Elevator Transcript

Description:
An animation of an elevator.

Narrator:
In one of Einstein's famous thought experiments, he realized that gravity and acceleration appear to be the same phenomenon.

Description:
Einstein stands in the elevator.

Narrator:
Think about what would happen if an elevator suddenly went into a free-fall. The person inside would effectively weigh nothing.

Description:
Einstein floats in mid-air. Around him the elevator transforms into a rocketship's interior.

Narrator:
Next, imagine that same person in a motionless rocketship, so far from earth that the force of gravity is practically zero. Just like in the free-falling elevator, he would also weigh nothing.

Description:
In an exterior view, the rocketship floats in space.

Narrator:
Now, put the rocket in motion.

Description:
The rocket's engine fires. Einstein falls to the floor.

Narrator:
As the rocket speeds up, the passenger's weight increases. To him, it feels just as if gravity had planted his feet firmly on the floor.

Description:
From a squatting position, Einstein slowly rises. He steps backwards to regain his balance. The rocketship transforms back into an elevator.

Narrator:
Einstein realized that the force of gravity is actually the acceleration you feel as you move through space-time.

Description:
The elevator door swings open, allowing Einstein to exit.