NARRATOR: Human vocal cords
produce sound
by disturbing the molecules
in the air around them.
Iceberg, straight ahead!
NARRATOR: The molecules begin
to vibrate in a distinct pattern
known as a sound wave.
Engine, full stop!
NARRATOR: The farthest
a human voice can travel
is about 600 feet
before the sound wave
runs out of energy.
If we want to communicate
over longer distances,
our voices have to hitch a ride
on another type of wave
that relies on a force
almost as old as the Universe.
Big History
brings in astrophysics
to connect us back
to the beginning of time.
(explosion)
The Big Bang: the birth
of all the matter and energy
that will ever exist
in the Universe
and the forces that govern
how it all works.
CLIFFORD JOHNSON: The forces
of nature we know now
began to distinguish themselves
and separate out.
One of the forces
that resulted from that process
is electromagnetism.
NARRATOR: Electromagnetism
gives sound a way to travel
that's more powerful
than air molecules
bumping into each other:
radio waves.
These waves are transmitted
by the vibration of electric
and magnetic fields,
and unlike the simple
sound wave,
radio waves can travel
vast distances.
NASA's Voyager 1 spacecraft
can send radio transmissions
to Earth
from the very edge
of the solar system,
12 billion miles away.
So a cell phone
extends the reach
of the sound waves
our voices make
by converting them
into radio waves
and transmitting them
through the atmosphere.
