WEBVTT - Engage the Cloaking Device 0:00:04.160 --> 0:00:07.200 Get in tech with technology with tech Stuff from half 0:00:07.240 --> 0:00:13.600 stuff works dot com. Hey there, and welcome to tech Stuff. 0:00:13.680 --> 0:00:16.960 I'm your host, Jonathan Strickland. I'm an executive producer here 0:00:17.000 --> 0:00:19.840 at how Stuff Works in a love all things tech. 0:00:19.880 --> 0:00:23.159 And not only do I love all things tech, I 0:00:23.320 --> 0:00:27.680 also love science fiction. Those who have listened to the 0:00:27.680 --> 0:00:29.680 show for a while know that I have a deep 0:00:29.720 --> 0:00:32.479 love of science fiction, and no small part due to 0:00:32.479 --> 0:00:35.520 my parents, who are both science fiction fans and authors. 0:00:36.159 --> 0:00:39.199 And one of my favorite gadgets in science fiction is 0:00:39.280 --> 0:00:43.199 the cloaking device. Now, the earliest example I can remember 0:00:43.520 --> 0:00:47.839 from my own personal experience is from Star Trek, because 0:00:47.920 --> 0:00:51.279 the Klingons and the Romulans in Star Trek had access 0:00:51.320 --> 0:00:55.680 to technology that could render their ships not just undetectable 0:00:55.720 --> 0:01:02.120 by sensors, but completely invisible. So this goes beyond stealth technology, 0:01:02.160 --> 0:01:06.160 which uses materials and architecture to confound devices like radar. 0:01:06.200 --> 0:01:08.920 I'll talk more about that later, but this would be 0:01:08.959 --> 0:01:13.720 a technology that could turn an entire spacecraft completely invisible, 0:01:13.840 --> 0:01:18.080 allowing light and other electromagnetic energy to bend around it 0:01:18.160 --> 0:01:22.320 in such a way as to seemingly pass through it entirely, 0:01:22.760 --> 0:01:25.440 so you can think kind of like light in this sense, 0:01:25.480 --> 0:01:30.000 being like flowing water. Imagine a stream of water flowing downhill, 0:01:30.480 --> 0:01:34.000 and you place a rock in the middle of that stream, 0:01:34.040 --> 0:01:36.759 and the water will part around that rock and come 0:01:36.800 --> 0:01:39.160 back together on the other side. And so if you're 0:01:39.160 --> 0:01:41.640 just a little further downstream, you would never know there 0:01:41.680 --> 0:01:43.640 was a rock there in the first place, because the 0:01:43.640 --> 0:01:45.760 way the water is flowing, it looks like it's been 0:01:45.800 --> 0:01:48.600 moving in a straight line the whole time. That's simply 0:01:49.000 --> 0:01:52.400 the same kind of concept for cloaking devices, except instead 0:01:52.400 --> 0:01:58.320 of water, we're talking about electromagnetic radiation. That's the basic premise, right, 0:01:58.720 --> 0:02:01.880 It somehow is able to bend energy so that it 0:02:01.920 --> 0:02:05.760 flows around the object and continues on its original trajectory 0:02:05.880 --> 0:02:08.240 as if nothing were there to begin with. To an 0:02:08.240 --> 0:02:11.400 outside observer relying upon this type of energy to quote 0:02:11.440 --> 0:02:14.760 unquote see the cloaked object, it would seem as if 0:02:14.800 --> 0:02:17.800 nothing were there at all. When it comes to science fiction, 0:02:18.160 --> 0:02:22.600 writers tend to rely upon terms that sound vaguely futuristic 0:02:22.600 --> 0:02:27.200 and scientific, but typically they don't actually mean anything. Most 0:02:27.240 --> 0:02:31.040 of them rely on fictional energies or materials, but there 0:02:31.080 --> 0:02:34.720 are real world examples of cloaking devices that I would 0:02:34.720 --> 0:02:37.520 like to talk about. Before I jump into that, I 0:02:37.560 --> 0:02:41.440 need to make one thing very clear. The cloaking devices 0:02:41.600 --> 0:02:45.840 and technologies I'll be covering will not turn objects invisible 0:02:45.880 --> 0:02:48.240 to the naked eye. They don't work at that end 0:02:48.280 --> 0:02:51.280 of the electromagnetic spectrum, at least not the ones that 0:02:51.320 --> 0:02:53.680 are on the higher tech end of it. Some of 0:02:53.680 --> 0:02:57.080 them use optical illusions to make it seem that way. 0:02:57.120 --> 0:03:01.000 This little fact, however, sometimes gets lost in reporting of 0:03:01.120 --> 0:03:04.639 cloaking technology. The headlines are too good to say new 0:03:04.680 --> 0:03:08.960 cloaking device makes it a reality, or sometimes the information 0:03:09.080 --> 0:03:11.959 is included in the reporting and then everyone gets a 0:03:11.960 --> 0:03:14.120 little bummed out about it because it's not a quote 0:03:14.160 --> 0:03:18.280 unquote real cloaking device. I'll also cover a few technologies 0:03:18.320 --> 0:03:22.280 that create this illusion of a cloaking device under specific criteria, 0:03:22.360 --> 0:03:25.040 because the solution is actually a kind of clever and 0:03:25.160 --> 0:03:29.280 a good place to start is with stealth technology. Now 0:03:29.320 --> 0:03:32.840 I've covered stealth tech in a previous episode of Tech Stuff, 0:03:33.120 --> 0:03:35.960 but I'm gonna go and cover some of it again 0:03:36.080 --> 0:03:38.360 right here. I'm just gonna go really light on history, 0:03:38.440 --> 0:03:40.480 because you can listen to the other episode and get 0:03:40.520 --> 0:03:43.040 the full story. I just want to talk about how 0:03:43.120 --> 0:03:47.760 stealth fighters and stealth bombers work from that stealth perspective. First, 0:03:48.360 --> 0:03:50.680 I'm sure you've seen pictures of these sorts of vehicles 0:03:50.720 --> 0:03:52.720 and you might notice right away that they don't appear 0:03:52.760 --> 0:03:55.600 to be invisible. You can kind of sort of totally 0:03:55.640 --> 0:04:00.960 see them. One makes them stealth isn't there ability to 0:04:01.160 --> 0:04:03.480 disappear in front of your very eyes, because they don't 0:04:03.600 --> 0:04:09.000 have that, but rather their ability to evade detection via radar. Now, 0:04:09.120 --> 0:04:15.480 radar works like echolocation. Electromagnetic symbol signals rather beam out 0:04:15.760 --> 0:04:19.480 from a transmitter, and then those signals collide with an 0:04:19.480 --> 0:04:23.040 object like a jet. Some of those signals bounce off 0:04:23.080 --> 0:04:26.400 the jet and bounce back towards the transmitter. You also, 0:04:26.520 --> 0:04:29.760 besides the transmitter, have a receiver, and the receiver picks 0:04:29.880 --> 0:04:34.520 up these returning signals and registers that there's an aircraft 0:04:34.720 --> 0:04:38.680 present in the airspace. If there's a change in wavelength 0:04:38.960 --> 0:04:41.599 the radio In the radio signals, you can also deduce 0:04:41.640 --> 0:04:44.480 if the aircraft is moving toward you or away from you. 0:04:45.000 --> 0:04:48.320 If the radio waves are longer than they were when 0:04:48.360 --> 0:04:51.160 you blasted them out, that means the objects moving away. 0:04:51.400 --> 0:04:54.760 If they're elongated. In other words, if the wavelengths are 0:04:54.839 --> 0:04:59.120 shorter the object is coming toward you. This is the 0:04:59.200 --> 0:05:01.840 Doppler of act. It's the same sort of thing you 0:05:01.920 --> 0:05:06.440 might experience if a car with a siren blasting drives 0:05:06.480 --> 0:05:09.359 past you. It sounds higher pitched as the car is 0:05:09.400 --> 0:05:12.040 coming towards you, and lower pitched as the car is 0:05:12.120 --> 0:05:14.360 moving away from you. And that's because the sound waves 0:05:14.360 --> 0:05:18.120 themselves are being compressed in front of the vehicle as 0:05:18.160 --> 0:05:21.400 it moves towards you, and they're elongated as the vehicle 0:05:21.480 --> 0:05:24.159 moves away from you. Same sort of thing can happen 0:05:24.160 --> 0:05:27.000 with electromagnetic waves, and like I said, it's called the 0:05:27.000 --> 0:05:30.400 Doppler effect. Also, by looking at the delay between when 0:05:30.440 --> 0:05:34.480 the radio waves blasted out from the transmitter and when 0:05:34.560 --> 0:05:37.600 the returning waves were picked up by the receiver, you 0:05:37.640 --> 0:05:40.480 know how far away the aircraft is because the radio 0:05:40.520 --> 0:05:44.760 waves travel at a constant speed. So by knowing how 0:05:44.800 --> 0:05:49.560 much time has passed, you know how how far away 0:05:49.800 --> 0:05:52.359 the aircraft is. Right, you just measure the amount of 0:05:52.360 --> 0:05:54.480 time that has passed and then you do a quick 0:05:54.520 --> 0:05:58.000 calculation to say, well, it traveled x distance in this 0:05:58.040 --> 0:06:01.000 amount of time. Let's take half of that at because 0:06:01.040 --> 0:06:04.320 the signals traveled out and then they traveled back, so 0:06:04.480 --> 0:06:07.479 half of the full length of travel time is how 0:06:07.520 --> 0:06:11.880 far away the aircraft is, roughly speaking, So stealth technology 0:06:12.080 --> 0:06:17.240 is all about foiling that process. The two major methods 0:06:17.720 --> 0:06:21.880 involved creating a radar absorbent surface, something that is very 0:06:21.920 --> 0:06:27.120 efficient at absorbing electromagnetic radiation, and then making sure that 0:06:27.200 --> 0:06:31.680 the aircraft has a particular shape to reflect any other 0:06:31.800 --> 0:06:36.400 radio waves in different directions than the origin source. The 0:06:36.480 --> 0:06:39.680 absorbent surface is a composite material that's made of lots 0:06:39.680 --> 0:06:43.920 of different lightweight stuff that's really efficient at absorbing radio energy. 0:06:43.960 --> 0:06:46.839 If the aircraft absorbs the radio waves from a radio antenna, 0:06:47.279 --> 0:06:50.120 nothing would bounce back and nothing would get picked up 0:06:50.160 --> 0:06:53.360 by the receiver. So if you had a perfect absorbent material, 0:06:54.040 --> 0:06:56.960 it would just soak in all those radio waves. Nothing 0:06:57.000 --> 0:06:59.960 would ever return, so it would never show up on radar. 0:07:00.240 --> 0:07:03.320 But we don't have anything that's quite that perfect. The 0:07:03.400 --> 0:07:06.120 plane's shape plays a really big part in this as well, 0:07:06.600 --> 0:07:09.040 because a radio wave will bounce off of surfaces and 0:07:09.080 --> 0:07:11.720 return at an angle, just as if you were to bounce, 0:07:11.720 --> 0:07:14.840 say a cue ball inside a pool table. You know, 0:07:14.920 --> 0:07:18.280 if you choose different angles. When you're bouncing the cue ball, 0:07:18.520 --> 0:07:20.320 it's going to react in a different way. It's going 0:07:20.360 --> 0:07:23.800 to bounce off in a different direction. Um And once 0:07:23.840 --> 0:07:26.720 you know that relationship, then you can start to design 0:07:26.800 --> 0:07:30.920 surfaces to bounce those radio waves off in directions that 0:07:30.960 --> 0:07:33.880 are not going to go back toward the receiver. The 0:07:33.880 --> 0:07:36.240 shape of stealth vehicles tends to include a lot of 0:07:36.440 --> 0:07:40.800 curved surfaces that seemingly wonky angles. Sometimes you'll get some 0:07:40.920 --> 0:07:44.520 very flat surfaces as well, but they'll be in odd 0:07:45.280 --> 0:07:47.840 positions relative to one another. And this is all to 0:07:47.920 --> 0:07:51.360 try and foil those radio waves, to make them bounce 0:07:51.400 --> 0:07:54.080 in a way that's not going to go back to 0:07:54.120 --> 0:07:58.160 where the receiver is. So the electromagnetic radiation does not 0:07:58.600 --> 0:08:02.520 pass through the air craft, it doesn't bend around it 0:08:02.600 --> 0:08:04.720 the way you would say a cloaking device would do, 0:08:05.280 --> 0:08:08.720 but it does allow you to have a way of 0:08:08.800 --> 0:08:12.440 eluding radar detection. So it's not really the same sort 0:08:12.480 --> 0:08:15.800 of technology that you would find in science fiction. Now, 0:08:15.800 --> 0:08:19.280 there are other ways you can simulate a cloaking device, 0:08:19.480 --> 0:08:21.600 such as a method that has been used in several 0:08:21.640 --> 0:08:24.680 marketing campaigns, and that as to use a series of 0:08:24.760 --> 0:08:29.760 cameras and screens to simulate a cloaking device. The concept 0:08:29.880 --> 0:08:33.080 is pretty simple. You start with an object. Let's say 0:08:33.160 --> 0:08:37.720 it's a Mercedes Benz F Cell concept vehicle, because Mercedes 0:08:37.760 --> 0:08:40.960 actually did do this as a marketing stunt back in 0:08:41.040 --> 0:08:43.760 two thousand twelve. The F Cell, by the way, was 0:08:43.920 --> 0:08:47.280 a fuel cell prototype vehicle, and I've talked all about 0:08:47.280 --> 0:08:51.760 fuel cells in other episodes. Pretty fascinating technology anyway. Imagine 0:08:51.800 --> 0:08:54.960 that you cover one full side of this vehicle, let's 0:08:54.960 --> 0:08:58.800 say the driver's side of the vehicle, with a mesh 0:08:58.920 --> 0:09:00.880 that has a bunch of l e d s in 0:09:00.960 --> 0:09:04.640 it to act as a screen, so the side of 0:09:04.640 --> 0:09:07.680 the car turns into a low resolution l e ED 0:09:07.880 --> 0:09:10.840 television screen. On the other side of the vehicle, you 0:09:10.920 --> 0:09:14.160 mount a camera and the camera captures everything that's on 0:09:14.320 --> 0:09:16.480 that side of the vehicle. So it's facing out from 0:09:16.480 --> 0:09:19.400 the passenger side, so it would be the same kind 0:09:19.400 --> 0:09:21.760 of point of view as a passenger would have if 0:09:21.800 --> 0:09:24.880 he or she was looking directly out of their window. 0:09:25.960 --> 0:09:30.000 The video feed you pick up from this camera gets 0:09:30.040 --> 0:09:33.439 fed directly to the other side, to the l e 0:09:33.559 --> 0:09:38.439 ED screen side of the vehicle, and it displays whatever 0:09:38.480 --> 0:09:42.760 the cameras have picked up, so you end up getting 0:09:43.200 --> 0:09:46.120 this illusion. If you stand on the screen side of 0:09:46.120 --> 0:09:49.800 the vehicle, it's almost like you're looking through it, though 0:09:49.800 --> 0:09:52.400 at a lower resolution than reality, so it looks a 0:09:52.440 --> 0:09:55.160 little jankie. Although you could argue that's kind of like 0:09:55.200 --> 0:09:58.040 a cloaking effect you see in some science fiction shows 0:09:58.080 --> 0:10:01.280 and movies where you've got that little shimmery effect. It's 0:10:01.360 --> 0:10:03.640 kind of like that, but less cool than that. Not 0:10:03.760 --> 0:10:08.040 so predator. It's a little more uh noticeable. I've seen 0:10:08.080 --> 0:10:10.800 similar setups to make an effect in costumes that make 0:10:10.840 --> 0:10:14.000 it look like a person has a hole straight through 0:10:14.040 --> 0:10:16.760 their torso. It's a pretty cool thing to do. It's 0:10:16.760 --> 0:10:20.160 actually really easy if you've got two iPads. For example, 0:10:20.720 --> 0:10:23.600 Uh they typically will wear a screen on their chest, 0:10:24.360 --> 0:10:26.720 and then you can put a camera on your back 0:10:27.360 --> 0:10:31.520 and the camera captures live video from whatever is going 0:10:31.559 --> 0:10:36.000 on behind you, feeds it to the screen that's hanging 0:10:36.040 --> 0:10:39.000 on front of your torso, and you cut a hole 0:10:39.040 --> 0:10:42.720 in a shirt so that it it goes right around 0:10:42.720 --> 0:10:45.600 the screen and the screen is showing everything that's happening 0:10:45.600 --> 0:10:47.680 behind you. So the illusion is that you've got a 0:10:47.720 --> 0:10:50.400 hole in your torso and people can look right through 0:10:50.440 --> 0:10:53.360 it and see what's happening on the other side. Uh. 0:10:53.480 --> 0:10:55.120 Like I said, you could actually do this in a 0:10:55.120 --> 0:10:58.320 pretty easy way. I saw a clever video that used 0:10:58.360 --> 0:11:01.160 a pair of iPad two tablet to make this effect 0:11:01.240 --> 0:11:04.480 on both sides. The guy who published the video's name 0:11:04.520 --> 0:11:07.200 is Mark Rober. He published the video on YouTube in 0:11:07.240 --> 0:11:10.040 October two thousand eleven, so you can actually find this 0:11:10.160 --> 0:11:11.800 video if you want to see how he did it. 0:11:12.280 --> 0:11:15.240 But he said he used two iPad two's, one to 0:11:15.280 --> 0:11:18.839 face out in front and one to face out in back. 0:11:19.400 --> 0:11:22.520 So the but the screens were facing outward on both sides. 0:11:22.559 --> 0:11:24.560 One facing one had you know, the back of the 0:11:24.559 --> 0:11:27.240 iPad two was against his chest. The other one had 0:11:27.280 --> 0:11:29.520 the back of the second iPad two against his back. 0:11:30.240 --> 0:11:31.920 And what he did was he just set up a 0:11:31.920 --> 0:11:36.080 FaceTime call between the two iPads, so each iPad was 0:11:36.120 --> 0:11:40.280 showing the screen of the other iPads camera and by 0:11:40.320 --> 0:11:43.720 doing that, you just have this live feed on either side. 0:11:43.800 --> 0:11:46.160 So it worked on either side of the person. You 0:11:46.160 --> 0:11:48.640 could stand in front of them and you're actually looking 0:11:49.000 --> 0:11:51.480 at the hole that's showing on showing what's going on 0:11:51.520 --> 0:11:53.920 behind the person, or you could be behind them, and 0:11:53.920 --> 0:11:55.880 you'd be looking through the hole and you see what's 0:11:55.920 --> 0:11:57.840 going on in front of that person, so you get 0:11:57.840 --> 0:12:00.880 this illusion that you have a hole going through a 0:12:00.920 --> 0:12:03.400 solid Torso it's great if you want to do a 0:12:03.440 --> 0:12:08.959 creepy zombie style character at Halloween. I've always wanted to 0:12:09.000 --> 0:12:11.400 do this, but I've never actually gone out to buy 0:12:11.400 --> 0:12:14.600 a couple of iPads just to do a costume. It 0:12:14.600 --> 0:12:16.360 seems like it might be a little much for me, 0:12:16.440 --> 0:12:20.040 but still pretty neat. However, again, that's not a true 0:12:20.040 --> 0:12:22.560 cloaking device. I don't think anyone would ever argue that. 0:12:22.720 --> 0:12:26.120 And for one thing, any set up where you've got 0:12:26.160 --> 0:12:29.679 a screen and a camera means that you really only 0:12:29.720 --> 0:12:34.920 have one side prepared to be quote unquote cloaked. So 0:12:35.000 --> 0:12:38.240 if you're on the other side of the device or 0:12:38.280 --> 0:12:41.120 the structure or whatever it is, you would totally see 0:12:41.559 --> 0:12:45.480 the object or the person standing there because you would 0:12:45.520 --> 0:12:49.559 be on the camera side, not the screen side. It's 0:12:49.600 --> 0:12:52.160 kind of like being backstage in a show. You see 0:12:52.160 --> 0:12:57.000 how everything works, so it's not truly cloaking. But next, 0:12:57.440 --> 0:13:00.839 we're gonna talk about bending light and something you can 0:13:00.880 --> 0:13:05.400 actually do. We can bend light optical lenses do that, 0:13:05.760 --> 0:13:09.200 so if you wear glasses or contacts, you rely on 0:13:09.360 --> 0:13:12.880 something that bends light already, and I talked about the 0:13:12.880 --> 0:13:16.280 physics of optical lenses in an episode not too far back. 0:13:16.320 --> 0:13:19.679 But if you're clever and you use the right sequence 0:13:19.840 --> 0:13:23.200 of lenses at the proper distance from one another, you 0:13:23.200 --> 0:13:26.880 can create an optical illusion equal to a type of cloaking. 0:13:27.360 --> 0:13:31.079 And that's the secret behind the original Rochester Cloak, so 0:13:31.120 --> 0:13:34.160 called because it was developed at the University of Rochester. 0:13:34.760 --> 0:13:37.440 Now I'll talk more about their approach to cloaking in 0:13:37.480 --> 0:13:40.600 just a second, but first let's take a quick break 0:13:40.760 --> 0:13:50.839 to thank our sponsor. The version of the Rochester Cloak 0:13:50.960 --> 0:13:54.839 I studied had four lenses arranged in a straight line 0:13:55.040 --> 0:13:58.760 with several inches separating each lens. So think of it 0:13:58.800 --> 0:14:02.840 as lens one, two, three, four, And let's say that 0:14:02.880 --> 0:14:06.480 for the purposes of this description, that the lens closest 0:14:06.640 --> 0:14:09.839 to someone who's going to look through the Rochester Cloak 0:14:10.520 --> 0:14:14.079 is lens number one. The furthest lens from the viewer 0:14:14.360 --> 0:14:17.400 is lens number four. Now, in the demonstration I viewed 0:14:18.200 --> 0:14:24.120 the uh the the backdrop for this was a grid pattern, 0:14:24.320 --> 0:14:27.120 So there was actually a grid pattern in the very back, 0:14:27.880 --> 0:14:31.040 and the purpose of that was to provide a reference 0:14:31.240 --> 0:14:34.360 so that when you passed things between the lenses in 0:14:34.440 --> 0:14:37.160 order to create this cloaking effect, you would still see 0:14:37.160 --> 0:14:39.280 the grid pattern in the background, and it gives this 0:14:39.360 --> 0:14:43.080 illusion that you have an unbroken uh line of sight 0:14:43.200 --> 0:14:45.840 even when an object is passing between the lenses. So 0:14:46.280 --> 0:14:49.280 a casual glance through the lenses, it makes it seem 0:14:49.360 --> 0:14:52.040 like light has just passed through the series of lenses 0:14:52.040 --> 0:14:55.680 without bending. Like from from lens for two lens one, 0:14:56.080 --> 0:14:58.280 the effect you get is that the light has just 0:14:58.320 --> 0:15:01.640 traveled straight through those lenses, because the grids in the 0:15:01.680 --> 0:15:05.520 back remains straight, and that becomes your reference point. Right 0:15:05.520 --> 0:15:07.200 You're looking at the grids and you're thinking, well, the 0:15:07.240 --> 0:15:10.000 lines look straight, so the light's not really being bent 0:15:10.400 --> 0:15:13.680 by these lenses. At least that's the optical illusion I have. 0:15:15.240 --> 0:15:18.640 But what is really happening is some light gymnastics. And 0:15:18.800 --> 0:15:23.080 I don't mean low impact gymnastics. I mean gymnastics involving light. 0:15:23.640 --> 0:15:27.000 Each lens bends the light in a slightly different way, 0:15:27.520 --> 0:15:30.920 concentrating or spreading out the light, so that if you 0:15:30.960 --> 0:15:34.960 were to place a small object between Lens one and 0:15:35.120 --> 0:15:38.840 lens too, So the first two lenses it would look 0:15:38.880 --> 0:15:41.960 as if you could see right through the object with 0:15:42.280 --> 0:15:46.000 some limitations. The big limitation is that the cloaking effect 0:15:46.480 --> 0:15:49.840 only works on the edges of the viewing area of 0:15:49.880 --> 0:15:52.240 the lens. So if you think of the lens as 0:15:52.240 --> 0:15:55.000 a circle, the closer you get to the center of 0:15:55.040 --> 0:15:58.720 that circle, the closer you're getting to the point where 0:15:58.720 --> 0:16:00.880 you're going to be able to actually see that object. 0:16:00.880 --> 0:16:04.640 But if it's on the the edge of the center, 0:16:05.080 --> 0:16:08.320 then it seems like you can look right through the object. 0:16:09.080 --> 0:16:11.920 So uh, it's because the light is being bent in 0:16:11.920 --> 0:16:15.360 such a way that that light is concentrated on the 0:16:15.440 --> 0:16:19.800 center of lens number one before that lens actually spreads 0:16:19.800 --> 0:16:22.600 the light out again towards your eye. And each of 0:16:22.600 --> 0:16:26.160 these lenses was carefully selected so that it would manipulate 0:16:26.200 --> 0:16:30.320 the light where it seems like you're looking at an 0:16:30.400 --> 0:16:33.600 unaltered image. Right, it looks like you're looking at that 0:16:33.640 --> 0:16:36.600 grid and the lines are straight. In fact, the way 0:16:36.640 --> 0:16:39.640 that the light is being bent by the lens, if 0:16:39.680 --> 0:16:41.600 you were to look through lens number two instead of 0:16:41.640 --> 0:16:45.120 lens number one, the backdrop would look very different. It 0:16:45.160 --> 0:16:47.800 wouldn't look like a grid of straight lines. It's because 0:16:47.800 --> 0:16:51.080 each lens is bending light in a specific way that 0:16:51.160 --> 0:16:54.360 you're able to create this effect. So it doesn't matter 0:16:54.720 --> 0:16:57.120 if the object you put between lens one and lens 0:16:57.160 --> 0:17:01.000 two is a pencil or a finger, it seems like 0:17:01.040 --> 0:17:04.320 there is nothing there in front of you, or that 0:17:04.960 --> 0:17:07.720 the middle of the object has disappeared, like if you 0:17:07.760 --> 0:17:10.760 can see the object on either side of the lens, 0:17:10.800 --> 0:17:13.840 like if it extends out to either edge, it would 0:17:13.880 --> 0:17:16.520 look like the middle is just suddenly gone. But again, 0:17:16.560 --> 0:17:19.960 this is all just through optics, so it's somewhat limited 0:17:20.280 --> 0:17:23.840 as it's entirely dependent upon your frame of reference. It 0:17:24.200 --> 0:17:27.439 depends upon the viewer looking through the lens. If you 0:17:27.480 --> 0:17:29.439 were to step to the side and look at this 0:17:29.480 --> 0:17:33.320 apparatus from ninety degrees on, you would observe that there's 0:17:33.320 --> 0:17:36.160 no cloaking effect at all. The light your eyes would 0:17:36.160 --> 0:17:39.000 detect has not passed through that array of lenses, so 0:17:39.040 --> 0:17:41.760 all you would see is someone placing an object between 0:17:41.760 --> 0:17:44.199 two lenses, and it would not disappear. It would just 0:17:44.240 --> 0:17:47.560 be right there, so there'd be nothing special from your perspective. 0:17:47.960 --> 0:17:51.320 There are similar projects that use cameras, mirrors, and displays 0:17:51.680 --> 0:17:55.000 to create this type of illusion, but again they're dependent 0:17:55.080 --> 0:17:58.040 upon your frame of reference and perspective. If you step 0:17:58.040 --> 0:18:02.000 outside that frame of reference and truth settles in, then 0:18:02.040 --> 0:18:05.440 you notice that the thing is not really invisible or transparent. 0:18:05.520 --> 0:18:08.320 This is kind of like having a magician hide something 0:18:08.359 --> 0:18:11.760 behind a little curtain, and because you're looking at the curtain, 0:18:11.840 --> 0:18:13.919 you cannot see what's going on behind it. But if 0:18:13.960 --> 0:18:16.919 you were watching from the side of the magician, you 0:18:16.920 --> 0:18:18.919 can see how the trick was done, which is not 0:18:19.119 --> 0:18:21.920 much fun, but it does show that the optical illusion 0:18:21.960 --> 0:18:25.960 depends upon certain criteria to work, specifically where you are 0:18:26.040 --> 0:18:30.040 looking from. In two thousand seventeen, Toyota applied for a 0:18:30.080 --> 0:18:35.240 patent titled Apparatuses and Methods for making an Object Appear Transparent. 0:18:36.119 --> 0:18:38.359 So was this a way to turn an entire car 0:18:38.480 --> 0:18:43.119 invisible allah James Bond's Aston Martin v. Twelve Vanquished and 0:18:43.200 --> 0:18:47.600 Die Another Day. Not quite. This is a system meant 0:18:47.680 --> 0:18:51.760 to help the driver of the car. It's not meant 0:18:51.880 --> 0:18:56.359 for people outside the vehicle. Toyota's approach is a method 0:18:56.440 --> 0:19:00.119 to make certain features inside the car appear transparent to 0:19:00.160 --> 0:19:03.480 the driver, so that the driver can have an unimpeded 0:19:03.560 --> 0:19:07.440 view of the environment around the car. Specifically, the objects 0:19:07.440 --> 0:19:10.080 that were meant to be turned transparent were the A 0:19:10.320 --> 0:19:13.880 pillars inside the vehicle. Now, the pillars in a car 0:19:14.000 --> 0:19:18.240 are the supports of a car's window area, sometimes also 0:19:18.280 --> 0:19:22.720 called the greenhouse. Pillars are divided up as A, B, C, 0:19:23.160 --> 0:19:27.119 and if the vehicle's big enough, sometimes D pillars. The 0:19:27.280 --> 0:19:30.240 B pillars are sometimes called posts. Those are the ones 0:19:30.280 --> 0:19:32.960 that are on the side of the vehicle. Uh. The 0:19:33.040 --> 0:19:35.280 A pillars are the sections on either side of the 0:19:35.320 --> 0:19:38.080 windshield that support the windshield and connect to the top 0:19:38.119 --> 0:19:41.600 of the car in order to meet crash safety standards. 0:19:41.600 --> 0:19:44.480 Those pillars can be pretty wide to provide the necessary 0:19:44.480 --> 0:19:47.720 structural support, but that means they block some of your 0:19:47.800 --> 0:19:51.239 view while you're driving. So it's that section of a 0:19:51.280 --> 0:19:56.159 car that separates the front windshield from your side mirror 0:19:56.560 --> 0:20:00.439 or your side window. Rather so that that poe, that 0:20:00.600 --> 0:20:03.320 pillar is what Toyota was thinking about, like, how can 0:20:03.359 --> 0:20:06.080 we make it so that you can see through that 0:20:06.200 --> 0:20:10.440 pillar and thus have a better view out that side 0:20:10.440 --> 0:20:12.960 of your vehicle, so that you really don't have an 0:20:13.000 --> 0:20:16.600 impeded view from the front all the way over to 0:20:17.080 --> 0:20:20.320 your side window. How do you get rid of that 0:20:20.400 --> 0:20:23.760 gap from your vision. Well, according to the patent, Toyota's 0:20:23.880 --> 0:20:27.760 system redirects light using mirrors so that the light projects 0:20:27.840 --> 0:20:30.840 on the pillar itself, creating the illusion that the pillar 0:20:31.000 --> 0:20:34.879 is transparent and removing that gap from your visibility. And 0:20:34.920 --> 0:20:37.840 because it's a patent, anyone is free to look it 0:20:37.920 --> 0:20:41.320 over and read about the technology Toyota developed. So if 0:20:41.359 --> 0:20:42.640 you want to do it, if you want to read 0:20:42.680 --> 0:20:47.080 about some pretty complicated concepts and optics, I have the 0:20:47.160 --> 0:20:49.560 patent number for you. It is a long one, so 0:20:49.640 --> 0:20:54.680 get ready. The patent application number is US two thousand, 0:20:54.800 --> 0:21:01.360 seventeen zero two two seven seven eight one a one. 0:21:01.640 --> 0:21:04.200 So if you put that into a patent search, you're 0:21:04.200 --> 0:21:06.000 gonna pull this up and you can read all about 0:21:06.080 --> 0:21:11.359 how Toyota proposes this technology be implemented. But what about 0:21:11.359 --> 0:21:13.919 a cloak more in line with the invisibility cloak in 0:21:13.920 --> 0:21:17.640 Harry Potter. In J. K. Rowling's books, characters make use 0:21:17.760 --> 0:21:21.320 of the invisibility cloak to snoop in on important exposition. 0:21:21.880 --> 0:21:24.960 And in that world it all works via magic, which 0:21:25.000 --> 0:21:27.919 is great because there's no need to explain anything. It 0:21:28.080 --> 0:21:31.200 just works. But is there anything like that in the 0:21:31.240 --> 0:21:35.200 real world. Well it's not nearly so dramatic as that, 0:21:35.640 --> 0:21:38.840 but the U see San Diego Jacob's School of Engineering 0:21:38.880 --> 0:21:41.560 played host to a cool project that reminds me of 0:21:41.600 --> 0:21:45.480 the invisibility cloak in Harry Potter. A research team published 0:21:45.480 --> 0:21:49.400 a study in a journal called Progress in Electromagnetics Research 0:21:49.760 --> 0:21:54.199 that detailed a cool technology they nicknamed a carpet cloak. 0:21:54.680 --> 0:21:57.840 And with this tech, you could put an object on 0:21:57.880 --> 0:22:01.399 a flat surface, like a table. You could then lay 0:22:01.440 --> 0:22:05.359 the carpet cloak on top of this object. Now, a 0:22:05.400 --> 0:22:08.760 normal piece of cloth would betray that something was in 0:22:08.800 --> 0:22:11.159 fact underneath it. You would be able to see the 0:22:11.160 --> 0:22:15.120 cloth bunched up and folded over the contours of the object. 0:22:15.520 --> 0:22:20.240 But this new tech wouldn't appear to do that, assuming 0:22:20.280 --> 0:22:23.159 you could see in the microwave range. According to the 0:22:23.200 --> 0:22:27.800 senior author of the study, bubbacar Conte, the carpet would 0:22:27.840 --> 0:22:30.840 create the illusion that it was laying flat on the 0:22:30.880 --> 0:22:34.320 table as if nothing were under it at all, and 0:22:34.400 --> 0:22:39.520 it used taflon and ceramics as dielectrics, a dielectric is 0:22:39.520 --> 0:22:43.760 a material that acts as a poor conductor or an insulator. 0:22:43.800 --> 0:22:47.920 When you subject a dielectric to an electric field, very 0:22:47.920 --> 0:22:51.600 little current will flow in the material because there's no 0:22:51.760 --> 0:22:56.440 free electrons in the material to have current flowing. However, 0:22:56.760 --> 0:23:01.280 the material does become electrically polarized. The positive charges of 0:23:01.320 --> 0:23:04.840 the of the dielectric are attracted to the electric field 0:23:05.119 --> 0:23:08.520 and the negative charges in the dielectric are repulsed by it, 0:23:08.800 --> 0:23:13.080 and this separation of charge it's minute, but it reduces 0:23:13.119 --> 0:23:17.359 the electric field within the dielectric anyway. The combination of 0:23:17.400 --> 0:23:22.159 teflon and ceramics scatter the microwaves to mimic a reflection 0:23:22.240 --> 0:23:25.639