Speaker 1: Get in tech with technology with tech Stuff from half
Speaker 1: stuff works dot com. Hey there, and welcome to tech Stuff.
Speaker 1: I'm your host, Jonathan Strickland. I'm an executive producer here
Speaker 1: at how Stuff Works in a love all things tech.
Speaker 1: And not only do I love all things tech, I
Speaker 1: also love science fiction. Those who have listened to the
Speaker 1: show for a while know that I have a deep
Speaker 1: love of science fiction, and no small part due to
Speaker 1: my parents, who are both science fiction fans and authors.
Speaker 1: And one of my favorite gadgets in science fiction is
Speaker 1: the cloaking device. Now, the earliest example I can remember
Speaker 1: from my own personal experience is from Star Trek, because
Speaker 1: the Klingons and the Romulans in Star Trek had access
Speaker 1: to technology that could render their ships not just undetectable
Speaker 1: by sensors, but completely invisible. So this goes beyond stealth technology,
Speaker 1: which uses materials and architecture to confound devices like radar.
Speaker 1: I'll talk more about that later, but this would be
Speaker 1: a technology that could turn an entire spacecraft completely invisible,
Speaker 1: allowing light and other electromagnetic energy to bend around it
Speaker 1: in such a way as to seemingly pass through it entirely,
Speaker 1: so you can think kind of like light in this sense,
Speaker 1: being like flowing water. Imagine a stream of water flowing downhill,
Speaker 1: and you place a rock in the middle of that stream,
Speaker 1: and the water will part around that rock and come
Speaker 1: back together on the other side. And so if you're
Speaker 1: just a little further downstream, you would never know there
Speaker 1: was a rock there in the first place, because the
Speaker 1: way the water is flowing, it looks like it's been
Speaker 1: moving in a straight line the whole time. That's simply
Speaker 1: the same kind of concept for cloaking devices, except instead
Speaker 1: of water, we're talking about electromagnetic radiation. That's the basic premise, right,
Speaker 1: It somehow is able to bend energy so that it
Speaker 1: flows around the object and continues on its original trajectory
Speaker 1: as if nothing were there to begin with. To an
Speaker 1: outside observer relying upon this type of energy to quote
Speaker 1: unquote see the cloaked object, it would seem as if
Speaker 1: nothing were there at all. When it comes to science fiction,
Speaker 1: writers tend to rely upon terms that sound vaguely futuristic
Speaker 1: and scientific, but typically they don't actually mean anything. Most
Speaker 1: of them rely on fictional energies or materials, but there
Speaker 1: are real world examples of cloaking devices that I would
Speaker 1: like to talk about. Before I jump into that, I
Speaker 1: need to make one thing very clear. The cloaking devices
Speaker 1: and technologies I'll be covering will not turn objects invisible
Speaker 1: to the naked eye. They don't work at that end
Speaker 1: of the electromagnetic spectrum, at least not the ones that
Speaker 1: are on the higher tech end of it. Some of
Speaker 1: them use optical illusions to make it seem that way.
Speaker 1: This little fact, however, sometimes gets lost in reporting of
Speaker 1: cloaking technology. The headlines are too good to say new
Speaker 1: cloaking device makes it a reality, or sometimes the information
Speaker 1: is included in the reporting and then everyone gets a
Speaker 1: little bummed out about it because it's not a quote
Speaker 1: unquote real cloaking device. I'll also cover a few technologies
Speaker 1: that create this illusion of a cloaking device under specific criteria,
Speaker 1: because the solution is actually a kind of clever and
Speaker 1: a good place to start is with stealth technology. Now
Speaker 1: I've covered stealth tech in a previous episode of Tech Stuff,
Speaker 1: but I'm gonna go and cover some of it again
Speaker 1: right here. I'm just gonna go really light on history,
Speaker 1: because you can listen to the other episode and get
Speaker 1: the full story. I just want to talk about how
Speaker 1: stealth fighters and stealth bombers work from that stealth perspective. First,
Speaker 1: I'm sure you've seen pictures of these sorts of vehicles
Speaker 1: and you might notice right away that they don't appear
Speaker 1: to be invisible. You can kind of sort of totally
Speaker 1: see them. One makes them stealth isn't there ability to
Speaker 1: disappear in front of your very eyes, because they don't
Speaker 1: have that, but rather their ability to evade detection via radar. Now,
Speaker 1: radar works like echolocation. Electromagnetic symbol signals rather beam out
Speaker 1: from a transmitter, and then those signals collide with an
Speaker 1: object like a jet. Some of those signals bounce off
Speaker 1: the jet and bounce back towards the transmitter. You also,
Speaker 1: besides the transmitter, have a receiver, and the receiver picks
Speaker 1: up these returning signals and registers that there's an aircraft
Speaker 1: present in the airspace. If there's a change in wavelength
Speaker 1: the radio In the radio signals, you can also deduce
Speaker 1: if the aircraft is moving toward you or away from you.
Speaker 1: If the radio waves are longer than they were when
Speaker 1: you blasted them out, that means the objects moving away.
Speaker 1: If they're elongated. In other words, if the wavelengths are
Speaker 1: shorter the object is coming toward you. This is the
Speaker 1: Doppler of act. It's the same sort of thing you
Speaker 1: might experience if a car with a siren blasting drives
Speaker 1: past you. It sounds higher pitched as the car is
Speaker 1: coming towards you, and lower pitched as the car is
Speaker 1: moving away from you. And that's because the sound waves
Speaker 1: themselves are being compressed in front of the vehicle as
Speaker 1: it moves towards you, and they're elongated as the vehicle
Speaker 1: moves away from you. Same sort of thing can happen
Speaker 1: with electromagnetic waves, and like I said, it's called the
Speaker 1: Doppler effect. Also, by looking at the delay between when
Speaker 1: the radio waves blasted out from the transmitter and when
Speaker 1: the returning waves were picked up by the receiver, you
Speaker 1: know how far away the aircraft is because the radio
Speaker 1: waves travel at a constant speed. So by knowing how
Speaker 1: much time has passed, you know how how far away
Speaker 1: the aircraft is. Right, you just measure the amount of
Speaker 1: time that has passed and then you do a quick
Speaker 1: calculation to say, well, it traveled x distance in this
Speaker 1: amount of time. Let's take half of that at because
Speaker 1: the signals traveled out and then they traveled back, so
Speaker 1: half of the full length of travel time is how
Speaker 1: far away the aircraft is, roughly speaking, So stealth technology
Speaker 1: is all about foiling that process. The two major methods
Speaker 1: involved creating a radar absorbent surface, something that is very
Speaker 1: efficient at absorbing electromagnetic radiation, and then making sure that
Speaker 1: the aircraft has a particular shape to reflect any other
Speaker 1: radio waves in different directions than the origin source. The
Speaker 1: absorbent surface is a composite material that's made of lots
Speaker 1: of different lightweight stuff that's really efficient at absorbing radio energy.
Speaker 1: If the aircraft absorbs the radio waves from a radio antenna,
Speaker 1: nothing would bounce back and nothing would get picked up
Speaker 1: by the receiver. So if you had a perfect absorbent material,
Speaker 1: it would just soak in all those radio waves. Nothing
Speaker 1: would ever return, so it would never show up on radar.
Speaker 1: But we don't have anything that's quite that perfect. The
Speaker 1: plane's shape plays a really big part in this as well,
Speaker 1: because a radio wave will bounce off of surfaces and
Speaker 1: return at an angle, just as if you were to bounce,
Speaker 1: say a cue ball inside a pool table. You know,
Speaker 1: if you choose different angles. When you're bouncing the cue ball,
Speaker 1: it's going to react in a different way. It's going
Speaker 1: to bounce off in a different direction. Um And once
Speaker 1: you know that relationship, then you can start to design
Speaker 1: surfaces to bounce those radio waves off in directions that
Speaker 1: are not going to go back toward the receiver. The
Speaker 1: shape of stealth vehicles tends to include a lot of
Speaker 1: curved surfaces that seemingly wonky angles. Sometimes you'll get some
Speaker 1: very flat surfaces as well, but they'll be in odd
Speaker 1: positions relative to one another. And this is all to
Speaker 1: try and foil those radio waves, to make them bounce
Speaker 1: in a way that's not going to go back to
Speaker 1: where the receiver is. So the electromagnetic radiation does not
Speaker 1: pass through the air craft, it doesn't bend around it
Speaker 1: the way you would say a cloaking device would do,
Speaker 1: but it does allow you to have a way of
Speaker 1: eluding radar detection. So it's not really the same sort
Speaker 1: of technology that you would find in science fiction. Now,
Speaker 1: there are other ways you can simulate a cloaking device,
Speaker 1: such as a method that has been used in several
Speaker 1: marketing campaigns, and that as to use a series of
Speaker 1: cameras and screens to simulate a cloaking device. The concept
Speaker 1: is pretty simple. You start with an object. Let's say
Speaker 1: it's a Mercedes Benz F Cell concept vehicle, because Mercedes
Speaker 1: actually did do this as a marketing stunt back in
Speaker 1: two thousand twelve. The F Cell, by the way, was
Speaker 1: a fuel cell prototype vehicle, and I've talked all about
Speaker 1: fuel cells in other episodes. Pretty fascinating technology anyway. Imagine
Speaker 1: that you cover one full side of this vehicle, let's
Speaker 1: say the driver's side of the vehicle, with a mesh
Speaker 1: that has a bunch of l e d s in
Speaker 1: it to act as a screen, so the side of
Speaker 1: the car turns into a low resolution l e ED
Speaker 1: television screen. On the other side of the vehicle, you
Speaker 1: mount a camera and the camera captures everything that's on
Speaker 1: that side of the vehicle. So it's facing out from
Speaker 1: the passenger side, so it would be the same kind
Speaker 1: of point of view as a passenger would have if
Speaker 1: he or she was looking directly out of their window.
Speaker 1: The video feed you pick up from this camera gets
Speaker 1: fed directly to the other side, to the l e
Speaker 1: ED screen side of the vehicle, and it displays whatever
Speaker 1: the cameras have picked up, so you end up getting
Speaker 1: this illusion. If you stand on the screen side of
Speaker 1: the vehicle, it's almost like you're looking through it, though
Speaker 1: at a lower resolution than reality, so it looks a
Speaker 1: little jankie. Although you could argue that's kind of like
Speaker 1: a cloaking effect you see in some science fiction shows
Speaker 1: and movies where you've got that little shimmery effect. It's
Speaker 1: kind of like that, but less cool than that. Not
Speaker 1: so predator. It's a little more uh noticeable. I've seen
Speaker 1: similar setups to make an effect in costumes that make
Speaker 1: it look like a person has a hole straight through
Speaker 1: their torso. It's a pretty cool thing to do. It's
Speaker 1: actually really easy if you've got two iPads. For example,
Speaker 1: Uh they typically will wear a screen on their chest,
Speaker 1: and then you can put a camera on your back
Speaker 1: and the camera captures live video from whatever is going
Speaker 1: on behind you, feeds it to the screen that's hanging
Speaker 1: on front of your torso, and you cut a hole
Speaker 1: in a shirt so that it it goes right around
Speaker 1: the screen and the screen is showing everything that's happening
Speaker 1: behind you. So the illusion is that you've got a
Speaker 1: hole in your torso and people can look right through
Speaker 1: it and see what's happening on the other side. Uh.
Speaker 1: Like I said, you could actually do this in a
Speaker 1: pretty easy way. I saw a clever video that used
Speaker 1: a pair of iPad two tablet to make this effect
Speaker 1: on both sides. The guy who published the video's name
Speaker 1: is Mark Rober. He published the video on YouTube in
Speaker 1: October two thousand eleven, so you can actually find this
Speaker 1: video if you want to see how he did it.
Speaker 1: But he said he used two iPad two's, one to
Speaker 1: face out in front and one to face out in back.
Speaker 1: So the but the screens were facing outward on both sides.
Speaker 1: One facing one had you know, the back of the
Speaker 1: iPad two was against his chest. The other one had
Speaker 1: the back of the second iPad two against his back.
Speaker 1: And what he did was he just set up a
Speaker 1: FaceTime call between the two iPads, so each iPad was
Speaker 1: showing the screen of the other iPads camera and by
Speaker 1: doing that, you just have this live feed on either side.
Speaker 1: So it worked on either side of the person. You
Speaker 1: could stand in front of them and you're actually looking
Speaker 1: at the hole that's showing on showing what's going on
Speaker 1: behind the person, or you could be behind them, and
Speaker 1: you'd be looking through the hole and you see what's
Speaker 1: going on in front of that person, so you get
Speaker 1: this illusion that you have a hole going through a
Speaker 1: solid Torso it's great if you want to do a
Speaker 1: creepy zombie style character at Halloween. I've always wanted to
Speaker 1: do this, but I've never actually gone out to buy
Speaker 1: a couple of iPads just to do a costume. It
Speaker 1: seems like it might be a little much for me,
Speaker 1: but still pretty neat. However, again, that's not a true
Speaker 1: cloaking device. I don't think anyone would ever argue that.
Speaker 1: And for one thing, any set up where you've got
Speaker 1: a screen and a camera means that you really only
Speaker 1: have one side prepared to be quote unquote cloaked. So
Speaker 1: if you're on the other side of the device or
Speaker 1: the structure or whatever it is, you would totally see
Speaker 1: the object or the person standing there because you would
Speaker 1: be on the camera side, not the screen side. It's
Speaker 1: kind of like being backstage in a show. You see
Speaker 1: how everything works, so it's not truly cloaking. But next,
Speaker 1: we're gonna talk about bending light and something you can
Speaker 1: actually do. We can bend light optical lenses do that,
Speaker 1: so if you wear glasses or contacts, you rely on
Speaker 1: something that bends light already, and I talked about the
Speaker 1: physics of optical lenses in an episode not too far back.
Speaker 1: But if you're clever and you use the right sequence
Speaker 1: of lenses at the proper distance from one another, you
Speaker 1: can create an optical illusion equal to a type of cloaking.
Speaker 1: And that's the secret behind the original Rochester Cloak, so
Speaker 1: called because it was developed at the University of Rochester.
Speaker 1: Now I'll talk more about their approach to cloaking in
Speaker 1: just a second, but first let's take a quick break
Speaker 1: to thank our sponsor. The version of the Rochester Cloak
Speaker 1: I studied had four lenses arranged in a straight line
Speaker 1: with several inches separating each lens. So think of it
Speaker 1: as lens one, two, three, four, And let's say that
Speaker 1: for the purposes of this description, that the lens closest
Speaker 1: to someone who's going to look through the Rochester Cloak
Speaker 1: is lens number one. The furthest lens from the viewer
Speaker 1: is lens number four. Now, in the demonstration I viewed
Speaker 1: the uh the the backdrop for this was a grid pattern,
Speaker 1: So there was actually a grid pattern in the very back,
Speaker 1: and the purpose of that was to provide a reference
Speaker 1: so that when you passed things between the lenses in
Speaker 1: order to create this cloaking effect, you would still see
Speaker 1: the grid pattern in the background, and it gives this
Speaker 1: illusion that you have an unbroken uh line of sight
Speaker 1: even when an object is passing between the lenses. So
Speaker 1: a casual glance through the lenses, it makes it seem
Speaker 1: like light has just passed through the series of lenses
Speaker 1: without bending. Like from from lens for two lens one,
Speaker 1: the effect you get is that the light has just
Speaker 1: traveled straight through those lenses, because the grids in the
Speaker 1: back remains straight, and that becomes your reference point. Right
Speaker 1: You're looking at the grids and you're thinking, well, the
Speaker 1: lines look straight, so the light's not really being bent
Speaker 1: by these lenses. At least that's the optical illusion I have.
Speaker 1: But what is really happening is some light gymnastics. And
Speaker 1: I don't mean low impact gymnastics. I mean gymnastics involving light.
Speaker 1: Each lens bends the light in a slightly different way,
Speaker 1: concentrating or spreading out the light, so that if you
Speaker 1: were to place a small object between Lens one and
Speaker 1: lens too, So the first two lenses it would look
Speaker 1: as if you could see right through the object with
Speaker 1: some limitations. The big limitation is that the cloaking effect
Speaker 1: only works on the edges of the viewing area of
Speaker 1: the lens. So if you think of the lens as
Speaker 1: a circle, the closer you get to the center of
Speaker 1: that circle, the closer you're getting to the point where
Speaker 1: you're going to be able to actually see that object.
Speaker 1: But if it's on the the edge of the center,
Speaker 1: then it seems like you can look right through the object.
Speaker 1: So uh, it's because the light is being bent in
Speaker 1: such a way that that light is concentrated on the
Speaker 1: center of lens number one before that lens actually spreads
Speaker 1: the light out again towards your eye. And each of
Speaker 1: these lenses was carefully selected so that it would manipulate
Speaker 1: the light where it seems like you're looking at an
Speaker 1: unaltered image. Right, it looks like you're looking at that
Speaker 1: grid and the lines are straight. In fact, the way
Speaker 1: that the light is being bent by the lens, if
Speaker 1: you were to look through lens number two instead of
Speaker 1: lens number one, the backdrop would look very different. It
Speaker 1: wouldn't look like a grid of straight lines. It's because
Speaker 1: each lens is bending light in a specific way that
Speaker 1: you're able to create this effect. So it doesn't matter
Speaker 1: if the object you put between lens one and lens
Speaker 1: two is a pencil or a finger, it seems like
Speaker 1: there is nothing there in front of you, or that
Speaker 1: the middle of the object has disappeared, like if you
Speaker 1: can see the object on either side of the lens,
Speaker 1: like if it extends out to either edge, it would
Speaker 1: look like the middle is just suddenly gone. But again,
Speaker 1: this is all just through optics, so it's somewhat limited
Speaker 1: as it's entirely dependent upon your frame of reference. It
Speaker 1: depends upon the viewer looking through the lens. If you
Speaker 1: were to step to the side and look at this
Speaker 1: apparatus from ninety degrees on, you would observe that there's
Speaker 1: no cloaking effect at all. The light your eyes would
Speaker 1: detect has not passed through that array of lenses, so
Speaker 1: all you would see is someone placing an object between
Speaker 1: two lenses, and it would not disappear. It would just
Speaker 1: be right there, so there'd be nothing special from your perspective.
Speaker 1: There are similar projects that use cameras, mirrors, and displays
Speaker 1: to create this type of illusion, but again they're dependent
Speaker 1: upon your frame of reference and perspective. If you step
Speaker 1: outside that frame of reference and truth settles in, then
Speaker 1: you notice that the thing is not really invisible or transparent.
Speaker 1: This is kind of like having a magician hide something
Speaker 1: behind a little curtain, and because you're looking at the curtain,
Speaker 1: you cannot see what's going on behind it. But if
Speaker 1: you were watching from the side of the magician, you
Speaker 1: can see how the trick was done, which is not
Speaker 1: much fun, but it does show that the optical illusion
Speaker 1: depends upon certain criteria to work, specifically where you are
Speaker 1: looking from. In two thousand seventeen, Toyota applied for a
Speaker 1: patent titled Apparatuses and Methods for making an Object Appear Transparent.
Speaker 1: So was this a way to turn an entire car
Speaker 1: invisible allah James Bond's Aston Martin v. Twelve Vanquished and
Speaker 1: Die Another Day. Not quite. This is a system meant
Speaker 1: to help the driver of the car. It's not meant
Speaker 1: for people outside the vehicle. Toyota's approach is a method
Speaker 1: to make certain features inside the car appear transparent to
Speaker 1: the driver, so that the driver can have an unimpeded
Speaker 1: view of the environment around the car. Specifically, the objects
Speaker 1: that were meant to be turned transparent were the A
Speaker 1: pillars inside the vehicle. Now, the pillars in a car
Speaker 1: are the supports of a car's window area, sometimes also
Speaker 1: called the greenhouse. Pillars are divided up as A, B, C,
Speaker 1: and if the vehicle's big enough, sometimes D pillars. The
Speaker 1: B pillars are sometimes called posts. Those are the ones
Speaker 1: that are on the side of the vehicle. Uh. The
Speaker 1: A pillars are the sections on either side of the
Speaker 1: windshield that support the windshield and connect to the top
Speaker 1: of the car in order to meet crash safety standards.
Speaker 1: Those pillars can be pretty wide to provide the necessary
Speaker 1: structural support, but that means they block some of your
Speaker 1: view while you're driving. So it's that section of a
Speaker 1: car that separates the front windshield from your side mirror
Speaker 1: or your side window. Rather so that that poe, that
Speaker 1: pillar is what Toyota was thinking about, like, how can
Speaker 1: we make it so that you can see through that
Speaker 1: pillar and thus have a better view out that side
Speaker 1: of your vehicle, so that you really don't have an
Speaker 1: impeded view from the front all the way over to
Speaker 1: your side window. How do you get rid of that
Speaker 1: gap from your vision. Well, according to the patent, Toyota's
Speaker 1: system redirects light using mirrors so that the light projects
Speaker 1: on the pillar itself, creating the illusion that the pillar
Speaker 1: is transparent and removing that gap from your visibility. And
Speaker 1: because it's a patent, anyone is free to look it
Speaker 1: over and read about the technology Toyota developed. So if
Speaker 1: you want to do it, if you want to read
Speaker 1: about some pretty complicated concepts and optics, I have the
Speaker 1: patent number for you. It is a long one, so
Speaker 1: get ready. The patent application number is US two thousand,
Speaker 1: seventeen zero two two seven seven eight one a one.
Speaker 1: So if you put that into a patent search, you're
Speaker 1: gonna pull this up and you can read all about
Speaker 1: how Toyota proposes this technology be implemented. But what about
Speaker 1: a cloak more in line with the invisibility cloak in
Speaker 1: Harry Potter. In J. K. Rowling's books, characters make use
Speaker 1: of the invisibility cloak to snoop in on important exposition.
Speaker 1: And in that world it all works via magic, which
Speaker 1: is great because there's no need to explain anything. It
Speaker 1: just works. But is there anything like that in the
Speaker 1: real world. Well it's not nearly so dramatic as that,
Speaker 1: but the U see San Diego Jacob's School of Engineering
Speaker 1: played host to a cool project that reminds me of
Speaker 1: the invisibility cloak in Harry Potter. A research team published
Speaker 1: a study in a journal called Progress in Electromagnetics Research
Speaker 1: that detailed a cool technology they nicknamed a carpet cloak.
Speaker 1: And with this tech, you could put an object on
Speaker 1: a flat surface, like a table. You could then lay
Speaker 1: the carpet cloak on top of this object. Now, a
Speaker 1: normal piece of cloth would betray that something was in
Speaker 1: fact underneath it. You would be able to see the
Speaker 1: cloth bunched up and folded over the contours of the object.
Speaker 1: But this new tech wouldn't appear to do that, assuming
Speaker 1: you could see in the microwave range. According to the
Speaker 1: senior author of the study, bubbacar Conte, the carpet would
Speaker 1: create the illusion that it was laying flat on the
Speaker 1: table as if nothing were under it at all, and
Speaker 1: it used taflon and ceramics as dielectrics, a dielectric is
Speaker 1: a material that acts as a poor conductor or an insulator.
Speaker 1: When you subject a dielectric to an electric field, very
Speaker 1: little current will flow in the material because there's no
Speaker 1: free electrons in the material to have current flowing. However,
Speaker 1: the material does become electrically polarized. The positive charges of
Speaker 1: the of the dielectric are attracted to the electric field
Speaker 1: and the negative charges in the dielectric are repulsed by it,
Speaker 1: and this separation of charge it's minute, but it reduces
Speaker 1: the electric field within the dielectric anyway. The combination of
Speaker 1: teflon and ceramics scatter the microwaves to mimic a reflection
Speaker 1: pattern of a flat surface. So while there are actual
Speaker 1: deformations in this carpet cloak, the way the material scatters
Speaker 1: electromagnetic radiation makes it appear as if it is flat.
Speaker 1: So in reality it is folded around an object, but
Speaker 1: from a microwave perspective, it's as if it's a perfectly
Speaker 1: flat piece of cloth. If you were to reach out
Speaker 1: and touch the material, you would actually feel the spots
Speaker 1: where it covered the object. But again, this was entirely
Speaker 1: on the microwave scale, not visible light, so to our
Speaker 1: eyes everything would seem exactly the same. Microwaves have a
Speaker 1: wavelength of about ten to the minus two meters, meaning
Speaker 1: they are on the centimeter scale, but visible light has
Speaker 1: wavelengths closer to point five times ten to the minus
Speaker 1: six meters. I mean, they have a much smaller wavelength
Speaker 1: and therefore a higher frequency. Designing material that can scatter
Speaker 1: visible light requires more precision than something for microwaves. The
Speaker 1: cloak carpet falls into a general category of stuff we
Speaker 1: call meta materials, and those are super cool. So let's
Speaker 1: talk about what they are and how they work right
Speaker 1: after we take this break to thank our sponsor. So
Speaker 1: what is a meta material? Well, they're different kinds, but
Speaker 1: two of the defining features are that one this is
Speaker 1: stuff that's made by humans, so you do not find
Speaker 1: meta materials in nature, and two, they tend to have
Speaker 1: properties that are either uncommon or un heard of in nature.
Speaker 1: So it's stuff we make what acts differently than stuff
Speaker 1: we encounter in the natural world. Menty materials get their
Speaker 1: unique properties not just from the type of stuff they
Speaker 1: are made from, but also their actual physical structure, which
Speaker 1: makes them different from natural elements. So, for example, if
Speaker 1: you were to go panning for gold and you found
Speaker 1: a few gold nuggets, pure gold nuggets in a stream,
Speaker 1: Those pure gold nuggets would have the same general properties
Speaker 1: as say, a bar of pure gold or a piece
Speaker 1: of pure gold jewelry. They would all be in different
Speaker 1: shapes and sizes, but their properties would remain exactly the same.
Speaker 1: It would still behave as gold, But a meta materials
Speaker 1: properties depend at least partly on the structure of the
Speaker 1: meta material itself. And by structure, i'm talking about repeated
Speaker 1: patterns that are all the way down to the nano scale,
Speaker 1: or maybe even further down to the atomic scale. A
Speaker 1: nanometer is one billionth of a meter, and a human
Speaker 1: hair can average about one hundred thousand nanometers in diameter.
Speaker 1: So we are talking super small here, so small that
Speaker 1: a light microscope will be of no help to you
Speaker 1: if you want to look at this stuff, because the
Speaker 1: light wavelengths are actually bigger than the things you're trying
Speaker 1: to look at. To bend electromagnetic radiation, you have to
Speaker 1: create these tiny, repeating patterns of structures inside this material.
Speaker 1: What's more, the structures need to be at a scale
Speaker 1: that's smaller than the length of the wavelength of electromagnetic
Speaker 1: radiation that you plan to manipulate. Now, there are a
Speaker 1: few ways that meta materials could manipulate electromagnetic radiation. One
Speaker 1: way is to create what is called left handed material
Speaker 1: and as a left hander, I really appreciate this. Left handedness.
Speaker 1: When it comes to meto materials refers to two attributes,
Speaker 1: permitivity and permeability. Permitivity refers to the resistance that is
Speaker 1: encountered when an electric field interacts with this material. Permeability
Speaker 1: refers to the degree of magnetization within a material that's
Speaker 1: interacting with a magnetic field. If both the permitivity and
Speaker 1: the permeability of a substance is negative, that substance is
Speaker 1: said to be left handed. Now, you can also have
Speaker 1: single negative meta materials, in which either the permitivity or
Speaker 1: the permeability is negative, but not both. Most stuff in nature, however,
Speaker 1: falls into double positive category, meaning both permitivity and permeability
Speaker 1: is positive. So meta materials fly in the face of nature.
Speaker 1: Take that, nature, I think you're so big. The carpet
Speaker 1: cloak is an example of meta materials that have the
Speaker 1: capability of bending microwaves around them as if the material
Speaker 1: wasn't there. Though, as I mentioned earlier, right now scientists
Speaker 1: are working on wavelengths that are in that centimeter range
Speaker 1: or maybe as small as near infrared, which is still
Speaker 1: a much larger wavelength than visible light. They have not
Speaker 1: managed anything that would work in the visible range. In
Speaker 1: order to do that, they would have to build these
Speaker 1: repeated structured patterns at a very tiny scale. We're talking
Speaker 1: like ten to twenty nanometers max. Developing that technique will
Speaker 1: be a challenge, and making enough of it to say
Speaker 1: code a jet might be outside the realm of possibility,
Speaker 1: And that phrase visible range is also important. It might
Speaker 1: be really tricky or maybe even impossible to design a
Speaker 1: meta material that can work across the entire visible spectrum
Speaker 1: of light wavelengths. We might be able to create materials
Speaker 1: that allow certain types of light to bend around it
Speaker 1: while it still reflects other wavelengths. Such a material might,
Speaker 1: let's say, let red light pass right through it, but
Speaker 1: reflect all of the wavelengths of light. Now, that would
Speaker 1: be a pretty cool way to create a gel for
Speaker 1: a theater light I imagine, But it doesn't turn something
Speaker 1: completely invisible. It just means that you would have no
Speaker 1: red reflected back from that particular object. All the stuff
Speaker 1: you would see would not have any red in it,
Speaker 1: and all the red light would go on to the
Speaker 1: other side. In a similar vein, you wouldn't be able
Speaker 1: to manipulate all wavelengths of electromagnetic radiation with a basic
Speaker 1: meta material. So while you could conceivably create a material
Speaker 1: that could allow visible light to bend around it, other
Speaker 1: types of electromagnetic radiation might remain unaffected, meaning you would
Speaker 1: still be able to quote unquote see the object using
Speaker 1: a different wavelength, like radar. So you might have an
Speaker 1: invisible jet like Wonder Woman, but it will still show
Speaker 1: up on people's sensors. Meta materials aren't necessarily restricted to
Speaker 1: electromagnetic wave manipulation. However, there are scientists and engineers making
Speaker 1: meta materials that will interact with other types of waves,
Speaker 1: including physical waves like sound, owned waves, or waves in
Speaker 1: the ocean. Imagine a material that can redirect sound waves
Speaker 1: with incredible efficiency. You could design a space that amplifies
Speaker 1: or nullifies sound. Or imagine a building made out of
Speaker 1: meta materials that can redirect seismic waves so it's as
Speaker 1: if these seismic waves just passed through the building. So
Speaker 1: if an earthquake were shaking everything around the building, the
Speaker 1: waves would actually move through the physical structure as if
Speaker 1: nothing were there at all. And it could remain unaffected
Speaker 1: by the earthquake. Much of the work and meta materials
Speaker 1: does not have the goal of creating magically invisible matter. Rather,
Speaker 1: it's to manipulate electromagnetic radiation to make technologies more effective.
Speaker 1: For example, imagine solar cells that are made from materials
Speaker 1: that capture light with greater efficiency, so we lose less
Speaker 1: of the Sun's energy due to reflections off the solar cell.
Speaker 1: Or imagine radio receivers that are more effective at picking
Speaker 1: up week signals due to their physical structure or going
Speaker 1: to the physical wave examples. Imagine a perfectly soundproofed room
Speaker 1: that absorbs all sound from the outside, which I would
Speaker 1: love to have so that every time someone walks in
Speaker 1: or out of the door that's next to the studio,
Speaker 1: it doesn't interrupt me and I don't have to say
Speaker 1: things all over again. Maybe I have some personal stake
Speaker 1: in this now. I recently read a report about a
Speaker 1: team that made a meta material that's effective with sound waves,
Speaker 1: and this research comes out of Pennsylvania State University. Researcher
Speaker 1: Amanda D. Hanford used meta materials to bend sound waves
Speaker 1: around an object as if the object were not there,
Speaker 1: and if you were to blast this object with sound waves,
Speaker 1: the sound waves would continue onward as if there was
Speaker 1: nothing in their way, so you wouldn't get any echoes
Speaker 1: back from that object. And Hanford's meta material works under water.
Speaker 1: That means such a material could shield an object from sonar. SONAR,
Speaker 1: which was originally an acronym that stood for Sound Navigation
Speaker 1: and ranging, uses sound as an echo location strategy. It's
Speaker 1: essentially the sound equivalent to radar. Most radio waves do
Speaker 1: not work so well underwater, but sonar is a different story.
Speaker 1: Sound travels very well underwater, so for certain applications, such
Speaker 1: as the navigation equipment aboard a submarine, sonar is incredibly useful.
Speaker 1: But if you can shield objects from sonar, then there's
Speaker 1: no way to know that there's an object there. A
Speaker 1: submarine's sonar equipment wouldn't detect this object, potentially resulting in
Speaker 1: a crash. Or you could conceivably use meta materials to
Speaker 1: hide a full submarine, creating a Red October sort of situation,
Speaker 1: which is pretty cool. Now, when we ever have a
Speaker 1: cloaking device like the ones in science fiction films, I'm
Speaker 1: not gonna say it will never happen. Science and technology
Speaker 1: can do amazing things, and it may be that we
Speaker 1: solve this challenge using those tools, but it's going to
Speaker 1: take some time if it is possible. In the meantime,
Speaker 1: will probably see some really amazing applications of these various
Speaker 1: strategies for stuff that is just as cool as turning
Speaker 1: a cling on bird of prey invisible. And that wraps
Speaker 1: up this discussion about cloaking devices. I hope you enjoyed it.
Speaker 1: If you have any suggestions for future episodes of tech Stuff,
Speaker 1: right me. My email address is tech Stuff at how
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