speaker 1: just in terms of visible light, but also in terms 561 00:28:13,320 --> 00:28:17,240 Speaker 1: of infrared light, effectively your temperature. What is the largest 562 00:28:17,520 --> 00:28:19,520 Speaker 1: size of one of these that they've been able to make. 563 00:28:19,520 --> 00:28:21,960 Speaker 1: Are we talking about cloaks? Are we talking about, you know, 564 00:28:22,040 --> 00:28:24,120 Speaker 1: postage stamps where this has been tried out so far. 565 00:28:24,760 --> 00:28:27,600 Speaker 1: We're talking about like basically a napkin. So it's an 566 00:28:27,600 --> 00:28:30,359 Speaker 1: invisibility napkin, so you might be able to like hide 567 00:28:30,359 --> 00:28:32,400 Speaker 1: a small road in behind it, you know, but you're 568 00:28:32,400 --> 00:28:34,920 Speaker 1: definitely not squeezing behind this napkin. But you know it's 569 00:28:34,920 --> 00:28:38,480 Speaker 1: also chunky, Like the pixels are not very small, they're 570 00:28:38,480 --> 00:28:40,400 Speaker 1: like a centimeter and by a centimeter. But you know, 571 00:28:40,480 --> 00:28:43,959 Speaker 1: these are engineering problems, and so as I often like 572 00:28:44,040 --> 00:28:46,080 Speaker 1: to say, you know, the physics has been figured out, 573 00:28:46,120 --> 00:28:48,160 Speaker 1: the idea is there, and we just hand it off 574 00:28:48,200 --> 00:28:50,360 Speaker 1: to the engineers and they can make the pixels smaller 575 00:28:50,400 --> 00:28:52,680 Speaker 1: and make it the battery more efficient, and make the 576 00:28:52,720 --> 00:28:54,800 Speaker 1: cameras better and you know, it's a it's a tech 577 00:28:54,840 --> 00:28:59,040 Speaker 1: problem now exactly. There'll be an app for it eventually, 578 00:28:59,160 --> 00:29:01,840 Speaker 1: no doubt. So that's image projection, which I think is 579 00:29:01,840 --> 00:29:05,400 Speaker 1: pretty hokey, and then like image recreation or adaptive camouflage, 580 00:29:05,440 --> 00:29:08,360 Speaker 1: which I think has some promise, but also there's definitely 581 00:29:08,400 --> 00:29:10,760 Speaker 1: some issues. They're like the one that you identified, all 582 00:29:10,840 --> 00:29:13,680 Speaker 1: this computation that's happening inside the cloak that would get 583 00:29:13,720 --> 00:29:16,360 Speaker 1: pretty warm. I'm joking around, but that's not a small 584 00:29:16,400 --> 00:29:19,920 Speaker 1: tech problem to solve. This seems like a good place 585 00:29:19,960 --> 00:29:37,080 Speaker 1: to stop, So let's take a quick break and we're back. Okay, So, Daniel, 586 00:29:37,080 --> 00:29:39,520 Speaker 1: you said that there were three different sort of types 587 00:29:39,560 --> 00:29:43,600 Speaker 1: of technologies for invisibility cloaks. Let's tackle the third, all right, 588 00:29:43,680 --> 00:29:45,840 Speaker 1: and this is I think the one that might actually 589 00:29:45,840 --> 00:29:49,480 Speaker 1: one day achieve like actual invisibility and real cloaking, so 590 00:29:49,800 --> 00:29:54,160 Speaker 1: I'm pretty excited about it more. The idea here is 591 00:29:54,160 --> 00:29:57,959 Speaker 1: basically image bending. Instead of projecting the image onto you 592 00:29:58,360 --> 00:30:02,360 Speaker 1: or recreating the image, interrupting it, digesting and computing and 593 00:30:02,360 --> 00:30:04,760 Speaker 1: recreating it, it's like, just take the light that was 594 00:30:04,800 --> 00:30:07,120 Speaker 1: gonna hit you and instead of having it hit you, 595 00:30:07,280 --> 00:30:10,800 Speaker 1: have it flow around you instead. So the common analogy 596 00:30:10,840 --> 00:30:13,400 Speaker 1: that's used is think about a rock that's in a river. 597 00:30:13,800 --> 00:30:17,000 Speaker 1: The water is flowing, it flows around the rock, and downstream, 598 00:30:17,040 --> 00:30:19,280 Speaker 1: it's not easy to tell that the rock was there 599 00:30:19,440 --> 00:30:21,760 Speaker 1: all the water is flowing basically in the same direction 600 00:30:21,840 --> 00:30:24,360 Speaker 1: as it was before. So if you could somehow get 601 00:30:24,480 --> 00:30:28,520 Speaker 1: light to bend around you and then reform the original 602 00:30:28,560 --> 00:30:32,000 Speaker 1: image that was behind you, you could effectively be invisible. 603 00:30:32,200 --> 00:30:34,320 Speaker 1: Out of all the technologies you've talked about so far, 604 00:30:34,440 --> 00:30:37,600 Speaker 1: this one seems the most sci fi to me. Really 605 00:30:37,640 --> 00:30:39,480 Speaker 1: hard for me to wrap my brain around this being 606 00:30:39,480 --> 00:30:43,160 Speaker 1: a thing that we could actually do in a lab. Well, 607 00:30:43,200 --> 00:30:45,080 Speaker 1: it's really cool and there's a lot of people working 608 00:30:45,080 --> 00:30:47,719 Speaker 1: on this kind of stuff, and there's a few different 609 00:30:47,720 --> 00:30:50,840 Speaker 1: technological approaches that people are taking, but it's the one 610 00:30:50,880 --> 00:30:53,680 Speaker 1: that while most science fiction e actually I think is 611 00:30:53,800 --> 00:30:56,480 Speaker 1: most realistic. So while I'm a physicist, I'm not an 612 00:30:56,480 --> 00:30:59,280 Speaker 1: expert in optics. So I reached out to an expert, 613 00:30:59,480 --> 00:31:02,840 Speaker 1: Greg word, and asked him to talk to us about 614 00:31:02,880 --> 00:31:06,680 Speaker 1: this new promising technology. My name is Greg Gaboram, a 615 00:31:06,880 --> 00:31:10,960 Speaker 1: professor of optical science and engineering at the University of 616 00:31:10,960 --> 00:31:17,800 Speaker 1: North Carolina and Charlotte, and my specialty is theoretical classical optics. Basically, 617 00:31:18,400 --> 00:31:21,200 Speaker 1: light is a wave. So I was really grateful to 618 00:31:21,240 --> 00:31:23,720 Speaker 1: Greg for giving us some time and talking about the 619 00:31:23,800 --> 00:31:26,720 Speaker 1: prospects of invisibility. So I asked him what he thought 620 00:31:26,760 --> 00:31:30,760 Speaker 1: was the most promising technology. The approach that really gained 621 00:31:30,760 --> 00:31:34,160 Speaker 1: prominence starting with some papers in two thousand six is 622 00:31:34,160 --> 00:31:37,680 Speaker 1: the idea of of invisibility cloak. That it's not like 623 00:31:37,760 --> 00:31:40,720 Speaker 1: a Harry Potter cloak, where it's a flexible material that 624 00:31:40,760 --> 00:31:44,240 Speaker 1: you can strape over yourself. It's a structure, probably a 625 00:31:44,320 --> 00:31:48,600 Speaker 1: rigid structure made of some very specialized material that we 626 00:31:48,680 --> 00:31:51,640 Speaker 1: don't completely know how to make yet, that would guide 627 00:31:51,720 --> 00:31:55,880 Speaker 1: light around some hidden interior region and send it along 628 00:31:55,920 --> 00:31:58,760 Speaker 1: its way as if it had encountered nothing at all. 629 00:31:58,920 --> 00:32:02,240 Speaker 1: One analogy that was used by those original authors in 630 00:32:02,320 --> 00:32:05,760 Speaker 1: two thousand six was like water going around a rock 631 00:32:05,840 --> 00:32:08,920 Speaker 1: and a stream, which, amusingly is also a description that 632 00:32:08,960 --> 00:32:11,880 Speaker 1: a science fiction author used in the nineteen thirties used 633 00:32:11,880 --> 00:32:14,680 Speaker 1: exactly the same analogy. I think the best way to 634 00:32:14,760 --> 00:32:17,680 Speaker 1: understand this is to think about the way you might 635 00:32:17,760 --> 00:32:20,760 Speaker 1: see this otherwise in your life, Like if you're on 636 00:32:20,800 --> 00:32:23,239 Speaker 1: a road on a hot day, you can see this 637 00:32:23,400 --> 00:32:26,240 Speaker 1: reflection on the horizon. It's sort of like the desert 638 00:32:26,320 --> 00:32:29,040 Speaker 1: mirage effect, where it looks like there's a puddle of 639 00:32:29,040 --> 00:32:31,400 Speaker 1: water in the desert, and what's happening there is just 640 00:32:31,480 --> 00:32:34,480 Speaker 1: that light is bending, Like you're not actually seeing water 641 00:32:34,680 --> 00:32:37,000 Speaker 1: on the highway or water in the desert. Where you're 642 00:32:37,000 --> 00:32:40,000 Speaker 1: seeing is a reflection of the sky because the air 643 00:32:40,200 --> 00:32:43,240 Speaker 1: that's just above the hot sand creates this effect where 644 00:32:43,320 --> 00:32:46,000 Speaker 1: light from the sky gets bent towards your eye. What 645 00:32:46,080 --> 00:32:48,840 Speaker 1: you're seeing is an image. You're not actually seeing the reality, 646 00:32:48,960 --> 00:32:51,680 Speaker 1: so it fools your eye into thinking there's a puddle 647 00:32:51,680 --> 00:32:54,160 Speaker 1: of water on the ground. So the same basic idea 648 00:32:54,200 --> 00:32:56,880 Speaker 1: of finding a way of bending the light around something. 649 00:32:57,240 --> 00:33:00,040 Speaker 1: Is the physics behind this approach, and so why and 650 00:33:00,200 --> 00:33:01,920 Speaker 1: we do this in a lab, it won't have the 651 00:33:02,000 --> 00:33:04,600 Speaker 1: like wibbly look that you get over, you know, a 652 00:33:04,680 --> 00:33:07,240 Speaker 1: highway on a hot day. It'll it'll be a lot 653 00:33:07,240 --> 00:33:09,960 Speaker 1: more controlled than crisp. Is that the idea, that's the goal. 654 00:33:10,360 --> 00:33:13,080 Speaker 1: And people are doing this in several different ways, which 655 00:33:13,080 --> 00:33:15,160 Speaker 1: I think is pretty cool. There's like really three or 656 00:33:15,200 --> 00:33:19,040 Speaker 1: four totally different approaches to bending the light around you. 657 00:33:19,400 --> 00:33:22,040 Speaker 1: Number one, which is sort of science fictionally cool but 658 00:33:22,200 --> 00:33:26,960 Speaker 1: probably not very practical, is using nanotubes. Nanotubes are these 659 00:33:27,040 --> 00:33:30,080 Speaker 1: really weird constructions of carbon that were invented a couple 660 00:33:30,160 --> 00:33:33,160 Speaker 1: of decades ago. These carbon nanotubes have lots of really 661 00:33:33,200 --> 00:33:36,360 Speaker 1: interesting electrical and other kinds of effects, and they're very 662 00:33:36,440 --> 00:33:38,880 Speaker 1: very thin, and they're very very strong. Actually, they're like 663 00:33:39,000 --> 00:33:42,239 Speaker 1: one candidate for how you could build a space elevator. Right. 664 00:33:42,520 --> 00:33:44,800 Speaker 1: They're super strong and thin and they can hold a 665 00:33:44,800 --> 00:33:48,120 Speaker 1: lot of weight. But also they have weird optical properties 666 00:33:48,200 --> 00:33:51,440 Speaker 1: and when you heat them just right, light bends around them. 667 00:33:51,480 --> 00:33:54,000 Speaker 1: And just this way that we're talking about that blows 668 00:33:54,000 --> 00:33:55,880 Speaker 1: my mind. Because they're just carbon, it seems like such 669 00:33:55,920 --> 00:33:58,200 Speaker 1: a simple molecule, but yeah, it would be very cool 670 00:33:58,200 --> 00:34:00,479 Speaker 1: if it could do this. Yeah, and that's the base principle. 671 00:34:00,520 --> 00:34:04,760 Speaker 1: It's a simple molecule, but complex arrangements of simple molecules 672 00:34:04,960 --> 00:34:08,279 Speaker 1: can have really interesting optical effects. I think the best 673 00:34:08,320 --> 00:34:10,960 Speaker 1: example is like silver. Take a piece of silver and 674 00:34:11,040 --> 00:34:13,600 Speaker 1: you polish it. What do you get? You get a mirror, right, 675 00:34:13,800 --> 00:34:16,439 Speaker 1: silver makes like some of the best mirrors out there. 676 00:34:16,760 --> 00:34:20,240 Speaker 1: But take that same silver, chop it up into nanoparticles 677 00:34:20,280 --> 00:34:22,879 Speaker 1: and suspended in water. What does it look like? It's 678 00:34:23,000 --> 00:34:25,680 Speaker 1: jet black. In fact, a lot of the negatives that 679 00:34:25,719 --> 00:34:28,880 Speaker 1: you see the black in that comes basically from suspended 680 00:34:28,920 --> 00:34:31,960 Speaker 1: silver nanoparticles and so like the same materials, just the 681 00:34:32,000 --> 00:34:35,400 Speaker 1: same silver can have very different optical properties based on 682 00:34:35,520 --> 00:34:38,120 Speaker 1: how you build it because the optical effects depend on 683 00:34:38,320 --> 00:34:41,000 Speaker 1: how light interacts with it and the surfaces inside and 684 00:34:41,280 --> 00:34:45,040 Speaker 1: exact arrangement of electromagnetic fields can really change how that happens. 685 00:34:45,080 --> 00:34:48,480 Speaker 1: So that's the key idea. Yeah, but nanotubes aren't really 686 00:34:48,560 --> 00:34:50,920 Speaker 1: very practical. They did a little demonstration where they have 687 00:34:50,920 --> 00:34:53,360 Speaker 1: a really small bit of it and it kind of works, 688 00:34:53,360 --> 00:34:55,440 Speaker 1: which is cool sort of in principle, but you've got 689 00:34:55,560 --> 00:34:57,759 Speaker 1: to heat this thing up and only really works for 690 00:34:57,800 --> 00:35:00,680 Speaker 1: like a very very thin sheet. So if you want 691 00:35:00,719 --> 00:35:04,640 Speaker 1: to wear a very hot, thin sheet of nanotubes, then 692 00:35:04,719 --> 00:35:07,080 Speaker 1: you know, maybe you could look a little invisible, but 693 00:35:07,120 --> 00:35:09,360 Speaker 1: it's not something that can easily be scaled up about 694 00:35:09,400 --> 00:35:11,840 Speaker 1: how hot are we talking. We're talking like a hundred 695 00:35:11,840 --> 00:35:15,839 Speaker 1: degrees celsius. Yeah, that's probably know, that's not gonna work out. 696 00:35:15,920 --> 00:35:18,239 Speaker 1: It reminds me of that Nathan for You episode where 697 00:35:18,239 --> 00:35:20,320 Speaker 1: he puts on the chili suit and then he realizes 698 00:35:20,480 --> 00:35:22,600 Speaker 1: he doesn't want to walk around in a suit of 699 00:35:22,600 --> 00:35:27,680 Speaker 1: hot chili. And now there's another approach which has gained 700 00:35:27,719 --> 00:35:30,640 Speaker 1: a lot of attention on the internet, probably because they 701 00:35:30,640 --> 00:35:33,040 Speaker 1: put the name quantum in it for no good reason. 702 00:35:33,360 --> 00:35:37,520 Speaker 1: And that's this thing called the Quantum stealth invisibility cloak. 703 00:35:37,800 --> 00:35:40,919 Speaker 1: And if you just google invisibility technology, probably the top 704 00:35:40,960 --> 00:35:44,200 Speaker 1: ten videos you'll see are people demonstrating this stuff. And 705 00:35:44,280 --> 00:35:47,160 Speaker 1: at first glance, it looks pretty cool. It's like a 706 00:35:47,200 --> 00:35:49,640 Speaker 1: sheet of stuff and if you stand behind it, people 707 00:35:49,719 --> 00:35:51,480 Speaker 1: can't see you. And he's like a guy and he's 708 00:35:51,520 --> 00:35:53,439 Speaker 1: holding a sheet of the stuff. It's like a real 709 00:35:53,520 --> 00:35:55,279 Speaker 1: size sheet of it. And when you look at the sheet. 710 00:35:55,320 --> 00:35:57,600 Speaker 1: You only see the thing behind him, the wall behind him. 711 00:35:57,640 --> 00:35:59,680 Speaker 1: You don't see his body, so it's like you see 712 00:35:59,680 --> 00:36:01,440 Speaker 1: the top of his body and then the middle of 713 00:36:01,440 --> 00:36:03,560 Speaker 1: its invisible, and then you see his legs. So it 714 00:36:03,600 --> 00:36:08,040 Speaker 1: appears pretty impressive at the beginning, So it's not actually 715 00:36:08,040 --> 00:36:11,040 Speaker 1: really invisibility in my mind, because the way it works 716 00:36:11,160 --> 00:36:14,359 Speaker 1: is that actually has like a grooved surface. It's sort 717 00:36:14,400 --> 00:36:17,239 Speaker 1: of like you know holograms that have these grooves on 718 00:36:17,280 --> 00:36:19,239 Speaker 1: them and they give you like a weird image as 719 00:36:19,280 --> 00:36:21,400 Speaker 1: you look at them, or you know, like a wall 720 00:36:21,480 --> 00:36:23,920 Speaker 1: of glass that has like a rough edge to it, 721 00:36:23,960 --> 00:36:26,280 Speaker 1: so it doesn't project the image behind it very clearly. 722 00:36:26,440 --> 00:36:30,200 Speaker 1: These have these lenticular lenses. He's like very narrow grooves. 723 00:36:30,400 --> 00:36:32,959 Speaker 1: So it happens is that when the light passes through it, 724 00:36:32,960 --> 00:36:35,279 Speaker 1: it gets spread out, but only in one direction. So, 725 00:36:35,320 --> 00:36:38,400 Speaker 1: for example, the light that from his body he's standing 726 00:36:38,400 --> 00:36:41,160 Speaker 1: behind this invisibility shield, the light from his body gets 727 00:36:41,200 --> 00:36:44,240 Speaker 1: smeared out in one direction, and so you actually still 728 00:36:44,400 --> 00:36:47,560 Speaker 1: can see him through the invisibility shield. It's just that 729 00:36:47,640 --> 00:36:49,680 Speaker 1: his body has been smeared out, so you don't really 730 00:36:49,760 --> 00:36:53,040 Speaker 1: notice him anymore. It's like diluted his effect by smearing 731 00:36:53,040 --> 00:36:55,120 Speaker 1: it in one direction. So it sounds like for some 732 00:36:55,200 --> 00:36:57,680 Speaker 1: of these ideas, it really sounds like if they're used 733 00:36:57,760 --> 00:36:59,840 Speaker 1: very rarely, you might be able to get away with 734 00:36:59,840 --> 00:37:01,960 Speaker 1: it people aren't expecting it. But if it becomes a 735 00:37:02,000 --> 00:37:04,000 Speaker 1: popular tech, it's just not going to work because you've 736 00:37:04,040 --> 00:37:05,839 Speaker 1: noticed the smeared guy. If you need to look out 737 00:37:05,840 --> 00:37:08,000 Speaker 1: for him, that's right. And then once people know that 738 00:37:08,040 --> 00:37:09,880 Speaker 1: it's out there, they'll be on the lookout for it, 739 00:37:09,920 --> 00:37:12,440 Speaker 1: and it wouldn't work very well anymore. And this, for example, 740 00:37:12,480 --> 00:37:15,160 Speaker 1: it's pretty easy to fail. It works at some levels, 741 00:37:15,160 --> 00:37:16,880 Speaker 1: but if you're looking at it from the right angle 742 00:37:17,120 --> 00:37:19,520 Speaker 1: or actually from the wrong angle, then it actually makes 743 00:37:19,520 --> 00:37:25,560 Speaker 1: what's behind the cloak look bigger and larger. It amplifies it. Awkward, Yeah, 744 00:37:25,640 --> 00:37:28,520 Speaker 1: awkward if you're like sneaking up on your enemy, you know, 745 00:37:28,600 --> 00:37:31,920 Speaker 1: for military applications, and all of a sudden like boom, 746 00:37:31,960 --> 00:37:33,960 Speaker 1: you know, they can see you. That could be embarrassing. 747 00:37:34,080 --> 00:37:36,160 Speaker 1: But maybe this could work in like the animal Kingdom, 748 00:37:36,200 --> 00:37:38,239 Speaker 1: you know, where you like try to look bigger than 749 00:37:38,280 --> 00:37:42,320 Speaker 1: your enemies. Maybe you could give like small chickens this, uh, 750 00:37:42,400 --> 00:37:44,560 Speaker 1: this device, and then they could be you know, top 751 00:37:44,560 --> 00:37:47,200 Speaker 1: of the pecking order. Yeah, exactly. So in my mind, 752 00:37:47,280 --> 00:37:49,480 Speaker 1: this is basically just the same thing that like a 753 00:37:49,520 --> 00:37:52,480 Speaker 1: fuzzy shower door does. You know, like somebody's taking a 754 00:37:52,560 --> 00:37:55,279 Speaker 1: shower and the door is fuzzy, you can't really see them, right, 755 00:37:55,280 --> 00:37:57,080 Speaker 1: It basically blurs them out. This is that, but it 756 00:37:57,200 --> 00:38:00,000 Speaker 1: just sort of like maximized like maximum blurs. You don't 757 00:38:00,200 --> 00:38:03,600 Speaker 1: really noticed that they're there. But again, anybody who's really 758 00:38:03,600 --> 00:38:05,480 Speaker 1: on the lookout is going to tell. So this guy 759 00:38:05,480 --> 00:38:08,759 Speaker 1: has been trying to sell his quantum stealth technology to 760 00:38:08,800 --> 00:38:11,120 Speaker 1: the military for like a decade, and they have been 761 00:38:11,120 --> 00:38:14,719 Speaker 1: buying it, I guess for a reason. Yeah, yeah, and 762 00:38:14,800 --> 00:38:18,120 Speaker 1: so now he's offering it to the general public. So anyway, 763 00:38:18,200 --> 00:38:20,800 Speaker 1: it's cool. It's definitely not something I could have invented. 764 00:38:20,920 --> 00:38:23,839 Speaker 1: It's pretty simple stuff, you know, achieves something of what 765 00:38:23,920 --> 00:38:26,160 Speaker 1: you want to do. But again, it's not real invisibility. 766 00:38:26,200 --> 00:38:30,120 Speaker 1: It's not really bending the image around the person. Yeah, 767 00:38:30,120 --> 00:38:32,360 Speaker 1: I certainly wouldn't want to go to war with a 768 00:38:32,520 --> 00:38:36,759 Speaker 1: sort of smudgy mirror in front of me, smugy piece 769 00:38:36,800 --> 00:38:40,920 Speaker 1: of glass. So the most promising approach came after a 770 00:38:40,920 --> 00:38:44,080 Speaker 1: breakthrough in two thousand and six when people realize that 771 00:38:44,400 --> 00:38:47,680 Speaker 1: if you made a really weird new kind of material, 772 00:38:48,040 --> 00:38:51,439 Speaker 1: a substance called a meta material, then you could use 773 00:38:51,480 --> 00:38:54,520 Speaker 1: that to bend the light around an object because had 774 00:38:54,520 --> 00:38:59,280 Speaker 1: a really strange optical property of having a negative index 775 00:38:59,400 --> 00:39:02,000 Speaker 1: of ref action. What does that mean? So index with 776 00:39:02,120 --> 00:39:05,560 Speaker 1: refraction tells you how a material bends light. So, for example, 777 00:39:05,880 --> 00:39:08,479 Speaker 1: you know that when light hits glass, it passes through, 778 00:39:08,520 --> 00:39:11,000 Speaker 1: but it also gets bent. Right, that's how prisms work. 779 00:39:11,200 --> 00:39:13,239 Speaker 1: Or if you look at somebody who's half in the 780 00:39:13,239 --> 00:39:15,399 Speaker 1: pool and half out of the pool, the bottom half 781 00:39:15,480 --> 00:39:18,560 Speaker 1: looks like shifted in one direction. That's because the light 782 00:39:18,680 --> 00:39:21,560 Speaker 1: bends a little bit as it passes through the material. Well, 783 00:39:21,560 --> 00:39:24,720 Speaker 1: that's an index of refraction. It's usually measures like one 784 00:39:25,040 --> 00:39:28,239 Speaker 1: or above. But if you had a negative index of refraction, 785 00:39:28,360 --> 00:39:31,560 Speaker 1: the light would do something really weird. Instead of entering 786 00:39:31,600 --> 00:39:33,919 Speaker 1: at an angle and just changing its angle a little bit, 787 00:39:34,000 --> 00:39:36,160 Speaker 1: it would enter and then go the other direction, so 788 00:39:36,160 --> 00:39:38,440 Speaker 1: it would make like more than a ninety degree turn 789 00:39:38,800 --> 00:39:42,680 Speaker 1: and bend really weirdly inside the material. Well this is 790 00:39:42,680 --> 00:39:46,120 Speaker 1: cool because if you wrap an object in this negative 791 00:39:46,200 --> 00:39:49,399 Speaker 1: index of refraction material, then it basically bends the light 792 00:39:49,520 --> 00:39:52,040 Speaker 1: in such a way that it passes around the object, 793 00:39:52,120 --> 00:39:54,160 Speaker 1: and then when it comes back out, it's going in 794 00:39:54,280 --> 00:39:58,279 Speaker 1: exactly the direction was originally. So the idea was, oh, 795 00:39:58,719 --> 00:40:01,800 Speaker 1: maybe if you had this negative index of refraction material, 796 00:40:01,920 --> 00:40:06,320 Speaker 1: it could actually achieve this invisibility. Yeah. Well, the coolest 797 00:40:06,320 --> 00:40:08,520 Speaker 1: part of the story is that the idea comes from 798 00:40:08,560 --> 00:40:11,120 Speaker 1: like the sixties. Somebody wrote a paper in the sixties 799 00:40:11,120 --> 00:40:14,120 Speaker 1: being like, hmm, this seems impossible, but if you could 800 00:40:14,160 --> 00:40:16,719 Speaker 1: make a material that had this weird property nobody's ever 801 00:40:16,760 --> 00:40:20,080 Speaker 1: seen before, then you could achieve invisibility. Ignored for four 802 00:40:20,120 --> 00:40:23,200 Speaker 1: decades until in two thousand and six, people realized if 803 00:40:23,239 --> 00:40:26,160 Speaker 1: you could create this meta material, and a meta material 804 00:40:26,400 --> 00:40:29,040 Speaker 1: is a material that has a property that you don't 805 00:40:29,080 --> 00:40:32,600 Speaker 1: usually find in nature, like negative index of refraction. They 806 00:40:32,600 --> 00:40:34,399 Speaker 1: realized there might be a way to do it by 807 00:40:34,480 --> 00:40:37,880 Speaker 1: constructing a really strange material. And so, for example, to 808 00:40:37,960 --> 00:40:40,880 Speaker 1: have this material with really thin layers of silver and 809 00:40:40,880 --> 00:40:44,120 Speaker 1: then really thin layers of magnesium fluoride. And there's another 810 00:40:44,120 --> 00:40:47,080 Speaker 1: way to do it, making these like silver nano wires. 811 00:40:47,239 --> 00:40:48,919 Speaker 1: And the way to understand it and to think about 812 00:40:48,960 --> 00:40:52,320 Speaker 1: it is to remember that light is just an electromagnetic wave. 813 00:40:52,560 --> 00:40:55,040 Speaker 1: So what we're talking about is bending light. We're talking 814 00:40:55,080 --> 00:40:58,560 Speaker 1: about electromagnetic interactions. So you just create these atoms in 815 00:40:58,560 --> 00:41:02,520 Speaker 1: a special arrange mints, so they have these weird electromagnetic 816 00:41:02,520 --> 00:41:05,319 Speaker 1: properties that bend light in whatever way you want. And 817 00:41:05,320 --> 00:41:07,960 Speaker 1: this is possible now and it wasn't fifty years ago, 818 00:41:08,000 --> 00:41:11,000 Speaker 1: because now we're much better like building these nano materials, 819 00:41:11,000 --> 00:41:14,719 Speaker 1: like engineering super duper small structures and then making a 820 00:41:14,840 --> 00:41:17,440 Speaker 1: large sample of them. So has anyone tried making a 821 00:41:17,480 --> 00:41:20,000 Speaker 1: cloak out of this or is this still pretty preliminary? 822 00:41:20,040 --> 00:41:22,879 Speaker 1: It's still pretty preliminary. Like they got it to work, 823 00:41:22,880 --> 00:41:25,480 Speaker 1: and where they built basically was like a cylinder of 824 00:41:25,560 --> 00:41:28,080 Speaker 1: this stuff, and you can't see the cylinder, Like you 825 00:41:28,160 --> 00:41:29,799 Speaker 1: shine a bunch of light at it, and the light 826 00:41:29,840 --> 00:41:32,920 Speaker 1: comes out the other side going exactly the same direction 827 00:41:33,120 --> 00:41:37,200 Speaker 1: that it entered. Yeah, it's like basically invisible, but it 828 00:41:37,239 --> 00:41:41,960 Speaker 1: only works in certain wavelengths. So far it works in microwaves, 829 00:41:42,040 --> 00:41:44,439 Speaker 1: or maybe it works in radio waves. It doesn't work 830 00:41:44,440 --> 00:41:46,719 Speaker 1: in visible light. You can still see this thing in 831 00:41:46,719 --> 00:41:48,840 Speaker 1: the visible light, but you know, if somebody shines a 832 00:41:48,880 --> 00:41:51,719 Speaker 1: microwave laser at it or shoots radio waves at it, 833 00:41:51,840 --> 00:41:55,719 Speaker 1: then it's invisible to that kind of radiation. So this 834 00:41:55,760 --> 00:41:58,680 Speaker 1: would not require the like giant batteries and computers that 835 00:41:58,719 --> 00:42:00,600 Speaker 1: we were talking about for the other one. But would 836 00:42:00,640 --> 00:42:03,920 Speaker 1: it cover your own heat or is that another problem? Yeah? 837 00:42:03,960 --> 00:42:06,040 Speaker 1: That is another problem. But you're right, this thing is 838 00:42:06,040 --> 00:42:08,080 Speaker 1: like static. It doesn't need to be powered. It's just 839 00:42:08,120 --> 00:42:10,560 Speaker 1: like a structure of material that bends light in a 840 00:42:10,600 --> 00:42:13,000 Speaker 1: certain way. And if you're inside of it, you're like 841 00:42:13,040 --> 00:42:16,520 Speaker 1: walking around with this cylinder of meta material. Then imprinciple, 842 00:42:16,640 --> 00:42:19,320 Speaker 1: people can't see you in the microwave or the radio wave. 843 00:42:19,440 --> 00:42:22,320 Speaker 1: But you're right, it doesn't mask your heat, right, doesn't 844 00:42:22,320 --> 00:42:24,319 Speaker 1: like absorb all of your heat. I don't know how 845 00:42:24,320 --> 00:42:26,520 Speaker 1: you could do that, right, because you're putting out a 846 00:42:26,520 --> 00:42:28,120 Speaker 1: lot of heat and if there's no way to vent it, 847 00:42:28,280 --> 00:42:31,480 Speaker 1: you're just going to basically roast inside this thing. Yeah, 848 00:42:31,560 --> 00:42:33,759 Speaker 1: and is that the state of the art right now? 849 00:42:33,800 --> 00:42:36,480 Speaker 1: Is that the fanciest solution we have? And that is 850 00:42:36,480 --> 00:42:38,759 Speaker 1: basically what we've achieved. And by we, I mean you know, 851 00:42:38,920 --> 00:42:41,520 Speaker 1: the whole physics community actually working hard on it, and 852 00:42:41,560 --> 00:42:43,919 Speaker 1: me just sort of like reading articles about it. But hey, 853 00:42:43,960 --> 00:42:46,840 Speaker 1: that's a contribution. And people are trying to think about 854 00:42:46,840 --> 00:42:49,680 Speaker 1: how to make it work for visible light. Also, like, 855 00:42:49,840 --> 00:42:52,719 Speaker 1: is it possible to build a material which could do 856 00:42:52,760 --> 00:42:55,920 Speaker 1: this for all kinds of frequencies? And that's sort of 857 00:42:55,960 --> 00:42:58,359 Speaker 1: the next generation. That's what people are working on now. 858 00:42:58,680 --> 00:43:01,040 Speaker 1: And I read a paper from lad Ear that has 859 00:43:01,080 --> 00:43:04,040 Speaker 1: a really cool title on it. It talks about developing 860 00:43:04,080 --> 00:43:08,799 Speaker 1: a tachyonic invisibility cloak. What the heck is that? Yeah, 861 00:43:08,840 --> 00:43:13,280 Speaker 1: attack eon is something that travels faster than the speed 862 00:43:13,360 --> 00:43:15,319 Speaker 1: of light. So we talked in the podcast once about 863 00:43:15,320 --> 00:43:17,920 Speaker 1: like what is a tacky on It's a hypothetical particle 864 00:43:17,960 --> 00:43:19,759 Speaker 1: that might travel fast than the speed of light. We 865 00:43:19,800 --> 00:43:22,560 Speaker 1: don't think it exists. It violates special relativity. But the 866 00:43:22,640 --> 00:43:25,120 Speaker 1: phrase tachi on it, it doesn't just exist in star 867 00:43:25,200 --> 00:43:28,360 Speaker 1: trek is referred to anytime something moves faster than the 868 00:43:28,400 --> 00:43:30,520 Speaker 1: speed of light. And so that's pretty cool. And the 869 00:43:30,640 --> 00:43:33,360 Speaker 1: idea behind this was they did a bunch of theoretical 870 00:43:33,440 --> 00:43:37,200 Speaker 1: calculations to figure out could you make a material which 871 00:43:37,360 --> 00:43:41,040 Speaker 1: number one passes all frequencies of light through it in 872 00:43:41,120 --> 00:43:43,719 Speaker 1: the same way that the meta material does, right, having 873 00:43:43,760 --> 00:43:46,640 Speaker 1: a negative index of refraction, but works for all kinds 874 00:43:46,680 --> 00:43:50,399 Speaker 1: of frequencies, not just microwave or radio wave. And number two, 875 00:43:50,480 --> 00:43:53,000 Speaker 1: and this is an important and tricky bit that also 876 00:43:53,120 --> 00:43:56,880 Speaker 1: didn't have a time delay. One problem with bending the 877 00:43:57,040 --> 00:43:59,560 Speaker 1: image around you is that then the path length of 878 00:43:59,600 --> 00:44:02,800 Speaker 1: the image is longer. It takes more time for the 879 00:44:02,880 --> 00:44:05,440 Speaker 1: light to travel around you than if it had flowed 880 00:44:05,520 --> 00:44:08,800 Speaker 1: through you. Somebody with like really sensitive devices might be 881 00:44:08,880 --> 00:44:11,480 Speaker 1: able to measure that time difference and deduce that you're there. 882 00:44:11,800 --> 00:44:14,439 Speaker 1: So they wanted to develop a cloak that was take 883 00:44:14,480 --> 00:44:17,719 Speaker 1: ionic so that the light traveled on that longer path 884 00:44:18,280 --> 00:44:21,160 Speaker 1: was going faster effectively than the speed of light, in 885 00:44:21,280 --> 00:44:23,279 Speaker 1: such a way that it emerged on the other side 886 00:44:23,320 --> 00:44:26,160 Speaker 1: of the material exactly the same time it otherwise would 887 00:44:26,200 --> 00:44:28,960 Speaker 1: have if you weren't there. And is that possible? Well, 888 00:44:29,040 --> 00:44:31,600 Speaker 1: they claim that it is, and they do all these calculations, 889 00:44:31,680 --> 00:44:33,840 Speaker 1: and your first thought must be like, hold on a second, 890 00:44:33,880 --> 00:44:37,960 Speaker 1: what about special relativity? Right? Doesn't that violate causality? How 891 00:44:38,040 --> 00:44:40,080 Speaker 1: could you possibly get from one side of material to 892 00:44:40,160 --> 00:44:42,839 Speaker 1: the other and do it faster than the speed of light. Well, 893 00:44:42,920 --> 00:44:46,120 Speaker 1: as usual in physics, there are loopholes, and if you 894 00:44:46,360 --> 00:44:49,279 Speaker 1: read the rules really really carefully, you can discover that 895 00:44:49,280 --> 00:44:52,320 Speaker 1: there might be ways around them. For example, what actually 896 00:44:52,680 --> 00:44:55,719 Speaker 1: is the rule about traveling faster than the speed of light, 897 00:44:56,000 --> 00:44:59,560 Speaker 1: it's that no piece of information can go through space 898 00:45:00,000 --> 00:45:03,279 Speaker 1: faster than light travels through space. So, for example, we've 899 00:45:03,280 --> 00:45:05,680 Speaker 1: talked in the podcast before about how that doesn't mean 900 00:45:05,800 --> 00:45:08,480 Speaker 1: that you can't get from one place to another faster 901 00:45:08,600 --> 00:45:11,920 Speaker 1: than light could if you could like bend space itself. Right, 902 00:45:12,000 --> 00:45:14,360 Speaker 1: That's like how warp drives and wormholes work. So the 903 00:45:14,480 --> 00:45:17,160 Speaker 1: spirit there is to look for loopholes, and the loophole 904 00:45:17,280 --> 00:45:20,239 Speaker 1: here is to think about how the wave propagates through 905 00:45:20,320 --> 00:45:23,799 Speaker 1: this stuff. And there's two actually different velocities to think 906 00:45:23,840 --> 00:45:27,280 Speaker 1: about when you think about the wave. There's the phase velocity. 907 00:45:27,400 --> 00:45:30,480 Speaker 1: That's like how an individual piece of the stuff is moving, 908 00:45:30,640 --> 00:45:33,160 Speaker 1: like the thing that's doing the waving. How fast is 909 00:45:33,239 --> 00:45:35,960 Speaker 1: that being actually moving? And that can't move fast in 910 00:45:36,000 --> 00:45:37,799 Speaker 1: the speed of light because it's the thing and moves 911 00:45:37,880 --> 00:45:40,759 Speaker 1: through space. But then there's the group velocity. The group 912 00:45:40,840 --> 00:45:43,320 Speaker 1: velocity tells us about like how the speed of the 913 00:45:43,400 --> 00:45:47,120 Speaker 1: whole wavefront is moving. Is not actually a requirement for 914 00:45:47,200 --> 00:45:50,480 Speaker 1: the group velocity to move slower than the speed of light. 915 00:45:50,800 --> 00:45:53,479 Speaker 1: So this is pretty tricky. So I asked our friend 916 00:45:53,520 --> 00:45:55,759 Speaker 1: Greg Gaber to see if he could explain it to us. 917 00:45:56,239 --> 00:45:58,880 Speaker 1: If you have a material that has optical gain that 918 00:45:59,000 --> 00:46:02,160 Speaker 1: you can pump so has energy built into it, you 919 00:46:02,200 --> 00:46:05,120 Speaker 1: can basically have a wave that effectively moves faster than 920 00:46:05,160 --> 00:46:08,120 Speaker 1: the vacuum speed of light, kind of like an avalanche. 921 00:46:08,160 --> 00:46:10,680 Speaker 1: That the center of gravity of an avalanche can move 922 00:46:10,800 --> 00:46:13,799 Speaker 1: faster than the front of the avalanche because it's picking 923 00:46:13,920 --> 00:46:17,320 Speaker 1: up extra rocks as it goes and leaving some behind. 924 00:46:18,160 --> 00:46:20,000 Speaker 1: So the shape of the wave itself is moving, so 925 00:46:20,080 --> 00:46:22,480 Speaker 1: you're sort of like losing the back edge of the 926 00:46:22,560 --> 00:46:25,160 Speaker 1: wave and adding new stuff to the front edge of 927 00:46:25,200 --> 00:46:28,480 Speaker 1: the wave, which effectively makes the wave move faster. So 928 00:46:28,600 --> 00:46:30,640 Speaker 1: there's a lot of technical stuff in this paper. If 929 00:46:30,680 --> 00:46:32,640 Speaker 1: you're really interested, I suggest you look it up. But 930 00:46:32,719 --> 00:46:35,520 Speaker 1: the basic idea is that you use some loopholes and 931 00:46:35,600 --> 00:46:38,080 Speaker 1: trickery to try to get that light to pass through 932 00:46:38,160 --> 00:46:40,520 Speaker 1: the material in such a way that it appears with 933 00:46:40,680 --> 00:46:43,480 Speaker 1: no time delay on the other side. So is this 934 00:46:43,640 --> 00:46:46,760 Speaker 1: something that is working on a computer but not working 935 00:46:47,239 --> 00:46:50,719 Speaker 1: in real life yet. Yeah, this is just a calculation 936 00:46:51,040 --> 00:46:53,600 Speaker 1: and they've done in simulation, and they say, if you 937 00:46:53,680 --> 00:46:55,880 Speaker 1: could build this thing and it has these properties, then 938 00:46:55,920 --> 00:46:58,719 Speaker 1: you could actually achieve that that's exciting, and the people 939 00:46:58,760 --> 00:47:00,840 Speaker 1: I've talked to you said, wow, this is a cool idea. 940 00:47:01,280 --> 00:47:03,239 Speaker 1: And in the paper they don't actually build it, right, 941 00:47:03,239 --> 00:47:05,200 Speaker 1: they just talk about how you might be able to 942 00:47:05,800 --> 00:47:07,480 Speaker 1: and to do that you need this thing called a 943 00:47:07,640 --> 00:47:11,479 Speaker 1: semiconductor optical amplifier, and that's what Bird was talking about. 944 00:47:11,520 --> 00:47:14,000 Speaker 1: It needs some energy, like requires a little bit of 945 00:47:14,080 --> 00:47:16,759 Speaker 1: optical pumping. So this is a technology that people are 946 00:47:16,800 --> 00:47:19,120 Speaker 1: working on, have developed. They haven't quite made it do 947 00:47:19,239 --> 00:47:21,000 Speaker 1: this thing yet, but it's sort of like, you know, 948 00:47:21,040 --> 00:47:24,240 Speaker 1: at the theoretical stage, like, hey, this idea might be possible. 949 00:47:24,520 --> 00:47:26,200 Speaker 1: Let's get some folks in the lab and try to 950 00:47:26,200 --> 00:47:29,280 Speaker 1: actually build this thing. Awesome. I hope it gets funded. 951 00:47:30,840 --> 00:47:34,200 Speaker 1: Probably dark, but would be all about it. So I 952 00:47:34,280 --> 00:47:36,440 Speaker 1: think that covers most of the topics of like how 953 00:47:36,560 --> 00:47:38,920 Speaker 1: you could do invisibility and what people are doing and 954 00:47:38,960 --> 00:47:42,080 Speaker 1: the progress that's been made. And I'm pretty excited that 955 00:47:42,200 --> 00:47:44,600 Speaker 1: people are making progress. Like we've gone from this is 956 00:47:44,640 --> 00:47:47,880 Speaker 1: a ridiculous thing in science fiction to hey, here's how 957 00:47:47,960 --> 00:47:50,279 Speaker 1: you might actually be able to do it, to like, look, 958 00:47:50,360 --> 00:47:53,120 Speaker 1: we have some basic working prototypes that you know, don't 959 00:47:53,160 --> 00:47:56,319 Speaker 1: satisfy all the requirements, but satisfy some of them. I'm 960 00:47:56,360 --> 00:47:59,360 Speaker 1: torn between thinking it's totally awesome that we're making progress 961 00:47:59,440 --> 00:48:01,799 Speaker 1: on this, being excited about seeing the world of sci 962 00:48:01,880 --> 00:48:04,239 Speaker 1: fi come to real life, and also being a little 963 00:48:04,239 --> 00:48:06,920 Speaker 1: bit uncomfortable about a world where this technology exists and 964 00:48:07,000 --> 00:48:09,600 Speaker 1: people can go sneaking around. So I guess, I guess 965 00:48:09,640 --> 00:48:12,319 Speaker 1: I can see the good and bed of this well. 966 00:48:12,400 --> 00:48:14,920 Speaker 1: As Professor Gooberg what he thought the prospects were for 967 00:48:15,040 --> 00:48:17,759 Speaker 1: invisibility in the future, if you want to make a 968 00:48:17,840 --> 00:48:21,759 Speaker 1: device that would work very well to hide things from 969 00:48:21,880 --> 00:48:25,400 Speaker 1: visible light, you would need to design something that has 970 00:48:25,440 --> 00:48:29,359 Speaker 1: a controllable structure on the order of the wavelength of light, 971 00:48:29,480 --> 00:48:33,080 Speaker 1: which means very very small sizes, and we don't quite 972 00:48:33,120 --> 00:48:35,760 Speaker 1: know how to do that yet. So we might start 973 00:48:35,880 --> 00:48:41,719 Speaker 1: seeing interesting applications not in visible light. But something that 974 00:48:41,800 --> 00:48:44,239 Speaker 1: I've noticed is there's a trend of looking at how 975 00:48:44,320 --> 00:48:47,680 Speaker 1: can we use this same cloaking technology for other types 976 00:48:47,719 --> 00:48:51,440 Speaker 1: of waves. People have talked about making earthquake cloaks or 977 00:48:51,960 --> 00:48:56,319 Speaker 1: cloaks that guide water waves around structures, And I love 978 00:48:56,440 --> 00:48:59,000 Speaker 1: his idea there that we could use invisibility for more 979 00:48:59,040 --> 00:49:01,840 Speaker 1: than just like sneaking around and snooping on people, but 980 00:49:02,000 --> 00:49:05,160 Speaker 1: for like making objects invisibles to other kinds of waves, 981 00:49:05,239 --> 00:49:08,360 Speaker 1: like earthquakes or water waves or sound waves. That's a 982 00:49:08,480 --> 00:49:12,319 Speaker 1: really cool idea. So maybe one day the whole Bay 983 00:49:12,360 --> 00:49:18,640 Speaker 1: Area will be cloaked in some sort of earthquake invisibility device. Alright, 984 00:49:18,800 --> 00:49:21,840 Speaker 1: So that's the science of invisibility. Thanks for taking this 985 00:49:22,000 --> 00:49:24,800 Speaker 1: trip with us to understand how people are pushing the 986 00:49:24,920 --> 00:49:28,880 Speaker 1: forefront of physics to make science fiction real. Thanks tune 987 00:49:28,880 --> 00:49:31,399 Speaker 1: in next time and don't forget. If you have something 988 00:49:31,480 --> 00:49:33,279 Speaker 1: you'd like us to break down, send it to us 989 00:49:33,360 --> 00:49:37,000 Speaker 1: to questions at Daniel and Jorge dot com. Thanks for listening, 990 00:49:44,880 --> 00:49:47,720 Speaker 1: Thanks for listening, and remember that Daniel and Jorge explained. 991 00:49:47,760 --> 00:49:50,680 Speaker 1: The Universe is a production of I Heart Radio or 992 00:49:50,800 --> 00:49:53,680 Speaker 1: more podcast for my heart Radio, visit the I heart 993 00:49:53,800 --> 00:49:57,359 Speaker 1: Radio app, Apple Podcasts, or wherever you listen to your 994 00:49:57,440 --> 00:50:03,640 Speaker 1: favorite shows. M