Matt Harden: Hey Bill, can you prove beyond
a reasonable doubt that the earth is a sphere
and not flat?
I have a lot of Facebook friends who say that
it's an act.
Thank you.
Bill Nye: Is the earth flat or round?
It's round.
Now, let's see, how do we go about proving
that?
Go to the seashore.
Go to the seashore and figure out why you
can't, if you live on the East Coast figure
out why you can't see Spain from the East
Coast or North America?
It looks like you might have a St. Louis hat
on.
I'm not sure.
Just go to the middle of the Mississippi River
and look south.
Why can't you see Louisiana?
Why can't you see New Orleans?
What's the problem there?
Then climb a tower or go to the top of a hill
or a mountain and you'll see a little farther,
but you will not see to the other side of
the earth, places we know to exist.
For example, I've been to London.
I can tell you other people have.
I've been to Vancouver British Columbia and
you cannot see Vancouver British Columbia
from Boise Idaho, let alone from New York
City Or Toronto or what have you.
Just start there then if you'd like look at
pictures from space where you see the earth
as a sphere.
Those pictures are not faked.
And I'll tell you if nothing else here is
why you can tell they're not faked.
Just to create the paperwork that NASA has
created, NASA in this one case, just the paperwork
to send anything out in space, to send people
into orbit or to send them to the moon, that
amount of paperwork would make faking it prohibitively
expensive.
No one could afford to generate that much
documentation.
Then the other thing if you want to get into
this, if your friends are really serious,
have them get on a boat or a ship and go out
at sea and you'll noticed you can't see infinitely
far.
Furthermore, if you get into it enough pick
up a book about navigation or go online and
learn about navigation.
A very, very Important thing you have to take
into account when you try to navigate the
ocean from a ship or a boat is how high you
are off the sea surface.
The higher you are off the sea surface the
farther you can see, the farther away the
horizon is.
Now, this discovery that the world is round
was made - I'm going to say it was published
in 1540.
Now, I concerned - it was Copernicus, I'm
concerned it might have been 1530, but it
was about then.
It was in the 16th century that the earth
was shown to be a ball.
But it was known to be a ball by a lot of
other people before Copernicus in the Western
World, what we now call the Western World
the western hemisphere.
The ancient Greeks noticed that from time
to time the earth casts a shadow on the moon.
This is a lunar eclipse's where the moon gets
in the shadow of the earth, the sunlight is
being blocked by the earth, the moon is on
the far side of the earth.
And that shadow is always curved.
And the only shape that always produces a
curve, no matter what the orientation, that
is to say whether you're standing in Greece
at night or if you're standing then 12 hours
later in Buenos Aries at night, the shadow
is always curved.
So the ancient Greeks knew that the earth
was a ball.
They didn't know the size of it to the degree
of precision we know now.
And you guys, come on, everybody watches newscasts.
You all use mobile phones.
You all see airplanes fly around.
You all go to see Ed Sheeran in concert one
day in London, another day in the Melbourne
Australia.
This all depends of our fundamental understanding
of the size of the earth and its shape with
extraordinary precision.
And if you want to get into it the earth isn't
quite a sphere, it's a little it's [NOISE],
its spin is a [NOISE] stretched, it made it
slightly oblate as the saying goes.
This is all susceptible to analysis, but spend
some time learning about navigation.
Tell your friends to spend some time learning
about navigation.
Navigation has change the world, by the way.
What are you wearing?
You're wearing stuff that came from another
part of the world on a ship.
It didn't get here by magic, it got here through
science.
