1 00:00:04,160 --> 00:00:07,200 Speaker 1: Get in tech with technology with tech Stuff from half 2 00:00:07,240 --> 00:00:13,600 Speaker 1: stuff works dot com. Hey there, and welcome to tech Stuff. 3 00:00:13,680 --> 00:00:16,960 Speaker 1: I'm your host, Jonathan Strickland. I'm an executive producer here 4 00:00:17,000 --> 00:00:19,840 Speaker 1: at how Stuff Works in a love all things tech. 5 00:00:19,880 --> 00:00:23,159 Speaker 1: And not only do I love all things tech, I 6 00:00:23,320 --> 00:00:27,680 Speaker 1: also love science fiction. Those who have listened to the 7 00:00:27,680 --> 00:00:29,680 Speaker 1: show for a while know that I have a deep 8 00:00:29,720 --> 00:00:32,479 Speaker 1: love of science fiction, and no small part due to 9 00:00:32,479 --> 00:00:35,520 Speaker 1: my parents, who are both science fiction fans and authors. 10 00:00:36,159 --> 00:00:39,199 Speaker 1: And one of my favorite gadgets in science fiction is 11 00:00:39,280 --> 00:00:43,199 Speaker 1: the cloaking device. Now, the earliest example I can remember 12 00:00:43,520 --> 00:00:47,839 Speaker 1: from my own personal experience is from Star Trek, because 13 00:00:47,920 --> 00:00:51,279 Speaker 1: the Klingons and the Romulans in Star Trek had access 14 00:00:51,320 --> 00:00:55,680 Speaker 1: to technology that could render their ships not just undetectable 15 00:00:55,720 --> 00:01:02,120 Speaker 1: by sensors, but completely invisible. So this goes beyond stealth technology, 16 00:01:02,160 --> 00:01:06,160 Speaker 1: which uses materials and architecture to confound devices like radar. 17 00:01:06,200 --> 00:01:08,920 Speaker 1: I'll talk more about that later, but this would be 18 00:01:08,959 --> 00:01:13,720 Speaker 1: a technology that could turn an entire spacecraft completely invisible, 19 00:01:13,840 --> 00:01:18,080 Speaker 1: allowing light and other electromagnetic energy to bend around it 20 00:01:18,160 --> 00:01:22,320 Speaker 1: in such a way as to seemingly pass through it entirely, 21 00:01:22,760 --> 00:01:25,440 Speaker 1: so you can think kind of like light in this sense, 22 00:01:25,480 --> 00:01:30,000 Speaker 1: being like flowing water. Imagine a stream of water flowing downhill, 23 00:01:30,480 --> 00:01:34,000 Speaker 1: and you place a rock in the middle of that stream, 24 00:01:34,040 --> 00:01:36,759 Speaker 1: and the water will part around that rock and come 25 00:01:36,800 --> 00:01:39,160 Speaker 1: back together on the other side. And so if you're 26 00:01:39,160 --> 00:01:41,640 Speaker 1: just a little further downstream, you would never know there 27 00:01:41,680 --> 00:01:43,640 Speaker 1: was a rock there in the first place, because the 28 00:01:43,640 --> 00:01:45,760 Speaker 1: way the water is flowing, it looks like it's been 29 00:01:45,800 --> 00:01:48,600 Speaker 1: moving in a straight line the whole time. That's simply 30 00:01:49,000 --> 00:01:52,400 Speaker 1: the same kind of concept for cloaking devices, except instead 31 00:01:52,400 --> 00:01:58,320 Speaker 1: of water, we're talking about electromagnetic radiation. That's the basic premise, right, 32 00:01:58,720 --> 00:02:01,880 Speaker 1: It somehow is able to bend energy so that it 33 00:02:01,920 --> 00:02:05,760 Speaker 1: flows around the object and continues on its original trajectory 34 00:02:05,880 --> 00:02:08,240 Speaker 1: as if nothing were there to begin with. To an 35 00:02:08,240 --> 00:02:11,400 Speaker 1: outside observer relying upon this type of energy to quote 36 00:02:11,440 --> 00:02:14,760 Speaker 1: unquote see the cloaked object, it would seem as if 37 00:02:14,800 --> 00:02:17,800 Speaker 1: nothing were there at all. When it comes to science fiction, 38 00:02:18,160 --> 00:02:22,600 Speaker 1: writers tend to rely upon terms that sound vaguely futuristic 39 00:02:22,600 --> 00:02:27,200 Speaker 1: and scientific, but typically they don't actually mean anything. Most 40 00:02:27,240 --> 00:02:31,040 Speaker 1: of them rely on fictional energies or materials, but there 41 00:02:31,080 --> 00:02:34,720 Speaker 1: are real world examples of cloaking devices that I would 42 00:02:34,720 --> 00:02:37,520 Speaker 1: like to talk about. Before I jump into that, I 43 00:02:37,560 --> 00:02:41,440 Speaker 1: need to make one thing very clear. The cloaking devices 44 00:02:41,600 --> 00:02:45,840 Speaker 1: and technologies I'll be covering will not turn objects invisible 45 00:02:45,880 --> 00:02:48,240 Speaker 1: to the naked eye. They don't work at that end 46 00:02:48,280 --> 00:02:51,280 Speaker 1: of the electromagnetic spectrum, at least not the ones that 47 00:02:51,320 --> 00:02:53,680 Speaker 1: are on the higher tech end of it. Some of 48 00:02:53,680 --> 00:02:57,080 Speaker 1: them use optical illusions to make it seem that way. 49 00:02:57,120 --> 00:03:01,000 Speaker 1: This little fact, however, sometimes gets lost in reporting of 50 00:03:01,120 --> 00:03:04,639 Speaker 1: cloaking technology. The headlines are too good to say new 51 00:03:04,680 --> 00:03:08,960 Speaker 1: cloaking device makes it a reality, or sometimes the information 52 00:03:09,080 --> 00:03:11,959 Speaker 1: is included in the reporting and then everyone gets a 53 00:03:11,960 --> 00:03:14,120 Speaker 1: little bummed out about it because it's not a quote 54 00:03:14,160 --> 00:03:18,280 Speaker 1: unquote real cloaking device. I'll also cover a few technologies 55 00:03:18,320 --> 00:03:22,280 Speaker 1: that create this illusion of a cloaking device under specific criteria, 56 00:03:22,360 --> 00:03:25,040 Speaker 1: because the solution is actually a kind of clever and 57 00:03:25,160 --> 00:03:29,280 Speaker 1: a good place to start is with stealth technology. Now 58 00:03:29,320 --> 00:03:32,840 Speaker 1: I've covered stealth tech in a previous episode of Tech Stuff, 59 00:03:33,120 --> 00:03:35,960 Speaker 1: but I'm gonna go and cover some of it again 60 00:03:36,080 --> 00:03:38,360 Speaker 1: right here. I'm just gonna go really light on history, 61 00:03:38,440 --> 00:03:40,480 Speaker 1: because you can listen to the other episode and get 62 00:03:40,520 --> 00:03:43,040 Speaker 1: the full story. I just want to talk about how 63 00:03:43,120 --> 00:03:47,760 Speaker 1: stealth fighters and stealth bombers work from that stealth perspective. First, 64 00:03:48,360 --> 00:03:50,680 Speaker 1: I'm sure you've seen pictures of these sorts of vehicles 65 00:03:50,720 --> 00:03:52,720 Speaker 1: and you might notice right away that they don't appear 66 00:03:52,760 --> 00:03:55,600 Speaker 1: to be invisible. You can kind of sort of totally 67 00:03:55,640 --> 00:04:00,960 Speaker 1: see them. One makes them stealth isn't there ability to 68 00:04:01,160 --> 00:04:03,480 Speaker 1: disappear in front of your very eyes, because they don't 69 00:04:03,600 --> 00:04:09,000 Speaker 1: have that, but rather their ability to evade detection via radar. Now, 70 00:04:09,120 --> 00:04:15,480 Speaker 1: radar works like echolocation. Electromagnetic symbol signals rather beam out 71 00:04:15,760 --> 00:04:19,480 Speaker 1: from a transmitter, and then those signals collide with an 72 00:04:19,480 --> 00:04:23,040 Speaker 1: object like a jet. Some of those signals bounce off 73 00:04:23,080 --> 00:04:26,400 Speaker 1: the jet and bounce back towards the transmitter. You also, 74 00:04:26,520 --> 00:04:29,760 Speaker 1: besides the transmitter, have a receiver, and the receiver picks 75 00:04:29,880 --> 00:04:34,520 Speaker 1: up these returning signals and registers that there's an aircraft 76 00:04:34,720 --> 00:04:38,680 Speaker 1: present in the airspace. If there's a change in wavelength 77 00:04:38,960 --> 00:04:41,599 Speaker 1: the radio In the radio signals, you can also deduce 78 00:04:41,640 --> 00:04:44,480 Speaker 1: if the aircraft is moving toward you or away from you. 79 00:04:45,000 --> 00:04:48,320 Speaker 1: If the radio waves are longer than they were when 80 00:04:48,360 --> 00:04:51,160 Speaker 1: you blasted them out, that means the objects moving away. 81 00:04:51,400 --> 00:04:54,760 Speaker 1: If they're elongated. In other words, if the wavelengths are 82 00:04:54,839 --> 00:04:59,120 Speaker 1: shorter the object is coming toward you. This is the 83 00:04:59,200 --> 00:05:01,840 Speaker 1: Doppler of act. It's the same sort of thing you 84 00:05:01,920 --> 00:05:06,440 Speaker 1: might experience if a car with a siren blasting drives 85 00:05:06,480 --> 00:05:09,359 Speaker 1: past you. It sounds higher pitched as the car is 86 00:05:09,400 --> 00:05:12,040 Speaker 1: coming towards you, and lower pitched as the car is 87 00:05:12,120 --> 00:05:14,360 Speaker 1: moving away from you. And that's because the sound waves 88 00:05:14,360 --> 00:05:18,120 Speaker 1: themselves are being compressed in front of the vehicle as 89 00:05:18,160 --> 00:05:21,400 Speaker 1: it moves towards you, and they're elongated as the vehicle 90 00:05:21,480 --> 00:05:24,159 Speaker 1: moves away from you. Same sort of thing can happen 91 00:05:24,160 --> 00:05:27,000 Speaker 1: with electromagnetic waves, and like I said, it's called the 92 00:05:27,000 --> 00:05:30,400 Speaker 1: Doppler effect. Also, by looking at the delay between when 93 00:05:30,440 --> 00:05:34,480 Speaker 1: the radio waves blasted out from the transmitter and when 94 00:05:34,560 --> 00:05:37,600 Speaker 1: the returning waves were picked up by the receiver, you 95 00:05:37,640 --> 00:05:40,480 Speaker 1: know how far away the aircraft is because the radio 96 00:05:40,520 --> 00:05:44,760 Speaker 1: waves travel at a constant speed. So by knowing how 97 00:05:44,800 --> 00:05:49,560 Speaker 1: much time has passed, you know how how far away 98 00:05:49,800 --> 00:05:52,359 Speaker 1: the aircraft is. Right, you just measure the amount of 99 00:05:52,360 --> 00:05:54,480 Speaker 1: time that has passed and then you do a quick 100 00:05:54,520 --> 00:05:58,000 Speaker 1: calculation to say, well, it traveled x distance in this 101 00:05:58,040 --> 00:06:01,000 Speaker 1: amount of time. Let's take half of that at because 102 00:06:01,040 --> 00:06:04,320 Speaker 1: the signals traveled out and then they traveled back, so 103 00:06:04,480 --> 00:06:07,479 Speaker 1: half of the full length of travel time is how 104 00:06:07,520 --> 00:06:11,880 Speaker 1: far away the aircraft is, roughly speaking, So stealth technology 105 00:06:12,080 --> 00:06:17,240 Speaker 1: is all about foiling that process. The two major methods 106 00:06:17,720 --> 00:06:21,880 Speaker 1: involved creating a radar absorbent surface, something that is very 107 00:06:21,920 --> 00:06:27,120 Speaker 1: efficient at absorbing electromagnetic radiation, and then making sure that 108 00:06:27,200 --> 00:06:31,680 Speaker 1: the aircraft has a particular shape to reflect any other 109 00:06:31,800 --> 00:06:36,400 Speaker 1: radio waves in different directions than the origin source. The 110 00:06:36,480 --> 00:06:39,680 Speaker 1: absorbent surface is a composite material that's made of lots 111 00:06:39,680 --> 00:06:43,920 Speaker 1: of different lightweight stuff that's really efficient at absorbing radio energy. 112 00:06:43,960 --> 00:06:46,839 Speaker 1: If the aircraft absorbs the radio waves from a radio antenna, 113 00:06:47,279 --> 00:06:50,120 Speaker 1: nothing would bounce back and nothing would get picked up 114 00:06:50,160 --> 00:06:53,360 Speaker 1: by the receiver. So if you had a perfect absorbent material, 115 00:06:54,040 --> 00:06:56,960 Speaker 1: it would just soak in all those radio waves. Nothing 116 00:06:57,000 --> 00:06:59,960 Speaker 1: would ever return, so it would never show up on radar. 117 00:07:00,240 --> 00:07:03,320 Speaker 1: But we don't have anything that's quite that perfect. The 118 00:07:03,400 --> 00:07:06,120 Speaker 1: plane's shape plays a really big part in this as well, 119 00:07:06,600 --> 00:07:09,040 Speaker 1: because a radio wave will bounce off of surfaces and 120 00:07:09,080 --> 00:07:11,720 Speaker 1: return at an angle, just as if you were to bounce, 121 00:07:11,720 --> 00:07:14,840 Speaker 1: say a cue ball inside a pool table. You know, 122 00:07:14,920 --> 00:07:18,280 Speaker 1: if you choose different angles. When you're bouncing the cue ball, 123 00:07:18,520 --> 00:07:20,320 Speaker 1: it's going to react in a different way. It's going 124 00:07:20,360 --> 00:07:23,800 Speaker 1: to bounce off in a different direction. Um And once 125 00:07:23,840 --> 00:07:26,720 Speaker 1: you know that relationship, then you can start to design 126 00:07:26,800 --> 00:07:30,920 Speaker 1: surfaces to bounce those radio waves off in directions that 127 00:07:30,960 --> 00:07:33,880 Speaker 1: are not going to go back toward the receiver. The 128 00:07:33,880 --> 00:07:36,240 Speaker 1: shape of stealth vehicles tends to include a lot of 129 00:07:36,440 --> 00:07:40,800 Speaker 1: curved surfaces that seemingly wonky angles. Sometimes you'll get some 130 00:07:40,920 --> 00:07:44,520 Speaker 1: very flat surfaces as well, but they'll be in odd 131 00:07:45,280 --> 00:07:47,840 Speaker 1: positions relative to one another. And this is all to 132 00:07:47,920 --> 00:07:51,360 Speaker 1: try and foil those radio waves, to make them bounce 133 00:07:51,400 --> 00:07:54,080 Speaker 1: in a way that's not going to go back to 134 00:07:54,120 --> 00:07:58,160 Speaker 1: where the receiver is. So the electromagnetic radiation does not 135 00:07:58,600 --> 00:08:02,520 Speaker 1: pass through the air craft, it doesn't bend around it 136 00:08:02,600 --> 00:08:04,720 Speaker 1: the way you would say a cloaking device would do, 137 00:08:05,280 --> 00:08:08,720 Speaker 1: but it does allow you to have a way of 138 00:08:08,800 --> 00:08:12,440 Speaker 1: eluding radar detection. So it's not really the same sort 139 00:08:12,480 --> 00:08:15,800 Speaker 1: of technology that you would find in science fiction. Now, 140 00:08:15,800 --> 00:08:19,280 Speaker 1: there are other ways you can simulate a cloaking device, 141 00:08:19,480 --> 00:08:21,600 Speaker 1: such as a method that has been used in several 142 00:08:21,640 --> 00:08:24,680 Speaker 1: marketing campaigns, and that as to use a series of 143 00:08:24,760 --> 00:08:29,760 Speaker 1: cameras and screens to simulate a cloaking device. The concept 144 00:08:29,880 --> 00:08:33,080 Speaker 1: is pretty simple. You start with an object. Let's say 145 00:08:33,160 --> 00:08:37,720 Speaker 1: it's a Mercedes Benz F Cell concept vehicle, because Mercedes 146 00:08:37,760 --> 00:08:40,960 Speaker 1: actually did do this as a marketing stunt back in 147 00:08:41,040 --> 00:08:43,760 Speaker 1: two thousand twelve. The F Cell, by the way, was 148 00:08:43,920 --> 00:08:47,280 Speaker 1: a fuel cell prototype vehicle, and I've talked all about 149 00:08:47,280 --> 00:08:51,760 Speaker 1: fuel cells in other episodes. Pretty fascinating technology anyway. Imagine 150 00:08:51,800 --> 00:08:54,960 Speaker 1: that you cover one full side of this vehicle, let's 151 00:08:54,960 --> 00:08:58,800 Speaker 1: say the driver's side of the vehicle, with a mesh 152 00:08:58,920 --> 00:09:00,880 Speaker 1: that has a bunch of l e d s in 153 00:09:00,960 --> 00:09:04,640 Speaker 1: it to act as a screen, so the side of 154 00:09:04,640 --> 00:09:07,680 Speaker 1: the car turns into a low resolution l e ED 155 00:09:07,880 --> 00:09:10,840 Speaker 1: television screen. On the other side of the vehicle, you 156 00:09:10,920 --> 00:09:14,160 Speaker 1: mount a camera and the camera captures everything that's on 157 00:09:14,320 --> 00:09:16,480 Speaker 1: that side of the vehicle. So it's facing out from 158 00:09:16,480 --> 00:09:19,400 Speaker 1: the passenger side, so it would be the same kind 159 00:09:19,400 --> 00:09:21,760 Speaker 1: of point of view as a passenger would have if 160 00:09:21,800 --> 00:09:24,880 Speaker 1: he or she was looking directly out of their window. 161 00:09:25,960 --> 00:09:30,000 Speaker 1: The video feed you pick up from this camera gets 162 00:09:30,040 --> 00:09:33,439 Speaker 1: fed directly to the other side, to the l e 163 00:09:33,559 --> 00:09:38,439 Speaker 1: ED screen side of the vehicle, and it displays whatever 164 00:09:38,480 --> 00:09:42,760 Speaker 1: the cameras have picked up, so you end up getting 165 00:09:43,200 --> 00:09:46,120 Speaker 1: this illusion. If you stand on the screen side of 166 00:09:46,120 --> 00:09:49,800 Speaker 1: the vehicle, it's almost like you're looking through it, though 167 00:09:49,800 --> 00:09:52,400 Speaker 1: at a lower resolution than reality, so it looks a 168 00:09:52,440 --> 00:09:55,160 Speaker 1: little jankie. Although you could argue that's kind of like 169 00:09:55,200 --> 00:09:58,040 Speaker 1: a cloaking effect you see in some science fiction shows 170 00:09:58,080 --> 00:10:01,280 Speaker 1: and movies where you've got that little shimmery effect. It's 171 00:10:01,360 --> 00:10:03,640 Speaker 1: kind of like that, but less cool than that. Not 172 00:10:03,760 --> 00:10:08,040 Speaker 1: so predator. It's a little more uh noticeable. I've seen 173 00:10:08,080 --> 00:10:10,800 Speaker 1: similar setups to make an effect in costumes that make 174 00:10:10,840 --> 00:10:14,000 Speaker 1: it look like a person has a hole straight through 175 00:10:14,040 --> 00:10:16,760 Speaker 1: their torso. It's a pretty cool thing to do. It's 176 00:10:16,760 --> 00:10:20,160 Speaker 1: actually really easy if you've got two iPads. For example, 177 00:10:20,720 --> 00:10:23,600 Speaker 1: Uh they typically will wear a screen on their chest, 178 00:10:24,360 --> 00:10:26,720 Speaker 1: and then you can put a camera on your back 179 00:10:27,360 --> 00:10:31,520 Speaker 1: and the camera captures live video from whatever is going 180 00:10:31,559 --> 00:10:36,000 Speaker 1: on behind you, feeds it to the screen that's hanging 181 00:10:36,040 --> 00:10:39,000 Speaker 1: on front of your torso, and you cut a hole 182 00:10:39,040 --> 00:10:42,720 Speaker 1: in a shirt so that it it goes right around 183 00:10:42,720 --> 00:10:45,600 Speaker 1: the screen and the screen is showing everything that's happening 184 00:10:45,600 --> 00:10:47,680 Speaker 1: behind you. So the illusion is that you've got a 185 00:10:47,720 --> 00:10:50,400 Speaker 1: hole in your torso and people can look right through 186 00:10:50,440 --> 00:10:53,360 Speaker 1: it and see what's happening on the other side. Uh. 187 00:10:53,480 --> 00:10:55,120 Speaker 1: Like I said, you could actually do this in a 188 00:10:55,120 --> 00:10:58,320 Speaker 1: pretty easy way. I saw a clever video that used 189 00:10:58,360 --> 00:11:01,160 Speaker 1: a pair of iPad two tablet to make this effect 190 00:11:01,240 --> 00:11:04,480 Speaker 1: on both sides. The guy who published the video's name 191 00:11:04,520 --> 00:11:07,200 Speaker 1: is Mark Rober. He published the video on YouTube in 192 00:11:07,240 --> 00:11:10,040 Speaker 1: October two thousand eleven, so you can actually find this 193 00:11:10,160 --> 00:11:11,800 Speaker 1: video if you want to see how he did it. 194 00:11:12,280 --> 00:11:15,240 Speaker 1: But he said he used two iPad two's, one to 195 00:11:15,280 --> 00:11:18,839 Speaker 1: face out in front and one to face out in back. 196 00:11:19,400 --> 00:11:22,520 Speaker 1: So the but the screens were facing outward on both sides. 197 00:11:22,559 --> 00:11:24,560 Speaker 1: One facing one had you know, the back of the 198 00:11:24,559 --> 00:11:27,240 Speaker 1: iPad two was against his chest. The other one had 199 00:11:27,280 --> 00:11:29,520 Speaker 1: the back of the second iPad two against his back. 200 00:11:30,240 --> 00:11:31,920 Speaker 1: And what he did was he just set up a 201 00:11:31,920 --> 00:11:36,080 Speaker 1: FaceTime call between the two iPads, so each iPad was 202 00:11:36,120 --> 00:11:40,280 Speaker 1: showing the screen of the other iPads camera and by 203 00:11:40,320 --> 00:11:43,720 Speaker 1: doing that, you just have this live feed on either side. 204 00:11:43,800 --> 00:11:46,160 Speaker 1: So it worked on either side of the person. You 205 00:11:46,160 --> 00:11:48,640 Speaker 1: could stand in front of them and you're actually looking 206 00:11:49,000 --> 00:11:51,480 Speaker 1: at the hole that's showing on showing what's going on 207 00:11:51,520 --> 00:11:53,920 Speaker 1: behind the person, or you could be behind them, and 208 00:11:53,920 --> 00:11:55,880 Speaker 1: you'd be looking through the hole and you see what's 209 00:11:55,920 --> 00:11:57,840 Speaker 1: going on in front of that person, so you get 210 00:11:57,840 --> 00:12:00,880 Speaker 1: this illusion that you have a hole going through a 211 00:12:00,920 --> 00:12:03,400 Speaker 1: solid Torso it's great if you want to do a 212 00:12:03,440 --> 00:12:08,959 Speaker 1: creepy zombie style character at Halloween. I've always wanted to 213 00:12:09,000 --> 00:12:11,400 Speaker 1: do this, but I've never actually gone out to buy 214 00:12:11,400 --> 00:12:14,600 Speaker 1: a couple of iPads just to do a costume. It 215 00:12:14,600 --> 00:12:16,360 Speaker 1: seems like it might be a little much for me, 216 00:12:16,440 --> 00:12:20,040 Speaker 1: but still pretty neat. However, again, that's not a true 217 00:12:20,040 --> 00:12:22,560 Speaker 1: cloaking device. I don't think anyone would ever argue that. 218 00:12:22,720 --> 00:12:26,120 Speaker 1: And for one thing, any set up where you've got 219 00:12:26,160 --> 00:12:29,679 Speaker 1: a screen and a camera means that you really only 220 00:12:29,720 --> 00:12:34,920 Speaker 1: have one side prepared to be quote unquote cloaked. So 221 00:12:35,000 --> 00:12:38,240 Speaker 1: if you're on the other side of the device or 222 00:12:38,280 --> 00:12:41,120 Speaker 1: the structure or whatever it is, you would totally see 223 00:12:41,559 --> 00:12:45,480 Speaker 1: the object or the person standing there because you would 224 00:12:45,520 --> 00:12:49,559 Speaker 1: be on the camera side, not the screen side. It's 225 00:12:49,600 --> 00:12:52,160 Speaker 1: kind of like being backstage in a show. You see 226 00:12:52,160 --> 00:12:57,000 Speaker 1: how everything works, so it's not truly cloaking. But next, 227 00:12:57,440 --> 00:13:00,839 Speaker 1: we're gonna talk about bending light and something you can 228 00:13:00,880 --> 00:13:05,400 Speaker 1: actually do. We can bend light optical lenses do that, 229 00:13:05,760 --> 00:13:09,200 Speaker 1: so if you wear glasses or contacts, you rely on 230 00:13:09,360 --> 00:13:12,880 Speaker 1: something that bends light already, and I talked about the 231 00:13:12,880 --> 00:13:16,280 Speaker 1: physics of optical lenses in an episode not too far back. 232 00:13:16,320 --> 00:13:19,679 Speaker 1: But if you're clever and you use the right sequence 233 00:13:19,840 --> 00:13:23,200 Speaker 1: of lenses at the proper distance from one another, you 234 00:13:23,200 --> 00:13:26,880 Speaker 1: can create an optical illusion equal to a type of cloaking. 235 00:13:27,360 --> 00:13:31,079 Speaker 1: And that's the secret behind the original Rochester Cloak, so 236 00:13:31,120 --> 00:13:34,160 Speaker 1: called because it was developed at the University of Rochester. 237 00:13:34,760 --> 00:13:37,440 Speaker 1: Now I'll talk more about their approach to cloaking in 238 00:13:37,480 --> 00:13:40,600 Speaker 1: just a second, but first let's take a quick break 239 00:13:40,760 --> 00:13:50,839 Speaker 1: to thank our sponsor. The version of the Rochester Cloak 240 00:13:50,960 --> 00:13:54,839 Speaker 1: I studied had four lenses arranged in a straight line 241 00:13:55,040 --> 00:13:58,760 Speaker 1: with several inches separating each lens. So think of it 242 00:13:58,800 --> 00:14:02,840 Speaker 1: as lens one, two, three, four, And let's say that 243 00:14:02,880 --> 00:14:06,480 Speaker 1: for the purposes of this description, that the lens closest 244 00:14:06,640 --> 00:14:09,839 Speaker 1: to someone who's going to look through the Rochester Cloak 245 00:14:10,520 --> 00:14:14,079 Speaker 1: is lens number one. The furthest lens from the viewer 246 00:14:14,360 --> 00:14:17,400 Speaker 1: is lens number four. Now, in the demonstration I viewed 247 00:14:18,200 --> 00:14:24,120 Speaker 1: the uh the the backdrop for this was a grid pattern, 248 00:14:24,320 --> 00:14:27,120 Speaker 1: So there was actually a grid pattern in the very back, 249 00:14:27,880 --> 00:14:31,040 Speaker 1: and the purpose of that was to provide a reference 250 00:14:31,240 --> 00:14:34,360 Speaker 1: so that when you passed things between the lenses in 251 00:14:34,440 --> 00:14:37,160 Speaker 1: order to create this cloaking effect, you would still see 252 00:14:37,160 --> 00:14:39,280 Speaker 1: the grid pattern in the background, and it gives this 253 00:14:39,360 --> 00:14:43,080 Speaker 1: illusion that you have an unbroken uh line of sight 254 00:14:43,200 --> 00:14:45,840 Speaker 1: even when an object is passing between the lenses. So 255 00:14:46,280 --> 00:14:49,280 Speaker 1: a casual glance through the lenses, it makes it seem 256 00:14:49,360 --> 00:14:52,040 Speaker 1: like light has just passed through the series of lenses 257 00:14:52,040 --> 00:14:55,680 Speaker 1: without bending. Like from from lens for two lens one, 258 00:14:56,080 --> 00:14:58,280 Speaker 1: the effect you get is that the light has just 259 00:14:58,320 --> 00:15:01,640 Speaker 1: traveled straight through those lenses, because the grids in the 260 00:15:01,680 --> 00:15:05,520 Speaker 1: back remains straight, and that becomes your reference point. Right 261 00:15:05,520 --> 00:15:07,200 Speaker 1: You're looking at the grids and you're thinking, well, the 262 00:15:07,240 --> 00:15:10,000 Speaker 1: lines look straight, so the light's not really being bent 263 00:15:10,400 --> 00:15:13,680 Speaker 1: by these lenses. At least that's the optical illusion I have. 264 00:15:15,240 --> 00:15:18,640 Speaker 1: But what is really happening is some light gymnastics. And 265 00:15:18,800 --> 00:15:23,080 Speaker 1: I don't mean low impact gymnastics. I mean gymnastics involving light. 266 00:15:23,640 --> 00:15:27,000 Speaker 1: Each lens bends the light in a slightly different way, 267 00:15:27,520 --> 00:15:30,920 Speaker 1: concentrating or spreading out the light, so that if you 268 00:15:30,960 --> 00:15:34,960 Speaker 1: were to place a small object between Lens one and 269 00:15:35,120 --> 00:15:38,840 Speaker 1: lens too, So the first two lenses it would look 270 00:15:38,880 --> 00:15:41,960 Speaker 1: as if you could see right through the object with 271 00:15:42,280 --> 00:15:46,000 Speaker 1: some limitations. The big limitation is that the cloaking effect 272 00:15:46,480 --> 00:15:49,840 Speaker 1: only works on the edges of the viewing area of 273 00:15:49,880 --> 00:15:52,240 Speaker 1: the lens. So if you think of the lens as 274 00:15:52,240 --> 00:15:55,000 Speaker 1: a circle, the closer you get to the center of 275 00:15:55,040 --> 00:15:58,720 Speaker 1: that circle, the closer you're getting to the point where 276 00:15:58,720 --> 00:16:00,880 Speaker 1: you're going to be able to actually see that object. 277 00:16:00,880 --> 00:16:04,640 Speaker 1: But if it's on the the edge of the center, 278 00:16:05,080 --> 00:16:08,320 Speaker 1: then it seems like you can look right through the object. 279 00:16:09,080 --> 00:16:11,920 Speaker 1: So uh, it's because the light is being bent in 280 00:16:11,920 --> 00:16:15,360 Speaker 1: such a way that that light is concentrated on the 281 00:16:15,440 --> 00:16:19,800 Speaker 1: center of lens number one before that lens actually spreads 282 00:16:19,800 --> 00:16:22,600 Speaker 1: the light out again towards your eye. And each of 283 00:16:22,600 --> 00:16:26,160 Speaker 1: these lenses was carefully selected so that it would manipulate 284 00:16:26,200 --> 00:16:30,320 Speaker 1: the light where it seems like you're looking at an 285 00:16:30,400 --> 00:16:33,600 Speaker 1: unaltered image. Right, it looks like you're looking at that 286 00:16:33,640 --> 00:16:36,600 Speaker 1: grid and the lines are straight. In fact, the way 287 00:16:36,640 --> 00:16:39,640 Speaker 1: that the light is being bent by the lens, if 288 00:16:39,680 --> 00:16:41,600 Speaker 1: you were to look through lens number two instead of 289 00:16:41,640 --> 00:16:45,120 Speaker 1: lens number one, the backdrop would look very different. It 290 00:16:45,160 --> 00:16:47,800 Speaker 1: wouldn't look like a grid of straight lines. It's because 291 00:16:47,800 --> 00:16:51,080 Speaker 1: each lens is bending light in a specific way that 292 00:16:51,160 --> 00:16:54,360 Speaker 1: you're able to create this effect. So it doesn't matter 293 00:16:54,720 --> 00:16:57,120 Speaker 1: if the object you put between lens one and lens 294 00:16:57,160 --> 00:17:01,000 Speaker 1: two is a pencil or a finger, it seems like 295 00:17:01,040 --> 00:17:04,320 Speaker 1: there is nothing there in front of you, or that 296 00:17:04,960 --> 00:17:07,720 Speaker 1: the middle of the object has disappeared, like if you 297 00:17:07,760 --> 00:17:10,760 Speaker 1: can see the object on either side of the lens, 298 00:17:10,800 --> 00:17:13,840 Speaker 1: like if it extends out to either edge, it would 299 00:17:13,880 --> 00:17:16,520 Speaker 1: look like the middle is just suddenly gone. But again, 300 00:17:16,560 --> 00:17:19,960 Speaker 1: this is all just through optics, so it's somewhat limited 301 00:17:20,280 --> 00:17:23,840 Speaker 1: as it's entirely dependent upon your frame of reference. It 302 00:17:24,200 --> 00:17:27,439 Speaker 1: depends upon the viewer looking through the lens. If you 303 00:17:27,480 --> 00:17:29,439 Speaker 1: were to step to the side and look at this 304 00:17:29,480 --> 00:17:33,320 Speaker 1: apparatus from ninety degrees on, you would observe that there's 305 00:17:33,320 --> 00:17:36,160 Speaker 1: no cloaking effect at all. The light your eyes would 306 00:17:36,160 --> 00:17:39,000 Speaker 1: detect has not passed through that array of lenses, so 307 00:17:39,040 --> 00:17:41,760 Speaker 1: all you would see is someone placing an object between 308 00:17:41,760 --> 00:17:44,199 Speaker 1: two lenses, and it would not disappear. It would just 309 00:17:44,240 --> 00:17:47,560 Speaker 1: be right there, so there'd be nothing special from your perspective. 310 00:17:47,960 --> 00:17:51,320 Speaker 1: There are similar projects that use cameras, mirrors, and displays 311 00:17:51,680 --> 00:17:55,000 Speaker 1: to create this type of illusion, but again they're dependent 312 00:17:55,080 --> 00:17:58,040 Speaker 1: upon your frame of reference and perspective. If you step 313 00:17:58,040 --> 00:18:02,000 Speaker 1: outside that frame of reference and truth settles in, then 314 00:18:02,040 --> 00:18:05,440 Speaker 1: you notice that the thing is not really invisible or transparent. 315 00:18:05,520 --> 00:18:08,320 Speaker 1: This is kind of like having a magician hide something 316 00:18:08,359 --> 00:18:11,760 Speaker 1: behind a little curtain, and because you're looking at the curtain, 317 00:18:11,840 --> 00:18:13,919 Speaker 1: you cannot see what's going on behind it. But if 318 00:18:13,960 --> 00:18:16,919 Speaker 1: you were watching from the side of the magician, you 319 00:18:16,920 --> 00:18:18,919 Speaker 1: can see how the trick was done, which is not 320 00:18:19,119 --> 00:18:21,920 Speaker 1: much fun, but it does show that the optical illusion 321 00:18:21,960 --> 00:18:25,960 Speaker 1: depends upon certain criteria to work, specifically where you are 322 00:18:26,040 --> 00:18:30,040 Speaker 1: looking from. In two thousand seventeen, Toyota applied for a 323 00:18:30,080 --> 00:18:35,240 Speaker 1: patent titled Apparatuses and Methods for making an Object Appear Transparent. 324 00:18:36,119 --> 00:18:38,359 Speaker 1: So was this a way to turn an entire car 325 00:18:38,480 --> 00:18:43,119 Speaker 1: invisible allah James Bond's Aston Martin v. Twelve Vanquished and 326 00:18:43,200 --> 00:18:47,600 Speaker 1: Die Another Day. Not quite. This is a system meant 327 00:18:47,680 --> 00:18:51,760 Speaker 1: to help the driver of the car. It's not meant 328 00:18:51,880 --> 00:18:56,359 Speaker 1: for people outside the vehicle. Toyota's approach is a method 329 00:18:56,440 --> 00:19:00,119 Speaker 1: to make certain features inside the car appear transparent to 330 00:19:00,160 --> 00:19:03,480 Speaker 1: the driver, so that the driver can have an unimpeded 331 00:19:03,560 --> 00:19:07,440 Speaker 1: view of the environment around the car. Specifically, the objects 332 00:19:07,440 --> 00:19:10,080 Speaker 1: that were meant to be turned transparent were the A 333 00:19:10,320 --> 00:19:13,880 Speaker 1: pillars inside the vehicle. Now, the pillars in a car 334 00:19:14,000 --> 00:19:18,240 Speaker 1: are the supports of a car's window area, sometimes also 335 00:19:18,280 --> 00:19:22,720 Speaker 1: called the greenhouse. Pillars are divided up as A, B, C, 336 00:19:23,160 --> 00:19:27,119 Speaker 1: and if the vehicle's big enough, sometimes D pillars. The 337 00:19:27,280 --> 00:19:30,240 Speaker 1: B pillars are sometimes called posts. Those are the ones 338 00:19:30,280 --> 00:19:32,960 Speaker 1: that are on the side of the vehicle. Uh. The 339 00:19:33,040 --> 00:19:35,280 Speaker 1: A pillars are the sections on either side of the 340 00:19:35,320 --> 00:19:38,080 Speaker 1: windshield that support the windshield and connect to the top 341 00:19:38,119 --> 00:19:41,600 Speaker 1: of the car in order to meet crash safety standards. 342 00:19:41,600 --> 00:19:44,480 Speaker 1: Those pillars can be pretty wide to provide the necessary 343 00:19:44,480 --> 00:19:47,720 Speaker 1: structural support, but that means they block some of your 344 00:19:47,800 --> 00:19:51,239 Speaker 1: view while you're driving. So it's that section of a 345 00:19:51,280 --> 00:19:56,159 Speaker 1: car that separates the front windshield from your side mirror 346 00:19:56,560 --> 00:20:00,439 Speaker 1: or your side window. Rather so that that poe, that 347 00:20:00,600 --> 00:20:03,320 Speaker 1: pillar is what Toyota was thinking about, like, how can 348 00:20:03,359 --> 00:20:06,080 Speaker 1: we make it so that you can see through that 349 00:20:06,200 --> 00:20:10,440 Speaker 1: pillar and thus have a better view out that side 350 00:20:10,440 --> 00:20:12,960 Speaker 1: of your vehicle, so that you really don't have an 351 00:20:13,000 --> 00:20:16,600 Speaker 1: impeded view from the front all the way over to 352 00:20:17,080 --> 00:20:20,320 Speaker 1: your side window. How do you get rid of that 353 00:20:20,400 --> 00:20:23,760 Speaker 1: gap from your vision. Well, according to the patent, Toyota's 354 00:20:23,880 --> 00:20:27,760 Speaker 1: system redirects light using mirrors so that the light projects 355 00:20:27,840 --> 00:20:30,840 Speaker 1: on the pillar itself, creating the illusion that the pillar 356 00:20:31,000 --> 00:20:34,879 Speaker 1: is transparent and removing that gap from your visibility. And 357 00:20:34,920 --> 00:20:37,840 Speaker 1: because it's a patent, anyone is free to look it 358 00:20:37,920 --> 00:20:41,320 Speaker 1: over and read about the technology Toyota developed. So if 359 00:20:41,359 --> 00:20:42,640 Speaker 1: you want to do it, if you want to read 360 00:20:42,680 --> 00:20:47,080 Speaker 1: about some pretty complicated concepts and optics, I have the 361 00:20:47,160 --> 00:20:49,560 Speaker 1: patent number for you. It is a long one, so 362 00:20:49,640 --> 00:20:54,680 Speaker 1: get ready. The patent application number is US two thousand, 363 00:20:54,800 --> 00:21:01,360 Speaker 1: seventeen zero two two seven seven eight one a one. 364 00:21:01,640 --> 00:21:04,200 Speaker 1: So if you put that into a patent search, you're 365 00:21:04,200 --> 00:21:06,000 Speaker 1: gonna pull this up and you can read all about 366 00:21:06,080 --> 00:21:11,359 Speaker 1: how Toyota proposes this technology be implemented. But what about 367 00:21:11,359 --> 00:21:13,919 Speaker 1: a cloak more in line with the invisibility cloak in 368 00:21:13,920 --> 00:21:17,640 Speaker 1: Harry Potter. In J. K. Rowling's books, characters make use 369 00:21:17,760 --> 00:21:21,320 Speaker 1: of the invisibility cloak to snoop in on important exposition. 370 00:21:21,880 --> 00:21:24,960 Speaker 1: And in that world it all works via magic, which 371 00:21:25,000 --> 00:21:27,919 Speaker 1: is great because there's no need to explain anything. It 372 00:21:28,080 --> 00:21:31,200 Speaker 1: just works. But is there anything like that in the 373 00:21:31,240 --> 00:21:35,200 Speaker 1: real world. Well it's not nearly so dramatic as that, 374 00:21:35,640 --> 00:21:38,840 Speaker 1: but the U see San Diego Jacob's School of Engineering 375 00:21:38,880 --> 00:21:41,560 Speaker 1: played host to a cool project that reminds me of 376 00:21:41,600 --> 00:21:45,480 Speaker 1: the invisibility cloak in Harry Potter. A research team published 377 00:21:45,480 --> 00:21:49,400 Speaker 1: a study in a journal called Progress in Electromagnetics Research 378 00:21:49,760 --> 00:21:54,199 Speaker 1: that detailed a cool technology they nicknamed a carpet cloak. 379 00:21:54,680 --> 00:21:57,840 Speaker 1: And with this tech, you could put an object on 380 00:21:57,880 --> 00:22:01,399 Speaker 1: a flat surface, like a table. You could then lay 381 00:22:01,440 --> 00:22:05,359 Speaker 1: the carpet cloak on top of this object. Now, a 382 00:22:05,400 --> 00:22:08,760 Speaker 1: normal piece of cloth would betray that something was in 383 00:22:08,800 --> 00:22:11,159 Speaker 1: fact underneath it. You would be able to see the 384 00:22:11,160 --> 00:22:15,120 Speaker 1: cloth bunched up and folded over the contours of the object. 385 00:22:15,520 --> 00:22:20,240 Speaker 1: But this new tech wouldn't appear to do that, assuming 386 00:22:20,280 --> 00:22:23,159 Speaker 1: you could see in the microwave range. According to the 387 00:22:23,200 --> 00:22:27,800 Speaker 1: senior author of the study, bubbacar Conte, the carpet would 388 00:22:27,840 --> 00:22:30,840 Speaker 1: create the illusion that it was laying flat on the 389 00:22:30,880 --> 00:22:34,320 Speaker 1: table as if nothing were under it at all, and 390 00:22:34,400 --> 00:22:39,520 Speaker 1: it used taflon and ceramics as dielectrics, a dielectric is 391 00:22:39,520 --> 00:22:43,760 Speaker 1: a material that acts as a poor conductor or an insulator. 392 00:22:43,800 --> 00:22:47,920 Speaker 1: When you subject a dielectric to an electric field, very 393 00:22:47,920 --> 00:22:51,600 Speaker 1: little current will flow in the material because there's no 394 00:22:51,760 --> 00:22:56,440 Speaker 1: free electrons in the material to have current flowing. However, 395 00:22:56,760 --> 00:23:01,280 Speaker 1: the material does become electrically polarized. The positive charges of 396 00:23:01,320 --> 00:23:04,840 Speaker 1: the of the dielectric are attracted to the electric field 397 00:23:05,119 --> 00:23:08,520 Speaker 1: and the negative charges in the dielectric are repulsed by it, 398 00:23:08,800 --> 00:23:13,080 Speaker 1: and this separation of charge it's minute, but it reduces 399 00:23:13,119 --> 00:23:17,359 Speaker 1: the electric field within the dielectric anyway. The combination of 400 00:23:17,400 --> 00:23:22,159 Speaker 1: teflon and ceramics scatter the microwaves to mimic a reflection 401 00:23:22,240 --> 00:23:25,639 Speaker 1: pattern of a flat surface. So while there are actual 402 00:23:25,720 --> 00:23:30,639 Speaker 1: deformations in this carpet cloak, the way the material scatters 403 00:23:30,680 --> 00:23:34,320 Speaker 1: electromagnetic radiation makes it appear as if it is flat. 404 00:23:34,560 --> 00:23:37,480 Speaker 1: So in reality it is folded around an object, but 405 00:23:37,800 --> 00:23:41,320 Speaker 1: from a microwave perspective, it's as if it's a perfectly 406 00:23:41,440 --> 00:23:43,920 Speaker 1: flat piece of cloth. If you were to reach out 407 00:23:43,960 --> 00:23:46,080 Speaker 1: and touch the material, you would actually feel the spots 408 00:23:46,080 --> 00:23:49,360 Speaker 1: where it covered the object. But again, this was entirely 409 00:23:49,480 --> 00:23:53,360 Speaker 1: on the microwave scale, not visible light, so to our 410 00:23:53,440 --> 00:23:58,040 Speaker 1: eyes everything would seem exactly the same. Microwaves have a 411 00:23:58,080 --> 00:24:01,440 Speaker 1: wavelength of about ten to the minus two meters, meaning 412 00:24:01,480 --> 00:24:05,480 Speaker 1: they are on the centimeter scale, but visible light has 413 00:24:05,520 --> 00:24:09,080 Speaker 1: wavelengths closer to point five times ten to the minus 414 00:24:09,119 --> 00:24:12,680 Speaker 1: six meters. I mean, they have a much smaller wavelength 415 00:24:12,720 --> 00:24:16,880 Speaker 1: and therefore a higher frequency. Designing material that can scatter 416 00:24:17,040 --> 00:24:21,320 Speaker 1: visible light requires more precision than something for microwaves. The 417 00:24:21,480 --> 00:24:24,560 Speaker 1: cloak carpet falls into a general category of stuff we 418 00:24:24,640 --> 00:24:28,680 Speaker 1: call meta materials, and those are super cool. So let's 419 00:24:28,720 --> 00:24:31,600 Speaker 1: talk about what they are and how they work right 420 00:24:31,640 --> 00:24:41,760 Speaker 1: after we take this break to thank our sponsor. So 421 00:24:41,840 --> 00:24:45,240 Speaker 1: what is a meta material? Well, they're different kinds, but 422 00:24:45,520 --> 00:24:49,600 Speaker 1: two of the defining features are that one this is 423 00:24:49,600 --> 00:24:52,680 Speaker 1: stuff that's made by humans, so you do not find 424 00:24:52,760 --> 00:24:56,840 Speaker 1: meta materials in nature, and two, they tend to have 425 00:24:56,920 --> 00:25:01,399 Speaker 1: properties that are either uncommon or un heard of in nature. 426 00:25:01,800 --> 00:25:05,040 Speaker 1: So it's stuff we make what acts differently than stuff 427 00:25:05,080 --> 00:25:08,679 Speaker 1: we encounter in the natural world. Menty materials get their 428 00:25:08,760 --> 00:25:13,359 Speaker 1: unique properties not just from the type of stuff they 429 00:25:13,359 --> 00:25:17,760 Speaker 1: are made from, but also their actual physical structure, which 430 00:25:17,800 --> 00:25:21,719 Speaker 1: makes them different from natural elements. So, for example, if 431 00:25:21,760 --> 00:25:24,040 Speaker 1: you were to go panning for gold and you found 432 00:25:24,119 --> 00:25:28,280 Speaker 1: a few gold nuggets, pure gold nuggets in a stream, 433 00:25:28,320 --> 00:25:31,800 Speaker 1: Those pure gold nuggets would have the same general properties 434 00:25:31,840 --> 00:25:35,520 Speaker 1: as say, a bar of pure gold or a piece 435 00:25:35,680 --> 00:25:38,560 Speaker 1: of pure gold jewelry. They would all be in different 436 00:25:38,600 --> 00:25:43,359 Speaker 1: shapes and sizes, but their properties would remain exactly the same. 437 00:25:43,400 --> 00:25:46,399 Speaker 1: It would still behave as gold, But a meta materials 438 00:25:46,400 --> 00:25:50,119 Speaker 1: properties depend at least partly on the structure of the 439 00:25:50,160 --> 00:25:54,680 Speaker 1: meta material itself. And by structure, i'm talking about repeated 440 00:25:54,720 --> 00:25:57,600 Speaker 1: patterns that are all the way down to the nano scale, 441 00:25:57,960 --> 00:26:01,879 Speaker 1: or maybe even further down to the atomic scale. A 442 00:26:01,960 --> 00:26:05,960 Speaker 1: nanometer is one billionth of a meter, and a human 443 00:26:06,000 --> 00:26:10,480 Speaker 1: hair can average about one hundred thousand nanometers in diameter. 444 00:26:10,640 --> 00:26:14,240 Speaker 1: So we are talking super small here, so small that 445 00:26:14,320 --> 00:26:17,679 Speaker 1: a light microscope will be of no help to you 446 00:26:17,840 --> 00:26:20,199 Speaker 1: if you want to look at this stuff, because the 447 00:26:20,359 --> 00:26:23,200 Speaker 1: light wavelengths are actually bigger than the things you're trying 448 00:26:23,240 --> 00:26:27,199 Speaker 1: to look at. To bend electromagnetic radiation, you have to 449 00:26:27,240 --> 00:26:32,040 Speaker 1: create these tiny, repeating patterns of structures inside this material. 450 00:26:32,800 --> 00:26:36,080 Speaker 1: What's more, the structures need to be at a scale 451 00:26:36,280 --> 00:26:41,440 Speaker 1: that's smaller than the length of the wavelength of electromagnetic 452 00:26:41,560 --> 00:26:44,520 Speaker 1: radiation that you plan to manipulate. Now, there are a 453 00:26:44,520 --> 00:26:49,400 Speaker 1: few ways that meta materials could manipulate electromagnetic radiation. One 454 00:26:49,440 --> 00:26:52,879 Speaker 1: way is to create what is called left handed material 455 00:26:53,160 --> 00:26:56,880 Speaker 1: and as a left hander, I really appreciate this. Left handedness. 456 00:26:56,880 --> 00:26:59,959 Speaker 1: When it comes to meto materials refers to two attributes, 457 00:27:00,480 --> 00:27:06,439 Speaker 1: permitivity and permeability. Permitivity refers to the resistance that is 458 00:27:06,560 --> 00:27:12,200 Speaker 1: encountered when an electric field interacts with this material. Permeability 459 00:27:12,240 --> 00:27:16,320 Speaker 1: refers to the degree of magnetization within a material that's 460 00:27:16,359 --> 00:27:20,840 Speaker 1: interacting with a magnetic field. If both the permitivity and 461 00:27:21,040 --> 00:27:25,280 Speaker 1: the permeability of a substance is negative, that substance is 462 00:27:25,320 --> 00:27:28,080 Speaker 1: said to be left handed. Now, you can also have 463 00:27:28,359 --> 00:27:32,800 Speaker 1: single negative meta materials, in which either the permitivity or 464 00:27:32,880 --> 00:27:37,639 Speaker 1: the permeability is negative, but not both. Most stuff in nature, however, 465 00:27:37,720 --> 00:27:43,040 Speaker 1: falls into double positive category, meaning both permitivity and permeability 466 00:27:43,160 --> 00:27:47,760 Speaker 1: is positive. So meta materials fly in the face of nature. 467 00:27:48,240 --> 00:27:52,560 Speaker 1: Take that, nature, I think you're so big. The carpet 468 00:27:52,600 --> 00:27:55,240 Speaker 1: cloak is an example of meta materials that have the 469 00:27:55,280 --> 00:27:59,840 Speaker 1: capability of bending microwaves around them as if the material 470 00:28:00,080 --> 00:28:03,280 Speaker 1: wasn't there. Though, as I mentioned earlier, right now scientists 471 00:28:03,320 --> 00:28:06,800 Speaker 1: are working on wavelengths that are in that centimeter range 472 00:28:07,119 --> 00:28:11,280 Speaker 1: or maybe as small as near infrared, which is still 473 00:28:11,320 --> 00:28:14,040 Speaker 1: a much larger wavelength than visible light. They have not 474 00:28:14,119 --> 00:28:17,520 Speaker 1: managed anything that would work in the visible range. In 475 00:28:17,640 --> 00:28:19,560 Speaker 1: order to do that, they would have to build these 476 00:28:19,560 --> 00:28:22,800 Speaker 1: repeated structured patterns at a very tiny scale. We're talking 477 00:28:22,840 --> 00:28:27,760 Speaker 1: like ten to twenty nanometers max. Developing that technique will 478 00:28:27,760 --> 00:28:30,480 Speaker 1: be a challenge, and making enough of it to say 479 00:28:30,600 --> 00:28:33,960 Speaker 1: code a jet might be outside the realm of possibility, 480 00:28:34,400 --> 00:28:38,200 Speaker 1: And that phrase visible range is also important. It might 481 00:28:38,240 --> 00:28:42,200 Speaker 1: be really tricky or maybe even impossible to design a 482 00:28:42,200 --> 00:28:46,400 Speaker 1: meta material that can work across the entire visible spectrum 483 00:28:46,480 --> 00:28:49,680 Speaker 1: of light wavelengths. We might be able to create materials 484 00:28:49,680 --> 00:28:51,960 Speaker 1: that allow certain types of light to bend around it 485 00:28:52,320 --> 00:28:55,400 Speaker 1: while it still reflects other wavelengths. Such a material might, 486 00:28:55,560 --> 00:28:59,080 Speaker 1: let's say, let red light pass right through it, but 487 00:28:59,200 --> 00:29:01,920 Speaker 1: reflect all of the wavelengths of light. Now, that would 488 00:29:01,920 --> 00:29:03,480 Speaker 1: be a pretty cool way to create a gel for 489 00:29:03,520 --> 00:29:06,800 Speaker 1: a theater light I imagine, But it doesn't turn something 490 00:29:06,840 --> 00:29:09,320 Speaker 1: completely invisible. It just means that you would have no 491 00:29:09,520 --> 00:29:13,320 Speaker 1: red reflected back from that particular object. All the stuff 492 00:29:13,320 --> 00:29:15,520 Speaker 1: you would see would not have any red in it, 493 00:29:15,640 --> 00:29:17,520 Speaker 1: and all the red light would go on to the 494 00:29:17,520 --> 00:29:20,960 Speaker 1: other side. In a similar vein, you wouldn't be able 495 00:29:20,960 --> 00:29:25,760 Speaker 1: to manipulate all wavelengths of electromagnetic radiation with a basic 496 00:29:25,840 --> 00:29:29,480 Speaker 1: meta material. So while you could conceivably create a material 497 00:29:29,560 --> 00:29:32,400 Speaker 1: that could allow visible light to bend around it, other 498 00:29:32,440 --> 00:29:36,640 Speaker 1: types of electromagnetic radiation might remain unaffected, meaning you would 499 00:29:36,640 --> 00:29:39,400 Speaker 1: still be able to quote unquote see the object using 500 00:29:39,400 --> 00:29:42,240 Speaker 1: a different wavelength, like radar. So you might have an 501 00:29:42,280 --> 00:29:45,120 Speaker 1: invisible jet like Wonder Woman, but it will still show 502 00:29:45,200 --> 00:29:49,120 Speaker 1: up on people's sensors. Meta materials aren't necessarily restricted to 503 00:29:49,200 --> 00:29:54,080 Speaker 1: electromagnetic wave manipulation. However, there are scientists and engineers making 504 00:29:54,120 --> 00:29:57,280 Speaker 1: meta materials that will interact with other types of waves, 505 00:29:57,320 --> 00:30:02,000 Speaker 1: including physical waves like sound, owned waves, or waves in 506 00:30:02,000 --> 00:30:05,480 Speaker 1: the ocean. Imagine a material that can redirect sound waves 507 00:30:05,560 --> 00:30:09,680 Speaker 1: with incredible efficiency. You could design a space that amplifies 508 00:30:09,920 --> 00:30:13,200 Speaker 1: or nullifies sound. Or imagine a building made out of 509 00:30:13,240 --> 00:30:17,240 Speaker 1: meta materials that can redirect seismic waves so it's as 510 00:30:17,280 --> 00:30:20,560 Speaker 1: if these seismic waves just passed through the building. So 511 00:30:21,240 --> 00:30:24,440 Speaker 1: if an earthquake were shaking everything around the building, the 512 00:30:24,480 --> 00:30:27,240 Speaker 1: waves would actually move through the physical structure as if 513 00:30:27,240 --> 00:30:30,960 Speaker 1: nothing were there at all. And it could remain unaffected 514 00:30:31,040 --> 00:30:34,760 Speaker 1: by the earthquake. Much of the work and meta materials 515 00:30:34,880 --> 00:30:38,960 Speaker 1: does not have the goal of creating magically invisible matter. Rather, 516 00:30:39,120 --> 00:30:43,200 Speaker 1: it's to manipulate electromagnetic radiation to make technologies more effective. 517 00:30:43,280 --> 00:30:46,400 Speaker 1: For example, imagine solar cells that are made from materials 518 00:30:46,400 --> 00:30:49,640 Speaker 1: that capture light with greater efficiency, so we lose less 519 00:30:49,680 --> 00:30:52,720 Speaker 1: of the Sun's energy due to reflections off the solar cell. 520 00:30:53,360 --> 00:30:56,280 Speaker 1: Or imagine radio receivers that are more effective at picking 521 00:30:56,360 --> 00:30:59,800 Speaker 1: up week signals due to their physical structure or going 522 00:31:00,120 --> 00:31:03,280 Speaker 1: to the physical wave examples. Imagine a perfectly soundproofed room 523 00:31:03,480 --> 00:31:06,520 Speaker 1: that absorbs all sound from the outside, which I would 524 00:31:06,520 --> 00:31:09,080 Speaker 1: love to have so that every time someone walks in 525 00:31:09,240 --> 00:31:11,200 Speaker 1: or out of the door that's next to the studio, 526 00:31:11,520 --> 00:31:13,360 Speaker 1: it doesn't interrupt me and I don't have to say 527 00:31:13,400 --> 00:31:16,360 Speaker 1: things all over again. Maybe I have some personal stake 528 00:31:16,400 --> 00:31:19,479 Speaker 1: in this now. I recently read a report about a 529 00:31:19,480 --> 00:31:23,280 Speaker 1: team that made a meta material that's effective with sound waves, 530 00:31:23,400 --> 00:31:27,200 Speaker 1: and this research comes out of Pennsylvania State University. Researcher 531 00:31:27,320 --> 00:31:31,320 Speaker 1: Amanda D. Hanford used meta materials to bend sound waves 532 00:31:31,360 --> 00:31:34,560 Speaker 1: around an object as if the object were not there, 533 00:31:34,920 --> 00:31:37,720 Speaker 1: and if you were to blast this object with sound waves, 534 00:31:37,960 --> 00:31:40,600 Speaker 1: the sound waves would continue onward as if there was 535 00:31:40,680 --> 00:31:43,000 Speaker 1: nothing in their way, so you wouldn't get any echoes 536 00:31:43,040 --> 00:31:47,440 Speaker 1: back from that object. And Hanford's meta material works under water. 537 00:31:48,120 --> 00:31:53,200 Speaker 1: That means such a material could shield an object from sonar. SONAR, 538 00:31:53,320 --> 00:31:57,160 Speaker 1: which was originally an acronym that stood for Sound Navigation 539 00:31:57,240 --> 00:32:01,400 Speaker 1: and ranging, uses sound as an echo location strategy. It's 540 00:32:01,480 --> 00:32:05,360 Speaker 1: essentially the sound equivalent to radar. Most radio waves do 541 00:32:05,440 --> 00:32:09,920 Speaker 1: not work so well underwater, but sonar is a different story. 542 00:32:09,720 --> 00:32:14,200 Speaker 1: Sound travels very well underwater, so for certain applications, such 543 00:32:14,240 --> 00:32:18,480 Speaker 1: as the navigation equipment aboard a submarine, sonar is incredibly useful. 544 00:32:18,760 --> 00:32:22,760 Speaker 1: But if you can shield objects from sonar, then there's 545 00:32:22,800 --> 00:32:25,240 Speaker 1: no way to know that there's an object there. A 546 00:32:25,320 --> 00:32:29,800 Speaker 1: submarine's sonar equipment wouldn't detect this object, potentially resulting in 547 00:32:29,800 --> 00:32:33,760 Speaker 1: a crash. Or you could conceivably use meta materials to 548 00:32:33,880 --> 00:32:38,600 Speaker 1: hide a full submarine, creating a Red October sort of situation, 549 00:32:38,640 --> 00:32:41,400 Speaker 1: which is pretty cool. Now, when we ever have a 550 00:32:41,400 --> 00:32:44,840 Speaker 1: cloaking device like the ones in science fiction films, I'm 551 00:32:44,840 --> 00:32:48,040 Speaker 1: not gonna say it will never happen. Science and technology 552 00:32:48,080 --> 00:32:51,280 Speaker 1: can do amazing things, and it may be that we 553 00:32:51,320 --> 00:32:53,920 Speaker 1: solve this challenge using those tools, but it's going to 554 00:32:54,000 --> 00:32:57,520 Speaker 1: take some time if it is possible. In the meantime, 555 00:32:57,720 --> 00:33:00,920 Speaker 1: will probably see some really amazing applications of these various 556 00:33:00,960 --> 00:33:04,080 Speaker 1: strategies for stuff that is just as cool as turning 557 00:33:04,120 --> 00:33:06,960 Speaker 1: a cling on bird of prey invisible. And that wraps 558 00:33:07,040 --> 00:33:09,840 Speaker 1: up this discussion about cloaking devices. I hope you enjoyed it. 559 00:33:09,880 --> 00:33:12,959 Speaker 1: If you have any suggestions for future episodes of tech Stuff, 560 00:33:13,360 --> 00:33:16,160 Speaker 1: right me. My email address is tech Stuff at how 561 00:33:16,200 --> 00:33:18,800 Speaker 1: stuff works dot com, or drop me a line on 562 00:33:18,800 --> 00:33:21,040 Speaker 1: Facebook or Twitter, or the handle at both of those 563 00:33:21,080 --> 00:33:24,480 Speaker 1: locations is text stuff hs W. Don't forget. We have 564 00:33:24,520 --> 00:33:27,320 Speaker 1: an Instagram account and you should be following. And I 565 00:33:27,600 --> 00:33:31,320 Speaker 1: broadcast live every Wednesday and Friday over at twitch dot 566 00:33:31,360 --> 00:33:33,520 Speaker 1: tv slash tech Stuff. 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