- Hey it's me Destin.
Welcome back to Smarter Every Day.
If you can't tell, I am on a kayak here.
And we have a lot of the kayak.
I guess it was a week ago I uploaded a video
to the second channel.
And we were trying to fish, right Trent?
- [Trent] Yeah.
- Oh you're over there.
- [Trent] I'm over here.
- So we were fishing because we've been working hard.
And we just wanted to relax.
The fish weren't biting.
We're out here on the kayaks and we decided to just
play with our headlamps in the water.
There's milfoil all in the water here.
And we discovered something really really fun
with our headlamps underwater here.
And I'll just let you watch a little bit of that video.
- [Destin] Okay, you ready to show them?
Get your flashlight, go to the other side.
So we figured this out.
Put your light in the water.
And you could see the beam right?
Now stick your arm further underwater.
And aim up and it bounces off the top of the water.
How cool is that?
Neat.
Okay now if you go too far, it'll break through.
That's cool, there's a thing called Snell's window.
You know about Snell's window?
- [Trent] Nah uh.
- If you're scuba diving for example,
and you're in the water, and you look up,
you could see the sun.
But you could see it from a certain angle.
So there's this window right above you.
Where you could see the light coming through it beyond that,
the light reflects out.
And so what Trent student over there has to do
with the index of refraction water.
Can I try it?
- [Trent] I'm moving with the-
Yeah.
- [Destin] Here trade the lights with me.
Here's the camera.
- [Trent] Oh dude that looks great from over here.
- [Dustin] Isn't that neat?
- And then it should just bust through.
Look at that.
You could see the beam goes through.
- [Trent] Dude it bends more with the-
- Did you see what happens though?
Like half the beam punches through the water.
Half the beam doesn't, watch.
So the beam in the water goes dark.
So coming up, up, up, then it starts to go dark.
And the whole thing punches through.
- [Trent] Whoa.
- Okay fast forward to now.
We've got lasers now because-
some people said in the comments that it would
be really cool if we did this with lasers.
Do you have those laser goggles?
I gotta say this is the only time I've ever wore lasers.
HaHa Laser goggles..
We look like goobers man.
Alright so here we go.
We got a green laser.
It's not waterproof so I have it in a bag.
For 532 nanometer laser.
And I'm wearing 532 nanometer goggles.
Which means I can't see this.
I have no idea what's going on.
But if I this, okay I can see that that's green.
So what we're going to do is we're going to continue
to play with words I could not pull from my brain
in the last episode, which was:
Total Internal Reflection.
That's what's going on here.
So we're going to play with Total Internal Reflection.
I have a bunch of goodies in my kayak.
Okay you ready?
- [Trent] You have no idea how goofy you look.
- This makes so much-
I love it so much!
Alright, so first up.
Oh that's heavy, it's making my kayak move.
Okay I have sheet of acrylic.
It's moving my kayak cause it's so big.
I'm cutting the light off.
Gah-lee my nasty mustache.
So if we shine this laser into-
Oh that looks red.
I could see in the the viewfinder.
If I shine this laser into the side of this
square acrylic block, you can see If I'm at a 90-degree
angle to the block, the laser just goes straight through
and bounces off the other side
and diffuses a little bit, right?
But what happens if I angle this laser and I bounce it.
Look at that, the whole block lights up.
And reason it lights up, is because that angle up top
is an acute angle and all that light bounces around
on the inside.
Dude this works so much better than I thought it would.
Alright so isn't that neat?
Okay so if we go down-
Let's go down and see if we can light this block up.
Let's do it, boom we hit the corner.
Look at that stuff starts bouncing around.
So this Total Internal Reflection is a thing.
So if we just go straight across, you know.
Some stays in some stays out but-
Oh look at that what just happened?
Oh my gosh I'm bouncing it back and forth.
Did you see that?
You can't see that can you?
Do you see that?
What's happening?
It's bouncing back and forth on the inside.
- [Trent] I can see it with my goggles over here.
- You could see it with your goggles?
Okay here we're going to do it this way.
Boom, right there.
You see it bouncing back and forth?
Can you see it?
Can you zoom in?
- [Trent] It's really hard to see it on camera.
- Is it really?
How do you know?
You got laser goggles on dude.
- [Trent] I can see through the viewfinder.
- So long story short if you could bounce a laser underneath
the angle of incidence,
then you can get what's called Total Internal Reflection.
And this happens when you have two transparent materials.
Two transparent materials like air and water or acrylic
and air or acrylic and water.
Okay so that's acrylic.
Let's move on to the next thing.
Do we have the fiber optics?
- [Trent] Yes we do.
- Let's get the fiber optics on the kayak.
Okay Total Internal Reflection, you totally-
Oh I don't need these.
You totally know what's up with that.
So we get a flashlight, we got fiber optics.
I can't believe we got all this stuff on the kayaks.
So you know that that's how that works right?
So you got the light that's going into the fibers
and it's bouncing around on the inside of the fiber
and it's going all the way through.
You know what's about to happen.
Where's my laser?
(laughs)
Oh shoot!
Alright here we go.
Laser, look at that.
Same thing, except I can't see it because
I have laser goggles on.
But as I move around, I'm assuming that it's going through
the fibers all the way to the end.
And the reason it's able to do that is it's bouncing
all the way down the fibers like a pipe.
Total Internal Reflection.
This is all stuff you know.
This isn't new stuff.
So we're just demonstrating that because it's awesome.
What happens if I shine these fiber-optic lasers
into the water?
Oh it kind of looks like a laser flashlight inside that.
Okay, okay alright so now the way that fiber-optic works,
is really interesting.
I happen to bring a bigger version
of this fiber-optic with me.
This is a large dowel of acrylic because obviously this is
what you take on a kayak.
So the way this works-
I'm going to cut this off.
This is so going to look like a lightsaber dude.
Oh golly.
Are you ready for this?
Ready, one, two.
Whoa.
- [Trent] Put your goggles on.
- Oh yeah my goggles I'm sorry dude.
Thank you.
Oh man.
Does it look awesome?
- [Trent] It does look amazing.
- Okay can you see through?
- [Trent] I could only see it through the camera.
- Yeah because we're being safe.
- [Trent] It looks incredible.
Okay so the reason this looks like a gigantic fiber-optic
is because it is.
You could tell that it's an optic cause of the way it is.
Alright so you've got this low angle of incidence here,
it's amazing.
- [Trent] Put it in the water.
- Can I light up the whole water?
I can't see that.
Is it lighting up the water?
- [Trent] We're about to look.
Oh my god.
- Is it lighting up the water?
I've taken up-
It's like a big flashlight at the end.
I don't care, I'm going to quit talking and just do stuff.
You could make a camera that would see all the way
to the bottom, couldn't you?
It's a light pipe.
- [Trent] A light pipe.
- You could totally see if it was polished on both ends,
you could make a camera that could would go
all the way to the bottom.
Alright we brought a gigantic piece of acrylic on a kayak.
So we've done the square acrylic.
We've done the fiber-optic, both small and large.
It's time for the Christmas ornament.
Okay, we have a Christmas ornament
and we've got murky water below.
We're going to need goggles for this one.
Oh that's acoustically pleasing.
You want to hear that.
(bubbling)
That was really nice so-
Oh we got some milfoil in there.
Oh it's that's gonna-
That's gonna make it more interesting.
Just dudes on boats with lasers, that's all this is.
Freakin' lasers on kayaks that's all this video is.
Alright so here we go.
We should be able to see the light go straight through.
And I have no idea what's-
I can barely see it.
You could barely see it.
But what should happen-
I'm going to turn this off here.
But what should happen, is if I change the angle inside
we should get some weird bouncing that's going on, right?
Yeah we do, let's get up here close.
So we're straight here.
So we're firing straight inside right there
and if I start to bounce things off the inside by shooting
it like across the cord instead of the diameter,
we get all kinds of weirdness.
What would be really cool is if we could take a shadow
graph of this, if we could like blast this onto a large wall
we would see all the microbes and
little things living inside there.
Internal Reflection does not have to be total.
So if you meet this interface between the glass and the air
for example, some of the light goes out
some of the light stays in and so that's why
Total Internal Reflection is so cool.
Oh look at that, when I hit that seam-
You see that?
When I hit the meniscus or whatever that's called
at the top where it curves,
it just totally blasts the whole bulb.
You see what I'm saying?
It makes a huge globe so boom.
I hit the curve, lights up straight across doesn't light up.
That's fun, we're having fun.
We're learning things.
We're learning things on kayaks with lasers.
Okay so now it's time for more good sounds, here we go.
I think it's time.
You think it's time?
- [Trent] It's time.
- Laser under water.
We're going to see if we can bounce the laser up
off the bottom of the water.
Here's the Christmas ornament.
Everybody knows what's going to happen.
If the angle that hits the top of the water from underwater
is less than 50 degrees,
then it'll bounce back into the water.
But if it's above that, it'll punch out.
I just want to see it from underwater.
Okay here we go.
Tilt it back down at some point,
all of the light should bounce underwater.
You should see the beam get lighter and lighter
as I pointed up more that reflected beam.
So as it's laying down, you should see full
laser beam in the water.
As I tilt it up and it bounces off the top,
that reflected beam should get lighter and lighter
as I go up and then at the maximum angle once it hits
the critical angle, the one inside should go dark
and all the light should come straight out.
Which is completely rad.
Alright so in this video we talked about the ability of
light to bounce on the inside of an object in a certain way
called Total Internal Reflection.
I would like to tell you about a book that made me
internally reflect as well it's called Just Mercy
by Bryan Stevenson.
This episode of Smarter Every Day is sponsored by Audible.
And I just really want you to read this book.
Bryan Stevenson is the guy that decided to be the lawyer for
Anthony Ray Hinton who was wrongly convicted of murder
in Alabama, sentenced to death row.
Bryan Stevenson came to his aid and helped
Anthony Ray Hinton get out of death row.
It's an amazing book.
I loved it.
I made me reflect internally about my role in society
and how I could help those without a voice.
So please go check this out by going to Audible.com/Smarter
or texting the word smarter to 500-500
The first books free.
You can get two free audible originals.
This is a big book for me.
I mean in terms of making me think about my place
in the world and what kinds of things
I could do to help others.
So again you could get a free book or a free 30-day trial in
Audible by going to Audible.com/Smarter or texting the word
Smarter to 500-500 I highly recommend this book.
You will totally dig it.
So anyway, thank you for enjoying Total Internal Reflection
time with me here on the river.
Yeah, that's amazing.
That's really cool stuff, so I hope you enjoyed that.
Last thing, feel free to unsubscribe to Smarter Every Day.
If you feel like this video earned it.
By unsubscribe I mean you could unsubscribe and then
resubscribe maybe, if it earned it.
And then click the bell to turn notifications on.
If not, that's no big deal but I hope you enjoyed this.
I mean like playing with Total Internal Reflections
on a kayak, it's just absolutely awesome so I hope you
enjoyed this half as much as I do.
I'm Destin, again feel free to subscribe.
Getting smarter every day.
Have a good one, bye.