I remember in school being taught that the force of gravity was constant, so any object would fall at the same speed in a vacuum.

Apparently, Galileo claimed that if it wasn’t for air resistance, he could drop a cannonball and a feather from the top of the Leaning Tower of Pisa and they’d both hit the ground at the same time.

When I was young, I naturally didn’t believe it, it sounded ridiculous.

How could something weigh more than something else but both objects fall at the same speed?

Empirically, it just couldn’t be true.

But I didn’t bother arguing, I just thought “Yeah, yeah” and parked it along with all the other stuff from school I’d never need to know.

But over fifty years later, I experienced it as reality.

My daughter got us all tickets to see the ‘Moonwalkers’ show, it’s an immersive experience at London’s Lightrooms, it narrates the story of the moon landings on a grand scale.

The whole thing was spectacular, but one part hit me.

David Scott was commander of Apollo 15, he landed on the moon in the lunar module called Falcon.

On fuzzy black & white film he lumbers across the surface of the moon and talks to camera.

David Scott: “Here in my left hand I have a feather, in my right hand a hammer.

I guess one of the reasons we got here today was because of a gentleman named Galileo.

A long time ago he made a rather significant discovery about falling objects and gravity fields.

And we thought, where would be a better place to confirm his findings than on the moon?

So we thought we’d try it here for you.

And the feather happens to be appropriately a falcon feather, for our own Falcon.

I’ll drop the two of them here and hopefully they’ll hit the ground at the same time.


(Then he dropped them both at the same moment.

They fell slowly at the same speed.

And they hit the ground at the exact same moment.)


David Scott: How about that?

Mr. Galileo was correct in his findings.”


The hammer weighed nearly 3lbs (1.32 kg) the feather weighed 1oz (0.03kg).

So the hammer weighed more than 40 TIMES as much as the feather, but they both fell at exactly the same rate.

Because there is no atmosphere on the moon, and because its gravity is one sixth of Earth’s, it was easy to see it happening in slow motion.

It was no longer an abstract claim by some theoretical scientists, now it was observable fact.

And now my unshakeable belief is that it is definitely true.

Because a claim, even if made by scientists, connects rationally but not viscerally.

Whereas a demonstration does the opposite.

Many years ago I had to advertise a collapsible umbrella.

As everyone knows, the problem with collapsible umbrellas is their weakness, the wind blows them inside out.

We could claim this umbrella was stronger than others, but a claim doesn’t prove anything.

To be believable, we needed to prove it.

What would prove it was powerful enough to withstand the strongest storm?

So we had a man open the umbrella in a carwash.

As the water sprayed over him, the huge rollers turned the umbrella inside-out.

Instead of breaking, the man just popped the umbrella back to its original shape.

The rollers rolled over him again and he did it again.

We didn’t have to hope people believed our claim, we proved it.

People have been bitten too often by false advertising claims and lies from politicians.

If you want them to believe something you have to prove it.

And nothing works like a demo.