And I'm with Destin in Alabama. What he's about to do is capture on a Phantom

camera at a 1080 frames a second a hawk - that one - catching a target.

But today we're going to talk about sound. First things first.

The Raptor Center takes care of raptors that have been injured, or would otherwise not

be able to survive in the wild on their own. For instance, this bald eagle named Spirit,

who was hit by a car that damaged his beak.

Okay, so that is the bald eagle.

Very interesting sound that it makes. But what I'm interested in today is the recording

of sound. It hasn't really been that long in human's

history that we've able to record sounds. In fact, it wasn't until 1859 with the invention

of the phonautograph in Paris that we first recorded sound.

It really blows your mind to listen to this. What you're about to hear is the very first

recording ever of any kind of sound.

One thing I found fascinating was that these

large birds have such high metabolisms that in order to figure out if they're hungry or

not all you have to do is weigh them. And if a bird weighs too much it means it's

not hungry and so they won't bring it out to fly, 'cause it might not come back.

It's not hungry, it's not gonna obey commands to get little bits of food.

But let's now time travel to 1860 and listen to the very earliest recording of the human

voice. What you're about to hear is the voice of

the inventor of the phonautograph signing a French folk song.

Three years after that recording Abraham Lincoln delivered The Gettysburg Address and three

hours before he gave the speech this photo was taken.

The only known photo of Lincoln at the historic event.

It dedicated a cemetery in Pennsylvania to the Battle of Gettysburg, the deadliest battle

of America Civil War, where more than 23,000 men died.

Now in attendance was a 9 year old boy named William V. Rathvon.

And in 1938, as he neared the end of his life, Rathvon took a copy of the speech and recorded

himself delivering it as he remembered Lincoln speaking it.

We don't have any audio of Lincoln delivering the speech, which makes this recording the

only one done by an eyewitness of the event. Pretty mind-blowing.

But what about sounds we don't wanna hear? For instance, fingernails scratching against

a blackboard. Well there are a lot of theories about why

that sound affects us so viscerally and so immediately.

Some of them argue that the sound of the scratching may mimic an early warning cry of early humans.

But more recent research suggests that it's actually certain frequencies inside that scratching

sound, specifically those between 2000 and 4000 Hz.

A range similar to the human voice. Our ear canals actually amplify those frequencies,

so that we can hear them better, but when it comes to the scratching of things on a

chalkboard, or styrofoam against styrofoam, those frequencies become too loud, making

it painful. Okay, now let's leave Earth and listen to

sounds from outer space. Now, I know what you're thinking, sound in

outer space is impossible. Sound waves need a medium to travel through

and in space you practically have a vacuum. I know.

But here's something really neat. The radio antenna on Voyager I was broadcasting

the signal back to Earth as Voyager passed through the rings of Saturn.

What you're about to listen to is that broadcast, and all the static and pings you hear are

actual pieces of Saturn's rings hitting the radio antenna.

But would outer space really be silent if I were to walk right out of a space craft

into it? I mean, I wouldn't survive very long, because

of a lack of air, a lack of air pressure, freezing temperatures, radiation, it would

be really terrible. But even though sound waves could not travel

through space itself, there is a medium that the sound can travel through.

My body. That's right.

As my blood boiled and my body inflated, it would vibrate my bones, it would vibrate my

body and in turn vibrate my ear drum, which is something that we experience every day

if you own a Justin Bieber singing toothbrush. Special toothbrushes like these vibrate in

a way that you can barely hear, but as soon as you bite down on it the vibrations go through

your jaw and jiggle your eardrum and you hear a quite high fidelity version of Justin Bieber's

"Baby" or "You Smile," which is fun. But what this really means is that in space

no one can hear you scream. But you can hear yourself inflate.

Okay, as you guys know, I'm in Alabama with Destin from SmarterEveryDay.

Now, even though I grew up in Kansas, I've never, in my entire life, fired a gun.

Well, Destin is a ballistics expert, he's one of the smartest guys I've ever met.

And tonight he's gonna let me fire a gun for the first time in my life.

This is a 9mm bullet, quite common. This is not gonna be the first thing I shoot

in my life. This is.

A 50 caliber bullet, Destin says it's a good idea, and that I'll be okay because I have

a beard.

And as always,

thanks for watching.