Sister, Sister, Why don't things fall up?

Sister, sister, I wonder… What do you wonder, little brother, What do you wonder? I wonder, I wonder, why things don’t fall up. What do you think, little brother, What do you think?

I think, I think… Tell me, little brother, what do you think?

I think That long ago, things did fall up That the sky was full of toffee wrappers And ice cream sticks That stars slipped on banana peels That sometimes, the moon cut her dainty feet On bits of broken glass Or caught her trailing silver skirts On a rusty nail.

I think The old woman who lives in the sky Got so tired of cleaning the mess That she put a curse on the earth; And things have fallen down ever since.

I think that’s why things don’t fall up Because the old woman in the sky Was fed up of living in a smelly pigsty. I’m clever, aren’t I, sister?

Oh yes, you are, little brother, And maybe you’re right, too… But in the books that I have read That is not what they said. Then what did they say, sister, What did they say? What do you think, little brother, What do you think? I think, I think… Tell me, little brother, what do you think?

I think That long ago, things did fall up And drove Mother mad. Father's keys, The screw of her nose-stud, The coins you were tossing from hand to hand (even though you knew Mother would scold if she knew) On your way back from the market; All fell up and disappeared.

Mother prayed to all her Gods. One of them took pity on her, And things fell down and vanished no more. Mother was happy (for a while) Now she complains about the mess on the floor. I think that’s why things don’t fall up All thanks to a woman’s pleas For fewer lost coins, and screws, and keys. I’m clever, aren’t I, sister?

I know you are, little brother, And maybe you’re right, too… But in the books that I have read That is not what they said. Then what did they say, sister, What did they say? What do you think, little brother, What do you think? I think, I think… Tell me, little brother, what do you think?

I think There is a big greedy demon inside the earth All day he waits, his mouth a gaping hole Sucking in mighty lungfuls of air… And nothing can fall up As long as he keeps sucking in — Everything heads towards that greedy hole.

I think Many things go right in. My marbles, your hairclips, The yummy laddoos Mother makes Which I don’t eat and you don’t eat But which disappear somehow. I think that is why things don’t fall up Because they hurtle earthwards to feed An underground demon’s greed. I’m clever, aren’t I, sister?

Of course you are, little brother, Of course you are And maybe you’re right, too… But in all the books that I have read That is not what they said. Then what did they say, sister, What did they say?

Come here, little brother, I’ll tell you what they said. They said, they said… Tell me what they said, sister, Tell me what they said.

They said That everything, just everything In the great big universe Pulls everything, just everything else In the great big universe Towards itself.

They said That BIG things can pull much harder At small things Than small things can pull At BIG things. But why don’t things fall up, sister, Why don’t things fall up? Be patient, little brother, be patient now.

They said The earth, our home, Is a very BIG thing And all of us, and everything else on earth— Our aeroplanes, our blue whales, even our oceans— Are very small things.

And that's why The earth pulls us towards itself MUCH, MUCH harder Than we can pull the earth Towards us. SO HARD That we, or our keys, or our screws, or our coins, Cannot escape, float away, disappear, Or fall up.

This GREAT force, this GIGANTIC force With which the earth pulls us All of us, Even the penguins at the edge of the earth, Towards itself Is called GRA-VI-TY. Can it be true, sister, can it be true? I can’t say, little brother, I can’t say. But in all the books that I have read That is what they said.

FIND OUT MORE!

Why don’t things fall up? About 350 years ago, a famous English scientist called Isaac Newton was relaxing under an apple tree when an apple fell and hit him SMACK! on the head. Rubbing his sore head, Newton wondered why things never fell up. Finally, he came up with the theory that the earth was like a giant magnet, which attracted everything around it with great force. He called this invisible force ‘gravity’.

He also concluded that everything in the universe attracts everything else. Bigger objects attract each other with greater force than smaller ones. Also, as the distance between two objects increases, the force of attraction between them decreases.

Gravity, however, does not just make apples fall down from trees. It also keeps the moon in orbit around the earth and all the planets in orbit around the sun. The force of the earth’s gravity keeps the moon from flying away into space.

But why doesn’t the moon fall towards the earth? Because the moon has its own gravity, with which it attracts the earth. It is because the earth’s gravity is greater, that the moon goes around the earth. If the moon’s was greater, the earth would have gone around the moon instead!

Try this experiment!

You need: A few rubber bands A small rubber ball A length of string

What to do: Put the rubber bands around the ball in such a way that they grip it tightly. Tie the string to one of the rubber bands around the ball. Stand somewhere where there is plenty of room and swing the ball around your head. If you swing it hard enough, the ball will go around your head in a horizontal circle. Now let go of the string. What happens? The ball flies away in a straight line.

Why does this happen?

Because there is a tension force in the string, which keeps the ball turning around your head. When you let go of the string, the tension force disappears and the ball goes flying.

Now imagine the ball is the moon and you are the earth. The earth's gravity is like the tension force in the string! If this tension force did not exist, the moon would fly away into space!