Speaker 1: Welcome to Tech Stuff, a production from I Heart Radio.
Speaker 1: Hey there, and welcome to tech Stuff. I'm your host,
Speaker 1: Jonathan Strickland. I'm an executive producer with I Heart Radio
Speaker 1: and how the tech are you? All right? I'm gonna
Speaker 1: start this episode with a rant that arguably is almost
Speaker 1: moot at this point and is certainly tangion shoaled to
Speaker 1: the episode, But it has to do with bookstores and
Speaker 1: how they classify types of books. Now, if you've ever
Speaker 1: been in a bookstore, like a brick and mortar bookstore,
Speaker 1: and then you've looked around at the various categories like mystery, history, romance,
Speaker 1: all that sort of stuff, chances are at some point
Speaker 1: you encountered a section that was called something like science
Speaker 1: fiction and fantasy, and you would have your swords all
Speaker 1: mixed up with your lasers. In a quick shout out
Speaker 1: to the podcast Sword and Laser, which is pretty dark
Speaker 1: and great. Ut I've always been kind of grouchy about this.
Speaker 1: I felt that while science fiction and fantasy both fall
Speaker 1: into the realm of speculative fiction, they aren't the only ones.
Speaker 1: I mean a lot of horror falls into that as well,
Speaker 1: But horror doesn't tend to be grouped with science fiction
Speaker 1: and fantasy. And of course psychological horror might not fit
Speaker 1: into speculative fiction, like a person going on some sort
Speaker 1: of rampage or something, but the kind of horror where
Speaker 1: a fear feeding alien who looks like a clown definitely
Speaker 1: falls into that category. But still horror gets its own section.
Speaker 1: So why not science fiction and fantasy? And I guess
Speaker 1: I'm touchy about this because my parents are authors. Dad
Speaker 1: in particular has written a lot of science fiction, fantasy,
Speaker 1: and horror novels, as well as mystery novels and also
Speaker 1: young adult novel You know what, Dad's written a lot
Speaker 1: of stuff, and I just thought it's weird that his
Speaker 1: science fiction books and fantasy books would appear side by
Speaker 1: side in the same section. In fact, his agent and
Speaker 1: publishers were so concerned about this that at one point
Speaker 1: he had to write under a pen name for a
Speaker 1: science fiction book so that it wouldn't be right next
Speaker 1: to his fantasy books. Now, none of that really matters
Speaker 1: for this episode, except there is an element that can
Speaker 1: be found both in fantasy books and science fiction books
Speaker 1: as well as other media that I'm going to talk
Speaker 1: about today, and that's stuff. What turns you invisible. Now,
Speaker 1: in fantasy, it might be an actual cloak, so you
Speaker 1: really have a cloaking an invisibility cloak. It might be
Speaker 1: a ring that at some point you can't have to
Speaker 1: chuck into a volcano. It might be a spell or
Speaker 1: a potion, whereas in science fiction it might be some
Speaker 1: sort of technology that's incorporated in say a spaceship, that
Speaker 1: allows it to pass undetected as it sneaks up on
Speaker 1: an enemy or encounters an alien world. Now, I thought
Speaker 1: we might talk a bit about tech intended to grant
Speaker 1: invisibility in the real world. We've got some real world
Speaker 1: examples of stuff that does this to a certain degree,
Speaker 1: though spoiler alert, we do not have a technology that
Speaker 1: can cover the entire visual spectrum of light that would
Speaker 1: work like an invisibility cloak or something. There are folks
Speaker 1: working on it, but we're definitely not there yet. However,
Speaker 1: we do have some really interesting examples that at least
Speaker 1: brush up against invisibility that we'll talk about. Now, before
Speaker 1: we dive into the various technologies, let's talk about how
Speaker 1: vision works and chat a bit about light. So, way
Speaker 1: back in the day, smarty pans philosopher types tried to
Speaker 1: suss out what is light and how does vision work.
Speaker 1: Pythagoras had the angle on some stuff, but when it
Speaker 1: came to how vision works, he ended up being a
Speaker 1: bit obtuse. Yes, I'm gonna throw in lots of puns
Speaker 1: and dad jokes. Anyway, Pythagoras thought that vision worked because
Speaker 1: we were effectively shooting out rays of vision with our eyeballs,
Speaker 1: like vision was something that came from us, extended out
Speaker 1: into the world and effectively lit the world around us
Speaker 1: with vision, and so these vision rays would go out
Speaker 1: and hit objects, which let us see them. So we
Speaker 1: were kind of like Superman with this heat vision, except
Speaker 1: we're just constantly shooting out this sort of light. And
Speaker 1: you might think, silly Pathagoras, wouldn't that mean we could
Speaker 1: all see in the dark. But maybe what he was
Speaker 1: saying is that, you know, some of this light that
Speaker 1: is invisible to us in the world, like we can't
Speaker 1: see it shooting out of everybody else's eyes, but the
Speaker 1: it's what comes out of our eyes and hit stuff
Speaker 1: that's already lit, and that's what lets us see it.
Speaker 1: And so he was just thinking it was an innate
Speaker 1: ability within the human eye and presumably animal eye as well.
Speaker 1: Epicurus had a totally different take on it. The philosopher
Speaker 1: known for emphasizing the pursuit of a happy life through
Speaker 1: eliminating fear and pain, which sounds nice, felt that objects
Speaker 1: themselves were emitting this light, that they were emitting this
Speaker 1: visible ray that our eyes could detect. So our eyes
Speaker 1: are detectors, but the objects themselves are emitting this, and
Speaker 1: that as a result, we could see light coming from
Speaker 1: the objects. Again, this doesn't really hold up when you're
Speaker 1: wandering around your house in the dark and you bark
Speaker 1: your ship on a coffee table. But what he was
Speaker 1: saying was that, all right, you're in a well lit area.
Speaker 1: Every single object that has this thing in it allows
Speaker 1: you to see it because it's emanating this energy that
Speaker 1: your eyes can detect. So a little closer to being
Speaker 1: correct than Pythagoras, but still missing stuff. Now you also
Speaker 1: had philosophers who started to get a little closer to
Speaker 1: what we know to be the truth that light can
Speaker 1: reflect off surfaces, bouncing off of them, or that it
Speaker 1: can pass through certain types of material like glass or water.
Speaker 1: But when it does, when light travels from that and
Speaker 1: hits something like the surface of glass or the surface
Speaker 1: of water, it bends, the light changes direction. Now these
Speaker 1: observations gradually lead to later smarty pants folks crafting lenses
Speaker 1: intended to bend light in specific ways. Not just you
Speaker 1: know it, not just it bends light, but I want
Speaker 1: to bend light so that it goes to this specific point.
Speaker 1: And an Arabic polymath in what is today known as
Speaker 1: Iraq even al hythem I figured that the human eye
Speaker 1: was doing the same sort of thing as a surface
Speaker 1: of glass or water. That light when it goes into
Speaker 1: the human eye would end up being directed. And also
Speaker 1: that light when it's going out in the world, it's
Speaker 1: bouncing off of objects, and it's the light bouncing off
Speaker 1: those objects that passes through the human eye against bent
Speaker 1: in a way where we can perceive it, and thus
Speaker 1: that's how vision works. This was around one thousand CE,
Speaker 1: or a d if you're using the more common nomenclature. Now.
Speaker 1: By the early seventeen hundreds we had Isaac Newton proposing
Speaker 1: that light was made of little corpuscles, little particles. In
Speaker 1: other words, that light really was made up of some tiny, tiny,
Speaker 1: tiny little piece of something. And it made some sense
Speaker 1: because light travels in a straight line, and it bounces
Speaker 1: off objects, just as a physical particle would do. Like
Speaker 1: if you had a tennis ball, then you threw it
Speaker 1: at a wall, it would bounce off the wall, and
Speaker 1: depending on the angle you threw the ball at and
Speaker 1: then that it hits the wall at, it's going to
Speaker 1: bounce in a specific way. Well, what Newton was saying,
Speaker 1: light appears to be doing the same thing. So it
Speaker 1: must be made of lots of tiny little tennis balls,
Speaker 1: although he didn't say tennis balls, but you know, just
Speaker 1: to continue the analogy. Others, however, would describe light as
Speaker 1: behaving like a wave, like a sound wave. And as
Speaker 1: it would turn out, both explanations were kind of right.
Speaker 1: Light behaves as a wave and a particle, but we
Speaker 1: wouldn't be sure about that for you know, a couple
Speaker 1: hundred years. But thinking about light as either a particle
Speaker 1: or a wave helps us understand what it's doing when
Speaker 1: it encounters other stuff. So let's start by thinking of
Speaker 1: as a ray of particles, and it's a ray that
Speaker 1: travels in a straight line until it encounters something else.
Speaker 1: And let's talk about how light interacts with stuff. So
Speaker 1: first up, as reflection, This is when light bounces off
Speaker 1: of a surface like a mirror or a tree where
Speaker 1: you our face. So light will bounce off a smooth
Speaker 1: surface at an angle equal to the angle of the
Speaker 1: incoming ray, making with the surface like there's a thing
Speaker 1: called the angle of incidents, and so you can predict
Speaker 1: what that angle is going to be if you're working
Speaker 1: with a perfectly smooth surface. This is what we call
Speaker 1: the law of reflection. However, we don't have perfectly smooth surfaces.
Speaker 1: If we did, then yes, you would see light bend
Speaker 1: in this way or reflect off in this way every
Speaker 1: single time. But we don't have perfectly smooth surfaces. Instead,
Speaker 1: we've got surfaces that have imperfections. And because of this,
Speaker 1: and because the wavelengths of light are very very very small,
Speaker 1: light will bounce off at all sorts of angles because
Speaker 1: again not perfectly smooth. This is why something like a
Speaker 1: tabletop won't disappear if you change your angle of view,
Speaker 1: right like if it if the light bounced in a
Speaker 1: very specific way because you had a perfectly smooth table,
Speaker 1: well that would mean that if you moved out of
Speaker 1: the angle of incidents, you would no longer see the
Speaker 1: tabletop because there will be no light bouncing off of
Speaker 1: it that you could see, which is kind of weird
Speaker 1: to think about, like the idea that something exists in
Speaker 1: one perspective, but at another it seems to not exist anymore.
Speaker 1: It does, you just can't see it. There are other
Speaker 1: reasons why it's gonna be don't have perfectly smooth tabletops.
Speaker 1: The big one being that if you had a perfectly
Speaker 1: smooth tabletop, there will be no friction. If you said
Speaker 1: anything on the surface of the tabletopic could slide all
Speaker 1: over the place. But we'll leave that beat. But then
Speaker 1: you've got absorption. Okay, so stuff can absorb light. Now,
Speaker 1: I'm sure you all know about the spectrum of light.
Speaker 1: We're gonna be talking about a lot in this episode.
Speaker 1: That's the old roy g biv red, orange, yellow, green, blue, indigo,
Speaker 1: and violet. That's the order that you would see if
Speaker 1: you were to see a rainbow. Well, that happens to
Speaker 1: be the spectrum of visible light. It's going from the
Speaker 1: longest wavelength red to the shortest violet. But we're gonna
Speaker 1: talk more about wavelengths in a little bit, and a
Speaker 1: lot of matter can absorb certain wavelengths of light. That
Speaker 1: means those wavelengths do not get reflected back at you
Speaker 1: when the light hits that object. For example, chromium, the
Speaker 1: stuff and rubies that makes them red, absorbs the green
Speaker 1: and blue wavelengths of light, so the only stuff that's
Speaker 1: getting reflected back is in the red wavelengths of light.
Speaker 1: So rubies appear red to us because the other wavelengths
Speaker 1: of light have been absorbed by the gem. If you
Speaker 1: had something that could absorb all wavelengths of light, it
Speaker 1: would look black, like pure black, as if there were
Speaker 1: avoid rather than you know, whatever the thing is. And
Speaker 1: there are special paints out there that absorbed nearly all
Speaker 1: visible light hitting them, and seeing stuff covered in that
Speaker 1: paint is trippy because it looks like there's just a
Speaker 1: a thing shaped void in a physical space. So one
Speaker 1: example I've seen as an apple that's been half painted
Speaker 1: uh with this special super uber black paint, and you
Speaker 1: put the apple on a little rotating pedestal, and what
Speaker 1: you'll see is that when the apple rotates so that
Speaker 1: the red of the apple starts to give way to
Speaker 1: the void black, it looks like half the apple is missing,
Speaker 1: but you're not seeing the inside of the apple. It's
Speaker 1: just the half the apple is just a black shape,
Speaker 1: and if it turns all the way around, it's like
Speaker 1: the apple doesn't exist anymore. You just see a black
Speaker 1: field in the shape of an apple. It's crazy. You
Speaker 1: could do that with a pumpkin and you would have
Speaker 1: a pumpkin shaped hole instead of a jack ol Internet Halloween,
Speaker 1: which would be super awesome in the daytime, wouldn't be
Speaker 1: so effective at night. But it is really neat stuff.
Speaker 1: By the way, there are different types of this ultra
Speaker 1: black paint out there. There's one kind that was heavily trademarked,
Speaker 1: and then someone else went and developed a similar kind,
Speaker 1: specifically because they felt it was wrong for someone to
Speaker 1: try and trademark a color. But yeah, that's that's a
Speaker 1: topic for another episode. Then we have when light goes
Speaker 1: from one transparent medium to another, when it passes through
Speaker 1: a barrier, and then what happens to it. So this
Speaker 1: would be like when light travels through air, hits the
Speaker 1: surface of water or air, and it hits a lens.
Speaker 1: That's when you get refraction. Now I'll explain what refraction
Speaker 1: is because it's very important for our discussion. But first
Speaker 1: let's take a quick break. Okay, Before the break, I
Speaker 1: was talking about refraction. Refraction is when light does pass
Speaker 1: from one medium to another and it changes speed. Now
Speaker 1: that might sound weird because everyone knows light is the
Speaker 1: fastest stuff in the universe. It is the speed limit
Speaker 1: of the universe. There is nothing faster than light. In fact,
Speaker 1: we use the speed of light as a constant. The
Speaker 1: famous equation E equals mc squared is referencing the speed
Speaker 1: of light. That's energy equals the mass of something times
Speaker 1: the square of the speed of light. So if it
Speaker 1: is a constant, how can the speed of light change?
Speaker 1: Those two things don't make sense. Well, when we talk
Speaker 1: about the speed of light as a constant, we're referring
Speaker 1: to light traveling through a vacuum, an empty medium, outer space,
Speaker 1: outer space where you've got a true vacuum. But when
Speaker 1: light hits a medium like say an atmosphere or water,
Speaker 1: or the lens of a telescope or glasses, it does
Speaker 1: slow down a little. It changes speed. It can't get
Speaker 1: faster than it can through the vacuum of space. That's
Speaker 1: the as fast as anything can go. But if it
Speaker 1: hits something like trans transparent medium, it will change speed.
Speaker 1: It slows down. Think of it kind of like walking
Speaker 1: in just the open air, like you're going out for
Speaker 1: a stroll, versus trying to walk in a swimming pool.
Speaker 1: You know, when you're in a swing pool and you're
Speaker 1: trying to walk across the pool, you feel the resistance
Speaker 1: of all that water that slows you down, Whereas when
Speaker 1: you're walking through just you know, the room, then all
Speaker 1: you're doing is walking through air. You have much less
Speaker 1: resistance and you're able to go much more quickly. It's
Speaker 1: very similar to that. So when light changes speed as
Speaker 1: it passes into a new medium, it bends. The amount
Speaker 1: of bending or angle of refraction depends upon how much
Speaker 1: slower the light will travel as it moves through the
Speaker 1: new medium. In fact, we call this the refraction index
Speaker 1: when we look at the different transparent media and we
Speaker 1: say all right, well, based upon this difference, will know
Speaker 1: how much of a bend will see in the light.
Speaker 1: So if you've ever seen like a shaft of light
Speaker 1: shining down to a a surface of water, then you're
Speaker 1: looking at like a cross section, like you can see
Speaker 1: both above and below the water. You actually see where
Speaker 1: the bend is there. Or if you want to do
Speaker 1: a really easy one, you get a glass you fill
Speaker 1: it up with water, like maybe to the halfway point.
Speaker 1: Put a straw on that glass, and then you look
Speaker 1: at the glass from the side, and you'll see that
Speaker 1: the straw appears to bend at the point where it
Speaker 1: crosses over into the water. That's because of this refraction
Speaker 1: and this refractive index and the difference between the two,
Speaker 1: and we get that that little bend there. So a
Speaker 1: lens is shaped in such a way as to bend
Speaker 1: light to a specific focal point. If we're thinking of
Speaker 1: it in the terms of rays, right, array coming in
Speaker 1: at the edge of the lens, where it is more narrow,
Speaker 1: is going to be bent a certain way. Array coming
Speaker 1: in through the center of the lens is going to
Speaker 1: go in a certain direction. And then at the very
Speaker 1: bottom of the lens, which is again perhaps more narrow
Speaker 1: we're looking at our typical lens, would then be bent
Speaker 1: in a certain way so that these these different bent
Speaker 1: rays of light will converge at a point where we
Speaker 1: can get, say, an image. This is how we create
Speaker 1: things like corrective lenses for glasses, and bending light is
Speaker 1: really the secret sauce. In most invisibility technologies or cloaking technologies.
Speaker 1: This is pretty easy to understand. There's another way to
Speaker 1: look at this, by the way, and in fact, I
Speaker 1: would argue the other way to look at it makes
Speaker 1: it even easier to understand, which is to think of
Speaker 1: the incoming light as waves and think of the lens
Speaker 1: like let's say that we've got our our regular convex
Speaker 1: lens where it's narrower at the top and bottom and
Speaker 1: thickest in the middle. Right, the wave hitting the top
Speaker 1: and the bottom, those waves are going to be slowed
Speaker 1: down less than the wave that's hinting hitting the center
Speaker 1: of that lens, because the the material is thinner at
Speaker 1: the top and bottom and thicker in the middle. So
Speaker 1: the waves at the top and bottom slow down a
Speaker 1: little bit, but not a lot. The wave in the
Speaker 1: middle slows down the most. And what you get on
Speaker 1: the other side of the lens is this converging wave,
Speaker 1: being the wave is starting to get uh smaller and
Speaker 1: smaller to a focused point because of the the speed
Speaker 1: at which it has traveled through that lens, and it converges,
Speaker 1: and that's where you get your your focal point. That's
Speaker 1: another way to think about it. It becomes really important
Speaker 1: when we start talking about invisibility technologies. All right, something
Speaker 1: else we have to know about light. It's part of
Speaker 1: the electro magnetic spectrum. As I'm sure you're all know,
Speaker 1: the visible of lights just one tiny part of of
Speaker 1: a band of frequencies that make up what we call
Speaker 1: light like light that we can see. That's one tiny
Speaker 1: slice of light. Overall. There's also infrared light, which is
Speaker 1: on one side of the visible spectrum, an ultraviolet light,
Speaker 1: which is on the opposite side. We cannot see infrared
Speaker 1: and ultra violet directly. We can create technologies that let
Speaker 1: us detect this kind of light and then see it
Speaker 1: in the sense of converting that into light that we
Speaker 1: can actually directly perceive. Right, So, if you have infrared goggles,
Speaker 1: you're not actually looking at infrared light. What you're looking
Speaker 1: at is a interpretation of infrared that's been fed into
Speaker 1: technology that gives you light that you can actually see,
Speaker 1: so that things that are really hot appear red, and
Speaker 1: things that are cooler might appear blue, that sort of stuff.
Speaker 1: But the red and blue, that's red and blue. That's
Speaker 1: not infrared. It's just it's been interpreted through the technology. However,
Speaker 1: you took the the goggles off entirely, you wouldn't be
Speaker 1: able to see anything because everything would be dark. That
Speaker 1: kind of thing. It's night vision goggles work on a
Speaker 1: similar idea. So that's where light fits. But then beyond light,
Speaker 1: you've got all sorts of different types of electro magnetism,
Speaker 1: Like you have different flavors of it if you would,
Speaker 1: like you've got radio waves that's on the the longest
Speaker 1: wavelength side of the electromagnetic spectrum, and then on the
Speaker 1: opposite side, on the shortest wavelength side, you have gamma radiation.
Speaker 1: So what determines the nature of this electromagnetism, what determines
Speaker 1: what it can do and what we can use it for,
Speaker 1: is its wavelength or its frequency. The two are related.
Speaker 1: The longer the wavelength, the lower the frequency. The shorter
Speaker 1: the wavelength, the higher the frequency. But here's the thing.
Speaker 1: All of these frequencies are traveling at the same eat.
Speaker 1: That electromagnetic speed is the speed of light, so they're
Speaker 1: all traveling at the same speed. It's just that they
Speaker 1: have different lengths of of waves, right. So radio waves
Speaker 1: are very very very long, gamma waves are very very
Speaker 1: very short. They both travel at the speed of light.
Speaker 1: But it means that the number of waves that pass
Speaker 1: you in a given second are very different for radio
Speaker 1: than it is for gamma, because more of the gamma
Speaker 1: can pass you in the second than the radio waves
Speaker 1: because the length is so much shorter. Well, since visible
Speaker 1: light occupies a range of frequencies, we can encounter some
Speaker 1: challenges when we start to think about ways to manipulate light.
Speaker 1: So there's this effect called chromatic aberration. Sometimes it's called
Speaker 1: chromatic distortion, which be a great name for a band.
Speaker 1: Maybe you just cover social distortion songs. Anyway, Chromatic distortion
Speaker 1: occurs because visible light is made up of a band
Speaker 1: of wave wavelengths of light. You know, red has the
Speaker 1: longest wavelengths invisible light, Violet has the shortest wavelengths, and
Speaker 1: when light hits a refractive surface like a lens, not
Speaker 1: all these wavelengths are going to bend at quite the
Speaker 1: same angle. So you might notice that some parts of
Speaker 1: an image have little borders or fringes of color around them.
Speaker 1: And that's because that wavelength of light, let's say it's red,
Speaker 1: bent at a slightly different angle from the other wavelengths,
Speaker 1: and so you get this kind of halo effect. Now,
Speaker 1: the reason I bring this up is that one of
Speaker 1: the biggest challenges when it comes to creating invisibility technology
Speaker 1: is that the methods we might use could work differently
Speaker 1: with some parts of the visible light spectrum from others,
Speaker 1: and you might end up with the technology that can
Speaker 1: redirect certain parts of the visible spectrum in a specific way,
Speaker 1: but not all of the visible spectrum. And that would
Speaker 1: mean that you would still be able to see the
Speaker 1: cloak or the cloaked object, but it would look kind
Speaker 1: of funny because you wouldn't see all the colors you
Speaker 1: normally would, or it would appear to be a different
Speaker 1: color than what it quote unquote really is. If you
Speaker 1: want to think about another way, imagine that you've got
Speaker 1: a gap that's just wide enough to let visible light
Speaker 1: from green to violet go through. So anything that's green
Speaker 1: to violet and the visible spectrum can pass through this
Speaker 1: tiny little gap. But that would mean that wavelengths that
Speaker 1: were in red, orange, and yellow light because of roy
Speaker 1: g BIV, those wavelengths would bounce off because the gap
Speaker 1: is too small for these wavelengths to pass through it.
Speaker 1: It's it's too narrow. That's kind of what I'm going
Speaker 1: with here, all right, So when we come back, we're
Speaker 1: going to talk about some of the technology is meant
Speaker 1: to make something invisible, and we're gonna start with stealth
Speaker 1: technology after we take this quick break. All right. I'm
Speaker 1: I'm a kid of the seventies and eights, and I
Speaker 1: remember when the stealth bomber was becoming big news. It
Speaker 1: was such a cool science fiction technology. We had heard
Speaker 1: about things like cloaking devices and stuff, but here was
Speaker 1: a plane that could at least what we were told
Speaker 1: passed invisibly for radar systems. So clearly stealth technology, like
Speaker 1: the famous stealth bomber, you know, is not invisible to
Speaker 1: the naked eye. We can see it. It's not like
Speaker 1: it's Wonder Woman's invisible jet here. So we're talking about
Speaker 1: a vehicle that won't show up on radar, but we
Speaker 1: can still see it. That's because radar is operating in
Speaker 1: a different band of frequencies in the electromagnetic spectrum then
Speaker 1: visible light. Right, So if there's something in a direction,
Speaker 1: you've got a radar emitter. The radar emitter is shooting
Speaker 1: out electromagnetic waves, and if that something is there, some
Speaker 1: of those waves are going to hit that something and
Speaker 1: bounce back. So if in addition to the emitter. You
Speaker 1: have a detector that can detect the echoes of these
Speaker 1: electromagnetic waves you've sent out, then you know, hey, there's
Speaker 1: something there, right, And if you actually measure the difference
Speaker 1: in time it took for the waves to go out
Speaker 1: and then bounce back, you know how far away it
Speaker 1: is because you know how fast those electromagnetic waves are traveling.
Speaker 1: So you measure the amount of time it took for
Speaker 1: the waves to go out and bounce back, that tells
Speaker 1: you how far away the object is. You also can
Speaker 1: figure out whether or not the object is moving towards
Speaker 1: you or moving away from you because of the old
Speaker 1: Doppler effect. So if the object is moving away from you,
Speaker 1: the returning waves will actually be longer than what you
Speaker 1: sent out toward it. If it is moving towards you,
Speaker 1: then the returning waves are going to be shorter than
Speaker 1: what you sent out, and the amount of elongation or
Speaker 1: shortening would tell you how quickly this thing is traveling.
Speaker 1: So it's really interesting, like that's that Doppler effect also
Speaker 1: very important to what we're going to talk about in
Speaker 1: just a bit. So let's say that you wanted to
Speaker 1: create an aircraft that could go undetected by radar. What
Speaker 1: do you do well, You probably use a combination of strategies.
Speaker 1: So you might use some materials that can absorb electromagnetic
Speaker 1: waves in the frequencies that are being used by radar,
Speaker 1: so that way, when the wave hits the aircraft, the
Speaker 1: aircraft absorbs that energy and there's not enough to echo
Speaker 1: back to the detector, so it just it just gets
Speaker 1: swallowed up. This would be kind of that super black
Speaker 1: paint we were talking about earlier, where it absorbs most
Speaker 1: of the visible light. In this case, it would be
Speaker 1: absorbing the radar electromagnetic energy. But you probably all start
Speaker 1: going to play a bit with reflection, and you do
Speaker 1: this by designing your aircraft's exterior with these funky angles
Speaker 1: on them, so that if a radar beam does hit
Speaker 1: the aircraft, it gets reflected in an odd direction because
Speaker 1: of that angle that it hits. You know, the angle
Speaker 1: of incidents where the wave hits the aircraft means that
Speaker 1: it's going to get reflected off in a direction where
Speaker 1: hopefully there's no detector, so no one can see that
Speaker 1: there's an aircraft there. This combination of strategies makes it
Speaker 1: very difficult for radar stations to detect stealth aircraft, though
Speaker 1: again the aircraft itself itself is still totally visible to
Speaker 1: us because it's not redirecting or absorbing visible light. It's
Speaker 1: doing it in say the microwave range. Over time, as
Speaker 1: scientists develop new approaches to manipulating, absorbing, and reflecting electromagnetic radiation,
Speaker 1: we would find ways to make objects quote unquote invisible
Speaker 1: to specific kinds of electromagnetic frequencies. But it's a very
Speaker 1: different thing to make an object undetectable from say a
Speaker 1: microwave a mitter, than it is for visible light. Now,
Speaker 1: imagine for a moment that you could redirect light around
Speaker 1: an object, so the light would curve around an object,
Speaker 1: move around to the other side, and then continue on
Speaker 1: as if there were no object for the light to
Speaker 1: interact with at all. So it's not passing through whatever
Speaker 1: is cloaked, it's just going around whatever is quoaked and
Speaker 1: then getting back on track. Then an outside observer would
Speaker 1: not see anything there, right, They just look and it
Speaker 1: would just look like empty space. You'd be looking at
Speaker 1: everything that's on the other side of the object from
Speaker 1: your point of view, and that would be it. That
Speaker 1: would be really cool. Also would be very tricky because
Speaker 1: if you're making all the light curve around the object,
Speaker 1: and I'm saying all the light that's coming curves around it,
Speaker 1: that means inside you wouldn't be able to see anything.
Speaker 1: It would be perfectly dark because all light that's coming
Speaker 1: to you has been redirected. So let's say that it's
Speaker 1: like a small structure and you're inside it. It would
Speaker 1: be completely dark inside that structure because all the incoming
Speaker 1: light has been redirected. You could potentially light something inside
Speaker 1: the structure and thus be able to see And if
Speaker 1: the structure is not allowing light to pass back out,
Speaker 1: then you'd be able to see inside, but you wouldn't
Speaker 1: be able to see the outside world. Nothing in the
Speaker 1: outside world would be visible to you because all that
Speaker 1: light has been redirected. You would have to have a
Speaker 1: way to allow some of the light from the exterior
Speaker 1: world to come through, but still pass enough of the
Speaker 1: light around so that an outside observer would be unaware
Speaker 1: there was something there. That's super duper tricky. It's one
Speaker 1: of the hardest parts of the cloaking device, one of
Speaker 1: not the only so wicked hard to do. As it
Speaker 1: turns out, now we've seen some fun approaches this kind
Speaker 1: of a thing that that do succeed in certain frequencies
Speaker 1: like the microwave range. Uh. And we've also seen some
Speaker 1: fun ways to simulate a cloaking device, but it's not
Speaker 1: actually a cloaking device. For example, a fun one I
Speaker 1: have seen is a screen mounted on say the side
Speaker 1: of a truck, like like a semi truck or something
Speaker 1: along those lines, And you've got a screen on one
Speaker 1: side of display, and on the opposite side of the
Speaker 1: truck you have cameras mounted to capture a live feed
Speaker 1: of whatever is on the other side of the truck,
Speaker 1: and then it feeds that live feed to the screen
Speaker 1: that's mounted on the side, So the truck is totally solid.
Speaker 1: Light is not passing through it or going around it. Instead,
Speaker 1: you're just looking at a video feed on whatever is
Speaker 1: the other side displayed on the truck ruck. And I've
Speaker 1: seen this sort of thing at various events where it's
Speaker 1: just kind of fun, like you can actually see people
Speaker 1: walking on the opposite side of the truck, but it's
Speaker 1: because they're being displayed on this screen. It's not that
Speaker 1: the truck is actually transparent or has magically disappeared, and
Speaker 1: it's a fun effect, or it can be, but it's
Speaker 1: very limited and you know exactly what's happening, right, It's
Speaker 1: not like it's mysterious. Now. I have seen this incorporated
Speaker 1: into costumes in a way that was kind of fun.
Speaker 1: I saw a guy in a zombie costume once where
Speaker 1: he had mounted a tablet inside his costume in the front,
Speaker 1: and he was had a camera mounted on his back
Speaker 1: and it was feeding live video from the camera on
Speaker 1: the back to the tablet so that it looked like
Speaker 1: there was a hole in his torso. Like his torso
Speaker 1: just said this fist shaped hole all the way through,
Speaker 1: and that you can see video from the opposite side
Speaker 1: feeding through on the tablet, which was effective if you're
Speaker 1: looking at him at on. If you're looking at them
Speaker 1: from an angle, it didn't work so well, but it
Speaker 1: was a really clever use of this particular approach. Still
Speaker 1: not really a cloaking device. Right. To get into the
Speaker 1: possibility of actually bending light around an object, we have
Speaker 1: to talk about some really advanced technology, and I'm talking
Speaker 1: about stuff like meta materials and nanotechnology. So first up
Speaker 1: is meta material. What the heck is a meta material?
Speaker 1: I've never met a material I didn't like, No. Essentially,
Speaker 1: a meta material is an artificial material, so you're not
Speaker 1: going to find this in nature. It's not naturally occurring,
Speaker 1: and it's a material that has electromagnetic properties that other
Speaker 1: materials in nature do not have, which can include stuff
Speaker 1: like redirecting electromagnetic waves in a way that just doesn't
Speaker 1: occur in nature, and that can even include light. So
Speaker 1: in the nineteen sixties there was this scientist named Victor
Speaker 1: Veselogue who hypothesized way back in sixty eight that it
Speaker 1: should be possible to have a material that could have
Speaker 1: a negative refractive index. Okay, wait, what does that mean?
Speaker 1: All right, So again, remember we talked about this earlier
Speaker 1: with refraction. When light passes from one medium into another medium,
Speaker 1: the path of that light will change because light traveling
Speaker 1: through the air and then hitting the water will change
Speaker 1: because the speed of light itself changes as it goes
Speaker 1: from medium to medium. So that we all understand, and
Speaker 1: again that's due to the differences in the refractive indices
Speaker 1: of these two medium air has wa refractive index essentially one,
Speaker 1: and clear water would have another like one point three three.
Speaker 1: The bigger the difference between these two indices, the more
Speaker 1: dramatic the angle is going to be. And in the
Speaker 1: natural world, we would describe all these indices as having
Speaker 1: a positive value. But what would happen if you created
Speaker 1: a material that had a negative refractive index, so that
Speaker 1: the light bent in a different way, like it bent
Speaker 1: at a negative angle as opposed to a positive angle.
Speaker 1: Thes A lago suggested that such a material is entirely
Speaker 1: possible without violating the laws of physics, which is a
Speaker 1: good thing because violating those kinds of laws will really
Speaker 1: get into heaps of trouble. But more seriously, admit that
Speaker 1: while such materials don't exist in nature, it should be
Speaker 1: possible to create that kind of material, or at least
Speaker 1: the material itself does not go against the rules of
Speaker 1: the universe, even if we never figured out how to
Speaker 1: make the darned stuff. As a Lagos said, such material
Speaker 1: would behave oddly when exposed to electromagnetic waves, at least
Speaker 1: waves at specific frequencies. Because it would probably be impossible
Speaker 1: to make a material that could interact across the entire
Speaker 1: electro magnetic spectrum in a specific way. You could do
Speaker 1: it in chunks of the electro agnetic spectrum, because again
Speaker 1: that spectrum covers a huge range of wavelengths. So the materials,
Speaker 1: composite parts, the cells that make up this material would
Speaker 1: determine which frequencies in the electromagnetic spectrum would behave differently
Speaker 1: when interacting with this stuff, and specifically those materials, those cells,
Speaker 1: those components would have to be the same size or
Speaker 1: smaller than the wavelengths you were looking to manipulate. So
Speaker 1: as you get further into the electromagnetic spectrum, those components
Speaker 1: have to get tinier and tinier. You get down to
Speaker 1: the microscopic level, and then you blow that out of
Speaker 1: the water and you get even smaller, because if you
Speaker 1: want to get down to the visible spectrum, you have
Speaker 1: to be at the nanoscale. A nanometer is one billionth
Speaker 1: of a meter and at that scale things get wacky.
Speaker 1: As for what you would make this material out of, well,
Speaker 1: that could be conventional stuff. It wouldn't have to be
Speaker 1: anything true the exotic. The material itself could be made
Speaker 1: up of metals or plastics, all sorts of stuff. The
Speaker 1: important part would be the various cells would be the
Speaker 1: correct size, orientation, shape, et cetera, in order to achieve
Speaker 1: whatever goal you set out to make. So that's what
Speaker 1: would affect the electromagnetic waves in different ways more than
Speaker 1: the material itself. It's interesting because we often think of
Speaker 1: creating specific effects by going with a particular chemical composition
Speaker 1: of materials. Right, Like copper is a very good electric conductor,
Speaker 1: for example, so we often think of copper in the
Speaker 1: term in terms of things like wiring. There are other
Speaker 1: materials that are actually better conductors than copper, but they
Speaker 1: also get more rare and more expensive, so copper was
Speaker 1: kind of what we went with. Well, what Vesi Lago
Speaker 1: is saying is that we wouldn't so much be considered
Speaker 1: in the atomic nature of the material as opposed to
Speaker 1: the physical structure of that material, like how small or
Speaker 1: how large it is, what shape it is, and how
Speaker 1: it is arranged geometrically, and what or what's orientation is
Speaker 1: with respect to the incoming electromagnetic radiation. That's what's important,
Speaker 1: the physical actual arrangement of this material, which is really
Speaker 1: interesting way of thinking about things. Now, remember the Doppler
Speaker 1: effect that I mentioned earlier. Vezi Lago said that with
Speaker 1: the right negative refractive index, a material could produce a
Speaker 1: reverse Doppler shift. That's crazy, right, So let's say that
Speaker 1: you had a stealth plane that was coded with this
Speaker 1: kind of stuff, and instead of trying to absorb or
Speaker 1: redirect radar uh energy like the electromagetic waves that a
Speaker 1: is being sent out by radar. Instead, what's doing is
Speaker 1: reversing the Doppler shift. So that way, if this plane
Speaker 1: were approaching you, the reading you would get would indicate
Speaker 1: to you that, oh, there is an object there, but
Speaker 1: it's moving away, Whereas if the plane we're flying away,
Speaker 1: you'd look at and say, oh, there's an object that's
Speaker 1: coming toward us, because the dopplership would be reversed. This
Speaker 1: is hard for me to wrap my head around the
Speaker 1: idea that this material would interact with electromagnetic radiation in
Speaker 1: such a way as to create a result that's counterintuitive.
Speaker 1: It doesn't go the same way as what we're used
Speaker 1: to because again, this material doesn't appear in nature. If
Speaker 1: it did, then we wouldn't find it counterintuitive at all.
Speaker 1: We just say like, oh, that's this material as opposed
Speaker 1: to that material. But because it doesn't appear in nature,
Speaker 1: we don't really think about this stuff. We don't encounter
Speaker 1: it really interesting. However, now, when vessel Lago said all this,
Speaker 1: it was all purely in the hypothetical realm. He said,
Speaker 1: there's no reason why this could not exist, but we
Speaker 1: didn't have a way of making it. Things are different now.
Speaker 1: Starting around the early two thousand's, scientists started to experiment
Speaker 1: in trying to create meta materials, and in fact we're
Speaker 1: starting to be successful, specifically for things like in the
Speaker 1: microwave range of electromagnetic radiation, so that scientists were able
Speaker 1: to create a cloaking device for the microwave range, where
Speaker 1: they were able to put a little cylinder in the
Speaker 1: path of a microwave beam and use this meta material
Speaker 1: stuff to redirect the microwaves so that the microwaves passed
Speaker 1: around the cylinder and continued on as if nothing were there.
Speaker 1: So to the microwave detector, there was nothing in its path. Fascinating,
Speaker 1: but again, doesn't work for the visible light spectrum. Right
Speaker 1: if we were to look, we'd see, okay, the cylinders
Speaker 1: still there, because the cloaking device only effects radiation in
Speaker 1: the microwave range of wavelengths. So to get the visible
Speaker 1: light version of this, we have to reduce the size
Speaker 1: of all those components within the meta materials, because microwaves
Speaker 1: are small, but they're not in the nanoscale small like
Speaker 1: the visible light spectrum is the other side of that.
Speaker 1: Is kind of like when I was talking with chromatic
Speaker 1: aberration earlier. Visible light spectrum that's made up of a
Speaker 1: range of wavelengths. Right, the red wavelengths are longer than
Speaker 1: the violet wavelengths are on the other side of the spectrum.
Speaker 1: So it's hard to find materials and a size and
Speaker 1: orientation that will work with the entire range of visible light,
Speaker 1: which means it's hard to create a cloaking device that
Speaker 1: can work for all light as opposed to just part
Speaker 1: of the spectrum. So even if we get everything down
Speaker 1: to the correct size, we might find it difficult to
Speaker 1: cloak stuff effectively across the entire visible action, which might
Speaker 1: mean that we just end up with very oddly colored stuff. Also,
Speaker 1: we have to remember that when you get down to
Speaker 1: the nano scale, things behave differently like the stuff that
Speaker 1: we're used to at the macro scale at the classic
Speaker 1: scale of physics start to break down when you get
Speaker 1: down to the nano scale. For example, gold gold is gold,
Speaker 1: right like when you look at gold, it's a gold color.
Speaker 1: It's shiny, yellowish gold color. When you break down gold
Speaker 1: down to nanoparticles, It actually, depending on its size, will
Speaker 1: start to reflect light at different wavelengths. So you can
Speaker 1: have gold particles that look red or gold particles that
Speaker 1: look blue, which is weird to say, like, yes, it's gold,
Speaker 1: but it's red. Now, you you're kind of confusing me
Speaker 1: because we've used the same word to describe both the
Speaker 1: color and the material itself. It's like an orange, right,
Speaker 1: if an orange were purple, but we still call it
Speaker 1: it an orange. It probably wrinkle your brain a little bit,
Speaker 1: or at least the wrinkles my brain. I mean, I'm
Speaker 1: a simple person, so that's why it gets to me.
Speaker 1: But the idea of like, at the nano scale, gold
Speaker 1: could be red or blue is weird. It also means
Speaker 1: that when we started getting down there, it may mean, yeah,
Speaker 1: we figured out the the right size and the right
Speaker 1: orientation for all these particles to redirect light. However, once
Speaker 1: we get the elements down to the nano scale, there
Speaker 1: are other properties that emerge that we did not anticipate,
Speaker 1: and that's going to make it even more difficult. So
Speaker 1: there are lots of challenges here. More than that, we
Speaker 1: may just find that we cannot create a practical cloaking
Speaker 1: device that works across the visible spectrum um ever, at
Speaker 1: least not anything that will work better than within specific
Speaker 1: narrow use cases. There have been some demonstrations that in
Speaker 1: uh conditions where there's some light scattering effects, that you
Speaker 1: can actually have a really effective cloaking device, but that
Speaker 1: requires other things to be in place, like fog or
Speaker 1: missed that when you have something that's causing light to scatter,
Speaker 1: it becomes easier to redirect certain light and make it
Speaker 1: difficult to see something. You can effectively have an invisible
Speaker 1: object in the space, but then you're also talking about
Speaker 1: these other things that are impacting that You're already impacting
Speaker 1: visibility at that point anyway, So it's got very limited utility.
Speaker 1: Still really fascinating, and I'm not saying we're never going
Speaker 1: to get there. I would never say that, because people
Speaker 1: way way smarter than I am or working on these
Speaker 1: kinds of technologies. Whether there's ever a practical use for it,
Speaker 1: that's another question, because while you might be able to
Speaker 1: create something that is invisible to the naked eye, you
Speaker 1: would still end up having to factor in things like
Speaker 1: radio waves, microwaves, all sorts of stuff, because again, not
Speaker 1: all wavelengths are the same, and if it cannot manipulate
Speaker 1: or warp these these incoming electromagnetic waves equally across the spectrum,
Speaker 1: then it's going to be detectable by something. And also
Speaker 1: you have to still fix that issue that if you
Speaker 1: don't have a way of allowing at least some of
Speaker 1: that light to pass into the cloaked area, it will
Speaker 1: be pitch black inside the cloak because no light is
Speaker 1: coming in. It's all being redirected around it. There are
Speaker 1: other elements that you have to worry about. Two. I
Speaker 1: didn't even get into things like phase shifting, largely because
Speaker 1: I only have a limited understanding of it, and I
Speaker 1: quickly get out of my element. And while I could
Speaker 1: attempt to try and go down road, I would probably
Speaker 1: steer us all the wrong way, and then I'd get
Speaker 1: a lot of messages calling me out on that. And
Speaker 1: rightfully so, even as it stands, I worry that I've
Speaker 1: oversimplified things to a point where I'm being misleading. It
Speaker 1: is difficult to break this down to a level that
Speaker 1: I am comfortable communicating without feeling like, oh, I'm just
Speaker 1: saying things, but I don't understand what I'm talking about
Speaker 1: and that really comes down to the fact that I
Speaker 1: haven't taken a science class in why like almost thirty years,
Speaker 1: so I'm working on a lot of old brain cells
Speaker 1: that are are grumpy that I've called on them for
Speaker 1: this episode. Still fascinating stuff. And the demonstrations I have
Speaker 1: seen even of the limited quote unquote invisibility where it's
Speaker 1: not the visible spectrum but it's other ranges of the
Speaker 1: electromagnic spectrum, They're amazing. And the idea that we can
Speaker 1: create materials that have counterintuitive reactions to electromagnetic radiation is
Speaker 1: incredibly fascinating. And there are some really cool applications beyond
Speaker 1: the fantasy science fiction concept of invisibility, like completely transforming optics,
Speaker 1: so that you could have, at least on one level,
Speaker 1: a much simpler approach to optics where you have incredible effects,
Speaker 1: but you've really reduced the complexity of the overall material,
Speaker 1: the overall UH tool, for example, like a telescope, and
Speaker 1: you were able to do that by using specific meta
Speaker 1: materials like that, to me is truly amazing stuff. Being
Speaker 1: able to reduce complexity and points of failure by engineering
Speaker 1: material that just more effectively redirects or interacts with electromagnetic radiation.
Speaker 1: That's mind blowing. Like to me, that is science fiction,
Speaker 1: and yet it's stuff that's unfolding right now, and that's
Speaker 1: why I think it is so cool. All Right, I'm
Speaker 1: done geeking out about invisibility now, not really done, but
Speaker 1: I'm done talking about it. So if you have suggestions
Speaker 1: for topics I should cover. I've got a planned episode
Speaker 1: coming up where we're gonna talk about the history of
Speaker 1: spy balloons because obviously that's been in the news a
Speaker 1: lot lately, so I want to talk about that because
Speaker 1: that history stretches way back, y'all, and I want to
Speaker 1: talk about like the early use and then the the
Speaker 1: evolution of the technology and the use of such balloons
Speaker 1: and look forward to that in the near future. If
Speaker 1: you have other topics you would like me to tackle,
Speaker 1: let me know. You can reach out on Twitter. The
Speaker 1: handle for the show is tech Stuff hs W, or
Speaker 1: you can download the I Heart radio app. It's breed
Speaker 1: to download and use. You can navigate over to tech
Speaker 1: Stuff by putting that into the little search field. It
Speaker 1: will take your right to the page. You'll see there's
Speaker 1: a little microphone icon there. Click on that you can
Speaker 1: leave a voice message up to thirty seconds in length.
Speaker 1: Let me know what you'd like to hear in the future,
Speaker 1: and I'll talk to you again really soon. Yeah. Text
Speaker 1: Stuff is an I Heart Radio production. For more podcasts
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