So let’s say you’re the groundskeeper at a
magic-based boarding school and you’re
trying to smuggle a dragon out of a castle.
Too out there?
Ok, you’re the captain of a Klingon vessel and
you need to travel through a sector undetected.
How would you do it?
If you said some kind of invisibility
cloak, that would probably work.
Unfortunately, there’s no such thing
outside of Harry Potter and Star Trek.
At least, not yet. It’s true we can’t hide people,
dragons or space ships from sight.
But in the last decade scientists have come up
with amazing new materials -- and clever uses of
existing ones -- that could one day let objects
or even people hide in plain sight.
[REACTIONS INTRO]
When people talk about an invisibility cloak or
a cloaking device, they’re actually talking about
a range of ways to achieve the same goal.
That goal is making it hard or impossible to see an object.
Seeing something requires light -- and 2015
just happens to be the International Year of Light.
When light bounces off an object and
Hit your eyeball, your brain interprets color,
brightness and other variables to represent what we think of as sight.
The easiest way to make something invisible
is to disrupt that sequence of events.
Stealth technology used on planes and ships does
something similar by absorbing the energy from RADAR.
like visible light, RADAR bounces
energy off an object to “see” it.
If no light comes back, the object doesn’t show up on RADAR.
You can kind of do that with visible light, too.
Black objects reflect very little light.
Unfortunately, our brains have already figured
that trick out, so you can’t just put whatever
you’re trying to hide behind something black.
Instead, some of the most promising invisibility
research helps light avoid an object all together.
In 2006, researchers at Duke University first
described something called a metamaterial
that could bend light around an object.
In theory, if you looked at the spot where the object
was, all you would see is the background behind it.
How does that work?
Metamaterials direct light around an object.
The material could capture light coming in from
one direction, channel it around the object and
spit it out 180 degrees from the direction it came in. The object
in the middle would disappear to the observer.
They’re called metamaterials because their man-made
structures let them affect light in ways normal
materials can’t. Some are made with superthin wires of silver and silica.
Other invisibility devices are made with carbon fibers
or even silk -- but before you get too excited: yes,
I can still see you when you’re wearing that kimono.
Researchers have figured out how to disguise larger
objects and they say they’re getting closer to
making cloaks that would work with visible light.
But metamaterials aren’t the only way to make something invisible.
Scientists at the University of Rochester
arranged four standard glass lenses so they created a region of invisibility too.
It doesn’t have quite the same potential as
metamaterials, but the researchers behind the
technology say it could help doctors see through
their fingers when they’re doing surgery, or
let drivers see what’s in their blindspots.
Maybe they could figure out a way
to make my selfie stick invisible, so
I don’t have to be seen with a selfie stick.
One more way to be invisible?
Instead of bending light around on object, just mimic it on the other side.
It’s the way some animals like cephalopods and
chameleons camouflage themselves, by changing
the color of their skin to match what’s around them.
Video cameras and screens can recreate this active camouflage technique,
which militaries are particularly interested in.
The British defense contractor BAE came up with
a system like that for tanks, and they say
it could be ready for use in just a few years.
Thanks to the ACS Photonics journal for making this video possible.
And thanks to you for watching.
You can check out other videos about light and learn
about how putting away your smartphone could
help you sleep better or how scientists see atoms.
Be sure to hit the subscribe button for more
deee-LIGHT-ful videos every week.
See what I did there?
The International Year of Light is a global
initiative to highlight the importance of light
and light-based technologies in people’s lives.
To learn more check out www.light2015.org
and thanks again for watching.