Alex O'Connor

They describe how objects move when they're in motion.

Similarly, the example I love to give, because it's so explicit, is Newton's discovery of gravity.

What did Newton actually discover when he discovered gravity?

What's the thing that he actually figured out?

We had known for a very long time that objects fall to the ground, right?

What's the thing that he realized?

Well, Newton asked an interesting question.

He looks up at the moon and he asks, like, why isn't the moon falling towards the Earth?

And his sort of profound realization is that the moon is falling towards the Earth.

all the time.

It's just that if something falls towards my hand, it'll hit my hand.

But if I knock it to the side a little bit, then it'll kind of do this.

It'll kind of miss the earth a bit and then crash into the side.

And if I knock it a little bit further to the side, it will sort of miss it even more and maybe crash into the bottom eventually.

And if you knock it just the right speed to the side, it will keep falling towards the earth, but keep missing it.

And that's what we call orbit.

And Newton realized that the same thing that makes objects fall to the ground keeps the planets in circulation, which is a profound realization.

And then he took to the task of mathematically describing it.

Calculus, inverse square law.

So he figures out that the distance between two things, if you square that distance...