Spark and Perl go looking
How big is the universe?
I need to tell you a story first, and then I will explain the rest.
Are you ready?
All right, I am listening.
The story goes that a king was shown a new game. Sixty-four squares and two little armies. He played it every afternoon, all winter, until the snow went.
When spring came he sent for the man who had invented it, and offered him anything in the kingdom.
The man asked for wheat. Ten grains (10) on the first square of the board, a hundred (100) on the second, a thousand (1,000) on the third — ten times more on every square, all the way to the sixty-fourth.
The king said yes before he had finished listening. He was picturing a sack.
A whole chessboard of wheat?
That must be a sack.
Remember — he asked for ten grains (10) on the first square.
A hundred (100) on the second. A thousand (1,000) on the third…
Ten (10), a hundred (100), a thousand (1,000).
I can count that on my paws.
Square four is ten thousand (10,000). Square five is a hundred thousand (100,000).
Every square is ten times the one before it. That is the whole trick, and it is the only thing worth remembering today.
Then square one has one nought. And square two has two noughts. And square three has three!
They do. The noughts ARE the square number.
Square twenty has twenty of them. You never have to count again — you just read the square.
How much is that, though?
I cannot picture it.
A small loaf of bread — half a kilo — is about ten thousand grains.
That is square four. You have held a whole square in your paws.
Then the king got off lightly.
Square sixteen is half the wheat the whole world grows in a year. Every field, in every country.
Then all of it would not even fill square seventeen.
Not nearly. Square seventeen takes five whole harvests — and after it he still had forty-seven squares to go.
What does that even look like?
Pour one whole year of the world’s wheat into one heap and spread it out a little. It stands half a kilometre high and nearly three kilometres across.
The Eiffel Tower would come two thirds of the way up it.
Half a kilometre of wheat.
That is not a heap. That is a hill somebody could name.
So he never paid.
Nobody could.
And what has all that got to do with the universe?
We keep the same chessboard. We just put kilometres on it instead of grains.
Kilometres?
Ten kilometres on the first square — a long walk. Then square four is the Earth, straight across.
The loaf and the whole planet, on the same square?
The same square. Counted the same way. Loaf in grains and the width of the Earth in kilometres.
Walking all the way round is a bit more than three times as far as straight across.
And how far does the board go?
Now follow the board out — Jupiter, the Sun, the next star, the whole galaxy.
And the last one?
Square twenty-four. That is as far as anybody can see at all.
Because there is nothing past it?
Because the light has not arrived yet.
Light is quick, but it is not instant, and the universe has not been going for ever. Past square twenty-four there has not been time for the light to reach us. There may be a great deal there. We are simply too early.
So the board runs out before the universe does.
Not quite. What we can SEE runs out at twenty-four — and the board has sixty-four squares.
Forty of them are spare.
What is on the spare ones?
Nothing anyone has counted. Only numbers.
On a dark autumn night, find the Andromeda Galaxy: its light crossed about square nineteen to reach your garden. Then open Space and pull the zoom slider from one end to the other.
Every notch is another square. That slider is this chessboard, and it fits in your hand.
About
Space