July 16, 2014 • 40 mins
What are metamaterials and what gives them their nifty properties? We look at materials science and how metamaterials might transform our world.
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Episode Transcript
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Speaker 1 (00:04):
Get in touch with technology with text stuff from how
stuff works dot Com say they're and welcome to text Stuff.
I'm Jonathan Strickland and I'm Lauren, And uh, this test,
we're not doing a listener request, although I would imagine
a lot of our listeners have heard about the subject
we're going to be talking about today. But before we
(00:25):
get into it, Lauren, what is your favorite implementation of
the concept of invisibility in FICTIONUS? Uh, probably the Ronnie
Lank cloaking device, Yeah, which the Klingon's managed to get
their hands on because I was to get the Bird
of Prey from uh well, they both had Bird of
(00:45):
Praise that could cloak, and the Star Trek University. Eventually
the Federation picked it up as well. We could really
really get into a full thing of us just talking
about Star Trek and cloaking devices as it turns out. Yeah, No,
that's a cool, cool implementation. Another one, of course, the
Predator being able to have that chameleon likability or I guess,
I guess the halo armor. Yeah, there's of course the
(01:08):
the Harry Potter invisibility. Yeah, the hay cloak with the
Marauders invisibility cloaks. So yeah, we've we've got all these
ideas about invisibility. It's of course been a popular concept
in fiction, whether it's fantasy or science fiction. In the
world of science fiction, of course, we have to try
and come up with a way of how would this work,
(01:29):
how would we manage to make something invisible? And well,
some people feel more obligated to do that than others. Well, yeah,
because some people would argue that if you don't do it,
you might as well call it science fantasy rather than
science fiction. But the the concept usually boils down to
the idea of somehow manipulating light so that bends around
an object and then continues on as if the object
(01:51):
were not there. So from an outsider's perspective, it's just
you know, emptiness or or whatever. It's whatever, see the
starf behind you or the wallopping willow or whatever. It excellent,
really well done. I was wondering where you're going to
go with the Harry Potter one exactly. So the interesting
thing is that there are people who are really working
(02:12):
on this technology. You guys out there have probably heard
about variations on real world cloaking devices, and you may wonder, well,
how is this even possibly attempted, and there are a
lot of different approaches, but one emerging field that we
wanted to talk about is meta materials. Right, because with
normal materials, perhaps obviously, normal materials do not bend light
(02:35):
around them so that you can see what's on the
other side when they're solid and opaque materials. Yeah, yeah, exactly,
Even a even a transparent window is reflecting some light
back to you. Right. The idea of a meta material,
at least in this particular implementation, because there's lots of
different potential ways to use meta materials, is to bend
(02:56):
electromagnetic radiation, in this case visible light around it so
that we wouldn't see it. Now, we're not there yet,
by the way, spoiler alert, Yes, um, we are working
slowly towards it. But let's put down a good solid
definition of meta materials to kind of start the conversation off. Okay, so,
first thing to keep in mind their artificial These are
(03:16):
these are materials that are man made, and they are
very different from natural materials because the properties that you
would find in any natural material are largely dependent upon
its chemical composition. So, for example, a bar of gold,
a bar of gold has the weight, the color, the density,
(03:37):
it has all of these things because of the nature
of the atoms of gold. Right. That's if it were
a different material, it would have very different properties, even
if you had it at the same physical dimensions, right
and so, And even though okay, a bar of gold
is also a man made object, you're rarely going to
pull a large chunk of gold like that right straight
(03:58):
out of the ground having minecraft or something without it
having some kind of impurities that you would have to
melt out or whatever it is that you do. But
basically it's all chemical exactly. Now, manty materials they get
their properties not just from the kind of atoms or
molecules that make up that mety material. In fact, the
chemical composition doesn't really ultimately matters they structure exactly. It's
(04:24):
it's how that material is physically constructed. And when we
say physical structure, we're not talking about something you can
see on the macro level. We're talking this is micro
to nano exactly, to the point where it's so small
that an optical microscope would not be able to show
you what that structure is. And a lot of this
was sort of theoretical. We'll talk about the history of
(04:46):
it until relatively recently, we've just now started to get
too sophisticated manufacturing processes that allow us to build these
super tiny structures that will affect uh well, that will
interact with electromagnetic radiation and interesting ways. Right. It's sort
of similar to the way that we've talked about nanostructures
(05:08):
having different effects on the world around them, then we
would normally be able to observe larger structures. Meta materials
are similar and a lot of them will interact specifically
with electromagnetic radiation in very interesting ways. So if you
look at electromagnetic radiation, if you were to to just
be able to stop the whole universe and just look
(05:31):
at a specific wave of electromagnetic radiation and be able
to break that apart, conceptually, you'd be able to see
that there are two major components of it, which are
electric fields and magnetic fields. Um, there's also the vector,
which is the wave's magnitude and direction. So all three
of these things together determine how they interact with any
(05:54):
given I reject exactly, and so conventional material usually only
in acts with the electric fields. Usually there are some
that interact with magnetic fields, but Generally speaking, the electric
fields are what are interacting with conventional material Many materials
can also interact with the magnetic fields, which increases the
number of ways it can interact with any given electromagnetic radiation.
(06:19):
Keep in mind, visible light is electromagnetic radiation. It's part
of that spectrum. It's a very narrow part of that spectrum,
which also includes things like ultraviolet light and infrared light,
but also microwaves and radio waves. Um. So this is
the stuff that would, at least in theory, if we
(06:39):
were able to build the right kinds of structures, allow
us to create an invisibility cloak for real zes or
at least some sort of of physical object that light
would bend around so you would not be able to
see it. And right now we only have invisibility cloaks
that bend microwaves around. The implementations tend to be very
(07:01):
specific to very narrow bands in that spectrum, right and
we'll talk about it. This has to do with the
specific micro and nanostructures of these objects, which we'll get
into in a moment um. But while we're talking about waves,
electromagnetic waves are not the only ones that hypothetically these
materials can interact with right, absolutely, anything that travels in
(07:23):
wave form can in theory be uh something that interacts
in a different way with a meta material. So seismic waves, earthquakes,
that those it travels in waves, just like you know,
it's hard for us to imagine in a way things
like electromagnetic radiation because we can't directly see those waves. Um,
(07:43):
we also can't well, I guess we can see earthquakes,
or we can see the effective earthquakes, right, we can
certainly feel them, certainly, So those those seismic waves that
travel through the ground, you could in theory create a
meta material that allows that stuff to just passed through
it as if it weren't it wasn't there, and then
imagine making a building out of that stuff. It wouldn't
(08:05):
even sway when the earthquake moves through. The earthquake would
just pass through it as if it weren't there. It
would just redirect. Yeah, it's the same thing with sound waves.
You could build I mean, I'm I'm picturing our sound
studio right now without all of this albeit lovely foam
that that Noll has put up on our walls. Instead
of that, the walls themselves could just be made of
(08:26):
a material that redirects the sound waves. They could either
absorb it or because again it all depends upon the
physical structure of the material itself. If you were able
to do that, you could have a perfectly soundproofed room,
so you would never have to worry about any sort
of bleed out either going out of the room or
coming into the room. And we would really like that
(08:46):
because often we have to stop when there's a siren
or a drag race or something going on outside, so
that you guys, I mean, I'm sure a couple of
them have snuck through anyway, but we try to limit
them also at will. Waves like ocean waves, those are
another form that I've seen. I've seen the Navy looking
(09:07):
into a strategy where they would have a special meta
material on the outside of the whole of ships to
make them more efficient in moving through the water, exactly
releasing all that drags so that you don't have to
worry about that. It doesn't have to do as much
work to move a huge vessel through the water because
you have redirected the waves as if you're not there. Also,
(09:29):
you could in theory, reduce the wake of a vehicle
moving through the water, so that the ocean itself does
not reveal the fact that an enormous like aircraft carrier
just bustled through. You wouldn't have a wake, it would
This to me is hard to imagine. It's hard for
me to imagine. Yeah, going all, you know, Scutty said
(09:54):
you cannot break the laws of physics, and I think
I think it was a little shortsighted. Actually, I think
mento materials kind of prove them wrong. But I mean,
clearly we're still working within the laws of physics. It's
just we're expanding our our knowledge of how they how
they work. We're just tweaking them a little bit, you know,
kind of you know, just a little thumb of the
nose at the laws of physics. So, alright, what is
(10:17):
actually going on here? How you know, we've talked about
what they are and what they do in general, and
we've talked about this structure issue. But let's let's get
down into it. Yeah, So, if you were able to
shrink down to a teeny tiny size and observe this
material on the nano scale, what you would notice is
that the actual physical structure of that material would be
(10:39):
made up of repeated patterns. They would be kind of
like a repeated scaffolding in a way. And think, again,
this is on the nano scale. You to to us
on the macro scale, it would just look like stuff.
Whatever it happened to be made out of. We went
notice that structure because it's far too too tiny for
us to see. But you would see these repeated patterns,
(11:00):
and those repeated patterns would be specific to whatever wave
it was supposed to interact with. Because here's the thing.
For meta materials to be effective, generally speaking, those structures
need to be smaller than whatever the wavelength is of
the whatever it's going to interact with. Right. This is
why we've had better success with microwaves than anything else,
(11:23):
because microwaves are very long wavelength as well, I mean
compared to light. Absolutely. If for red's the same way
and for red is a longer wavelength and say red, Yeah,
so you run into a building problem, just just a
structural issue here. Exactly how do you build something tiny
enough to interact with these very tiny wavelengths? Yeah, so
(11:45):
in order for you to have something that would be
able to shield an object from visible light, you would
have to make uh structures with such precision that those
repeating patterns would be just teeny teeny tiny, like yeah,
as building blocks would have to be like no bigger
than ten to twenty nanometers. Yeah, that's really super small.
(12:05):
And we've managed to do that kind of thing with microprocessors,
but we're talking about expanding that out potentially to a
three dimensional object. Ultimately, when you're looking at microprocessors, you're
really talking about two dimensions. You're talking about the height
and the width. There's no real Yeah, it's to the
point where you might as well say it's two dimensional.
So when you're talking about three dimensional object and building
(12:28):
that outward volumetrically, especially to cover say a car or yeah,
oh yeah, or an aircraft carrier or whatever. Obviously the
military carrier whatever, the military applications for this are obvious, right,
I mean any kind of cloaking device. So yeah, being
able to manufacture that out in a way that it
(12:49):
has a practical effect is an enormous undertaking. It's something
that is, uh, we're years beyond that, like or no,
that's years beyond us, I should say we we and
it not close together. As my point, we're kind of
shouting at each other exactly through the future exactly, so
(13:09):
although we can't see them because when they're in the
future in two they're invisible. But uh yeah, that's the
thing is that you have to have these super super small,
small small structures. And not only that, but visible light
takes up a spectrum. You know, we say the visible spectrum,
and you know the easy way of saying that as
the Roy G. Biv Right, You've got from red on
one end to violet on the other end, and that
(13:30):
and everything in between. And that's what makes a visible
light for us. Well, in order to be able to
shield something from visible light, you would have to somehow
engineer a meta material that would be effective for that
entire range of those wavelengths. That's really tricky. It's one
thing to design a meta material that works for a
(13:51):
narrow range of wavelengths. That is, it's I hesitate to
use the word easier. It's more realistic than effect creating
a material that would be effective across an entire spectrum
of wavelengths. So it may be that we never get
to a point where, using meta materials we create a
(14:12):
cloaking device that's effective for visible light. That doesn't mean
we won't create cloaking devices. We may do it through
a totally different technology, or we may have cloaking devices
that are cloaking devices for specific wavelengths like microwaves, because
radar uses microwaves. Right, So, a stealth bomber that has
meta material surfaces which means that the radar waves will
(14:36):
go straight through it and not bounce back, you wouldn't
have to have those super funky uh the panels that
are all at weird angles. Yeah, that whole episode right right.
The surface of stealth bombers right now operate by redirecting
those waves exactly. It's kind of like the idea of
just uh, deflecting the wave to some other direction ap
(15:00):
from the receiving station. Right. So, as long as the
receiving station never gets the waves back, it doesn't know
that there's an object. So you can you could go
on and make those things more aerodynamic at that point, yeah,
you could. You could completely redesign the self the weird
bulky looking thing. Yeah, I mean sure they were ridiculously
expensive and inefficient ultimately, but hey, they look cool. I
(15:24):
also like the Deloreans, so same. I mean, Deloreans show
up on radar like crazy, but that's that's that's another episode. Now,
there are different types of meta materials. There's there are
different ways of building meta materials to interact with various
types of wave links. So I'm going to go ahead
(15:45):
and preface this part of the podcast by saying, neither
of us are physicists, and electromagnetic radiation is a difficult
topic to wrap your head around when you haven't had
that as as your continual background for say thirty years. Yeah.
So if there are any physicists out there who cringe
(16:06):
as we start to oversimplify what's happening, I apologize to you. Now.
I am doing the best of my ability to explain
what's going on. Yes, and if we get anything wrong,
please do be gentle with us, but let us know, Yes,
please do, because then we can always do a follow
up and say, you know what, we were doing this
based on our understanding, and as it turns out, our
(16:26):
understanding was flawed, and here's how it really works. We
appreciate that. Yes, please be gentle. Alright, So starting off,
we have the electro magnetic band gap meta materials or
also known as e b M meta materials or just
a b M, because that's what the m stands for
So these manipulate light propagation, and they are either made
(16:47):
from left handed materials or photonic crystals left handed materials.
That means they're more creative, it means they're sinister. So
when you go to the old French being a left hander,
I consider myself sinister. Now, left handedness and electromagnetic radiation
is um a very particular thing and you've got to
(17:07):
be careful on how you define it. So with electromagnetic radiation,
like we said earlier, you've got the electric field, the
magnetic field, and the wave vector, which is that magnitude
and direction combo. Right, So you also have physical material.
So any given physical material has a couple of different features,
one called permitivity and one called permeability, and those are
(17:29):
the ways in which it's going to interact with any
given wavelength of electromagnetic radiation. Right, Yeah, Because your permitivity
is how it interacts with electric fields. Your permeability is
how it interacts with magnetic fields. And a positive number
essentially says that it has this kind of interaction. But
here's the thing you can actually have. You can create
(17:51):
a material that has negative permitivity and negative permeability. You
won't find it in the nature, or at least we
haven't found anything in nature so far that has both
negative permeability and permitivity simultaneously. We have made stuff that does,
and that stuff is called left handed yes and h.
(18:11):
So it's really interesting concept that you are able to
create something that has this negative permitivity and permeability. What
it ultimately means is that you could create a material
that resists waves as they impact that material. So imagine
creating a military vehicle out of this stuff and there's
(18:34):
an electromagnetic burst. This thing would actually effectively the material
itself would push back against that oncoming electromagnetic wave, leaving
the vehicle fine. So you could imagine that being really
effective for something like an electromagnetic pulse weapon that wipes
out electronics. Otherwise, if you're if you have it shielded
(18:56):
with this stuff, it's like the ultimate Faraday cage. Yeah,
it's like a field almost, but it's because of again
the physical structure of the structure of the material. Yeah,
there's there's no energy thing going on here. It has
nothing to do like you don't have to turn off,
switch off exactly. It's just the way the stuff is
(19:17):
physically built. It's it's unbelievable to me. It's amazing to
me that just by uh, specifically designing the structure, you
can dictate how electromagnetic radiation is going to interact with something.
And now there's also single negative meta materials, which would
have one of those two things, primitivity or permeability, be negative,
(19:41):
but the other one would be positive. Then you have
natural materials that have like the double positive, which means
the permitivity and permit permeability are both positive. You can
make meta materials that have that same stuff. Uh, I mean,
it all depends on what you want the meta material
to do obviously. Uh. Then there are others that get
restively more difficult for me to describe. So I'm not
(20:03):
gonna try because I know at that point I would
just be giving misinformation. But uh, that's the basic ideas,
the the idea of interacting with either the electric field
or the magnetic field or both in a way that's
different from your general natural materials out there. So this
all sounds like incredible science fiction technology to me. This
(20:26):
is all probably really recent research, right, Well, how about
late nineteenth century is that still recent? I mean, overall
from a geological time scale, it's like no time at
all has passed, but for for humans. Yeah, this this
is actually the whole concept is built upon observations that
(20:47):
were starting to come out of the scientific world in
the late nineteenth century. Back in a scientist named Jagaudie
chunder Bows experimented with microwaves and twisted structures that today
we would call artificial chirals. Chiral, by the way, is
essentially an asymmetric shape. It's one that if you were
(21:08):
to superimpose a reverse of its image, it would not
fit onto itself. Um. He found that by introducing randomly
oriented wire helisses as in the plural of helix uh
in a host medium, he could create a microwave lens. Essentially,
he was bombarding stuff with microwaves and he had these
(21:28):
little wire helix structures embedded into that material, and then
he would move the little helix helis sees around, changing
their orientation, changing their their layout, and he discovered that
that was changing the the effect of those microwaves. He
could focus it exactly, so he's like, huh, something to
(21:50):
do with the physical structure is affecting the way the
microwaves are behaving with this material, and that was the
very beginning. Some say, because there are people who argue
about whether or not this is in fact the origin.
But by the nineteen sixties you had scientists hypothesizing that
if we were in fact able to build stuff with
(22:12):
incredible nano precision, we could do so and make it
so that it behaves in a specific way when introduced
to electromagnetic radiation. There wasn't any way we could actually
do it at that time. Yeah, we wouldn't actually get
into that kind of production technology until the nineteen nineties. Yeah,
And in fact, really it wasn't until the two thousands
(22:33):
that you started seeing the first real forays into the
microwave world, where we were trying to uh specifically create
a meta material that would allow microwaves to pass straight
through it as if nothing were there at all, and
kind of around it. But yeah, kind of around it. Yeah.
When I say through it, over it, I guess technically, yeah,
(22:54):
imagine that the light like think of it almost like water,
you know how water. If you put a stone in
an in flowing water, the water will just flow around
the stone and then continue on as if nothing were there.
It's the same sort of things. In this case, we're
talking about light. It actually bends around the object and
then continues on not to us, it's as if light
is just passing straight through it, right, That's that's an
(23:16):
optical illusion. So if we were able to see in microwaves,
we would not see that object. It would just be
as if there was nothing there at all. So that was,
you know, kind of the beginning of it. But as
far as where we are now, we're really seeing lots
of effort going into making this technology more sophisticated. Uh,
(23:37):
And we're able to create much more precise meta materials
than we ever have been before. Oh yeah, A lot
of that has to do with three D printing. Talk
about that a lot on this show. We do. Uh.
For example, that microwave invisibility click that we were that
we've been talking about involved printing wires and patterns on
too circuit boards in order to create this this shield. Yeah, yeah,
(23:59):
that's pretty cool. So this whole microwave shield thing, it's
obviously the best example because those are the ones that
have had the most experimentation, the than the greatest success
rate so far. Again, it tends to be narrow bands
of the spectrum. It's not like it will affect every
wave length, but it has shown that this could be
(24:22):
possibly used for stealth technology, like or if you want
to turn it on its head, you could actually make
more effective antennas using meta materials. Right, instead of it
being something that that the waves passed through, it could
be something that is channeling those waves more effectively, either
to transmit or to receive, whether it's microwaves or whatever.
(24:45):
In fact, I've even seen talk about optical antenna's, So
it would be something in the light range, not necessarily
visible light, but in the light range that would be
really effective at transmitting and receiving because the meta materials
themselves were channel ling that radiation in a more effective
manner um. Again, we're getting to a point now where
(25:06):
I'm like, I understand the application, Understanding the mechanism is
getting more and more complex. And then there's the idea
of creating like an amazing microscope or telescope using meta
materials to create super lenses. So here's here's the thing.
When we talk about the nanoscale, and we talked about
(25:28):
not being able to see something with an optical microscope,
the main reason we talk about that is that you're
talking about trying to look at things that are on
a scale that's smaller than a light wavelength. So here's
the weird part in theory. You could use meta materials
that have a negative refraction index refraction. When when you're
(25:52):
talking about lenses, there's a thing called the diffraction limit,
and it's one of those things that like, the better
or lenses, the less problem you have with diffraction, but
ultimately you're going to run into it at some point
or another. The menty materials can start to make that
less and less of a factor. So as you have
this negative refraction index, which would allow you to look
(26:15):
at stuff that normally would be too small for you
to see whether that is a distant star. So you're
talking about a telescope in that case, or something on
the nanoscale, so you're talking about a microscope on that case.
And the the idea here is that, Okay, lenses focus
light by bending it right, UM, and the refraction index
measures how much a given material will bend the light
(26:38):
passing through it. Uh, you know, the way that an
object will look different when you view it through water
or through a wine glass or something like that. UM
and a negative refractive index means that the material is
bending light the wrong way, which could allow for this
very precise fine focus. Um, but it kind of goes
(27:00):
against just again your common sense of how things work, right,
because you're saying, oh, well, this just does it the
opposite way. But but that's that's the thing at all.
That's like saying if I jumped into water, I would
get more dry. Like it's something that goes so against
what are common experiences. It's hard, at least for me
(27:21):
to imagine it. It's difficult for me to have a
concept of how that works. But it does. But it does,
and it could be useful for a number of technologies
because a number of technologies in fact, to use optics,
how about fiber optic cables or optical discs like DVDs.
H that this kind of research could lead to huge
(27:42):
improvements in a DVD's data capacity or in fiber optic
cable transmission speed or power consumption. So one of the
things that I talked about on a forward Thinking episode
an upcoming forward thinking episode spoiler alert, folks, is the
whole field of photonics. The idea of creating electronic components
(28:03):
that are based on light rather than on electricity. So
the thing about photonics is that they tend that they're
incredibly fast, Like you can move a lot of data
at the speed of light. So when I say fast,
I'm not just talking about transmission speed, because really we're
talking at this point transmission speeds that are close to
the speed of light. I'm talking about how much information
(28:25):
you can move through that channel at once. So throughput
is probably a better word than speed. But the problem is,
especially when you get into things like quantum computers, you're
limited by how far you can you can extend these systems.
You would not be able to create at this moment
with our technology right now, a an internet based on
(28:47):
quantum computers. It wouldn't reach far enough for you to
be able to do that. I think thirty kilometers is
about the limit that you can get. And while we
could in theory build out a network that has a
density for that, when you're getting to places that are
you know, further out, Yeah, it's make working from Antarctica
(29:08):
really difficult, right but by using meta materials and improving
fiber optic technology, we might be able to address some
of those issues and be able to extend that kind
of of utility. Further, so then we are able to
have these massive nate you know, networks of fiber optics
that don't have any data loss issues or at least
(29:30):
fewer data loss issues, and be able to put everyone
on this incredible speed, and then we don't have to
worry about the whole net neutrality thing anymore. I'm dreaming,
I know, but still it's pretty cool. It's a beautiful dream.
And besides fiber optics and DVDs, we could also see
this helping improve technologies like ultrasonic technologies, anything that again
(29:54):
involves waves, so sound ultrasonic obviously the whole sound profing idea,
who stick shielding that kind of thing. Also, uh, you
know solar panels again you want to redirect that light.
So these are really cool potential applications of meta materials,
assuming that we get to a point where we can
(30:14):
produce them. Yeah, right, um, they could be the next
evolution of ultra light objects. We were just talking about
that in our camping episode. I mean, although this would
probably be a little bit of the price point of
many people are looking for hobbyist camping for a mere
three million dollars. Uh m, I t and the Lawrence
(30:34):
Livermore National Laboratory are working on three D printing stuff
that has super low density and super high stiffness and strength. Um.
For example, they can print these tiny lattices of polymers
and then coat those lattices with thin films of metal materials,
metal or ceramics or something like that, and then melt
out the original polymer, leaving these little, tiny, bitty hollow
(30:58):
tubes with walls you know, only like fifty to animeters thick,
that are incredibly strong, like able to bear loads that
are at least a hundred and sixty thousand times their
own weight. Again, hard to conceive, It's hard for me
to imagine. Meanwhile, scientists at the University of Southampton have
been working with materials that will adhere to a surface
(31:22):
when that material is exposed to light. What. Yeah, So
imagine that you've got a wall, maybe it's made out
usually you're talking about a dielectric wall, so something that
can conduct electricity. So like, let's say that it's a
stainless steel wall or some sort um, and you put
this thing whatever it happens to be against that wall,
and as long as it is being stimulated by light,
(31:44):
it sticks there, and if you were to take away
the light source, it would no longer stick there. And
it's because it's a meta material that has these little
vibrating electrons sites that would interact with electrons that are
on the surface of the wall. It's health so it's
an electron electron interaction that doesn't involve repulsion. And that's
(32:05):
as much as I can tell you, folks, because I mean,
once I started looking into it more, I was like, Okay,
I'm gonna have to take a full course in physics
for me to really understand what's going on on a
physical level. But the cool part is that this could
potentially become a new way of developing brand new technologies
that we can't even really conceive right now. Yeah, that's
(32:27):
kind of a new fundamental force. Yeah, it's essentially the
discovering that wait a minute, there's something else that that
can happen with under these specific circumstances that we didn't
know about, and it is a fundamental force, which is incredible.
I mean it, this is an amazing scientific discovery. So
even if there's never like a practical application, just knowing
(32:47):
that this is another way that our universe works is
a valuable lesson. Oh of course. Um. Meanwhile, over at
the University of Texas at Austin, they've been working on
creating these meta material mirrors that are only foim, they're
thick that can double the frequency of infrared radiation that
hits it. Okay, So if the incoming radiation has just,
for example, a wavelength of eight micrometers um, the outgoing
(33:11):
reflection will have a wavelength of for micrometers um, which
is a pretty awesome feature. But the researchers are also
saying that they can possibly fine tune the structure to
adjust the reflection to other desired wavelengths um. The mirror
is made of a bunch of wacky stuff, including indium, gallium, arsenic, aluminum,
(33:33):
and gold. But that's a little bit beside the point
I just found. I was like, arsenic is in there.
That's cool, and how I deal with That's what? That all? Right? Um?
But but so you know, being able to convert the
frequency of wavelengths at will would be incredibly awesome for
a bunch of different optical purposes, like miniaturizing laser systems
or improving optic space sensory tech. Yeah. Yeah, In fact,
(33:57):
I've I've seen a lot about meta materials used to
help create these manature laser systems, and you might think, well,
what's that good for. We'll go back to that photonics
discussion we had just a moment ago that would be necessary.
If you want to have a microchip that is working
under photonics and not just electricity, then you have to
have these lasers that generate the light and by manatorizing it,
(34:18):
that's what makes it possible. Otherwise, you know your components
are going to be larger, which means your devices have
to be larger in order to take advantage of that
photonics technology. So this is really promising. Then you have
this This was again one of those things where I
read it and I thought, what some folks at Northwestern University,
some scientists have been working on a material that would
(34:39):
act the opposite way you would expect it to based
upon our experience with the world around us. So imagine
you've got a cushion, and when you sit on that cushion,
instead of sinking down into the cushion as you would
with any normal cushion, the cushion pushes back against you
and actually rises up. Or imagine that you've got some
sort of silly putty. But instead of when you pull
(35:01):
on the silly putty and it stretches way out, it
starts to compress as you pull on it. In other words,
it sounds like we're talking about Harry Potter again. It
is physically behaving the opposite of what it should if
it were just a decent, law abiding material. And here's
the crazy thing is that they're scientists who are working
on creating material that does this stuff. Essentially, when you
(35:24):
when you pull it, it compresses and when you compress
it it expands. And they said that the way they
did it because normally, if you made a material like
this that could do this, it would be very unstable
and it would collapse in on a more stable, uh structure.
That what they did was they started by creating a
stable structure that already did this, so when it collapses,
(35:47):
it's collapsing into the the base form of this so
that when you pull on it, it compresses. And uh.
They explained the concept because again they're they're working on this.
It's not like they have big old piles of this
flubber like stuff out there. They're working on it, and
it's very much in the hypothetical phase. They described it
(36:07):
by by describing, uh, four atoms that are in a
horizontal line and uh, and trying to pull those atoms
apart would would cause them to compress closer together. That
illustration didn't help me at all. But that's not due
to them. That's because I'm dense. So I'm not blaming
(36:28):
it on you, Northwestern University. I'm blaming it upon my
own limitations. But I think, what again, just by making
this material a specific structure, it has these very different properties. Yeah,
I think that part of this is so hard to
wrap our minds around because it's i mean, not only
is it breaking the laws of physics kind of sort
(36:49):
of um, but also because it's also new. Um that
there was a market research company called BCC Research that
just this year estimated that the global market for mety
materials is going to expand from like two eighty nine
million dollars in to some one point two billion by nineteen.
(37:10):
So because the future is bright, it's hypothetically picking up
and it's it's the future is not just bright, it's invisible.
But but to be to be fair, to be fair,
this this proves, like you say, two million dollars, which,
don't get us wrong, that's a lot of money. We're
not saying it's a little money. If you think it's
a little money, give us two million dollars. But it's
(37:33):
a drop in the bucket compared to other industries. It's
really proving that mety materials are in their infancy. So yeah,
well it's it's incredible to think of the sort of
applications that could potentially come out of this. I mean,
imagine a city that's earthquake proof. That or a bridge
that really is earthquake proof that the earth is shaking
(37:55):
around it and the bridge is just fine. That's it's
it's it blows my mind. It's incredible. I would like
that future. It would be an awesome future, be fantastic.
So we're really excited to see where meta materials go.
We're really excited that again, this is properties that are
just based upon the physical structure of that material, has
(38:16):
nothing to do with like, hey, we we managed to
make this new you know, stuff that is really unstable
and decays almost immediately. So that's unfortunate, but look at
the cool thing it does for the split second it exists.
That's not what we're talking about. This is stuff that
has permanency because again it's just the physical structure at
that nano level that gives it that ability. Wow. All right, Well,
(38:40):
now that we have melted our brains and hopefully stimulated
your brains, I would like to invite all of you
guys to suggest any topics you might want to hear
about in the future. Maybe you said that was really interesting,
Can we talk about something like really simple? Now? Maybe
maybe the technology often Kitten's kitten technology. Obviously that would
(39:01):
involve a deep discussion about YouTube. Just let us know
if you have any suggestions, or you have questions, or again,
maybe we have covered something but perhaps are limited explanations.
You feel we're we're not rich enough, and you have
a way of putting it into words that we need
to share with our listeners. Let us know. Sleace us
(39:21):
an email. Our address is tex Stuff at how stuff
works dot com. Or if the message is really short,
like you guys rock, you can listen on Twitter Tech
Stuff hs W. If it's a little longer, like it's
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(39:43):
is text up hs W and we will talk to
you again really soon for more on this and thousands
of other topics, because it has to have works. Dot
com chicks
Get in touch with technology with text stuff from how
stuff works dot Com say they're and welcome to text Stuff.
I'm Jonathan Strickland and I'm Lauren, And uh, this test,
we're not doing a listener request, although I would imagine
a lot of our listeners have heard about the subject
we're going to be talking about today. But before we
(00:25):
get into it, Lauren, what is your favorite implementation of
the concept of invisibility in FICTIONUS? Uh, probably the Ronnie
Lank cloaking device, Yeah, which the Klingon's managed to get
their hands on because I was to get the Bird
of Prey from uh well, they both had Bird of
(00:45):
Praise that could cloak, and the Star Trek University. Eventually
the Federation picked it up as well. We could really
really get into a full thing of us just talking
about Star Trek and cloaking devices as it turns out. Yeah, No,
that's a cool, cool implementation. Another one, of course, the
Predator being able to have that chameleon likability or I guess,
I guess the halo armor. Yeah, there's of course the
(01:08):
the Harry Potter invisibility. Yeah, the hay cloak with the
Marauders invisibility cloaks. So yeah, we've we've got all these
ideas about invisibility. It's of course been a popular concept
in fiction, whether it's fantasy or science fiction. In the
world of science fiction, of course, we have to try
and come up with a way of how would this work,
(01:29):
how would we manage to make something invisible? And well,
some people feel more obligated to do that than others. Well, yeah,
because some people would argue that if you don't do it,
you might as well call it science fantasy rather than
science fiction. But the the concept usually boils down to
the idea of somehow manipulating light so that bends around
an object and then continues on as if the object
(01:51):
were not there. So from an outsider's perspective, it's just
you know, emptiness or or whatever. It's whatever, see the
starf behind you or the wallopping willow or whatever. It excellent,
really well done. I was wondering where you're going to
go with the Harry Potter one exactly. So the interesting
thing is that there are people who are really working
(02:12):
on this technology. You guys out there have probably heard
about variations on real world cloaking devices, and you may wonder, well,
how is this even possibly attempted, and there are a
lot of different approaches, but one emerging field that we
wanted to talk about is meta materials. Right, because with
normal materials, perhaps obviously, normal materials do not bend light
(02:35):
around them so that you can see what's on the
other side when they're solid and opaque materials. Yeah, yeah, exactly,
Even a even a transparent window is reflecting some light
back to you. Right. The idea of a meta material,
at least in this particular implementation, because there's lots of
different potential ways to use meta materials, is to bend
(02:56):
electromagnetic radiation, in this case visible light around it so
that we wouldn't see it. Now, we're not there yet,
by the way, spoiler alert, Yes, um, we are working
slowly towards it. But let's put down a good solid
definition of meta materials to kind of start the conversation off. Okay, so,
first thing to keep in mind their artificial These are
(03:16):
these are materials that are man made, and they are
very different from natural materials because the properties that you
would find in any natural material are largely dependent upon
its chemical composition. So, for example, a bar of gold,
a bar of gold has the weight, the color, the density,
(03:37):
it has all of these things because of the nature
of the atoms of gold. Right. That's if it were
a different material, it would have very different properties, even
if you had it at the same physical dimensions, right
and so, And even though okay, a bar of gold
is also a man made object, you're rarely going to
pull a large chunk of gold like that right straight
(03:58):
out of the ground having minecraft or something without it
having some kind of impurities that you would have to
melt out or whatever it is that you do. But
basically it's all chemical exactly. Now, manty materials they get
their properties not just from the kind of atoms or
molecules that make up that mety material. In fact, the
chemical composition doesn't really ultimately matters they structure exactly. It's
(04:24):
it's how that material is physically constructed. And when we
say physical structure, we're not talking about something you can
see on the macro level. We're talking this is micro
to nano exactly, to the point where it's so small
that an optical microscope would not be able to show
you what that structure is. And a lot of this
was sort of theoretical. We'll talk about the history of
(04:46):
it until relatively recently, we've just now started to get
too sophisticated manufacturing processes that allow us to build these
super tiny structures that will affect uh well, that will
interact with electromagnetic radiation and interesting ways. Right. It's sort
of similar to the way that we've talked about nanostructures
(05:08):
having different effects on the world around them, then we
would normally be able to observe larger structures. Meta materials
are similar and a lot of them will interact specifically
with electromagnetic radiation in very interesting ways. So if you
look at electromagnetic radiation, if you were to to just
be able to stop the whole universe and just look
(05:31):
at a specific wave of electromagnetic radiation and be able
to break that apart, conceptually, you'd be able to see
that there are two major components of it, which are
electric fields and magnetic fields. Um, there's also the vector,
which is the wave's magnitude and direction. So all three
of these things together determine how they interact with any
(05:54):
given I reject exactly, and so conventional material usually only
in acts with the electric fields. Usually there are some
that interact with magnetic fields, but Generally speaking, the electric
fields are what are interacting with conventional material Many materials
can also interact with the magnetic fields, which increases the
number of ways it can interact with any given electromagnetic radiation.
(06:19):
Keep in mind, visible light is electromagnetic radiation. It's part
of that spectrum. It's a very narrow part of that spectrum,
which also includes things like ultraviolet light and infrared light,
but also microwaves and radio waves. Um. So this is
the stuff that would, at least in theory, if we
(06:39):
were able to build the right kinds of structures, allow
us to create an invisibility cloak for real zes or
at least some sort of of physical object that light
would bend around so you would not be able to
see it. And right now we only have invisibility cloaks
that bend microwaves around. The implementations tend to be very
(07:01):
specific to very narrow bands in that spectrum, right and
we'll talk about it. This has to do with the
specific micro and nanostructures of these objects, which we'll get
into in a moment um. But while we're talking about waves,
electromagnetic waves are not the only ones that hypothetically these
materials can interact with right, absolutely, anything that travels in
(07:23):
wave form can in theory be uh something that interacts
in a different way with a meta material. So seismic waves, earthquakes,
that those it travels in waves, just like you know,
it's hard for us to imagine in a way things
like electromagnetic radiation because we can't directly see those waves. Um,
(07:43):
we also can't well, I guess we can see earthquakes,
or we can see the effective earthquakes, right, we can
certainly feel them, certainly, So those those seismic waves that
travel through the ground, you could in theory create a
meta material that allows that stuff to just passed through
it as if it weren't it wasn't there, and then
imagine making a building out of that stuff. It wouldn't
(08:05):
even sway when the earthquake moves through. The earthquake would
just pass through it as if it weren't there. It
would just redirect. Yeah, it's the same thing with sound waves.
You could build I mean, I'm I'm picturing our sound
studio right now without all of this albeit lovely foam
that that Noll has put up on our walls. Instead
of that, the walls themselves could just be made of
(08:26):
a material that redirects the sound waves. They could either
absorb it or because again it all depends upon the
physical structure of the material itself. If you were able
to do that, you could have a perfectly soundproofed room,
so you would never have to worry about any sort
of bleed out either going out of the room or
coming into the room. And we would really like that
(08:46):
because often we have to stop when there's a siren
or a drag race or something going on outside, so
that you guys, I mean, I'm sure a couple of
them have snuck through anyway, but we try to limit
them also at will. Waves like ocean waves, those are
another form that I've seen. I've seen the Navy looking
(09:07):
into a strategy where they would have a special meta
material on the outside of the whole of ships to
make them more efficient in moving through the water, exactly
releasing all that drags so that you don't have to
worry about that. It doesn't have to do as much
work to move a huge vessel through the water because
you have redirected the waves as if you're not there. Also,
(09:29):
you could in theory, reduce the wake of a vehicle
moving through the water, so that the ocean itself does
not reveal the fact that an enormous like aircraft carrier
just bustled through. You wouldn't have a wake, it would
This to me is hard to imagine. It's hard for
me to imagine. Yeah, going all, you know, Scutty said
(09:54):
you cannot break the laws of physics, and I think
I think it was a little shortsighted. Actually, I think
mento materials kind of prove them wrong. But I mean,
clearly we're still working within the laws of physics. It's
just we're expanding our our knowledge of how they how
they work. We're just tweaking them a little bit, you know,
kind of you know, just a little thumb of the
nose at the laws of physics. So, alright, what is
(10:17):
actually going on here? How you know, we've talked about
what they are and what they do in general, and
we've talked about this structure issue. But let's let's get
down into it. Yeah, So, if you were able to
shrink down to a teeny tiny size and observe this
material on the nano scale, what you would notice is
that the actual physical structure of that material would be
(10:39):
made up of repeated patterns. They would be kind of
like a repeated scaffolding in a way. And think, again,
this is on the nano scale. You to to us
on the macro scale, it would just look like stuff.
Whatever it happened to be made out of. We went
notice that structure because it's far too too tiny for
us to see. But you would see these repeated patterns,
(11:00):
and those repeated patterns would be specific to whatever wave
it was supposed to interact with. Because here's the thing.
For meta materials to be effective, generally speaking, those structures
need to be smaller than whatever the wavelength is of
the whatever it's going to interact with. Right. This is
why we've had better success with microwaves than anything else,
(11:23):
because microwaves are very long wavelength as well, I mean
compared to light. Absolutely. If for red's the same way
and for red is a longer wavelength and say red, Yeah,
so you run into a building problem, just just a
structural issue here. Exactly how do you build something tiny
enough to interact with these very tiny wavelengths? Yeah, so
(11:45):
in order for you to have something that would be
able to shield an object from visible light, you would
have to make uh structures with such precision that those
repeating patterns would be just teeny teeny tiny, like yeah,
as building blocks would have to be like no bigger
than ten to twenty nanometers. Yeah, that's really super small.
(12:05):
And we've managed to do that kind of thing with microprocessors,
but we're talking about expanding that out potentially to a
three dimensional object. Ultimately, when you're looking at microprocessors, you're
really talking about two dimensions. You're talking about the height
and the width. There's no real Yeah, it's to the
point where you might as well say it's two dimensional.
So when you're talking about three dimensional object and building
(12:28):
that outward volumetrically, especially to cover say a car or yeah,
oh yeah, or an aircraft carrier or whatever. Obviously the
military carrier whatever, the military applications for this are obvious, right,
I mean any kind of cloaking device. So yeah, being
able to manufacture that out in a way that it
(12:49):
has a practical effect is an enormous undertaking. It's something
that is, uh, we're years beyond that, like or no,
that's years beyond us, I should say we we and
it not close together. As my point, we're kind of
shouting at each other exactly through the future exactly, so
(13:09):
although we can't see them because when they're in the
future in two they're invisible. But uh yeah, that's the
thing is that you have to have these super super small,
small small structures. And not only that, but visible light
takes up a spectrum. You know, we say the visible spectrum,
and you know the easy way of saying that as
the Roy G. Biv Right, You've got from red on
one end to violet on the other end, and that
(13:30):
and everything in between. And that's what makes a visible
light for us. Well, in order to be able to
shield something from visible light, you would have to somehow
engineer a meta material that would be effective for that
entire range of those wavelengths. That's really tricky. It's one
thing to design a meta material that works for a
(13:51):
narrow range of wavelengths. That is, it's I hesitate to
use the word easier. It's more realistic than effect creating
a material that would be effective across an entire spectrum
of wavelengths. So it may be that we never get
to a point where, using meta materials we create a
(14:12):
cloaking device that's effective for visible light. That doesn't mean
we won't create cloaking devices. We may do it through
a totally different technology, or we may have cloaking devices
that are cloaking devices for specific wavelengths like microwaves, because
radar uses microwaves. Right, So, a stealth bomber that has
meta material surfaces which means that the radar waves will
(14:36):
go straight through it and not bounce back, you wouldn't
have to have those super funky uh the panels that
are all at weird angles. Yeah, that whole episode right right.
The surface of stealth bombers right now operate by redirecting
those waves exactly. It's kind of like the idea of
just uh, deflecting the wave to some other direction ap
(15:00):
from the receiving station. Right. So, as long as the
receiving station never gets the waves back, it doesn't know
that there's an object. So you can you could go
on and make those things more aerodynamic at that point, yeah,
you could. You could completely redesign the self the weird
bulky looking thing. Yeah, I mean sure they were ridiculously
expensive and inefficient ultimately, but hey, they look cool. I
(15:24):
also like the Deloreans, so same. I mean, Deloreans show
up on radar like crazy, but that's that's that's another episode. Now,
there are different types of meta materials. There's there are
different ways of building meta materials to interact with various
types of wave links. So I'm going to go ahead
(15:45):
and preface this part of the podcast by saying, neither
of us are physicists, and electromagnetic radiation is a difficult
topic to wrap your head around when you haven't had
that as as your continual background for say thirty years. Yeah.
So if there are any physicists out there who cringe
(16:06):
as we start to oversimplify what's happening, I apologize to you. Now.
I am doing the best of my ability to explain
what's going on. Yes, and if we get anything wrong,
please do be gentle with us, but let us know, Yes,
please do, because then we can always do a follow
up and say, you know what, we were doing this
based on our understanding, and as it turns out, our
(16:26):
understanding was flawed, and here's how it really works. We
appreciate that. Yes, please be gentle. Alright, So starting off,
we have the electro magnetic band gap meta materials or
also known as e b M meta materials or just
a b M, because that's what the m stands for
So these manipulate light propagation, and they are either made
(16:47):
from left handed materials or photonic crystals left handed materials.
That means they're more creative, it means they're sinister. So
when you go to the old French being a left hander,
I consider myself sinister. Now, left handedness and electromagnetic radiation
is um a very particular thing and you've got to
(17:07):
be careful on how you define it. So with electromagnetic radiation,
like we said earlier, you've got the electric field, the
magnetic field, and the wave vector, which is that magnitude
and direction combo. Right, So you also have physical material.
So any given physical material has a couple of different features,
one called permitivity and one called permeability, and those are
(17:29):
the ways in which it's going to interact with any
given wavelength of electromagnetic radiation. Right, Yeah, Because your permitivity
is how it interacts with electric fields. Your permeability is
how it interacts with magnetic fields. And a positive number
essentially says that it has this kind of interaction. But
here's the thing you can actually have. You can create
(17:51):
a material that has negative permitivity and negative permeability. You
won't find it in the nature, or at least we
haven't found anything in nature so far that has both
negative permeability and permitivity simultaneously. We have made stuff that does,
and that stuff is called left handed yes and h.
(18:11):
So it's really interesting concept that you are able to
create something that has this negative permitivity and permeability. What
it ultimately means is that you could create a material
that resists waves as they impact that material. So imagine
creating a military vehicle out of this stuff and there's
(18:34):
an electromagnetic burst. This thing would actually effectively the material
itself would push back against that oncoming electromagnetic wave, leaving
the vehicle fine. So you could imagine that being really
effective for something like an electromagnetic pulse weapon that wipes
out electronics. Otherwise, if you're if you have it shielded
(18:56):
with this stuff, it's like the ultimate Faraday cage. Yeah,
it's like a field almost, but it's because of again
the physical structure of the structure of the material. Yeah,
there's there's no energy thing going on here. It has
nothing to do like you don't have to turn off,
switch off exactly. It's just the way the stuff is
(19:17):
physically built. It's it's unbelievable to me. It's amazing to
me that just by uh, specifically designing the structure, you
can dictate how electromagnetic radiation is going to interact with something.
And now there's also single negative meta materials, which would
have one of those two things, primitivity or permeability, be negative,
(19:41):
but the other one would be positive. Then you have
natural materials that have like the double positive, which means
the permitivity and permit permeability are both positive. You can
make meta materials that have that same stuff. Uh, I mean,
it all depends on what you want the meta material
to do obviously. Uh. Then there are others that get
restively more difficult for me to describe. So I'm not
(20:03):
gonna try because I know at that point I would
just be giving misinformation. But uh, that's the basic ideas,
the the idea of interacting with either the electric field
or the magnetic field or both in a way that's
different from your general natural materials out there. So this
all sounds like incredible science fiction technology to me. This
(20:26):
is all probably really recent research, right, Well, how about
late nineteenth century is that still recent? I mean, overall
from a geological time scale, it's like no time at
all has passed, but for for humans. Yeah, this this
is actually the whole concept is built upon observations that
(20:47):
were starting to come out of the scientific world in
the late nineteenth century. Back in a scientist named Jagaudie
chunder Bows experimented with microwaves and twisted structures that today
we would call artificial chirals. Chiral, by the way, is
essentially an asymmetric shape. It's one that if you were
(21:08):
to superimpose a reverse of its image, it would not
fit onto itself. Um. He found that by introducing randomly
oriented wire helisses as in the plural of helix uh
in a host medium, he could create a microwave lens. Essentially,
he was bombarding stuff with microwaves and he had these
(21:28):
little wire helix structures embedded into that material, and then
he would move the little helix helis sees around, changing
their orientation, changing their their layout, and he discovered that
that was changing the the effect of those microwaves. He
could focus it exactly, so he's like, huh, something to
(21:50):
do with the physical structure is affecting the way the
microwaves are behaving with this material, and that was the
very beginning. Some say, because there are people who argue
about whether or not this is in fact the origin.
But by the nineteen sixties you had scientists hypothesizing that
if we were in fact able to build stuff with
(22:12):
incredible nano precision, we could do so and make it
so that it behaves in a specific way when introduced
to electromagnetic radiation. There wasn't any way we could actually
do it at that time. Yeah, we wouldn't actually get
into that kind of production technology until the nineteen nineties. Yeah,
And in fact, really it wasn't until the two thousands
(22:33):
that you started seeing the first real forays into the
microwave world, where we were trying to uh specifically create
a meta material that would allow microwaves to pass straight
through it as if nothing were there at all, and
kind of around it. But yeah, kind of around it. Yeah.
When I say through it, over it, I guess technically, yeah,
(22:54):
imagine that the light like think of it almost like water,
you know how water. If you put a stone in
an in flowing water, the water will just flow around
the stone and then continue on as if nothing were there.
It's the same sort of things. In this case, we're
talking about light. It actually bends around the object and
then continues on not to us, it's as if light
is just passing straight through it, right, That's that's an
(23:16):
optical illusion. So if we were able to see in microwaves,
we would not see that object. It would just be
as if there was nothing there at all. So that was,
you know, kind of the beginning of it. But as
far as where we are now, we're really seeing lots
of effort going into making this technology more sophisticated. Uh,
(23:37):
And we're able to create much more precise meta materials
than we ever have been before. Oh yeah, A lot
of that has to do with three D printing. Talk
about that a lot on this show. We do. Uh.
For example, that microwave invisibility click that we were that
we've been talking about involved printing wires and patterns on
too circuit boards in order to create this this shield. Yeah, yeah,
(23:59):
that's pretty cool. So this whole microwave shield thing, it's
obviously the best example because those are the ones that
have had the most experimentation, the than the greatest success
rate so far. Again, it tends to be narrow bands
of the spectrum. It's not like it will affect every
wave length, but it has shown that this could be
(24:22):
possibly used for stealth technology, like or if you want
to turn it on its head, you could actually make
more effective antennas using meta materials. Right, instead of it
being something that that the waves passed through, it could
be something that is channeling those waves more effectively, either
to transmit or to receive, whether it's microwaves or whatever.
(24:45):
In fact, I've even seen talk about optical antenna's, So
it would be something in the light range, not necessarily
visible light, but in the light range that would be
really effective at transmitting and receiving because the meta materials
themselves were channel ling that radiation in a more effective
manner um. Again, we're getting to a point now where
(25:06):
I'm like, I understand the application, Understanding the mechanism is
getting more and more complex. And then there's the idea
of creating like an amazing microscope or telescope using meta
materials to create super lenses. So here's here's the thing.
When we talk about the nanoscale, and we talked about
(25:28):
not being able to see something with an optical microscope,
the main reason we talk about that is that you're
talking about trying to look at things that are on
a scale that's smaller than a light wavelength. So here's
the weird part in theory. You could use meta materials
that have a negative refraction index refraction. When when you're
(25:52):
talking about lenses, there's a thing called the diffraction limit,
and it's one of those things that like, the better
or lenses, the less problem you have with diffraction, but
ultimately you're going to run into it at some point
or another. The menty materials can start to make that
less and less of a factor. So as you have
this negative refraction index, which would allow you to look
(26:15):
at stuff that normally would be too small for you
to see whether that is a distant star. So you're
talking about a telescope in that case, or something on
the nanoscale, so you're talking about a microscope on that case.
And the the idea here is that, Okay, lenses focus
light by bending it right, UM, and the refraction index
measures how much a given material will bend the light
(26:38):
passing through it. Uh, you know, the way that an
object will look different when you view it through water
or through a wine glass or something like that. UM
and a negative refractive index means that the material is
bending light the wrong way, which could allow for this
very precise fine focus. Um, but it kind of goes
(27:00):
against just again your common sense of how things work, right,
because you're saying, oh, well, this just does it the
opposite way. But but that's that's the thing at all.
That's like saying if I jumped into water, I would
get more dry. Like it's something that goes so against
what are common experiences. It's hard, at least for me
(27:21):
to imagine it. It's difficult for me to have a
concept of how that works. But it does. But it does,
and it could be useful for a number of technologies
because a number of technologies in fact, to use optics,
how about fiber optic cables or optical discs like DVDs.
H that this kind of research could lead to huge
(27:42):
improvements in a DVD's data capacity or in fiber optic
cable transmission speed or power consumption. So one of the
things that I talked about on a forward Thinking episode
an upcoming forward thinking episode spoiler alert, folks, is the
whole field of photonics. The idea of creating electronic components
(28:03):
that are based on light rather than on electricity. So
the thing about photonics is that they tend that they're
incredibly fast, Like you can move a lot of data
at the speed of light. So when I say fast,
I'm not just talking about transmission speed, because really we're
talking at this point transmission speeds that are close to
the speed of light. I'm talking about how much information
(28:25):
you can move through that channel at once. So throughput
is probably a better word than speed. But the problem is,
especially when you get into things like quantum computers, you're
limited by how far you can you can extend these systems.
You would not be able to create at this moment
with our technology right now, a an internet based on
(28:47):
quantum computers. It wouldn't reach far enough for you to
be able to do that. I think thirty kilometers is
about the limit that you can get. And while we
could in theory build out a network that has a
density for that, when you're getting to places that are
you know, further out, Yeah, it's make working from Antarctica
(29:08):
really difficult, right but by using meta materials and improving
fiber optic technology, we might be able to address some
of those issues and be able to extend that kind
of of utility. Further, so then we are able to
have these massive nate you know, networks of fiber optics
that don't have any data loss issues or at least
(29:30):
fewer data loss issues, and be able to put everyone
on this incredible speed, and then we don't have to
worry about the whole net neutrality thing anymore. I'm dreaming,
I know, but still it's pretty cool. It's a beautiful dream.
And besides fiber optics and DVDs, we could also see
this helping improve technologies like ultrasonic technologies, anything that again
(29:54):
involves waves, so sound ultrasonic obviously the whole sound profing idea,
who stick shielding that kind of thing. Also, uh, you
know solar panels again you want to redirect that light.
So these are really cool potential applications of meta materials,
assuming that we get to a point where we can
(30:14):
produce them. Yeah, right, um, they could be the next
evolution of ultra light objects. We were just talking about
that in our camping episode. I mean, although this would
probably be a little bit of the price point of
many people are looking for hobbyist camping for a mere
three million dollars. Uh m, I t and the Lawrence
(30:34):
Livermore National Laboratory are working on three D printing stuff
that has super low density and super high stiffness and strength. Um.
For example, they can print these tiny lattices of polymers
and then coat those lattices with thin films of metal materials,
metal or ceramics or something like that, and then melt
out the original polymer, leaving these little, tiny, bitty hollow
(30:58):
tubes with walls you know, only like fifty to animeters thick,
that are incredibly strong, like able to bear loads that
are at least a hundred and sixty thousand times their
own weight. Again, hard to conceive, It's hard for me
to imagine. Meanwhile, scientists at the University of Southampton have
been working with materials that will adhere to a surface
(31:22):
when that material is exposed to light. What. Yeah, So
imagine that you've got a wall, maybe it's made out
usually you're talking about a dielectric wall, so something that
can conduct electricity. So like, let's say that it's a
stainless steel wall or some sort um, and you put
this thing whatever it happens to be against that wall,
and as long as it is being stimulated by light,
(31:44):
it sticks there, and if you were to take away
the light source, it would no longer stick there. And
it's because it's a meta material that has these little
vibrating electrons sites that would interact with electrons that are
on the surface of the wall. It's health so it's
an electron electron interaction that doesn't involve repulsion. And that's
(32:05):
as much as I can tell you, folks, because I mean,
once I started looking into it more, I was like, Okay,
I'm gonna have to take a full course in physics
for me to really understand what's going on on a
physical level. But the cool part is that this could
potentially become a new way of developing brand new technologies
that we can't even really conceive right now. Yeah, that's
(32:27):
kind of a new fundamental force. Yeah, it's essentially the
discovering that wait a minute, there's something else that that
can happen with under these specific circumstances that we didn't
know about, and it is a fundamental force, which is incredible.
I mean it, this is an amazing scientific discovery. So
even if there's never like a practical application, just knowing
(32:47):
that this is another way that our universe works is
a valuable lesson. Oh of course. Um. Meanwhile, over at
the University of Texas at Austin, they've been working on
creating these meta material mirrors that are only foim, they're
thick that can double the frequency of infrared radiation that
hits it. Okay, So if the incoming radiation has just,
for example, a wavelength of eight micrometers um, the outgoing
(33:11):
reflection will have a wavelength of for micrometers um, which
is a pretty awesome feature. But the researchers are also
saying that they can possibly fine tune the structure to
adjust the reflection to other desired wavelengths um. The mirror
is made of a bunch of wacky stuff, including indium, gallium, arsenic, aluminum,
(33:33):
and gold. But that's a little bit beside the point
I just found. I was like, arsenic is in there.
That's cool, and how I deal with That's what? That all? Right? Um?
But but so you know, being able to convert the
frequency of wavelengths at will would be incredibly awesome for
a bunch of different optical purposes, like miniaturizing laser systems
or improving optic space sensory tech. Yeah. Yeah, In fact,
(33:57):
I've I've seen a lot about meta materials used to
help create these manature laser systems, and you might think, well,
what's that good for. We'll go back to that photonics
discussion we had just a moment ago that would be necessary.
If you want to have a microchip that is working
under photonics and not just electricity, then you have to
have these lasers that generate the light and by manatorizing it,
(34:18):
that's what makes it possible. Otherwise, you know your components
are going to be larger, which means your devices have
to be larger in order to take advantage of that
photonics technology. So this is really promising. Then you have
this This was again one of those things where I
read it and I thought, what some folks at Northwestern University,
some scientists have been working on a material that would
(34:39):
act the opposite way you would expect it to based
upon our experience with the world around us. So imagine
you've got a cushion, and when you sit on that cushion,
instead of sinking down into the cushion as you would
with any normal cushion, the cushion pushes back against you
and actually rises up. Or imagine that you've got some
sort of silly putty. But instead of when you pull
(35:01):
on the silly putty and it stretches way out, it
starts to compress as you pull on it. In other words,
it sounds like we're talking about Harry Potter again. It
is physically behaving the opposite of what it should if
it were just a decent, law abiding material. And here's
the crazy thing is that they're scientists who are working
on creating material that does this stuff. Essentially, when you
(35:24):
when you pull it, it compresses and when you compress
it it expands. And they said that the way they
did it because normally, if you made a material like
this that could do this, it would be very unstable
and it would collapse in on a more stable, uh structure.
That what they did was they started by creating a
stable structure that already did this, so when it collapses,
(35:47):
it's collapsing into the the base form of this so
that when you pull on it, it compresses. And uh.
They explained the concept because again they're they're working on this.
It's not like they have big old piles of this
flubber like stuff out there. They're working on it, and
it's very much in the hypothetical phase. They described it
(36:07):
by by describing, uh, four atoms that are in a
horizontal line and uh, and trying to pull those atoms
apart would would cause them to compress closer together. That
illustration didn't help me at all. But that's not due
to them. That's because I'm dense. So I'm not blaming
(36:28):
it on you, Northwestern University. I'm blaming it upon my
own limitations. But I think, what again, just by making
this material a specific structure, it has these very different properties. Yeah,
I think that part of this is so hard to
wrap our minds around because it's i mean, not only
is it breaking the laws of physics kind of sort
(36:49):
of um, but also because it's also new. Um that
there was a market research company called BCC Research that
just this year estimated that the global market for mety
materials is going to expand from like two eighty nine
million dollars in to some one point two billion by nineteen.
(37:10):
So because the future is bright, it's hypothetically picking up
and it's it's the future is not just bright, it's invisible.
But but to be to be fair, to be fair,
this this proves, like you say, two million dollars, which,
don't get us wrong, that's a lot of money. We're
not saying it's a little money. If you think it's
a little money, give us two million dollars. But it's
(37:33):
a drop in the bucket compared to other industries. It's
really proving that mety materials are in their infancy. So yeah,
well it's it's incredible to think of the sort of
applications that could potentially come out of this. I mean,
imagine a city that's earthquake proof. That or a bridge
that really is earthquake proof that the earth is shaking
(37:55):
around it and the bridge is just fine. That's it's
it's it blows my mind. It's incredible. I would like
that future. It would be an awesome future, be fantastic.
So we're really excited to see where meta materials go.
We're really excited that again, this is properties that are
just based upon the physical structure of that material, has
(38:16):
nothing to do with like, hey, we we managed to
make this new you know, stuff that is really unstable
and decays almost immediately. So that's unfortunate, but look at
the cool thing it does for the split second it exists.
That's not what we're talking about. This is stuff that
has permanency because again it's just the physical structure at
that nano level that gives it that ability. Wow. All right, Well,
(38:40):
now that we have melted our brains and hopefully stimulated
your brains, I would like to invite all of you
guys to suggest any topics you might want to hear
about in the future. Maybe you said that was really interesting,
Can we talk about something like really simple? Now? Maybe
maybe the technology often Kitten's kitten technology. Obviously that would
(39:01):
involve a deep discussion about YouTube. Just let us know
if you have any suggestions, or you have questions, or again,
maybe we have covered something but perhaps are limited explanations.
You feel we're we're not rich enough, and you have
a way of putting it into words that we need
to share with our listeners. Let us know. Sleace us
(39:21):
an email. Our address is tex Stuff at how stuff
works dot com. Or if the message is really short,
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Stuff hs W. If it's a little longer, like it's
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(39:43):
is text up hs W and we will talk to
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