This Invisible Light Shows Us What Our Eyes Can’t See


TRACE DOMINQUEZ: Hey
guys, Trace here. And today we’re going
to be doing something a little bit different. Some of you may
recognize this set up. We used to do a show
called DNews Plus, and it was a show
where essentially we’d come across topics and we
didn’t have enough time to talk about them in our
regular Seeker videos. Or maybe I just got
really excited about it, and wanted to talk about
it for a long time. So that was what
DNews Plus was for. But a while ago we put
DNews Plus on hiatus, and since then
we’ve become Seeker. So welcome to Seeker Plus. We’re going to spend a little
while talking about something that we discovered that we
just couldn’t wait to tell you a whole bunch of stuff about. There’s no B-roll. There’s no music. It’s just you and me and
my notes and some science. So let’s kick into it. Today we’re going to
talk infrared light. Because you know, there’s talk
lately about infrared light replacing Wi-Fi. Infrared light replacing
Wi-Fi, can you believe that? I know, it’s shocking. So that got us thinking,
how would that work? And then we you
started thinking, what is infrared light all about? You hear about it all the time. It’s used in a variety
of different applications across the things that you
do on a day to day basis, and you probably never
even think about it. Light is everywhere. You know this, I know this. The only reason you
can see me right now is because light is
coming out of your device, and there are
lights in this room, and the camera is
picking up light. Light is everywhere. It’s very important. Light is just electromagnetic
radiation, just little bits of energy that it can
be picked up by your eyeballs or by the camera and
are being emitted by all sorts of
different things. That energy travels
through space in waves, things like radio
waves and microwaves and x-rays and UV light and
visible light are all light. They’re all in the
electromagnetic or EM spectrum. And they’re all
based on wavelength. We divide them up
into different groups. Because that’s what
humans love doing, is dividing things
up into groups. But the EM spectrum
is just that, it’s a spectrum of different light. And we’ve just picked, these are
the ones that we like the best. Visible light isn’t
the best light, it’s just the light that our
eyeballs have chosen to see. “Chosen” to see. We interpret visible
light with color. The shortest of those
wavelengths of light are violet, and the
longest are red. So knowing this gets you to
how infrared was discovered. A German dude moved
to England in 1757. His name, Sir Frederick
William Herschel. He built telescopes
and eventually he discovered Uranus. In 1800, he directed
sunlight through a prism and it made a rainbow. Ah, pretty. You can do this at home if
you happen to have a prism. He measured the temperatures
of each of the colors. Probably wouldn’t have
thought to do that, but this guy thought of it. And he found that
the temperatures increased from violet to red. Violet was cooler,
red was warmer. That’s interesting, right. But then he saw that it
was even higher if he moved a little bit further past red. It was warmer. So there was something
there that he couldn’t see. There was no light
in that rainbow, but the thermometer was
still picking something up. Cool right? Infrared light is
what was there. He discovered this
thing called infrared. It’s on the other side of red. It’s the first time
someone had found light that we could not see. Now the European Space Agency
has named their infrared space observatory after Herschel. Pretty cool. Infrared light is
next to visible light on the electromagnetic scale. It’s on the reddish side. Infra meaning below red. Red of course,
meaning red, infrared. OK, you got it. So infrared light is
just wavelengths of light that are longer or
have a more distance between the peaks of
the waves and then one side of the visible light. Ultraviolet, UV light,
makes sense, right, on the other side of violet. Pretty cool. Everything gives off
infrared radiation. You are, I am, your kitty cat
is, everything is giving off infrared radiation. Unless your thing
is absolute zero. If your cat is
absolute zero though, that probably wouldn’t
be good for your cat. That’s where all the molecules
in the thing stop moving. It’s the coldest possible
temperature that we know of. It’s negative 273.15 Celsius,
negative about 460 degrees Fahrenheit. The hotter something is,
the more molecules and atoms are going to move
inside of that, right. Boiling water, those
water molecules are just zooming
around in there. Frozen water, they’re just kind
of vibrating, not really moving at all. So the more something
heats up, the more motion it has inside of it. And that produces
infrared radiation. But things that are cold,
even though they’re not moving as much, are still moving. So they’re giving off
infrared radiation. Ice cubes give off
infrared radiation. And if something
is not hot enough to give off any light at all,
it can still be giving off infrared radiation. And you can feel
that because you can feel infrared radiation in
the same way that Herschel did. It’s heat. One example we found on
a website that we liked was charcoal. It doesn’t have to be
glowing to be hot, right. If you put your hand near
charcoal you can feel its heat. That’s infrared radiation. This is something I
learned very early on. Some of you know this. I am a blacksmith. So I hit metal with a
hammer, and sometimes that metal is not glowing. It doesn’t start glowing until
like the 1,300 degree range. But if it’s 900 degrees or
1,000 degrees, it’s still hot, and you don’t want to touch it. But you can feel the
infrared radiation coming off of the steel. So infrared is everywhere. You can’t see it,
but you can feel it. And hot things emit a lot of it. But just knowing that
is kind of a fun fact that you can tell
people at a party. But Seeker Plus, that’s
not what we’re all about. We’re all about let’s
push it past that, right. How do we use this knowledge? What can we do with
infrared light? It gives off heat. So we can use infrared
to measure how much heat is being emitted by
something, as long as we build a camera
that can read it or we can feel it somehow. An obvious thing comes to
mind like thermographic images and night vision. That is using infrared heat. So you have this special
camera that picks up the infrared
wavelengths of light, and then it can
display them for you. And we’ve seen those images. They look super trippy. It picks up the
heat off of objects. So different parts of
a body, for example, are going to be
hotter or cooler. And the background is
blue and the hot things are white and red
and yellow, you know. It’s really, really cool. And even at night, people
are giving off warmth. So you can use
those to spot things like prey or other humans or
even something someone touched a while ago that hasn’t
cooled off yet enough. Very important. And there are also
electronics that can create images using infrared
light using special lenses and sensors to enhance
what you and I just can’t see with our sad
little evolved eyes here. Infrared light is also
used in astronomy, because it can
pick up things that are too cold to emit light. Because as things cool
off and that motion stops, sometimes they’re
not energized enough to release light
that we can see. So infrared is a way to
see those things still. Also, because those
wavelengths are so long, longer than even red light,
it can cut through things that regular light
would be blocked by. So let me give
you a quick aside. The reason the sky is blue is
because blue light scatters more easily than any other
type of light, right. So the light hits
the atmosphere, it scatters all over the place. But when the moon goes
low on the horizon and it turns orange,
that’s the red light not being scattered as much. Infrared would
mean that it would scatter even less than that. So that means that there’s
a nebula in between you and something, you might be able
to see parts of it in infrared if you know, it’s a
very small nebula. But really, if it’s just dust
and gas and things in the way. So there are
wavelengths that can cut through some of those
things that are blocking you from seeing them out in space. And astronomers
know this, so they can utilize these methods
to see those things. Infrared wavelengths
get absorbed, however, in the lower
atmosphere, which sucks. So you have to go above
it like into the mountains or into an airplane
or into space. And that way the
infrared light doesn’t get screwed up before it
can get to your telescope. You can also send up
infrared space telescopes like we did in 1983 with IRAS. It’s an Infrared
Astronomical Satellite, and it mapped the entire
sky in infrared wavelengths, which is pretty cool. They found six new comets,
the core of our own galaxy, and evidence that there
might be other planetary systems around stars. This was in 1983. Really awesome stuff. It’s also used to study
the earliest things that we know of in our universe. So galaxies that
are far, far away and that are moving away
from us that are pretty cool, have cooled off. We can still see those
with infrared light, right. But there’s this thing that
astronomers know about, and maybe you’ve heard about
as well, called red shifting. Which means things
that are far away and that are moving really fast
shift toward the red spectrum. Because the light that
they emit gets longer. It gets stretched out. Which means it’s shifting
toward red, red shifting. The best way to see
that, of course, also an infrared telescope. Basically, infrared astronomers
get to see what the rest of us can’t see with our eyes. It’s really, really cool. Speaking also of
satellites, weather images taken by satellites are
often measured in infrared, because you can get
pockets of heat. You don’t have to
look at clouds. You can see air movement and
measure the different amounts of heat coming out of that air. You can also take the
temperatures of clouds and get hot and cold
places within those clouds. You can also see if the
cloud is producing rain, because colder clouds
are raining harder, which is pretty interesting, right. The satellite just
has to say, oh, that one’s a little
colder than this one. Must be raining
harder over there. If there are no clouds at
all, the weather satellite isn’t useless, it
can take measurements of the surface temperatures. And in different
places it’s going to have different temperatures. This is how we know
that say trees maybe reflect less heat than
something like an urban area. And these are just a
couple of examples. Infrared is, speaking of trees,
used to detect forest fires. It’s used to heat saunas. It can penetrate
through paintings and reveal what
is underneath them so we can see if a painter
used the canvas more than once. Which a lot of
really old paintings, that’s what they did. It can be used by your
remote control device when you point it
at your television and tell it to
change the channel, it flashes an infrared
light across the room that your TV picks up. Really, really neat. They’re even using infrared
in the medical field to detect things
like breast cancer, or helping with skin disorders. And Google shows a lot
of light therapy results, although there’s not really
any credible sources on that. Some people sit
under infrared light because they say
it helps them feel better, which is interesting. Infrared radiation sounds scary. But it’s not radiation
like nuclear radiation, it’s light radiation, right. That said, infrared, even
though it’s just heat and you’re just giving
it off all the time. I mean, unless you’re sitting
in a 98.6 degree room, you’re giving off infrared
radiation into the room. It can still be dangerous,
because you can’t see it. If someone were to shine a
really bright infrared light, and I’m putting
“bright” in quotes here. So if you put bright infrared
light into your eyeball, normally bright
lights cause something called blink aversion. You blink to protect
the inside of your eye. Infrared light you can’t see it. So you can damage
your eye with that. So one, don’t do that. But two, really interesting
and also kind of strange. The thing about not being
able to see it though, is a little
disappointing, right. Because you know it’s there. Like I want to be
able to see it. I want to see infrared light. Wouldn’t that be cool? You could see all of these
little things flitting around. You could see temperatures, and
you could see pockets of air. That would be so cool. But even though we can’t see
it, which is disappointing, there was this one
specific science experiment which shows that we
might be able to detect, which is really cool. One experiment shot
infrared photons at an eye. And if two photons hit the same
receptor one after another, it created a photon
of visible light. But that light was
not red it was green. Which is weird. Science is cool. Anyway, we can’t
really see infrared, and neither can most animals. But snakes, they can
sense infrared waves with pits in their mouth. Vampire bats and bedbugs,
they can sense infrared. And some animals can
see ultraviolet, again, the other side of the spectrum. But that’s kind of like a whole
other episode of Seeker Plus. So that’s infrared. We had so much fun
looking into this. It’s the heat that’s given off
by everything that we can’t see except one specific
incidence, in which case then it was kind of
green which is weird and a little mind blowing. But we use it to predict weather
and learn about the universe and turn on our TV and see if
Picasso screwed up his painting and started over,
which is great. Because sometimes
we all screw up. Thanks so much for watching
this Seeker Plus episode. Let us know down in the comments
if you like this format, because we’re trying
all sorts of cool things with this new
Seeker re-branding. And we really want to
know your thoughts. I’ve got all of your comments. I keep reading them
every single day. And thank you so much
for subscribing to us and sticking around and
watching this episode. So tell us, what did you think? And also tell us if we missed
anything about infrared that you think is really cool
that we should also think is really cool. Because maybe we’ll use that in
future episodes of Seeker Plus. Light is cool. It’s real– well, and
sometimes it’s hot. It’s complicated. Anyway, thanks for watching. Come find me on
Twitter @TraceDominquz. Come find us at Seeker. See you next time.

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