Brian Cox visits the world's biggest vacuum chamber - Human Universe: Episode 4 Preview - BBC Two

This is massive space power facility in Cleveland, Ohio.

And it is the world's biggest vacuum chamber.

It's used to test space craft in the conditions of outer space.

And it does that by pumping out the 30 tons of air in this chamber.

Until there are about 2 grams left.

This kind of got an eccentric construction which is powered it's history,

it was built in the 1960's,

as a nuclear test facility to test nuclear proportion systems

and that meant that they build it out of aluminum

to make the radiation easier to deal with.

Aluminum is not the best thing,

the strongest material to build a vacuum chamber

so they build out of concrete skin

which is power radiation shield and imparts an external pressure vessel

so this thing can take the force present on the outside

when it pumps out to the conditions of outer space.

Galileo's experiment is simple,

it took a heavy object and a light one

and dropped them at the same time to see which fell fastest.

♪

Now on this case, the feathers fell to the ground

at a slower rate than the bowling ball

because of air resistance.

So in order to see the true nature of gravity

we have to remove the air.

It takes three hours to compact the 800 thousand cubic feet of air

for the chamber.

Okay we drop two mil-liter in the last 30 minutes.

But once it's complete there's a near

perfect vacuum inside.

6904, manual 10 percent open, station one go for drop.

Male giving instructions.

10, 9, 8, 7, 6, 5, 4, cameras on, 3, 2, 1, release.

♪

Laughing

They came down exactly the same time.

Exactly. Exactly the same.

Issac Newton would say ,

that the ball and the feather fall

BEcause there's a force pulling them down, gravity.

With Einstein would see imagine this scene differently.

The happiest thought of his life was this.

The reason the bowling ball and the feather

fall together is because they're not falling,

they're standing still, there is no force acting on them at all.

♪

A reason that if you couldn't see the background,

that the no way of knowing that the ball and the feathers

were being accelerated towards the earth.

So it concluded they weren't.